appl. brochure nr. 42 metals in the mining industry
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AGC
Book
20%
Cya
n
42Application Brochure
General Titrators
Selected Applications Titration of Metals in the Mining Industry
Met
als
Min
ing
EDITORIAL Dear Reader Thank you for reading these lines and looking in our Application Brochure. You can expect detailed descriptions of selected metal determinations via titrimetric analysis. We don't present you a glossy brochure. It is a cookbook with proven recipes.Yet the result is not a cake but a reliable, precise and accurate number. Please follow the recipes diligently to get the most out of your analysis efforts. Titrators of METTLER TOLEDO support you. Easy to use thanks to One Click™ operation and color touchscreen. Simple to set instruments parameters thanks to preprogrammed methods. Smooth to link with your lab data system thanks to LabX software. “The proof of the pudding lies in the eating”, goes a British saying. Thus, we wish you successful "cooking and eating" with our recipes. We are sure that you achieve the top quality results you are working for.
Hans-Joachim Muhr Georg Reutemann Market Support Manager Manager New Projects and BA Titration Business Development LAB Division
METTLER TOLEDO
Contents
Method Title Gold - Au
M180 Estimation of the Approximate Gold Content in Alloys
M207 Titration of Gold -Au(I)- in a Standard Cyanide Solution
M297 Standardization of Cerium Sulfate vs. Hydroquinone
M298 Standardization of Hydroquinone and Cerium Sulfate with Pure Gold
M299 Determination of Gold
Silver - Ag
M195 Determination of Silver in Silver Alloys
Cyanide – CN-
M196 Determination of Free Cyanide in a Cyanidic Silver Bath
M465 Determination of Free Cyanide and Silver
Palladium – Pd
M462 Determination of Palladium Content
Copper – Cu
M460 Copper Content in Copper Mining Solutions
Iron – Fe
M459 Automated Determinaton of Iron Content in Iron Ores
M622 Determination of Total Iron Content of Iron Ores
M060 Determination of Iron (Fe(II) ) and Sulphuric Acid (H2SO4)
Chromium – Cr
M463 Determination of Cr(III) by Back-Titration in an Electroplating Bath
M464 Iodometric Titration of Cr(VI) in an Electroplating bath
Manganese – Mn
M461 Determination of Manganese in Manganese Ores
METTLER TOLEDO - I - Metals and metal mining
METTLER TOLEDO
Method Title Aluminum - Al
M466 Aluminum Content in Aluminum Ore (Bauxite) – Bayer Liquor
Boron - B
M222 Determination of Boric Acid in Acidic HCl/HF Solutions
Titanium -Ti
M467 Titanium Content in Mining Solutions
Cobalt - Co
M458 Determination of Cobalt Content in Alloy
Uranium - U
M292 Determination of Uranium according to Modified Davies-Gray Method
METTLER TOLEDO - II - Metals and metal mining
METTLER TOLEDO
METTLER TOLEDO - III - Metals and metal mining
Introduction
Metals with all their different material properties have contributed fundamentally to the progress of mankind. Since metals have been available centuries and millenniums ago, a continuous flow of innovations and new developments emerged. Weaponry and ornaments were first produced from metals such as copper, bronze or iron and ended the Neolithic stone age some 5000 years ago.
Metals are gained after a long and energy consuming production process from ores. At the end, there is the pure metal which consecutively undergoes further modifications according to its final use. The complete mining process from metallic ores to pure metal can be described as follows:
From the chemical point of view, the reduction reaction of the metal cations of the ores to the elemental metal is in the center of the mining process. Before this step, suitable preparation of the ores such as concentration or extraction is required to separate the metal compound from the rocks.
At the beginning, the geologic survey localizes the mineral deposits and assays of the ores evaluate yield expectations and extraction costs. At the end, melting in a blast or electric arc furnace in the presence of a suitable reducing agent such as carbon turns the metal cations from the minerals into the elemental metal. Subsequent refining by electrolytic techniques or other processes produces the pure final metals.
The determination of the metal content is thus required at different stages but is always related to the economics of the metals mining process. During the survey, the metal content is a decision factor if the ore is worth mining. Later purposes of analysis are process efficiency and safety or quality and purity of the final products.
Noble metals such as gold or silver being nearly resistant to corrosion occur thus as the metal already. The important production process besides the mining is the extraction of the noble metal from its gangue, a process which also requires careful monitoring and control.
Titration (titrimetric analysis) is a quantitative analytical method which accompanies the entire chain of the metal mining. It is a well proven and widespread analysis which nowadays comes with a large extent of automation from sample preparation to addition of reagents, result calculation and data storage.
METTLER TOLEDO's Excellence line titrators offer the right solution of titrator units, accessories such as sample changers or burettes and software to successfully compete with almost any requirements of titrimetric analysis. The easy One Click™ operation, robust and qualified instruments as well as moderate costs of purchase allow the use of titrators at all mining sites and in small testing labs equally.
Geologic survey
Assay of ores
Digging, mining
Size reduction
Concen-tration
Extrac-tion
Refining FinishingRetion duc-
METTLER TOLEDO
The main advantages of titrimetric methods such as linearity and high precision unfurl well appreciated benefits for the user:
• Linearity: Unlike spectroscopic techniques, titration is linear over the whole measuring range. Even at high concentrations, no dilution is required.
• High precision: Typical precision of titrimetric analyses is around 0.5%. In case of pure silver, the relative standard deviation can be as precise as 0.05%.
Equally important are the many titration methods available for the different metals which are tested and approved by a long history of practice.
The metals can be divided into different groups either depending on their properties, their occurrence, their use or other criteria. Commonly, base metals, iron and noble metals are distinguished.
Base Metals Examples: • Copper • Aluminium • Nickel • Zinc • Lead • Magnesium • Cobalt
Metals
Noble Metals Examples: • Gold • Silver • Platinum • Rhodium
Ferrous Metals Example: • Iron
Ores contain the metals usually as oxides, sulfides or silicates. As an example, the oxides magnetite Fe3O4 and hematite Fe2O3 are the major iron bearing minerals. Chalcopyrite CuFeS2, a sulfide, is the main mineral for the production of copper.
Besides the pure metals, alloys and metal compounds play an important role in our current civilization. Structures of skyscrapers and cars are made of metals and alloys to add the requisite strength and mechanical stability. Metals carry the electricity from the point of generation to the point of use hundreds of kilometers (or miles) apart. Or a third example, catalysts from metals or metal compounds support chemical reactions to produce ammonia (from nitrogen and hydrogen) or polymers (from ethylene or propylene), reduce exhaust gases (e.g. in cars) and harden fats and oils (e.g. for use in margarines).
METTLER TOLEDO - IV - Metals and metal mining
METTLER TOLEDO
Literature [1] O. Bazhko,
“Application of redox titration techniques for analysis of hydrometallurgical solutions”, in: “Hydrometallurgy Conference 2009”, The Southern African Institute of Mining and Metallurgy, 2009.
[2] A. I. Samchuk, A. T. Pilipenko, “Analytical Chemistry of Minerals”, Translated from the Russian by S. V. Ponomarenko VNU Science Press, Utrecht, The Netherlands, 1987.
[3] K.-H. Spitz, J. Trudinger, “Mining and the Environment: From Ore to Metal”, CRC Press, Taylor & Francis Group, 2009
[4] H. Hartman, J. Mutmansky, “Introductory Mining Engineering”, John Wiley and Sons, 2nd Edition, 2002.
[5] B. Lottermoser, “Mine Wastes: Characterization, Treatment and Environmental Impacts”, Springer, Berlin Heidelberg New York, 2nd Edition, 2007.
Links: - www.slideshare.net/LondonMiningNetwork/ore-mineralogy-and-orebodies
Excellent introduction on mining enginering.
- www.infomine.com InfoMine is a provider of mining knowledge online, delivering content via website, through corporate intranets, and by email.
- www.greatmining.com Information related to mining and mineral covering all aspects of global mining process from the base exploration to development and from environmental to social issues.
- www.onemine.org Comprehensive collection of data on mining and minerals based research including technical documents, conference papers, articles, pre-prints and late papers.
METTLER TOLEDO - V - Metals and metal mining
METTLER TOLEDO
METTLER TOLEDO - VI - Metals and metal mining
METTLER TOLEDO Application M180-2010
Estimation of the Approximate Gold Content in Alloys Estimation of gold content by reduction of gold ions in solution to elemental gold after addition of hydroquinone. Excess hydroquinone is determined by redox titration with cerium sulfate. This method is a fast test of the gold content. Application M299 allows for an accurate determination.
Preparation and Procedures CAUTION: work in a fume hood since gases are produced during dissolution of gold.
Alloy dissolution:
- Press alloys as thin as possible using a rolling device so that the dissolution is easier.
- Use an ultrasonic bath especially for silver containing alloys, because silver chloride does passivate the gold surface.
- Weigh 20-30 mg gold sample in a glass beaker.
- Add 5 mL HCl 32% and 1.5 mL HNO3 65%, and dissolve it on a heating plate (110-130°C).
- Evaporate to almost dryness, but never evaporate to complete dryness. This causes the reduction of gold leading to false results!
- Add again 5 mL HCl 32%, and evaporate again to almost dryness, but never evaporate to complete dryness.
- Rinse the beaker walls with a small amount (max. 10 mL) of deionized water or 5 mL 32% HCl. Cool down the sample before titration.
Titration:
- Place the titration beaker with the prepared sample on the manual titration stand.
- 30 mL HCl 0.1 mol/l will be pumped in automatically.
- Hydroquinone will be added automatically. The back titration is performed using a DMi140 redox electrode with cerium sulfate 0.01 mol/l.
Remarks
1. Pure gold is used as a standard.
2. Theoretical consumption: - 20 mg gold corresponds to 7.5 mL
hydroquinone, c(1/2 C6H6O2)=0.05 mol/L, and 7.0 mL cerium sulfate, c(Ce(SO4)2)=0.01 mol/L.
- 1 mL hydroquinone c c(1/2 C6H6O2)=0.05 mol/L corresponds to 5 mL cerium sulfate, c(Ce(SO4)2)= 0.01 mol/L.
Literature: METTLER TOLEDO Application Brochure “Gold and Silver”, ME-724613, 04/1994.
Sample Various gold alloys with unknown gold content, 30-60 mg
Compound Gold, Au M(Au) = 196.967 g/mol, z = 3
Chemicals 32% hydrochloric acid, HCl 65% nitric acid, HNO3 0.1 mol/L hydrochloric acid, HCl
Titrant Hydroquinone, C6H6O2 c(1/2 C6H6O2) = 0.05 mol/L Cerium(IV) sulfate, Ce(SO4)2 c(Ce(SO4)2) = 0.01 mol/L
Standard See M297 and M298 for standardization of titrants
Indication DMi140-SC (Pt ring) combined redox electrode
Chemistry Reduction with hydroquinone: 2Au3+ + 3C6H6O2 → 2Au + 6H+ + 3C6H4O2
Titration of excess hydroquinone: C6H6O2 + 2Ce4+ → C6H4O2 + 2Ce3+ + 2H+
Calculation Content (%): R1 = 100*(H[Hydroquinone]-Q[2])*C/m C1 = M/(1000*z) Content (carat): R2= 24*R1*C2 C2 = M/(1000*z) H[Hydroquinone] (Tx) or H5(DL7x) = dispensed hydroquinone amount
Waste disposal
HCl/HNO3: Neutralization with NaOH Hydroquinone: Evaporate solution,special waste Cerium: Precipitate with NaOH, filtrate, special waste Gold: Filtrate solution, special waste
Author, Version
MSG Anachem, April 1993 Revised January 2010/C. De Caro
METTLER TOLEDO Page 1 of 5 Titration Application M180-2010
Instruments - T50/T70/T90 Titration excellence, DL70ES/DL77 Titrators - XS205 Balance
Other titrators: This method can be also run with the DL55 and DL58 titrators (without peristaltic pump).
Accessories - 2 x 10 mL DV1010 burettes - Additional dosing unit (Tx) ME-51109030, or burette drive (DL5x, DL7x) - Glass titration beaker ME-101446 - SP250 Peristaltic pump ME-5108016
Results
Not available
Titration curve
1st Titration: 2Au3+ + 3C6H6O2 → 2Au + 6H+ + 3C6H4O2
2nd Titration: C6H6O2 + 2Ce4+ → C6H4O2 + 2Ce3+ + 2H+
METTLER TOLEDO Page 2 of 5 Titration Application M180-2010
METTLER TOLEDO Page 3 of 5 Titration Application M180-2010
Table of measured values
Not available
Comments
Principle:
To determine pure gold or its content in alloys the precipitation method with hydroquinone has been selected. Most of the associated metals do not interfere with the determination. As the precipitation of gold is too slow to execute a direct titration with hydroquinone, an excess of hydroquinone is added to the dissolved gold. The excess is titrated back with cerium(IV) sulfate:
1. Oxidation of gold: Gold is oxidized to Au3+ by aqua regia (conc. HCl/conc. HNO3 3:1 v/v). 2. Precipitation of gold:
Au3+ is reduced by excess hydroquinone and precipitates, and quinone is formed. Au3+ + 3 C6H6O2 = 2 Au + 3 C6H4O2 + 6 H+
3. Excess hydroquinone is oxidized by cerium(IV) sulfate (back-titration): 2 Ce4+ + C6H6O2 = C6H4O2 + 2 Ce3+ + 2 H+
Estimation of gold content (within approx. 3%):
With this method the gold content can be determined within approximately 3%. The gold content can then be determined accurately with application M299.
This test method consists of two titration functions:
1st TITRATION function: The gold reduction with hydroquinone is performed by a titration in order
• to determine the total amount of C6H6O2 dispensed • to obtain an excess of at least 1 mL C6H6O2 (titrant addition dV = 0.5 mL).
The total amount of hydroquinone dispensed is stored as auxiliary value H5.
2nd TITRATION function: Excess hydroquinone is back-titrated back with cerium(IV) sulfate.
Maintenance of the electrode:
We recommend to always clean the electrode after 6 gold titrations because gold contaminates the platinum ring by forming a thin layer: Place it for two minutes in aqua regia and rinse thoroughly with deionized water (See also leaflet of the DMi140-SC electrode).
Literature:
- A. Chow, “The Stability of Gold Solutions”, Talanta 18 (1971), pp. 453-456.
- S.C. Soundar Rajan and N. Appala Raju, “Titrimetric Determination of Gold by Precipitation with Hydroquinone”, Talanta 22 (1975), pp. 185-189.
METTLER TOLEDO Page 4 of 5 Titration Application M180-2010
DL70ES/DL77 Titrator
Method test Approximate gold content
Version 10-April-1993 11:09
Title
Method ID .......................... test
Title .............................. Approximate gold content
Date/time .......................... 10-April-1997 11:09
Sample
Number samples ..................... 1
Titration stand .................... Stand 1
Entry type ......................... Weight m
Lower limit [g] ................ 0.03
Upper limit [g] ................ 0.06
ID1 ................................ Gold
Molar mass M ....................... 196.967
Equivalent number z ................ 3
Temperature sensor ................. Manual
Pump
Auxiliary reagent ................. HCl 0.1 mol/L
Volume [mL] ........................ 40.0
Stir
Speed [%] .......................... 50
Time [s] ........................... 10
Titration
Titrant ............................ 1/2 C6H6O2
Concentration [mol/L] .............. 0.05
Sensor ............................. DM140-SC
Unit of meas. ...................... mV
Titration mode ..................... EQP
Titrant addition ............... INC
dV [mL]...................... 0.5
Measure mode ................... EQU
dE [mV]...................... 0.5
dt [s]....................... 2.0
t(min) [s]................... 10.0
t(max) [s]................... 40.0
Threshold ...................... 200.0
EQP range ...................... Yes
Limit A...................... 800
Limit B...................... 500
Maximum volume [mL] ............ 20.0
Termination after n EQPs ....... Yes
n = ......................... 1
Evaluation procedure ........... Standard
Auxiliary value
ID text ........................... Amount of C6H6O2
Formula ............................ H5=Q+QEX
Stir
Speed [%] .......................... 50
Time [s] ........................... 120
Titration
Titrant ............................ Ce(SO4)2
Concentration [mol/L] .............. 0.01
Sensor ............................. DM140-SC
Unit of meas. ...................... mV
Titration mode ..................... EQP
Titrant addition ............... DYN
dE(set) [mV]................. 8.0
Limits dV.................... Absolute
dV(min) [mL]............ 0.02
dV(max) [mL]............ 0.2
Measure mode ................... EQU
dE [mV]...................... 0.5
dt [s]....................... 2.0
t(min) [s]................... 3.0
t(max) [s]................... 30.0
Threshold ...................... 400.0
EQP range ...................... Yes
Limit A...................... 500
Limit B...................... 700
Maximum volume [mL] ............ 20.0
Termination after n EQPs ....... Yes
n = ......................... 1
Evaluation procedure ........... Standard
Calculation
Result name ........................ content
Formula ........................... R=100*(H5-Q[2])*C/m
Constant ........................... C=M/(1000*z)
Result unit ........................ %
Decimal places ..................... 1
Calculation
Result name ........................ content
Formula ........................... R2=24*(H5-Q[2])*C2/m
Constant ........................... C2=M/(1000*z)
Result unit ........................ carat
Decimal places ..................... 1
Report
Output unit ....................... Printer
All results ........................ Yes
Titration Excellence
Title
Type General titration
Compatible with T50 / T70 / T90
ID m180
Title Approximate gold content
Author admin
Date/Time 01.03.2010 10:30:00
Modified at 01.03.2010 10:30:05
Modified by admin
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Gold
Entry type Weight
Lower limit 0.03 g
Upper limit 0.06 g
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Arbitrary
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Pump
Auxiliary reagent HCl 0.1 mol/L
Volume [mL] 40.0
005 Stir
Speed 50%
Duration 10 s
Condition No
006 Titration (EQP) [1]
Titrant
Titrant 1/2 C6H6O2
Concentration 0.05 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 40%
Predispense
Mode None
Waiting time 0 s
Control
Control User
Titrant addition Incremental
dV 0.5 mL
Meas. val. acquisition Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 10 s
t (max) 40 s
Evaluation and recognition
Procedure Standard
Threshold 200 mV/mL
Tendency Negative
Ranges No
Add. EQP criteria No
Termination
At Vmax 20.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQP 1
Combined termination
criteria No
007 Auxiliary value
Name Hydroquinone
Formula H= Q[1]+QEX[1]
Limits No
008 Stir
Speed 50%
Duration 120 s
Condition No
009 Titration (EQP) [2]
Titrant
Titrant Ce(SO4)2
Concentration 0.01 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
METTLER TOLEDO Page 5 of 5 Titration Application M180-2010
Stir
Speed 40%
Predispense
Mode None
Waiting time 0 s
Control
Control User
Titrant addition Dynamic
dE(set value) 8.0 mV
dV(min) 0.02 mL
dV(max) 0.2 mL
Meas. val. acquisition Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 400 mV/mL
Tendency Positive
Ranges No
Add. EQP criteria No
Termination
At Vmax 10.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQP 1
Combined termination
criteria No
010 Calculation R1
Result content
Result unit %
Formula R1=
100*(H[Hydroquinone]-
Q[2])*C/m
Constant C=M/(1000*z)
M M[Gold]
z z[Gold]
Decimal places 1
Result limits No
Record statistics No
Extra statistical func. No
Send to buffer No
011 Calculation R2
Result content
Result unit carat
Formula R2=
24*(H[Hydroquinone]-Q[2])*C/m
Constant C=M/(1000*z)
M M[Gold]
z z[Gold]
Decimal places 1
Result limits No
Record statistics No
Extra statistical func. No
Send to buffer No
012 Record
Summary No
Results Per sample
Raw results Per sample
Table of meas. values All titration functions
Sample data No
Resource data No
E - V All titration functions
dE/dV - V All titration functions
log dE/dV - V No
d2E/dV2 - V No
BETA – V No
E - t No
V - t No
dV/dt - t No
T – t No
E – V & dE/dV – V No
V – t & dV/dt – t No
Method No
Series data No
Condition No
013 End of sample
METTLER TOLEDO Application M207-2010
Titration of Gold -Au(I)- in a Standard Cyanide Solution Content determination of gold Au(I) in an aqueous solution of potassium dicyanoaurate KAu(CN)2 by precipitation of AgAu(CN)2 with silver nitrate. The titration is monitored with a combined silver ring sensor.
Preparation and Procedures CAUTION: Cyanide is toxic!
A too low pH value i.e. below pH 3 leads to the formation of HCN gas which is toxic. Thus, work in a fume hood, use safety googles and wear gloves.
Standard solution:
- Weigh approx. 1.5 g potassium dicyanoaurate KAu(CN)2 in 250 mL volumetric flask. (This application: 1.46739 g).
- Fill up to the mark with deionized water.
Titration:
- Pipette 5 mL of the above standard solution into a titration beaker.
- Add 50 mL deionized water.
- Adjust to pH 3-5 by carefully adding 1 mol/L nitric acid (or more concentrated, if necessary).
- The titration is performed using a DM141 silver ring electrode with silver nitrate 0.1 mol/l as a titrant.
Remarks
- The method was developed on a DL40 titrator and was adapted for DL5x, DL7x , G20 and Titration Excellence titrators.
Literature:
- DL40 application no. 8121, 1981 (customer sample)
- METTLER TOLEDO Application Brochure No. 28 “electronics and Electroplating Applications”, 2007 (only available as PDF-file).
- Vogel's textbook of quantitative inorganic analysis, 4th edition, Longman Group Limited, 1978.
- See Application M525 (Brochure 18) for the standardization of silver nitrate.
Sample Standard solution, KAu(CN)2
5 mL c(KAu(CN)2) = approx. 6 g/L
Compound Gold, Au M(Au) = 196.967 g/mol, z = 1
Chemicals 50 mL deionized water 0.1 mol/L HNO3
Titrant Silver nitrate, c(AgNO3) = 0.1 mol/L
Standard Sodium chloride, NaCl See e.g. M525
Indication DMi141-SC (Ag ring) combined metal sensor
Chemistry With Au(I): Ag+ + Au(CN)2
- → AgAu(CN)2
Also possible with Au(III):
Ag+ + Au(CN)4- → AgAu(CN)4
Calculation Content (g/L):
R = Q*C/m
C = M/z
Waste disposal
HNO3: Neutralization with NaOH Gold, silver: Filtrate solution, special waste
CAUTION: Cyanide is toxic!
Author, Version
MSG Anachem, 1981 Revised February 2010/C. De Caro
METTLER TOLEDO Page 1 of 4 Titration Application M207-2010
Instruments - DL40 MemoTitrator - METTLER TOLEDO Balance, e.g. XS205
Other titrators: This method can be also run with the T50/T70/T90 Titration Excellence and G20 Compact Titrator, and with the DL5x and DL7x instruments (with major changes).
Accessories - 10 mL DV1010 burettes - Glass titration beaker ME-101446 - Printer
Results Au+ n Comments
Mean value 3.9978 g/L 5 DL40 application no. 8121
Theoretical 4.0134 g/L 1.46739 g KAu(CN)2 in 250 mL
Content deionized water
M(KAu(CN)2) = 288.07
Rel. standard 0.07 %
deviation srel
Titration curve
METTLER TOLEDO Page 2 of 4 Titration Application M207-2010
METTLER TOLEDO Page 3 of 4 Titration Application M207-2010
Table of measured values
Not available
Comments
• Monovalent gold ( Au(I) ), which is present as dicyanoaurate anion in solution, is precipitated as AgAu(CN)2 during titration with silver nitrate:
Ag+ + Au(CN)2- → AgAu(CN)2
• A similar precipitation reaction takes place when determining trivalent gold, i.e. Au3+ with silver nitrate as a titrant:
Ag+ + Au(CN)4- → AgAu(CN)4
• Nitric acid 0.1mol/L is added to increase the steepness of the potential jump at the equivalence point.
• If the standard solution should contain chloride, then the latter can be determined by continuing the analysis until a second equivalence point is evaluated. This is due to the precipitation of silver chloride in the sample solution.
• Gold electroplating baths contain free cyanide ions. Interference from free cyanide ions can be avoided by adjusting the pH to 5-6 using 30-40% formaldehyde solution. Generally, this solution has a pH value between 3 and 4. After a waiting time of 15-20 minutes, the titration can be started. The addition of formaldehyde leads to the formation of cyanohydrin compounds RR’C(OH)CN according to the general reaction between an aldehyde RHC=O or a ketone (RR’C=O) and free cyanide ions:
RHC=O + HCN → RHC(OH)CN
With formaldehyde, H2C=O, the reaction can be given as:
H2C=O + HCN → H2C(OH)CN
METTLER TOLEDO Page 4 of 4 Titration Application M207-2010
Method T50/T70/T90 Titration Excellence:
001 Title
Type General titration
Compatible with T50/T70/T90
ID m207
Title Au solution
Author Mettler Toledo
Date/Time 01.02.2010 15:00:00
Modified at 01.02.2010 15:00:10
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 KAu(CN)2
Entry type Fixed volume
Volume 5.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Stir
Speed 35%
Duration 10 s
Condition No
005 Titration (EQP) [1]
Titrant
Titrant AgNO3
Concentration 0.1 mol/L
Sensor
Type mV
Sensor DMi141-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode None
Waiting time 0 s
Control
Control User
Titrant addition Dynamic
dE (set value) 8 mV
dV (min) 0.02 mL
dV (max) 0.2 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 5 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 800
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 10 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
006 Calculation R1
Result Au Content
Result unit g/L
Formula R1 = Q*C/m
Constant C= M/z
M M[Gold]
z z[Gold]
Decimal places 4
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
007 End of sample
008 Report
Summary Yes
...
DL5x Titrators:
Title
Method ID ............................m207
Title ................................Au solution
Date/time ............................01-02-2010 15:00
Sample
Sample ID ............................KAu(CN)2
Entry type ...........................Fixed volume
Volume [mL] ..........................5.0
Molar mass M .........................196.97
Equivalent number z .................1
Titration stand ......................Stand 1
Temperature sensor ...................Manual
Stir
Speed [%] ............................50
Time [s] .............................10
EQP titration
Titrant/Sensor
Titrant ..............................AgNO3
Concentration [mol/L] ................0.1
Sensor ...............................DM141-SC
Unit of meas. .......................mV
Predispensing ........................No
Titrant addition .....................Dynamic
dE(set) [mV] .........................8.0
dV(min) [mL] .........................0.02 dV(max) [mL] .........................0.2 Measure mode ........................Equilibrium
.....................................controlled
dE [mV] ..............................0.5
dt [s] ...............................2.0
t(min) [s] ...........................5.0
t(max) [s] ...........................30.0
Recognition
Threshold ............................800
Steepest jump only ..................No
Range ................................No
Tendency .............................Positive
Termination
at maximum volume [mL] ...............10.0
at potential .........................No
at slope .............................No
after number EQPs ....................Yes
n = .................................1
comb. termination criteria ..........No
Evaluation
Procedure ............................Standard
Potential 1 ..........................No
Potential 2 ..........................No
Stop for reevaluation ................Yes
Condition ...........................neq=0
Calculation
Formula .............................R=Q*C/m
Constant .............................C=M/z
Decimal places .......................4
Result unit ..........................g/L
Result name ..........................Au content
Statistics ...........................Yes
Calculation
Formula ..............................R2=VEQ
Constant .............................
Decimal places .......................3
Result unit ..........................mL
Result name ..........................Consumption
Statistics ...........................Yes
Calculation
Formula ..............................
Constant .............................
Decimal places .......................0
Result unit ..........................
Result name ..........................
Statistics ...........................No
Report
Output ..............................Printer
Results ..............................No
All results ..........................Yes
Raw results ..........................No
Table of measured values .............Yes
Sample data ..........................No
E - V curve ..........................Yes
dE/dV - V curve ......................Yes d2E/dV2 - V curve ....................No
log dE/dV - V curve ..................No E - t curve ..........................No
V - t curve ..........................No
dV/dt - t curve ......................No
METTLER TOLEDO Application M297-2007
Standardization of Cerium Sulfate vs. Hydroquinone Titer determination of cerium sulfate by redox titration of hydroquinone aqueous solution. The result –a relative factor- is used in applications M298 (standardization hydroquinone and cerium sulfate vs. gold) and M299 (determination of gold).
Preparation and Procedures Titration:
- Place an empty glass titration beaker on the manual titration stand
- 40 mL HCl 0.1 mol/l will be pumped in automatically
- 1.5 mL hydroquinone will be dispensed
- The sample will be titrated with cerium(IV) sulfate 0.01 mol/L using a DMi140-SC sensor.
Hydroquinone solution, c(1/2 C6H6O2) = 0.05 mol/L:
- Weigh 2.753 g hydroquinone in a glass beaker
- Transfer with deionized water into a 1 L measuring flask
- Add approx. 900 mL deionized water
- Add 10 mL H2SO4 96%
- Fill up to the mark with deionized water
Cerium sulfate solution, c(Ce(SO4)2) = 0.01 mol/L:
- Pipette 50.0 mL of cerium sulfate 0.1 mol/L (e.g. Merck 1.09092.1000) in a 500 mL volumetric flask.
- Add approx. 400 mL deionized water
- Add 10 mL H2SO4 96% and gently mix it
- Fill up to the mark with deionized water
The cerium(IV) sulfate solution is unstable because a precipitation occurs. It is recommended to prepare a new solution every 2 days.
The hydroquinone solution is stable but it is recommended to prepare a new solution every 10 days
Remarks
Theoretical consumption: 1 mL hydroquinone, c(1/2 C6H6O2) = 0.05 mol/L, corresponds to 5 mL cerium(IV) sulfate, c(Ce(SO4)2)= 0.01 mol/L. Literature: METTLER TOLEDO Application Brochure “Gold and Silver”, ME-724613, 04/1994.
Sample Hydroquinone, C6H6O2
c (1/2 C6H6O2) = 0.05 mol/L 1.5 mL
Compound Hydroquinone, C6H6O2
M(C6H6O2) = 110.11 g/mol, z = 2
Chemicals 0.1 mol/L hydrochloric acid, HCl
Titrant Cerium(IV) sulfate, Ce(SO4)2 c(Ce(SO4)2) = 0.01 mol/L
Standard --
Indication DMi140-SC (Pt ring) combined redox sensor
Chemistry C6H6O2 + 2 Ce4+ →
C6H4O2 + 2 Ce3+ + 2 H+
Calculation R1 = VENDDi*0.05/(VEQ*c) C1 = 1 Result is stored as auxiliary value: H[Cerium sulfate] = Mean [R1]
Waste disposal
Hydroquinone: Evaporate solution,special waste Cerium: Precipitate with NaOH, filtrate, special waste
Author, Version
Claudia Schreiner, MSG Anachem, April 2007
METTLER TOLEDO Page 1 of 4 Titration Application M297-2007
Instruments - T50/70/T90 Titration Excellence with LabX titration - XS205 Balance
Other titrators: This method can be also run with the DL5x and DL7x instruments (with method changes).
Accessories - 2 x 10 mL DV1010 burettes - Additional dosing unit ME-51109030 - Glass titration beaker ME-101446 - SP250 Peristaltic pump ME-5108016
Results Start time: 22.03.2007 Sample Data Note / ID Sample size No. 1/6 Hydroquinone 1.5 mL No. 2/6 Hydroquinone 1.5 mL No. 3/6 Hydroquinone 1.5 mL No. 4/6 Hydroquinone 1.5 mL No. 5/6 Hydroquinone 1.5 mL No. 6/6 Hydroquinone 1.5 mL Results Note / ID Rx Result Unit No. 1/6 Hydroquinone R1= 0.9828 -- No. 2/6 Hydroquinone R1= 0.9822 -- No. 3/6 Hydroquinone R1= 0.9829 -- No. 4/6 Hydroquinone R1= 0.9832 -- No. 5/6 Hydroquinone R1= 0.9833 -- No. 6/6 Hydroquinone R1= 0.9836 -- Statistics Rx Name n Mean Value Unit s srel[%] R1 Factor 6 0.9830 -- 0.0005 0.05
Titration curve
sample 1/5
METTLER TOLEDO Page 2 of 4 Titration Application M297-2007
METTLER TOLEDO Page 3 of 4 Titration Application M297-2007
Table of measured values
Volume lncrement Signal Change 1. Derivative Time mL mL mV mV mV/mL s 0.000 NaN 381.7 NaN NaN 0 2.857 2.857 429.0 47.3 NaN 14 4.286 1.429 440.1 11.1 NaN 24 5.000 0.714 446.0 5.9 NaN 30 5.200 0.200 448.7 2.7 NaN 39 5.400 0.200 451.4 2.7 9.01 43 5.600 0.200 452.6 1.2 9.83 46 5.800 0.200 454.2 1.6 9.60 50 6.000 0.200 456.0 1.8 8.75 53 6.200 0.200 458.1 2.1 9.99 56 6.400 0.200 460.2 2.1 11.79 59 6.600 0.200 462.9 2.7 9.55 62 6.800 0.200 465.7 2.8 5.89 66 7.000 0.200 469.6 3.9 21.83 70 7.200 0.200 474.2 4.6 115.11 76 7.400 0.200 480.4 6.2 404.51 83 7.600 0.200 502.5 22.1 1244.86 86 7.626 0.026 558.2 55.7 1962.45 117 7.631 0.005 661.1 102.9 2970.64 147 EQP1 (1) 7.631 NaN 664.6 NaN NaN NaN 7.636 0.005 725.9 64.8 2577.51 177 . . . . . . . . . . . . . . . . . . 8.270 0.172 842.8 8.9 49.62 301 8.464 0.194 850.7 7.9 37.38 305 8.664 0.200 857.6 6.9 29.70 308 8.664 0.200 862.5 4.9 25.05 313 9.064 0.200 867.8 5.3 21.28 316 9.264 0.200 871.4 3.6 NaN 320 9.464 0.200 875.0 3.6 NaN 323 9.664 0.200 878.5 3.5 NaN 326 9.864 0.200 881.2 2.7 NaN 329 10.000 0.136 883.1 1.9 NaN 332 sample1/5
Comments
To determine pure gold or its content in alloys the precipitation method with hydroquinone has been selected. Most of the associated metals do not interfere with the determination.
As the precipitation of gold is too slow to execute a direct titration with hydroquinone, an excess of hydroquinone is added to the dissolved gold. The excess is titrated back with cerium(IV) sulfate:
1. Oxidation of gold: Gold is oxidized to Au3+ by aqua regia (conc. HCl/conc. HNO3 3:1 v/v).
2. Precipitation of gold: Au3+ is reduced by excess hydroquinone and precipitates, and quinone is formed.
Au3+ + 3 C6H6O2 = 2 Au + 3 C6H4O2 + 6 H+
3. Excess hydroquinone is oxidized by cerium(IV) sulfate (back titration):
2 Ce4+ + C6H6O2 = C6H4O2 + 2 Ce3+ + 2 H+
It has been shown (Ref. 1) that copper, iron, zinc, nickel, platinum and palladium do not interfere. We have found in our own work that silver does not interfere.
Application M298 (Standardization of hydroquinone and cerium(IV) sulfate vs. gold) and M299 (Determination of gold) complete the whole analysis for the gold content titration.
The complete analysis sequence consists of the following steps: 1) M297 2) M298 3) M299 Literature: 1. S.C. Soundar Rajan and N. Appala Raju, “Titrimetric Determination of Gold by Precipitation with
Hydroquinone”, Talanta 22 (1975), pp. 185-189. 2. A. Chow, “The Stability of Gold Solutions”, Talanta 18 (1971), pp. 453-456.
METTLER TOLEDO Page 4 of 4 Titration Application M297-2007
Method 001 Title
Type General titration
Compatible with T50/T70/T90
ID m297
Title Factor cerium sulfate
Author Mettler Toledo
Date/Time 05.04.2007 10:39:52
Modified at 05.04.2007 10:39:52
Modified by admin
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Hydroquinone
Entry type Fixed volume
Volume 1.5 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Arbitrary
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Pump
Auxiliary reagent HCl 0.1 mol/L
Volume [mL] 40
Condition No
005 Dispense
Titrant ½ Hydroquinone
Concentration 0.05 mol/L
Volume 1.5
Dosing rate 60.0 mL/min
Condition No
006 Stir
Speed 35%
Duration 10 s
Condition No
007 Titration (EQP) [1]
Titrant
Titrant Cerium sulfate
Concentration 0.01 mol/L
Sensor
Type mV
Sensor DM140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 5
Waiting time 5 s
Control
Control User
Titrant addition Dynamic
dE (set value) 8 mV
dV (min) 0.005 mL
dV (max) 0.2 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 500
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 10 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EPQs 1
Combined termination
criteria No
Accompanying stating
Accompanying stating No
Condition
Condition No
008 Calculation R1
Result Factor
Result unit -
Formula R1=VENDDi*0.05/(VEQ*c)
Constant C= 1
M M[None]
z z[None]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
009 End of sample
010 Auxiliary value
Name Cerium sulfate
Formula H= Mean[R1]
Limits No
Condition No
METTLER TOLEDO Application M298-2007
Standardization of Hydroquinone and Cerium Sulfate with Pure Gold Titer determination of hydroquinone by means of pure gold as a standard. Gold ions are reduced to elemental gold after addition of hydroquinone. Excess hydroquinone is determined by redox titration with cerium sulfate. The result is used in M299 (determination of gold).
Preparation and Procedures CAUTION: work in a fume hood since gases are produced during dissolution of gold.
Gold dissolution:
- Weigh 20-30 mg gold sample in a glass beaker
- Add 5 mL HCl 32% and 1.5 mL HNO3 65%. Never use prepared aqua regia, it is unstable!
- Dissolve it on a heating plate (110-130°C).
- Evaporate to almost dryness, but never evaporate to complete dryness. This causes the reduction of gold leading to false results!
- Repeat addition of 5 mL HCl 32%.
- Repeat again evaporation to almost dryness, but never evaporate to complete dryness.
- Rinse the beaker walls with a small amount (max. 10 mL) of deionized water or 5 mL 32% HCl. Let the sample cool down before starting the titration.
Titration:
- Place the titration beaker with the prepared sample on the manual titration stand.
- 30 mL HCl 0.1 mol/l will be pumped in automatically.
- Hydroquinone (1/2 C6H6O2) will be added automatically. Note: The volume to be dispensed is calculated in the method to achieve an optimum titrant consumption of 7 mL.
- The back titration is performed using a DMi140-SC redox sensor with cerium(IV) sulfate 0.01 mol/l.
Remarks
1. Theoretical consumption: - 20 mg gold corresponds to 7.5 mL
hydroquinone, c(1/2 C6H6O2)=0.05 mol/L, and 7.0 mL cerium sulfate, c(Ce(SO4)2)=0.01 mol/L.
- 1 mL hydroquinone, c(1/2 C6H6O2)=0.05 mol/L corresponds to 5 mL cerium sulfate, c(Ce(SO4)2)= 0.01 mol/L.
Literature: METTLER TOLEDO Application Brochure “Gold and Silver”, ME-724613, 04/1994.
Sample Pure gold, 20-30 mg
Compound Gold, Au M(Au) = 196.967 g/mol, z = 3
Chemicals 32% hydrochloric acid, HCl 65% nitric acid, HNO3 0.1 mol/L hydrochloric acid, HCl 96% sulfuric acid, H2SO4
Titrant Hydroquinone, C6H6O2 c(1/2 C6H6O2) = 0.05 mol/L Cerium sulfate, Ce(SO4)2 c(Ce(SO4)2) = 0.01 mol/L
Standard --
Indication DMi140-SC (Pt ring) combined redox sensor
Chemistry Reduction with hydroquinone: 2 Au3+ + 3 C6H6O2 → 2 Au + 6 H+ + 3 C6H4O2
Titration of excess hydroquinone: C6H6O2 + 2 Ce4+ → C6H4O2 + 2 Ce3+ + 2 H+
Calculation Predispensing Ce(SO4)2 : R1=QENDDi/(H[Cerium sulfate]*0.01)-C C=m*1523*H[Cerium sulfate] Titer hydroquinone vs. gold: R2=C/(QENDDi-VEQ*c*H[Cerium sulfate]) C=(m*1000*z)/M Titer cerium(IV) sulfatevs. gold: R3=Mean[R2]*H[Cerium sulfate] C=1
Waste disposal
HCl/HNO3: Neutralization with NaOH Hydroquinone: Evaporate solution,special waste Cerium: Precipitate with NaOH, filtrate, special waste Gold: Filtrate solution, special waste
Author, Version
Claudia Schreiner, MSG Anachem, April 2007
METTLER TOLEDO Page 1 of 7 Titration Application M298-2007
Instruments - T70/T90 Titration Excellence with LabX titration - XS205 Balance
Other titrators: This method can be also run with the DL55/DL58 and DL70ES/DL77 titrators with method changes). T50, DL50 Graphix, DL53 and DL67 require manual operations.
Accessories - 2 x 10 mL DV1010 burettes - Additional dosing unit ME-51109030 - Glass titration beaker ME-101446 - SP250 Peristaltic pump ME-5108016
Results Start time: 27.03.2007
Sample Data Note / ID Sample size
No. 1/5 Fluka Gold 0.03064 g
No. 2/5 Fluka Gold 0.02525 g
No. 3/5 Fluka Gold 0.02187 g
No. 4/5 Fluka Gold 0.02082 g
No. 5/5 Fluka Gold 0.02255 g
Results Note / ID Rx Result Unit
No. 1/5 Fluka Gold R2= 1.0004 --
R3= 0.9892 --
No. 2/5 Fluka Gold R2= 0.9857 --
R3= 0.9747 --
No. 3/5 Fluka Gold R2= 0.9981 --
R3= 0.9870 --
No. 4/5 Fluka Gold R2= 1.0036 --
R3= 0.9924 --
No. 5/5 Fluka Gold R2= 0.9994 --
R3= 0.9872 -–
Statistics
Rx Name n Mean Value Unit s srel[%]
R1 Titer 1/2 Hydroquinone vs gold 5 0.9974 -- 0.007 0.69
R2 Titer Cerium(IV) sulfatevs gold 5 0.9861 -- 0.007 0.68
Titration curve
sample 1/5
METTLER TOLEDO Page 2 of 7 Titration Application M298-2007
METTLER TOLEDO Page 3 of 7 Titration Application M298-2007
Table of measured values Volume Increment Signal 1st Derivative Time Temperature mL mL mV mV/mL s °C 0.000 NaN 479.000 NaN 0.000 25.000 3.220 3.220 486.800 NaN 10.000 25.000 4.829 1.609 496.900 NaN 17.000 25.000 5.634 0.805 503.700 NaN 23.000 25.000 5.834 0.200 505.600 NaN 38.000 25.000 6.034 0.200 508.400 24.310 42.000 25.000 6.234 0.200 511.700 31.110 47.000 25.000 6.434 0.200 516.100 40.000 52.000 25.000 6.634 0.200 522.700 63.190 57.000 25.000 6.834 0.200 536.400 157.890 64.000 25.000 6.903 0.069 545.500 251.360 67.000 25.000 6.934 0.031 553.600 370.210 72.000 25.000 6.950 0.016 558.400 504.270 76.000 25.000 6.973 0.023 572.500 917.050 86.000 25.000 6.979 0.006 578.300 1112.690 91.000 25.000 6.934 0.005 585.400 1107.130 101.000 25.000 6.909 0.005 593.700 1396.460 114.000 25.000 6.994 0.005 597.300 1581.450 120.000 25.000 7.007 0.013 623.100 1905.420 147.000 25.000 7.012 0.005 632.700 2022.650 160.000 25.000 7.017 0.005 638.700 1994.060 166.000 25.000 EQPI 7.017 NaN 639.300 1953.990 NaN NaN 7.028 0.011 665.600 1507.130 192.000 25.000 7.033 0.005 673.200 1333.730 200.000 25.000 7.041 0.000 684.100 1134.510 211.000 25.000 7.049 0.000 690.500 NaN 210.000 25.000 7.063 0.014 697.300 NaN 222.000 25.000 7.092 0.029 708.600 NaN 227.000 25.000 7.117 0.025 717.000 NaN 232.000 25.000 7.141 0.024 726.000 NaN 236.000 25.000 sample1/5
Comments
Principle: To determine pure gold or its content in alloys the precipitation method with hydroquinone has been selected. Most of the associated metals do not interfere with the determination. As the precipitation of gold is too slow to execute a direct titration with hydroquinone, an excess of hydroquinone is added to the dissolved gold. The excess is titrated back with cerium sulfate:
1. Oxidation of gold: Gold is oxidized to Au3+ by aqua regia (conc. HCl/conc. HNO3 3:1 v/v). 2. Precipitation of gold:
Au3+ is reduced by excess hydroquinone and precipitates, and quinone is formed. Au3+ + 3 C6H6O2 → 2 Au + 3 C6H4O2 + 6 H+
3. Excess hydroquinone is oxidized by cerium (IV) sulfate (back titration): 2 Ce4+ + C6H6O2 → C6H4O2 + 2 Ce3+ + 2 H+
It has been shown (Ref. 1) that copper, iron, zinc, nickel, platinum and palladium do not interfere. We have found in our own work that silver does not interfere.
Application M297 (Factor cerium(IV) sulfate vs. hydroquinone) and M299 (Determination of gold) complete the whole analysis for the gold content titration.
The complete analysis sequence consists of the following steps: 1) M297 2) M298 3) M299
Accuracy: The accuracy which can be obtained by these methods depends on:
1. the weighing and handling procedures e.g. use a balance with high resolution and tweezers 2. the care with which the gold sample is prepared and dissolved. 3. the amount of gold taken. 4. the accuracy of titration method and titrator.
Maintenance of the electrode: We recommend to always clean the electrode after 6 gold titrations because gold contaminates the platinum ring by forming a thin layer: Place it for two minutes in aqua regia and rinse thoroughly with deionized water (See also leaflet of the DMi140-SC electrode).
Literature: 1. S.C. Soundar Rajan and N. Appala Raju, “Titrimetric Determination of Gold by Precipitation with
Hydroquinone”, Talanta 22 (1975), pp. 185-189. 2. A. Chow, “The Stability of Gold Solutions”, Talanta 18 (1971), pp. 453-456.
Principle of titration method
METTLER TOLEDO Page 4 of 7 Titration Application M298-2007
Principle of titration method
006 Dispense (Hydroquinone) A known excess of hydroquinone is dispensed depending on the size of the gold standard. The optimum titrant consumption for back-titration with cerium(IV) sulfateis set to approx. 7 mL. The predispensing volume VENDDi of hydroquinone solution is calculated accordingly.
008 Calculation (Amount of cerium(IV) sulfateto be predispensed) A predispensing of 70% of cerium(IV) sulfateis used to speed up the titration time. It is calculated based on the predispensing of hydroquinone (QENDDi) and on the gold standard amount.
009 Titration (EQP, back- titration with cerium sulfate) Here the predispensing of cerium(IV) sulfatetitrant is calculated from the result of function 008 Calculation.
010 Calculation (Titer ½ C6H6O2 vs. gold) The titer of hydroquinone, ½ C6H6O2, is determined using pure gold as standard. It is calculated and stored as auxiliary value H[Titer ½ C6H6O2 vs gold] in function 013.
011 Calculation (Titer Ce(SO4)2 vs. gold) The auxiliary value H[Cerium sulfate] is obtained by standardization of cerium(IV) sulfatewith hydroquinone (M297). The titer of cerium sulfate, Ce(SO4)2, must be now referred to pure gold. This is determined in function 011 Calculation. It is stored as auxiliary value H[Titer Ce(SO4)2 vs gold] in function 014.
013 Auxiliary value: H[Titer ½ C6H6O2 vs. gold] = Mean[R2]
METTLER TOLEDO Page 5 of 7 Titration Application M298-2007
METTLER TOLEDO Page 6 of 7 Titration Application M298-2007
Principle of titration method
Summary of the method parameters:
Parameter Symbol Unit Predispense Cerium sulfate VENDDi [mL]
Predispense Cerium sulfate QENDDi [mmol]
Consumption Cerium sulfate Q [mmol]
Equivalent number of gold z 3
Size of gold sample [g] m 0.02-0.03
Molar mass of gold [g/mol] M 196.967
Titrant Cerium sulfate [mol/L] c (Ce(SO4)2) 0.01
Titrant Hydroquinone [mo/L] c (½ C6H6O2) 0.05
Preparation of the reagents
Hydroquinone solution, c(1/2 C6H6O2) = 0.05 mol/L:
- Weigh 2.753 g Hydroquinone in a glass beaker
- Transfer with deionized water into a 1 L measuring flask
- Add approx. 900 mL deionized water
- Add 10 mL H2SO4 96%
- Fill up to the mark with deionized water
Cerium(IV) sulfatesolution, c(Ce(SO4)2) = 0.01 mol/L:
- Pipette 50.0 mL of cerium(IV) sulfate0.1 mol/L (e.g. Merck 1.09092.1000) in a 500 mL volumetric flask
- Add approx. 400 mL deionized water
- Add 10 mL H2SO4 96% and gently mix it
- Fill up to the mark with deionized water
Note:
• The cerium(IV) sulfatesolution is unstable because a precipitation occurs. We recommend preparing a new solution every 2 days.
• The hydroquinone solution is stable but we recommend preparing a new solution every 10 days.
• Gold sample: Solid gold is dissolved in strong oxidizing acid solution and evaporated to almost dryness (never to complete dryness). If necessary, this procedure has to be repeated until no yellow fumes (nitrous gases) are formed anymore. For the sample sizes used (20-30 mg), the procedure was repeated once.
METTLER TOLEDO Page 7 of 7 Titration Application M298-2007
Method 001 Title
Type General titration
Compatible with T50/T70/T90
ID m298
Title Factor Hydroquinone Solution
Author Mettler Toledo
Date/Time 08.03.2007 15:01:02
Modified at 05.04.2007 10:42:46
Modified by admin
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Gold
Entry type Weight
Lower limit 0.02 g
Upper limit 0.03 g
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Arbitrary
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Pump
Auxiliary reagent HCl 0.1 mol/L
Volume [mL] 30
Condition No
005 Stir
Speed 50%
Duration 5 s
Condition No
006 Dispense
Titrant ½ C6H6O2
Concentration 0.05 mol/L
Volume 304.6*m+1.4*H[Cerium sulfate]
Dosing rate 60.0 mL/min
Condition No
007 Stir
Speed 50%
Duration 180 s
Condition No
008 Calculation R1
Result Predispense cerium sulfate
Result unit mL
Formula R1=
QENDDi/(H[Cerium sulfate]*0.01)-C
Constant C= m*1523*H[Cerium sulfate] M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
009 Titration (EQP) [1]
Titrant
Titrant Ce(SO4)2
Concentration 0.01 mol/L
Sensor
Type mV
Sensor DM140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 40%
Predispense
Mode Volume
Volume 0.7*R1
Waiting time 10 s
Control
Control User
Titrant addition Dynamic
dE (set value) 8 mV
dV (min) 0.005 mL
dV (max) 0.2 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 200
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 15 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Combined termination
criteria No
Accompanying stating
Accompanying stating No
Condition
Condition No
010 Calculation R2
Result Titer ½ C6H6O2 vs. gold
Result unit -
Formula R2=
C/(QENDDi-VEQ*c*H[Cerium sulfate])
Constant C= (m*z*1000)/M
M M[Gold]
z z[Gold]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
011 Calculation R3
Result Titer Ce(SO4)2 vs. gold
Result unit -
Formula R3=Mean[R2]*H[Cerium sulfate]
Constant C= 1
M M[None]
z z[None]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
012 End of sample
013 Auxiliary value
Name Titer 1/2 C6H6O2 vs. gold
Formula H= Mean[R2]
Limits No
Condition No
014 Auxiliary value
Name Titer Ce(SO4)2 vs. gold
Formula H= Mean[R3]
Limits No
Condition No
METTLER TOLEDO Application M299-2007
Determination of Gold Content determination of gold by reduction of gold ions in solution to elemental gold after addition of hydroquinone. Excess hydroquinone is determined by redox titration with cerium(IV) sulfate. Applications M297 and M298 describe the standardization of the used titrants.
Preparation and Procedures CAUTION: work in a fume hood since gases are produced during dissolution of gold.
Gold dissolution:
- Weigh 20-30 mg gold sample in a glass beaker
- Add 5 mL HCl 32% and 1.5 mL HNO3 65%.
- Dissolve it on a heating plate (110-130°C).
- Evaporate to almost dryness, but never evaporate to complete dryness. This causes the reduction of gold leading to false results!
- Repeat addition of 5 mL HCl 32%.
- Repeat evaporation to almost dryness, but never evaporate to complete dryness.
- Rinse the beaker walls with a small amount (max. 10 mL) of deionized water or 5 mL 32% HCl. Let the sample cool down before starting titration.
Titration:
- Place the titration beaker with the prepared sample on the manual titration stand.
- 30 mL HCl 0.1 mol/l is pumped in automatically.
- Hydroquinone (1/2 C6H6O2) will be added automatically. Note: The volume to be dispensed is calculated in the method to achieve an optimum titrant consumption of 6 mL.
- The back titration is performed using a DMi140-SC redox sensor with cerium(IV) sulfate 0.01 mol/l.
Remarks
1. Pure gold is used as a standard.
2. Theoretical consumption: - 20 mg gold corresponds to 7.5 mL
hydroquinone, c(1/2 C6H6O2)=0.05 mol/L, and 7.0 mL cerium sulfate, c(Ce(SO4)2)=0.01 mol/L.
- 1 mL hydroquinone c c(1/2 C6H6O2)=0.05 mol/L corresponds to 5 mL cerium sulfate, c(Ce(SO4)2)= 0.01 mol/L.
Literature: METTLER TOLEDO Application Brochure “Gold and Silver”, ME-724613, 04/1994.
Sample Gold, 20-30 mg
Compound Gold, Au M(Au) = 196.967 g/mol, z = 3
Chemicals 32% hydrochloric acid, HCl 65% nitric acid, HNO3 0.1 mol/L hydrochloric acid, HCl
Titrant Hydroquinone, C6H6O2 c(1/2 C6H6O2) = 0.05 mol/L Cerium sulfate, Ce(SO4)2 c(Ce(SO4)2) = 0.01 mol/L
Standard See M297 and M298 for standardization of titrants
Indication DMi140-SC (Pt ring) combined redox electrode
Chemistry Reduction with hydroquinone: 2Au3+ + 3C6H6O2 → 2Au + 6H+ + 3C6H4O2
Titration of excess hydroquinone: C6H6O2 + 2Ce4+ → C6H4O2 + 2Ce3+ + 2H+
Calculation Content (%): R1= 100*(QENDDi*H[Titer 1/2 C6H6O2 vs gold]-Q*H[Titer Ce(SO4)2 vs gold])*C
C = M/(m*z*1000) Content (carat): R2= 24*(QENDi*H[Titer ½ C6H6O2 vs gold]-Q*H[Titer Ce(SO4)2 vs gold])*C
C = M/(m*z*1000)
Waste disposal
HCl/HNO3: Neutralization with NaOH Hydroquinone: Evaporate solution,special waste Cerium: Precipitate with NaOH, filtrate, special waste Gold: Filtrate solution, special waste
Author, Version
Claudia Schreiner, MSG Anachem, April 2007
METTLER TOLEDO Page 1 of 6 Titration Application M299-2007
Instruments - T90 Titration Excellence with LabX titration - XS205 Balance
Other titrators: This method can be also run with the T50 and T70 Titration Excellence (if the logical conditions are eliminated), and with the DL5x and DL7x instruments (with major changes).
Accessories - 2 x 10 mL DV1010 burettes - Additional dosing unit ME-51109030 - Glass titration beaker ME-101446 - SP250 Peristaltic pump ME-5108016
Results Start time: 27.03.2007
Sample Data Note / ID Sample size Correction factor
No. 1/3 Gold 995 0.01968 g 100
No. 2/3 Gold 995 0.02061 g 100
No. 3/3 Gold 995 0.02673 g 100
Results Note / ID Rx Result Unit
No. 1/3 Gold 995 R1= 99.958 %
R2= 23.990 Carat
No. 2/3 Gold 995 R1= 98.819 %
R2= 23.717 Carat
No. 3/3 Gold 995 R1= 99.161 %
R2= 23.799 Carat
Statistics
Rx Name n Mean Value Unit s srel[%]
R1 Purity 3 99.31 % 0.59 0.6
R2 Carat 3 23.84 Carat 0.14 0.6
Titration curve
sample 1/3
METTLER TOLEDO Page 2 of 6 Titration Application M299-2007
METTLER TOLEDO Page 3 of 6 Titration Application M299-2007
Table of measured values Volume lncrement Signal Change 1. Derivative Time mL mL mV mV mV/mL s 0 NaN 471.9 NaN NaN 0 0.005 0.005 471.7 -0.2 NaN 3 0.01 0.005 471.7 0 NaN 6 0.022 0.012 471.7 0 NaN 9 0.054 0.032 471.7 0 NaN 12 0.131 0.077 471.9 0.2 1.9 15 0.325 0.194 472.4 0.5 2.68 18 ... ... ... ... ... ... 3.925 0.2 487.2 1.2 7.02 73 4.125 0.2 488.7 1.5 7.67 76 4.325 0.2 490.5 1.8 8.48 79 4.525 0.2 492.2 1.7 9.47 82 4.725 0.2 494.2 2 10.59 86 4.925 0.2 496.6 2.4 10.94 89 5.125 0.2 499.4 2.8 0.34 92 5.325 0.2 502.9 3.5 11.09 96 5.525 0.2 507.3 4.4 73.22 99 5.725 0.2 513.8 6.5 264.75 102 5.925 0.2 527.1 13.3 797.13 105 5.998 0.073 596.2 69.1 1429.05 135 6.0024 NaN 644.4 NaN NaN NaN 6.003 0.005 651 54.8 1748.07 166 6.008 0.005 694.4 43.4 1315.63 196 6.013 0.005 720.7 26.3 1739.01 226 . . . . . . . . . . . . . . . . . . 13.915 0.2 887.4 0.7 2.85 451 14.115 0.2 887.8 0.4 2.8 454 14.315 0.2 888.4 0.6 NaN 457 14.515 0.2 889 0.6 NaN 460 14.715 0.2 889.4 0.4 NaN 463 14.915 0.2 890.4 1 NaN 466 15.0 0.085 890.4 0 NaN 469 sample 1/3
Comments
Principle: To determine pure gold or its content in alloys the precipitation method with hydroquinone has been selected. Most of the associated metals do not interfere with the determination. As the precipitation of gold is too slow to execute a direct titration with hydroquinone, an excess of hydroquinone is added to the dissolved gold. The excess is titrated back with cerium sulfate:
1. Oxidation of gold: Gold is oxidized to Au3+ by aqua regia (conc. HCl:conc. HNO3 3:1 v/v). 2. Precipitation of gold:
Au3+ is reduced by excess hydroquinone and precipitates, and quinone is formed. Au3+ + 3 C6H6O2 → 2 Au + 3 C6H4O2 + 6 H+
3. Excess hydroquinone is oxidized by cerium(IV) sulfate (back titration): 2 Ce4+ + C6H6O2 → C6H4O2 + 2 Ce3+ + 2 H+
It has been shown (Ref. 1) that copper, iron, zinc, nickel, platinum and palladium do not interfere. We have found in our own work that silver does not interfere.
Application M297 (Factor cerium(IV) sulfate vs. hydroquinone) and M298 (Titer of hydroquinone and cerium(IV) sulfate with pure gold) describe the standardization of the used reagents. The complete analysis sequence involves the following steps: 1) M297 2) M298 3) M299
Accuracy: The accuracy which can be obtained by these methods depends on:
1. the weighing and handling procedures e.g. use a balance with high resolution and tweezers 2. the care with which the gold sample is prepared and dissolved. 3. the amount of gold taken. 4. the accuracy of titration method and titrator.
Maintenance of the electrode: We recommend to always clean the electrode after 6 gold titrations because gold contaminates the platinum ring by forming a thin layer: Place it for two minutes in aqua regia and rinse thoroughly with deionized water (See also leaflet of the DMi140-SC sensor).
Literature: 1. S.C. Soundar Rajan and N. Appala Raju, “Titrimetric Determination of Gold by Precipitation with
Hydroquinone”, Talanta 22 (1975), pp. 185-189. 2. A. Chow, “The Stability of Gold Solutions”, Talanta 18 (1971), pp. 453-456.
Principle of titration method
002 Sample The known gold concentration (in % or in carat) is entered as factor f of the sample in method function 002 SAMPLE. It will be used in the function 004 (or 005) AUXILIARY VALUE. 004 Auxiliary Value / 005 Auxiliary Value In this function the factor of the method function 002 Sample will be used to calculate the H[Fraction Gold] depending on the content of the alloy. 008 Dispense Hydroquinone An excess of hydroquinone is dispensed depending on the amount of gold sample and concentration. Furthermore, the dispensed volume (VENDDi) is calculated for an optimum titrant consumption of 6 mL cerium(IV) sulfate for the back titration.
METTLER TOLEDO Page 4 of 6 Titration Application M299-2007
Principle of titration method
011 Calculation Purity (percent) The concentration is calculated in percent. 012 Calculation Purity (carat) The concentration is calculated in carat.
Parameter Symbol Unit Predispense Cerium sulfate VENDDi [mL] Predispense Cerium sulfate QENDDi [mmol] Consumption Cerium sulfate Q [mmol] Equivalent number of gold z 3 Size of gold sample m [g] Molar mass of gold [g/mol] M 196.967 Titrant Cerium(IV) sulfate[mol/L] c (Ce(SO4)2) 0.01 Titrant Hydroquinone [mo/L] c (½ C6H6O2) 0.05 Correction factor f % or carat gold of the
sample
METTLER TOLEDO Page 5 of 6 Titration Application M299-2007
METTLER TOLEDO Page 6 of 6 Titration Application M299-2007
Method 001 Title
Type General titration
Compatible with T90
ID m299
Title Gold content
Author Mettler Toledo
Date/Time 21.03.2007 16:02:39
Modified at 05.04.2007 10:41:10
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Gold 995
Entry type Weight
Lower limit 0.02 g
Upper limit 0.03 g
Density 1.0 g/mL
Correction factor 24.0
Temperature 25.0°C
Entry Arbitrary
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Auxiliary value
Name Fraction Gold
Formula H= f/24
Limits No
Condition Yes
Formula f<=24
005 Auxiliary value
Name Fraction Gold
Formula H= f/100
Limits No
Condition Yes
Formula f>24ANDf<=100
006 Pump
Auxiliary reagent HCl 0.1 mol/L
Volume [mL] 30
Condition No
007 Stir
Speed 50%
Duration 5 s
Condition No
008 Dispense
Titrant ½ C6H6O2
Concentration 0.05 mol/L
Volume 1.2*H[Titer Ce(SO4)2 vs. gold]
+304.6*m*H[Fraction Gold]/H[Titer
½ C6H6O2 vs. gold]
Dosing rate 60.0 mL/min
Condition No
009 Stir
Speed 50%
Duration 180 s
Condition No
010 Titration (EQP) [1]
Titrant
Titrant Ce(SO4)2
Concentration 0.01 mol/L
Sensor
Type mV
Sensor DM140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 40%
Predispense
Mode None
Waiting time 0 s
Control
Control User
Titrant addition Dynamic
dE (set value) 8 mV
dV (min) 0.005 mL
dV (max) 0.2 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 200
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 15 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating
Accompanying stating No
Condition
Condition No
011 Calculation R1
Result Purity
Result unit %
Formula R1=
100*(QENDDi*H[Titer 1/2 C6H6O2 vs.
gold]-Q*H[Titer Ce(SO4)2 vs.
gold])*C
Constant C= M/(m*z*1000)
M M[Gold]
z z[Gold]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
012 Calculation R2
Result Purity in Carat
Result unit Carat
Formula R2=
24*(QENDDi*H[Titer 1/2 C6H6O2 vs
gold]-Q*H[Titer Ce(SO4)2 vs.
gold])*C
Constant C= M/(m*z*1000)
M M[Gold]
z z[Gold]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
013 End of sample
Note:
1. The method can be easily modified to be run on T50 and
T70 Titration Excellence instruments:
delete method functions 004 and 005 AUXILIARY VALUE
since they contain logical conditions.
2. If the gold content is known (% or carat), then it can
be entered as a factor in the method function SAMPLE. In
this way, it is possible to calculate the most
appropriate predispense for an optimum consumption of 6
mL.
METTLER TOLEDO Application M195-2010
Determination of Silver in Silver Alloys Content determination of silver Ag(I) in silver alloys by precipitation silver chloride AgCl with sodium chloride as a titrant. The titration is monitored with a combined silver ring electrode.
Preparation and Procedures CAUTION: Work in a fume hood. Concentrated nitric acid is dangerous. Use safety googles, wear gloves and a lab coat.
Sample preparation:
- Clean the sample with acetone and let it dry – use tweezers.
- Weigh in a sample corresponding to approx. 40 mg Ag and read to ±0.01 mg; then put it in the glass titration beaker.
- Add 3 mL of 33% HNO3 and warm up to 60 °C in a water bath until the sample is completely dissolved.
- In case of an impure sample add 1 mL of H2SO4 to improve the dissolution.
- Let the sample cool down to room temperature. This procedure is a prerequisite to achieve high precision.
Titration:
- Add 50 mL deionized water.
- Start titration. The titration is performed using a DM141-SC silver ring electrode with sodium chloride 0.1 mol/l.
Remarks
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- Rinse the electrode after each sample. If necessary, clean the metal ring of the electrode with a paper tissue at the end of each sample series.
- High speed: The method was also streamlined to fast titrations. The titration takes less than 2 min.
Literature: - METTLER TOLEDO Application Brochure No. 28
“Electronics and Electroplating Applications”, 2007 (only available as PDF-file).
- Vogel's textbook of quantitative inorganic analysis, 4th edition, Longman Group Limited, 1978.
Sample Silver alloys, approx. 0.05 g
Compound Silver, Ag M = 107.868; z = 1
Chemicals 3 mL 33% nitric acid, HNO3
50 mL deionized water (conc. sulfuric acid)
Titrant Sodium chloride, NaCl, c(NaCl) = 0.1 mol/L
Standard Silver nitrate, AgNO3 See e.g. M536
Indication DMi141-SC (Ag ring) combined metal electrode
Chemistry Precipitation of silver chloride: Ag+ + Cl- → AgCl
Calculation Content (%):
R = Q*C/m
C = M/(10*z)
Waste disposal
Silver precipitate can be separated (filtration). The filtrated solution is neutralized with NaOH.
Author, Version
Susanne Wahlen, MSG Anachem, May 2010
METTLER TOLEDO Page 1 of 4 Titration Application M195-2010
Instruments - T50/70/90 Titration Excellence - XS205 Balance This method can also be run with the G20 Compact Titrator (with minor adjustments)
Accessories - 2 x 10 mL DV1010 burette - 1 x additional dosing unit - Glass titration beaker ME-101446 - LabX titration pro
Results METTLER TOLEDO T90
DL90 Silver
Method: MS112B Silver sample 04.06.2010 15:14:54
Results
Series start time 04.06.2010 15:15:25
No. Note / ID Start time Rx Result Unit Name
1/8 C6: Silver Sample 04.06.2010 15:15:25 R1 = 3.447 mL Consumption
R2 = 98.077(2)% Silver Content
2/8 C6: Silver Sample 04.06.2010 15:19:07 R1 = 3.476 mL Consumption
R2 = 98.912 % Silver Content
3/8 C6: Silver Sample 04.06.2010 15:22:02 R1 = 3.476 mL Consumption
R2 = 98.907 % Silver content
4/8 C6: Silver Sample 04.06.2010 15:25:29 R1 = 3.477 mL Consumption
R2 = 98.915 % Silver Content
5/8 C6: Silver Sample 04.06.2010 15:28:38 R1 = 3.479 mL Consumption
R2 = 98.972 % Silver Content
6/8 C6: Silver Sample 04.06.2010 15:31:52 R1 = 3.480 mL Consumption
R2 = 99.018 % Silver Content
7/8 C6: Silver Sample 04.06.2010 15:35:37 R1 = 3.479 mL Consumption
R2 = 98.986 % Silver Content
8/8 C6: Silver Sample 04.06.2010 15:39:03 R1 = 3.480 mL Consumption
R2 = 99.024 % Silver Content
Statistics: n = 7 R2 = 98.962 ± 0.051% s = 0.300 srel: 0.051% (2) excluded
Titration curve
Sample 1/8
METTLER TOLEDO Page 2 of 4 Titration Application M195-2010
METTLER TOLEDO Page 3 of 4 Titration Application M195-2010
Table of measured values
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL min:s -------------------------------------------------------------------------------------------- 0 NaN 415.2 NaN NaN 0 1.143 1.143 403.6 -11.6 NaN 4 1.7145 0.5715 396.3 -7.3 NaN 7 2 0.2855 391.5 -4.8 NaN 10 2.4 0.4 382.8 -8.7 NaN 24 2.8 0.4 370.3 -12.5 -50.52 27 3.01 0.21 360.4 -9.9 -74.7 30 3.1355 0.1255 352.6 -7.8 -101.94 34 3.244 0.1085 342.3 -10.3 -143.19 37 3.3075 0.0635 333.7 -8.6 -195.41 40 3.353 0.0455 326.7 -7 -263.64 43 3.4045 0.0515 313 -13.7 -396.33 46 3.424 0.0195 305.2 -7.8 -496.98 49 3.439 0.015 297.4 -7.8 -578.52 52 3.452 0.013 289.7 -7.7 -655 55 3.4655 0.0135 279.2 -10.5 -740.15 58 3.4745 0.009 271.2 -8 -833.6 62 EQP1 3.47658 NaN 269.4 NaN -833.98 NaN 3.4835 0.009 263.4 -7.8 -816.06 65 3.494 0.0105 254.2 -9.2 -724.07 68 3.5045 0.0105 246.1 -8.1 -643.32 71 3.518 0.0135 237.9 -8.2 -570.06 74 3.5365 0.0185 229.4 -8.5 NaN 77 3.562 0.0255 220.4 -9 NaN 80 3.596 0.034 212 -8.4 NaN 83 3.6465 0.0505 203 -9 NaN 86 3.7185 0.072 194.6 -8.4 NaN 89
Comments
- To further improve accuracy and precision, it is recommended to use a microbalance.
- Furthermore, the sample has to be cleaned using e.g. ethanol, acetone and additional suitable organic solvents to eliminate impurities such as e.g. fatty residues.
- The sample has to be handled using cleaned tweezers in order to avoid any contact with the fingers (fatty residues).
- In this application, the sample i.e. the digested silver solution was dispensed with an additional dosing unit in order to achieve a higher repeatability (m = 7 mL).
METTLER TOLEDO Page 4 of 4 Titration Application M195-2010
Method 001 Title Type General titration Compatible with T50 / T70 / T90 ID MS112B Title Silver Sample Author wahlen Date/Time 03.06.2010 13:44:05 Modified at 04.06.2010 15:14:54 Modified by wahlen Protect No SOP None 002 Sample Number of IDs 1 ID 1 Silver wire Entry type Fixed weight Weight [g] 0.037837 Density [g/mL] 1.0 Correction factor 1.0 Temperature [°C] 25.0 Entry Arbitrary 003 Titration stand (Manual stand) Type Manual Stand Titration stand Manual Stand 1 004 Stir Speed [%] 40 Duration [s] 1 Condition No 005 Dispense (normal)[1] Titrant Silver sample Concentration 99.9 Volume [mL] 7.0 Dosing rate [mL/min] 60.0 Condition No 006 Stir Speed [%] 40 Duration [s] 10 Condition No 007 Titration (EQP) [1] Titrant Titrant NaCl Concentration [mol/L] 0.1 Sensor Type mV Sensor DM141-SC Unit mV Temperature acquisition Temperature acquisition No Stir Speed [%] 30 Predispense Mode Volume Volume [mL] 2 Waiting time 10 Control Control Normal Mode Precipitation Show parameters Yes Titrant addition Dynamic dE (set value) [mV] 9.0 dV (min) [mL] 0.008 dV (max) [mL] 0.4 Mode Equilibrium controlled dE [mV] 0.5 dt [s] 1.0 t (min) [s] 3.0 t (max) [s] 30 Evaluation and recognition Procedure Standard Threshold 400.0 Tendency None Ranges 0 Add. EQP criteria No Termination At Vmax [mL] 10.0 At potential No At slope No After number of recognized EQPs Yes Number of EQPs 1 Combined termination criteria No Accompanying stating Accompanying stating No Condition Condition No 008 Calculation R1 Result Consumption Result unit mL Formula R1=VEQ Constant C= 1 M M[None] z z[None] Decimal places 3
Result limits No Record statistics No Extra statistical func. No Send to buffer No Condition No 009 Calculation R2 Result Silver Content Result unit % Formula R2=Q*C/m Constant C= M/(10*z) M M[Silver] z z[Silver] Decimal places 3 Result limits No Record statistics Yes Extra statistical func. No Send to buffer No Condition No 010 Record Summary No
Results Per sample
Raw results Per sample
Table of meas. values Last titration function
Sample data No
Resource data No
E - V Last titration function
dE/dV - V Last titration function
log dE/dV - V No
d2E/dV2 - V No
BETA – V No
E - t No
V - t No
dV/dt - t No
T – t No
E – V & dE/dV – V No
V – t & dV/dt – t No
Method No
Series data No
Condition No
011 End of sample
METTLER TOLEDO Application M196-2010
Determination of Free Cyanide in a Cyanidic Silver Bath Free cyanide is precipitated by addition of silver nitrate forming silver dicyanoargentate. The titration is indicated by a silver ring sensor.
Preparation and Procedures CAUTION: Cyanide is toxic!
A too low pH value i.e. below pH 3 leads to the formation of HCN gas which is toxic. Thus, work in a fume hood, use safety googles and wear gloves.
Sample preparation:
- 1 mL silver bath is diluted with 50 mL deionized water.
Titration:
- Start titration. The titration is performed using a DM141-SC silver ring electrode with silver nitrate 0.1 mol/l.
Remarks
- The method was developed on a DL67 titrator and has been adapted for T50/T70/T90 Titration Excellence and G20 Compact Titrator.
Literature:
- METTLER TOLEDO Application Brochure No. 28 “Electronics and Electroplating Applications”, 2007 (only available as PDF-file).
- Application note, DL25 Application Brochure "Petroleum and electroplating", ME-51724627.
- Vogel's textbook of quantitative inorganic analysis, 4th edition, Longman Group Limited, 1978.
- D.A. Skoog, D.M. West, "Fundamentals of Analytical Chemistry", Holt, Rinehart, and Winston, 1969.
- See Application M525 (Brochure 18) for the standardization of silver nitrate.
Sample Silver bath, 1 mL
Compound Potassium cyanide, KCN M = 65.12, z = 1
Chemicals 50 mL deionized water,
Titrant Silver nitrate, c(AgNO3) = 0.1 mol/L
Standard Sodium chloride, NaCl See e.g. M525
Indication DMi141-SC (Ag ring) combined metal sensor
Chemistry Ag+ + 2 CN- → Ag(CN)2-
First silver excess (precipitate): Ag+ + Ag(CN)2
- → Ag[Ag(CN)2]
Calculation Content (g/L):
R = Q*C/m
C = M*2
The content is expressed as KCN g/L
Waste disposal
Cyanide waste. CAUTION: Cyanide is toxic!
Author, Version
Application laboratory, MT-D, 1994 Rev. February 2010 / C. De Caro
METTLER TOLEDO Page 1 of 4 Titration Application M196-2010
Instruments - DL67 Version 3.1 - Balance, e.g. XS205 - Sample changer, e.g. Rondo20
Other titrators: This method can also be run with the T50/T70/T90 Titration Excellence and G20 Compact Titrator (delete “Rinse” function), and with the DL5x and DL7x instruments.
Accessories - 10 mL DV1010 burettes - PP titration beaker ME-101974 - SP250 Peristaltic pump ME-51108016 - Printer
Results Method BL20 KCN im cy.Ag.Bad 17-02-1994 10:46 User Measured 24-02-1994 14:49 RESULTS No ID1 ID2 Sample amount and results 1/1 1.0 mL Fixed volume U R1 = 110.34 g/L KCN R2 = 8.49 mL Consumption 1/2 1.0 mL Fixed volume U R1 = 111.64 g/L KCN R2 = 8.59 mL Consumption 1/3 1.0 mL Fixed volume U R1 = 114.09 g/L KCN R2 = 8.78 mL Consumption STATISTICS Number results R1 n = 3 Mean value x = 112.02 g/L KCN
Titration curve
METTLER TOLEDO Page 2 of 4 Titration Application M196-2010
METTLER TOLEDO Page 3 of 4 Titration Application M196-2010
Table of measured values Not available
Comments
• A soluble complex Ag(CN)2- is first formed by the reaction between silver and cyanide ion:
Ag+ + 2 CN- → Ag(CN)2–
• As long as free cyanide is still present, the solution remains clear, but the first excess of silver causes formation of a white precipitate silver dicyanoargentate that indicates the endpoint:
Ag+ + Ag(CN)2- → Ag[Ag(CN)2]
• Since 1 mole of Ag ions reacts with two moles of cyanide ions, the factor 2 is taken into account in the calculation (see constant C).
• T50/70/90 Titration Excellence –G20 Compact Titrator No titration method function “Rinse” can be defined when working with the G20 Compact Titrator. Thus, function 006 “Rinse” has to be deleted in order to run the analysis on the G20 titrator.
METTLER TOLEDO Page 4 of 4 Titration Application M196-2010
Method DL7x Titrators:
Title
Method ID ........................... BL20
Title ............................... KCN im cy.Ag.Bad
Date/time ........................... 17-02-1994 10:46
Sample
Number samples ...................... 20
Titration stand ..................... ST20 1
Entry type .......................... Fixed volume
Volume [mL]....................... 1.0
ID1 .................................
Molar mass M ........................ 65.12
Equivalent number z ................ 1
Temperatur sensor ................... Manual
Stir
Speed [%] ........................... 50
Time [s] ............................ 10
Titration
Titrant ............................. AgNO3
Concentration [mol/L] ............... 0.1
Sensor .............................. DM141-SC
Unit of meas. ...................... mV
Titration mode ...................... EQP
Predispensing 1................... to volume
Volume [mL] .................... 1.0
Titrant addition .................... DYN
dE(set) [mV] ................... 8.0
Limits dV ...................... Absolute
dV(min) [mL]................. 0.05
dV(max) [mL]................. 0.5
Measure mode ....................... EQU
dE [mV] ........................ 0.5
dt [s] ......................... 1.0
t(min) [s] ..................... 3.0
t(max) [s] ..................... 30.0
Threshold ........................... 50.0
Maximum volume [mL] ................. 30.0
Termination after n EQPs ............ Yes
n = ........................... 1
Evaluation procedure ................ Standard
Rinse
Auxiliary reagent ................... H2O
Volume [mL] ......................... 10.0
Calculation
Result name ......................... KCN
Formula ............................ R=Q*C/m
Constant ............................ C=M*2
Result unit ......................... g/L
Decimal places ...................... 2
Calculation
Result name ......................... Comnsumption
Formula ............................ R2=VEQ
Constant ............................
Result unit ......................... mL
Decimal places ...................... 2
Statistics
Ri (i=index) ........................ R1
Standard deviation s ............... Yes
Rel. standard deviation srel ........ Yes
Outlier test ........................ Yes
Record
Output unit ......................... Printer
All results ......................... Yes
Titration Excellence:
001 Title
Type General titration
Compatible with T50/T70/T90
ID m196
Title KCN im cy.Ag.Bad
Author Mettler Toledo
Date/Time 01.02.2010 08:00:00
Modified at 01.02.2010 08:00:10
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 KCN in cyanidic Ag bath
Entry type Fixed volume
Volume 1.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Arbitrary
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Stir
Speed 50%
Duration 10 s
Condition No
005 Titration (EQP) [1]
Titrant
Titrant AgNO3
Concentration 0.1 mol/L
Sensor
Type mV
Sensor DMi141-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 1.0
Waiting time 10 s
Control
Control User
Titrant addition Dynamic
dE(set value) 8.0 mV
dV(min) 0.05 mL
dV(max) 0.5 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 1 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 50
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 30 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
006 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. Per cycle 10 ml
Position Current position
007 Calculation R1
Result KCN in cyan. Ag-bath
Result unit g/L
Formula R1=Q*C/m
Constant C= M*2
M M[KCN]
z z[KCN]
Decimal places 2
Result limits No
Record statistics Yes
. . .
008 End of sample
009 Report
Summary Yes
. . .
METTLER TOLEDO Application M465-2010
Determination of Free Cyanide and Silver Free cyanide and silver are precipitated as silver dicyanoargentate by addition of silver nitrate; the titration is indicated by a silver ring sensor.
Preparation and Procedures CAUTION: Cyanide is very toxic!
A too low pH value i.e. below pH 3 leads to the formation of HCN gas which is toxic. Thus, work only in a fume hood, use safety goggles, wear gloves and a lab coat.
1) The titer determination of silver nitrate is performed using sodium chloride (NaCl) as a primary standard. Since small amounts of salt cannot be weighed in exactly, it is recommended to prepare an aqueous solution of NaCl, and then to add the standard with a pipette.
2) 1-2 mL of silver bath is pipetted in a plastic titration beaker, 50 mL deionized water is automatically added with the diaphragm pump of the Rondo sample changer.
3) The titration is performed using a DMi141-SC silver ring electrode with ½ AgNO3 0.2 mol/l.
4) During titration, the pH is maintained at 12.5 with NaOH using the parameter “Accompanying stating”.
Note: The parameters have been optimized for this specific sample. It may be necessary to adapt the method to your sample.
Remarks
Literature:
- METTLER TOLEDO Application Brochure No. 28 “Electronics and Electroplating Applications”, 2007 (only available as PDF-file).
- Application M196, “Determination of Free Cyanide in a Cyanidic Silver Bath”.
- Vogel's textbook of quantitative inorganic analysis, 4th edition, Longman Group Limited, 1978.
- D.A. Skoog, D.M. West, "Fundamentals of Analytical Chemistry", Holt, Rinehart, and Winston, 1969.
- See Application M525 (Brochure 18) for the standardization of silver nitrate.
Sample Silver cyanidic bath with approx. 8-10 g/L CN- and approx. 20-25 g/L Ag+, 0.5-2 mL
Compound Cyanide, CN- M = 26.02 g/mol, z = 1 Silver, Ag+
M = 107.868 g/mol, z = 2
Chemicals 50 mL deionized water
Titrant Silver nitrate, AgNO3 c(½ AgNO3) = 0.2 mol/L 1 mL≙ 2.60 mg CN-, 1 mL≙5.39 mg Ag+ Sodium hydroxide, NaOH, C(NaOH) = 1 mol/L
Standard Sodium chloride, NaCl
Indication DMi141-SC (Ag ring) DGi112-Pro
Chemistry Ag+ + 2 CN- → Ag(CN)2-
First silver excess (precipitate): Ag+ + Ag(CN)2
- → Ag[Ag(CN)2]
Calculation R1 = Q[2]*C/m C = M/z Content expressed as CN- g/L R2 = (QEX[2]+Q[3]-Q[2])*C/m C = M/z Content expressed as Ag+ in g/L
Waste disposal
Cyanide waste, pH >12 CAUTION: Cyanide is toxic!
Author, Version
Claudia Schreiner, MSG Anachem June 2010
METTLER TOLEDO Page 1 of 5 Titration Application M465-2010
Instruments - T90 Titration Excellence - Balance, e.g. XS205 - Rondo 20 Sample Changer with PowerShower™ and diaphragm pump
Accessories - 2 x 10 mL DV1010 burettes - 1 additional dosing Unit - PP titration beaker ME-101974 - SP250 Peristaltic pump ME-51108016
Results All results Sample Cyanide and Silver Bath (1/6) R1 (Cyanide content) 9.96 R2 (Silver content) 22.69 Sample Cyanide and Silver Bath (2/6) R1 (Cyanide content) 9.89 R2 (Silver content) 22.82 Sample Cyanide and Silver Bath (3/6) R1 (Cyanide content) 9.86 R2 (Silver content) 22.80 Sample Cyanide and Silver Bath (4/6) R1 (Cyanide content) 9.85 R2 (Silver content) 22.82 Sample Cyanide and Silver Bath (5/6) R1 (Cyanide content) 9.73 R2 (Silver content) 23.18 Sample Cyanide and Silver Bath (6/6) R1 (Cyanide content) 9.74 R2 (Silver content) 23.05 Statistics R1 Cyanide content R2 Silver content Samples 6 Samples 6 Mean 9.84 Mean 22.89 s 0.09 s 0.18 srel 0.9% srel 0.80%
Titration curve
Cyanide Silver
METTLER TOLEDO Page 2 of 5 Titration Application M465-2010
METTLER TOLEDO Page 3 of 5 Titration Application M465-2010
Table of measured values
Values Cyanide determination
Volume Increment Signal Change 1st deriv. Time Temperature mL mL mV mV mV/mL s °C 0.000 NaN -197.6 NaN NaN 0 25 0.050 0.05 -167.1 30.5 NaN 10 25 0.100 0.05 -168.1 -1.0 NaN 20 25 0.225 0.13 -168.2 -0.1 NaN 30 25 0.425 0.20 -168.2 0.0 NaN 40 25 0.625 0.20 -168.3 -0.1 -2.6 50 25 0.825 0.20 -168.0 0.3 1.8 61 25 1.025 0.20 -167.6 0.4 2.2 71 25 1.225 0.20 -167.1 0.5 2.6 81 25 1.425 0.20 -166.5 0.6 3.0 91 25 . . . . . . . . . . . . . . . . . . . . . 7.806 0.05 -79.7 5.0 104.6 474 25 7.856 0.05 -73.4 6.3 184.4 484 25 7.906 0.05 -65.3 8.1 308.6 494 25 7.956 0.05 -53.1 12.2 286.5 504 25
EQP1 7.985 NaN -40.5 NaN 325.3 NaN NaN 8.006 0.05 -31.5 21.6 221.5 516 25 8.056 0.05 2.1 33.6 193.3 539 25 8.106 0.05 5.6 3.5 177.2 549 25 8.231 0.13 8.1 2.5 NaN 559 25 8.431 0.20 9.2 1.1 NaN 570 25 8.631 0.20 9.6 0.4 NaN 580 25 8.831 0.20 9.9 0.3 NaN 590 25 9.031 0.20 10.1 0.2 NaN 600 25
Values Silver determination
Volume Increment Signal Change 1st deriv. Time Temperature mL mL mV mV mV/mL s °C 0 NaN -197.6 NaN NaN 0 25 0.05 0.05 -167.1 30.5 NaN 10 25 0.1 0.05 -168.1 -1 NaN 20 25 0.225 0.125 -168.2 -0.1 NaN 30 25 0.425 0.2 -168.2 0 NaN 40 25 0.625 0.2 -168.3 -0.1 -2.63 50 25 0.825 0.2 -168 0.3 1.77 61 25 . . . . . . . . . . . . . . . . . . . . . 7.8555 0.05 -73.4 6.3 184.36 484 25 7.9055 0.05 -65.3 8.1 308.59 494 25 7.9555 0.05 -53.1 12.2 286.5 504 25 EQP1 7.984614 NaN -40.5 NaN 325.27 NaN NaN 8.0055 0.05 -31.5 21.6 221.47 516 25 8.0555 0.05 2.1 33.6 193.33 539 25 8.1055 0.05 5.6 3.5 177.24 549 25 8.2305 0.125 8.1 2.5 NaN 559 25 8.4305 0.2 9.2 1.1 NaN 570 25 8.6305 0.2 9.6 0.4 NaN 580 25 8.8305 0.2 9.9 0.3 NaN 590 25 9.0305 0.2 10.1 0.2 NaN 600 25
METTLER TOLEDO Page 4 of 5 Titration Application M465-2010
Comments
Reaction
A soluble complex Ag(CN)2- is first formed by the reaction between silver and cyanide ion:
Ag+ + 2 CN- → Ag(CN)2–
As long as free cyanide is still present, the solution remains clear, but the first excess of silver
causes formation of the white precipitate silver dicyanoargentate that indicates the endpoint:
Ag+ + Ag(CN)2- → Ag[Ag(CN)2]
Method
The titration of cyanide and silver is a two step procedure. The first step (Titration [2]) determines the cyanide content by using an asymmetric evaluation of the curve.
The second step (Titration [3]) determines the silver content using a standard evaluation of the curve.
Method 001 Title
Type General titration
Compatible with T90
ID CSM196
Title Cyanide and Silver Bath
Author Mettler Toledo
Date/Time 01.06.2010 14:55:13
Modified at 01.06.2010 16:59:58
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Silver bath
Entry type Volume
Lower limit 0.0 mL
Upper limit 5.0 mL
Volume 1.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Arbitrary
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Pump
Auxiliary reagent WATER
Volume 50 mL
Condition No
005 Stir
Speed 35%
Duration 10 s
Condition No
006 Measure
Sensor
Type pH
Sensor DG112-Pro
Unit pH
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Acquisition of measured values
Acquisition Equilibrium
dE 0.5 mV
dt 1 s
t (min) 10 s
t (max) 30
Mean value No
Condition
Condition No
007 Calculation R1
Result pH
Result unit
Formula R1 = E
Constant C= M/z
M M[None]
z z[None]
Decimal places 2
Result limits No
Record statistics No
Extra statistical funct. No
Send to buffer No
Condition No
008 Titration (EP) [1]
Titrant
Titrant NaOH
Concentration 1.0 mol/L
Sensor
Type pH
Sensor DG112-Pro
Unit pH
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode None
Waiting time 10 s
Control
Control Absolute
Tendency None
End point value 12.5 pH
Control band 0.5 pH
Dosing rate (max) 10 mL/min
Dosing rate (max) 10 mL/min
Termination
At EP Yes
Termination delay 10 s
At Vmax 20 mL
Max Time 600s
Accompanying stating
Accompanying stating No
Condition
Condition Yes
Formula R1<12.3
METTLER TOLEDO Page 5 of 5 Titration Application M465-2010
009 Titration (EQP) [2]
Titrant
Titrant ½ AgNO3
Concentration 0.2 mol/L
Sensor
Type mV
Sensor DM141-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 0.5
Waiting time 10 s
Control
Control User
Titrant addition Dynamic
dE(set value) 4.0 mV
dV(min) 0.005 mL
dV(max) 0.1 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 10 s
t (max) 30 s
Evaluation and recognition
Procedure Asymmetric
Threshold 200
Tendency Positive
Ranges 1
Lower limit -400 mV
Upper limit 150 mV
Add. EQP criteria No
Termination
At Vmax 5 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating
Accompanying stating Yes
Titrant
Titrant NaOH
Concentration 1.0 mol/L
Continuous addition No
Sensor
Type pH
Name DG112-Pro
Unit pH
Pretitration
Pretitration No
Predispense
Mode None
Wait time 0 s
Control
Set potential 12.5 pH
Control band 0.5 pH
Tendency Positive
Dosing rate (max) 10 mL/min
Dosing rate (min) 10 µL/min
Monitoring
Monitoring No
Condition
Condition No
010 Titration (EQP) [3]
Titrant
Titrant ½ AgNO3
Concentration 0.2 mol/L
Sensor
Type mV
Sensor DM141-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode None
Waiting time 0 s
Control
Control User
Titrant addition Dynamic
dE(set value) 4.0 mV
dV(min) 0.05 mL
dV(max) 0.2 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 2 s
t (min) 10 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 100
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 10 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Accompanying stating
Accompanying stating Yes
Titrant
Titrant NaOH
Concentration 1.0 mol/L
Continuous addition No
Sensor
Type pH
Name DG112-Pro
Unit pH
Pretitration
Pretitration No
Predispense
Mode None
Wait time 0 s
Control
Set potential 12.5 pH
Control band 0.5 pH
Tendency Positive
Dosing rate (max) 10 mL/min
Dosing rate (min) 10 µL/min
Monitoring
Monitoring No
Condition
Condition No
011 Calculation R2
Result Cyanide content
Result unit g/L
Formula R2 = Q[2]*C/m
Constant C= M/z
M M[Cyanide]
z z[Cyanide]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical funct. No
Send to buffer No
Condition No
012 Calculation R3
Result Silver content
Result unit g/L
Formula R3 = (QEX[2]+Q[3]-Q[2])*C/m
Constant C= M/z
M M[Silver]
z z[Silver]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical funct. No
Send to buffer No
Condition No
013 Rinse
Auxiliary reagent WATER
Rinse cycles 3
Vol. Per cycle 20 ml
Position Current sample
Drain Yes
Drain pump DRAIN
Condition No
014 Conditioning
Type Fix
Interval 1
Position Conditioning beaker
Time 30 s
Speed 30 %
Condition No
015 End of sample
METTLER TOLEDO Application M462-2010
Determination of Palladium Content Palladium(II) was determined by potentiometric titration with hexadecylpyridinium chloride (HDPCl) using a surfactant sensitive electrode in combination with a reference electrode.
Preparation and Procedures Hexadecylpyridinium chloride (HDPCl, 0.02 mol/L): - 7.16020 g HDPCl monohydrate is cautiously
dissolved (avoid foam formation) in 200-300 mL deionized water in a 1 L volumetric flask.
- The flask is slowly filled up with deionized water. - Note: HDPCl is also called cetylpyridinium
chloride (CPC). Sodium dodecylsulfate (SDS, 0.004 mol/L): - 1.15352 g is added into a 1 L volumetric flask,
which is slowly filled up with deionized water to avoid the formation of foam.
Palladium chloride, PdCl2 (0.01 mol/L): - 0.18230 g is added in a 100 mL volumetric flask. - The flask is filled with approx. 80 mL mixed
solution (0.5 mol/L NaCl in 0.5 mol/L HCl). - PdCl2 dissolves slowly while stirring. After
complete dissolution, fill up to the mark by adding further mixed solution.
Titer determination of HDPCl: - 10 mL SDS (0.004 mol/L) was added to 50 mL
deionized water and subsequently titrated with HDPCl.
Remarks
Sample preparation: - 5 mL 0.01 mol/L PdCl2 solution is added into a
titration beaker. - 50 mL mixed solution (0.5 mol/L NaCl in 0.5
mol/L HCl) is automatically added by an additional dosing unit.
- Subsequently, 5 mL ethanol is added to ensure complete dissolution of PdCl2, and also to reduce foaming as well as flocculation during titration.
Calculations: For all calculations, the actual concentrations calculated on the basis of the actual sample mass have been used (see preparation and procedures). A recovery of 101.983% for Pd(II) was obtained.
Sample Palladium chloride, PdCl2 c(PdCl2) = 0.01 mol/L
Compound Palladium(II), Pd2+ M = 106.42 g/mol, z = 2
Chemicals - Mixed solution: 0.5 mol/L NaCl in 0.5 mol/L HCl
- Ethanol
Titrant Hexadecylpyridinium chloride HDPCl, c(HDPCl) = 0.02 mol/L
Standard Sodium dodecylsulfate (SDS) c(SDS) = 0.004 mol/L
Indication - DS800 TwoPhase surfactant sensitive sensor
-DX200 Reference half-cell
Chemistry PdCl2 + 2 C21H38NCl → [Pd(II)(C21H38N)2]Cl4
Calculation R1 = VEQ, [mL] R2 = Q*C/m C = 1/z, [mol/L], z = 2
Waste disposal
Pd(II) as aqueous heavy metal waste
Author, Version
Thomas Hitz, MSG Anachem, May 2010
METTLER TOLEDO Page 1 of 4 Titration Application M462-2010
Instruments - T50/T70/T90 Titration Excellence - XS205 Balance - Rondolino sample changer
Accessories - 1 additional dosing unit - 2 x 10 mL DV1010 burette - Titration beaker ME-101974 - LabX pro titration software
Results All results Method-ID m462 Sample PdCl2 (1/5) R1 (Consumption) 5.25996 mL Sample PdCl2 (2/5) R1 (Consumption) 5.23816 mL Sample PdCl2 (3/5) R1 (Consumption) 5.20766 mL Sample PdCl2 (4/5) R1 (Consumption) 5.19172 mL Sample PdCl2 (5/5) R1 (Consumption) 5.18240 mL Sample PdCl2 (1/5) R2 (Content) 0.01058 mol/L Sample PdCl2 (2/5) R2 (Content) 0.01054 mol/L Sample PdCl2 (3/5) R2 (Content) 0.01047 mol/L Sample PdCl2 (4/5) R2 (Content) 0.01044 mol/L Sample PdCl2 (5/5) R2 (Content) 0.01042 mol/L Statistics Method-ID m462 R2 Content Samples 5 Mean 0.01049 mol/L s 0.00007 mol/L srel 0.647%
Titration curve
METTLER TOLEDO Page 2 of 4 Titration Application M462-2010
METTLER TOLEDO Page 3 of 4 Titration Application M462-2010
Table of measured values
Volume Increment Signal Change 1st deriv. Time Temperature mL mL mV mV mV/mL s °C 0 NaN 107.1 NaN NaN 0 25 2.5 2.5 122.7 15.6 NaN 13 25 2.55 0.05 120.1 -2.6 NaN 78 25 2.6 0.05 119.9 -0.2 NaN 84 25 2.65 0.05 119.9 0 NaN 89 25 2.7 0.05 119.9 0 -5.14 94 25 2.75 0.05 119.8 -0.1 2.64 99 25 2.8 0.05 119.8 0 -0.28 104 25 4.9 0.05 127.2 0.5 11.45 317 25 4.95 0.05 127.8 0.6 12.97 322 25 5 0.05 128.5 0.7 13.95 327 25 5.05 0.05 129.3 0.8 15.35 332 25 5.1 0.05 130.2 0.9 20.4 337 25 5.15 0.05 131.2 1 26.92 342 25 5.2 0.05 132.3 1.1 32.86 348 25 5.25 0.05 134.2 1.9 35.55 355 25EQP1 5.259959 NaN 134.7 NaN 35.56 NaN NaN 5.3 0.05 136.8 2.6 34.59 364 25 5.35 0.05 138.2 1.4 29.91 369 25 5.4 0.05 139.3 1.1 22.24 374 25 5.45 0.05 140 0.7 15.16 379 25 5.5 0.05 140.8 0.8 11.23 384 25 5.55 0.05 141.3 0.5 10.66 389 25 5.6 0.05 141.7 0.4 9.77 394 25 5.65 0.05 142.4 0.7 8.68 400 25 5.7 0.05 142.7 0.3 7.76 405 25 5.75 0.05 143.1 0.4 7.02 410 25
Comments
• In this application, the sample is diluted by automatically adding 50 mL NaCl/HCl solution using an additional dosing unit.
• This step can be also performed manually prior titration. In this case, the method function “Dispense” has to be deleted.
METTLER TOLEDO Page 4 of 4 Titration Application M462-2010
Method 001 Title
Type General titration
Compatible with T50 / T70 / T90
Method ID m462
Title Pd analysis
Author hitz
Date/Time 10.05.2010
Modified at 10.05.2010
Modified by hitz
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 PdCl2
Entry type Fixed volume
Volume [mL] 5
Density [g/mL] 1.0
Correction factor 1.0
Temperature [°C] 25.0
003 Titration stand (Rondolino TTL)
Type Rondolino TTL
Titration stand Rondolino TTL 1
004 Dispense (normal) [1]
Titrant HCl/NaCl
Concentration [mol/L] 0.5
Volume [mL] 50
Dosing rate [mL/min] 60.0
Condition No
005 Stir
Speed [%] 30
Duration [s] 30
Condition No
006 Titration (EQP) [1]
Titrant
Titrant HDPCl
Concentration [mol/L] 0.02
Sensor
Type mV
Sensor DS800
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed [%] 30
Predispense
Mode Volume
Volume [mL] 2.5
Wait time [s] 60
Control
Control User
Titrant addition Incremental
dV [mL] 0.05
Mode Equilibrium controlled
dE [mV] 0.5
dt [s] 2.0
t (min)[s] 5
t (max)[s] 30.0
Evaluation and recognition
Procedure Standard
Threshold [mV/mL] 15
Tendency Positive
Ranges 0
Add. EQP criteria Steepest jump
Steepest jumps 1
Termination
At Vmax [mL] 7
At potential No
At slope No
After number of
recognized EQPs No
Combined termination
criteria No
Accompanying stating No
007 Calculation R1
Result Consumption HDPCl
Result unit mL
Formula R1=VEQ
Constant C=1
M M[None]
z z[None]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
008 Calculation R2
Result Content Pd
Result unit mol/L
Formula R2=Q*C/m
Constant C=1/z
M M[Palladium]
z z[Palladium]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
009 Record
Summary No
Results Per sample
Raw results Per sample
Table of meas. values All titration functions
Sample data No
Resource data No
E - V All titration functions
dE/dV - V All titration functions
log dE/dV - V No
d2E/dV2 - V No
BETA – V No
E - t No
V - t No
dV/dt - t No
T – t No
E – V & dE/dV – V No
V – t & dV/dt – t No
Method No
Series data No
Condition No
010 End of sample
METTLER TOLEDO Application M460-2010
Copper Content in Copper Mining Solutions Determination of copper content in intermediate products in copper mining. Copper is determined by iodometric titration with sodium thiosulphate as a titrant. The redox reaction is indicated by a platinum pin sensor with plastic shaft.
Preparation and Procedures CAUTION: Due to the presence of hydrofluoric acid, HF, in the solution, always work in a fume cupboard, wear gloves, safety glasses and a lab coat. • Depending on the expected concentration of
Cu2+ in the sample solution, the amount of sample is chosen in such a way that the final amount of Cu2+ in the titration vessel is ~ 0.5 mmol.
• To the sample solution, excess ammonium hydrogen fluoride (NH4)(HF2) is added for masking of Fe3+ (see ‘Chemistry’). If any Fe3+ is present freely in the solution it will interfere with the Cu2+ determination by reacting with the thiosulphate to form Fe2+.
• Enough excess of potassium iodide, KI, is added to ensure that all the Cu2+ ions present in the solution can react to form I2.
• Subsequently, the generated I2 is then titrated with sodium thiosulphate, Na2S2O3, to determine the copper content via iodometric titration.
Remarks
- Because of the presence of HF in the solution, extreme care has to be taken in handling the samples.
- Neutralize the sample to annihilate the danger from HF Before final disposal.
- In addition to masking of the Fe3+, (NH4)(HF2) also keeps the pH at a low enough value for the redox reaction to complete fully.
- Should no (NH4)(HF2) be added, please make sure to add e.g. HCl to keep the pH low enough.
Note: • The addition of (NH4)(HF2) to the sample
cannot be automated with a dosing unit as the fluoride in acidic environment would corrode the glass of the burette. A peristaltic pump can be used, indeed.
• Addition of the KI solution can be automated with an extra dosing unit, indeed.
Sample Leach solution from copper ore, e.g. Chalcopyrite (CuFeS2 ). 5 mL
Compound Copper, Cu2+, M = 63.55 g/mol, z=1
Chemicals - KI solution, 10% w/w - ammonium hydrogen
fluoride solution, (NH4)(HF2) ~0.3 M solution for excess
(add > 5 mL)
Titrant Sodium thiosulfate, Na2S2O3 c(Na2S2O3) = 0.1 M
Standard Potassium iodate, KIO3
Indication - DM240-SC - DX202 (reference)
Chemistry 2 Cu2+ + 4 I- → 2 CuI + I2 I2 + 2 S2O3
2- → 2 I- + S4O62
Fe3+ + 6 F- → [FeF6]3-
Calculation Content (g/L) R1 = Q*C/m C = M/z Content (mol/L) R2 = Q*C/m C = 1/z
Waste disposal
Neutralised HF solutions do not require special disposal. Copper and iron should be disposed as heavy metals.
Author, Version
Melanie Nijman, MSG Anachem, March 2010
METTLER TOLEDO Page 1 of 4 Titration Application M460-2010
METTLER TOLEDO Page 2 of 4 Titration Application M460-2010
Instruments - T50/T70/T90 Titration Excellence - XS205 Balance - Rondo 20 sample changer
Accessories - 2 x 10 mL DV1010 burettes - Titration beakers ME-101974 - LabX pro titration software
Results
Samples 1/6 Copper solution 5.0 mL 2/6 Copper solution 5.0 mL 3/6 Copper solution 5.0 mL 4/6 Copper solution 5.0 mL 5/6 Copper solution 5.0 mL 6/6 Copper solution 5.0 mL Results Comment / ID Rx Result Unit Name 1/6 Copper solution R1 = 6.3795 g/L Content R2 = 0.10040 mol/L Content 2/6 Copper solution R1 = 6.3862 g/L Content R2 = 0.10051 mol/L Content 3/6 Copper solution R1 = 6.3855 g/L Content R2 = 0.10050 mol/L Content 4/6 Copper solution R1 = 6.4007 g/L Content R2 = 0.10074 mol/L Content 5/6 Copper solution R1 = 6.3808 g/L Content R2 = 0.10042 mol/L Content 6/6 Copper solution R1 = 6.3790 g/L Content R2 = 0.10039 mol/L Content Statistics Rx Name n Mean value Unit s srel [%] R1 Content 6 6.3853 g/L 0.0081 0.128 R2 Content 6 0.10049 mol/L 0.00013 0.130
Titration curve
Table of measured values
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL s 0 NaN 355.9 NaN NaN 0 0.02 0.02 356 0.1 NaN 14 0.04 0.02 355.9 -0.1 NaN 17 0.09 0.05 355.8 -0.1 NaN 20 0.215 0.125 355.5 -0.3 NaN 23 0.415 0.2 354.8 -0.7 -3.16 26 0.615 0.2 354.2 -0.6 -3.54 29 0.815 0.2 353.5 -0.7 -3.65 32 1.015 0.2 352.7 -0.8 -3.83 35 1.215 0.2 351.9 -0.8 -3.92 38 1.415 0.2 351.1 -0.8 -4.01 41 1.615 0.2 350.4 -0.7 -4.17 44 1.815 0.2 349.4 -1 -4.44 47 2.015 0.2 348.6 -0.8 -4.78 50 2.215 0.2 347.6 -1 -5.17 53 2.415 0.2 346.4 -1.2 -5.57 56 2.615 0.2 345.3 -1.1 -5.98 59 2.815 0.2 344.1 -1.2 -6.51 62 3.015 0.2 342.7 -1.4 -7.09 65 3.215 0.2 341.2 -1.5 -7.99 69 3.415 0.2 339.5 -1.7 -8.94 72 3.615 0.2 337.6 -1.9 -10 75 3.815 0.2 335.3 -2.3 -11.05 79 4.015 0.2 332.7 -2.6 -11.92 83 4.215 0.2 329.8 -2.9 -16.13 86 4.415 0.2 325.7 -4.1 -25.43 90 4.615 0.2 320.3 -5.4 -44.09 94 4.815 0.2 311.5 -8.8 -85.99 99 4.9805 0.1655 296.8 -14.7 -154.76 104 5.025 0.0445 289 -7.8 -165.77 107 EQP1 5.045532 NaN 285 NaN -169.75 NaN 5.0485 0.0235 284.4 -4.6 -139.72 110 5.0845 0.036 272.5 -11.9 -163.95 114 5.1045 0.02 268.3 -4.2 -120.18 118 5.1545 0.05 257.6 -10.7 -125.93 121 5.1925 0.038 255.7 -1.9 -99.48 125 5.2875 0.095 255.3 -0.4 NaN 128 5.4875 0.2 256.7 1.4 NaN 131 5.6875 0.2 257.3 0.6 NaN 134 5.8875 0.2 256.3 -1 NaN 137 6.0875 0.2 255.1 -1.2 NaN 140
Comments
• Because of the presence of hydrofluoric acid in the sample to be titrated, no glass redox electrode can be used (e.g. DMi140-SC). Especially for these kinds of applications, the polymer redox half-cell DM240-SC sensor has been developed, which is used in this application (see picture on the right).
• This sensor consists of a platinum wire mounted into a plastic shaft.
• In addition to the DM240-SC half-cell redox sensor, the special polymer reference sensor DX202-SC is used, which is also suitable for use in HF solutions (see e.g. M366).
METTLER TOLEDO Page 3 of 4 Titration Application M460-2010
METTLER TOLEDO Page 4 of 4 Titration Application M460-2010
Method 001 Title
Type General titration
Compatible with T50 / T70 / T90
ID MN409
Title Copper content HF
Author Administrator
Date/Time 18.03.2010 10:20:38
Modified at 19.03.2010 13:31:07
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Copper Solution
Entry type Fixed volume
Volume [mL] 5.0
Density [g/mL] 1.0
Correction factor 1.0
Temperature [°C] 25.0°C
003 Titration stand (Rondo/TowerA)
Type Rondo/Tower A
Titration stand Rondo60/1A
Lid handling No
004 Stir
Speed [%] 30
Duration [s] 10
Condition No
005 Dispense (normal) [1]
Titrant 10% KI
Concentration 1
Volume [mL] 10
Dosing rate [mL/min] 60.0
Condition No
006 Titration (EQP) [1]
Titrant
Titrant Na2S2O3
Concentration [mol/L] 0.1
Sensor
Type mV
Sensor DM240-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed [%] 30
Predispense
Mode None
Wait time [s] 10
Control
Control User
Titrant addition Dynamic
dE (set value) [mV] 8.0
dV (min) [mL] 0.02
dV (max) [mL] 0.2
Mode Equilibrium controlled
dE [mV] 1.0
dt [s] 2
t (min) [s] 3
t (max) [s] 10
Evaluation and recognition
Procedure Standard
Threshold [mV/mL] 80
Tendency None
Ranges 0
Add. EQP criteria No
Termination
At Vmax [mL] 10.0
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating No
Condition No
007 Calculation R1
Result Content
Result unit g/L
Formula R1=Q*C/m
Constant C= M/z
M M[Copper]
z z[Copper]
Decimal places 4
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
008 Calculation R2
Result Content
Result unit mol/L
Formula R2=Q*C/m
Constant C= 1/z
M M[None]
z z[None]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
009 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle[mL] 20
Position Current position
Drain No
Condition No
010 Conditioning
Type Fix
Interval 1
Position Conditioning beaker
Time [s] 10
Speed [%] 30
Condition No
011 End of sample
METTLER TOLEDO Page 1 of 7 Titration Application M459-2010
METTLER TOLEDO Application M459-2010 Automated Determination of Iron Content in Iron Ores
The iron content in iron ores is determined by redox titration in strong acid solution with potassium dichromate K2Cr2O7 as a titrant. The potential change is monitored by a combined platinum ring electrode.
Preparation and Procedures CAUTION: Work in a fume hood, use safety goggles and wear gloves.
Sample dissolution:
- Approximately 0.05 to 0.1 g of iron powder is accurately weighed into a glass titration beaker.
- 40 mL concentrated HCl is added. - The sample is then gently heated (70-90°C) on a
hot plate while stirring until complete iron. Let the sample cool down.
Titration: - Prior to titration with K2Cr2O7, Fe(III) has to be
reduced to Fe(II) by tin chloride, SnCl2, to yield the total iron content.
- The addition of SnCl2 can be automated by means of an endpoint titration function. Initially, the potential needs to be determined where the solution turns colorless when adding SnCl2. In this case, the endpoint was set to 120 mV.
- Add 3 mL of each concentrated phosphoric and sulfuric acid for better endpoint detection. This optimizes the reduction potential and potential interferences by Fe(III) are suppressed by its complexation with PO4
3-. - EQP: The titration by K2Cr2O7 shows two
equivalence points: The first is caused by the excess ofSnCl2 while the second EQP corresponds to the iron content.
Remarks
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- SnCl2 solution (approx. 1 mol/L): 30 g SnCl2 x 2 H2O (M = 225.63) is dissolved 100 mL conc. HCl, and diluted to 200 mL with deionized water.
- Rinse the sensor after each sample. If necessary, clean the metal ring of the redox electrode with a paper tissue at the end of a sample series.
Sample Iron ores, 0.08 - 0.15 g Approx. 60% iron content
Compound Iron, Fe M = 55.85; z = 1
Chemicals Conc. hydrochloric acid, HCl
Conc. sulphuric acid, H2SO4
Conc. phosphoric acid, H3PO4
Deionized water
Titrant Potassium dichromate, K2Cr2O7 c(1/6 K2Cr2O7) = 0.1 mol/L Tin(II) chloride, SnCl2 c(SnCl2) = 1 mol/L
Standard For K2Cr2O7: (NH4)2Fe(SO4)2
Indication Combined redox Pt-sensor e.g. DMi140-SC
Chemistry Reduction to Fe(II): 2 Fe3+ + Sn2+ → 2 Fe2+ + Sn4+ Titration: 6 Fe2+ + Cr2O7
2- + 14 H+ → 6 Fe3+ + 2 Cr3+ + 7 H2O
Calculation Content • R1 = Q*C/m • C = M/(10*z)
Waste disposal
Neutralize the sample with sodium hydroxide before final disposal as special waste (Chromium).
Author, Version
Susanne Wahlen, MSG Anachem, April 2010 Revised May 2010 / C. De Caro Craig Gordon, MSG Anachem, May 2005
METTLER TOLEDO Page 2 of 7 Titration Application M459-2010
Instruments - T70/90 Titration Excellence (T50: Dispensing of SnCl2 solution with “Dispense” function)
- XS205 Balance - Rondo 20 Sample Changer with PowerShower™
Accessories - 2 x 10 mL DV1010 burette - 2 x 5 mL DV1005 burette - 3 x additional Dosing Units (EP/Dispense with SnCl2, dosing of H3PO4 and H2SO4) - Glass titration beaker ME-101446 - LabX titration pro
Results (T70/T90)
METTLER TOLEDO T90
T90 Fumehood
Method: MS1055 Fe(II) in Ore (Rondo) 24.03.2010 14:22:41
Results
Series start time 24.03.2010 14:23:33
No. Comment/ID Start time Rx Result Unit Name
1/8 Iron Ore(Greece) 24.03.2010 14:23:33 R1 = NaN mL EP Consumption
R2 = 2.881 mL 2nd EQP Consumption
R3 = 37.953(2) % Iron Content
2/8 Iron Ore(Greece) 24.03.2010 14:23:33 R1 = 0.450 mL EP Consumption
R2 = 6.904 mL 2nd EQP Consumption
R3 = 38.692 % Iron Content
3/8 Iron Ore(Greece) 24.03.2010 14:51:09 R1 = 0.446 mL EP Consumption
R2 = 6.816 mL 2nd EQP Consumption
R3 = 38.195 % Iron Content
4/8 Iron Ore(Greece) 24.03.2010 15:04:14 R1 = 0.444 mL EP Consumption
R2 = 6.982 mL 2nd EQP Consumption
R3 = 39.126(2) % Iron Content
5/8 Iron Ore(Greece) 24.03.2010 15:16:22 R1 = 0.447 mL EP Consumption
R2 = 6.845 mL 2nd EQP Consumption
R3 = 38.358 % Iron Content
6/8 Iron Ore(Greece) 24.03.2010 15:29:39 R1 = 0.444 mL EP Consumption
R2 = 6.819 mL 2nd EQP Consumption
R3 = 38.216 % Iron Content
7/8 Iron Ore(Greece) 24.03.2010 15:42:50 R1 = 0.438 mL EP Consumption
R2 = 6.859 mL 2nd EQP Consumption
R3 = 38.436 % Iron Content
6/8 Iron Ore(Greece) 24.03.2010 15:55:44 R1 = 0.440 mL EP Consumption
R2 = 6.850 mL 2nd EQP Consumption
R3 = 38.385 % Iron Content
Statistics: n = 6 R3 = 38.380 ± 0.180% s = 0.180% srel = 0.469% (2) Excluded
METTLER TOLEDO Page 3 of 7 Titration Application M459-2010
Titration curve (T70/T90)
Table of measured values (T70/T90)
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL min:s -------------------------------------------------------------------------------------------- 0 NaN 106.2 NaN NaN 0 0.02 0.02 113.3 7.1 NaN 5 0.04 0.02 121.8 8.5 NaN 11 0.06 0.02 128 6.2 NaN 16 0.096 0.036 136.4 8.4 NaN 21 0.141 0.045 145.4 9 193.28 27 0.1885 0.0475 152.6 7.2 167.23 33 0.2565 0.068 166.6 14 154.18 38 0.2855 0.029 168 1.4 156.61 44 0.358 0.0725 182 14 181.11 49 0.378 0.02 184 2 191.62 54 0.428 0.05 194.5 10.5 244.58 61 0.448 0.02 200.4 5.9 278.22 66 0.468 0.02 205.7 5.3 311.9 71 0.5015 0.0335 217.6 11.9 411.88 77 0.5215 0.02 225.9 8.3 495.53 82 0.5415 0.02 236.1 10.2 614.63 87 0.5615 0.02 250 13.9 704.88 94 0.5815 0.02 265.5 15.5 743.42 101 EQP1 0.58904 NaN 272.2 NaN 748.48 NaN 0.6015 0.02 283.3 17.8 742.57 108 0.6215 0.02 295.7 12.4 670.24 113 0.6415 0.02 307.5 11.8 555.57 118 0.6615 0.02 318.3 10.8 450.54 123 0.6815 0.02 327.6 9.3 386.46 129 0.702 0.0205 334.4 6.8 329.82 135 0.7355 0.0335 341.5 7.1 251.25 140 0.7935 0.058 349.8 8.3 170.45 145 0.878 0.0845 358.9 9.1 115.43 150 0.976 0.098 366.3 7.4 84.31 156 1.128 0.152 375.1 8.8 60.62 160 1.3085 0.1805 383.1 8 45.23 166 1.5425 0.234 391.2 8.1 34 171 1.837 0.2945 399.4 8.2 26.29 176 2.137 0.3 406.6 7.2 22 181 2.437 0.3 412.8 6.2 19.6 186
METTLER TOLEDO Page 4 of 7 Titration Application M459-2010
Instruments - DL58 with manual addition of SnCl2 solution - AT261 Balance This method can also be run with the following instruments: - DL55/DL58 (2 DV090 burettes drives) and DL70ES/77 instruments (4 DV090 burette drives) - DL50/DL53, DL67 (manual addition of SnCl2 solution, phosphoric and sulphuric acids).
Accessories - 2 x 10 mL DV1010 burettes - Glass titration beaker ME-101446 - LabX titration pro
Results (DL58)
METTLER TOLEDO DL58 V2.4
DL58 Fumehood
Method: Fe003 Iron in Iron Ore 08-Jun-05 11:46 AM
Results
Series start time 08-Jun-05 4:48 PM
No. Note / ID Start time Rx Result Unit Name
1 Fe2O3 08-Jun-05 4:48 PM R1 = 1.514 mL Consumption
R3 = 12.215 mL Consumption
R4 = 64.334 % Iron Content
2 Fe2O3 08-Jun-05 6:09 PM R1 = 1.452 mL Consumption
R3 = 10.509 mL Consumption
R4 = 63.499 % Iron Content
3 Fe2O3 08-Jun-05 6:36 PM R1 = 1.363 mL Consumption
R3 = 10.300 mL Consumption
R4 = 64.389 % Iron Content
4 Fe2O3 08-Jun-05 7:10 PM R1 = 1.284 mL Consumption
R3 = 11.341 mL Consumption
R4 = 64.917 % Iron Content
Statistics: 64.285 ± 0.586% , srel: 0.912%
Titration curve (DL58)
METTLER TOLEDO Page 5 of 7 Titration Application M459-2010
Table of measured values (DL58)
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL min:s -------------------------------------------------------------------------------------------- ET1 0.0000 103.9 0:06 0.0200 0.0200 118.1 14.2 707.6 0:17 0.0400 0.0200 114.9 -3.2 -158.3 0:47 0.0600 0.0200 118.3 3.4 168.0 1:18 0.1050 0.0450 142.0 23.7 527.0 1:48 0.1250 0.0200 149.0 7.0 352.2 2:17 0.1700 0.0450 204.7 55.7 1237.8 2:30 0.1900 0.0200 221.6 16.9 846.5 2:36 EQP1 0.2100 0.0200 250.6 29.0 1447.5 2:51 0.2300 0.0200 266.9 16.3 817.4 2:59 0.2720 0.0420 290.9 24.0 570.8 3:04 0.2960 0.0240 298.7 7.8 325.8 3:10 0.3440 0.0480 310.9 12.1 253.1 3:15 0.3880 0.0440 317.9 7.0 160.1 3:21 . . . . . . . . . . . . . . . . . . 11.3680 0.0890 541.0 8.8 98.7 7:51 11.4310 0.0630 549.1 8.1 128.2 7:56 11.4810 0.0500 558.3 9.2 184.8 8:02 11.5140 0.0330 566.0 7.7 233.0 8:07 11.5420 0.0280 576.0 10.0 355.4 8:14 11.5620 0.0200 583.5 7.5 374.8 8:19 11.5820 0.0200 599.0 15.5 775.4 8:25 11.6020 0.0200 625.1 26.1 1305.4 8:32 EQP2 11.6220 0.0200 833.9 208.8 10439.2 9:02 11.6420 0.0200 838.0 4.1 206.8 9:14 11.6620 0.0200 839.6 1.6 80.8 9:19 11.6860 0.0240 841.9 2.3 96.9 9:32 11.7340 0.0480 843.4 1.5 31.0 9:39 11.7830 0.0490 843.9 0.5 10.6 9:47 11.8810 0.0980 845.8 1.9 19.1 9:53 12.0770 0.1960 847.9 2.1 10.6 10:00 12.3770 0.3000 850.0 2.1 7.1 10:06 12.6770 0.3000 852.0 2.0 6.7 10:15
Comments and Methods
Chemical reactions:
1. Fe3+ has first to be reduced to Fe2+. This is achieved by adding a concentrated solution of stannous chloride, SnCl2 according to the equation: 2 Fe3+ + Sn2+ → 2 Fe2+ + Sn4+
SnCl2 can be added manually until the solution becomes colorless, or it can be added using an endpoint titration function. The titration is stopped at the potential achieved when the solution becomes colorless.
To determine this value, it is first necessary to measure the potential after manual addition. Afterwards, this value is entered as absolute EP in the titration method.
2. Iron can be now titrated with potassium dichromate, K2Cr2O7. This titration leads to two equivalence points according to the following reactions:
- 1st EQP: Excess SnCl2 arising from the EP titration is oxidized with potassium dichromate.
3 Sn2+ + Cr2O72- + 14 H+ → 3 Sn4+ + 2 Cr3+ + 7 H2O
- 2nd EQP: Oxidation of Fe 2+ with potassium dichromate.
6 Fe2+ + Cr2O72- + 14 H+ → 6 Fe3+ + 2 Cr3+ + 7 H2O
METTLER TOLEDO Page 6 of 7 Titration Application M459-2010
Tx Titrator
Method MS1055 Fe(II) in Ore (Rondo)
Version 24-03-2010 14:45
001 - Title
Type ............................... General titration
Compatible with .................... T70/90
Method ID .......................... MS1055
Title .............................. Fe(II) in Ore (Rondo)
Author ............................. wahlen
Date/time .......................... 24.03.2010 11:53
Modified on ........................ 24.04.2010 14:22
Modified by ........................ wahlen
Protect ............................ No
SOP ................................ None
002 - Sample
Number of IDs ...................... 1
ID1 .............................. Iron Ore
Entry type ......................... Weight
Lower limit [g] .................. 0.08
Upper limit [g] .................. 0.15
Density [g/mL] ................... 1.0
Correction factor ................ 1.0
Temperature [°C] ................. 25
Entry ............................ Arbitrary
003 – Titration stand (Rondo/Tower A)
Type ............................... Rondo/RondoA
Titration stand .................... Rondo60/1A
Lid handling ....................... No
004 – Stir
Speed [%] .......................... 50
Duration [s] ....................... 15
Condition .......................... No
005 – Titration (EP) [1]
Titrant
Titrant .......................... SnCl2
Concentration [mol/L] ............ 1.0
Sensor
Type ............................. mV
Sensor ......................... DMi140-SC
Unit. .......................... mV
006 - Temperature acquisition
Temperature acquisition .......... No
Stir
Speed [%] ........................ 45
Predispense
Mode ............................. None
Wait time [s] .................... s
Control
Mode ............................. Absolute
Tendency ......................... Negative
End point value [mV] ............. 120
Control band [mV] ................ 350
Dosing rate (max) [mL/min] ....... 7
Dosing rate (min) [μL/min] ....... 10
Termination
At EP ............................ Yes
Termination delay [s] ............ 0
At Vmax [mL] ..................... 15.0
Max. time [s] .................... infinity
Accompanying stating
Accompanying stating ............. No
Condition
Condition ........................ No
007 - Calculation R1
Result ............................. EP Consumption
Result Unit ........................ mL
Formula ............................ R1=VEQ
Constant C= ........................ 1
M .................................. M[None]
z .................................. z[None]
Decimal places ..................... 3
Result limits ...................... No
Record statistics .................. Yes
Extra statistical functions ........ No
Send to buffer ..................... No
Condition .......................... No
008 - Stir
Speed [%] .......................... 50
Duration [s] ....................... 2
Condition .......................... No
009 – Dispense (normal) [1]
Titrant ............................ Conc H3PO4
Concentration ...................... 16
Volume [mL] ........................ 3.0
Dosing rate [mL/min] ............... 40
Condition .......................... No
010 – Dispense (normal) [2]
Titrant ............................ Conc H2SO4
Concentration ...................... 18
Volume [mL].........................3.0
Dosing rate [mL/min]................20
Condition...........................No
011 - Stir
Speed [%]...........................50
Time [s]............................15
Condition...........................No
012 – Titration (EQP) [2]
Titrant
Titrant...........................1/6 K2Cr2O7
Concentration [mol/L].............0.1
Sensor..............................DM140
Type..............................mV
Sensor..........................DMi140-SC
Unit............................mV
Temperature acquisition
Temperature acquisition...........No
Stir
Speed [%].........................45
Predispense
Mode..............................None
Wait time [s].....................0
Control
Control...........................User
Titrant addition................Dynamic
dE (set value) [mV] .............8.0
dV (min) [mL] ...................0.02
dV (max) [mL] ...................0.3
Mode..............................Equilibrium controlled
dE [mV] .........................0.5
dt [s]..........................1.0
t(min)[s] .......................5
t(max)[s] .......................30
Evaluation and recognition
Procedure.........................Standard
Threshold [mV/mL].................150
Tendency..........................Positive
Ranges............................1
Lower limit 1 [mV]................150
Upper limit 1 [mV]................2000
Add. EQP criteria.................No
Termination
At Vmax [mL]......................10.0
At potential......................No
At slope..........................No
After number of recognized EQPs...Yes
Number of EQPs..................2
Combined termination criteria.....Yes
Accompanying stating
Accompanying stating..............No
Condition
Condition.........................No
013 – Calculation R2
Result..............................2nd EQP Consumption
Result Unit.........................mL
Formula.............................R2=VEQ2[2]
Constant C=.........................1
M...................................M[None]
z...................................z[None]
Decimal places......................3
Result limits.......................No
Record statistics...................Yes
Extra statistical functions.........No
Send to buffer......................No
Condition...........................No
014 – Calculation R3
Result..............................Iron Content
Result Unit.........................%
Formula.............................R3=Q2[2]*C/m
Constant C=.........................M/10*z)
M...................................M[Iron]
z...................................z[Iron]
Decimal places......................3
Result limits.......................No
Record statistics...................Yes
Extra statistical functions.........No
Send to buffer......................No
Condition...........................No
015 - Rinse
Auxiliary reagent...................Water Tower A
Rinse cycles........................1
Vol. per cycle [mL].................10
Position............................Current position
Drain...............................No
Condition...........................No
016- End of sample
Note: The method can be easily used with a T50 titrator:
- Delete either calculation R1 or calculation R2
- Use a “Dispense” function instead of an EP titration
METTLER TOLEDO Page 7 of 7 Titration Application M459-2010
DL5x Titrator
Method Fe003 Iron in Iron ore
Version 08-Jun-2005 11:46
Title
Method ID .......................... Fe003
Title .............................. Iron in Iron ore
Date/time .......................... 08-Jun-2005 11:46
Sample
Sample ID .......................... Fe2O3
Entry type ......................... Weight
Lower limit [g] ................ 0.08
Upper limit [g] ................ 0.15
Molar mass M ....................... 55.85
Equivalent number z ................ 1
Titration stand .................... Stand 1
Temperature sensor ................. Manual
Stir
Speed [%] .......................... 50
Time [s] ........................... 15
EP titration
Titrant/Sensor
Titrant ........................ SnCl2
Concentration [mol/L] .......... 1.0
Sensor ......................... DM140
Unit of meas. .................. mV
Predispensing ...................... No
Titrant addition ................... Dynamic
dE(set) ........................ 8.0
dV(min) [mL] ................... 0.02
dV(max) [mL] ................... 0.15
dE [mV] ........................ 1.0
dt [s] ......................... 1.0
t(min) [s] ..................... 2.0
t(max) [s] ..................... 20.0
Endpoint
Potential[mV,pH,…] ............. 120
Tendency
Tendency ....................... Negative
Termination
Maximum volume [mL] ............ 5.0
Delay[s] ....................... 10
Calculation
Formula ........................... R=VEQ
Constant ...........................
Decimal places ..................... 3
Result unit ........................ mL
Result name ........................ Consumption
Statistics ........................ No
Calculation
Formula ...........................
Constant ...........................
Decimal places ..................... 0
Result unit ........................
Result name ........................ No
Statistics ........................ Yes
Report
Output unit ....................... Computer
Results ............................ No
All results ........................ No
Raw results ........................ No
Table of measured values ........... No
Sample data ........................ No
E - V curve ........................ No
dE/dV – V curve .................... No
d2E/dV2 – V curve ................... No
log dE/dV – V curve... ............. No
E – t curve ........................ No
V – t curve ........................ No
dV/dt - t curve ................... No
Instruction
Text ............................... Add 3mL of conc.
............................... phosphoric
Text ............................... acid followed by 3mL of
Text ............................... conc sulphuric acid!!!
Stir
Speed [%] .......................... 50
Time [s] ........................... 15
EQP titration
Titrant/Sensor
Titrant ........................ 1/6 K2Cr2O7
Concentration [mol/L] .......... 0.1
Sensor ......................... DM140
Unit of meas. .................. mV
Predispensing ...................... to volume
Volume [mL] .................... 0.2
Wait time [s] .................. 20
Titrant addition ................... Dynamic
dE(set) ........................ 8.0
dV(min) [mL] ................... 0.02
dV(max) [mL] ....................0.3
Measure mode........................Equilibrium controlled
dE [mV] .........................0.5
dt [s] ..........................1.0
t(min) [s] ......................5.0
t(max) [s] ......................30.0
Recognition
Threshold .......................400.0
Steepest jump only ..............No
Range ...........................Yes
Limit A [mV, pH,…] ...........200
Limit B [mV, pH,…] ...........2000
Tendency ........................Positive
Termination
at maximum volume [mL] ..........30.0
at potential ....................No
at slope ........................Yes
Slope [mV, pH, …/mL] .......10.0
after number EQPs ...............Yes
n = .......................2
comb. termination criteria ......Yes
Evaluation
Procedure .......................Standard
Potential 1 ....................No
Potential 2 ....................No
Stop for reevaluation ..........No
Calculation
Formula ............................R3=VEQ2[2]
Constant............................C3=1
Decimal places......................3
Result unit.........................mL
Result name.........................Consumption
Statistics .........................No
Calculation
Formula ............................R4=Q2[2]*C4/m
Constant............................C4=M/(10*z)
Decimal places......................3
Result unit.........................%
Result name.........................Iron content
Statistics .........................Yes
Report
Output unit ........................Computer
Results.............................No
All results.........................No
Raw results.........................No
Table of measured values............No
Sample data.........................No
E - V curve.........................No
dE/dV – V curve.....................No
d2E/dV2 – V curve....................No
log dE/dV – V curve.................No
E – t curve.........................No
V – t curve.........................No
dV/dt - t curve ....................No
METTLER TOLEDO Application M622-2010 Determination of Total Iron Content of Iron Ores
The iron content in 60-65% iron ores is titrated with potassium dichromate K2Cr2O7 in strong acid solution after reduction with tin(II) and titanium(III). The potential change is monitored by a combined platinum ring redox sensor.
Preparation and Procedures CAUTION: Work in a fume hood, use safety goggles and wear gloves.
Sample dissolution: - 0.15-0.25 g iron ore is placed in a glass titration
beaker for dissolution. - Place sample beaker in a fume hood. - Add 1 m 10% SnCl2 with a pipette. - Add 20 mL concentrated HCl and swirl the beaker
after addition to ensure complete mixing. - Place beaker on a hot plate set at 125-150°C with
integrated magnetic stirrer. Cover it with a clean watch glass and start digestion of the ore.
- After 10-20 min, swirl beaker to break up any agglomerated particles.
- Digest for a minimum of 40 min in total. - After ore digestion, slightly tilt the beaker and add a
magnetic stirrer bar. Place beaker onto the hot plate. Set temperature to heat sample but avoid boiling. Switch stirrer on, ensuring not to loose any sample.
- While gently stirring, add dropwise 10% SnCl2 solution until the color turns into a pale straw yellow. If too much SnCl2 is added, i.e. if the solution becomes colorless, add dropwise KMnO4 solution to restore the pale yellow color.
- From now on, the sample has to be titrated within 30 min at latest.
- Add dropwise 1% TiCl3 solution until liquid turns colorless. Then add three additional drops.
- Add 5 mL 0.1 M perchloric acid (HClO4). - Wait during 5 s (heating, not boiling), then remove
from hot plate. - Add 40 mL deionized water, rinsing the inside wall of
the beaker. - The sample is ready for titration.
Titration: - Add the prepared titration beakers on the sample
changer rack. - Start titration with potassium dichromate.
Remarks
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- Rinse the electrode after each sample. If necessary, clean the metal ring of the electrode with a paper tissue at the end of a sample series.
Sample Iron ores, 0.15 - 0.25 g 60-65% iron content
Compound Iron, Fe M = 55.85; z = 1
Chemicals 30-34% Hydrochloric acid, HCl
10% Stannous chloride sol., SnCl2
0.4% Potassium permanganate, KMnO4
1% Titanium trichloride, TiCl3
0.1 mol/L Perchloric acid, HClO4
Deionized water
Titrant Potassium dichromate, K2Cr2O7 c(1/6 K2Cr2O7) = 0.1 mol/L
Standard Ammonium ferrous sulfate, (NH4)2Fe(SO4)2
Indication Combined redox Pt-electrode e.g. DMi140-SC
Chemistry Reduction to Fe(II): 2 Fe3+ + Sn2+ → 2 Fe2+ + Sn4+ Titration: 2 Fe2+ + Cr2O7
2- + 14 H+ → 2 Fe3+ + 2 Cr3+ + 7 H2O
Calculation Content • R1 = Q*C/m • C = M/(10*z)
Waste disposal
Neutralize the sample with sodium hydroxide before final disposal as special waste (Chromium).
Author, Version
Li Pei, MT-China, April 1999 Revised March 2010 / C. De Caro
METTLER TOLEDO Page 1 of 4 Titration Application M622-2010
Instruments - DL58 Titrator - AG245 Balance This method can also be run with the G20 and T50/70/90 Titration Excellence (minor
adaptations in their method), and with the DL50/DL53/DL55, and DL67/70ES/77 titrators.
Accessories - 1 x 10 mL DV1010 burette - Glass titration beaker ME-101446 - Sample Changer with pump (e.g. Rondo20) - Printer (EPSON SC 600)
Results METTLER TOLEDO DL58 Titrator V2.0 MTCS ANA MS Application Lab Method 10150 Iron in iron ores 12-Apr-1999 16:57 Measured 13-Apr-1999 11:46 User Li Pei ALL RESULTS No. ID Sample size and results 1 Iron 0.0995 g R1 = 64.7050 % iron content 2 Iron 0.1063 g R1 = 64.7105 % iron content 3 Iron 0.1004 g R1 = 64.8998 % iron content STATISTICS Number results R1 n = 3 Mean value x = 64.7718 % iron content Standard deviation s = 0.11093 % iron content Rel. standard deviation srel = 0.171 %
Titration curve
METTLER TOLEDO Page 2 of 4 Titration Application M622-2010
METTLER TOLEDO Page 3 of 4 Titration Application M622-2010
Table of measured values
Not available
Comments and Methods
1. This method is based on a national standard pretreatment method for the determination of total iron content in iron ores (China, GB 6730.5-86, “The chemistry analysis process for the iron ore and the capacity process for measuring the amount of the whole iron with titanium trichloride and potassium dichromate”, see also ISO 2597-1:2006, ISO 2597-2:2008, and ISO 9507:1990).
2. Samples must be analyszed within 30 min after the 2nd addition of 10% stannous chloride SnCl2 solution.
3. A sample changer is used in this method for a fully automated procedure. The method can be easily modified for manual operation: enter “Stand 1” as titration stand in the function Sample (DL5x, DL7x) or “Manual Stand” (Titration Excellence).
4. After each sample, the sensor is rinsed with deionized water by means of a peristaltic pump connected to the sample changer.
Chemical reactions:
1. During dissolution, iron is oxidized to Fe3+. In order to be titrated with potassium dichromate, Fe3+ has to be reduced to Fe2+. This is achieved by adding a concentrated solution of stannous chloride, SnCl2 according to the equation: 2 Fe3+ + Sn2+ → 2 Fe2+ + Sn4+
Excess SnCl2 is oxidized with potassium permanganate, KMnO4, according to:
5 Sn2+ + 2 MnO4- + 16 H+ → 5 Sn4+ + 2 Mn2+ + 8 H2O
In the sample all iron is present as Fe2+. However, if the prepared sample solution is exposed too long a time to air, Fe2+ is easily oxidized by oxygen to Fe3+. To avoid it, some titanium trichloride, TiCl3, is added in slight excess:
Ti3+ + Fe3+→ Fe2+ + Ti4+
Perchloric acid, HClO4, is added to neutralize excess TiCl3 .
2. Iron can be now titrated with potassium dichromate, K2Cr2O7, according to the following reaction:
6 Fe2+ + Cr2O72- + 14 H+ → 6 Fe3+ + 2 Cr3+ + 7 H2O
Literature:
1. ISO 2597-1:2006, “Iron ores -- Determination of total iron content -- Part 1: Titrimetric method after tin(II) chloride reduction”.
2. ISO 2597-2:2006, “Determination of total iron content -- Part 2: Titrimetric methods after titanium(III) chloride reduction”.
3. ISO 9507:1990, “Determination of total iron content -- Titanium(III) chloride reduction methods”
4. S. Kallmann, E. Kormanova, “Pollution-free method for the determination of iron in iron ore”, Talanta, Vol. 29(8), 1982, pp. 700-702.
5. J. Henry, R. Gelbach, “Dichromate determination of iron using silver reductor”, Ind. Eng. Chem. Anal. Ed., Vol. 16 (1), 1944, p. 49.
METTLER TOLEDO Page 4 of 4 Titration Application M622-2010
DL5x Titrator
Method 10150 Iron in iron ores
Version 12-Apr-1999 16:57
Title
Method ID .......................... 10150
Title .............................. Iron in iron ores
Date/time .......................... 12-Apr-1999 16:57
Sample
Sample ID .......................... Iron
Entry type ......................... Weight
Lower limit [g] ................ 0.05
Upper limit [g] ................ 0.15
Molar mass M ....................... 55.85
Equivalent number z ................ 1
Titration stand .................... ST20A 1
Pump ........................... No
Pump ........................... No
Rinse .......................... Yes
Solvent...................... H2O
Volume [mL].................. 15.0
Conditioning ................... No
Temperature sensor ................. Manual
Stir
Speed [%] .......................... 50
Time [s] ........................... 15
EQP titration
Titrant/Sensor
Titrant ........................ 1/6 K2Cr2O7
Concentration [mol/L] .......... 0.1
Sensor ......................... DM140
Unit of meas. .................. mV
Predispensing ...................... to volume
Volume [mL] .................... 3.0
Wait time [s] .................. 10
Titrant addition ................... Dynamic
dE(set) ........................ 4.0
dV(min) [mL] ................... 0.02
dV(max) [mL] ................... 0.15
Measure mode ....................... Equilibrium controlled
dE [mV] ........................ 1.0
dt [s] ......................... 1.0
t(min) [s] ..................... 6.0
t(max) [s] ..................... 25.0
Recognition
Threshold ...................... 200.0
Steepest jump only ............. No
Range .......................... No
Tendency ....................... Positive
Termination
at maximum volume [mL] ......... 20.0
at potential ................... No
at slope ....................... No
after number EQPs .............. Yes
n = ...................... 1
comb. termination criteria ..... No
Evaluation
Procedure ...................... Standard
Potential 1 ................... No
Potential 2 ................... No
Stop for reevaluation ......... No
Calculation
Formula ........................... R1=Q*C1/m
Constant ........................... C1=M/(10*z)
Decimal places ..................... 4
Result unit ........................ %
Result name ........................ iron content
Statistics ........................ Yes
Calculation
Formula ...........................
Constant ...........................
Decimal places ..................... 0
Result unit ........................
Result name ........................
Statistics ........................ No
Report
Output unit ....................... Printer
Results ............................ Yes
All results ........................ Yes
Raw results ........................ No
Table of measured values ........... Yes
Sample data ........................ No
E - V curve ........................ Yes
dE/dV – V curve .................... Yes
d2E/dV2 – V curve ................... No
log dE/dV – V curve... ............. No
E – t curve ........................ No
V – t curve ........................ No
dV/dt - t curve ................... No
Titration Excellence
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 10150
Title Iron in iron ores
Author METTLER TOLEDO
Date/Time 01.03.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Iron
Entry type Weight
Lower limit 0.05 g
Upper limit 0.15 g
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Stir
Speed 35%
Duration 15 s
005 Titration (EQP) [1]
Titrant
Titrant 1/6 K2Cr2O7
Concentration 0.1 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 3.0 mL
Wait time 10 s
Control
Control User
Titrant addition Dynamic
dE(set) 4.0
dV(min) 0.02 mL
dV(max) 0.15 mL
Meas. val. acquisition Equilibrium controlled
dE 1.0 mV
dt 1.0 s
t(min) 6.0 s
t(max) 25.0 s
Evaluation and recognition
Procedure Standard
Threshold 200 mV/mL
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 20.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EQPs 1
Combined termination
criteria No
006 Calculation R1
Result iron content
Result unit %
Formula R=Q*C/m
Constant C=M/(10*z)
M M[Iron]
z z[Iron]
Decimal places 4
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
007 Record
Summary Yes
Results Per sample
Raw results Per sample
Table of meas. Values Per sample
. . .
008 End of sample
METTLER TOLEDO Page 1 of 10 Titration Application M060-2010
METTLER TOLEDO Application M060-2010 Determination of Iron (Fe(II) ) and Sulphuric Acid (H2SO4)
Potentiometric determination of iron(II) by redox titration with potassium dichromate, K2Cr2O7, and of sulphuric acid by back titration of excess sodium hydroxide with hydrochloric acid. The potential is monitored by a combined platinum ring electrode (Fe), and a combined pH glass electrode (H2SO4).
Preparation and Procedures CAUTION: Use safety goggles and wear gloves.
Sample preparation: - 3-4 g FeSO4*7H2O (M = 278.02) is dissolved in a
500 mL volumetric flask with 150-200 mL 5% sulfuric acid solution.
- Shake the flask to dissolve iron sulfate, and fill up to the mark with 5% H2SO4 solution.
- Pipette 5 mL into a titration beaker.
Titration: Four methods are used to determine Fe(II)/H2SO4. The method sequence is the following:
1) 060 2) 060C 3) 060A 4) 060B
- Method 060 (Fe-determination): Fe(II)-Titration with K2Cr2O7. The pH value has to be between 2 and 3 to avoid oxidation of Fe(II). The result is multiplied by 2 (see “Chemistry”) and stored as auxil. value H2 to be used in method 060B.
- Method 060C (Back value determination): The exact amount of NaOH added to the sample is determined by titration with HCl. This value is stored as auxiliary value H3, and is used in method 060B.
- Method 060A (Sample preparation): Addition of 10 mL 0.1 mol/L NaOH to the Fe(II)-solution. H2SO4 and Fe(II) reacts with NaOH (see “Chemistry”). Since the reaction between Fe and OH- ions is slow, a -conditioning time of 1200 s has been defined in the method.
- Method 060B (Acid determination): A direct titration of H2SO4 is not possible since Fe(II) also reacts with NaOH. After addition of a known amount of NaOH, excess NaOH in the previously prepared samples (060A) is determined by back-titration with HCl. The difference between the sum (Fe + H2SO4) and Fe(II)-content (060) gives the H2SO4 content.
Remarks
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- The electrode is rinsed after each sample with water.
Sample Fe(II)/H2SO4 aqueous solution, 5 mL c(H2SO4) = approx. 5% c(Fe) = approx. 6-7 g/L Fe(SO4)*7H2O
Compound Iron, Fe M = 55.85; z = 1 Sulfuric acid, H2SO4 M = 98.08; z = 2
Chemicals 5% sulfuric acid, H2SO4
Deionized water
Titrant Potassium dichromate, K2Cr2O7 c(1/6 K2Cr2O7) = 0.1 mol/L Hydrochloric acid, HCl, 0.1 mol/L Sodium hydroxide, NaOH, 0.1 mol/L
Standard For K2Cr2O7: (NH4)2Fe(SO4)2
For HCl: THAM (TRIS)
Indication Redox Pt-electrode, DMi140-SC
pH glass electrode, DGi111-SC
Chemistry Titration Fe(II): 2 Fe2+ + Cr2O7
2- + 14 H+ → 2 Fe3+ + 2 Cr3+ + 7 H2O
Reaction with NaOH: Fe2+ + 2 NaOH → Fe(OH)2 + 2 Na+ H2SO4 +2 NaOH→Na2SO4 + H2O
Titration excess NaOH: HCl + NaOH → NaCl + H2O
Calculation 060 : Content Fe(II), g/L • R = Q*C/m, C = M/z
060B: Content H2SO4 g/L • R = Q*C/m, C = M/z For DL7x : replace m with U (volume)
Waste disposal
Neutralize the sample before final disposal as special waste (Chromium).
Author, Version
Maria-José Schmid, MSG, Oct 1991 Revised March 2010 / C. De Caro
METTLER TOLEDO Page 2 of 10 Titration Application M060-2010
Instruments - DL70 Titrator - AT250 Balance This method can also be run with the T50/70/90 Titration Excellence, with the DL70ES/77
titrators, and with the DL5x and DL67 instruments (manual exchange of burettes).
Accessories - 3 x 10 mL DV1010 burette - 2 x additional DV090 burette drive - Sample Changer, i.e. Rondo 20 with pump - Titration beaker ME-101974
Results (Back-value, Fe-determination) 060C Back value measured Oct/18/1991 12:56 Oct/18/1991 12:30 Titrator P100 SW Version 2.0 User mjs RESULTS No Identification Volume Results 1/1 NaOH 12.0 mL 1.031 mmol Back value 1/2 NaOH 10.0 mL 1.030 mol/L mol/L 1/3 NaOH 10.0 mL 1.030 mol/L mol/L STATISTICS Number results R1 n = 3 Mean value x = 1.030 mmol Back value Standard deviation s = 0.0001 mmol Back value Rel. standard deviation srel = 0.006 % Outlier test: no outliers! AUXILIARY VALUE New value H3 = 1.030455 Back value NaOH ============================================================================================================= 060 Fe(II) determination measured Oct/01/1991 14:43 Oct/01/1991 11:53 Titrator P100 SW Version 2.0 User mjs RESULTS No Identification Volume Results 1/1 Fe+H2SO4 10.0 mL 0.0467 mol/L Fe(II) mol/L 6.487 g/L Fe(II) g/L 1/2 Fe+H2SO4 10.0 mL 0.0468 mol/L Fe(II) mol/L 6.504 g/L Fe(II) g/L 1/3 Fe+H2SO4 10.0 mL 0.0468 mol/L Fe(II) mol/L 6.508 g/L Fe(II) g/L 1/4 Fe+H2SO4 10.0 mL 0.0468 mol/L Fe(II) mol/L 6.511 g/L Fe(II) g/L 1/5 Fe+H2SO4 10.0 mL 0.0468 mol/L Fe(II) mol/L 6.501 g/L Fe(II) g/L 1/6 Fe+H2SO4 10.0 mL 0.0469 mol/L Fe(II) mol/L 6.517 g/L Fe(II) g/L 1/7 Fe+H2SO4 10.0 mL 0.0466 mol/L Fe(II) mol/L 6.483 g/L Fe(II) g/L STATISTICS Number results R1 n = 7 Mean value x = 0.0468 mol/L Fe(II) mol/L Standard deviation s = 0.00009 mol/L Fe(II) mol/L Rel. standard deviation srel = 0.193 % Outlier test: no outliers! STATISTICS Number results R2 n = 7 Mean value x = 6.502 g/L Fe(II) g/L Standard deviation s = 0.0126 g/L Fe(II) g/L Rel. standard deviation srel = 0.193 % Outlier test: no outliers!
AUXILIARY VALUE
New value H2 = 0.04677 Fe
Titration curve (Fe-determination)
Sample 1/7
Table of measured values (Fe-determination)
Sample 1/7
METTLER TOLEDO Page 3 of 10 Titration Application M060-2010
METTLER TOLEDO Page 4 of 10 Titration Application M060-2010
Comments
1. Both ferrous ion (Fe2+) and sulfuric acid (H2SO4) react with sodium hydroxide to Fe(OH)2, a solid precipitate, and to water and sodium sulfate. Thus, a direct titration of sulfuric acid is not possible when iron ions (Fe2+ and Fe3+ are present in the sample solution.
2. In addition, the reaction between ferrous ions, Fe2+, and hydroxide ions, OH-, is quite slow. Therefore, a direct titration of Fe2+ with sodium hydroxide is not suitable for titration analysis. For this reason, a back titration with a long waiting time after dispensing excess sodium hydroxide is the method of choice.
3. First, the back value of 10 mL 0.1 M sodium hydroxide is determined with hydrochloric acid (Method 060C). The result is stored as auxiliary value H3. Note that the pH glass electrode has to be adjusted using pH buffer solutions.
4. Subsequently, iron is selectively determined in the sample solution by redox titration with potassium dichromate as a titrant, K2Cr2O7 (Method 060). The result is multiplied by two (equivalence no. z = 2 for this reaction), it is expressed as FeSO4*7H2O, and stored as auxiliary value H2. 6 Fe2+ + Cr2O7
2- + 14 H+ → 6 Fe3+ + 2 Cr3+ + 7 H2O
The pH value of the sample solution (5 mL + 50 mL deionized water) has to be between 2 and 3.
5. Method 060A allows for sample preparation: 10 mL 0.1 M NaOH is added to the sample (5 mL) and a waiting time of 1200 s is defined to achieve complete reaction with iron ions.
6. Subsequently, this sample is analyzed by back-titration of excess NaOH with hydrochloric acid (Method 060B) to get the sulfuric acid content.
Results (H2SO4-determination)
060B Acid determination measured Oct/22/1991 12:11 Oct/22/1991 10:35 Titrator P100 SW Version 2.0 User mjs RESULTS No Identification Volume Results 1/1 Fe+H2SO4 5.0 mL 0.0969 mol/L Total sum 2.4563 g/L Acid content 1/2 Fe+H2SO4 5.0 mL 0.0970 mol/L Total sum 2.4588 g/L Acid content 1/3 Fe+H2SO4 5.0 mL 0.0974 mol/L Total sum 2.4817 g/L Acid content 1/4 Fe+H2SO4 5.0 mL 0.0971 mol/L Total sum 2.4654 g/L Acid content 1/5 Fe+H2SO4 5.0 mL 0.0979 mol/L Total sum 2.5059 g/L Acid content 1/6 Fe+H2SO4 5.0 mL 0.0973 mol/L Total sum 2.4767 g/L Acid content 1/7 Fe+H2SO4 5.0 mL 0.0973 mol/L Total sum 2.4753 g/L Acid content STATISTICS Number results R2 n = 7 Mean value x = 2.4743 g/L Acid content Standard deviation s = 0.01684 g/L Acid content Rel. standard deviation srel = 0.681 % Outlier test: no outliers!
Titration curve (H2SO4-determination)
Sample 1/7
Table of measured values (H2SO4-determination)
Sample 1/7
METTLER TOLEDO Page 5 of 10 Titration Application M060-2010
METTLER TOLEDO Page 6 of 10 Titration Application M060-2010
DL70 Titrator
Method 060C Back value
Version 18-Oct-1991 12:30
Title
Method ID .......................... 060C
Title .............................. Back value
Date/time .......................... 18-Oct-1991 12:30
Sample
Number samples ..................... 3
Titration stand .................... ST20
Entry type ......................... Fixed volume U
Volume [mL] .................... 10.0
ID ................................. NaOH
Molar mass M ....................... 40.0
Equivalent number z ................ 1
Dispense
Titrant ........................... NaOH
Concentration [mol/L] .............. 0.1
Volume [mL] ........................ 10.0
Stir
Speed [%] .......................... 50
Time [s] ........................... 10
Titration
Titrant ............................ HCl
Concentration [mol/L] .............. 0.1
Sensor ............................. DG111-SC
Unit of meas. ...................... as installed
Titration mode ..................... EQP
Predispensing 1 ................ mL
Volume [mL].................. 5.0
Predispensing 2 ................ To potential
Potential [mV,pH, …]......... 10.0
Titrant addition ............... DYN
dE(set)[mV].................. 8.0
Limits dV.................... Absolute
dV(min) [mL] .............. 0.02
dV(max) [mL] .............. 0.2
Measure mode ................... EQU
dE [mV]...................... 1.0
dt [s]....................... 1.0
t(min) [s]................... 2.0
t(max) [s]................... 20.0
Threshold ...................... 10.0
Maximum volume [mL] ............ 15.0
Termination after n EQPs ....... Yes
n = ......................... 1
Evaluation procedure ........... Standard
Rinse
Auxiliary reagent .................. H2O
Volume [mL] ........................ 10.0
Calculation
Result name ....................... Back value
Formula ............................ R=Q
Constant ...........................
Result unit ........................ mmol
Decimal places ..................... 3
Statistics
Ri (i=index) ....................... R1
Standard deviation s ............... Yes
Rel. standard deviation srel ....... Yes
Auxiliary value
ID text ............................ Back value NaOH
Formula ............................ H3=x
Record
Output unit ....................... Printer
Results last sample ................ Yes
All results ........................ No
Conditioning
Interval ........................... 1
Time [s] ........................... 10
Method 060 Fe(II) determination
Version 01-Oct-1991 11:53
Title
Method ID...........................060
Title...............................Fe(II) determination
Date/time...........................01-Oct-1991 11:53
Sample
Number samples......................3
Titration stand.....................ST20
Entry type..........................Fixed volume U
Volume [mL] .....................10.0
ID..................................Fe+H2SO4
Molar mass M........................278.02
Equivalent number z.................1
Stir
Speed [%]...........................50
Time [s]............................10
Titration
Titrant.............................1/6 K2Cr2O7
Concentration [mol/L]...............0.1
Sensor..............................DM140-SC
Unit of meas........................mV
Titration mode......................EQP
Predispensing 1 .................mL
Volume [mL] ..................0.5
Titrant addition ................DYN
dE(set)[mV] ..................8.0
Limits dV ....................Relative
dV(min) [%dosVol] ..........0.5
dV(max) [%buVol] ...........5.0
Measure mode ....................EQU
dE [mV] ......................0.5
dt [s] .......................1.0
t(min) [s] ...................2.0
t(max) [s] ...................20.0
Threshold .......................200.0
EQP range .......................Yes
Limit A [mV,pH,…] ............550.0
Limit B [mV,pH,…] ............900.0
Maximum volume [mL] .............10.0
Termination at potential ........Yes
Potential [mV, pH, …] ........706.22
Termination after n EQPs ........Yes
n = .........................1
Evaluation procedure ............Standard
Steepest jump only ..............Yes
Calculation
Result name ........................Fe(II) mol/L
Formula.............................R=2*(Q*C/U)
Constant............................C=1
Result unit.........................mol/L
Decimal places......................4
Calculation
Result name ........................Fe(II) g/L
Formula.............................R2=Q*C2/U
Constant............................C2=M/z
Result unit.........................mol/L
Decimal places......................4
Rinse
Auxiliary reagent...................H2O
Volume [mL].........................10.0
Record
Output unit ........................Printer
Sample data.........................Yes
Raw results last sample.............Yes
Results last sample.................Yes
Statistics
Ri (i=index)........................R1
Standard deviation s................Yes
Rel. standard deviation srel........Yes
Outlier test........................Yes
Statistics
Ri (i=index)........................R2
Standard deviation s................Yes
Rel. standard deviation srel........Yes
Outlier test........................Yes
Auxiliary value
ID text.............................Fe
Formula.............................H2=x[1]
Record
Output unit ........................Printer
Sample data.........................Yes
Raw results last sample.............Yes
Results last sample.................Yes
Table of measured values............Yes
E – V curve.........................Yes
dE/dV – V curve.....................Yes
METTLER TOLEDO Page 7 of 10 Titration Application M060-2010
Method 060A Sample preparation
Version 22-Oct-1991 10:30
Title
Method ID .......................... 060A
Title .............................. Sample preparation
Date/time .......................... 22-Oct-1991 10:30
Sample
Number samples ..................... 7
Titration stand .................... ST20
Entry type ......................... Fixed volume U
Volume [mL] .................... 5.0
ID ................................. Fe+H2SO4+NaOH
Molar mass M ....................... 0.0
Equivalent number z ................ 1
Dispense
Titrant ........................... Sample
Concentration [mol/L] .............. 0.1
Volume [mL] ........................ 5.0
Dispense
Titrant ........................... NaOH
Concentration [mol/L] .............. 0.1
Volume [mL] ........................ 10.0
Stir
Speed [%] .......................... 60
Time [s] ........................... 60
Measure
Sensor ............................. DG111-SC
Unit of meas. ...................... as installed
dE [mV] ............................ 0.5
dt [s] ............................. 1.0
t(min) mode ........................ Fix
t(min) [s] ..................... 3.0
t(max) [s] ......................... 30.0
Calculation
Result name ....................... pH value
Formula ............................ R=E
Constant ...........................
Result unit ........................
Decimal places ..................... 1
Rinse
Auxiliary reagent .................. H2O
Volume [mL] ........................ 20.0
Conditioning
Interval ........................... 1
Time [s] ........................... 10
Statistics
Ri (i=index) ....................... R1
Standard deviation s ............... Yes
Rel. standard deviation srel ....... Yes
Conditioning
Interval ........................... 1
Time [s] ........................... 1200
Note:
After dispensing of NaOH solution the sample is left onto
the sample changer to allow for reaction during 1200 s.
The electrode is not left into the high alkaline solution to
avoid deterioration of the pH glass membrane with time.
Method 060B Acid determination
Version 22-Oct-1991 10:35
Title
Method ID...........................060B
Title...............................Acid determination
Date/time...........................22-Oct-1991 10:35
Sample
Number samples......................7
Titration stand.....................ST20
Entry type..........................Fixed volume U
Volume [mL] .....................5.0
ID..................................Fe+H2SO4
Molar mass M........................98.0
Equivalent number z.................2
Stir
Speed [%]...........................60
Time [s]............................10
Titration
Titrant.............................H2SO4
Concentration [mol/L]...............0.1
Sensor..............................DM111-SC
Unit of meas........................As installed
Titration mode......................EQP
Predispensing 1 .................mL
Volume [mL] ..................1.0
Titrant addition ................DYN
dE(set)[mV] ..................8.0
Limits dV ....................Absolute
dV(min) [mL] ...............0.02
dV(max) [mL] ...............0.2
Measure mode ....................EQU
dE [mV] ......................0.5
dt [s] .......................1.0
t(min) [s] ...................3.0
t(max) [s] ...................30.0
Threshold .......................3.0
Maximum volume [mL] .............10.0
Termination after n EQPs ........Yes
n = .........................1
Evaluation procedure ............Standard
Calculation
Result name ........................Total sum
Formula.............................R=(H3-Q)*C/U
Constant............................C=1
Result unit.........................mol/L
Decimal places......................4
Calculation
Result name ........................Acid content
Formula.............................R2=(R-H2)*C2
Constant............................C2=M/z
Result unit.........................g/L
Decimal places......................4
Rinse
Auxiliary reagent...................H2O
Volume [mL].........................10.0
Conditioning
Interval............................1
Time [s]............................10
Record
Output unit ........................Printer
Raw results last sample.............Yes
Results last sample.................Yes
E – V curve.........................Yes
Statistics
Ri (i=index)........................R2
Standard deviation s................Yes
Rel. standard deviation srel........Yes
Outlier test........................Yes
Record
Output unit ........................Printer
Short-form method...................Yes
Sample data.........................Yes
Raw results last sample.............Yes
All results.........................Yes
Table of measured values............Yes
E – V curve.........................Yes
dE/dV – V curve.....................Yes
Conditioning
Interval............................1
Time [s]............................10
METTLER TOLEDO Page 8 of 10 Titration Application M060-2010
Titration Excellence
Back-value determination (H3):
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 060C
Title Back-value
Author METTLER TOLEDO
Date/Time 01.03.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 HCl
Entry type Fixed volume
Volume 10.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Stir
Speed 35%
Duration 10 s
005 Titration (EQP)
Titrant
Titrant HCl
Concentration 0.1 mol/L
Sensor
Type pH
Sensor DGi111-SC
Unit pH
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 5.0 mL
Wait time 10 s
Control
Control User
Titrant addition Dynamic
dE(set) 8.0
dV(min) 0.02 mL
dV(max) 0.2 mL
Meas. val. acquisition Equilibrium controlled
dE 0.5 mV
dt 1.0 s
t(min) 3.0 s
t(max) 30.0 s
Evaluation and recognition
Procedure Standard
Threshold 10 pH/mL
Tendency Negative
Ranges No
Add. EQP criteria No
Termination
At Vmax 15.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EQPs 1
Combined termination
criteria No
006 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle 10.0 mL
Position Current position
007 Calculation R1
Result Back value
Result unit mL
Formula R=Q
Constant C=1
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics No
Extra statistical
functions No
Send to buffer No
008 Auxiliary value
Name H3
Formula Mean[R1]
009 Record
Summary No
Results Per sample
Raw results Per sample
Table of meas. value Last titration function
Sample data No
Ressource data No
E – V Last titration function
dE/dV – V No
log dE/dV – V No
d2E/dV2 – V No
BETA – V No
E – t No
V – t No
dV/dt – t No
T – t No
E-V & dE/dV-V No
V-t & dV/dt-t No
Method No
Series data No
010 End of sample
METTLER TOLEDO Page 9 of 10 Titration Application M060-2010
Fe(II) determination (H2):
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 060
Title Fe(II) determination
. . .
002 Sample
Number of IDs 1
ID 1 Fe+H2SO4
Entry type Fixed volume
Volume 10.0 mL
. . .
003 Titration stand (Rondo/Tower A)
004 Stir
Speed 35%
Duration 10 s
005 Titration (EQP)
Titrant
Titrant 1/6 K2Cr2O7
Concentration 0.1 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 0.5 mL
Wait time 10 s
Control
Control User
Titrant addition Dynamic
dE(set) 8.0
dV(min) 0.02 mL
dV(max) 0.2 mL
Meas. val. acquisition Equilibrium controlled
dE 0.5 mV
dt 1.0 s
t(min) 2.0 s
t(max) 20.0 s
Evaluation and recognition
Procedure Standard
Threshold 200 mV/mL
Tendency Positive
Ranges No
Add. EQP criteria No
Termination
At Vmax 10.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EQPs 1
Combined termination
criteria No
007 Calculation R1
Result Fe concentration
Result unit mol/L
Formula R=2*(Q*C)/m
Constant C=1
M M[None]
z z[None]
Decimal places 4
. . .
008 Calculation R2
Result Fe concentration
Result unit g/L
Formula R2=Q*C2/m
Constant C2=M/z
M M[FeSO4*7H2O]
z z[FeSO4*7H2O]
Decimal places 3
. . .
009 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle 10.0 mL
Position Current position
010 Auxiliary value
Name H2
Formula Mean[R1]
011 Record
Summary No
Results Per sample
Raw results Per sample
Table of meas. value Last titration function
Sample data No
Ressource data No
E – V Last titration function
dE/dV – V No
log dE/dV – V No
d2E/dV2 – V No
BETA – V No
E – t No
V – t No
dV/dt – t No
T – t No
E-V & dE/dV-V No
V-t & dV/dt-t No
Method No
Series data No
012 End of sample
013 Record
Summary Yes
Results Yes
Raw results No
Ressource data No
Calibration curve No
Method No
Series data No
-------------------------------------------------------------
Sample preparation:
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 060A
Title Sample preparation
Author METTLER TOLEDO
Date/Time 01.03.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Fe+H2SO4
Entry type Fixed volume
Volume 5.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Dispense (normal) [1]
Titrant Sample
Concentration 0.1 mol/L
Volume [mL] 5.0
005 Dispense (normal) [2]
Titrant NaOH
Concentration 0.1 mol/L
Volume [mL] 10.0
006 Stir
Speed 60%
Duration 60 s
007 Rinse
Auxiliary reagent Water
Rinse cycles 2
Vol. per cycle 20.0 mL
Position Rinse beaker
Drain Yes
Drain pump SP250
008 End of sample
009 Conditioning
Titration stand Rondo60/1A
Position Conditioning beaker
Time 1200 s
Speed 25%
METTLER TOLEDO Page 10 of 10 Titration Application M060-2010
Acid determination:
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 060B
Title Acid determination
Author METTLER TOLEDO
Date/Time 01.03.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Fe+H2SO4
Entry type Fixed volume
Volume 5.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Stir
Speed 35%
Duration 10 s
005 Titration (EQP)
Titrant
Titrant HCl
Concentration 0.1 mol/L
Sensor
Type pH
Sensor DGi111-SC
Unit pH
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 1.0 mL
Wait time 10 s
Control
Control User
Titrant addition Dynamic
dE(set) 8.0
dV(min) 0.02 mL
dV(max) 0.2 mL
Meas. val. acquisition Equilibrium controlled
dE 0.5 mV
dt 1.0 s
t(min) 3.0 s
t(max) 30.0 s
Evaluation and recognition
Procedure Standard
Threshold 3.0 pH/mL
Tendency Negative
Ranges No
Add. EQP criteria No
Termination
At Vmax 10.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EQPs 1
Combined termination
criteria No
006 Calculation R1
Result Total sum
Result unit mol/L
Formula R=(H[H3]-Q)*C/m
Constant C=1
M M[H2SO4]
z z[H2SO4]
Decimal places 4
Result limits No
Record statistics No
Extra statistical
functions No
Send to buffer No
007 Calculation R2
Result Acid content
Result unit g/L
Formula R2=(R1-H[H2])*C2
Constant C=M/z
M M[H2SO4]
z z[H2SO4]
Decimal places 4
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
008 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle 10.0 mL
Position Current position
009 Conditioning
Titration stand Rondo60/1A
Position Conditioning beaker
Time 10 s
Speed 35%
010 Record
Summary No
Results Per sample
Raw results Per sample
Table of meas. value Last titration function
Sample data No
Ressource data No
E – V Last titration function
dE/dV – V No
log dE/dV – V No
d2E/dV2 – V No
BETA – V No
E – t No
V – t No
dV/dt – t No
T – t No
E-V & dE/dV-V No
V-t & dV/dt-t No
Method No
Series data No
011 End of sample
012 Record
Summary Yes
Results Yes
Raw results No
Ressource data No
Calibration curve No
Method No
Series data No
METTLER TOLEDO Application M463-2010
Determination of Cr(III) by Back Titration in an Electroplating Bath Chromium (III) is determined by back titration of excess cerium(IV) sulphate solution with sodium nitrite.
Preparation and Procedures CAUTION: Work in a fume hood. Use gloves, lab coat and safety goggles. Principle:
Cr(III) is determined as Cr2O3 by back titration of excess cerium(IV) sulphate , Ce(SO4)2, solution.
Back value determination:
1.) Fill up a titration beaker with 50 mL with deionized water.
2.) 1:1 diluted HNO3 and Ce(SO4)2 solution are added with two dosing units.
3.) Ce(IV) is titrated with sodium nitrite. The back value is stored as B[Back] in mmol
Sample titration:
1.) Pipette 2 mL of chromium(III) bath to a beaker and fill up to 50 mL with deionized water.
2.) Sample preparation is automated by adding 1:1 diluted HNO3 and excess Ce(SO4)2 with two dosing units.
3.) Cr(III) is oxidized by excess Ce(IV) to Cr(VI) by the following reaction:
3 Ce4+ + Cr3+ → 3 Ce3+ + Cr6+
4.) Cr(III) is then determined by back titration of unreacted Ce(IV) using sodium nitrite (NaNO2):
2 Ce4+ + NO2- + H2O → 2 Ce3- + NO3
- + 2 H+
Remarks
- It is not necessary to heat the sample as mentioned in older applications.
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- Rinse the electrode after each sample. If necessary, clean the metal ring of the electrode with a paper tissue at the end of each sample series.
Sample 2 mL aliquot of chromium(III) bath (approx. 8 g/L Cr(III))
Compound Cr(III) as Cr2O3 M = 151.99; z = 3
Chemicals - Deionized water - Nitric acid 1:1 - Cerium(IV) sulphate , Ce(SO4)2, c(Ce(SO4)2) = 0.1 mol/L
Titrant Sodium nitrite, NaNO2
c(1/2 NaNO2) = 0.2 mol/L
Standard Cerium(IV) sulphate , Ce(SO4)2
Indication DMi140-SC
Chemistry Cr(III) oxidation by Ce(IV): 3 Ce4+ + Cr3+ → 3 Ce3+ + Cr6+
Back titration of Ce4+: 2 Ce4+ + NO2
- + H2O → 2 Ce3- + NO3
- + 2 H+
Calculation Cr2O3 content in g/L: R=(B[Blank]-Q)*C/m; C = M/(z*2) (2 x Cr in Cr2O3) B[Back] = Back value in mmol Ce(SO4)2
Waste disposal
Heavy metal waste
Author, Version
Susanne Wahlen, MSG Anachem, April 2010
METTLER TOLEDO Page 1 of 4 Titration Application M463-2010
Instruments - T50/70/90 Titration Excellence - XS205 Balance - Rondo 20 Sample Changer
Accessories - 2 x 10 mL DV1010 burette - 1 x 5 mL DV1005 burette - 2 x additional dosing unit - Titration beakers ME-101974 - LabX titration pro
Results METTLER TOLEDO T90
Method: 002 CHROM(III) 16.04.2010 17:07:54
Results
Series start time 16.04.2010 17:08:37
No. Note / ID Start time Rx Result Unit Name
1/6 Cr2O3 16.04.2010 17:08:33 R1 = 2.018 mL Consumption
R2 = 7.314 (2) g/L Chromium(III)oxide
2/6 Cr2O3 16.04.2010 17:20:33 R1 = 2.037 mL Consumption
R2 = 7.265 g/L Chromium(III)oxide
3/6 Cr2O3 16.04.2010 17:32:48 R1 = 2.048 mL Consumption
R2 = 7.237 g/L Chromium(III)oxide
4/6 Cr2O3 16.04.2010 17:45:02 R1 = 2.055 mL Consumption
R2 = 7.221 g/L Chromium(III)oxide
5/6 Cr2O3 16.04.2010 17:57:14 R1 = 2.044 mL Consumption
R2 = 7.247 g/L Chromium(III)oxide
6/6 Cr2O3 16.04.2010 18:09:31 R1 = 2.052 mL Consumption
R2 = 7.228 g/L Chromium(III)oxide
Statistics: n = 5 R2 = 7.240 ± 0.018 g/L s = 0.0172 srel: 0.238% (2) excluded
Titration curve
Sample 2/6
METTLER TOLEDO Page 2 of 4 Titration Application M463-2010
METTLER TOLEDO Page 3 of 4 Titration Application M463-2010
Table of measured values
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL min:s -------------------------------------------------------------------------------------------- 0 1291.3 0 0.02 0.02 1290.7 -0.6 3 0.04 0.02 1290.2 -0.5 6 0.09 0.05 1289 -1.2 9 0.215 0.125 1286.2 -2.8 12 0.415 0.2 1281.4 -4.8 -23.91 15 0.615 0.2 1276.3 -5.1 -25.16 18 0.815 0.2 1271 -5.3 -27.73 21 1.015 0.2 1264.8 -6.2 -32.32 24 1.215 0.2 1257.7 -7.1 -40.05 28 1.415 0.2 1249 -8.7 -53.77 32 1.583 0.168 1239.7 -9.3 -75.21 36 1.696 0.113 1231.5 -8.2 -101.42 41 1.7815 0.0855 1223.4 -8.1 -136.73 46 1.8455 0.064 1215.2 -8.2 -188.09 51 1.8915 0.046 1207.4 -7.8 -280.21 58 1.9275 0.036 1199.4 -8 -475.65 65 1.955 0.0275 1190.8 -8.6 -755.81 73 1.975 0.02 1182.4 -8.4 -917.64 83 1.995 0.02 1170.1 -12.3 -1512.53 96 2.015 0.02 1144.1 -26 -1876.36 125 2.035 0.02 1086 -58.1 -1570.8 155 EQP1 2.036912 1077.8 -1935.31 2.055 0.02 999.7 -86.3 -1302.36 185 2.075 0.02 982.9 -16.8 -1232.25 200 2.124 0.049 965.5 -17.4 -829.18 211 2.177 0.053 954.6 -10.9 220 2.2445 0.0675 945.6 -9 226 2.3375 0.093 936.9 -8.7 233 2.4595 0.122 929.1 -7.8 239 2.6405 0.181 921 -8.1 244
Comments
--
METTLER TOLEDO Page 4 of 4 Titration Application M463-2010
Method 001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 002
Title CHROM(III)
Author Administrator
Date/Time 13.04.2010 14:45:58
Modified at 16.04.2010 17:07:54
Modified by admin
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Cr2O3
Entry type Fixed volume
Volume [mL] 2.0
Density [g/mL] 1.0
Correction factor 1.0
Temperature 25.0
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
LidHandling No
004 Stir
Speed [%] 30
Duration [s] 2
Condition No
005 Dispense (normal) [1]
Titrant HNO3 (1 :1)
Concentration [mol/L] 1
Volume [mL] 5.0
Dosing rate [mL/min] 60.0
Condition no
006 Dispense (normal) [2]
Titrant Ce(SO4)2
Concentration [mol/L] 0.1
Volume [mL] 10.0
Dosing rate [mL/min] 60.0
Condition no
007 Stir
Speed [%] 30
Duration [s] 300
Condition No
008 Titration (EQP) [1]
Titrant
Titrant ½ NaNO2
Concentration [mol/L] 0.2
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed [%] 30
Predispense
Mode None
Waiting time [s] 0
Control
Control User
Titrant addition Dynamic
dE (set value) [mV] 8.0
dV (min) [mL] 0.02
dV (max) [mL] 0.2
Mode Equilibrium controlled
dE [mV] 0.5
dt [s] 1.0
t(min) [s] 3.0
t(max) [s] 30
Evaluation and recognition
Procedure Standard
Threshold 200.0
Tendency Negative
Ranges 0
Add. EQP criteria No
Termination
At Vmax 20
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating
Accompanying stating No
Condition
Condition No
009 Calculation R1
Result Consumption
Result unit mL
Formula R1=VEQ
Constant C= 1
M M[none]
z z[None]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
010 Calculation R2
Result Chromium(III)oxide
Result unit g/L
Formula R2=(B[Back]-Q)*C/m
Constant C= M/(z*2)
M M[Cr2O3]
z z[Cr2O3]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
011 Record
Summary No
Results Per sample
Raw results Per sample
Table of meas. values Last titration function
Sample data No
Resource data No
E - V Last titration function
dE/dV - V Last titration function
log dE/dV - V No
d2E/dV2 - V No
BETA – V No
E - t No
V - t No
dV/dt - t No
T – t No
E – V & dE/dV – V No
V – t & dV/dt – t No
Method No
Series data No
Condition No
012 End of sample
METTLER TOLEDO Application M464-2010
Iodometric Titration of Cr(VI) in an Electroplating Bath Chromium is determined by redox titration of free iodine generated by reduction of Cr(VI) to Cr(III) with potassium iodide. Iodine is titrated with sodium thiosulfate and a combined platinum ring sensor.
Preparation and Procedures CAUTION:
Work in a fume hood. Use gloves, lab coat and safety goggles.
Sample titration:
- 2.5 mL chromium bath is diluted with deionized water to 250 mL. 5 mL of diluted aliquot corresponds to 0.05 mL of original sample. The latter value is defined as fixed sample volume.
- Sulphuric acid is automatically added by a dosing unit.
- The addition of potassium iodide KI by a pump leads to the reduction of Cr(VI) to Cr(III) according to the following reaction: 2 Cr6+ + 6I- = 2 Cr3+ + 3 I2 (z = 3)
- The amount of iodine formed is proportional to the Cr(VI) content.
- Generated I2 is then titrated with Na2S2O3: 2 S2O3
2- + I2 = S4O62- + 2 I-
Note: Stir moderately. Vigorous stirring causes loss of I2.
Remarks
- 1 mL Na2S2O3 corresponds to 3.33 mg CrO3.
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- Rinse the electrode after each sample.
- If necessary, clean the metal ring of the sensor with a paper tissue at the end of each sample series.
Sample 5 mL aliquot from 1:100 diluted chromium(VI) bath
Compound Cr(VI) as CrO3 M = 99.99; z = 3
Chemicals - Deionized water - Sulphuric acid, 1:1 - Potassium iodide solution, KI 10% KI
Titrant Sodium thiosulphate, Na2S2O3
c(Na2S2O3)=0.1 mol/L
Standard Potassium iodate, KIO3
Indication DMi140-SC
Chemistry Cr(VI) reduction to Cr(III): 2 Cr6+ + 6I- → 2 Cr3+ + 3 I2
Titration of iodine: 2 S2O3
2+ + I2 → S4O62- + 2 I-
Calculation CrO3 content in g/L: R=Q*C/m C=M/z
Waste disposal
Heavy metal waste
Author, Version
Susanne Wahlen, MSG Anachem, April 2010
METTLER TOLEDO Page 1 of 4 Titration Application M464-2010
Instruments - T50/70/90 Titration Excellence - XS205 Balance - Rondo 20 Sample Changer - SP250 Peristaltic pump ME-51108016
Accessories - 2 x 10 mL DV1010 burette - 1 x additional burette drive - Titration beakers ME-101974 - LabX titration pro
Results METTLER TOLEDO T90
DL90 Fumehood
Method: 001 CHROMIUM(VI) 15.04.2010 17:06:09
Results
Series start time 15.04.2010 16:06:37
No. Note / ID Start time Rx Result Unit Name
1/8 CrO3 15.04.2010 16:06:38 R1 = 4.381 mL Consumption
R2 = 292.065 g/L Chromium(VI)oxide
2/8 CrO3 15.04.2010 16:13:56 R1 = 4.381 mL Consumption
R2 = 292.051 g/L Chromium(VI)oxide
3/8 CrO3 15.04.2010 16:21:11 R1 = 4.428 mL Consumption
R2 = 295.143 g/L Chromium(VI)oxide
4/8 CrO3 15.04.2010 16:28:28 R1 = 4.432 mL Consumption
R2 = 295.412 g/L Chromium(VI)oxide
5/8 CrO3 15.04.2010 16:35:46 R1 = 4.532 mL Consumption
R2 = 302.104 (2) g/L Chromium(VI)oxide
6/8 CrO3 15.04.2010 16:43:11 R1 = 4.269 mL Consumption
R2 = 284.538 (2) g/L Chromium(VI)oxide
7/8 CrO3 15.04.2010 16:50:20 R1 = 4.368 mL Consumption
R2 = 291.178 g/L Chromium(VI)oxide
8/8 CrO3 15.04.2010 16:57:35 R1 = 4.357 mL Consumption
R2 = 290.468 % Chromium(VI)oxide
Statistics: n = 6 R2 = 292.719 ± 2.071 g/L s = 2.071 srel: 0.707% (2) excluded
Titration curve
Sample 2/8
METTLER TOLEDO Page 2 of 4 Titration Application M464-2010
METTLER TOLEDO Page 3 of 4 Titration Application M464-2010
Table of measured values
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL min:s -------------------------------------------------------------------------------------------- 0 NaN 355.9 NaN NaN 0 2 2 346.5 -9.4 NaN 6 2.05 0.05 346.4 -0.1 NaN 9 2.1 0.05 346.1 -0.3 NaN 12 2.15 0.05 345.8 -0.3 NaN 15 2.2 0.05 345.5 -0.3 -5.91 18 2.25 0.05 345.2 -0.3 -6.63 22 2.3 0.05 344.9 -0.3 -6.6 25 2.35 0.05 344.5 -0.4 -6.8 28 2.4 0.05 344.2 -0.3 -7 31 . . . . . . . . . . . . . . . . . . 3.1 0.05 338.3 -0.5 -10.28 73 4 0.05 323 -1.5 -30.8 128 4.05 0.05 321.4 -1.6 -34.63 131 4.1 0.05 319.5 -1.9 -39.51 134 4.15 0.05 317.2 -2.3 -40.39 137 4.2 0.05 314.5 -2.7 22.69 140 4.25 0.05 311.2 -3.3 -78.76 144 4.3 0.05 306.7 -4.5 -286.78 147 4.35 0.05 300.2 -6.5 -501.86 150 4.4 0.05 285.7 -14.5 -643.36 154 EQP1 4.431621 NaN 233.7 NaN -667.44 NaN 4.45 0.05 203.5 -82.2 -665.73 164 4.5 0.05 178.9 -24.6 -560.11 175 4.55 0.05 168.9 -10 -360.3 182 4.6 0.05 163 -5.9 -138.14 188 4.65 0.05 158.7 -4.3 2.37 192 4.7 0.05 155.9 -2.8 NaN 195 4.75 0.05 153.2 -2.7 NaN 198 4.8 0.05 150.8 -2.4 NaN 202 4.85 0.05 148.7 -2.1 NaN 204 4.9 0.05 146.8 -1.9 NaN 208
Comments
--
METTLER TOLEDO Page 4 of 4 Titration Application M464-2010
Method 001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 001
Title Chromium(VI)
Author Administrator
Date/Time 13.04.2010 10:32:13
Modified at 23.04.2010 12:23:15
Modified by admin
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 CrO3
Entry type Fixed volume
Volume [mL] 0.05
Density [g/mL] 1.0
Correction factor 1.0
Temperature 25.0
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo20/1A
Lid Handling No
004 Dispense (normal) [1]
Titrant H2SO4 1:1
Concentration 4.6
Volume [mL] 5.0
Dosing rate [mL/min] 60.0
Condition no
005 Pump
Auxiliary reagent Water
Volume [mL] 40.0
Condition no
006 Pump
Auxiliary reagent KI
Volume [mL] 5.0
Condition No
007 Stir
Speed [%] 30
Duration [s] 90
Condition No
008 Titration (EQP) [1]
Titrant
Titrant Na2S2O3
Concentration [mol/L] 0.1 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed [%] 30
Predispense
Mode Volume
Volume [mL] 2.0
Waiting time [s] 0
Control
Control User
Titrant addition Incremental
dV [mL] 0.05
Mode Equilibrium controlled
dE [mV] 1.0
dt [s] 2.0
t(min) [s] 3.0
t(max) [s] 10.0
Evaluation and recognition
Procedure Standard
Threshold 200.0
Tendency Negative
Ranges 0
Add. EQP criteria No
Termination
At Vmax 10
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
009 Calculation R1
Result Consumption
Result unit mL
Formula R1=VEQ
Constant C= 1
M M[none]
z z[None]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
010 Calculation R2
Result Chromium(VI)oxide
Result unit g/L
Formula R2=Q*C/m
Constant C= M/z
M M[Chromium(VI)oxide]
z z[Chromium(VI)oxide]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
011 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle [mL] 10
Position Current position
Drain No
Condition No
012 End of sample
013 Park
Titration stand Rondo20/1A
Position Rinse beaker
Condition No
METTLER TOLEDO Application M461-2010 Determination of Manganese in Manganese Ores
Manganese is determined in slighlty acidic-neutral digested solutions by redox titration at 80°C with potassium permanganate KMnO4 as a titrant. The potential change is monitored by a combined platinum ring electrode.
Preparation and Procedures CAUTION: Work in a fume hood, use safety goggles and wear gloves.
Note: Check under “Comments and method” for the dissolution of manganese ores Sample preparation with pure MnO2:
- Approximately 0.5 g pure (> 99.9%) MnO2 is accurately weighed into a glass titration beaker.
- 20 mL deionized water HCl is added. - 30 mL 32% concentrated HCl is added. - The sample is heated (70-90°C) on a hot plate
under stirring to dissolve manganese dioxide. - After complete dissolution, the solution is cooled
to room temperature and is added into a 500 mL volumetric flask.
- Add deionized water to approx. 450 mL, gently shake the solution. If necessary, neutralize with Na2CO3 up to a neutral or slightly acidic solution.
- Fill up to the mark with deionized water.
Titration of Mn(II):
- 5 mL of the digested solution is added into a glass titration beaker.
- Add 60 mL deionized water. - Add 3 mL 10% ZnO suspension, and 5 mL
ZnSO4. - Start immediately the titration with KMnO4.
Remarks
- The content determination is based on a comparative titration of a standard solution. Thus, two titrations are performed: 1) Calibration titration with std. solution of known concentration, where a factor in mg/mL MnO2 is determined. 2) Content determination
- Perform both the calibration and sample titrations under exactly the same conditions.
- In this application, pure manganese dioxide has been used to prepare a digested ore sample.
- The parameters have been optimized for this application. It may be necessary to adapt the method to your sample.
Sample Manganese (IV) dioxide acid digested solution, MnO2 (approx. 0.5 g/500 mL) 5 mL
Compound Manganese, MnO2
M = 86.94; z = 2
Chemicals 32% hydrochloric acid, HCl
10% zinc oxide suspension, (ZnO in water)
ZnSO4 (10g/200 mL H2O)
Deionized water
Titrant Potassium permanganate, KMnO4 c(1/3 KMnO4) = 0.06 mol/L
Standard Sodium oxalate, Na2C2O4
(for 1/5 KMnO4), 0.025-0.040 g
Indication Combined redox Pt-electrode e.g. DMi140-SC
Chemistry Digestion and reduction to Mn(II): MnO2 + 4 HCl → MnCl2 + Cl2 + 2 H2O
Titration from Mn(II) to Mn(IV): 3 Mn2+ + 2 MnO4
- + 2 ZnO → 5 MnO2 + 2 Zn2+
Auxiliary reaction (masking of iron): 2 Fe3+ + 3 ZnO + 3 H2O → 2 Fe(OH)3 + 3 Zn2+
Calculation Content (%, as Mn): R1 = Q*C/m C = M/(10*z)
Waste disposal
Neutralize with sodium hydroxide before final disposal as metal solution.
Author, Version
Cosimo De Caro, MSG Anachem, April 2010
METTLER TOLEDO Page 1 of 8 Titration Application M461-2010
METTLER TOLEDO Page 2 of 8 Titration Application M461-2010
Instruments - T50/T70/T90 Titration Excellence - XS205 Balance - DH100 heating system - Rondo 20 sample changer
Accessories - 1 x 10 mL DV1010 burette - Glass titration beaker ME-101446 - LabX pro titration software
Calibration factor: Results
Sample Factor (mg/mL)
n srel (%)
ZnO H2O
mL mL Parameters INC TFIX mL s
Acid digested MnO2
solution, 5 mL (5.118 mg MnO
2)
2.863 ± 0.067
2.988 ± 0.052
2.866 ± 0.018
2.743 ± 0.025
2.950 ± 0.041
3.015 ± 0.024
2.980 ± 0.024
3.016 ± 0.063
6 2.345
6 1.726
6 0.626
6 0.924
6 1.381
6 0.802
6 0.812
6 1.095
3 60
3 60
3 60
3 60
3 60
3 60
3 60
20 40
0.1 30 80°C manual
0.1 15 80°C manual
0.1 30 80°C Rondo20
0.1 15 60°C Rondo20
0.1 30 80°C Rondo20, 0.7 mL predisp.
0.05 30 80°C Rondo20, 1 mL predisp.
0.1 15 80°C Rondo20 12 days later
0.1 45 80°C Rondo20
Acid digested MnO2
solution, 5 mL (5.368 mg MnO
2)
3.010 ± 0.030
3.041 ± 0.058
2.997 ± 0.048
6 0.999
4 1.905
4 1.600
10 50
10 60
5 60
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20
0.02-1 mL, EQU: 0.5/3 mV/s, t=15-45 s
Standard solution MnSO
4 x H
2O in H
2O
5 mL
(9.576 mg MnSO4 x H2O)
7.242 ± 0.184
6.446 ± 0.144
5.709 ± 0.213
5.690 ± 0.142
5 2.545
6 2.242
5 3.724
5 2.504
5 60
5 60
3 60
3 60
0.1 30 80°C Rondo20 No acid
0.1 30 80°C Rondo20 1 mL 0.5 M HCl
0.1 30 80°C Rondo20 1 mL 0.5 M HCl 5 mL ZnSO4 (10g/200 mL H2O)
0.1 30 80°C Rondo20 1 mL 0.5 M HCl 5 mL ZnSO4 (10g/200 mL H2O) Conditioning: 0.5 M HCl
5.689 ± 0.087
5.994 ± 0.141
6.019 ± 0.039
3 1.535
3 2.357
3 0.654
5 50
1 60
3 60
0.1 5 80°C Rondo20 10 mL ZnSO4 (10g/200 mL H2O Conditioning: H2O
0.1 5 80°C Rondo20 3 mL ZnSO4 (10g/200 mL H2O) Conditioning: H2O 0.1 5 80°C Rondo20 5 mL ZnSO4 (10g/200 mL H2O) Conditioning: H2O
Note:
- When using less than 3 mL ZnO suspension no titration was possible. With more than 3 mL, the result is more or less constant.
- A variation of several parameters such as the titration method parameters (increments, titration modes, signal acquisition,..) and sample preparation (use of Mg standard solution, pH neutral sample solution,…) did not show any significant influence on the results.
Calibration factor: Titration curve
Sample 1/6 - 8.4.2010 09:02 CDCMnOMnO2RONDO
Calibration factor: Table of measured values
Volume Increment Signal Change 1st deriv. Time Temperature mL mL mV mV mV/mL s °C -------------------------------------------------------------------------------------- 0.0000 NaN 393.7 NaN NaN 0 25.0 0.1000 0.1000 407.0 13.3 NaN 30 25.0 0.2000 0.1000 415.5 8.5 NaN 60 25.0 0.3000 0.1000 418.6 3.1 NaN 90 25.0 0.4000 0.1000 425.4 6.8 NaN 121 25.0 0.5000 0.1000 430.0 4.6 44.67 151 25.0 0.6000 0.1000 434.2 4.2 51.44 181 25.0 0.7000 0.1000 440.1 5.9 55.84 211 25.0 0.8000 0.1000 448.4 8.3 54.58 241 25.0 0.9000 0.1000 447.6 -0.8 57.50 272 25.0 1.0000 0.1000 459.9 12.3 52.96 302 25.0 1.1000 0.1000 462.2 2.3 46.86 332 25.0 1.2000 0.1000 467.1 4.9 39.99 362 25.0 1.3000 0.1000 473.4 6.3 29.44 392 25.0 1.4000 0.1000 476.0 2.6 69.54 422 25.0 1.5000 0.1000 484.9 8.9 165.42 452 25.0 1.6000 0.1000 497.0 12.1 275.11 483 25.0 1.7000 0.1000 523.3 26.3 350.54 513 25.0 EQP1 1.764479 NaN 562.9 NaN 365.64 NaN NaN 1.8000 0.1000 584.7 61.4 363.09 543 25.0 1.9000 0.1000 620.4 35.7 303.67 573 25.0 2.0000 0.1000 644.0 23.6 191.62 603 25.0 2.1000 0.1000 644.3 0.3 57.39 634 25.0 2.2000 0.1000 644.7 0.4 -50.26 664 25.0 2.3000 0.1000 640.6 -4.1 NaN 694 25.0 2.4000 0.1000 630.8 -9.8 NaN 724 25.0 2.5000 0.1000 619.4 -11.4 NaN 754 25.0 2.6000 0.1000 609.0 -10.4 NaN 784 25.0 2.7000 0.1000 605.8 -3.2 NaN 815 25.0 Sample 1/6 - 8.4.2010 09:02 CDCMnOMnO2RONDO
METTLER TOLEDO Page 3 of 8 Titration Application M461-2010
METTLER TOLEDO Page 4 of 8 Titration Application M461-2010
Sample determination: Results
Calibration factor:
Sample Factor (mg/mL)
n srel (%)
ZnO H2O
mL mL Parameters INC TFIX mL s
Acid digested MnO
2 solution,
5 mL (5.118 mg MnO
2)
2.863 ± 0.067
2.866 ± 0.018
2.950 ± 0.041
6 2.345
6 0.626
6 1.381
3 60
3 60
3 60
0.1 30 80°C manual
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20, 0.7 mL predisp.
Average calibration factor
2.893 ± 0.049 3 1.707
Sample determination:
Sample Consumption (mL) Recovery rate (%)
ZnO H2O
mL mL Parameters INC TFIX mL s
Acid digested MnO
2 solution,
5 mL (5.118 mg MnO
2)
Sample Series (9) 24.03.2010 12:25
1/6
2/6
3/6
4/6
5/6
6/6
1.774
1.774
1.781
1.799
1.798
1.787
100.28
100.28
100.67
101.69
101.63
101.01
3 60
3 60
3 60
3 60
3 60
3 60
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20
0.1 30 80°C Rondo20
Average (%) 100.93
Std. deviation (%)
0.630
Rel. Std. dev. (%)
0.624
Sample Series (8) 25.03.2010 09:19
1/6
2/6
3/6
4/6
5/6
6/6
1.706
1.731
1.778
1.723
1.741
1.733
96.43
97.85
100.50
97.39
98.41
97.96
3 60
3 60
3 60
3 60
3 60
3 60
0.1 30 80°C Rondo20, 0.7 mL predispensing
0.1 30 80°C Rondo20, 0.7 mL predispensing
0.1 30 80°C Rondo20, 0.7 mL predispensing
0.1 30 80°C Rondo20, 0.7 mL predispensing
0.1 30 80°C Rondo20, 0.7 mL predispensing
0.1 30 80°C Rondo20, 0.7 mL predispensing
Average (%) 98.09
Std. deviation (%)
1.359
Rel. Std. dev. (%)
1.385
Sample determination: Titration curve
Sample 6/6 – 24.3.2010 12:25 CDCMnOMnO2RONDO2 (9)
Sample determination: Table of measured values
Volume Increment Signal Change 1st deriv. Time Temperature mL mL mV mV mV/mL s °C -------------------------------------------------------------------------------------- 0.0000 NaN 430.6 NaN NaN 0 25.0 0.1000 0.1000 429.7 -0.9 NaN 30 25.0 0.2000 0.1000 428.5 -1.2 NaN 60 25.0 0.3000 0.1000 430.5 2.0 NaN 91 25.0 0.4000 0.1000 431.2 0.7 NaN 121 25.0 0.5000 0.1000 431.4 0.2 7.83 151 25.0 0.6000 0.1000 430.7 -0.7 6.44 181 25.0 0.7000 0.1000 433.3 2.6 6.78 211 25.0 0.8000 0.1000 433.7 0.4 10.33 242 25.0 0.9000 0.1000 434.4 0.7 12.53 272 25.0 1.0000 0.1000 435.2 0.8 14.11 302 25.0 1.1000 0.1000 438.2 3.0 17.03 332 25.0 1.2000 0.1000 439.5 1.3 21.44 362 25.0 1.3000 0.1000 441.6 2.1 -21.34 392 25.0 1.4000 0.1000 445.0 3.4 -0.37 423 25.0 1.5000 0.1000 449.4 4.4 140.21 453 25.0 1.60000 0.1000 453.6 4.2 298.77 483 25.0 1.7000 0.1000 462.4 8.8 410.61 513 25.0 EQP1 1.787293 NaN 542.9 NaN 445.71 NaN NaN 1.8000 0.1000 554.6 92.2 445.67 543 25.0 1.9000 0.1000 626.3 71.7 393.96 574 25.0 2.0000 0.1000 626.4 0.1 268.65 604 25.0 2.1000 0.1000 632.8 6.4 112.76 634 25.0 2.2000 0.1000 640.2 7.4 -0.71 664 25.0 2.3000 0.1000 644.8 4.6 NaN 694 25.0 2.4000 0.1000 647.9 3.1 NaN 724 25.0 2.5000 0.1000 652.2 4.3 NaN 754 25.0 2.6000 0.1000 656.2 4.0 NaN 785 25.0 2.7000 0.1000 657.0 0.8 NaN 815 25.0 Sample 6/6 – 24.3.2010 12:25 CDCMnOMnO2RONDO2 (9)
METTLER TOLEDO Page 5 of 8 Titration Application M461-2010
METTLER TOLEDO Page 6 of 8 Titration Application M461-2010
Comments and Methods
• A direct titration always leads to lower content values (see below). Thus, the determination of manganese in ores is based on a comparative titration between a standard and the sample solution:
1. First, the titrant consumption for the titration of a standard solution of known concentration is determined. The result is stored as auxiliary value H[CalibFactorMn] in mg/mL MnO2. A known amount of MnO2 is digested in acid in order to get Mn(II)-ions into solution.
2. Subsequently, the titrant consumption for the sample is determined. The result is obtained by multiplying the calibration factor H[CalibFactorMn] with the titrant consumption.
• Only a slight excess of ZnO suspension is needed.
• It is very important that both titrations are performed exactly in the same way i.e. stirring speed, T,…
Manganese ore dissolution: In this application, the titration has been performed using acid digested solution of MnO. The application can be also run with manganese ores. A customer procedure for the dissolution of manganese ores is as it follows: - Weigh 0.1 g of dried sample in a platinum crucible and 2 g of Na2CO3; - Leave the crucible in a muffle oven at 700°C, raise the temperature until 950°C and leave it during 20min; - Remove the sample and wait until the sample is cooled down; - Dissolve the molten mass in a 250 mL beaker with 50mL 1:1 HCl on a hot plate at 100°C and shake; - Transfer to an 1000mL Erlenmeyer flask and leave on a hot plate at 250°C until the volume is reduced to 10mL.
Subsequently, leave it on the hot plate at 100°C until dryness; - Add 700 mL of hot water and leave to boil on the hot plate; - Add sufficient 10% (w/w) ZnO suspension until the solution turns white, and titrate in the heat with KMnO4 to EQP.
Chemical reaction: Mn(II) is titrated by permanganate titration at 80°C in a neutral or slightly acidic solution leading to the formation of Mn(IV) according to the reaction
3 Mn2+ + 2 MnO4- + 2 ZnO → 5 MnO2 + 2 Zn2+
In iron-manganese ores or in manganese alloys, iron needs to be masked since it affects the manganese determination. This is done by precipitating iron with zinc oxide.
2 Fe3+ + 3 ZnO + 3 H2O → 2 Fe(OH)3 + 3 Zn2+
A detailed analysis of the chemical reaction shows that Mn(IV) is precipitated as manganese oxyde hydrate, MnO2·H2O, a dark brown compound which is clearly visible in the solution:
2 MnO4- + 3 Mn2+ + 7 H2O → 5 MnO2·H2O + 4 H+
The formation of manganese oxyde hydrate leads to adsorption of bivalent ions such as Mn(II) and Zn(II). If unreacted Mn(II) is adsorbed, then mixed Mn(II)-Mn(IV) oxide hydrate with formula Mn(HMnO3)2 is precipitated. As a consequence, the titrant consumption is smaller than expected. To avoid it, ZnO suspension and also ZnSO4 solution are added. Thus, the addition of excess ZnO suspension is needed to first neutralize the resulting acid protons, to mask iron, and also to suppress adsorption and co-precipitation of unreacted Mn(II).
Nevertheless, the oxidation of Mn(II) to Mn(IV) seems still not to be complete when reaching the equivalence point. Thus, it is necessary to heat again to 80°C the titrated solution, then continues the analysis until the equivalence point is reached again. For this reason, a comparative titration is more suitable for routine analysis.
Literature: [1] www.chemguide.co.uk/inorganic/transition/manganese.html, and www.titrations.info/permanganate-titration . [2] Jander Jahr, “Massanalyse”, ed. by Gerhard Schulze and Jürgen Simon, 14th Edition, de Gruyter, 1986 (German). [2] Othmar G. Koch, „Analytische Chemie des mangans“, Springer-Verlag, 1985 (German). [4] József Mika, „Metallurgische Analysen”, Akademische Verlagsgesellschaft, Geest & Portig K.-G., Leipzig 1964
(German).
METTLER TOLEDO Page 7 of 8 Titration Application M461-2010
Calibration factor
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID m461Calib
Title Calibration factor Mn
Author METTLER TOLEDO
Date/Time 01.06.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 MnO2 Standard solution
Entry type Fixed volume
Volume 5.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Stir
Speed 50%
Duration 60 s
005 Auxiliary instrument
Control type Out TTL (Single pin)
Name DH100 TTL on
Mode Fixed time
Time 2 s
006 Measure (normal) [1]
Sensor
Type Temperature
Sensor DT1000
Unit °C
Stir
Speed 50%
Acquisition of measured values
Acquisition Set value
Mode T>set value
Set value 80°C
t(max) 300
Mean value No
007 Titration (EQP) [1]
Titrant
Titrant 1/3 KMnO4
Concentration 0.06 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 50%
Predispense
Mode None
Wait time 0 s
Control
Control User
Titrant addition Incremental
dV 0.1 mL
Meas. val. acquisition Fixed time
dt 30 s
Evaluation and recognition
Procedure Standard
Threshold 150 mV/mL
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 10.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EQPs 1
Combined termination
criteria No
008 Auxiliary instrument
Control type Out TTL (Single pin)
Name DH100 TTL off
Mode Fixed time
Time 2 s
009 Calculation R1
Result Consumption
Result unit mL
Formula R=VEQ
Constant C=1
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
010 Calculation R2
Result Calibration factor
Result unit mg/mL
Formula R2=(C*m)/VEQ
Constant C=H[MnO2Std]
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics No
Extra statistical
functions No
Send to buffer No
011 Rinse
Titration stand Rondo60/1A
Auxiliary reagent Water
Rinse cycles 1
Vol.per cycle 20
Position Current position
Drain No
012 Conditioning
Titration stand Rondo60/1A
Type Fix
Interval 1
Position Conditioning beaker
Time 60 s
Speed 70%
013 End of sample
014 Auxiliary value
Name CalibFactor
Formula H= Mean[R2]
--------------------------------------------------------------
Calculation R2: C: H[MnO2Std] Concentration of the digested MnO2 standard solution e.g. 0.5118 g MnO2 in 500 mL H = 0.5118/500 = 0.0010236 g/mL = 1.0236 mg/mL
METTLER TOLEDO Page 8 of 8 Titration Application M461-2010
Sample titration
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID m461sample
Title Sample titration Mn
Author METTLER TOLEDO
Date/Time 01.06.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Digested ore solution
Entry type Fixed volume
Volume 5.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
004 Stir
Speed 50%
Duration 60 s
005 Auxiliary instrument
Control type Out TTL (Single pin)
Name DH100 TTL on
Mode Fixed time
Time 2 s
006 Measure (normal) [1]
Sensor
Type Temperature
Sensor DT1000
Unit °C
Stir
Speed 50%
Acquisition of measured values
Acquisition Set value
Mode T>set value
Set value 80°C
t(max) 300
Mean value No
007 Titration (EQP) [1]
Titrant
Titrant 1/3 KMnO4
Concentration 0.06 mol/L
Sensor
Type mV
Sensor DMi140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 50%
Predispense
Mode None
Wait time 0 s
Control
Control User
Titrant addition Incremental
dV 0.1 mL
Meas. val. acquisition Fixed time
dt 30 s
Evaluation and recognition
Procedure Standard
Threshold 150 mV/mL
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 10.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number EQPs 1
Combined termination
criteria No
008 Auxiliary instrument
Control type Out TTL (Single pin)
Name DH100 TTL off
Mode Fixed time
Time 2 s
009 Calculation R1
Result Consumption
Result unit mL
Formula R=VEQ
Constant C=1
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
010 Calculation R2
Result MnO2 Amount
Result unit mg
Formula R2=H[CalibFactor]*VEQ
Constant C=1
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics No
Extra statistical
functions No
Send to buffer No
011 Calculation R3
Result MnO2 Content
Result unit %
Formula R3=((R2/1000)/H[Ore])*100
Constant C=H[Ore]
M M[MnO2]
z z[MnO2]
Decimal places 3
Result limits No
Record statistics No
Extra statistical
functions No
Send to buffer No
012 Rinse
Titration stand Rondo60/1A
Auxiliary reagent Water
Rinse cycles 1
Vol.per cycle 20
Position Current position
Drain No
013 Conditioning
Titration stand Rondo60/1A
Type Fix
Interval 1
Position Conditioning beaker
Time 60 s
Speed 70%
014 End of sample
METTLER TOLEDO Application M466A-2010
Aluminum Content in Aluminum Ore (Bauxite) – Bayer Liquor Determination of free alkali and aluminum content in aluminum ore (Bauxite) by potentiometric titration with hydrochloric acid according to the Bayer procedure. The titration is monitored with a pH glass combined sensor.
Preparation and Procedures
CAUTION: Work in a fume hood and wear gloves and safety goggles.
- Weight in about 30 gr into a 600 mL Erlenmeyer flask.
- Add 350 mL 7 mol/L NaOH and cover it with a watch glass.
- Heat the sample on a heating plate set at 200°C, and keep it boiling while continuously stirring for at least 4 hours.
- The alumina is first converted into aluminum hydroxide, Al(OH)3, and further to [Al(OH)4]-
which is dissolved in the hydroxide solution.
- Some components are not dissolved; these are mainly insoluble iron hydroxide compounds.
- Let the solution cool down; prepare a 500 ml volumetric flask with a glass funnel and a paper filter to avoid the solid impurities.
- Filter the cooled solution into the 500 mL volumetric flask.
- Wash the paper filter with 100 mL 7 M NaOH.
- Mix well and fill up to the mark with deionized water, and mix again. Note: Temperature can increase again; thus, filling with water may be necessary again.
- 5 mL sample solution is added to a titration beaker together with 35 mL deion. water.
Remarks
- Rinsing and conditioning of the pH sensor is crucial to achieve accurate and precise results. In fact, the pH sensor is titrating in a strong alkaline solution (pH > 12).
- The parameters have been optimized for this specific sample solution. It may be necessary to adapt the method to your sample.
- The %-content Al2O3 is calculated from the mg/g-content Al(OH)3 (see R4) by multiplying it with a conversion factor from the ratio between M(Al2O3) and M(Al(OH3)) (see R5).
Sample 5 mL alkaline digestion solution from original aluminum ore (Bayer Liquor, 30.23 g/500 mL)
Compound Aluminum trihydroxide, Al(OH)3 M = 78.00 g/mol, z = 3 Sodium hydroxide, NaOH M = 40.00 g/mol, z = 1
Chemicals 25% Na-gluconate, NaC6H11O7 30% Potassium fluoride, KF Deionized water (see Preparation and
Titrant Hydrochloric acid, HCl c(HCl) = 1 mol/L c(HCl) = 0.1 mol/L
Standard Tris(hydroxymethyl)-aminomethane, THAM
Indication DGi115-SC
Chemistry OH- + H3O+ → 2 H2O see “Comments” for more detailed information
Calculation Free Caustic NaOH (g/L): R1 = (Q-Q2)*C/m ; C=M/z Free Carbonate CaCO3 (g/L): R2 = Q2*C/m ; C=M/z Aluminum hydroxide Al(OH)3 (g/L): R3 = (Q[2]+QEX)*C/m ; C = M/z, M = 78.00 , z = 3 (see “Comments”)
Waste
disposal
After neutralization dispose the sample solution as heavy metals.
Author,
Version
Cosimo De Caro MSG Anachem, July 2010
METTLER TOLEDO Page 1 of 7 Titration Application M466A-2010
METTLER TOLEDO Page 2 of 7 Titration Application M466A-2010
Instruments - T70 / T90 Titration Excellence - Analytical Balance, e.g. XP205 - Precision Balance, e.g. MS6002S - Rondo 20 sample changer
Accessories - 3 additional dosing units - 2 x 10 mL DV1010 burette, 2 x 20 ml DV1020 burette - PP Titration beakers ME-101974
- LabX pro titration software
Results
No. Comment / ID Start time Sample size and results
1/6 +25 mL H2O / 30.23g/500mL + 10 mL 3g/60mLNa2CO3 -- 22.07.2010 08:30:39 R1 = 279.72 g/L Free Caustic NaOH R2 = 83.60 g/L Free Carbonate CaCO3 R3 = 18.42 g/L Content Al(OH)3 (g/L) R4 = 304.71 mg/g Content Al(OH)3 (mg/g) R5 = 39.83 % Content Al2O3 (%) 2/6 +25 mL H2O / 30.23g/500mL + 10 mL 3g/60mLNa2CO3 -- 22.07.2010 08:47:48 R1 = 276.73 g/L Free Caustic NaOH R2 = 85.45 g/L Free Carbonate CaCO3 R3 = 18.19 g/L Content Al(OH)3 (g/L) R4 = 300.89 mg/g Content Al(OH)3 (mg/g) R5 = 39.33 % Content Al2O3 (%) 3/6 +25 mL H2O / 30.23g/500mL + 10 mL 3g/60mLNa2CO3 -- 22.07.2010 09:04:36 R1 = 275.96 g/L Free Caustic NaOH R2 = 82.50 g/L Free Carbonate CaCO3 R3 = 18.10 g/L Content Al(OH)3 (g/L) R4 = 299.43 mg/g Content Al(OH)3 (mg/g) R5 = 39.14 % Content Al2O3 (%) 4/6 +25 mKL HO / 30.23g/500mL + 10 mL 3g/60mLNa2CO3 -- 22.07.2010 09:21:20 R1 = 275.76 g/L Free Caustic NaOH R2 = 85.72 g/L Free Carbonate CaCO3 R3 = 18.18 g/L Content Al(OH)3 (g/L) R4 = 300.74 mg/g Content Al(OH)3 (mg/g) R5 = 39.31 % Content Al2O3 (%) 5/6 +25 mL H2O / 30.23g/500mL + 10 mL 3g/60mLNa2CO3 -- 22.07.2010 09:38:06 R1 = 274.60 g/L Free Caustic NaOH R2 = 84.16 g/L Free Carbonate CaCO3 R3 = 18.21 g/L Content Al(OH)3 (g/L) R4 = 301.19 mg/g Content Al(OH)3 (mg/g) R5 = 39.37 % Content Al2O3 (%) 6/6 +25 mL H2O / 30.23g/500mL + 10 mL 3g/60mLNa2CO3 -- 22.07.2010 09:54:50 R1 = 276.91 g/L Free Caustic NaOH R2 = 85.52 g/L Free Carbonate CaCO3 R3 = 18.38 g/L Content Al(OH)3 (g/L) R4 = 303.94 mg/g Content Al(OH)3 (mg/g) R5 = 39.73 % Content Al2O3 (%) Statistics Rx Name n Mean value Unit s srel [%] R1 Free Caustic NaOH 6 276.61 g/L 1.729829 0.625 R2 Free Carbonate CaCO3 6 84.49 g/L 1.292786 1.530 R3 Content Al(OH)3 (g/L) 6 18.25 g/L 0.125167 0.686 R4 Content Al(OH)3 (mg/g) 6 301.82 mg/g 2.048743 0.679 R5 Content Al2O3 (%) 6 39.45 % 0.267806 0.679
Titration curve (1st Titration: NaOH and carbonate)
Sample 1/6 22.07.2010 08:30
Table of measured values (1st Titration: NaOH and carbonate) Volume Increment Signal Change 1st derive. Time Temperature mL mL pH pH pH/mL s °C ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ 0.000 NaN 13.542 NaN NaN 0 25.0 17.143 17.143 13.295 -0.247 NaN 20 25.0 25.714 8.571 13.024 -0.271 NaN 57 25.0 30.000 4.286 12.842 -0.182 NaN 63 25.0 30.200 0.200 12.794 -0.048 NaN 82 25.0 30.400 0.200 12.781 -0.013 -0.06 85 25.0
... ... ... ... ... ... ... 39.011 0.088 11.242 -0.070 -0.86 220 25.0 39.151 0.140 11.114 -0.128 -0.92 224 25.0 EQP1 39.219895 11.049 NaN -0.93 NaN NaN 39.248 0.097 11.023 -0.091 -0.93 227 25.0 39.354 0.106 10.922 -0.101 -0.88 230 25.0 39.460 0.106 10.826 -0.096 -0.84 234 25.0 39.579 0.119 10.735 -0.091 -0.79 236 25.0 39.736 0.157 10.618 -0.117 -0.72 240 25.0 39.876 0.140 10.526 -0.092 -0.66 243 25.0 40.056 0.180 10.404 -0.122 -0.60 272 25.0 40.202 0.146 10.321 -0.083 -0.54 275 25.0 40.402 0.200 10.219 -0.102 -0.48 278 25.0 40.602 0.200 10.044 -0.081 -0.41 284 25.0 41.002 0.200 9.968 -0.076 -0.41 287 25.0 41.202 0.200 9.879 -0.089 -0.41 290 25.0 41.402 0.200 9.797 -0.082 -0.41 293 25.0 41.602 0.200 9.712 -0.085 -0.42 296 25.0 41.802 0.200 9.627 -0.085 -0.43 299 25.0 42.002 0.200 9.542 -0.085 -0.45 302 25.0 42.202 0.200 9.442 -0.100 -0.50 305 25.0 42.402 0.200 9.338 -0.104 -0.57 309 25.0 42.595 0.193 9.228 -0.110 -0.67 312 25.0 42.758 0.163 9.109 -0.119 -0.81 315 25.0 42.868 0.110 9.015 -0.094 -0.93 318 25.0 42.971 0.103 8.918 -0.097 -1.11 321 25.0 43.069 0.098 8.811 -0.107 -1.35 324 25.0 43.150 0.081 8.701 -0.110 -1.64 327 25.0 43.211 0.061 8.600 -0.101 -1.94 330 25.0 43.261 0.050 8.493 -0.107 -2.29 333 25.0 43.298 0.037 8.401 -0.092 -2.60 336 25.0 43.334 0.036 8.302 -0.099 -2.93 339 25.0 43.368 0.034 8.191 -0.111 -3.27 342 25.0 43.394 0.026 8.111 -0.080 -3.47 345 25.0 EQP2 43.404282 NaN 8.071 NaN -3.47 NaN NaN 43.429 0.035 7.975 -0.136 -3.43 348 25.0 43.450 0.021 7.895 -0.080 -3.22 352 25.0 43.477 0.027 7.813 -0.082 -2.91 356 25.0 43.520 0.043 7.691 -0.122 -2.54 360 25.0 43.559 0.039 7.606 -0.085 -2.25 365 25.0 43.620 0.061 7.484 -0.122 NaN 371 25.0 43.676 0.056 7.395 -0.089 NaN 376 25.0 43.756 0.080 7.284 -0.111 NaN 381 25.0 43.842 0.086 7.187 -0.097 NaN 387 25.0 43.952 0.110 7.085 -0.102 NaN 393 25.0
METTLER TOLEDO Page 3 of 7 Titration Application M466A-2010
Titration curve (2nd Titration: Aluminum)
Sample 1/6 22.07.2010 08:30
Table of measured values (2nd Titration: Aluminum) Volume Increment Signal Change 1st deriv. Time Temperature mL mL mV mV mV/mL s oC --------------------------------------------------------------------------------------------------------------------------------------------------------------------- 0.000 NaN -191.9 NaN NaN 0 25.0 0.005 0.005 -191.7 0.2 NaN 3 25.0 0.010 0.005 -191.6 0.1 NaN 6 25.0 0.022 0.012 -191.3 0.3 NaN 9 25.0 0.052 0.030 -190.4 0.9 NaN 12 25.0 0.127 0.075 -188.4 2.0 26.57 15 25.0 0.315 0.188 -183.7 4.7 24.46 19 25.0 0.515 0.200 -178.8 4.9 23.88 23 25.0 0.715 0.200 -174.2 4.6 23.24 26 25.0 0.915 0.200 -169.8 4.4 23.22 31 25.0 1.115 0.200 -164.8 5.0 23.99 35 25.0 1.315 0.200 -159.6 5.2 24.70 38 25.0 1.515 0.200 -155.2 4.4 26.05 42 25.0 1.715 0.200 -149.3 5.9 27.88 46 25.0 1.915 0.200 -143.2 6.1 30.89 50 25.0 2.115 0.200 -137.1 6.1 36.57 54 25.0 2.315 0.200 -128.8 8.3 45.60 58 25.0 2.503 0.188 -119.9 8.9 59.88 61 25.0 2.650 0.147 -110.6 9.3 78.62 65 25.0 2.746 0.096 -102.7 7.9 96.22 68 25.0 2.819 0.073 -96.1 6.6 111.74 72 25.0 2.900 0.081 -85.7 10.4 130.48 76 25.0 2.944 0.044 -80.1 5.6 144.01 79 25.0 EQP1 3.002191 NaN -70.0 NaN 158.53 NaN NaN 3.006 0.062 -69.3 10.8 158.46 83 25.0 3.040 0.034 -62.2 7.1 154.14 86 25.0 3.072 0.032 -57.5 4.7 139.57 90 25.0 3.150 0.078 -46.9 10.6 121.06 95 25.0 3.213 0.063 -40.0 6.9 107.18 100 25.0 3.305 0.092 -31.7 8.3 NaN 106 25.0 3.413 0.108 -23.8 7.9 NaN 111 25.0 3.546 0.133 -14.9 8.9 NaN 116 25.0 3.679 0.133 -7.8 7.1 NaN 121 25.0 3.862 0.183 0.7 8.5 NaN 126 25.0
METTLER TOLEDO Page 4 of 7 Titration Application M466A-2010
Comments
Principle:
• Bauxite contains approximately 30 – 54% alumina (Al2O3). The rest mainly consists of silica, iron oxides, and titanium dioxide.
• During the Bayer process bauxite is digested by washing with a hot solution of sodium hydroxide, NaOH, at 175°C. The alumina is first converted into aluminum hydroxide, Al(OH)3, which subsequently dissolves in the hydroxide solution according to the chemical equation:
Al2O3 + 2 OH- + 3 H2O → 2 [Al(OH)4]- The resulting, strong alkaline solution is called “Bayer liquor”.
Left: Bauxite powder Middle and right: Digested bauxite solution (Bayer liquor). Note that the digested solution is turbid due to the presence of precipitated iron componds (iron hydroxide).
Titration of Bayer liquor with hydrochloric acid:
• Addition of excess sodium gluconate (NaGluc):
Al(OH)4- + NaGluc → Al(OH)3Gluc- + NaOH
• Titration with 1 mol/L hydrochloric acid, HCl:
1st Equivalence point:
OH- + H3O+ → 2 H2O
CO32- + H+ → HCO3
-
2nd Equivalence point:
HCO3- + H3O+ → CO2 + 2 H2O
• Addition of excess potassium fluoride:
Al(OH)3Gluc- + 6KF → K3AlF6 + 3KOH + Gluc-
• The released KOH is titrated with 1 mol/L HCl:
OH- + H3O+ → 2 H2O
Digestion of bauxite:
Generally, a freshly prepared NaOH solution does not contain carbonate. Thus, only one equivalence point can be detected in the first titration with HCl. Carbonate is formed in alkaline solution due to intake of CO2 during a long exposition time to air. To reproduce two equivalence points, the synthetic Bayer liquor was spiked with 10 mL sodium carbonate solution (approx. 3 g Na2CO3/60 mL).
METTLER TOLEDO Page 5 of 7 Titration Application M466A-2010
METTLER TOLEDO Page 6 of 7 Titration Application M466A-2010
Method
001 Title
Type General titration
Compatible with T70 / T90
ID m466
Title Aluminum content in bauxite
Author Administrator
Date/Time 23.07.2010 16:23:20
Modified at 23.07.2010 16:23:20
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 --
Entry type Fixed volume
Volume [ml] 5.0
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Rondo/Tower A)
Type Rondo/Tower A
Titration stand Rondo60/1A
Lid handling No
004 Dispense (normal) [1]
Titrant Na-gluconate
Concentraition [mol/L] 25
Volume [mL] 10
Dosing rate [ml/min] 60
Condition No
005 Stir
Speed [%] 30
Duration [s] 120
Condition No
006 Titration (EQP) [1]
Titrant
Titrant HCl
Concentration [mol/L] 1
Sensor
Type pH
Sensor DG115-SC
Unit pH
Temperature acquisition
Temperature acquisition No
Stir
Speed [%] 30
Predispense
Mode Volume
Volume [ml] 30
Waiting time [s] 15
Control
Control User
Titrant addition Dynamic
dE (set value)[mV] 6
dV (min)[ml] 0.002
dV (max)[ml] 0.2
Mode Equilibrium controlled
dE[mV] 0.5
dt[s] 1
t (min)[s] 3.0
t (max)[s] 30.0
Evaluation and recognition
Procedure Standard
Threshold[pH/ml] 0.5
Tendency Negative
Ranges 0
Add. EQP criteria No
Termination
At Vmax [ml] 60
At potential Yes
Potential [pH] 6
Termination tendency Negative
At slope No
After number of
recognized EQPs Yes
Number of EQPs 2
Combined termination
criteria No
Accompanying stating No
Condition No
007 Dispense (normal) [2]
Titrant KF
Concentration [mol/L] 30
Volume [mL] 10
Dosing rate [ml/min] 60
Condition No
008 Stir
Speed [%] 30
Duration [s] 180
Condition No
009 Titration (EQP) [2]
Titrant
Titrant HCl
Concentration [mol/L] 1
Sensor
Type pH
Sensor DG115-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed[&] 30
Predispense
Mode None
Waiting time [s] 0
Control
Control User
Titrant addition Dynamic
dE (set value)[mV] 8.0
dV (min)[ml] 0.005
dV (max)[ml] 0.2
Mode Equilibrium controlled
dE[mV] 0.5
dt[s] 1
t (min)[s] 3.0
t (max)[s] 30.0
Evaluation and recognition
Procedure Standard
Threshold[mV/ml] 5
Tendency Positive
Ranges 0
Add. EQP criteria Steepest jump
Steepest jumps 1
Termination
At Vmax[ml] 5
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating No
Condition No
010 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle[mL] 10
Position Current position
Drain No
Condition No
011 Conditioning
Type Fix
Interval 1
Position Conditioning beaker
Time [s] 60
Speed [%] 30
Condition No
012 Calculation R1
Result Free Caustic NaOH
Result unit g/L
Formula R1=(Q-Q2)*C/m
Constant C= M/z
M M[Sodium hydroxide]
z z[Sodium hydroxide]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
013 Calculation R2
Result Free Carbonate CaCO3
Result unit g/L
METTLER TOLEDO Page 7 of 7 Titration Application M466A-2010
Formula R2=Q2*C/m
Constant C= M/z
M M[Calcium carbonate]
z z[Calcium carbonate]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
014 Calculation R3
Result Content Al(OH)3 (g/L)
Result unit g/L
Formula R3=(Q[2]+QEX)*C/m
Constant C= M/z
M M[Aluminum trihydroxide]
z z[Aluminum trihydroxide]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
015 Calculation R4
Result Content Al(OH)3 (mg/g)
Result unit mg/g
Formula R4=((Q[2]+QEX)*C/30.23)*100
Constant C= M/z
M M[Aluminum trihydroxide]
z z[Aluminum trihydroxide]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
016 Calculation R5
Result Content AL2O3 (%)
Result unit %
Formula R5=(R4/10)*C
Constant C= 1.30717
M M[None]
z z[None]
Decimal places 2
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
017 End of sample
018 Park
Titration stand Rondo60/1A
Position Conditioning beaker
Condition No
Calculation R4: 30.23 = sample size of bauxite powder 100 = dilution factor (5 mL -> 500 mL) Calculation R5: 1.30717 = M(Al2O3)/M(Al(OH)3) = 101.96/78.00
METTLER TOLEDO Application M222-2010
Determination of Boric Acid in Acidic HCl/HF Solutions Boric acid is determined by titration with sodium hydroxide after addition of mannitol. The titration is monitored by a combined pH glass electrode.
Preparation and Procedures - 5 mL acidic bath is diluted with 50 mL deionized
water.
- The sample is titrated with sodium hydroxide to pH 7 (= 0 mV).
- This gives the total acid content (HCl, HF) present in the sample.
- 20 mL mannitol solution is automatically added to the sample beaker by means of an additional burette.
- The sample solution is stirred for 20 s or during a longer time to allow for a complexation reaction between mannitol and boric acid.
- The complexation reaction leads to a release of hydrogen ions.
- These ions can be titrated with 0.1 mol/L NaOH.
Remarks
- The method was developed on a DL70 titrator and has been adapted for T50/T70/T90 Titration Excellence.
- Boric acid is a weak monobasic acid in aqueous solutions. Thus, it cannot be directly titrated using a strong base.
- Mannitol, C6H8(OH)6 , forms a stable 1:1 complex with boric acid:
B(OH)3 + M → B(OH)2O-M- + H+
- The released hydrogen ions can be titrated with sodium hydroxide solution.
In general:
- The addition of mannitol solution allows to avoid volatilization of boron in sample solutions, and to increase the dissociation strength to achieve optimum titration conditions (For more detailed information, see Literature under “Comments”).
Sample Acidic bath, 5 mL
Compound - Boric acid, B(OH)3 M = 61.83, z = 1
- Hydrochloric acid, HCl - Hydrofluoric acid, HF
Chemicals - 50 mL deionized water, - 20 mL mannitol solution,
C6H8(OH)6 , c(C6H8(OH)6) = 200 g/L
Titrant Sodium hydroxide, NaOH, c(NaOH) = 0.1 mol/L
Standard Potassium hydrogen phthalate, KHP, see e.g. M002
Indication DGi112-SC or DGi114-SC combined pH glass electrode with movable sleeve
Chemistry Simplified reaction scheme:
B(OH)3 + M → B(OH)2O-M- + H+
H3O+ + NaOH → 2 H2O + Na+
where M = C6H8(OH)6
Calculation Content boric acid (g/L):
R = Q*C/m
C = M/z
Waste disposal
Neutralization with hydrochloric acid before final disposal
Author, Version
Dieter Rehwald, MT-Germany,1989 Rev. February 2010 / C. De Caro
METTLER TOLEDO Page 1 of 5 Titration Application M222-2010
Instruments - DL70 Titrator - Balance, e.g. XS205
Other titrators: This method can also be run with the T50/T70/T90 Titration Excellence, and with the DL55, DL58, DL70ES, and DL77 instruments. Minor changes in the methods are required.
Accessories - 2 x 10 mL DV1010 burettes - Additional dosing unit (Tx) ME-51109030, or burette drive (DL5x, DL7x) - PP titration beaker ME-101974 - Printer
Results METTLER DL70 Titrator A001 Borsäure Measured 14-Nov-1989 12:44 14-Nov-1989 12:28 Titrator SW Version 1.2 User **** RESULTS No ID1 Volume Results 1/1 4711 5.0 mL 5.179 mL ml HCl/HF 9.245 mL ml Brsaeure 11.43 g/L Content
Titration curve
METTLER TOLEDO Page 2 of 5 Titration Application M222-2010
METTLER TOLEDO Page 3 of 5 Titration Application M222-2010
Table of measured values Not available
Comments
• Boric acid is used in various market segments and for the most different applications such as e.g. antiseptic, flame retardant, and in nuclear power plants to control the rate of fission. In electroplating and semiconductor industry it is used among other purposes for e.g. surface treatment and metal processing (e.g. nickel baths, boron metal alloys).
• The acid dissociation constant pKa of boric acid B(OH)3 is 9.14 at 25°C, thus it is a rather weak acid.
• Boric acid does not dissociate in aqueous solution, but is acidic due to its interaction with water molecules, forming tetrahydroxyborate ions:
B(OH)3 + H2O → B(OH)4- + H+ Ka = 5.8x10−10 mol/l; pKa = 9.24
However, the dissociation is not so strong, and therefore the released hydrogen ions can not be directly titrated with a strong base.
Literature:
- METTLER TOLEDO Application Brochure No. 1, “18 Customer Methods””, ME-724492, 1992.
- T. Ishikawa, E. Nakamura, “Formation of Boron-mannitol Complex in the Hydrofluoric Acid Solution and a Possibility of the Use of Acids in the Separation of Boron from the Natural rock Samples”, Proc. Japan Acad. 66 No.5 (Ser. B), p. 91, 1990.
- P. M. Williams and P. M. Strack, “Complexes of Boric Acid with Organic Cis-Diols in Seawater”, Limnology and Oceanography, Vol. 11, No. 3, pp. 401-404, 1966.
- P. A. Webster, “Determination of Boric Oxide in Glass by Direct Titration”, Journal of the American Ceramic Society, Volume 34 Issue 10, pp 305-309, 1951.
- Max Hollander, William Rieman, “Titration of Boric Acid in Presence of Mannitol”, Ind. Eng. Chem. Anal. Ed. 17 (9), pp 602–603, 1945.
METTLER TOLEDO Page 4 of 5 Titration Application M222-2010
Method DL70 Titrators:
Title
Method ID ........................... A001
Title ............................... Borsäure
Date/time ........................... 14-Nov-1989 12:28
Sample
Number samples ...................... 1
Titration stand ..................... Stand 1
Entry type .......................... Volume U
Lower limit [mL].................. 1.0
Upper limit [mL].................. 10.0
ID1 ................................. 4711
Molar mass M ........................ 61.83
Equivalent number z ................ 1
Stir
Speed [%] ........................... 50
Time [s] ............................ 10
Titration
Titrant ............................. NaOH
Concentration [mol/L] ............... 0.1
Sensor .............................. DG112-SC
Unit of meas. ...................... mV
Titration mode ...................... EP
Predispensing 1................... to volume
Volume [mL] .................... 1.0
Titrant addition .................... Dynamic
dE(set) [mV] ................... 8.0
dV(min) [mL] ................... 0.02
dV(max) [mL] ................... 0.1
dE [mV] ........................ 0.5
dt [s] ......................... 0.5
t(min) [s] ..................... 2.0
t(max) [s] ..................... 20.0
Endpunktart ......................... EPA
Potential [mV,pH,…] ............ 0.0
Tendency ............................ Negative
Maximum volume [mL] ................. 10.0
Calculation
Result name ......................... mL HCl/HF
Formula ............................ R=VEQ
Constant ............................ C=1
Result unit ......................... mL
Decimal places ...................... 3
Record
All results ......................... Yes
Table of measured values ............ Yes
E – V curve ......................... Yes
Dispense
Titrant ............................. Mannit
Concentration [mol/L] ............... 0.0
Volume [mL] ......................... 20.0
Stir
Speed [%] ........................... 50
Time [s] ............................ 20
Titration
Titrant ............................. NaOH
Concentration [mol/L] ............... 0.1
Sensor .............................. DG112-SC
Unit of meas. ...................... mV
Titration mode ...................... EQP
Predispensing 1................... to volume
Volume [mL] .................... 1.0
Titrant addition .................... DYN
dE(set) [mV] ................... 8.0
Limits dV ...................... Absolute
dV(min) [mL]................. 0.02
dV(max) [mL]................. 0.2
Measure mode ....................... EQU
dE [mV] ........................ 1.0
dt [s] ......................... 1.0
t(min) [s] ..................... 3.0
t(max) [s] ..................... 30.0
Threshold ........................... 20.0
Maximum volume [mL] ................. 10.0
Evaluation procedure ................ Standard
Calculation
Result name ......................... mL Brsaeure
Formula ............................ R2=VEQ[2]+VEX[1]
Constant ............................ C2=1
Result unit ......................... mL
Decimal places ...................... 3
Calculation
Result name ......................... Content
Formula ............................ R3=(Q[2]+QEX[1])*C3/U
Constant ............................ C3=M/z
Result unit ......................... g/L
Decimal places ...................... 2
Record
All results ..........................Yes
Table of measured values .............Yes
E – V curve ..........................Yes
--------------------------------------------------------------
Titration Excellence:
001 Title
Type General titration
Compatible with T50/T70/T90
ID m222
Title Boric acid
Author Mettler Toledo
Date/Time 01.02.2010 08:00:00
Modified at 01.02.2010 08:00:10
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Acidic solution
Entry type Volume
Lower limit 1.0 mL
Upper limit 10.0
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Before
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Stir
Speed 50%
Duration 10 s
Condition No
005 Titration (EP) [1]
Titrant
Titrant NaOH
Concentration 0.1 mol/L
Sensor
Type pH
Sensor DG115-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 1.0
Waiting time 10 s
Control
End point type Absolute
Tendency Negative
End point value 0.0 mV
Control band 100.0 mV
Dosing rate(max) 10 mL/min
Dosing rate(max) 10 µL/min
Termination
At EP Yes
Termination delay 10 s
At Vmax 10.0 mL
Max. time infinity
006 Calculation R1
Result Consumption HCl/HF
Result unit mL
Formula R1 = VEQ[1]
Constant C= 1
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics No
007 Record
Summary No
Results Per sample
Raw results No
Table of meas. values Yes
METTLER TOLEDO Page 5 of 5 Titration Application M222-2010
Sample data No
Resource data No
E - V Yes
dE/dV - V No
log dE/dV - V No
d2E/dV2 - V No
BETA – V No
E - t No
V - t No
dV/dt - t No
T – t No
E – V & dE/dV – V No
V – t & dV/dt – t No
Method No
Series data No
Condition No
008 Dispense (normal) [1]
Titrant Mannitol
Concentration 1
Volume 20.0 mL
Dosing rate 60.0 mL/min
Condition No
009 Stir
Speed 50%
Duration 20 s
Condition No
010 Titration (EQP) [2]
Titrant
Titrant NaOH
Concentration 0.1 mol/L
Sensor
Type pH
Sensor DG115-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode Volume
Volume 1.0
Waiting time 10 s
Control
Control User
Titrant addition Dynamic
dE(set value) 8.0 mV
dV(min) 0.02 mL
dV(max) 0.2 mL
Mode Equilibrium controlled
dE 1.0 mV
dt 1 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 20
Tendency Negative
Ranges 0
Add. EQP criteria No
Termination
At Vmax 20.0 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
011 Calculation R2
Result Consumption boric acid
Result unit mL
Formula R2 = VEQ[2]+VEX[1]
Constant C= 1
M M[None]
z z[None]
Decimal places 3
Result limits No
Record statistics No
012 Calculation R3
Result Boric acid content
Result unit g/L
Formula R3 = (Q[2]+QEX[1])*C/m
Constant C= M/z
M M[B(OH)3]
z z[B(OH)3]
Decimal places 2
Result limits No
Record statistics Yes
013 Record
Summary No
Results Per sample
Raw results No
Table of meas. values Yes
Sample data No
Resource data No
E - V Yes
dE/dV - V No
log dE/dV - V No
d2E/dV2 - V No
BETA – V No
E - t No
V - t No
dV/dt - t No
T – t No
E – V & dE/dV – V No
V – t & dV/dt – t No
Method No
Series data No
Condition No
014 End of sample
METTLER TOLEDO Application M467-2010
Titanium Content in Mining Solutions Determination of titanium content in titanium ore digestion and purification solution.
Preparation and Procedures
CAUTION: Work with a lab coat, and wear gloves and safety goggles.
- Depending on the expected concentration of Ti3+ in the sample solution, the amount of sample is chosen in such a way that the final amount of Ti3+ in the titration vessel is ~ 0.5 mmol. This leads to a titrant consumption of ~ 5 mL, which is approximately half the burette volume.
- To the sample solution 40 mL deionised water and ~ 10 mL concentrated sulfuric acid are added to make the sample solution acidic enough for the redox reaction between iron and titanium to take place.
Remarks
- The parameters have been optimized for this specific sample. It may be necessary to adapt the method to your sample.
- Since Ti3+ is a very unstable species, the sample solution should always be prepared freshly.
- Also make sure to add the titanium solution to the titration beaker only directly before the titration itself. Otherwise loss of titanium can be observed within one sample series because of oxidation by air. The use of an inert gas such as nitrogen could be recommended.
- Please take care when handling the concentrated sulfuric acid as this will cause severe burns when in contact with skin.
Sample Digestion solution from titanium ore (e.g. TiO2) ~ 5 mL
Compound Titanium, Ti3+, M = 47.867 g/mol, z = 1
Chemicals 40 mL deionized water 10 mL concentrated H2SO4
Titrant Ferric ammonium sulfate, NH4Fe(SO4)2 (Fe(III)AS) c(NH4Fe(SO4)2) = 0.1 M
Standard Ascorbic acid, C6H8O6
Indication DMi140-SC
Chemistry Fe3+ + Ti3+ → Fe2+ + Ti4+
Calculation Ti-Content (g/L): R1 = Q*C/m C = M/z Content (mol/L): R2 = Q*C/m C = 1/z
Waste disposal
After neutralization of the acid dispose the sample solution as heavy metals.
Author, Version
Melanie Nijman, MSG Anachem, June 2010
METTLER TOLEDO Page 1 of 4 Titration Application M467-2010
Instruments - T50/T70/T90 Titration Excellence - Balance, e.g. XS205 - Rondo 20 sample changer
Accessories - 1 x 10 mL DV1010 burette - PP Titration beakers ME-101974 - LabX pro titration software
Results
Samples 1/6 Titanium solution 5.0 mL 2/6 Titanium solution 5.0 mL 3/6 Titanium solution 5.0 mL 4/6 Titanium solution 5.0 mL 5/6 Titanium solution 5.0 mL 6/6 Titanium solution 5.0 mL Results Comment / ID Rx Result Unit Name
1/6 Titanium solution R1 = 4.1367 g/L Content R2 = 0.08642 mol/L Content 2/6 Titanium solution R1 = 4.1726 g/L Content R2 = 0.08717 mol/L Content 3/6 Titanium solution R1 = 4.1402 g/L Content R2 = 0.08649 mol/L Content 4/6 Titanium solution R1 = 4.1297 g/L Content R2 = 0.08628 mol/L Content 5/6 Titanium solution R1 = 4.1821 g/L Content R2 = 0.08737 mol/L Content 6/6 Titanium solution R1 = 4.1518 g/L Content R2 = 0.08674 mol/L Content Statistics
Rx Name n Mean value Unit s srel [%] R1 Content 6 4.1522 g/L 0.0210 0.505 R2 Content 6 0.08675 mol/L 0.00044 0.505
Titration curve
METTLER TOLEDO Page 2 of 4 Titration Application M467-2010
METTLER TOLEDO Page 3 of 4 Titration Application M467-2010
Table of measured values
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL s 0.0000 NaN 127.3 NaN NaN 0 0.0200 0.0200 15.0 -112.3 NaN 36 0.0400 0.0200 -55.7 -70.7 NaN 66 0.0600 0.0200 -67.9 -12.2 NaN 86 0.1100 0.0500 -68.1 -0.2 NaN 89 0.2350 0.1250 -67.0 1.1 -164.84 92 0.5475 0.3125 -62.5 4.5 -17.93 96 1.0475 0.5000 -55.6 6.9 13.16 100 1.5475 0.5000 -49.7 5.9 15.36 104 2.0475 0.5000 -43.9 5.8 13.92 108 2.5475 0.5000 -35.7 8.2 14.57 113 3.0300 0.4825 -21.8 13.9 24.96 117 3.1870 0.1570 -31.5 -9.7 32.84 136 3.2480 0.0610 -29.6 1.9 35.89 138 3.4005 0.1525 -20.5 9.1 47.54 142 3.4695 0.0690 -18.9 1.6 53.25 157 3.6420 0.1725 -2.0 16.9 99.88 162 3.6620 0.0200 -2.0 0.0 98.15 168 3.7120 0.0500 1.2 3.2 116.80 180 3.7440 0.0320 4.5 3.3 122.92 188 3.7900 0.0460 10.4 5.9 148.23 196 3.8415 0.0515 20.3 9.9 220.52 210 3.8695 0.0280 27.0 6.7 259.63 221 3.8960 0.0265 34.4 7.4 296.47 232 3.9205 0.0245 41.4 7.0 355.89 244 3.9475 0.0270 51.6 10.2 457.57 257 3.9675 0.0200 61.2 9.6 597.72 260 3.9875 0.0200 70.0 8.8 705.32 269 4.0075 0.0200 91.5 21.5 765.55 272 4.0275 0.0200 111.4 19.9 849.06 275 4.0475 0.0200 133.1 21.7 932.52 278 4.0675 0.0200 140.1 7.0 1200.09 291 4.1175 0.0500 206.2 66.1 1654.10 304 4.1375 0.0200 254.7 48.5 1851.92 308 EQP1 4.1388 NaN 257.2 NaN 1915.87 NaN 4.1575 0.0200 292.5 37.8 1856.88 313 4.1775 0.0200 344.2 51.7 1544.28 343 4.1975 0.0200 365.0 20.8 1098.89 351 4.2175 0.0200 376.4 11.4 797.07 354 4.2430 0.0255 387.0 10.6 593.63 357 4.2695 0.0265 394.7 7.7 NaN 360 4.3085 0.0390 402.4 7.7 NaN 363 4.3685 0.0600 410.9 8.5 NaN 366 4.4470 0.0785 419.7 8.8 NaN 370 4.5365 0.0895 426.5 6.8 NaN 373
Comments
--
METTLER TOLEDO Page 4 of 4 Titration Application M467-2010
Method 001 Title
Type General titration
Compatible with T50 / T70 / T90
ID MNxxxE
Title Titanium content
Author Administrator
Date/Time 01/06/2010 18:11:34
Modified at 02/06/2010 08:45:39
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Titanium Solution
Entry type Fixed volume
Volume [mL] 5.0
Density [g/mL] 1.0
Correction factor 1.0
Temperature [°C] 25.0°C
003 Titration stand (Rondo/TowerA)
Type Rondo/Tower A
Titration stand Rondo60/1A
Lid handling No
004 Stir
Speed [%] 30
Duration [s] 10
Condition No
005 Titration (EQP) [1]
Titrant
Titrant F(III)AS
Concentration [mol/L] 0.1
Sensor
Type mV
Sensor DM140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed [%] 30
Predispense
Mode None
Wait time [s] 5
Control
Control User
Titrant addition Dynamic
dE (set value) [mV] 8.0
dV (min) [mL] 0.02
dV (max) [mL] 0.2
Mode Equilibrium controlled
dE [mV] 0.5
dt [s] 2
t (min) [s] 3
t (max) [s] 10
Evaluation and recognition
Procedure Standard
Threshold [mV/mL] 1500
Tendency None
Ranges 0
Add. EQP criteria No
Termination
At Vmax [mL] 10.0
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating No
Condition No
007 Calculation R1
Result Content
Result unit g/L
Formula R1=Q*C/m
Constant C= M/z
M M[Titanium]
z z[Titanium]
Decimal places 4
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
008 Calculation R2
Result Content
Result unit mol/L
Formula R2=Q*C/m
Constant C= 1/z
M M[Titanium]
z z[Titanium]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical func. No
Send to buffer No
Condition No
009 Rinse
Auxiliary reagent Water
Rinse cycles 1
Vol. per cycle[mL] 15
Position Current position
Drain No
Condition No
010 Conditioning
Type Fix
Interval 1
Position Conditioning beaker
Time [s] 10
Speed [%] 30
Condition No
011 End of sample
METTLER TOLEDO Application M458-2010 Determination of Cobalt Content in Alloys
The cobalt content in alloys is determined by redox titration in strong acid solution with potassium hexacyanoferrate K3Fe(CN)6 as a titrant. The potential change is monitored by a combined platinum ring electrode.
Preparation and Procedures CAUTION: Cyanide is toxic!
A too low pH value leads to the formation of HCN gas which is toxic. Thus, work in a fume hood, use safety goggles and wear gloves. Sample dissolution: - 0.15 g metallic alloy is placed in a suitable
container for dissolution e.g. a platin crucible. - 5 mL concentrated nitric acid is added,
together with 2-3 mL hydrofluoric acid. - The solution is heated until alloy is dissolved. - After cooling down to room temperature, 10-15
mL deionized water is added. - The sample solution in poured into a
polypropylene titration beaker. Cobalt is now present as Co(II)
Titration: - 10 mL 50% ammonium citrate is added to the
sample - 20 mL ammonium hydroxide solution is added
to the sample. - Add 10-20 mL deionized water. - Start titration.
Remarks
- The method parameters have been developed and optimized for this application. It may be necessary to adapt the method to your sample.
- Clean the electrode thoroughly after each sample. If necessary, clean the metal ring of the electrode with a paper tissue.
Literature:
- ISO 9389:1989 (E), “Nickel alloys- Determination of cobalt content – Potentiometric titration with potassium hexacyanoferrate(III)”, www.iso.org .
- H. Poppe, G. Den Boef, “Photometric titration of cobalt with hexacyanoferrate(III)”, Talanta, Vol. 12, Issue 6, 1965, pp 625-637.
- E. Norkus, “Potentiometric titration of Co(II) in presence of Co(III)”, Talanta, Vol. 47 (1998), pp 1297-1301.
Sample Metal alloy, 0.15 g 6-13% Co content
Compound Cobalt, Co M = 58.933; z = 1
Chemicals 85% Nitric acid, HNO3
48% Hydrofluoric acid, HF
50% Ammonium citrate, (NH4)3C6H5O7
30% Ammonium hydroxide, NH4OH
Deionized water
Titrant Potassium hexacyanoferrate, K3 Fe(CN)6, c(KFe(CN)6) = 0.017 mol/L
Standard Cobalt chloride, CoCl2
Indication DMi140-SC combined redox electrode
Chemistry Co(NH3)62+ + Fe(CN)6
3- → Co(NH3)6
3+ + Fe(CN)64-
Simplified: Co2+ + Fe 3+ → Co3+ + Fe2+
Calculation Content (DL5x) • R1 = Q*C/m • C = M/(10*z)
Waste disposal
Cyanide solutions. CAUTION: Cyanide is toxic!
Author, Version
Lee Hyun Jung, MT-Korea, Dec 2003 Revised January 2010 / C. De Caro
METTLER TOLEDO Page 1 of 5 Titration Application M458-2010
METTLER TOLEDO Page 2 of 5 Titration Application M458-2010
Instruments - DL50 Graphix Titrator - AT261 Balance This method can also be run with the G20 and T50/70/90 Titration Excellence (minor
adaptations in their method), and with the DL53/DL55/DL58, and DL67/70ES/77 instruments.
Accessories - 1 x 10 mL DV1010 burette - Titration beaker ME-101974 - Printer
Results Alloy Theoretical Results Std. srel Comments Co-content deviation % % % % G10E 6.0 5.964 Ammonium citrate: 7.5 mL 5.952 Ammonium hydroxide: 17.5 mL 5.956 5.973 Average: 5.961 0.009287 0.156 KPM25P 10.2 9.888 Ammonium citrate: 7.5 mL 10.091 Ammonium hydroxide: 17.5 mL 10.018 9.972 10.012 Average: 9.996 0.07417 0.742 CN20 7.8 7.375 Ammonium citrate: 7.5 mL 7.086 Ammonium hydroxide: 17.5 mL 6.869 6.600 6.329 Average: 6.852 0.407924 5.954 FA1 13.0 12.821 Ammonium citrate: 7.5 mL 12.576 Ammonium hydroxide: 17.5 mL 12.541 12.548 12.316 Average: 12.560 0.179177 1.426 12.814 Ammonium citrate: 10 mL 12.807 Ammonium hydroxide: 20 mL 12.844 12.845 Average: 12.828 0.019841 0.155
Titration curve
KPM25P sample 1/5
Table of measured values
Volume Increment Signal Change 1st deriv. Time mL mL mV mV mV/mL min:s
ET1 0 -125.3 0:03 0.02 0.02 -125.1 0.2 9.7 0:06 0.04 0.02 -125 0.1 6.5 0:09 0.08 0.04 -125 0 0 0:12 … … … … … … … … … … … … 13.52 0.2 -58.5 4.3 21.6 5:01 13.72 0.2 -53.1 5.4 26.8 5:06 13.92 0.2 -47 6.1 30.4 5:12 14.12 0.2 -38.9 8.1 40.7 5:19 14.276 0.156 -30.7 8.2 52.6 5:26 14.4 0.124 -22 8.7 69.8 5:34 14.491 0.091 -14.2 7.9 86.6 5:42 14.568 0.077 -6 8.1 105.7 5:51 14.632 0.064 2.1 8.1 126.2 5:59 14.686 0.054 10.3 8.2 152 6:09 14.731 0.045 17.8 7.5 166.6 6:18 14.775 0.044 26.1 8.3 189.5 6:25
EQP1 14.812 0.037 34.3 8.2 221.8 6:34 14.843 0.031 41.1 6.8 218.9 6:43 14.88 0.037 49.2 8.1 218.3 6:51
KPM25P sample 1/5
METTLER TOLEDO Page 3 of 5 Titration Application M458-2010
METTLER TOLEDO Page 4 of 5 Titration Application M458-2010
Comments
Redox potential of cobalt (acidic solution) Co2+ + 2 e- = Co E = - 0.277 V Co3+ + e- = Co2+ E = + 1.808 V
Co2+ ion is stable in acidic solution.
Additional titration methods for the determination of cobalt
1. Redox titration of Co(II): Oxidation of Co(II) to Co(III) with a known excess of sodium chromate (Na2CrO4) and back titration with iron(II) ammonium sulfate, (NH4) 2FeSO4. Indication: DMi140-SC (combined platinum ring electrode) Reagents: - Sodium chromate (Na2CrO4), 0.033 mol/L - Iron(II) ammonium sulfate (NH4) 2FeSO4 , 0.1 mol/L - Ethylenediamine C2H4(NH2)2 , 0.1 mol/L - Sulfuric acid 50%, H2SO4 Procedure: Add to sample 10 mL 0.1 mol/L ethylenediamine, 4 mL 0.033 mol/L sodium chromate, and 5 mL 50% sulfuric acid. Titrate with 0.1 mol/L (NH4) 2FeSO4 (Determ. limits: 25 mg Co per sample).
2. Precipitation titration of Co(II) Precipitate Co(II) with an excess of cyanide solution and back titrate the cyanide excess with silver nitrate. Indication: DMi141-SC (combined silver ring electrode) Reaction: - Precipitation of Co(II) with an excess of cyanide: Co2+ + 5 CN- → [Co (CN)5]3- - Back titration of cyanide excess (two-step titration): Ag+ + 2 CN- → [Ag (CN)2]- [Ag (CN)2]- + Ag+ → 2 AgCN The titration curve shows two inflection points corresponding to the two steps of titration reaction. A soluble complex Ag(CN)2
- is first formed by the reaction between silver and cyanide ion:
Ag+ + 2 CN- → [Ag (CN)2]-
As long as free cyanide is still present, the solution remains clear. First excess of silver ions causes formation of a white precipitate indicating the equivalence point:
Ag+ + [Ag(CN)2]-→ Ag[Ag(CN)2]
1 mole Ag-ions : 2 moles CN-ions. A factor 2 has to be included in the calculation (see M196). Procedure: Dilute the sample in 50 mL water and add 20 mL 0.1 mol/L potassium cyanide KCN. Back titrate with 0.1 mol/L silver nitrate AgNO3 to the second EQP. 3. Complexometric titration of Co(III/II)
Direct titration of cobalt Co3+ is performed in ammonia-containing solution with EDTA and murexide as indicator. The endpoint is given by a sharp color change from yellow to red/violet. Indication: Photometric sensor, e.g. DP5 Phototrode™ at 520 nm. Procedure: The pH of the acidic cobalt solution (max. 25 mg/100 mL sample) is adjusted to approximately pH 6. Subsequently, murexide is added to the sample beaker, whereby an orange color is appearing. Ammonia solution is added until the color has changed to yellow. The solution has to be slightly basic (e.g. pH 8). At that point, the sample solution is titrated with EDTA. During titration, the solution becomes acidic due to release of hydrogen ions H+ from EDTA, and the color is vanishing back from yellow to orange. To avoid it, it is necessary to add some drops of ammonia during titration to get back the yellow color. Important: do not add too much ammonia since amine complexes of cobalt are formed.
METTLER TOLEDO Page 5 of 5 Titration Application M458-2010
Method DL5x Titrator
Method 1 Cobalt II
Version 03-Dec-2003 8:35
Title
Method ID .......................... 1
Title .............................. Cobalt II
Date/time .......................... 03-Dec-2003 8:35
Sample
Sample ID ..........................
Entry type ......................... Weight
Lower limit [g] ................ 0.0
Upper limit [g] ................ 2.0
Molar mass M ....................... 58.933
Equivalent number z ................ 1
Titration stand .................... Stand 1
Temperature sensor ................. Manual
Stir
Speed [%] .......................... 40
Time [s] ........................... 20
EQP titration
Titrant/Sensor
Titrant ........................ K3Fe(CN)6
Concentration [mol/L] .......... 0.017
Sensor ......................... DM140-SC
Unit of meas. .................. mV
Predispensing ...................... No
Titrant addition ................... Dynamic
dE(set) ........................ 8.0
dV(min) [mL] ................... 0.02
dV(max) [mL] ................... 0.2
Measure mode ....................... Equilibrium controlled
dE [mV] ........................ 0.5
dt [s] ......................... 1.0
t(min) [s] ..................... 3.0
t(max) [s] ..................... 30.0
Recognition
Threshold ...................... 30.0
Steepest jump only ............. No
Range .......................... No
Tendency ....................... Positive
Termination
at maximum volume [mL] ......... 20.0
at potential ................... No
at slope ....................... No
after number EQPs .............. Yes
n = ...................... 1
comb. termination criteria ..... No
Evaluation
Procedure ...................... Standard
Potential 1 ................... No
Potential 2 ................... No
Stop for reevaluation ......... No
Calculation
Formula ........................... R1=Q*C/m
Constant ........................... C1=M/(10*z)
Decimal places ..................... 3
Result unit ........................ %
Result name ........................ Co content
Statistics ........................ Yes
Calculation
Formula ........................... R2=VEQ
Constant ...........................
Decimal places ..................... 3
Result unit ........................ mL
Result name ........................ Consumption
Statistics ........................ No
Report
Output unit ....................... Printer
Results ............................ Yes
All results ........................ Yes
Raw results ........................ No
Table of measured values ........... Yes
Sample data ........................ No
E - V curve ........................ Yes
dE/dV – V curve .................... Yes
d2E/dV2 – V curve ................... No
log dE/dV – V curve... ............. No
E – t curve ........................ No
V – t curve ........................ No
dV/dt - t curve ................... No
Titration Excellence
001 Title
Type General titration
Compatible with T50 / T70 / T90
ID 1
Title Cobalt II
Author METTLER TOLEDO
Date/Time 01.03.2010 15:00:00
Modified --
Modified by --
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 -- 1
Entry type Weight
Lower limit 0.0 g
Upper limit 2.0 g
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Stir
Speed 40%
Duration 20 s
005 Titration (EQP) [1]
Titrant
Titrant K3Fe(CN)6
Concentration 0.017 mol/L
Sensor
Type mV
Sensor DM140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 40%
Predispense
Mode None
Wait time 0 s
Control
Control User
Titrant addition Dynamic
dE(set) 8.0
dV(min) 0.02 mL
dV(max) 0.2 mL
Meas. val. acquisition Equilibrium controlled
dE 0.5 mV
dt 1.0 s
t(min) 3.0 s
t(max) 30.0 s
Evaluation and recognition
Procedure Standard
Threshold 30 mV/mL
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 20.0 mL
At potential No
At slope No
After number of
recognized EQPs No
Combined termination
criteria No
006 Calculation R1
Result Co content
Result unit %
Formula R=Q*C/m
Constant C=M/(10*z)
M M[Co]
z z[Co]
Decimal places 3
...
007 Calculation R2
Result Consumption
Result unit mL
Formula R2=VEQ
Constant C=1
M M[None]
z z[None]
Decimal places 3
...
008 Record
. . . .
009 End of sample
METTLER TOLEDO Application M292-2010
Determination of Uranium according to Modified Davies-Gray Method Uranium is determined by indirect titration using potassium dichromate according to the modified method of Davies and Gray. This application has been developed based on standard ASTM C1267-06, but it does not replace the standard used.
Preparation and Procedures CAUTION: Work under appropriate safety conditions.
See “Comments” for preparation of reagents. The dispensing of reagents is completely automated:
- 2 mL acid sample are added into the titration beaker. Uranium is present as UO2
2+ (VI) or UO2+ (IV) in solution.
- 2.5 mL sulphamic acid is added by a burette. Sulphamic acid destroys nitrous acid which can interfere (reducing agents).
- A second burette dispenses 15 mL H3PO4/Fe(II) solution. Ferrous ions reduce U6+ to U4+. Concentrated phosphoric acid complexes U6+ to force completion of reaction.
- A third burette dispenses 3.4 mL HNO3/Sulphamic acid/Molybdate solution. Excess Fe(II) is destroyed using concentrated nitric acid with ammonium molybdate acting as a catalyst. This leads to NO and NO2 which are neutralized with sulphamic acid.
- After 300 s of stir time, 34 mL H2SO4/vanadyl solution is added to the sample by means of a peristaltic pump.
- All uranium is now present as U4+. This could be titrated directly with dichromate but the kinetics is very slow. Thus, vanadyl solution is added to the sample solution. U4+ reacts with vanadyl, VO2+ giving V3+.
- V3+ can be now titrated with potassium dichromate according to equation 2 (see “Chemistry”).
Remarks
Literature: 1. ASTM C1267-06,
“Standard Test Method for Uranium by Iron (II) Reduction in Phosphoric Acid Followed by Chromium (VI) Titration in the Presence of Vanadium”, 2006.
2. ISO 7097-1:2004, “Nuclear fuel technology -- Determination of uranium in solutions, uranium hexafluoride and solids -- Part 1: Iron(II) reduction/potassium dichromate oxidation titrimetric method”, 2004.
3. Davies, W., Gray, W., Talanta 11 (1964), p. 1203. 4. Eberle, A.R., Lerner, M.W., Goldbeck, C.G., Rodder,
C.J., NBL Report 252 (1970). 5. Karekar, C.V., Chander, K., Nair, G.M., Natarajan,
P.R., J. Radioanal. Nucl.Chem.Letters 107(5), pp. 297-305, 1986.
Sample Uranium solution -U(VI), U(IV)- , 2 mL
Compound Uranium, U M = 238.03 g/mol , z = 1
Chemicals - 1 and 1.5 M Sulfamic acid, (NH2)SO3H - 85% Orthophosphoric acid, H3PO4 - 70% Nitric acid (sp. gr. 1.42), HNO3 - Iron(II)sulfate hydrate, FeSO4*7H2O, - 98% Sulfuric acid (sp. gr. 1.84) H2SO4, - Vanadyl sulfate, VOSO4, - Ammonium molybdate,
(NH4)6Mo7O24*4H2O
Titrant Potassium dichromate, K2Cr2O7
c(⅓ K2Cr2O7) = 0.0135 mol/L
Standard (CH2NH3)2SO4*FeSO4*4H2O (see M031, Brochure 9)
Indication DMi140-SC (Pt ring) combined redox electrode
Chemistry 1) Reaction of V with U4+: U4+ + 2 VO2+ → UO2
2+ + 2 V3+ 2) Titration of vanadium: Cr2O7
2-+ 6 V3++ 2 H+ → 2 Cr3++ 6 VO2+ + H2O
Calculation U content (g/L): R1 = Q*C/m C = M/z
Waste disposal
Disposal as radioactive waste (uranium waste)
Author, Version
Russel May, MT-AUS, Feb 1994 Revised February 2010
METTLER TOLEDO Page 1 of 5 Titration Application M292-2010
METTLER TOLEDO Page 2 of 5 Titration Application M292-2010
Instruments - T70/T90 Titration Excellence with LabX titration - XS205 Balance
Other titrators: This method can be also run with the DL70ES and DL77 instruments.
Accessories - 4 x 10 mL DV1010 burettes + dosing tube adapter 4 to 1 ME-51108356 - 3 dosing unit ME-51109030 - PP titration beaker ME-101974 - SP250 Peristaltic pump ME-51108016
Comments
Principle: - Uranium samples are generally strong acid solution containing e.g. nitric acid used for dissolution of
the sample. Pure uranium, uranium alloys, UO2 powders and pellets, U3O8, U/Zr, U/Al, and so on can be dissolved using strong acid mixtures of HNO3, HF and HCl in various ratio.
- Dissolved uranium ions are present in the sample solution as U(IV) and U(VI), e.g. U4+ and U6+. - Uranium (VI) is reduced to uranium (IV) by excess iron (II) in concentrated phosphoric acid containing
sulfamic acid. - The excess amount of iron Fe(II) is selectively oxidized by nitric acid (HNO3) in the presence of a
molybdenum(VI) catalyst. - The nitrogen oxides (NO, NO2) formed during reduction of Fe (II) are neutralized by sulfamic acid.
This is necessary since they are reducing agents and thus they interfere with the analysis. - After the addition of a vanadium (IV) solution, uranium (IV) reacts with it leading to vanadium (III).
Vanadium (III) is titrated with chromium (VI) since the direct titration of U (IV) is very slow.
Preparation of reagents: 1. 1 and 1.5 mol/L sulfamic acid solutions, (NH2)SO3H.
Sulfamic acid is used to neutralize nitrogen oxides.
2. Orthophosphoric acid solution, H3PO4: Add 2 mL 0.1 mol/L K2Cr2O7 solution and fill up to 500 mL with 85% H3PO4.
3. Ferrous sulfate solution: - Add 50 mL 98% H2SO4 to 350 mL H2O and stir. - Add 140 g FeSO4*7H2O, stir and cool to room temperature. - Dilute to 500 mL with H2O.
4. 0.9 M sulfuric acid, H2SO4
5. H3PO4/Fe2+ solution: - Add 65 mL of ferrous sulfate solution (3) to 500 mL orthophosphoric acid solution (2), and mix well. This solution reduces all the present U6+ to U4+ with excess Fe2+.
6. 8 M HNO3/Sulfamic acid/Ammonium molybdate solution: - Dissolve 2 g ammonium molybdate in 200 mL H20. - Add 250 mL 70% HNO3 and cool down to room T. - Add 50 mL 1.5 M sulfamic acid. - Dilute to 500 mL with H2O. Nitric acid neutralizes excess Fe(II) and ammonium molybdate acts as a catalyst.
7. 0.9 mol/L H2SO4/VOSO4 solution: - Add 0.5 g VOSO4 to 500 mL 0.9 mol/L H2SO4 .This solution has to be prepared weekly.
8. Potassium dichromate titrant, K2Cr2O7: - M(K2Cr2O7) = 294.185 g/mol , c(1/3 K2Cr2O7) = 0.0135 mol/l - Dissolve approx. 1.32 g in 1 L volumetric flask, and dilute with water up to the mark.
METTLER TOLEDO Page 3 of 5 Titration Application M292-2010
Chemical equations
In concentrated phosphoric acid solution U(VI) is reduced to U(IV):
UO22+ + 2 Fe2+ + 4 H+ → U4+ + 2 Fe3+ + 2 H2O
• Excess iron (II) is selectively oxidized by nitric acid (HNO3) in the presence of a molybdenum(VI) catalyst.
3 Fe2+ + NO3- + 4 H+ → 3 Fe3+ + NO + 2 H2O
Fe2+ + NO3- + 2 H+ → Fe3+ + NO2 + H2O
• The nitrogen oxides (NO, NO2) formed during reduction of Fe(II) are neutralized by sulfamic acid. This is necessary since they are reducing agents and thus they interfere with the analysis.
• After the addition of a vanadium (IV) solution, uranium (IV) reacts with it leading to vanadium (III).
U4+ + 2 VO2+ → UO22+ + 2 V3+
• Vanadium (III) is titrated with chromium(VI) since the direct titration of U(IV) is very slow.
Cr2O72- + 6 V3+ + 2 H+ → 2 Cr3+ + 6 VO2+ + H2O
This reaction is equivalent to:
Cr2O72- + 3 U4+ + 2 H+ → 2 Cr3+ + 3 UO2
2+ + H2O
Therefore: 1 mole Cr2O72- corresponds to 3 mole U4+, and z = 3 for potassium dichromate.
Note:
In diluted phosphoric acid solution the following reactions take place:
U4+ + 2 Fe3+ + 2 H2O → UO22+ + 2 Fe2+ + 4 H+
Fe2+ + VO2+ + 2 H+ → Fe3+ + V3+ + H2O
Therefore, it is necessary that the phosphoric acid solution is highly concentrated.
Additional remarks
- This application allows for the titration of 20 up to 200 mg uranium in a sample.
- Systematic errors can arise if part of the VO2+ is oxidized by air to V5+. To prevent this, the vanadyl solution should be prepared in acid medium and frequently checked for V5+.
- To make sure that no errors can occur due to the presence of nitrogen oxides remaining after the Fe2+-NO3
- reaction (oxidation of Fe(II) to Fe(III) with nitrate ions), a stream of CO2 gas is passed into the sample solution during analysis. This will remove the oxides.
- Eberle (see “Remarks”, Literature ref. no. 4) has adapted the titration method of Davies and Gray to achieve a faster method.
- This method is based on the Modified Davies-Gray titration as given in ASTM Standard C1267-06. This application does not replace the ASTM C1267-06 standard.
METTLER TOLEDO Page 4 of 5 Titration Application M292-2010
Method Titration Excellence
001 Title
Type General titration
Compatible with T70 / T90
ID M292
Title U content
Author Mettler Toledo
Date/Time 01.03.2010 10:00:00
Modified at 01.03.2010 10:00:10
Modified by Administrator
Protect No
SOP None
002 Sample
Number of IDs 1
ID 1 Uranium
Entry type Volume
Lower limit 0.0 mL
Upper limit 2.0 mL
Density 1.0 g/mL
Correction factor 1.0
Temperature 25.0°C
Entry Before
003 Titration stand (Manual stand)
Type Manual stand
Titration stand Manual stand 1
004 Dispense
Titrant Sulfamic acid
Concentration 1.0 mol/L
Volume 2.5 mL
Dosing rate 60.0 mL/min
Condition No
005 Stir
Speed 15%
Duration 30 s
Condition No
006 Dispense
Titrant H3PO4/Ferrous
Concentration 1.0 mol/L
Volume 15.0 mL
Dosing rate 60.0 mL/min
Condition No
007 Stir
Speed 30%
Duration 30 s
Condition No
008 Dispense
Titrant HNO3/AmmMolybdate
Concentration 1.0 mol/L
Volume 3.4 mL
Dosing rate 60.0 mL/min
Condition No
009 Stir
Speed 20%
Duration 300 s
Condition No
010 Pump
Auxiliary reagent Sulphuric/vanadyl
Volume [mL] 34.0
Condition No
011 Stir
Speed 70%
Duration 60 s
Condition No
012 Titration (EQP) [1]
Titrant
Titrant 1/3 K2Cr2O7
Concentration 0.0135 mol/L
Sensor
Type mV
Sensor DM140-SC
Unit mV
Temperature acquisition
Temperature acquisition No
Stir
Speed 35%
Predispense
Mode None
Waiting time 0 s
Control
Control User
Titrant addition Dynamic
dE (set value) 8 mV
dV (min) 0.02 mL
dV (max) 0.2 mL
Mode Equilibrium controlled
dE 0.5 mV
dt 1 s
t (min) 3 s
t (max) 30 s
Evaluation and recognition
Procedure Standard
Threshold 150
Tendency Positive
Ranges 0
Add. EQP criteria No
Termination
At Vmax 15 mL
At potential No
At slope No
After number of
recognized EQPs Yes
Number of EQPs 1
Combined termination
criteria No
Accompanying stating
Accompanying stating No
Condition
Condition No
013 Calculation R1
Result U content
Result unit g/L
Formula R1=Q*C/m
Constant C= M/z
M M[Uranium]
z z[Uranium]
Decimal places 5
Result limits No
Record statistics Yes
Extra statistical
functions No
Send to buffer No
Condition No
014 End of sample
Note:
1. The method can be easily modified to be run on T50 and
T70 Titration Excellence instruments.
2. M[Uranium]=238.030 g/mol, z[Uranium]=1
3. M[K2Cr2O7]=294.185 g/mol, z[K2Cr2O7]=3
METTLER TOLEDO Page 5 of 5 Titration Application M292-2010
DL70ES and DL77 Titrators
Method T003 U by Davies Gray
Version 15-Feb-1994 11:50
Title
Method ID . . . . . . . . . . . . . T003
Title . . . . . . . . . . . . . . . U by Davies Gray
Date/time . . . . . . . . . . . . . 15-Feb-1994 11:50
Sample
Number samples . . . . . . . . . . . 1
Titration stand . . . . . . . . . . Stand 1
Entry type . . . . . . . . . . . . . Volume U
Lower limit [mL] . . . . . . . . 0.0
Upper limit [mL] . . . . . . . . 2.0
ID 1 . . . . . . . . . . . . . . . . Uranium
Molar mass M . . . . . . . . . . . . 238.03
Equivalent number z . . . . . . . . 1
Instruction
Instruction . . . . . . . . . . . . Aliquot sample
> . . . . . . . . . . . . . . . . .
> . . . . . . . . . . . . . . . . .
Dispense
Titrant . . . . . . . . . . . . . . Sulphamic acid
Concentration [mol/L] . . . . . . . 1.0
Volume [mL] . . . . . . . . . . . . 2.5
Stir
Speed [%] . . . . . . . . . . . . . 10
Time [s] . . . . . . . . . . . . . . 30
Dispense
Titrant . . . . . . . . . . . . . . H3PO4/Ferrous
Concentration [mol/L] . . . . . . . 1.0
Volume [mL] . . . . . . . . . . . . 15.0
Stir
Speed [%] . . . . . . . . . . . . . 30
Time [s] . . . . . . . . . . . . . . 30
Dispense
Titrant . . . . . . . . . . . . . . HNO3/Amm molyb
Concentration [mol/L] . . . . . . . 1.0
Volume [mL] . . . . . . . . . . . . 3.4
Stir
Speed [%] . . . . . . . . . . . . . 30
Time [s] . . . . . . . . . . . . . . 300
Pump
Auxiliary reagent . . . . . . . . . Sulphuric /vanad
Volume [mL] . . . . . . . . . . . . 34.0
Stir
Speed [%] . . . . . . . . . . . . . 70
Time [s] . . . . . . . . . . . . . . 60
Titration
Titrant . . . . . . . . . . . . . . K2Cr2O7
Concentration [mol/L] . . . . . . . 0.0042
Sensor . . . . . . . . . . . . . . DM140-SC
Unit of meas. . . . . . . . . . . . mV
Titration mode . . . . . . . . . . . EQP
Titrant addition . . . . . . . . DYN
dE(set) [mV] . . . . . . . . . 8.0
Limits dV . . . . . . . . . . Absolute
dV(min) [mL] . . . . . . . 0.02
dV(max) [mL] . . . . . . . 0.2
Measure mode . . . . . . . . . . EQU
dE [mV] . . . . . . . . . . . 0.5
dt [s] . . . . . . . . . . . 1.0
t(min) [s] . . . . . . . . . 3.0
t(max) [s] . . . . . . . . . 30.0
Threshold . . . . . . . . . . . . 150.0
EQP range . . . . . . . . . . . . Yes
Limit A [mV,pH,...] . . . . . -1000
Limit B [mV,pH,...] . . . . . 1000
Maximum volume [mL] . . . . . . . 15.0
Termination after n EQPs . . . . Yes
n = . . . . . . . . . . . . . 1
Evaluation procedure . . . . . . Standard
Steepest jump only . . . . . . . Yes
Calculation
Result name . . . . . . . . . . . . Uranium
Formula . . . . . . . . . . . . . . R=(Q*C)/U
Constant . . . . . . . . . . . . . . C=M/z
Result unit . . . . . . . . . . . . g/L
Decimal places . . . . . . . . . . . 5
Statistics
Ri (i=index) . . . . . . . . . . . . R1
Standard deviation s . . . . . . . . Yes
Rel. standard deviation srel . . . . Yes
Record
Output unit . . . . . . . . . . . . Printer
Results last sample . . . . . . . . Yes
Remarks:
1. The original version of this method has the following
calculation.
Calculation
Result name . . . . . . . . . . . . Uranium
Formula . . . . . . . . . . . . . . R=VEQ*C/U
Constant . . . . . . . . . . . . . . C=5
Result unit . . . . . . . . . . . . g/L
Decimal places . . . . . . . . . . . 3
With
Titration
Titrant . . . . . . . . . . . . . . K2Cr2O7
Concentration [mol/L] . . . . . . . 0.0042
2. The content is calculated directly form the titrant
consumption to the EQP (VEQ). Thus, it seems that a
conversion factor in mg U/mL titrant has been used as a
titer for the titrant.
This conversion factor may be given in the constant C=5.
This application bulletin represents selected, possible application examples. These have been tested with all possible care in our lab with the analytical instrument mentioned in the bulletin. The experiments were conducted and the resulting data evaluated based on our current state of knowledge.
However, the application bulletin does not absolve you from personally testing its suitability for your intended methods, instruments and purposes. As the use and transfer of an application example are beyond our control, we cannot accept responsibility therefore.
When chemicals and solvents are used, the general safety rules and the directions of the producer must be observed.
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Selected Applications for Titration
in Metals Mining
This brochure contains dedicated applications for the determination
of metals in various mining samples.
The titration analyses of ferrous and base metals as well as
precious metals such as gold and silver are described in a detailed
and comprehensive way that allows easy adaptation to the specific
sample.
In addition, the titration of auxiliary reagents frequently used
in
mining engineering such as cyanide salts is presented.
METTLER TOLEDO offers you various powerful tools for titration in
metals mining which are meant to facilitate your content
determination analyses and to contribute to reliable results over the
whole lifetime of your instrument.
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