AVR$SVR COLLEGE OF ENGINEERING: KURNOOLCIVIL ENGINEERING DEPARTMENT

IV B.TECH. (SCHEME –2009)ENVIRONMENTAL ENGINEERING LABORATORY

TITLE: Test Procedure to determine amount of Sulphates in a Water Sample

1.AIM :To determine the amount of Sulphates present in the given water sample(s).

2.APPARATUS:Burette (50ml) with burette stand, Pipette (20ml), Conical flasks (250ml), Beaker (100ml), Measuring jar (100 ml), Filter stand and Whatman filter paper no.40.

3.REAGENTS:Standard Sodium hydroxide (NaOH), Benzidine hydrochloride and Phenolphthalein indicator.

4.PRINCIPLE: The Sulphate ions will get precipitated as insoluble benzidine sulphate when water is treated in cold, with binzidine hydrochloride solution. However this precipitate is soluble in hot water and hydrolyses in to benzidine hydride and sulphuric acid. This sulphuric acid is titrated against a standard sodium hydroxide solution using phenolphthalein as indicator.

5.PROCEDURE:1. Clean all the apparatus with distilled water and rinse with respective

solutions.2. Pipette out 100 ml of water sample in to a 250 ml clean conical

flask. 3. Add 40 ml of benzidine hydrochloride solution and mix thoroughly.4. Allow the solution for 15 minutes to form the precipitate.5. Filter the precipitate through a whatman filter paper no. 40 and

wash the precipitate with cold distilled water to free from acid.6. Transfer the filter paper along with precipitate in to a conical flask

and add to it about 50 ml of distilled water.7. Warm the solution to about 50oC (till the first bubble appears) to

dissolve the precipitate.8. Titrate the liberated sulphuric acid against standard sodium

hydroxide solution using phenolphthalein as indicator. Permanent light pink colour observed as end point.

9. Note the amount of sodium hydroxide used.10.Repeat the same procedure for concurrent values of burette

readings.11.Repeat the above procedure for the given any number of samples.

6.OBSERVA TIONS:

S.No. Description Volume of Burette readings Volume of

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AVR$SVR COLLEGE OF ENGINEERING: KURNOOLCIVIL ENGINEERING DEPARTMENT

IV B.TECH. (SCHEME –2009)ENVIRONMENTAL ENGINEERING LABORATORY

TITLE: Test Procedure to determine amount of Sulphates in a Water Sample

of sample Sampletaken (ml)

NaOHused (ml)

Initial (ml)

Final (ml)

7.CALCULATIONS:Normality of NaOH solution (N) =

Volume of NaOH required for sample (A) =

Amount of Sulphates = A x N x 48 x 1000 mg/litre Volume of sample

8.RESULT: The amount of sulphates present in the water sample =

9.INFERENCE:The given water sample may/may not be used for domestic purpose. The given water sample may/may not be used for construction purpose.

10.PUBLIC HEALTH SIGNLFICANCE: Sulphates data is of importance in public water supplies because of its cathartic effect upon humans when it is present in excessive amounts. Sulphates are responsible for two serious problems such as odor and severe corrosion problems. These are resulting from the reduction of sulphates to hydrogen sulphide under anaerobic conditions. At pH levels below 8, sulphate reduction yields a significant amount of sulfide ions which leads to formation of un ionized H2S. This H2S causes serious Odor problems.

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