polymer based nanocomposites for the removal of cr(vi
TRANSCRIPT
Polymer based nanocomposites for the removal
of Cr(VI) from water
Emerging Researcher Symposium
Katlego Setshedi
10 October 2012
Outline
© CSIR 2012 Slide 2
• Background
• Problem statement
• Health impacts
• Remedies
• Objectives
• Experimental procedure
• Results
– Characterization
– Batch sorption
– Continuous sorption
• Conclusions
Background
The water industry faces problems on national and global level that
needs to be addressed:
© CSIR 2012 Slide 3
•Fresh water reduces due to droughts
•Chemical (metals, fluoride, nitrate and other
chemicals) and biological contamination
•Acid mine drainage
•Little/disregard for the environmental
consequences of INDUSTRIAL activity
Alloy manufacturingElectroplating
Effluent
Cr, Ni, Cu, Pb,
Hg, Cd, As, Fe…
Abandoned mines
Acid mine drainage Wastewater discharge to
surface water
Industrialization & Heavy-metals – The problem
Health effects
© CSIR 2012 Slide 5
Drinking water containing Heavy metals (even at low concentrations) can cause:
•Skin cancer
•Liver damage
•Mental retardation
•Carcinogenic
•Kidney damage
Precipitation
Electrodialysis Membrane separationSludge disposal problem
Ineffective @ low conc. High Cost High Cost
FoulingAdsorption
Robust in nature
Mass transfer resistance
Nanotechnology (Nanosorbents)
Characteristics:
•large surface area
•potential for self assembly
•high specificity
•high reactivity
•catalytic potential
-
Our approach
Conventional technologies Vs our approach
(Savage and Diallo, 2005)
Adsorbents
Fe3O4
PPy
Fe3O4
PPy
PPy/Fe3O4 Nanocomposites
Polymer/Clay nanocomposites
Exfoliated clay
sheets
Polymer
Advances in nanoscale science and engineering
(Bhaumik et al., 2011)
(Present study)
• To synthesize and characterize polymer based nanocomposites for Cr(VI) removal
from wastewater
• To perform batch adsorption equillibria and kinetics under controlled conditions
• To relate sorbent performance with sorbent properties and water quality
• To apply existing mathematical models to describe isotherms and kinetic data for
design parameters
• To test the applicability of the material with real groundwater containing Cr(VI)
• To test the regenerability of the sorbent
• Evaluate sorption performance in a continuous system
Objectives
Preparation of the exfoliated polypyrrole/OMMT nanocomposites
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H2O + EtOH + OMMT clay
H2O + EtOH
OMMT clay
sheets
Pyrrole( ) FeCl3
Oxidant
Polypyrrole
Exfoliated clay
sheets
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Swelling with water
and EtOH
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Novel magnetic polymer based nanocomposite
•Highly dispersible
•Easy separation
•Use of high gradient magnetic
separator
Adsorbent preparation
Variables
•Temperature
•Initial concentration
•pH
•Sorbent dose
Speed
control
Six-blade impeller
Rxn.vessel
Sorbent :Polymer
based NC
Cr(VI) –
spiked waterWater bath shaker
Sorption kinetics study:
-Determination of reaction kinetic parameters
Sorption isothermsSorption kinetics
Batch equilibrium and kinetics
0 1 2 3 4 5 6
Inte
nsi
ty /
a.u
.
2 degree
(a)
(b)
(B)(a) OMMT
(b) PPy-OMMT NC3
4 6 8 10 12 14
Inte
nsi
ty /
a.u
.
2 degree
(a)
(b)
(A)
7.05
(a) OMMT
(b) PPy-OMMT NC3
Small angle X-ray diffraction patterns of (a) OMMT and
(b) PPy-OMMT NC
Wide angle X-ray diffraction patterns of (a) OMMT and
(b) PPy-OMMT NC
Characterization
XRD
Results
800 1200 1600 2000 2400
Tra
nsm
itta
nce
/ a
.u.
Wavenumber / cm-1
(a)
(b)
824958
1081
1423 1513
773
891
(a) PPy-OMMT NC3 before
Cr(VI) adsorption
(b) PPy-OMMT NC3 after
Cr(VI) adsorption
FTIR spectra of the PPy-OMMT NC (a) before
and (b) after adsorption with Cr(VI)
Transmission electron microscopic image of the
PPy-OMMT NC
OMMT clay – 9.79m2/g
PPy-OMMT NC – 16.076m2/g
ATR-FTIR and TEM analysis
EFFLUENT
PACKED BED
COLUMN
PUMPINFLUENT
NANOCOMPOSITEINERT BEADS
GLASS WOOL
0
20
40
60
80
100
120
0 10 20 30 40 50
5 g
3 g
7 g
Ce (
mg
/L)
Time (hrs)Continuous column adsorption small scale system
Breakthrough curves of Cr(VI) sorption by
PPy-OMMT NCpH 2
Co = 100 mg/L, 298 K, 3 ml/min
30 cm column
2 cm diameter
Column – dynamic study
100
200
300
400
500
600
0 100 200 300 400 500 600 700
298 K
308 K
318 K
Qe (
mg/
g)
Ce(mg/L)
0
20
40
60
80
100
120
0 50 100 150 200 250 300 350
100 mg/L
50 mg/L
75 mg/L
Qe(m
g/g
)Time (min)
Adsorption kinetics of Cr(VI) onto polymer based
magnetic nanocompositeAdsorption isotherms of Cr(VI) onto polymer based
magnetic nanocomposite
Maximum sorption capacity = 335-580 mg/g
o
e
oe
e
q
C
bqQ
C 1
Langmuir isotherm
eet q
t
kqq
t2
1
Pseudo second order kinetic model
Chemisorption
Magnetic polymer based nanocomposites
0
20
40
60
80
100
0 0.05 0.1 0.15 0.2 0.25 0.3
pH 2
pH 6
% R
emo
val
pH
Feasibility test for Cr(VI) contaminated ground water and the effect
of competing ions
100 ppm Cr(VI) sol. Nanocomposite + Cr(VI) sol 0 ppm Cr(VI) sol.
0
20
40
60
80
100
Qe(m
g/g
)
Cr6+
Cr6+
/Ni2+
Cr6+
/Cl-
Cr6+
/Zn2+
Cr6+
/NO3
-Cr
6+/Co
2+
0
20
40
60
80
100
10 20 30 40 50
Cycle 1
Cycle 2
Cycle 3
qe /
(m
g/g
)
Volume of eluent / mL
Adsorption-desorption cycles for PPy-OMMT NC
Adsorption-desorption cycles for polymer based
magnetic nanocomposite
0
20
40
60
80
100
Qe(m
g/g
)
Cycle 1 Cycle 2 Cycle 3
Regeneration studies
• PPy-OMMT and the polymer based magnetic NCs was synthesized and characterized for
Cr (VI) removal from aqueous solution
• PPy-OMMT NC was exfoliated and exhibited effectiveness in the removal of Cr (VI) ions
from aqueous solutions
• Uptake increases with an decrease in pH and an increase in temperature with both
nanocomposites
• Fast removal kinetics– due to low mass transfer resistance for both nanocomposites
• Isotherms were best described by the Langmuir isotherm for both nanocomposites
• Kinetics were best described by the Pseudo second order kinetic model for both
nanocomposites
• Continuous sorption data reveals an effective Cr(VI) sorption with an increase in sorbent
dosage
The removal of Cr (VI) ions as a model heavy metals from aqueous solution was carried
out in a batch and continuous adsorption mode using polymer based NCs
Conclusions
1. Chromium(VI) Removal from Water Using Fixed Bed Column of Polypyrrole/Fe3O4
Nanocomposite, Madhumita Bhaumik, Katlego Zebedius Setshedi, Arjun Maity, Maurice S.
Onyango, Separation and Purification Technology, Under Review, (2012) I.P- 2.92
2. Exfoliated polypyrrole-organically modified montmorillonite clay nanocomposite as a
potential adsorbent for Cr(VI) removal, Katlego Zebedius Setshedi, Madhumita Bhaumik,
Segametsi Songwane, Maurice S. Onyango, Arjun Maity, Water Research,Under review, (2012)
I.P – 4.8
Output
•Dr. Arjun Maity - CSIR supervisor
•Prof. Maurice Onyango – TUT Supervisor
•Avashnee Chetty
•Segametsi Songwane
•Dr. Mamoeletsi Mosia
•National Research Foundation (NRF)
• Council for Scientific and Industrial Research (CSIR)
Acknowledgements
Thank you