O - Alive2green

Removal of Cr(VI) from Aqueous Solution by Smart
Polymers and their Nanocomposites
Dr. Arjun Maity
Smart Polymers Group
Polymers and Composites
Materials Science and Manufacturing
Council for Scientific and Industrial Research
www.csir.co.za
© CSIR 2010 Slide 1

Introduction
Health effects
Outline
Purification technology
Nanotechnology
Objectives
Synthesized adsorbents
Characterization
Application for Cr(VI)
Conclusion
© CSIR 2010 Slide 2

Chrome industry
Automobile
Petroleum refining
Pulp & Paper
Textile
Steel
Organic & Inorganic Chemicals
Metal plating
Etc.
Background
Wastewater
discharge
Heavy metals
© CSIR 2010 Slide 3
Affected natural water resources

Chromium Chemistry
Speciation diagram of Cr(VI)
Surface water = 0.1 mg/L
Potable water = 0.05mg /L
© CSIR 2010 Slide 4
US-EPA

- Upset stomachs and ulcers
- Respiratory problems
-Internal haemorrhage
- Weakened immune systems
- Kidney and liver damage
- Alteration of genetic material
- Lung cancer
- Death
Health effects of chromium
© CSIR 2010 Slide 5
Liver
damage
Lung
cancer

Chemical precipitation
Ion exchange
Purification Technologies
Membrane separation
Electrocoagulation
© CSIR 2010 Slide 6
Solvent extraction
Electrodialysis

Adsorption
Adsorption and Adsorbents
Activated carbon
Chitosan based materials
© CSIR 2010 Slide 7
Ion – exchange resin
starch based
materials

Nanotechnology
Nano-adsorbent
Large surface area, accessible active sites, short diffusion length
Magnetic Separation
Simplicity, effective control, high speed, accuracy
© CSIR 2010 Slide 8

Objectives
To synthesis of the conducting polymer based low cost materials
To characterize the adsorbents using various physico-chemical
techniques
To evaluate the performance of the adsorbents for Cr (VI)
removal in batch sorption mode
To study the effect of temperature, time, solution pH and
adsorbent dose on the adsorption
© CSIR 2010 Slide 9

PPy doped with Cl -
High electrical conductivity
Relatively good environmental stability
Non-toxicity
Relatively low cost
Ease of preparation
Ion-exchange properties
Conducting Polymer
© CSIR 2010 Slide 10

Aqueous medium
PPy/Fe 3 O 4 Magnetic Adsorbent
Py
Fe 3O 4
FeCl 3 oxidant
Room temperature
PPy/Fe 3 O 4 Nanocomposites
Bhaumik et al Journal of Hazardous Materials, 186 (2011) 150-156.
Bhaumik et al Journal of Hazardous Materials, 190 (2011) 381-390.
© CSIR 2010 Slide 11
PPy
Fe 3O 4

SEM images of (a) Fe3O4 (b) PPy/Fe3O4 nanocomposites
PPy
FE-SEM and HR-TEM Images
Iron Oxide
(a) (b)
PPY
HR-TEM Image
© CSIR 2010 Slide 12
Iron Oxide

Intensity / a. u.
XRD Studies
< 220 >
< 311 >
< 400 >
10 20 30 40
2θ / degree
50 60 70
© CSIR 2010 Slide 13
< 422 >
< 511 >
< 440 >
XRD curves of (A) & (B) PPy/Fe 3 O 4 nanocomposites before and
after adsorption with Cr(VI)
(A)
(B)

Intensity / a. u.
15 00
10 00
5 00
0
-5 00
-1 0 00
-1 5 00
ESR Studies and Photographs
(a ) PP y/F e 3 O 4 na noc omposite
b efore adsorption
(b ) P Py/F e 3 O 4 nanocomposite
a fter adsorption
0 10 0 2 00 30 0 40 0 500 60 0 700
M agnetic field / mT
(b )
(a)
© CSIR 2010 Slide 14
Nanocomposites
before adsorption
after adsorption

% of removal
100
80
60
40
20
0
Effect of pH
Temperature = 25
PPy
Fe O
3 4
PPy/Fe O
3 4
O C
Dose = 2 g/L
0 2 4 6
pH
8 10 12
© CSIR 2010 Slide 15
Initial concentration = 200 mg/L

% of Cr (VI) removal
100
80
60
40
20
0
Effect of Dose
0 50 100 150 200 250 300
dose (mg)
© CSIR 2010 Slide 16
Initial Conc = 200 mg/L
pH = 2

Adsorption capacity / (mg/g)
100
80
60
40
20
0
Kinetic Studies
0 50 100 150 200 250 300 350 400
Time / minute
© CSIR 2010 Slide 17
Dose = 1 g / L
pH = 2
50 mg/L
100 mg/L
150 mg/L

q e / (mg/g)
240
220
200
180
160
140
120
100
80
Effect of Temperature
0 50 100 150 200 250 300
C e / (mg/L)
© CSIR 2010 Slide 18
25 O C
35 O C
45 O C
pH = 2.0, Dose = 2 g / L

Intensity / a. u.
774 901
826
ATR-FTIR Analyses
958
1080
1423
Nanocomposites after adsorption
Nanocomposites before adsorption
1513
800 1200 1600 2000 2400
Wavenumber / cm -1
© CSIR 2010 Slide 19
O
O
Cr
O-
OH
774 cm -1 ------Cr - O
901 cm -1 -------Cr = O

Intensity / a. u.
C O
Fe
N
Al
(a) PPy/Fe 3 O 4 nanocomposites before adsorption
(b) PPy/Fe 3 O 4 nanocomposites after adsorption
Cl
Cl
(a) (b)
0 1 2 3 4 5 6 7
Energy / KeV
EDX and XPS studies
Cr
Cr
Fe
Fe
C / S
1.2 10 4
1 10 4
8000
6000
4000
2000
© CSIR 2010 Slide 20
Cr2p 3/2
Cr(III)
Cr2p 1/2
Cr(VI)
0
550 560 570 580 590 600 610 620
Binding energy / eV

HCrO 4 -
Mechanistic Aspect
HCrO 4 -
© CSIR 2010 Slide 21
HCrO 4 -

Adsorption and Separation of Adsorbent
© CSIR 2010 Slide 22

Comparison of Adsorption Capacity
Adsorbents qm (mg/g) Equilibrium
time(h)
Activated carbon
Activated carbon coated with quarternized poly(4vinylpyridine)
Amorphous aluminium Oxide 78
15.47 3 4.0
53.7 24 2.25
Diatomite-supported magnetite nanoparticles 69.16 1 2.0
Hydrous zirconium oxide 61 1 2.0
Surface modified jacobsite 31.55 0.08 2.0
Oxidised multiwalled carbon nanotubes 2.60 280 2.88
Bio-funtional magnetic beads 5.79 12 1.0
Nanocrystalline akaganeite 79.66 1.0 5.5
Polyaniline-polyethylene glycol composite 68.97 0.50 5.0
Polypyrrole/ wood sawdust 3.4 0.16 5.0
Polypyrrole/F 3 O 4 magnetic nanocomposite 169.4 0.50-3 2.0
© CSIR 2010 Slide 23
Optimum
pH

Adsorption capacity/ (mg/g)
100
80
60
40
20
0
Regeneration Study
1 2 3
Adsorption cycle
© CSIR 2010 Slide 24

n
n
H N
Pyrrole
H
N
Pyrrole
+ FeCl 3
+
APS
Cl -
Glycine doped PPy - Adsorbent
- OOC-CH2-NH 3 +
Zwitter ion
pH = 5.03
Ballav et al Journal of Hazardous Materials, Submitted, 2011
H
Polypyrrole-Cl
H
N*
+ Cl -
N*
+
*
n
- OOC-CH2-NH 3 +
*
n
Polypyrrole-glyicne
© CSIR 2010 Slide 25

% of Cr (VI) removal
q t / (mg/g)
120
100
80
60
40
20
Initial conc = 200 mg/L
Dose = 2 g/L
PPy/Gly
PPy
0
0 2 4 6 8 10 12
60
pH
50
40
30
20
10
Dose = 2 g/L, pH = 2
0
0 50 100 150
t / minute
200 250 300
Adsorption and Mechanism
50 ppm
75 ppm
100 ppm
+
H3N -
HCrO 4 H3 N
© CSIR 2010 Slide 26
+
N +
O -
H
N
N
H H
H
+
H3N O
N +
O -
H
N
-
HCrO 4
H
N
N +
-
O
N
H H
H
- +
HCrO 4 H3N O
H
N
N +
-
O
O
O

% of Cr(VI) removal
Glycine doped PPy/ Fe 3 O 4 magnetic nanocomposite
120
100
80
60
40
20
0
Initial concentration = 200 mg / L
pH = 2.0
0.025 0.075 0.125 0.175 0.225 0.275 0.325 0.375
Dose / g
Ballav et al under communication
Uptake / (mg / g)
60
50
40
30
20
© CSIR 2010 Slide 27
100 mg / L
50 mg / L
Dose = 2 g / L
pH = 2
10
0 50 100 150 200 250 300 350
Time / min

NH
H
N
+
Cl
PPy-PANI Nanotubes Adsorbent
H
N NH
+
Cl
Polyaniline sequence
NH N
HCrO 4 -
+ +
HCrO 4 -
H
N NH
HCrO 4 -
H
N
H
N
Bhaumik et al Journal of Colloid and Interface Science, Submitted, 2011
Cl
+
N
H 2
N
H2 - HCrO 4
H
N
Polypyrrole sequence
+
H
N
© CSIR 2010 Slide 28
PPy/Cl
BET Surface area 2 m 2 /gm
PPy-PANI Nanotubes
BET Surface area 59.71 m 2 /gm

% of removal
100
80
60
40
20
Copolymer
PPY
Initial concentration=100 mg/L
Temperature=25 O C
Adsorption
0
2 4 6 8 10 12 14
pH
q t / (mg/g)
100
80
60
40
20
© CSIR 2010 Slide 29
0
Dose= 1g/L
pH=3.0
50mg/L
75mg/L
100mg/L
0 100 200 300 400
t / min

% of Cr(VI) removal
100
80
60
40
Initial conc = 200 mg/L
Dose = 2 g/L
Composite
PPy/Cl
20
0 2 4 6
pH
8 10 12
Maity et al
Other Adsorbent
Uptake
60
50
40
30
20
10
© CSIR 2010 Slide 30
Dose = 2 g/L
pH = 2
100 ppm
50 ppm
0
0 20 40 60 80 100 120 140
Time / min

SEM
POM
Maity et al
α-Cellulose
Fabrics of Sterculia urens-Adsorbent
% of Cr(VI) removal
110
100
90
80
70
60
50
40
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Effect of dose / g
© CSIR 2010 Slide 31
Initial concentration = 100 mg/L
pH= 2.0, 25 mL solution

Conclusions
The adsorbents were highly efficient for the removal of Cr (VI)
from water
The Cr (VI) uptake was depended on the initial concentration,
temperature, adsorbent dose and pH
The adsorption process was endothermic in nature
Adsorption proceeded by ion exchange mechanism
Further experiments are still required to apply the materials
for industrial wastewater treatment and to possibly upgrade to
magnetic adsorption process
© CSIR 2010 Slide 32

Acknowledgement
Dr. Sean Moolman
Mrs Avashnee Chetty
Prof. Maurice S Onyango, TUT, SA
Prof. VV Srinivasu, UNISA, SA
Prof. Rotimi Sadiku, TUT, SA
Mr Pramod Sinha, UNISA, SA
Dr. UC Ghosh, CU, India
Dr. S. B. Mishra, UJ, SA
Post docs
Students
© CSIR 2010 Slide 33

Thank You
© CSIR 2010 Slide 34