Research poster presented in Undergraduate Research Symposium '12

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Extraction Of Metal Using Liquid Emulsion Membrane Technique
Varun Dameera, Hemant Bansal, Sonali Kulkarni and Prof. V. A. Juvekar
Department of Chemical Engineering, IIT Bombay, Powai, Mumbai – 400 076
Introduction
Results
Conclusion
5mm
Objectives
To carry out extraction from the dilute solution of iron
To study the effects of the following parameters on the extraction process
Acidity of feed phase
Concentration of iron in the feed phase
Experimental Method
,
Preparation of stable emulsion
Water in oil emulsion
Continuous phase: Light liquid paraffin oil
Carrier / extractant: TBP (Tri-butyl phosphate)
Surfactant: Abil WE 09 (polysiloxane polyalkyl polyether copolymers)
and Polyacrylamide co-acrylic acid
Dispersed phase: Aq. NaOH Solution
Method of preparation:
Aqueous phase is dispersed in continous phase. Continuous phase contains carrier and surfactants
Dispersion is carried out with Ultra Turrax Digital homogenizer
Acknowledgement & Contact
The authors would like to acknowledge Board of Research in Nuclear Science (BRNS), BARC, Mumbai for financial support.
Contact:
Varun- 10D020047@iitb.ac.in , Hemant- hemantbansal@iitb.ac.in,
Sonali- ksonalinsk@gmail.com, Prof.V.A. Juvekar-vaj@iitb.ac.in.
Challenges associated with LEM extraction process
1. Ahmad, A. L., A. Kusumastuti, et al. "Emulsion liquid membrane for heavy metal removal: An overview on emulsion
stabilization and destabilization." Chemical Engineering Journal 171(3): 870-882.
2. Albers, W. and J. T. G. Overbeek (1960). "Stability of emulsions of water in oil III. Flocculation and redispersion of water
droplets covered by amphipolar monolayers." Journal of Colloid Science 15(6): 489-502.
3. Bart, H. J., H. Jungling, et al. (1995). "Water and solute solubilization and transport in emulsion liquid membranes."
Journal of Membrane Science 102(0): 103-112.
IKA – Digital Ultra Turrax Emulsifier
Nikon Eclipse TE2000U Inverted
Microscope with DS Fi1 Camera
Equipments:
References
Liquid emulsion membranes ( LEMs) are improved solvent extraction
technique that found application in liquid waste treatment and
hydrometallurgy. In this process, the solute is extracted from its dilute
aqueous solution to another aqueous medium, through the liquid
membrane of immiscible phase separating the two aqueous media.
It consists of a feed phase containing the solute to be extracted. It is
extracted in another aqueous phase called as strip phase through the
membrane of an organic phase. W/O emulsion is dispersed in the
feed phase to form W/O/W double emulsion. The mass transport of
the solute occurs from the feed phase to the internal water phase of
the emulsion globule.
Leakage
Membrane
Feed phase
Occlusion
Emulsion globule
feed phase (water) feed phase (water)
Emulsion globule
After
7 minutes
Coalescence
Mass Transfer
M
+
M+M
+
M
+
M
+
M
+
M
+
M
+
M
+ M
+
M
+
Carrier
Surfactant
Molecule
M+ = Metal ion
 Coalescence leads to leakage of the internal droplets into the
feed phase. This causes loss of extracted solute again goes into
the feed phase.
Water from the feed phase gets occluded in the emulsion
globule and causes dilution of the strip phase.
Suitable driving force and carrier molecules are required to
carry out the mass transfer from outer feed phase to the internal
strip phase across the oil membrane.
The emulsion prepared is observed under the
microscope to check the stability against
flocculation and coalescence.
Extraction
• Composition of feed phase:
-Ammonium ferric sulphate solution prepared in HCl with different molarity
• Freshly prepared emulsion is dispersed in the feed phase and stirred for some time
• Emulsion is separated from feed phase
• Change in the concentration of the feed phase is measured with UV spectro-photometer
Emulsion without surfactant Emulsion with excess surfactant
Stable emulsion with 2% v/v surfactant
on the basis of cont. phase
Emulsion stability: No coalescence and No flocculation.
Distribution constant at different concentration of
HCl in feed phase :
K= Conc. of iron in oil / conc. of iron in aq. phase
(at equilibrium)
0
20
40
60
80
100
120
140
160
180
200
2 3 4 5 6
K-value
Molarity (mols/lit)
K-value vs Concentration
0
20
40
60
80
100
120
0 500 1000 1500
%Extraction
Conc. of iron (ppm)
% Extraction vs Concentration
of iron
% extraction vs conc of
fe
ConK 
% extraction at different conc. of iron in the feed
phase :
% Extraction= (Initial conc. of iron in feed phase-conc.
of iron after extraction)/ Initial conc. of iron*100
Discussion
Emulsion stability is the critical parameter in LEM. It highly depends upon the nature of continuous and
disperse phase, type of surfactant and its concentration
 Normality of feed phase controls the extraction process. We found that the maximum extraction occurs at 4M
concentrated HCl solution.
In this system, as conc. of iron increases, extraction efficiency decreases from 100% at 100ppm to 40% at
1000ppm of iron concentration.
There exist critical concentration of HCl which gives maximum recovery of iron.
Extraction efficiency reduces with concentration of iron. This may be because of formation of the coat of iron
at the interface of the emulsion globule.