Polymer inclusion membranes (PIMs) provide an effective method for separating metal ions using a polymer, carrier, and plasticizer. PIMs offer advantages over other membrane processes like bulk liquid membranes due to using negligible solvent quantities. Current research optimizes PIM composition and examines transport experiments. Common polymers like PVC and CTA are used with carriers like D2EHPA, Aliquat 336, and crown ethers to selectively transport ions. PIM morphology, selectivity, and the effects of parameters like pH and temperature on transport kinetics are areas of ongoing study. Future applications of PIMs include commercial separations in biotechnology, food processing, precious metal recovery, and environmental remediation.

1. Transport Studies of Metal ions Using Polymer
Inclusion Membrane containing Carriers
- Current advances in the Research field
D R . S O U R AB H M U K T I B O D H
P R O F ES S O R O F C H E M I S T RY
M ATA J I JA BA I G O V T. G I R LS P O S T G R A D UAT E C O LLEG E
I N D O R E, I N D I A

2. Why transport studies?
Conventional methods available- Solvent Extraction
Good separation method-
1. High selectivity
2. Easy to handle
Problems?
Large quantities of solvent required.
May be volatile and may create environmental issues
May not be convenient for industrial use

3. Membrane Processes
1. Bulk liquid membranes (BLM`s)
2. Emulsion liquid membranes (ELM`s)
3. Supported liquid membranes (SLM`s)
Limitation of BLM-
1. Low interfacial surface area
2. Low mass transfer rate
Typical emulsion liquid membrane

4. BLM, ELM and SLM Transport
Limitation of ELM-
1.Emulsion breakage
2. Low recovery of metal ion
Limitation of SLM-
1. Poor stability
Impractical for large scale applications

5. Polymer inclusion membrane
1. Effective method of separation
2. Can be used for separation of metal ions, anions and small organic molecules.
3. Low or negligible quantity of solvent will be required.
4. Fast mass transfer and high selectivity
5. Can be used for sensing, particularly electrochemical sensing, such as in making ion selective
electrodes.
6. suitable for industry.

6. Polymer inclusion membrane (PIM)
PIM composition-
1. Polymer – provides mechanical strength
2. Carrier- transports metal ion or rather extracts
3. Plasticizer- Provides elasticity to the membrane

8. PIM Transport Experiments

9. Experiments for the optimization of
PIMs composition
Feed phase PIM Stripping phase
EXPERIMENTAL PROCEDURE AND RESULTS

10. Base Polymers for membrane
preparation
Most common-
1. Poly(vinyl chloride) PVC
2. Cellulose triacetate CTA
Less common-
1.Cellulose acetate propionate CAP
2. Cellulose Tributyrate CTB
Role- 1. Mechanically supporting the membrane
2. enhancing the membrane stability
3. Minimal hindrance to transport

11. Physical properties of Polymers used in
PIM
Polymer MW MWc Tg (0C) Tm(0C) Physical characterstics
PVC 90-180 12.7 80 - Slightly crystalline,
mostly amorphous
CTA 72-74 17.3 - 302 Infusible, high degree
of crystallinity,
excellent strength
CTB 120 474 - 207 Infusible, high degree
of crystallinity,
excellent strength
MW- Molecular Weight
MWc- Critical entanglement Molecular weight
Tg- Glass transition temperature
Tm- Melting temperature

12. PVC CTA
Polymer Properties
PVC C-Cl polar bond, non-specific dispersion forces, amorphous polymer, less crystalline.
Not hydrated, no hydrolysis.
CTA O-H and acetyl groups, polar high degree of crystallinity, can be slightly hydrated and
may get hydrolysed at acidic pH

13. Carriers
Carrier is a complexing agent or chelating agent or ion-exchanger.
Membrane
Polymer+carrier+
plasticizer
Metal ion
Phase-1
Metal ion
Phase-2
Carrier Type Examples
Acidic Alkyl phosphoric acids D2EHPA, Carboxylic
acids
Basic Amines and derivatives, Aliquat 336
Neutral or solvating Phosphoric acid esters, polyethylene
glycol
Macrocyclic and macromolecular crown
ethers calix and arenes
DB18C6, DC18C6

14. D2EHPA
Aliquat 336
DB18C6
DC18C6Polyethelene glycol
TBP
DBBP

15. Ligands that we have used in both bulk liquid membrane and
polymer inclusion membrane
O
O
OOCH3
O O O
O
O
CH3
n
O
O
O
O
O
n
n=1, Ia
n=2, Ib
n=3, IC

16. CYPHOS Ionic Liquids
Description
phosphonium ionic liquids exhibit a broad range of features and benefits that enable unique
solutions for challenging applications. The tunable 3-dimensional nature of the phosphonium
cation enables many physical properties to be tailored to meet specific process requirements.

17. CYPHOS Ionic Liquids
Features Advantages
3-Dimensional structure Increased miscibility with non-polar media
High thermal stability Large temperature operating window
Greater chemical inertness Tolerates harsh process conditions and reagents
Large liquid range
Allows greater flexibility of reaction conditions
Ultra-low vapor pressure
Non-flammable
Electrochemical stability Large electrochemical window
Inherent polarity Conductive materials
Unique dissolution abilities Facilitates separations

18. Plasticizers
Plasticizers are used to increase-
1. Membrane softness and flexibility
2. Flux of metal ions
3. to reduce the strength of intermolecular forces between the polar molecules of the polymer.
Note- in some cases carrier itself acts as a plasticizer

19. Commonly used plasticizer
BBPA
Bis(1-butylpentyl) adipate
DBS
Dibutyl sebacate
NPOE
Nitrophenil octyl ether

20. Target ion/ molecule
1. Most of the research is oriented towards transport of heavy metal ions, their separation and
selectivity.
2. selective transport of alkali an alkaline earth metal ions by macrocycles and related
compounds have also been targeted.
3. small organic molecules like phenols and dye-stuffs have also been reportedly studied under
PIM.
4. removal of antibiotics from water resources is also reported by PIM experiments.
5. radioactive metal ions from waste water is also reportedly separated.
The table follows, containing latest references.

21. PIM Morphology
PIM Morphology is studied by-
1. Atomic force microscopy (AFM)
2. Scanning electron microscopy (SEM)
2. FT-IR
Cross sections of pure polymer, polymer and plasticizer and polymer+plasticizer+ carrier
membrane allows us to examine about the distribution of carrier in the membrane.
These methods allows us to calculate pore size of the nano-channels, membrane permeability
and other physical parameters.

22. Membrane features
1. Thickness – about 50 to 100 micrometer
2. Size- depends upon the cell that one has fabricated. Usually the size of a pettry dish.
3. Thermal stability- found to be stable up to 500C. Stability may be increased up to 700C.
4. Recharging- Gets automatically recharged by the solution present in source and stripping
phase. In both acidic and alkaline pH.

23. Transport mechanism in PIM
Actual mechanism may be very complex., and
May depend upon
1. Physicochemical prosperities of the carrier.
2. Nature of target solute
3. Membrane composition
4. pH and the nature of source (feed) phase
5. pH and the nature of stripping phase.
6. Temperature
More research is needed to understand the intricate relationship between these factors

25. Some latest PIM reports
S.No. Polymer Carrier Plasticizer Target ions Reference
1 CTA D2EHPA 2-NPOE Pb2+, Cd2+, Zn2+ O.Kebiche et.al 2015
2 PVA B-CD none Phenol
exrtraction
Fadila oughlis et.al 2015
3 CTA CYPHOS IL-104 NPOE Cu2+, Mn2+,
Cd2+,
Beta pospieh 2015
4 CTA Calix [4]
Resorcinarene
derivatives
2-NPOE Zn2+ Ayes uger et.al, 2015
5 CTA Substituted DGA -2-NPOE Am3+,
Pu4+,UO2
2+,
Th2+
B.N. Mahanty et.al.2015

26. Some latest PIM reports
S.No. Polymer Carrier Plasticizer Target ions Reference
6 CTA Cyphos IL 104 none Pd2+ Rosocka et.al. 2015
7 CTA Cyanex 471 X 0-NPOE Pd2+ Beata Pospiech et.al.
2015
8 CTA/PVC Cyphos IL-101
Cyphos IL-104
O-NPOE Zn2+ Monika Baczynska et.al,
2015
9 SLM/TOPO TOPO none Cr(VI) from
industrial
effluents
Robina Nawaz et.al. 2015
10 CTA 1-heptyl
imidazole and
other similar
derivatives
NPPE Cu2+, Zn2+,
Ni2+, Co2+
Elzbieta Radzyminska
et.al,2015

27. Can we plan for PIM research……
Yes, we can.
1. Identify or select a problem related to ion separation. Also refer to the review articles, particularly of 2006, and
2012 of S.D.Kolev, Journal of membrane science.
2. Think of making a membrane, membrane material, plasticizer (may, may not be) and a carrier. Carrier, available
commercially may be used, such as cyphos, cynax etc or think of new ligands that contain large hydrophobic part
and hydrophilic centres. Neutral macrocyclic crown ethers or non-cyclic oxo-crown ethers may be used.
3. After making a membrane, investigate membrane morphology. AFM (atomic force microscopy) or SEM
(scanning electron microscopy) may be used. Refer to the available lab. (you may not be an expert of the same.)
4. Fabricate a PIM cell, as demonstrated earlier. ( or your novel cell)
5. Select correct composition of feed phase and receiving Phase., to drive the flux to the receiving phase.
5. Cation analysis may be done by AAS or flame photometer, or spectrophotometer in case of coloured ions/
counter anions.

28. What is there to be studied…..
1. PIM morphology
2. Flux of cation across the membrane.
2. investigate the kinetics of flow of metal ion across the membrane.
4. See if it is a genuine carrier facilitated metal ion transport, or follows any defined kinetics.
5. investigate the selectivity of membrane, can it discriminate one over another ion?
6. investigate about the nature of stripping phase.( Receiving Phase.)
7. Investigate about working parameters such as pH and temperature.
8. Try to develop some mathematical models.
9. Publish your work in some standard Journal, “Journal of membrane science” for example.
and see that
This work can be delivered to the industry for bulk separation/ characterization, in broader
interest of science and society. Register for Patents.

29. Here we stand today…………..
And .. what is the
scope of PIM
experiments in
future?...
Commercial
applications and
as
electrochemical
sensors.

30. Future scope
It can be expected that future research will expand the number of
commercially available carriers, plasticizers as well as base
polymers that can be used.
It is not believed that PIM systems will replace traditional solvent extraction
systems, and certainly not in the near future, but will find a role in niche areas
such as amino acid separation in biotechnology, fructose enrichment in food
processing technology, precious metal recovery from electronic scrap and
catalytic converters, the treatment of radioactive waste streams and in
environmental clean up of contaminated waters.
S.D.Kolev

31. Thanks
Questions?