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Transport studies were carried out for carbonate ions through supported liquid membrane (SLMs) by using Alamine 336 and trioctylphosphine oxide (TOPO) as carriers. Experimental variables were investigated, such as concentration of carbonate ion (10−5 to 4×10−2 M), carriers (10−5 to 10−1 M), and alkali (0.01–0.5); and stirring speed (50–150 rpm) of bulk solutions. The use of combined carriers Alamine 336 and TOPO shows a synergic transport of carbonate ions. The stability of the SLM system in relation to the transport of carbonate ions has been studied. The enrichment of carbonate ions (10−6 to 4×10−2 M) from the dilute solution was explored. The different combinations of amines with TOPO show synergic permeability of the carbonate ions through SLM system.

A novel idea of transport of yttrium (III) metal ions through fibers supported liquid membrane in two stage processes namely source to membrane and membrane to receiving phase has been proposed. The fibers supported liquid membrane was impregnated with different concentrations carrier. The experimental variables explored were concentration of yttrium (III) ions, pH of source phase, PC-88A concentration in membrane phase, acid concentration in receiving phase and stirring speed. The pre-concentration of yttrium (III) ions was investigated from the dilute solutions. The two-channel fibers supported liquid membrane solvent extraction was investigated for the transport of yttrium (III) ions from the source to membrane and membrane to receiving phase. The transport of yttrium (III) ions was observed through the fibers supported liquid membrane with capillary action.

Contained supported liquid membrane (CSLM) system has been explored for synergic liquid membranes. Different experimental variables such as concentration of acid, carrier, metal ion and complexing agents, stirring speed, etc. have been investigated. Trioctylamine (TOA) + tributyl phosphate (TBP) system has been explored for europium.

The studies on ion transport of terbium and dysprosium through a porous supported liquid membrane (SLM) containing TOPO (trioctyl phosphine oxide) and TBP (tributyl phosphate) as immobilised carriers have been carried out. The effect of stirring of bulk solutions on permeability coefficient has been investigated. The permeability coefficient increases with increase in pH of source phase from 0–6, and hydrogen ion concentration from 0.01 to 0.1 M of receiving solution. The dependency of permeability coefficient on the carrier concentration has been explored. The effect of ammonium thiocyanate concentration on permeability coefficient has been studied. In order to develop a method for enrichment of rare earth elements, further investigations were carried out by using a hollow fibre membrane extractor. The mechanism of ion transport of terbium and dysprosium in SLM systems has been explained.

Kinetic studies of yttrium recovery, consisting of extraction and stripping processes have made using 2-ethylhexyl-phosphonic acid mono-2-ethylhexyl ester (PC-88A, EHPNA) as an acidic extractant. The experimental variables affecting the ion transport flux of yttrium have been explored; that is, pH, carrier and stripping agent concentrations. Kinetic models for the extraction and stripping processes, including the complexation mechanism, are proposed.

Studies on the kinetics of neodymium transport through a bulk liquid membrane, in apparatus consisting of a source, membrane and receiving phases, have been carried out. Different experimental variables, such as the pH, carrier, metal ion and stripping agent concentrations, have been explored. However, the kinetic and solvent extraction methods were compared to determine the equilibrium extraction constant. Complexation mechanism models have been developed. The kinetic behaviour of the ion transport based on forward and backward extraction processes with the consideration of controlled parameters was predicted. The ion transport of neodymium in the receiving or membrane phase envisages the determination of forward and backward extraction rate constants.

The carrier-mediated transport of europium through a supported liquid membrane by immobilizing PC-88A (EHPNA) and Versatic 10 on a porous support has been investigated in order to explore its efficiency, effectiveness and utility. Europium from the source solution was transported in the pH range from 1 to 5.75 for EHPNA and 3 to 5.75 for Versatic 10 through a cellulose triacetate membrane towards a receiving solution of pH

The synergistic extraction behavior of thiocyanate complexes of gadolinium, dysprosium and erbium has been studied for a mixed system: M3+/NH4SCN/tributyl phosphate (TBP)+tricaprylmonomethylammonium chloride (Aliquat-336)+ xylene. The percentage extraction and distribution ratios were measured as a function of the pH as well as the NH4SCN, Aliquat-336 and TBP concentrations, respectively. The percentage extraction of gadolinium, dysprosium and erbium increases with increase in pH. It was significant in the pH range 4 to 6 in a thiocyanate media. The composition of a binary synergistic extracted complex of lanthanides into the organic phase is probably M(SCN)52-(L+)2•2TBPo under the conditions studied. The synergistic extraction sequence as a function of the atomic number of lanthanide elements is given.

Department of Chemistry, Indian Institute of Technology, Powai, Bombay-400 076 Cation exchange chromatographic behaviour of manganese(II) on Dowex 50W-X8 was studied in mixed solvent systems. Methanol, ethanol, 2-propanol, acetone, dioxane and tetrahydrofuran in conjunction with 2 M hydrochloric acid were used as eluanla Amongst the non-aqueous solvents tested, acetone, methanol and ethanol proved to be efficient while 2-propanol, dioxane and tetrahydrofuran had no practical utility. The separation of manganese from binary mixture containing alkali metals, alkaline earth metals and some other associated elements was carried out by the process gradientelution as Well as selective elution thing combinations of different organic solvents.Similarly, separation of multicomponent mixtures of six elements commonly associatedwith manganese was done by sequential separation in the mixed solvent system.