Studies on the liquid membrane separation of metal cations using mobile carrier

Liquid membrane separation, which combines the solvent extraction and stripping processes in a single step, has been an area deserving special attention because of it great potential for low cost and energy saving. In this article, we reviewed our previous works on two kinds of liquid membranes: supported liquid membranes (SLM), immobilized on microporous polymeric membrane, and emulsifying liquid membranes (ELM) as a ( W/O)/ W emulsion. Transport of metal ions across SLM is formulated on the basis of mass-transfer processes including the interfacial chemical reaction. In addition, stabilities of both membranes of SLM and ELM are described, and the countermeasures for assuring the possible operating stability have been considered. Finally, the applications of SLM to the separation and concentration of cations were illustrated for aqueous solutions of some alkaline and heavy metal ions.