Selective transport of zinc as Zn(SCN)(4)(2-) ion through a supported liquid membrane using K+-dicyclohexyl-18-crown-6 as carrier

A new supported liquid membrane (SLM) system for the selective transport of zinc ion is described. The SLM used is a thin porous polyvinyldifluride me mbrane impregnated with dicyclohexyl-18-crown-6 dissolved in nitrophenyloct yl ether. Potassium-dicyclohexyl-18-crown-6 acts as a highly efficient carr ier for the uphill transport of zinc as Zn(SCN)(4)(2-) through the SLM. In the presence of L-Cysteine as a metal ion acceptor in the strip solution, t ransport of zinc occurs almost quantitatively after 5 h. The selectivity an d efficiency of zinc transport from aqueous solution containing different m ixtures of Co2+, Ni2+ Cu2+, Pb2+, Cd2+, Hg2+, Fe3+ and Cr3+ ions were inves tigated. In the presence of citrate ion and thiourea as suitable masking ag ents in the feed solution, the interfering effects of Pb2+ and Cu2+ ions we re completely eliminated. (C)2000 Elsevier Science B.V. All rights reserved .