Highly efficient and selective membrane transport of silver(I) using hexathia-18-crown-6 as a specific ion carrier

Hexathia-18-crown-6 (HT18C6) was used as a specific ion carrier for the transport of silver ion through a chloroform bulk liquid membrane. In the presence of thiosulfate ion as a suitable stripping agent in the receiving phase, the amount of silver transported across the liquid membrane after 60 min is 99.5 +/- 1.0%. The selectivity of Ag+ transport from the aqueous solutions containing other Mn+ cations such as Tl+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Hg2+, and Cr3+ ions was investigated. Except with Hg2+ ion, non of the cations used Interfere the silver transport, even at a Mn+/Ag+ molar ratio of 500. The interfering effect of Hg2+ ion was successfully eliminated in the presence of EDTA at pH 5. (C) 2000 Elsevier Science B.V. All rights reserved.