Membrane Transport of Pb(II) with a Cooperative Carrier Composed of Dibenzyldiaza-18-crown-6 and Palmitic Acid

A chloroform membrane system containing a given mixture of dibenzyldiaza-18-crown-6 and palmetic acid was applied for transport of Pb2+ ions. The transport was capable of moving metal ions "up-hill". Thus, it was possible to follow the transfer of Pb(II) from the aqueous source phase to the organic layer and from the organic layer to the receiving phase. The effects of thiosulfate concentration in the receiving phase, palmetic acid and dibenzyldiaza-18-crown-6 concentration in the organic phase on the efficiency of the transport system were examined. By using S2O32- ion as metal ion acceptor in the receiving phase, the amount of lead ion transport across the liquid membrane after 150 minutes is 96 +/- 1.5%. The selectivity and efficiency of lead transport from aqueous solution containing Cu2+, Tl+, Ag+, Co2+, Ni2+, Mg2+, Zn2+, Hg2+, Cd2+, Ca2+ were investigated. In the presence of thiosulfate as a suitable masking agent in the source phase, the interfering effects of Ag+ and Cu2+ were diminished drastically.