Competitive Bulk Liquid Membrane Transport of Heavy Metal Cations Using the 18-Crown-6 Ligand as an Ionophore

Competitive transport of Zn(II), Cd(II), Cr(III), Co(II), Ag(I), Pb(II), and Cu(II) cations from an aqueous source phase at pH 5 through bulk liquid membrane (BLM) containing 18-crown-6 (ion carrier), organic solvents chloroform, dichloromethane, 1,2-dichloroethane, and nitrobenzene, and chloroform-dichloromethane and chloroform-dichloroethane binary mixed solvents into an aqueous receiving phase at pH 3 has been investigated. The influence of the organic solvents and also the effect of some surfactants on the selectivity and transport efficiency of the metal cations through BLMs were studied. The obtained results show that the selectivity and the efficiency of transport for these heavy metal cations change with the nature of the organic solvents which were used as liquid membranes in these experiments. A good transport efficiency and high selectivity was observed for the Pb(II) cation under the experimental conditions in this investigation.