“…These are very exciting and useful methods for assessing the partitioning of metal ions into and out of the organic phase and are of special importance in separation science, medicine, water purification, and metallurgy (19,20). In recent years, we have introduced a variety of bulk liquid membrane systems for the selective and efficient transport of different transition and heavy metal ions including Cu 2ϩ (21,22), Zn 2ϩ (23,24), Hg 2ϩ (25), Pb 2ϩ (26,27), Cd 2ϩ (28), and Ag ϩ (29). In this article we report a new highly efficient and selective liquid membrane system containing potassium-dicyclohexyl-18-crown-6 for the uphill transport of palladium ion, as PdCl 4 2Ϫ counterion.…”