Selective Transport of Copper(I,II), Cadmium(II), and Zinc(II) Ions through a Supported Liquid Membrane Containing Bathocuproine,Neocuproine, or Bathophenanthroline

Abstract

Some selective transport systems for heavy metallic ions through a supported liquid membrane (SLM) containing a 2,2′-dipyridyl derivative ligand, 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine), 2,9-dimethyl-1,10-phenanthro-line (neocuproine), or 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline), were investigated. The transport of copper(I, II), cadmium(II), zinc(II), lead(II), and cobalt(II) ions was accomplished with a halogen ion such as chloride, bromide, or iodide ion as a pairing ion species for any SLM. The ranking of the permeability of the metallic ions was Cu^+,2+, Zn²⁺, Cd²⁺ ? Pb²⁺, Co²⁺. When the oxidation-reduction potential gradient was used as a driving force for metallic ions, the transport of Cu⁺ ion was higher than those of Cd²⁺ and Zn²⁺ ions for any SLM containing bathocuproine, neocuproine, or bathophenanthroline. On the other hand, in the transport system which used the concentration gradient of pairing ion species, the permeability of the Cu²⁺ ion decreased whereas that of the Cd²⁺ ion increased. Moreover, it was found that the different selectivity for the transport of metallic ions is produced by using various pairing ion species.