SYNERGISTIC SOLVENT EXTRACTION OF Co(II), Ni(II), Cu(II) AND Zn(II) BASED ON SUPRAMOLECULAR ASSEMBLIES

摘要

The aim of the studies now reported was to investigate synergistic extraction of Co(II), Ni(II), Cu(II) and Zn(II) with a mixed ligand system consisting of a macrocyclic amine and an organic acid. A key design feature of such mixed extractant systems is their ability to form supramolecular assemblies which are preorganized for metal complexation and which are able to reversibly transfer metal cations from an aqueous feed solution. Experiments were performed to elucidate the inter-dependence of the extraction behaviour on the metal ion type, the nature of the diluent as well as the concentration ratio of both extractants, and the pH of the aqueous solution. Furthermore, an NMR titration study of assembly formation in solution and an X-ray structure of a relevant crystallized ligand adduct have been obtained in order to aid understanding of the observed solvent extraction results.