TRANSITION-METAL COMPLEXES WITH 8-HYDROXYQUINOLINE AND KELEX-100 IN MICELLAR SYSTEMS - STOICHIOMETRY OF THE COMPLEXES AND KINETICS OF DISSOCIATION IN ACID-MEDIA

Complexation of metal ions by micelle-solubilized extractants can be u sed for the development of new extraction processes. Metal extraction in micellar systems is in many respects analogous to solvent extractio n if one considers the use of ultrafiltration as a means to separate t he micellar pseudophase from the continuous aqueous phase. The present paper is intended to further characterize the nature of the complexes obtained in micellar systems (especially their stoichiometry and thei r stability as a function of pH) and to compare the results with those previously obtained in classical biphasic systems. The extractant mol ecules considered in this work were 8-hydroxyquinoline (HQ) and its al kylated analogue (C-11-HQ) derived from Kelex 100. Their complexes wit h Ni2+, CO2+, and Cu2+ have been investigated in micellar solutions ma de of cetyltrimethylammonium bromide (CTAB), 1-butanol, and water. The stoichiometry of the complexes was determined using Job's continuous variation method, and their kinetics of dissociation was investigated with the stopped-flow technique. Practical selective recovery of the d ifferent metal ions from their complexes in micelles was shown to be p ossible using ultrafiltration.