METAL EXTRACTION IN MICELLAR MEDIA - A COMPARISON OF COPPER COMPLEXATION RATES AND ULTRAFILTRATION YIELDS OF 2 ISOMERIC (E)-1-(2'-HYDROXY-5'-ALKYLPHENYL) 1-ALKANONE OXIMES

Copper(ll) complexing and extracting properties in micellar media of t wo isomeric hydroxyoximes differing in the location of their hydrophob ic alkyl chain [(E)-1-(2'-hydroxy-5'-nonylphenyl)-1-ethanone oxime (1) and (E)-1-(2'-hydroxy-5'-methylphenyl)-1-decanone oxime (2)] are comp ared. Stopped-flow kinetic measurements were conducted in cetyltrimeth ylammonium bromide (CTAB) and n-dodecyl hexa(ethylene glycol) ether (C (12)EO(6)) micelles and in methanol. The rates of complexation were ve ry similar in methanol, while complexation in micellar solutions at pH 5 was faster with 2 than with 1. The pH dependence of the observed ra te constants was consistent with a Hague-Eigen type mechanism. The pra ctical removal of copper from dilute aqueous solutions was investigate d using micellar extraction coupled with ultrafiltration. Close to 100 % removal was achieved with both surfactant systems at pH 6.2, with a ligand : metal ration of 5. Ligand 2 appeared to be slightly more effi cient than ligand 1. The effect of pH on extraction yield was studied in more detail with 1. The results of both the micellar extraction and kinetic studies have been discussed in relation to previous experimen ts involving classical extraction using water/xylene biphasic systems.