Kinetics and the effect of electrostatic surface potential on nickel(II) extraction by 2-hydroxy-5-nonylacetophenone oxime (LIX 84) in a micellar phase

摘要

The kinetics of extraction and the effect of electrostatic surface potential on the nickel(II)/2-hydroxy-5-nonylacetophenone oxime (HNAPO) extraction system were characterised in a non-ionic micellar system. A two step reaction mechanism between nickel(II) and HNAPO was found to satisfactorily explain the observed kinetics. Simulation of the kinetics of the complexation reaction over a wide range of concentrations provided the rate constants for the proposed mechanism. The addition of a cationic surfactant, dodecyl trimethyl ammonium chloride (DTAC), slowed the reaction kinetics. while the inclusion of an anionic surfactant, sodium dodecyl sulphate (SDS), enhanced the reaction kinetics relative to the non-ionic micellar system. The charge effects on the reaction rate could be successfully modelled based on the electrostatic surface potential generated by the anionic and cationic surfactants. (C) 2004 Elsevier B.V. All rights reserved.