Effect of surfactants on the kinetics of nickel(II) extraction by 2-hydroxy-5-nonylacetophenone oxime (LIX 84) in an n-heptane/water system

Abstract

The initial reaction rates of the extraction of nickel(II) by 2-hydroxy-5-nonylacetophenone oxime (HNAPO) in a two-phase oil/water system was measured using a total internal reflectance static transfer cell. A two-step reaction mechanism between nickel(II) and HNAPO was found to satisfactorily explain the observed initial reaction rate (Rint). The addition of neutral surfactants, nonionic octaethylene glycol mono-n-dodecyl ether and zwitterionic n-dodecyldimethyl-3-ammonio-1-propanesulfonate, decreased R int, which could be accounted for with a competitive surface adsorption model. The presence of the anionic surfactant sodium dodecyl sulfate accelerated and then decelerated Rint, while the ..