title: 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 (R(int)). 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 R(int), while the cationic surfactant dodecyltrimethylammonium chloride caused a decrease. The effects of these charged surfactants were accounted for using a combination of a competitive surface adsorption model and the Boltzmann distribution of charged species.
authors.affiliation: Particulate Fluids Processing Centre, Department of Chemical and Biomolecular Engineering, The University of Melbourne, Melbourne, Victoria 3010, Australia. dallas.warren@vcp.monash.edu.au
authors.forename: Dallas B
authors.initials: DB
authors.lastname: Warren
authors.forename: Franz
authors.initials: F
authors.lastname: Grieser
authors.forename: Jilska M
authors.initials: JM
authors.lastname: Perera
authors.forename: Geoff W
authors.initials: GW
authors.lastname: Stevens