PERMEATION RATE AND SELECTIVITY IN THE SEPARATION OF COBALT AND NICKEL BY SUPPORTED LIQUID MEMBRANES

Abstract

The transport of cobalt and nickel from nitrate solutions through supported liquid membranes (SLM) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester dissolved in n-dodecanc as a carrier was studied. High selectivity in the separation of cobalt and nickel was obtained when the diffusional resistance in the liquid membrane was dominant. Experiments on the extraction of cobalt and/or nickel were also carried out over a wide range of metal loading ratio, and empirical correlations representing the concentrations of the aggregated species in organic phase were presented. Using a permeation model in which the formation of aggregates of metal-carrier complexes was considered, the fluxes in single and simultaneous permeations were quantitatively explained.