Active facilitated transport and separation of Co in Co-Ni sulfate solution by hollow fiber supported liquid membrane containing HEH(EHP)

The active facilitated transport and separation of cobalt in mixed solution of cobalt and nickel sulfate were studied using hollow-fiber supported liquid membrane (HF-SLM). The HF-SLM contained 2-ethylhexyl-phosphonic acid mono-2 ethylhexyl ester [HEH(EHP)], which was diluted in kerosene as a carrier. The permeation rates and separation factors were found to be dependent on the operational variables such as the concentrations of metal and hydrogen ions in the feed solution, the carrier concentration in the liquid membrane, and the flow rate of feed solution. The permeation rate of cobalt was 10(-6)-10(-7) mol/m(2) s and the separation factor of Co/Ni was 10-220 under the experimental conditions. By recirculating the strip solution, a tenfold enrichment of cobalt was possible and cobalt with 95% purity was recovered from the low concentration solution in which the concentrations of both cobalt and nickel were 17 mol/m(3).