A novel sandwich supported liquid membrane system for simultaneous separation of copper, nickel and cobalt in ammoniacal solution

In this paper, a new strategy based on a supported liquid membrane (SLM) system for the simultaneous and selective separation of copper, cobalt, and nickel in ammonia/ammonium chloride solutions, using a two-membrane-three-compartment cell (sandwich SLM) was proposed. This model used two polyvinylidene difluoride (PVDF) membranes both loaded with 20 vol.% Acorga M5640 in kerosene. The effects of H2SO4 concentrations in two stripping phases on the transport of copper, nickel, and cobalt were evaluated. Experimental results indicated that copper and nickel were transported through the first membrane into the central compartment which contained 5.0 g/L H2SO4, while cobalt remained in the first feed compartment. Then copper continued to penetrate through the second membrane into the third compartment which contained 50.0 g/L H2SO4, while nickel remained in the second compartment. More than 99.5% of cobalt, 98.0% of nickel, and 98.9% of copper were separated into the three different compartments from a mixed feed solution containing 100 mg/L each of these three species with a transport time of 36 h. A maximum copper flux of 1.59 × 10−6 mol/m2·s was obtained. The results establish that copper, nickel, and cobalt in ammonia solution can be efficiently separated by this novel type of sandwich SLM.