Electroseparation of cobalt and nickel from a simulated wastewater

Abstract

A study of the electrodeposition at sheet electrodes was carried out under potentiostatic control for solutions containing either 0.1 m Co(ii) or 0.1 m Ni(ii) and a 1:1 mixture of both 0.1 m Co(ii) and 0.1 m Ni(ii). From the linear sweep voltammetry of solutions containing only either Co(ii) or Ni(ii), a potential region in which cobalt would be expected to be electrodeposited without the simultaneous electrodeposition of nickel was identified and a theoretical deposit composition against potential plot was constructed. Deposition from a 1:1 Ni(ii): Co(ii) mixture at the optimum potential for separation produced a 90% cobalt /10% Ni alloy. Long term, potentio-selective extraction from a 1:1 Ni(ii): Co(ii) mixture showed that when the stainless steel cathode was predeposited with pure cobalt, the cobalt level in the solution could be reduced to less than 5% of its original value whilst leaving the Ni(ii) at 85% of its original value.