Selective electrodeposition of metals from simulated waste solutions

Most industrial waste streams contain a number of different heavy metals. The feasibility of selective electrodeposition of cadmium, cobalt and nickel as their pure metals (similar to 99%) from binary mixtures has been investigated. Single cation linear sweep voltamograms and nucleation potential measurements have been made and used to predict the optimum potentials and conditions for selective electro-deposition from the mixed-cation solutions. The anions used in this work are SO42-, Cl- and BF4-. The optimum potential for removal by electrodeposition of Cd from a solution containing Cd(II) and Co(II) or Ni(II) without codepositing Co or Ni has been evaluated from a simple diagram constructed from nucleation potential measurements. It is shown that the [Cd(II)] remaining in the solution after exhaustive electrolysis at a fixed potential is determined by the Nernst equation, and not by the electrolysis time provided that. a critical minimum time has been exceeded.