Optimization of Electrowinning of Cobalt using Central Composite Design for the production of Pure Cobalt Metals from Chloride Solution
Materials and Nuclear Fuel Research School, Nuclear Science and Technology Research Institute, P.O. Box 11365-8486, Tehran, Iran
The electrowinnig conditions for the production of the pure cobalt metal from chloride aqueous solution were studied. The effects of four parameters such as the acidity of feed solution (pH), cobalt ion concentration in the feed phase, reaction time as well as current ampere were investigated by using central composite design which is a subcategory of response surface methodology. The optimum conditions obtained for pH, cobalt ion concentration, time, and current ampere were 4, 0.008 mol/L, 40 min and 1 A, respectively. In addition, the high current efficiency can be achieved at relatively low temperature. It is found that the presence of Cl- has no significant effect on cathode potential, current efficiency and crystal orientations. The effect of additives and impurities were investigated, and it was shown that nickel does affect cobalt deposition, but only when it is present in high concentrations (>0.01 mg/L). The surface morphology of the electrodeposited cobalt obtained from pure cobalt sulfate solution was smooth and compact and consisted of fibrous crystallites with 99.96% purity.