Removal of Cadmium from Cobalt Sulfate by Solvent Extraction Using Cyanex 301

A variety of reagents, including P204, P507, and Cyanex 301, were used for extraction of cobalt and cadmium from cobalt sulfate solution. It was found that Cyanex 301 exhibited the best separation efficiency for cadmium and cobalt from solution containing 90 g L−1 Co and 3 g L−1. The effects of initial pH, extractant concentration, phase ratio, extraction time, and temperature on the cadmium and cobalt extraction ratios were examined. The results showed that the extraction ratios of cadmium and cobalt were 99.95% and 2.45% under the optimal conditions of pH 1.8, 10% Cyanex 301, O/A = 1:1, T = 25°C, and t = 10 min. The species of Cyanex 301 chelated with cadmium or cobalt were proposed to be Cd[Cyanex 301]2.5 and Co[Cyanex 301]2. The stripping ratios of cadmium and cobalt were 99.9% and 95% using 7 mol L−1 hydrochloric acid, respectively, indicating effective separation of cadmium from high-concentration cobalt sulfate solution.