Selective separation of copper and nickel ions from aqueous solutions containing calcium by emulsion liquid membranes using central composite design

Abstract

AbstractThe emulsion liquid membrane technique was utilized to selectively extract copper and nickel from a synthetic aqueous solution containing calcium, which was used to mimic a tailings stream found in the Sudbury region of Canada. The results showed copper and nickel ions were successively extracted from the synthetic solution. Two central composite designs and an analysis of the experiments were used to optimize the process and determine the main effects and interactions of experimental factors. In the first stage, copper was extracted with a minimum removal of nickel and calcium. It was found that under optimum conditions 98 % of the copper was extracted, with only 0.9 % of the nickel and 1.3 % of the calcium being extracted. The subsequent copper stripping efficiency was 95.7 %. In the second stage, the remaining aqueous solution was treated to remove nickel with minimum calcium removal. During this stage, the corresponding nickel and calcium removal percentages were 99.0 and 0.55 %, respectively, with a nickel stripping efficiency of 84.1 %. Laboratory bench‐scale tests using a two‐stage mixer‐settler showed a good correlation with these results when moving to a semi‐continuous process, which extracted 99.7 % of the copper and 98.2 % of the nickel, with only 2.2 % calcium extraction.