Selective removal of copper and nickel ions from synthetic process water using predispersed solvent extraction

Abstract

AbstractSelective predispersed solvent extraction and the stripping of copper and nickel ions from synthetic process water containing calcium ions was investigated, and the effect of four experimental parameters on extraction efficiency was studied. The extraction process was performed in two stages. In the first stage, maximum copper extraction was targeted with nickel extraction minimized. During the second stage, nickel was extracted from the remaining copper‐free aqueous solution and optimum experimental conditions for maximum nickel recovery were determined. In order to investigate the effect of experimental parameters (extractant concentration, phase volume ratio (PVR), equilibrium pH, and calcium concentration) on the nickel extraction, response surface methodology (RSM) was used. It was found that equilibrium pH, extractant concentration, and calcium concentration were the most significant factors on nickel extraction. While the first two factors had a positive effect, the latter one negatively affected the response. In order to selectively extract copper, the optimum range for the maximum extraction of copper with minimum nickel extraction was determined, which for any level of calcium concentration is an extractant concentration of 0.2–0.3 % (w/v), phase volume ratio of 2, and equilibrium pH of 2.5. Once copper ions were selectively removed from the process water, the optimum conditions for maximum nickel concentration were determined at three levels of calcium concentrations. Stripping experiments were also carried out, and the optimum acid concentrations of 10 and 5 g/L were determined for the stripping of copper and nickel, respectively.