Application of cationic membrane electrolysis on the recovery of copper from thiosulfate solutions

Abstract

Due to the instability of thiosulfate ions (S2O32−), the recovery of metals from thiosulfate solution using direct electrodeposition has not been widely adopted yet. In the current work, the cationic membrane electrolysis (CME) equipped with cationic membrane was employed for the copper recovery from thiosulfate solution. The effect of operational parameters such as pH and ionic strength of anodic compartment, electrode distance, cell voltage and electrolysis temperature on the copper stripping were investigated systematically, and the duration of cationic membrane was considered subsequently. The result indicated that the pH of anodic compartment played a decisive role in the electrolysis process, i.e. high pH value (>14.0) promoted OH− ions penetration, while low pH (<13.0) easily generated H+ and passed through cationic membrane leading to the dissociation of S2O32−. At optimal experimental conditions, the recovery efficiency of copper reached more than 99%, with energy consumption of 1.58 W h/g Cu, while less than 0.3% of S2O32− was decomposed which was consistent with IR analysis of electrolytic solution. Besides, the cationic membrane used in electrolysis process reached 10 times and easily regenerated. This work provided an effective green and economic approach to recover copper from thiosulfate solution, and then avoid the decomposition of S2O32− using electrolysis process.