Electro reduction-recovery of Au(S2O3)23– within a low concentration range via multi-porous activated carbon electrodes

Low-concentration gold recovery from thiosulfate solutions (Au(S 2 O 3 ) 2 3– ) was vital for the application of thiosulfate leaching instead of traditional cyanide leaching in gold industries. Herein, electro reduction-recovery of gold in thiosulfate solutions via multi-porous activated carbon (AC) was proposed. Recovery of Au(S 2 O 3 ) 2 3– within a low concentration range by multi-porous AC electrodes reached to almost 100 %. Even in the presence of high concentration interferential ions (molar ratio of S 2 O 3 2− to Au was 300:1), there was not any effect on the recovery. Interestingly, Au(S 2 O 3 ) 2 3– was recovered on the surface of multi-porous AC electrodes as the form of gold metal, realizing the recovery and reduction at the same time, which would be prone to shorten the traditional recovery procedure. Besides, the correlation of Au(S 2 O 3 ) 2 3– adsorption behaviors and multi-porous AC structure was well studied. Appropriate activation temperature was beneficial for the generation of multi pores together with oxygen functional groups, providing rich activate sites for Au(S 2 O 3 ) 2 3– adsorption and reduction. High electric double layer capacity (EDLC) and low charge transfer resistance jointly affected the Au(S 2 O 3 ) 2 3– recovery ability. The work provided an approach for gold recovery within a low concentration range in thiosulfate leaching solutions using multi-porous AC electrodes, thus to promote the green development of gold resources.