In-situ reduction of gold thiosulfate complex on molybdenum disulfide nanosheets for a highly-efficient recovery of gold from thiosulfate solutions

Abstract

Thiosulfate leaching is widely considered an alternative and nontoxic technique for cyanidation in gold hydrometallurgy; however, the main problem with this technique is the difficulty in recovering gold from pregnant solutions. Here, we report that a simple and accessible material, molybdenum disulfide nanosheets, can effectively in-situ reduce and recover gold from pregnant solution based on its semiconducting properties. The results of the in-situ reduction showed that the gold-thiosulfate complex([Au(S2O3)2]3−) can be reduced to elemental gold particles with a particle size of 130–320 nm. The origin of the in-situ reduction of gold might be derived from the photo generated electrons released by molybdenum disulfide. The 1866.762 mg∙g−1 recovery capacity of gold on molybdenum disulfide from a 100 mg∙L−1 initial gold solution, which is 1000 times the recovery capacity of modified activated carbon, further demonstrates that molybdenum disulfide is a superior gold recovery material. Moreover, the removal of ~99% gold from gold-loaded MoS2 indicates the recyclability of MoS2 in gold recovery. Based on these results, it is obvious that molybdenum disulfide nanosheets is an excellent material to recover gold from gold-thiosulfate complexes. Besides, the application of molybdenum disulfide to gold recovery can simplify the traditional thiosulfate leaching process.