Efficient gold recovery from low concentrated Au(S2O3)23− solution through enhanced photocatalysis via photothermal and surface plasmon resonance assistance on MoS2/MXene/Ag

Abstract

Thiosulfate technique is the most promising method to recover gold from electronic waste (e-waste) and natural ores due to its non-toxicity and high leaching efficiency. However, the bad affinity between Au(S2O3)23− and traditional adsorbents leads to unsatisfied gold recovery performance from leaching solution. In this work, highly efficient recovery of gold from low concentrated Au(S2O3)23− solution was achieved through enhanced photocatalysis process on a novel MoS2/MXene/Ag adsorbent. During recovery procedure, Au(S2O3)23− was in-situ reduced to Au0 by photogenerated electrons and then anchored on MoS2/MXene/Ag. Under Au(S2O3)23− concentration <10 ppm, over 99 % gold recovery performance could achieve within 2 h. Experimental tests have proved that MXene made fully use of near infrared (NIR) light energy to exhibit better photothermal effect, and surface plasmon resonance (SPR) effect of Ag can simultaneously facilitate the separation of electron-hole pairs on MoS2. By means of external temperature input and rapid charge carrier transmission, plenty of electrons were excited from MoS2/MXene/Ag for Au(S2O3)23− recovery. This work paved a pathway for efficient Au(S2O3)23− recovery, which catered to the demand for green production of gold in the future.