Efficient Au(S2O3)23– recovery from S2O32- system through coupling electromigration and photocatalysis effect on defect introduced and oxygen incorporated MoS2

High concentration of S₂O₃^2- in gold thiosulfate leaching solution caused serious obstacle for Au(S₂O₃)₂^3– recovery because of the strongly competitive adsorption effect. To cope with this trouble, a novel recovery strategy of coupling electromigration and photocatalysis (CEP) by using MoS₂ cathode electrode and activated carbon (AC) anode electrode pairs has been proposed in this work. Au(S₂O₃)₂^3– recovery behavior and recovery mechanism by CEP were detailed investigated with specific voltage and indoor light irradiation. Under the condition with S₂O₃^2-/Au(S₂O₃)₂^3– molar ratio of 2000:1, ∼98 % gold recovery performance achieved. In addition, modified MoS₂ with defect introducing and oxygen incorporation (D,O-MoS₂) could greatly enhance gold recovery performance because of more excellent photoelectric property for faster Au(S₂O₃)₂^3– reduction. Besides, the influences of CEP parameters such as voltage, water flux and electrode pairs were systematically explored for better understanding of gold recovery behaviors. Confirming by characterization tests and COMSOL simulation, the movement of S₂O₃^2- was mainly controlled by electromigration to move towards anode and then stored in the electric double layer (EDL) of coated AC. Meanwhile, Au(S₂O₃)₂^3– was impelled to diffuse towards cathode driven by its concentration gradient and then reduced to Au⁰ through photogenerated electrons from coated D,O-MoS₂. Therefore, by means of distinct mass transfer behaviors, Au(S₂O₃)₂^3– could separate from high concentrated S₂O₃^2- system, so that achieving satisfied recovery performance via excellent photocatalytic reduction effect from D,O-MoS₂. These findings provided a new insight for enhancing Au(S₂O₃)₂^3– recovery from gold thiosulfate leaching solution, which catered to the topic of green production of gold.