Activated alumina sphere-supported CdS-MoS2 heterojunctions: A high-performance catalyst for gold recovery

The efficient recovery of gold from thiosulfate leaching solutions remains challenging due to the low efficiency and operational complexity of existing methods. In this work, a cadmium sulfide-molybdenum disulfide heterojunction supported on alumina beads (CdS-MoS 2 @AS) was synthesized via a controlled hydrothermal strategy. The resulting composite was subsequently applied as a photocatalyst for the efficient recovery of trace thiosulfate gold (Au(S 2 O 3 ) 2 3- ) from thiosulfate systems. Structural and compositional analyses confirmed the successful formation of the CdS-MoS 2 heterojunction, which facilitated the separation and transport of photogenerated charge carriers. CdS-MoS 2 @AS achieved almost 100% gold recovery within 20 min, outperforming previously reported gold recovery materials. Even at ultralow gold concentrations (1–10 ppm), the photocatalyst maintained outstanding recovery efficiency, underscoring its potential for direct gold recovery from low-grade thiosulfate leachate streams. The enhanced recovery performance was attributed to the synergistic optical response of the CdS-MoS 2 heterojunction, which promoted rapid photogenerated electron transfer, thereby driving the effective reduction of Au(S 2 O 3 ) 2 3- to metallic Au 0 . This study presents an efficient and scalable strategy for gold recovery from thiosulfate solutions with great significance for the sustainable development of gold.