Efficient and Selective Recovery of Gold from Thiosulfate Leaching Solution Using Functionalized β‐Cyclodextrins Synthesized by a Steric Hindrance Strategy

Abstract

AbstractDesigning suitable adsorbents is a key challenge in the recovery of Au(I) from thiosulfate gold‐leaching solutions as the ideal adsorbent not only possesses abundant active sites with high affinities and selectivities toward Au(I), but also demonstrates fast recovery of Au(I) at high purity and large capacity. Herein, guided by theoretical calculations, a water‐insoluble inclusion complex is synthesized using β‐cyclodextrin (β‐CD) and diphenylphosphine (DPP) as host and guest molecules, respectively, by a steric hindrance strategy for highly efficient and selective Au(I) recovery. The prepared β‐CD@DPP exhibits outstanding Au(I) adsorption performance, with a saturated loading capacity of 146.28 mg g−1. The excellent adsorption performance of β‐CD@DPP for Au(I) is mainly attributed to the full exposure of the adsorption site and the weakly alkaline adsorption environment. Furthermore, β‐CD@DPP demonstrates outstanding selectivity for Au(I) in a Cu─NH3─thiosulfate gold‐leaching solution, and the Au(I) recovery rate is higher than 99%. Synthesis of β‐CD@DPP primarily depends on the weak interactions between DPP and β‐CD. Mechanism of adsorption of Au(I) on β‐CD@DPP involves ligand exchange between PPh2− and [Au(S2O3)2]3−. This study provides a new idea and material preparation method for highly efficient, selective, and large‐capacity recovery of Au(I) from thiosulfate leaching solution.