Selective and fast recovery of Au(I) from thiosulfate gold leaching solution: the role of aromatic adsorbents
A key challenge in the recovery of Au ions from thiosulfate gold leaching solutions is the design of adsorbents with abundant active adsorption sites, exhibiting high affinity and selectivity toward Au(I), thus enabling its fast, high-purity, and large-capacity recovery. Guided by theoretical calculations, in this study a polychloromethylstyrene (PCMS) material capable of supplying additional charges was functionalized by triethylamine (TEA) to selectively recover gold from a thiosulfate leaching solution. The adsorption of Au(S₂O₃)₂³⁻ onto the functionalized PCMS–TEA followed pseudo-second-order kinetics and was consistent with the Langmuir isotherm model, suggesting a single-molecular-layer chemisorption process. PCMS–TEA exhibited a significant Au-ion loading capacity (81.50 kg/t), highlighting the potential of benzene rings to enhance the charge intensity of ionic adsorbents. Furthermore, PCMS–TEA exhibited good Au-ion selectivity in a copper–ethylenediamine–thiosulfate Au leaching solution. The adsorption mechanism of Au ions on PCMS–TEA involved ion exchange between Cl − in the adsorbent and Au(S 2 O 3 ) 2 3− complex ions. The visual analysis of density functional theory results, based on the Multiwfn and Visual Molecular Dynamics programs, confirmed the presence of a weak interaction between PCMS–TEA and Au(S 2 O 3 ) 2 3− , dominated by van der Waals forces. After five desorption cycles, the adsorption rate of Au ions was approximately 90%, and NaCl was used as the elution reagent. This study introduces a promising adsorbent for the selective recovery of Au ions from thiosulfate Au leaching solutions.
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