A Method of Recovery Au(I) from Thiosulfate Solution by Novel Functionalised Activated Carbon

Abstract Effective gold recovery from thiosulfate leaching solution is important for the development of non-cyanide gold leaching technology. Herein, a novel functionalised activated carbon (denoted as AC-SH) that can effectively adsorb Au(I) from thiosulfate solution was synthesised using an environment-friendly route via the solid-phase reaction of activated carbon with 2-mercaptobenzoxazole. In the batch experiments, the effects of contact time, solution pH, temperature, and initial Au(I) concentration on the adsorption performance of AC-SH were investigated. Langmuir isotherm and pseudo-second-order kinetic models suitably described the adsorption of Au(I). Additionally, FT-IR, SEM, EDS, and XPS data revealed that AC-SH was successfully synthesised and Au(I) adsorption on AC-SH proceeded through chelation with Au(I) via the S‑containing functional group. The BET analysis result of AC shows that it is a mesoporous material (average pore diameter 2.193 nm). Additionally, Au-loaded AC-SH could be substantially desorbed (>95% recovery) using a concentrated thiosulfate solution. Herein, an economical, simple, and easy-to-implement method for the effective recovery of Au(I) from thiosulfate solution is described, which is expected to advance the development and application of non-cyanide Au extraction technology.