Structure-tailored poly(ionic liquid)s for recovery of gold from thiosulfate system

Two types of poly(ionic liquids) (PILs), namely linear PILs (LPILs) and reticulated cross-linked network PILs (RPILs), were synthesized and evaluated for the adsorption of gold thiosulfate complex ([Au(S 2 O 3 ) 2 ] 3− ) from thiosulfate solutions. Experimental results showed that the adsorption of [Au(S 2 O 3 ) 2 ] 3− on the PILs followed the pseudo-second-order kinetic model, indicating that the adsorption process was dominated by chemical adsorption. In terms of adsorption thermodynamics, the bromide-based LPIL fitted the Hill adsorption model, whereas the other PILs followed to the Freundlich model. The main interactions between the PILs and [Au(S 2 O 3 ) 2 ] 3− were electrostatic attraction and anion – π interactions, and ion exchange dominated the gold adsorption process. The RPILs exhibited higher gold adsorption capacities than the LPILs. However, gold desorption was more readily achieved with LPILs, primarily owing to their weaker affinity for gold species. In addition, the perchlorate-based LPIL showed good adsorption selectivity and recyclability toward [Au(S 2 O 3 ) 2 ] 3− . This study provides a promising strategy for the efficient separation and recovery of gold from thiosulfate media.