Bicentric Poly(ionic Liquid)s Adsorbent for Gold, Palladium, and Platinum Recovery in Acidic Medium

Precious metal recovery from secondary resources with high efficiency and minimal environmental impact remains a critical challenge in separation technology. In this study, a novel ionic liquid N6-tetramethyl-N1-(4-vinylbenzyl)hexane-1,6-diammonium chloride (TVBHDCCl₂) was synthesized and subsequently polymerized into bicentric poly(ionic liquid)s, designated as P(TVBHDCCl₂)s. The P(TVBHDCCl₂)s demonstrated exceptional adsorption capacities for gold (637 mg/g), palladium (299 mg/g) and platinum (542 mg/g) with fast adsorption kinetics to reach equilibrium within 2-4 min and appreciable stability in acidic medium (pH = 1). Combined experimental and theoretical analyses revealed that the adsorption process is governed by a synergistic mechanism involving electrostatic interactions and redox reactions, with the primary adsorption site located in the region between the double cationic center in P(TVBHDCCl₂)s. In summary, this work introduces a highly efficient, selective, and sustainable polymeric adsorbent for simultaneously recovering precious metals from secondary resources, presenting a viable strategy for resource recycling and green separation technology.