Precious metals (gold, silver, platinum, palladium, rhodium, etc.) are widely used in automotive, electronics, pharmaceutical, and jewelry industries due to their exceptional corrosion resistance, high-temperature stability, and catalytic properties. Given their limited natural reserves and concentrated distribution, primary ore mining incurs high costs and significant environmental impacts. Consequently, extraction and recovery from secondary resources have become the mainstream trend in the industry. These secondary resources include spent automotive catalysts, electronic waste (WEEE), electroplating rinse wastewater, and precious metal smelting residues. Characterized by complex compositions and low precious metal concentrations, traditional extraction methods (such as chemical precipitation and solvent extraction) suffer from low separation efficiency, insufficient purity, and severe pollution issues. Ion exchange resins, with their high selectivity, ease of regeneration, and environmentally friendly efficiency, have emerged as the core technological solution for precious metal extraction and recovery.

Ion exchange resins undergo selective ion exchange or adsorption reactions with precious metal ions or their complexes in solution through specific functional groups (such as chelating groups or quaternary ammonium groups) on their polymeric backbone. For instance, gold exists as a complexed anion in electroplating wastewater, where strongly basic anion exchange resins achieve efficient adsorption through chloride ion displacement. Platinum and palladium form stable complexes in chloride solutions, enabling targeted capture by anion exchange resins. Rhodium can be separated from other platinum group metals using specialized resins by adjusting solution pH to neutrality. The adsorbed resin is treated with an eluent to desorb the precious metal ions, enabling resource recovery and resin regeneration.