Precious metals (gold, silver, platinum, palladium, rhodium, etc.) are widely used in the automotive, electronics, pharmaceutical and jewelry industries due to their exceptional corrosion resistance, high temperature stability and catalytic properties. Given limited natural reserves and concentrated distribution, primary ore mining is associated with high costs and significant environmental impacts. Consequently, the extraction and recovery of secondary resources has become a major trend in the industry. These secondary resources include used automotive catalytic converters, waste electronic waste (WEEE), plating rinse wastewater, and precious metal smelting residues. Traditional extraction methods (such as chemical precipitation and solvent extraction), characterized by complex compositions and low concentrations of precious metals, suffer from low separation efficiency, poor purity, and serious contamination problems. Ion exchange resins, with their high selectivity, ease of regeneration and environmental friendliness, have become the main technological solution for the extraction and recovery of precious metals.

Ion exchange resins undergo selective ion exchange or adsorption reactions with precious metal ions or their complexes in solution through certain functional groups (such as chelating groups or quaternary ammonium groups) on their polymer backbone. For example, gold is present as a complexing anion in wastewater from electroplating industries, where highly basic anion exchange resins provide efficient adsorption by displacing chlorine ions. Platinum and palladium form stable complexes in chloride solutions, allowing targeted capture of anion exchange resins. Rhodium can be separated from other platinum group metals using special resins by keeping the pH of the solution neutral. The adsorbed resin is treated with an eluent to desorb precious metal ions, which allows the resource to be restored and the resin to be regenerated.