Rapid recovery of precious metals via photocatalytic-assisted solvometallurgy using an ethylene glycol-based solvent

Abstract

Precious metals are critical to electronics and catalysis because of exceptional conductivity, corrosion resistance, and unique physicochemical properties. However, the surge in demand driven by the expansion of the electronics and automotive industries has intensified the environmental and economic pressures associated with the accumulation of precious metal waste. Photocatalysis has emerged as a promising strategy for resource recovery; however, its dependence on toxic acetonitrile solvents limits industrial applicability. Here, we present a photocatalytic-assisted solvometallurgical approach employing ethylene glycol—a benign, low-volatility solvent—to achieve complete leaching of precious metals from various industrial waste catalysts within 10 min. Field-scale experiments conducted under solar irradiation processed 125 g of spent catalyst in a single batch, yielding 0.45 g of high-purity palladium (>99%). This approach expands the solvent scope for photocatalysis, eliminates the need for hazardous reagents, and facilitates solar-powered operation, thereby offering a practical and scalable pathway for sustainable precious metal recycling.