Leveraging Solvent Effects for Enhanced Oxidation and Coordination in Selective Piezocatalytic Gold Recovery from End-of-Life Electronics

Abstract

Efficient gold (Au) recovery from electronic waste (E-waste) under environmentally sustainable and mild conditions presents a significant challenge in resource recycling. This study introduced a novel piezocatalytic method for Au recovery from E-waste using a mixed acetonitrile–water (CH₃CN-H₂O) solution. The findings emphasize the crucial role of solvent effects in modulating catalytic performance, with a 75% CH₃CN solution offering the most efficient recovery. The solvent not only influenced the oxidation and coordination steps crucial for Au extraction but also facilitated electron and mass transfer, accelerating the generation of reactive species that promote Au dissolution. Furthermore, water amplified the effect of the solvent by modifying the chemical potential of surface species, thus optimizing catalytic reactivity. Under ultrasonic vibration, the piezocatalytic system achieved 100% Au recovery from various types of E-waste, exhibiting excellent adaptability across a broad pH range. Large-scale experiments at the kilogram level confirmed its practicality, with 100% recovery from printed circuit boards and 98% from central processing unit boards. This study underscores the importance of solvent effects in piezocatalysis and provides new insights into the sustainable recovery of precious metals, thereby paving the way for the design of solvent-assisted catalytic systems.