Electrochemically Mediated Recovery and Purification of Gold for Sustainable Mining and Electronic Waste Recycling

Rapid growth of the industrial and electronics sectors has led to an ever-mounting demand for gold. Gold mining can be highly resource-intensive, due to the need for selective gold separations from dilute streams, in the presence of multi-component metallic species. The development of efficient gold separation technologies is critical to mitigate the declining gold purity in mined ores and to meet the need for electronic waste recycling. We propose a modular electrochemical separation platform via metallopolymer-functionalized electrodes to selec-tively recover and concentrate gold from electronic waste and simulated mining streams. Polyvinylferrocene (PVF) redox-electrodes captured cyano-gold with 10-fold higher uptake (>200 mg/g) than conventional activated carbon and, importantly, demonstrated an exceptional separation factor >20 for gold vs competing metals in mining and electronic waste, including silver, copper, nickel, and iron. Rapid gold uptake was observed within 5 min, and electrochemically mediated release and concentration achieved a remarkable up-concentration ratio of 20:1. Electrochemical recycling of gold from real-world electronic waste (e.g., RAM boards) highlighted our system as a drop-in replacement for activated carbon sorbent, with a recovery efficiency 99% and superior technoeconomics, leading to a 94% cost reduction and over 90% final gold purity. Redox-mediated electrochemical separations can be a promising avenue for the energy-efficient, sustainable, and process-intensified gold recovery and recycling.

Automated summary

The rapid growth of the industrial and electronics sectors has caused a higher demand for gold. Efficient gold separation technologies are crucial to maintain gold purity in mined ores and meet the need for electronic waste recycling. A modular electrochemical separation platform using metallopolymer-functionalized electrodes was proposed to selectively recover and concentrate gold from electronic waste and simulated mining streams. The platform demonstrated high uptake of cyano-gold and exceptional separation factor for gold vs other metals, rapid gold uptake, and electrochemically mediated release and concentration.