Electrochemical Recovery and Concentration of Noble Metals

Abstract

Noble metals are integral materials to chemical and electronics industries for their unmatched chemical inertness, electrical conductivity, and catalytic activity. However, the growing demand for noble metals such as Pt, Pd, and Au is outpacing the dwindling supply, and without new recycle strategies these critical noble metal resources will run out. Therefore, energy and resource efficient noble metal recycling technologies are critical to develop sustainable use of these scarce and valuable resources. Recently, electrification of chemical process units has been receiving justifiable attention as an easily scalable means of increasing energy and material sustainability in industry, particularly for chemical separations. In particular, the incorporation of redox-active materials has been met with great success for chemical energy storage and chemical separations due to enhanced charge transfer and easily tunable target ion interactions. Here, we introduce an electrochemically mediated platform for capture, release, and up-concentration of noble metal complexes from mining ore, electronic waste, and valuable elements in industrial manufacturing, where favorable charge transfer binding of noble metals to electrode bound redox sites enables selective capture of target noble metals over other common competitors – all with the flick of a switch. Highlights of our system are its high uptake (>200 mg/g), selectivity (>5 vs competing ions), energy efficiency (<5 kJ/g-PGM), cyclability (>5000 reuse cycles), and scalability to flow system. Technoeconomic analysis of our system compared to current industrial separation technologies indicates economically significant improvements in capital and operating costs with our electrochemical noble metal recycling platform. By lowering the economic barrier of noble metal recycling, these critical materials can be sustainably used and reused for years to come.