Tailoring Selectivity in Redox-Copolymers for the Electrochemical Recovery of Platinum Group Metals from Complex...

Platinum group metals (PGMs) are essential for growing energy applications, and with declining ore grades and the complexity of feedstocks, efficient separation processes for PGM recovery and purification are needed. Redox-copolymer electrosorbents were developed for the selective recovery of PGM chloroanions from ores processed via flotation and leaching, as well as catalytic converters. An electrosorbent integrating a ferrocene redox moiety and a metal-affinity ligand achieved a separation factor >20 between palladium and platinum. Electrochemically assisted regeneration enhanced the release efficiency by >90% compared to a solely pH-driven ligand deprotonation. Thus, the combination of electrochemical stimulus with pH swings can reduce the overall load of chemical input when compared to a solely chemical regeneration. The redox-copolymer retained 90% of uptake capacity after over 300 cycles and demonstrated improved stability over the redox-homopolymer. Unlike processes that may require pH adjustment or alkaline precipitation, our approach achieves PGM uptake directly from highly acidic (pH ∼1) leachates from both ores and catalytic converters in the presence of excess transition metals and competing inorganic ions in solutions. A technoeconomic analysis demonstrated that Pt recovery becomes economically viable after only nine regeneration cycles, highlighting the cost-efficiency of the process. This work highlights redox-copolymers as a promising platform for metal recovery from complex feedstocks, with tunable selectivity, robustness, and regeneration.