Multi-metal electrochemical response mechanism for direct copper recovery from waste printed circuit boards via sulfate- and chloride-system electrolysis

Metal recycling from waste printed circuit boards (WPCBs) is crucial for resource sustainability. Electrolysis is promising in simplifying processes, improving recycling efficiency, and reducing consumption, while full knowledge on multi metal fate and response mechanism is indispensable for processing complex metals (Cu-Fe-Sn-Pb-Ni-Ag-Au) from WPCBs. Here, we studied multi metal responses in sulfate- and chloride-system electrolysis and realized direct copper recovery from WPCBs. Owing to ligand effects on metal redox potential , coordinates stability, and reaction kinetics, chloride system saves half energy by shifting Cu 2+ /Cu to Cu + /Cu, holds stable ionic lead and tin species, poses high silver loss, and produces cathode of higher surface quality. Both systems directly upgrade copper from 86% to ∼99.9% with detailed reaction pictures constructed. More environmental benefits are revealed through environmental impact comparison. The role of electrolysis for metal recycling from WPCBs were further discussed, being an important “hub” for efficient multi metal separation and extraction.