Electrochemical depopulation of waste printed circuit boards (WPCBs) with simultaneous recovery of tin

Abstract Waste printed circuit boards (WPCBs) represent a highly complex waste stream. Copper and insulating layers are integrated into a dense composite material that is populated with a diversity of electronic components (ECs) mounted with tin-based solder. This results in a high material variety, which poses a major challenge for recycling. In this study, we demonstrated an electrochemically stimulated depopulation method to reduce this complexity by liberating the ECs from the board for separate, more efficient downstream recycling, while simultaneously recovering metallic tin. In particular, one-step electrochemical dissolution of solder and deposition of pure tin was achieved in a methanesulfonic-based electrolyte. To demonstrate the feasibility, the WPCBs were placed in an anode basket consisting of a metallic net, a polyethylene anode bag, and graphite conducting flakes. The resulting process exhibits a low energy consumption of 140 to 340 kWh/t(Sn) at a cathodic current efficiency of over 92%, while achieving depopulation efficiencies up to 90% (constant current) and 87.5% (constant anodic potential), respectively.