Sequential recovery of lead and zinc from wastewater coupled with chlor-alkali electrolysis in a membrane reactor

The treatment of heavy metal-contaminated wastewater remains a critical challenge due to the coexistence of multiple metal ions and the lack of efficient recovery strategies. Herein, we report an H-type electrochemical membrane reactor that enables the sequential recovery of Pb 2+ and Zn 2+ from multicomponent wastewater while simultaneously driving chlor-alkali electrolysis. The system operates in a two-electrode configuration with a polysulfone-ZrO 2 composite membrane, which prevents cross-contamination between the compartments and stabilizes the local pH environment. In a solution containing 0.01 M Pb 2+ and 0.01 M Zn 2+ , Pb 2+ is preferentially reduced and deposited as fluffy lead with 99.3% recovery efficiency after 10 h of galvanostatic electrolysis at 10 mA cm −2 . When most of Pb 2+ is depleted, the hydrogen evolution reaction becomes dominant, raising the pH and inducing the precipitation of Zn 2+ as Zn(OH) 2 with 99.8% recovery efficiency, which is subsequently converted to ZnO. The membrane improves Pb 2+ /Zn 2+ recovery efficiencies and reduces energy consumption compared with the membrane-free system. The anode produces Cl 2 with Faradaic efficiency >95%, and the cathode generates H 2 (with Faradaic efficiency: from 1.6% at 1 h to 99.2% at 10 h) and NaOH. This integrated strategy offers a sustainable pathway for the stepwise recovery of metal resources from complex wastewater while co-generating valuable chemicals.