Selective Removal and Recovery of Cu ²⁺ From Complex Water via Asymmetric Electrochemical Separation System

ABSTRACT Industrial wastewater pollution and resource shortage are major issues affecting environmental sustainability today. Copper, a critical metal, is also a prevalent heavy metal contaminant in aquatic environment. Selective extraction/recovery of low‐concentration Cu ²⁺ from wastewater remains a hurdle. Herein, we develop an asymmetric electrochemical separation system to selectively capture Cu ²⁺ from complicated water with the composite of covalent organic frameworks (COFs) and hollow mesoporous carbon spheres (HMCS) serving as cathode. By taking advantage of their synergistic effects, the HMCS@COF with suitable component proportion enables good electrical conductivity, fast ion movement, and full exposure of Cu ²⁺ capture sites, achieving 97% Cu ²⁺ removal and a Cu ²⁺ /Na ⁺ selectivity of 10.54 at 1.2 V in 20 mg L ⁻¹ Cu ²⁺ and 100 mg L ⁻¹ Na ⁺ with additional involvement of minor electrodeposition route. Even in mixed solutions containing various metal ions (Na ⁺ , K ⁺ , Ca ²⁺ , Mg ²⁺ , Zn ²⁺ , Ni ²⁺ , Fe ³⁺ ), it maintains high removal efficiency and selectivity for Cu ²⁺ . Moreover, satisfactory regenerability and stability are displayed over continuous operational cycles. The remarkable preferential removal of Cu ²⁺ is also demonstrated by theoretical calculations. This work provides a new route for the selective removal of Cu ²⁺ and offers the potential for copper recovery from wastewater containing multiple metals.