Self-driven electrochemical separation-recovery system for simultaneous recovery of copper, phosphate and EDTA from...

Sustainable management of electroless plating wastewater offers both environmental and economic benefits by enabling the recovery of high-value resources. In this study, we developed a self-driven electrochemical separation-recovery (SESR) system that achieves the simultaneous reclamation of copper (Cu), phosphate (P), and ethylenediaminetetraacetic acid (EDTA) from electroless copper plating wastewater, without external energy or chemical input. The system operates as a spontaneous galvanic cell, where Fe oxidation at the anode produces Fe(II), while Cu²⁺ is reduced to metallic Cu at the cathode, resulting in 93.6 % Cu recovery. The electric field generated by Fe/Cu²⁺ redox couple drives P selective migration across a monovalent anion-exchange membrane (MAEM) into anodic chamber, where it reacts with Fe²⁺ to form vivianite (Fe₃(PO₄)₂·8H₂O) crystals, achieving a P recovery efficiency of 78.6 %. In contrast, multivalent free EDTA ligands and Cu-EDTA complexes are effectively retained, with > 89.2 % rejection of total EDTA (T-EDTA). The separation process is governed by charge-selective transport behavior, particularly under mildly acidic condition (pH 4.0-6.0). Key operational parameters, including membrane types, initial solution pH, and cathode materials, were systematically investigated. The SESR system demonstrated stable performance in treating real wastewater, successfully recovering high-purity (> 95.0 %) metallic Cu and well-defined vivianite crystals. Overall, this study establishes a robust, self-sustained electrochemical platform for integrated, selective, and sustainable separation and reclamation of multi-resources from complex industrial wastewater.