SELECTIVE SEPARATION OF COPPER AND ZINC IONS FROM INDUSTRIAL EFFLUENTS USING ORGANIC COMPLEXING AGENTS: MECHANISMS AND PROCESS DESIGN

Abstract

Industrial effluents often contain elevated concentrations of heavy-metal ions, including copper (Cu²⁺) and zinc (Zn²⁺). The selective removal and recovery of these ions are critically important from both environmental and resource-recovery perspectives. This article reviews current knowledge of organic complexing agents (chelators, extractants) applied to the selective separation of copper and zinc ions from industrial wastewater streams and secondary process liquors, analyzes underlying mechanisms (complexation, solvent extraction, ion exchange, selective stripping), and discusses process design considerations and challenges. Particular attention is given to factors influencing selectivity between Cu(II) and Zn(II), including ligand structure, aqueous phase chemistry (pH, chloride, sulfate, competing ions), organic-phase modifiers, phase ratio, stripping strategy, and regeneration. Case studies of solvent extraction systems (e.g., 1,1′-didecyl-2,2′-bibenzimidazole, bifunctional extractants such as Kelex 100) are analysed, and prospects for integration into industrial wastewater treatment and metal recovery schemes are considered.