Sustainable Metal Mixture Separation From E-Waste Leaching: Flow-Based System Approach With Closed-Loop Reutilization of Organic Ligands

Journal article, 2026

As the amount of electronic waste (e-waste) continues to grow at an unprecedented rate, the development of efficient and sustainable metal-recycling methods has become an urgent priority for achieving a greener world. This study reports a flow-based liquid–liquid extraction system for the selective separation of copper from copper–silver leachates obtained from e-waste provided using batch leaching with methanesulfonic acid (MSA), a biodegradable and nonoxidizing acid. The selective extraction of copper was achieved using a phenolic oxime, owing to its high affinity for Cu(II) ions. To adjust the optimal conditions, we have screened the effects of different flow rates and residence times on extraction efficiency and also the different metal-to-ligand ratios. Optimal conditions were obtained using a metal-to-ligand ratio of 1:3 and a flow rate of 0.4 ml⁻¹, resulting in a maximum extraction efficiency of 97%. To enhance process sustainability and reduce solvent consumption, a ligand/solvent regeneration step was integrated, enabling copper back-extraction, recycling of the organic extractant, and implementation of a closed-loop process. Accordingly, this work presents an approach designed to improve the sustainability of e-waste recycling through selective metal recovery and closed-loop reutilization of the ion-selective ligand.