Batch and Continuous Flow Method of Separation and Recovery of Co(II) and Ni(II) Using an Analog of Glycine-Betaine Based Ionic Liquid

This study presents an innovative approach for the selective extraction of Co(II) and its separation from Ni(II) using ethyl ester glycine-betaine derivatives, specifically tri(n-pentyl)[2-ethoxy-2-oxoethyl]ammonium dicyanamide, as extractants in combi-nation with continuous-mode liquid–liquid contact. Semi-pilot-scale implementation requires non-equilibrium conditions, characterized by short contact times between ef-fluent and extractant phases. To address this, we propose dissolving analog of gly-cine-betaine ionic liquid (AGB-IL) in low-viscosity MIBK solvents to enhance mass transfer while reducing dependence on fossil-based solvents. Liquid–liquid extraction and continuous-flow stripping experiments were designed based on prior batch results and conducted in a saline environment, employing a chaotropic electrolyte for extrac-tion and a kosmotropic electrolyte for stripping. Both open and closed systems were tested to compare extractive performance with batch conditions and with scenarios representative of industrial operations. Results indicate that continuous-flow systems achieve performance comparable to batch systems in terms of extraction efficiency, Co/Ni separation coefficients, and recyclability. These findings provide proof of con-cept for the development of semi-pilot and pilot-scale processes for efficient cobalt re-covery.