Advancements in solvent extraction of metal ions: Mechanisms, kinetics, and efficiency with diverse extractants

This study illustrates the most recent developments and evolution of solvent extraction techniques for metal ion separation. It emphasizes the replacement of conventional extractants, such as TBP and β-diketones, with modern ones, including LIX reagents, D2EHPA, TOPO, and Cyanex reagents, as a result of enhanced design and process optimization. Recent research has demonstrated the efficacy of novel extractants in selectively targeting metal ions from complex matrices, illustrating the continuous advancements in solvent extraction techniques. In hydrometallurgy, solvent extraction is essential for the recovery, purification, and separation of both high-value and low-value metals. The review examines the history, principles, and applications of solvent extraction, with a particular emphasis on the mechanism of metal ion transfer and the characteristics of extractants such as Cyanex 272. It includes research on Mn(II) and Ni(II), as well as extractants' physicochemical properties and efficacy in selective separations. Additionally, it addresses extraction kinetics. The research also investigates surfactant properties, ligand exchange processes, and interfacial phenomena, all of which contribute to the development of environmentally benign metal extraction methods. Furthermore, it analyzes the commercial and selective separation value of extractants such as Cyanex 272, the limitations of traditional methods, the necessity for inventive alternatives, as well as historical innovations. The versatility and ongoing significance of solvent extraction in hydrometallurgical technology are underscored by mechanistic studies, which improve our comprehension of the stability constants and extraction behaviors of Mn(II) and Ni(II).