Recent Advances in Solvent Extraction for the Efficient Recovery of Scandium: A Review

The recovery of scandium (Sc) from primary and secondary resources has gained significant attention in recent years due to its increasing demand in advanced technologies, including aerospace alloys, solid oxide fuel cells, and electronic devices. Despite its relative abundance in the Earth's crust, the dispersed nature of scandium and the lack of high-grade ores necessitate efficient separation and recovery technologies. Solvent extraction has emerged as one of the most effective methods for Sc recovery, offering advantages such as ease of process automation, scalability, and high selectivity. This review provides a comprehensive overview of research on scandium solvent extraction published since 2011, focusing on three key areas: (1) extraction using conventional extractants, highlighting challenges such as low stripping efficiency and impurity co-extraction, (2) advancements in synergic extraction systems and the design of novel extractants aimed at improving selectivity and efficiency, and (3) the application of ionic liquids (ILs) as sustainable and tunable solvents for Sc extraction. Special emphasis is placed on the role of synergic effects and the structural design of novel extractants in overcoming limitations of traditional systems. Additionally, the potential of ILs to revolutionize scandium recovery by enhancing extraction efficiency while addressing environmental concerns is discussed. This review underscores the importance of continuous innovation in extraction methodologies to meet the growing industrial demand for scandium and highlights future research directions for achieving more sustainable and efficient recovery processes.