Direct Electrochemical Extraction of Sm from SmCl3 in a Molecular Liquid Solvent Supported By LiNO3

Abstract

Low-temperature electrochemical extraction of rare earth metals from their corresponding chlorides in ionic liquids has long been a scientific challenge. In this study, a new class of task-specific ionic liquids (ILs) containing Li elements, i.e. Li-containing solvate ionic liquids ([Li(DMI)n]3+NO3 —, 0.15 M LiNO3 dissolved in DMI (1,3-Dimethy-l-2-imidazolidinone)), is developed and used for metallic Sm electrodeposition from SmCl3. To elucidate the electrochemical deposition mechanism, the ionic component of the DMI/LiNO3 system was characterized by a range of instrumental analysis techniques (including 7Li NMR, UV-vis) and theoretical calculations. Cyclic voltammetry was used to explore the electrochemical behavior of Sm-containing species in the ionic liquid. Finally, metallic Sm was successfully obtained using constant potential deposition on high purity Al substrates which was confirmed by XPS and SEM. Li-containing solvate ILs have immense potential in green electrometallurgy because of their higher tunability and similar properties to ILs.