Synthesis of bio-based solvents derived from sorbitol and stearic acid for the separation of Th, U, and REEs: a solvent extraction study

Abstract Solvent extraction is a widely used method for separating metals such as Th, U, and REEs. However, using excessive amounts of petroleum-derived solvents significantly increases the carbon footprint of the solvent extraction. In this study, bio-based solvents were synthesized in ester form using sorbitol and stearic acid. The extraction and separation performance of the synthesized bio-based solvents were evaluated for Th, U, and rare earth elements (REEs). Among the synthesized bio-based solvents, SSA2 demonstrated superior separation efficiency for Th compared to conventional extractants such as Cyanex 272 and D2EHPA. It exhibited distribution coefficient (K DTh ) and separation factor (SF Th/REE ) values of approximately 1000 and 3500, respectively.