Enhancing separation of Y(III) from Sr(II) using tributyl phosphate in a novel deep eutectic solvent media

Abstract A novel solvent extraction system was developed to separate Y 3+ from Sr 2+ , where tributyl phosphate was chosen as an extractant and an organic solvent was a hydrophobic deep eutectic solvent (DES) consisting of oleic acid (OA) and 1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl). The extraction experiment demonstrated that the extraction system using OA‐[BMIM]Cl DES as an organic solvent exhibited great advantages of fast extraction and excellent selectivity for Y 3+ (Y/Sr separation factor >500), which are hardly achieved in the extraction systems using conventional molecular solvent, for example, n ‐heptane. Density functional theory calculations also confirmed that the Y/Sr separation is more thermodynamically favorable in OA‐[BMIM]Cl DES as an organic solvent compared to n ‐heptane. An extraction process comprising two‐stage extraction, one‐stage scrubbing, and one‐stage stripping was proposed, achieving 95.06% of Y 3+ selectively separated from a simulated solution and Y purity of 98.55% in the final product.