Lanthanide speciation in hydrophobic deep eutectic solvents: influence on the partition selectivity and structural properties

Non-ionic hydrophobic eutectic solvents (DES) emerged as promising substitutes for the conventional apolar phase in solvent extraction (SX) due to their enhance extractant solubility, elimination of volatile diluents, suppression of third phase formation, and incorporation of bio-compatible compound as phase formers. However, the non-ideality of the DES liquid phase makes it difficult to accurately model and predict metal partition whilst metal speciation post-SX is poorly characterized. The lack of structural characterisation hinders the wider applicability of these promising solvents and precludes their rational design for a given separation. The aim of this proposal is to get structural information on the structure of three different extracted lanthanide complexes (La, Eu, Yb) as a function of the DES nature, metal concentration and DES composition by XAS. This study will be complementary to ongoing SAXS, calorimetry, and Molecular Dynamics simulations studies.