Complexation of Actinyl Ions with DHOA and TBP in an Ionic Liquid and a Molecular Solvent: How Similar or Different Are They?

Complexation thermodynamics of uranyl ions with well-known reprocessing ligands like tributyl phosphate (TBP) and dihexyl octanamide (DHOA) was studied in an ionic liquid (IL) versus a molecular solvent. Whereas 1-butyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide (Bumim·TfN) was used as an IL due to its favorable viscosity, acetonitrile was the choice of molecular solvent due to its poor coordinating nature. Optical spectroscopy studies revealed that UO ions formed species of the types ML and ML with both TBP and DHOA, in a stepwise manner.