Highly Efficient Diglycolamide-Based Task-Specific Ionic Liquids: Synthesis, Unusual Extraction Behaviour, Irradiation, and Fluorescence Studies

Two new diglycolamide-based task-specific ionic liquids (DGATSILs) were evaluated for the extraction of actinides and lanthanides from acidic feed solutions. These DGATSILs were capable of exceptionally high extraction of trivalent actinide ions, such as Am3+, and even higher extraction of the lanthanide ion, Eu3+ (about 510fold). Dilution of the DGATSILs in an ionic liquid, C4mim+NTf2, afforded reasonably high extraction ability, faster mass transfer, and more efficient stripping of the metal ion. The nature of the extracted species was studied by slope analysis, which showed that the extracted species contained one NO3 anion, along with the participation of two DGATSIL molecules. Time-resolved laser fluorescence spectroscopy (TRLFS) analysis showed a strong complexation with no inner-sphere water molecule in the EuIIIDGATSIL complexes in the presence and absence of C4mim+NTf2 as the diluent. The very high radiolytic stability of DGATSIL 6 makes it one of the most-efficient solvent systems for the extraction of actinides under acidic feed conditions.