Remarkable Improvement in Am and Cm Separation Using a Cooperative Counter Selectivity Strategy by a Combination of Branched Diglycolamides and Hydrophilic Polyaza-heterocycles.

Separation of Am and Cm is one of the most challenging problems in the back-end of the nuclear fuel cycle. In the present work, we exploited the cooperative effect of the opposite selectivity of hydrophobic branched DGA derivatives and hydrophobic N-donor heterocyclic ligands taken in two different phases to achieve improved separation behavior. A systematic study was performed using a series of DGA derivatives to understand the effect and the position of branching in the alkyl chains on the separation behavior of Am and Cm. A separation factor (S.F.) value as high as 10 for Cm over Am was obtained in the case of TiBDGA (','-tetra--butyl diglycolamide) using SOPhBTPhen ((phenanthroline-2,9-diyl)-1,2,4-triazine-5,5,6,6-tetrayltetrabenzenesulfonic acid) as the aqueous complexant, which is the highest reported value so far for the ligand-based separation of Am and Cm without involving any oxidation or reduction step. The high selectivity favoring Cm ion extraction in the case of this DGA derivative is also explained with the help of computational studies.