Remarkable Improvement in Am3+and Cm3+Separation Using a Cooperative Counter Selectivity Strategy by a Combination of Branched Diglycolamides and Hydrophilic Polyaza-heterocycles

Separation of Am3+and Cm3+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 Am3+and Cm3+. A separation factor (S.F.) value as high as 10 for Cm3+over Am3+was obtained in the case of TiBDGA (N,N,N′,N′-tetra-iso-butyl diglycolamide) using SO3PhBTPhen ((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 Am3+and Cm3+without involving any oxidation or reduction step. The high selectivity favoring Cm3+ion extraction in the case of this DGA derivative is also explained with the help of computational studies.