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.