Solvent extraction of Eu, Th, U and Am by N,N′-dimethyl-N,N′-dihexyl-3-thiopentanediamide and thenoyltrifluoroacetone

The diamide, N,N'-dimethyl-N,N'-dihexyl-3-thiopentanediamide (DMDHTPDA) was synthesized and tested for extraction of Eu(III), Am(III), Am(III), Th(IV) and U(VI). DMDHTPDA shows a very weak complexation with these metal ions, which can be attributed to the soft base nature of the sulfur atom. None of the cations were extracted into the organic phase when DMDHTPDA alone was present. Synergistic extraction was measured for DMDHTPDA plus thenoyltrifluoroacetone. From the extraction dependencies on pH and extractant concentration, formation of mixed TTA + DMDHTPDA complexes were indicated. Except for the Th(IV) system, the separation and synergistic factors were smaller for the ?TA + DMDHTPDA extractant than for the system of TTA + DMDHOPDA (the oxo ether analog of DMDHTPDA).