Extraction of trivalent americium and europium with TODGA homologs from HNO3 solution

Two diglycolamide homologs, N,N,N',N'-tetraoctyl-3,6-dioxaoctane diamide (DOODA) and N,N,N',N'-tetraoctyl-3,6,9-trioxaundecane diamide (TOUDA), were synthesized. Their extraction behaviors of Am3+ and Eu3+ were investigated and compared with those of N,N,N',N'-tetraoctyl-3-oxapentane diamide (TODGA). The extraction ability toward Am3+ and Eu3+ decreased with increasing etheric oxygen number in the extractant structure. In contrast to TODGA, an very interesting inversion on the selectivity occurred for DOODA and TOUDA, which were more favor of extracting Am3+ than Eu3+. The maximum SFAm/Eu of 3.5 for DOODA can be achieved at 3.0 mol/L HNO3. The stoichiometries of extracted species and extraction thermodynamic parameters were also presented.