%0 Conference Paper
%A Sauerwein, Fynn Sören
%A Sittel, Thomas
%A Grieser, Fabian
%A Wilden, Andreas
%A Modolo, Giuseppe
%T Characterization of f-element complexes with soft-donorligands (f-Char)
%M FZJ-2023-03950
%D 2023
%X The German research project f-Char, funded by the German Federal Ministry of Education and Research (BMBF), contributes to a better understanding of the coordination chemistry of ac-tinide (An) and lanthanide (Ln) ions with ligands coordinating via soft donor atoms, e.g., N donor atoms. Since recycling of minor actinides from PUREX raffinate solution is a decisive step towards closing the nuclear fuel cycle, current research focuses on the challenging sepa-ration of Am(III) from Cm(III) and other trivalent fission lanthanides. The Americium Selective (AmSel) process[1] was designed for this task combining the water-soluble tetradentate N-do-nor ligand SO3-Ph-BTBP (tetrasodium-3,3',3'',3'''-([2,2'-bipyridine]-6,6'-diylbis(1,2,4-triazine-3,5,6-triyl))tetrabenzenesulfonate) with the well-known An(III)/Ln(III) coextracting agent TODGA (N,N,N',N'-tetra-n-octyl diglycolamide). While the separation of Am from Cm and the light Ln (La-Gd) is possible, a significant drop in distribution ratios of the heavy Ln (Tb-Lu) can be observed for ≥ 1 mol L-1 HNO3. This unusual behavior was further investigated looking at the complexation of SO3-Ph-BTBP with different Ln using different spectroscopic methods (UV/Vis, NMR). While SO3-Ph-BTBP complexation at low nitric acid concentration (10-3 mol L-1 HNO3) is observed for all lanthanides (Nd, Sm, Ho, Lu), complex formation at high nitric acid concentration (3 mol L-1 HNO3) is only observed for heavy Ln (Ho, Lu). Regardless of the nitric acid concentration, NMR spectra always show the same SO3-Ph-BTBP complex speciation with Ln. Interestingly, the complexation equilibrium for heavy Ln in 3 mol L-1 nitric acid solution is established very slowly (6 – 22 h). This effect was also confirmed by kinetic batch extraction studies and is presumably caused by the kinetically inhibited (de)complexation of the [Ln(SO3-Ph-BTBP)x] complexes. However, the mechanism is not yet understood and requires further studies.Furthermore, the two new N-donor ligands MTB (6-(6-methyl-1,2,4,5-tetrazin-3-yl)-2,2'-bipyr-idine) and PPTMP ((4-(6-(1,10-phenanthrolin-2-yl)pyridin-2-yl)-1H-1,2,3-triazol-1-yl)methyl pivalate) were tested as alternative extractants for the An(III)/Ln(III) separation. Both extract-ants were able to achieve good extraction efficiency into different diluents (tert-butylbenzene, toluene, nitrobenzene) at low nitric acid concentrations < 0.1 mol L-1 HNO3 and in presence of the lipophilic anion source 2-bromodecanoic acid.[1] C. Wagner et al., Solvent Extr. Ion Exch., 2016. 34 (2): p. 103-113, DOI: 10.1080/07366299.2015.1129192.
%B IEK-6 Institutsseminar
%C , Jülich (Germany)
M2 Jülich, Germany
%F PUB:(DE-HGF)31
%9 Talk (non-conference)
%U https://juser.fz-juelich.de/record/1017129