May 15 – 20, 2022
Casino Conference Centre
Europe/Prague timezone

Characterization of f-element complexes with soft-donor ligands for selective Americium separation

May 16, 2022, 6:30 PM
7m
Gallery

Gallery

Poster Separation Methods, Speciation Nuclear Fuel Cycle

Speaker

Fynn Sören Sauerwein

Description

In recent years, much effort has been invested in recycling of minor actinides from PUREX raffinate solutions. Hydrophilic N-donor ligands such as tetrasodium-3,3',3'',3'''-([2,2'-bipyridine]-6,6'-diylbis(1,2,4-triazine-3,5,6-triyl))tetrabenzenesulfonate (SO3-Ph-BTBP) are used for selective separation of Am(III) from Cm(III) and other trivalent fission lanthanides by smart combination with diglycolamide ligands as extractants such as N,N,N',N'-tetra-n-octyl diglycolamide (TODGA). In this work, the extraction behavior of SO3-Ph-BTBP in combination with TODGA and its mono- and dimethylated derivates Me-TODGA and Me2-TODGA was investigated. All systems show a high selectivity of An(III) over Ln(III), and Am(III) over Cm(III). Separation factors decrease in the order TODGA > Me-TODGA > Me2-TODGA. Moreover, a significant drop in distribution ratios of heavier lanthanides (Tb-Lu) was observed in all three extraction systems. This effect was further elucidated by speciation studies of the formed complexes with several lanthanides using UV/Vis spectroscopy. The formation of 1:2 complexes (metal-to-ligand ratio) with SO3-Ph-BTBP was confirmed for the studied lanthanides and stability constants log β of 7.7 ± 0.8 for Nd(III) at 10-3 mol L-1 HNO3 and 6.1 ± 0.4 for Ho(III) at 3 mol L-1 HNO3 were determined. No complexation was observed for Nd(III) at 3 mol L-1 HNO3. Therefore, the formation of complexes with a protonated form of SO3-Ph-BTBP seems to be possible with Ho(III), but not with Nd(III). The results of the extraction experiments and speciation studies will be presented and discussed in the poster.

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