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| Home > Publications database > Bistriazolyl-phenanthroline ligand for sustainable Am(III) separation from simulated spent nuclear fuel solutions |
| Master Thesis | FZJ-2026-03338 |
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2026
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Please use a persistent id in citations: doi:10.34734/FZJ-2026-03338
Abstract: Following the recovery of U and Pu from used nuclear fuel, Am becomes the primary contributorto the long-term radiotoxicity and heat load of the remaining high level waste.The AmSel (Americium Selective) process has been developed for the selective strippingof Am from PUREX (Plutonium Uranium Reduction Extraction) raffinate. It is basedon the combined use of two ligands with opposite selectivity and solubility, which workin a push-pull system, allowing a satisfactory separation of Am from Cm and all the lanthanides(Ln). Ethoxyethanol-bis-triazolyl-phenanthroline (EBTzPhen) was investigatedas an alternative made only by C, H, O and N to the reference sulphonated hydrophilicligand. A CHON-compliant molecule can be incinerated without the formation of secondarysolid waste, improving the sustainability of the process. The aim of the study wasto assess the extraction performance of the EBTzPhen and its selectivity towards Am,in presence of Cm and all the Ln. The behaviour of the system was investigated withbatch experiments as a function of different parameters, relevant for the process: initialligand and nitric acid concentration, temperature and mixing time. Distribution ratiosand separation factors were evaluated for all the ions by gamma and alpha spectrometryand ICP-MS measurements. To better understand the complexation mechanism, a UVVISmetal titration was carried out with Eu nitrate. Heavy Ln were extracted almostcompletely into the organic phase, while light Ln tended to remain in the aqueous phase,with La being the most retained. Am separation was obtained with 0.1 M ligand and0.3 M nitric acid concentrations: Cm and La were extracted in the organic phase, whileAm was retained in the aqueous phase, yielding separation factors around 2-2.5 for bothCm/Am and La/Am, ensuring no co-extraction. The molecule exhibited fast kinetics,but the system proved to be affected by temperature. Finally, complexation appearedto be affected both by protonation and by the molecule’s structure itself. The resultsobtained in this work demonstrate the potential of EBTzPhen as a promising CHONcompliantalternative for the AmSel process and provide critical insights to further refinethe molecular design.
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