13-18 May 2018
Casino Conference Centre
Europe/Prague timezone

Partitioning of minor An(III) and Ln(III) by the 1,2,4-triazine extracting compounds

15 May 2018, 14:15
15m
Marble Hall (Casino Conference Centre)

Marble Hall

Casino Conference Centre

Reitenbergerova 4/95, Mariánské Lázně, Czech Republic
Verbal Chemistry of Nuclear Fuel Cycle, Radiochemical Problems in Nuclear Waste Management NFC 3

Speaker

Jan John (CTU in Prague)

Description

Partitioning of trivalent minor actinoids from lanthanoids and mutual separation of minor actinoids is a current issue studied within reprocessing of irradiated nuclear fuel and nuclear reactors of the IV$^{th}$ generation, i.e. closing of a nuclear power cycle. The objective of this contribution is to summarize results obtained for various liquid-liquid or solid-liquid extraction systems, and/or hydrophilic masking agents based on 1,2,4-triazine extracting compounds (BTP, BTBP, BTPhen) proposed for separation of the above mentioned groups of elements. Properties of new monohalogenated CyMe$_{4}$-BTBP were compared with the reference molecule of r-SANEX, CyMe$_{4}$-BTBP. The monohalogenated BTBP were much better soluble in octan-1-ol and cyclohexanone. Obtained values of Am/Eu separation factor (SF$_{Am/Eu}$ > 110) were similar to the reference molecule but without the need to use a phase transfer agent. The best results for mutual separation of minor actinoids were obtained in extraction system with CyMe$_{4}$-BTPhen where a kinetic separation effect SF$_{Am/Eu}$ = 7.9 was observed in the mixture of octan-1-ol with toluene, while in cyclohexanone SF$_{Am/Eu}$ was equal to 5.5–6.7. This effect was explained by computational modelling. Hydrophilic sulfonated ligands were tested for their ability to complex Am(III) and prevent its extraction by TODGA within the i-SANEX process. Four various tetrasulfonated BTBP or BTPhen ligands were able to selectively complex Am(III) in 0.28–0.77 mol/L HNO$_{3}$; SF$_{Am/Eu}$ = 138–934 was achieved by extraction to TODGA. The described system provides a possible alternative to the American TALSPEAK process as it works at higher HNO$_{3}$ concentrations and without the use of any buffer. The highest value of SF$_{Cm/Am}$ = 4.6 for mutual minor actinoids separation was obtained with tetrasulfonated BTPhen in aqueous phase. TODGA-PAN composite sorbent performed well for chromatographic Cm(III) and Am(III) partitioning with SF$_{Cm/Am}$ = 4 when tetrasulfonated BTPhen was used as an eluting agent. The best system for solid-liquid extraction was the BTPhen–SiO$_{2}$–Fe$_{2}$O$_{3}$ MNP. It can be used for selective separation of Am(III) at higher acidities with values of SF$_{Am/Eu}$ ≈ 1670, and as a non selective extraction system for Am(III), Eu(III), and Cm(III) at lower acidities with values of mass distribution coefficient D$_{w}$ > 700.

Primary authors

Petr Distler (CTU in Prague) Ashfaq Afsar (University of Reading) Kamila Šťastná (CTU in Prague) James Westwood (University of Reading) Frank W. Lewis (Northcumbria University) Karel Štamberg (CTU FNSPE, katedra jaderné chemie) Prof. Laurence Harwood (University of Reading) Jan John (CTU in Prague)

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