Journal Article

FZJ-2020-04089

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Does Addition of 1-Octanol as a Phase Modifier Provide Radical Scavenging Radioprotection for N,N,N’,N’-tetraoctyldiglycolamide (TODGA)?

Horne, G. P. (Corresponding author) ; Zarzana, C. A. ; Rae, C. ; Cook, A. R. ; Mezyk, S. P. ; Zalupski, P. R. ; Wilden, A.FZJ* ; Mincher, B. J.

2020
RSC Publ. Cambridge

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Please use a persistent id in citations: http://hdl.handle.net/2128/26347  doi:10.1039/D0CP04310A

Abstract: To mitigate third phase formation in next generation used nuclear fuel reprocessing technologies, the addition of 1-octanolhas been trialed. However, contradictory reports on the radiolytic effect of 1-octanol incorporation on separation liganddegradation need to be resolved. Here, 50 mM N,N,N’,N’-tetraoctyldiglycolamide (TODGA) dissolved in n-dodecane wasgamma irradiated in the presence and absence of 1-octanol (2.5-10 vol. %) and a 3.0 M HNO3 aqueous phase. RadiationinducedTODGA degradation exhibited pseudo-first-order decay kinetics as a function of absorbed gamma dose for allinvestigated solution and solvent system formulations. The addition of 1-octanol afforded diametrically different effects onthe rate of TODGA degradation depending on solvent system formulation. For organic-only irradiations, 1-octanol promotedTODGA degradation (d = 0.0057 kGy–1 for zero 1-octanol present vs. ~0.0073 kGy–1 for 7.5-10 vol. %) attributed to afavourable hydrogen atom abstraction reaction free energy (-0.31 eV) and the ability of 1-octanol to access a higher yield ofn-dodecane radical cation (RH•+) at sub-nanosecond timescales. This was rationalized by determination of the ratecoefficient (k) for the reaction of 1-octanol with RH•+, k = (1.23 ± 0.07) × 1010 M–1 s–1. In contrast, irradiation in the presenceof 1-octanol and a 3.0 M HNO3 aqueous phase afforded significant radioprotection (d = 0.0054 kGy–1 for zero 1-octanolpresent vs. ≤ 0.0044 kGy–1 for > 2.5 vol. %) that increases with 1-octanol concentration, relative to the single phase, organiconlysolutions. This effect was attributed to the extraction of sufficiently high concentrations of HNO3 and H2O into theorganic phase by TODGA and 1-octanol as adducts which interfere with the hydrogen atom abstraction process betweenthe 1-octanol radical and TODGA. Our findings suggest that the addition of 1-octanol as a phase modifier will enhance theradiation robustness of TODGA-based separation technologies under envisioned solvent system conditions in the presenceof aqueous HNO3.

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Contributing Institute(s):

1. Nukleare Entsorgung und Reaktorsicherheit (IEK-6)

Research Program(s):

1. 161 - Nuclear Waste Management (POF3-161) (POF3-161)
2. GENIORS - GEN IV Integrated Oxide fuels recycling strategies (755171) (755171)

Appears in the scientific report 2020

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Database coverage:
; ; Allianz-Lizenz / DFG ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF < 5 ; JCR ; NCBI Molecular Biology Database ; National-Konsortium ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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