Jump to main content
Jump to site search

Issue 43, 2020
Previous Article Next Article

Does addition of 1-octanol as a phase modifier provide radical scavenging radioprotection for N,N,N′,N′-tetraoctyldiglycolamide (TODGA)?

Author affiliations

Abstract

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

Graphical abstract: Does addition of 1-octanol as a phase modifier provide radical scavenging radioprotection for N,N,N′,N′-tetraoctyldiglycolamide (TODGA)?

Back to tab navigation

Article information


Submitted
13 Aug 2020
Accepted
16 Oct 2020
First published
19 Oct 2020

Phys. Chem. Chem. Phys., 2020,22, 24978-24985
Article type
Paper

Does addition of 1-octanol as a phase modifier provide radical scavenging radioprotection for N,N,N′,N′-tetraoctyldiglycolamide (TODGA)?

G. P. Horne, C. A. Zarzana, C. Rae, A. R. Cook, S. P. Mezyk, P. R. Zalupski, A. Wilden and B. J. Mincher, Phys. Chem. Chem. Phys., 2020, 22, 24978
DOI: 10.1039/D0CP04310A

Social activity

Search articles by author

Spotlight

Advertisements