The effect of aliphatic alcohol additives on the radiolytic degradation of TODGA in Isopar-M
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The effect of aliphatic alcohol additives on the radiolytic degradation of TODGA in Isopar‑M Yulia V. Nikitina1 · Nikolay V. Yudin2 · Elena V. Belova1 · Alexander V. Ponomarev1 Received: 8 June 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The radiolysis of solutions of TODGA (N,N,N′,N′-tetra-n-octylamide of diglycolic acid) in mixtures of Isopar-M (isoparaffins C13–C14) with n-nonanol or n-decanol at 500 kGy leads to predominant decomposition of TODGA. The radiationchemical yield of this process is 0.4–0.5 μmol J−1. The main products of the direct effect of ionizing radiation on TODGA are N,N-dioctylacetamide and 2-hydroxy-N,N-dioctylacetamide. The indirect effect of ionizing radiation is mainly due to reactions with alkoxy radicals and leads to the breaking of the C–N and C–C bonds in the α-position relative to the carbonyl group. An increase in the alcohol content in the solution results in the increase of the variety of radiolytic products, in the enhancement of gas evolution, and in the increase in the yield of TODGA decomposition. The replacement of n-decanol with n-nonanol does not significantly affect the radiolytic stability of the solutions. Keywords TODGA extractant · n-alcohols · Radiolysis products · Radiation-chemical yield
Introduction One of the critical characteristics of systems used to extract radionuclides from spent nuclear fuel is the radiolytic stability of the extractant and the whole system. Among the various extractants, diglycolamides [1–4], primarily TODGA—N,N,N′,N′-tetra-n-octylamide of diglycolic acid, are of the most significant practical interest considering high extraction ability and ease of utilization. TODGA solutions in mixtures of heavy paraffins with aliphatic alcohols, in particular in the mixture of iso-paraffins C13–C14 (Isopar-M) with n-nonanol or n-decanol, are promising for practical use not only due to extraction efficiency and the possibility to regenerate the organic solutions but also due to their fire and explosion safety [5]. These mixtures are also promising for the extraction of An(III) and Ln(III) from solutions with a high concentration of nitric acid [6–8]. However, the optimal composition of the extraction systems must be determined * Elena V. Belova bl174@bk.ru 1
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, 31/4 Leninsky prospect, Moscow, Russia 119071
D. Mendeleev University of Chemical Technology of Russia, 20/1 Geroyev Panfilovtsev str., Moscow, Russia 125480
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based on the information, including their radiolytic stability. The radiolytic transformations of TODGA in hydrocarbonalcohol solutions have not been previously experimentally studied. However, TODGA molecules’ ability to serve as effective acceptors of excessive energy and charge in mixtures with dodecane was shown using pulsed radiolysis and stationary γ-radiolysis [9, 10]. The aim of this work is the analysis of key transformations and products of the radiolysis of TODGA solutions in a mixture of Isopar-M with n-decano
