The effect of radiolysis and thermally stimulated acid hydrolysis on tributyl phosphate and its solutions in ISOPAR-M

Abstract

The radiolytic and post-radiation thermochemical (at 90–170 °C) transformations of tri-n-butyl phosphate (TBP) and its 30% solution into Isopar-M during pre-radiation and post-radiation acidification with nitric acid have been investigated. The assortment of nitrogen-containing products of TBP oxidation during gamma radiolysis, electron beam radiolysis, and thermally stimulated acid hydrolysis is similar. Specific products of radiolysis are TBP dimer and alkyl adducts of dibutyl phosphate, and specific products of thermolysis are ethylbenzene and xylenes. It was shown that, in contrast to 100% TBP, where radiolysis and hydrolysis have approximately the same additive effect on the degradation of TBP, hydrolysis in a 30% solution leads to the degradation of nitrogen-containing radiolysis products and additional formation of dibutyl phosphate and monobutyl phosphate. Temperatures above 110 °C during post-radiation thermolysis intensify the formation of highly volatile compounds from radiolysis products (up to 17 wt% at 170 °C), which increases the fire and explosion hazard of using extraction mixtures.