Effect of Europium Complexation on N,N,N ,N -Tetraoctyldiglycolamide Degradation Against Gamma Radiation

Abstract

Diglycolamide extractants (DGAs) are playing an important role for many of aqueous separation processes under development for the advanced nuclear fuel cycle. This family of ligands exhibits excellent extracting and resistant properties, with TODGA (N,N,N′,N′-tetraoctyldiglycolamide) being a particularly successful extractant studied intensively in recent decades. Nowadays, the main issues for TODGA-based solvents are related to the understanding and simulation of the radiolytic degradation under realistic conditions, which is limiting aspect for the development of an advanced aqueous nuclear separation process. In that sense, in this work, TODGA ligand stability, solvent composition and performance were evaluated considering the effect of metal complexation under gamma radiation. For that, the irradiation of a TODGA solvent in the presence of Eu metal was carried out, varying the ligand/metal ratio. The goal was to not only study TODGA degradation using HPLC–MS technique but also to identify and quantify its degradation compound under these experimental conditions. The results revealed a protection of TODGA molecules due to metal ion complexation, with no observed changes in the degradation pathway, as confirmed by the quantification of formed degradation compounds.