Radiolytic and hydrolytic degradation of the hydrophilic diglycolamides

ABSTRACT

The stability of different hydrophilic diglycolamides against acid degradation and radiolysis was studied. Tetraethyldiglycolamide (TEDGA) was found to undergo degradation in nitric acid at high reaction rates at elevated temperatures with a maximum of a ~8% decrease per hour at 65°C in 4 mol L^–1 HNO₃. The radiolysis was studied for tetramethyldiglycolamide (TMDGA), TEDGA, methyl-tetraethyldiglycolamide (Me-TEDGA), and dimethyl-tetraethyldiglycolamide (Me₂-TEDGA). The degradation rates decreased with increasing molecular weight, following the trend TMDGA > TEDGA > Me-TEDGA ≥ Me₂-TEDGA. Degradation products were identified by mass spectrometric techniques and were found to be comparable to those previously reported for the radiolysis of lipophilic diglycolamides in dodecane. Significant insight into the degradation mechanism in water was gained using pulse radiolysis experiments. The ^•OH radical was identified as the most important reactive species and predominant mechanism of radical reaction is one of electron transfer rather than H-atom abstraction.

KEYWORDS:

• Hydrolysis
• radiolysis
• pulse radiolysis
• diglycolamides
• TEDGA
• radical reaction

Additional information

Funding

Work at INL was funded by the United States Department of Energy (US DOE) Assistant Secretary for Nuclear Energy, Fuel Cycle Research and Development Radiation Chemistry Program, DOE-Idaho Operations Office Contract DE-AC07-05ID14517. Work at CSULB was conducted under US DOE Nuclear Energy Universities program DE-NE-0008406. Financial support for this research was provided by the European Commission from the H2020 Euratom Research and Innovation Programme (Grant number 755171; project GENIORS). We want to thank Beatrix Santiago-Schübel for support with the HRMS measurements.