Evolution of activation energy for boron dissolution in the borosilicate glass during the initial leaching stage

Borosilicate glass is widely used for immobilizing high-level radioactive waste. In this study, two types of borosilicate glasses, Na-borosilicate and Zr-Na-borosilicate, were subjected to leaching within a temperature range of 50–90 °C, at 10 °C intervals. The rate of boron consumption was measured by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) and Fourier-Transform infrared spectroscopy (FTIR) techniques, and the boron activation energy was determined through the Arrhenius equation. The boron activation energies for Na-borosilicate and Zr-Na-borosilicate glasses are approximately 46 kJ/mol and 42 kJ/mol, respectively. The activation energy, which FTIR calculated, was consistent with that obtained by ICP-OES during the initial leaching time and decreased as the leaching time increased. The decrease in activation energy of boron is because the [BO₃] structure was replaced by molecular water. The FTIR method offers an alternative approach for calculating the boron activation energy and contributes to understanding the leaching mechanism in the initial leaching stage.