Effects of γ-ray irradiation on the stability and U(VI) adsorption performance of bentonite colloids

During the long-term deep geological disposal of high-level radioactive waste, buffer materials, such as bentonite, in the waste repositories are irradiated with gamma (gamma) rays, affecting their structural stability. Furthermore, bentonite colloids are formed owing to the erosion of bentonite particles by groundwater. However, the effects of prolonged irradiation on the stability of bentonite colloids and their interaction with radionuclides, which can affect the migration of the radionuclides, are yet to be elucidated. Herein, we investigated the stability of colloid prepared from irradiated bentonite with varying doses of gamma rays and conducted static adsorption batch experiments to examine their U(VI) adsorption behavior. The results showed that the stability of bentonite colloids was affected by their concentration, storage time, pH, and temperature. An investigation into their polymerization kinetics revealed that the critical coagulation concentration of bentonite colloids decreased with increasing irradiation dose, indicating that the colloids formed from unirradiated bentonite were stable. Furthermore, the U(VI) adsorption capacity of bentonite colloids decreased with increasing irradiation dose. This study provides new insights into the formation and stability of colloids of buffer materials after their irradiation and is expected to contribute significantly to the study of the migration behavior of nuclides by colloidal carriers.