摘要
In this study, the stability of MX-80 bentonite colloids and the sorption behavior of cesium were investigated under chemically controlled conditions relevant to radioactive waste repository environments. Colloid stability was evaluated using particle size distribution, zeta potential, and visual aggregation behavior under deionized water (DIW), synthetic groundwater (GW), and NaCl electrolyte solutions with different ionic strengths. Stable colloidal suspensions were observed under low ionic strength conditions, whereas rapid aggregation and settling occurred under saline conditions. Zeta potential measurements indicated strong electrostatic stabilization in DIW but near-neutral surface charge conditions in GW. Sorption experiments showed rapid Cs association with bentonite colloids under DIW conditions, while sorption behavior was significantly reduced in GW due to high ionic strength effects. Isotherm results showed approximately linear sorption behavior within the investigated dilute concentration range. The results demonstrate that bentonite colloid stability and radionuclide association behavior are strongly dependent on groundwater chemistry and ionic strength. From a safety assessment perspective, the findings suggest that colloid-related radionuclide behavior should be evaluated under chemically dependent conditions, particularly in low ionic strength environments favorable for colloid persistence.