Abstract Bentonite colloids are readily generated by eroding the compacted bentonite blocks with flowing groundwater and facilitate the transport of radionuclides due to their high mobility. The geological fate of colloids is highly relevant to the aggregation and sedimentation of colloids in porous media. In the present work, the week-scale stability of bentonite colloids concerning sedimentation was determined by photon correlation spectroscopy (PCS) as a function of pH, temperature, and electrolyte concentration. The related mechanisms governing colloidal stability were elucidated by employing the DLVO model. The results showed that the alkaline condition was favorable for bentonite colloidal stability, while high temperature and high salinity destabilized colloids due to the decrease in repulsive potential energy. Ca2+ contributed more significantly to colloid sedimentation than Na+ because of the favorable replacement in the Stern layer. The critical coagulation concentration (CCC) values calculated theoretically from DLVO theory were applicable to predict the stability of bentonite colloids. Knowledge from the present work provides deep insight into the stability of bentonite colloids and has potential implication for understanding the detailed physico-chemical processes governing colloid migration under various subsurface environments.

中文翻译：

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GMZ 膨润土胶体在水溶液中沉降的动力学测定：pH、温度和电解质浓度的影响

摘要 膨润土胶体很容易通过流动的地下水侵蚀压实的膨润土块而产生，并且由于其高流动性而有利于放射性核素的传输。胶体的地质归宿与胶体在多孔介质中的聚集和沉降高度相关。在目前的工作中，膨润土胶体在沉降方面的周尺度稳定性是通过光子相关光谱 (PCS) 作为 pH、温度和电解质浓度的函数来确定的。采用DLVO模型阐明了控制胶体稳定性的相关机制。结果表明，碱性条件有利于膨润土胶体的稳定性，而高温和高盐度由于排斥势能的降低而使胶体不稳定。由于 Stern 层中的有利置换，Ca2+ 对胶体沉降的贡献比 Na+ 更显着。根据DLVO理论理论计算的临界混凝浓度（CCC）值适用于预测膨润土胶体的稳定性。从目前的工作中获得的知识为深入了解膨润土胶体的稳定性提供了潜在的意义，对于理解在各种地下环境下控制胶体迁移的详细物理化学过程具有潜在意义。