Wang Jinsheng, Cai Weihai, Zuo Rui, Du Can
College of Water Sciences, Beijing Normal University, Beijing 100875, China.
Engineering Research Center of Groundwater Pollution Control and Remediation, Ministry of Education, Beijing 100875, China.
Int J Environ Res Public Health. 2022 Aug 12;19(16):9970. doi: 10.3390/ijerph19169970.
Colloids have a significant influence on the migration of nuclides in claystone, which is an important geological barrier. The sorption of strontium on claystone in the presence of FeOOH colloids was investigated in samples from the Suhongtu site, a candidate high-level radioactive waste disposal site in China. The effects of colloid amount, solid content, and pH were investigated by batch tests, and the sorption reaction mechanism was analyzed by kinetic modeling and microscopic characterization techniques. The results indicate that the sorption of Sr by claystone increased with the solids content, and the claystone had a stronger Sr sorption capacity under alkaline conditions. The Sr sorption kinetics were best described by the pseudo-first-order and pseudo-second-order models, which revealed that the progress is affected by physical diffusion and chemical sorption. Furthermore, the microscopic characterization results demonstrate that cation exchange reactions and surface complex reactions are the main sorption mechanisms for Sr sorption on claystone. Ca and Mg plasmas in claystone minerals can have cation replacement reactions with Sr, and functional groups such as -OH and [CO] can have complexation reactions with Sr to adsorb Sr on the surface of the claystone. Additionally, the presence of the FeOOH colloid inhibited the sorption effect of claystone slightly. The FeOOH colloid could occupy sorption sites on the claystone surface, which reduces the activity of the functional groups and inhibits the sorption of Sr on claystone.
胶体对核素在作为重要地质屏障的泥岩中的迁移有显著影响。在中国一个候选的高放废物处置场苏红图场址的样品中，研究了在FeOOH胶体存在下锶在泥岩上的吸附情况。通过批量试验研究了胶体含量、固体含量和pH值的影响，并通过动力学建模和微观表征技术分析了吸附反应机理。结果表明，泥岩对Sr的吸附量随固体含量的增加而增加，且泥岩在碱性条件下具有更强的Sr吸附能力。Sr吸附动力学用准一级和准二级模型描述最佳，这表明其过程受物理扩散和化学吸附影响。此外，微观表征结果表明阳离子交换反应和表面络合反应是Sr在泥岩上吸附的主要机制。泥岩矿物中的Ca和Mg等离子体可与Sr发生阳离子置换反应，-OH和[CO]等官能团可与Sr发生络合反应，从而将Sr吸附在泥岩表面。此外，FeOOH胶体的存在略微抑制了泥岩的吸附效果。FeOOH胶体可占据泥岩表面的吸附位点，这降低了官能团的活性并抑制了Sr在泥岩上的吸附。
