Wanner H, Albinsson Y, Wieland E
MBT Umwelttechnik AG, Vulkanstrasse 110, CH-8048, Zürich, Switzerland.
Anal Bioanal Chem. 1996 Mar;354(5-6):763-9. doi: 10.1007/s0021663540763.
Caesium sorption on Wyoming bentonite MX-80 has been studied in solutions of NaCl, KCl, MgCl(2), CaCl(2), NaNO(3) and Ca (NO(3))(2) of concentrations varying between 0.025 and 1 mol/L, as well as in a weakly saline (I=0.004 ml/L) and a strongly saline (I=0.46 mol/L) natural groundwater. These experiments have been used to derive a thermodynamic model for the interaction of caesium with the bentonite surface in accordance with a surface chemical model, including acid/base reactions developed recently for montmorillonite. The sorption behaviour of caesium on bentonite can be described, within the experimental and model uncertainties, in terms of a one-site ion exchange model. The ion exchange constant obtained for the reaction NaX+Cs(+) left arrow over right arrow CsX+Na(+) (where X represents the ion exchange sites on montmorillonite) is log(10) K(0)(ex)=1.6. Impurities in the bentonite, influencing the concentrations of competing cations, such as Na(+), K(+), Mg(2+) and Ca(2+), have a crucial impact on the sorption of caesium. This impact can be adequately quantified with the present model. The model predictions compare well with sorption data published in the open literature on both Wyoming bentonite MX-80 and other types of bentonite. Distribution coefficients from the literature obtained from both batch and diffusion experiments and varying over four orders of magnitude are reproduced and explained successfully by the model.
已在浓度介于0.025至1 mol/L之间的NaCl、KCl、MgCl₂、CaCl₂、NaNO₃和Ca(NO₃)₂溶液中，以及在弱盐水（I = 0.004 mol/L）和强盐水（I = 0.46 mol/L）天然地下水中，研究了铯在怀俄明膨润土MX - 80上的吸附情况。这些实验已用于根据表面化学模型推导铯与膨润土表面相互作用的热力学模型，该模型包括最近为蒙脱石开发的酸碱反应。在实验和模型不确定性范围内，铯在膨润土上的吸附行为可用单点位离子交换模型来描述。反应NaX + Cs⁺⇌CsX + Na⁺（其中X代表蒙脱石上的离子交换位点）得到的离子交换常数为log₁₀K₀(ex)=1.6。膨润土中的杂质会影响竞争阳离子（如Na⁺、K⁺、Mg²⁺和Ca²⁺）的浓度，对铯的吸附有至关重要的影响。这种影响可用当前模型进行充分量化。该模型预测结果与公开文献中发表的关于怀俄明膨润土MX - 80和其他类型膨润土的吸附数据比较吻合。该模型成功再现并解释了文献中通过批量实验和扩散实验获得的、范围跨越四个数量级的分配系数。
