Université Paris-Saclay, CEA, Service d'Etude du Comportement des Radionucléides, 91191, Gif-sur-Yvette, France.
CEA-DES-IRESNE-DTN Cadarache, F-13108, Saint-Paul-Lez-Durance, France.
Chemosphere. 2022 Feb;288(Pt 2):132582. doi: 10.1016/j.chemosphere.2021.132582. Epub 2021 Oct 20.
For understanding and predicting the Cs behavior in soils and groundwater, Cs adsorption properties of illite and vermiculite were investigated under various pH conditions and Cs concentrations. Cs adsorption and desorption experiments have been conducted with Ca-homoionic illite and Ca-vermiculite in CaCl solution with an ionic strength of 0.03 and of 0.06 mol.L respectively, by focusing on cation exchanges between Cs, proton and calcium at thermodynamic equilibrium. Ca-illite displayed more affinity for Cs than Ca-vermiculite. Cs adsorption was non-linear for both clay minerals and a multi-site exchange model approach was adopted to interpret and model adsorption isotherms. Each mineral reactivity was described by their sorption site properties expressed by their exchange capacity and ionic selectivity. High-selective and low-capacity sites were shown to control Cs uptake at concentrations below 10-10 mol.L for both Ca-illite and Ca-vermiculite. Three high-capacity sites dominated Cs adsorption at higher concentrations. Cs adsorption reversibility was demonstrated for illite at Ca concentrations ranging from 5 10 to 10 mol.L. The partial irreversibility of Cs adsorption onto vermiculite at Cs concentrations greater than 10 mol.L was related to interlayer collapse. Reversible adsorption may occur as long as the interlayer space stays open. The irreversible adsorbed fraction was quantified and taken into account in the modeling approach to calculate the selectivity coefficient of each site.
为了理解和预测 Cs 在土壤和地下水中的行为，研究了在不同 pH 值和 Cs 浓度条件下伊利石和蒙脱石的 Cs 吸附特性。在热力学平衡条件下，通过关注 Cs、质子和钙离子之间的阳离子交换，在 CaCl 溶液中用等摩尔浓度的 Ca 对同晶型伊利石和钙蒙脱石进行了 Cs 吸附和解吸实验，离子强度分别为 0.03 和 0.06 mol·L-1。与钙蒙脱石相比，钙伊利石对 Cs 具有更高的亲和力。对于两种粘土矿物，Cs 吸附都是非线性的，采用多位点交换模型方法来解释和模拟吸附等温线。通过交换容量和离子选择性来描述每个矿物的反应性，以表示其吸附位性质。在 Ca-伊利石和 Ca-蒙脱石中，高选择性和低容量的位点在浓度低于 10-10 mol·L-1 时控制 Cs 的摄取。在较高浓度下，三个高容量位点主导 Cs 的吸附。在 Ca 浓度范围为 5×10-10 至 10 mol·L-1 时，证明了伊利石的 Cs 吸附具有可逆性。在 Cs 浓度大于 10 mol·L-1 时，蒙脱石上 Cs 吸附的部分不可逆性与层间坍塌有关。只要层间空间保持开放，就可能发生可逆吸附。定量了不可逆吸附的分数，并在建模方法中考虑了每个位点的选择系数的计算。
