Static Adsorption of Cesium Ions on Kaolin/Vermiculite and Dynamic Adsorption/Desorption Using the Electrokinetic Process

The interactions between cesium Ions and two kinds of 2:1 clay minerals (kaolin and vermiculite) were investigated under batch conditions and dynamic equilibrium using the electrokinetic (EK) process. The adsorption capacities of kaolin and vermiculite were 1.2 and 18.8 mg/g, respectively, at pH 6 after 24h in the batch system. Because the basal spacing of kaolin is 0.93 nm, Cs+ ions cannot enter the interlayers. On the other hand, the basal spacing of vermiculite is 1.01 nm, and vermiculite can adsorb Cs+ ions in the interlayers. Four kinds of model soils with different ratios of vermiculite to kaolin were prepared by mixing these two types of clay minerals, and the migration behaviors of Cs+ ions in these soils on the application of the EK process were determined. The Cs+ ion migration efficiency decreased with an increase in vermiculite content. The content of vermiculite in the soil was an important factor determining the migration behavior of Cs+ ions under the dynamic equilibrium conditions produced by the EK process. The applications and limitations of the EK process for the removal of cesium from contaminated soil are discussed.