Selective and irreversible adsorption mechanism of cesium on illite

• Published in: Applied geochemistry 2017-10, Vol.85, p.188-193
• Main Authors: Lee, Jeshin, Park, Sang-Min, Jeon, Eun-Ki, Baek, Kitae
• Format: Article
• Language: English
• Subjects: Cesium; Charge density; Clay minerals; FES; Hydrated-ion size; Hydration energy; Illite; Irreversible adsorption
• ISSN: 0883-2927; 1872-9134
• DOI: 10.1016/j.apgeochem.2017.05.019

Most of radioactive nuclides emitted into the air eventually fall to the ground, after then 80% of cesium fallout is fixed in soil and the other 20% is mobile as exchangeable fraction. It is most difficult to remove cesium from the soil after contamination because of the strong adsorption onto clay mineral especially illite, compared to other radionuclides and clay minerals. All the experiments were conducted using the 2:1 lattice minerals which as illite, hydrobiotite (vermiculite + biotite) and montmorillonite with 133-cesium chloride. In this study, illite had 0.25 mol/kg of frayed edge site (FES). Furthermore using the TEM-EDS confirmed selective adsorption of cesium. The selective and irreversible adsorption mechanism of cesium on illite was summarized by hydrated ion size, charge density and hydration energy. And the mechanism was proved by using barium. When cesium coexisted with barium, the adsorption efficiency to FES decreases. And when cesium adsorbed on FES was desorbed using various cations, the desorption rate was in order of ammonium > potassium > barium > calcium > magnesium, which follows the hydration energy. [Display omitted] •Adsorption of Cs was explained by hydrated ion size and charge density.•K was changed into Cs due to hydration energy.•Desorption of Cs by cations was explained by the mechanism suggested.