Desorption of cesium from hydrobiotite by hydrogen peroxide with divalent cations

In this study, hydrogen peroxide (H₂O₂) was used to enhance the cation-exchange treatment for Cs⁺ desorption from clay minerals. Among various investigated clay minerals, hydrobiotite (HBT), which has interstratified layers of vermiculite and biotite, exhibited the highest Cs⁺ sorption capacity and the most favorable H₂O₂ activation because of its high Fe content. In X-ray diffraction analysis, HBT treated with H₂O₂ and 0.1 M Mg²⁺ showed substantial changes in its basal spacing, indicating expansion of the interlayer region induced by treatment of H₂O₂ and strongly hydrated divalent cations. In addition, more than 80% of the Cs⁺ was readily desorbed from HBT with 35% H₂O₂ solution and 0.1 M Mg²⁺ at room temperature. After three cycles under the same treatment conditions (35% H₂O₂ solution and 0.1 M Mg²⁺), approximately 99% removal of radioactive Cs⁺ was achieved. These results suggested that H₂O₂ treatment with solvated Mg²⁺ enhanced Cs⁺ desorption from HBT by altering the interlayer region through intercalation of hydrated divalent cations in conjunction with the H₂O₂ decomposition reaction.