Desorption of cesium from hydrobiotite by hydrogen peroxide with divalent cations

Abstract

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.