Effective Removal of Cesium by New Functionalized 1,3-Alternate Calixcrown Materials Immobilized on a Silica Carrier

ABSTRACT Removal of Cs isotopes, one of the heat generators present in used fuel/reprocessing waste, is one of the most challenging obstacles in the disposal of these materials. For this purpose, a new silica-calix[4]crown material, CBisC6@SiO2, has been prepared. The material was created coupling a symmetric calixcrown derivative CBisC6 into the pores and channels of the SiO2-P particles through vacuum hybridization and immobilization. SEM, 29Si solid-state CP/MAS NMR, N2 adsorption-desorption isotherms, TGA-DSC and XPS were used to characterize the structure of the final material. The adsorption of Cs and some representative metals onto CBisC6@SiO2 has been investigated in the range of 0.4 to 6.0 M HNO3. CBisC6@SiO2 showed strong adsorption ability and selectivity for Cs over all of others except for Rb in 3.0 M HNO3. The adsorption mechanism of Cs was verified using XRD and FT-IR spectra. The separation of Cs from other waste materials by CBisC6@SiO2 was performed through six adsorption-desorption cycles. The removal efficiency of Cs was 99.5%, while other fission products were weakly absorbed except for Rb with the removal efficiency of 85.3%. A nearly quantitative removal of Cs by CBisC6@SiO2 was achieved.