Adsorption of cesium and some typical coexistent elements onto a modified macroporous silica-based supramolecular recognition material

To find an effective method in separation of Cs(I), an advanced macroporous silica-based supramolecular recognition composite, (Calix[4] + MODB)/SiO2-P, was synthesized. It was done by impregnation and immobilization of 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) and methyloctyl-2-di-methy-lbutanemide (MODB) into the pores of the SiO2-P particles. MODB was used to modify Calix[4]arene-R14. The adsorption of some typical fission products such as Mo(VI), Pd(II), La(III), Y(III), Ru(III), Rh(III), Cs(I), and Zr(IV) contained in highly active liquid waste (HLW) onto (Calix[4] + MODB)/SiO2-P was investigated. It was performed by examining the effects of contact time, the concentration of HNO3 in the range of 0.3–7.0 M, and operation temperature on the adsorption of the tested metals. (Calix[4] + MODB)/SiO2-P showed strong adsorption ability and excellent selectivity for Cs(I) over all the tested metals. The separation of Cs(I) from a simulated HLW containing 5.0 mM of the tested elements was performed by (Calix[4] + MODB)/SiO2-P packed column at 298 K. Mo(VI), Pd(II), La(III), Y(III), Ru(III), Rh(III), and Zr(IV) showed no adsorption and were eluted into effluent along with 3.0 M HNO3. Cs(I) adsorbed by (Calix[4] + MODB)/SiO2-P was effectively eluted with water and then separated from the others. The results demonstrated that in 3.0 M HNO3, (Calix[4] + MODB)/SiO2-P is promising to apply in separation of Cs(I), one of the heat generators, from HLW in the SPEC (Strontium/Cesium Partitioning from HLW by Extraction Chromatography) process developed recently.