Preparation of macroporous silica-based crown ether materials for strontium separation

Abstract

To develop a separation process of Sr(II), a macroporous silica-based 4,4′,(5′)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) polymeric material, (DtBuCH18C6+Oct)/SiO2-P, was synthesized by impregnating and immobilizing DtBuCH18C6 and 1-octanol into the pores of the macroporous SiO2-P particles support. DtBuCH18C6 was modified with 1-octanol through hydrogen bonding. The adsorption of simulant elements of some typical fission products Ru(III), Pd(II), Ba(II), Mo(VI), La(III), Y(III), Sr(II), Cs(I) and those of non-fission products Na(I) and K(I) onto (DtBuCH18C6+Oct)/SiO2-P were studied at 298 K. The effects of the HNO3 concentration in a range of 0.1–5.0 M and contact time on the adsorption were investigated. (DtBuCH18C6+Oct)/SiO2-P showed excellent adsorption ability and high selectivity for Sr(II) over all of the tested metals except Ba(II). Partitioning of Sr(II) from a 2.0 M HNO3 solution containing ~5.0 × 10−3 M of the tested metals was conducted utilizing (DtBuCH18C6+Oct)/SiO2-P packed column. Pd(II), Mo(VI), Y(III), La(III), Ru(III), K(I), Cs(I), and Na(I) showed no adsorption and flowed into effluent along with 2.0 M HNO3. Sr(II) was retained on (DtBuCH18C6+Oct)/SiO2-P and was eluted effectively by H2O, while Ba(II) showed similar elution behavior. The bleeding of total organic carbon leaked from (DtBuCH18C6+Oct)/SiO2-P was evaluated. It was demonstrated that the macroporous silica-based (DtBuCH18C6+Oct)/SiO2-P materials are promising in separation of Sr(II) from high level radioactive waste.