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

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)/SiO(2)-P, was synthesized by impregnating and immobilizing DtBuCH18C6 and 1-octanol into the pores of the macroporous SiO(2)-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)/SiO(2)-P were studied at 298 K. The effects of the HNO(3) concentration in a range of 0.1-5.0 M and contact time on the adsorption were investigated. (DtBuCH18C6+Oct)/SiO(2)-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 HNO(3) solution containing similar to 5.0 x 10(-3) M of the tested metals was conducted utilizing (DtBuCH18C6+Oct)/SiO(2)-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 HNO(3). Sr(II) was retained on (DtBuCH18C6+Oct)/SiO(2)-P and was eluted effectively by H(2)O, while Ba(II) showed similar elution behavior. The bleeding of total organic carbon leaked from (DtBuCH18C6+Oct)/SiO(2)-P was evaluated. It was demonstrated that the macroporous silica-based (DtBuCH18C6+Oct)/SiO(2)-P materials are promising in separation of Sr(II) from high level radioactive waste.