Separation of strontium ions from a simulated highly active liquid waste using a composite of silica-crown ether in a polymer

To partition Sr(II) from highly active liquid waste (HLW), a macroporous silica-based 4,4',(5')-di(t-butylcyclohexano)-18-crown-6 (DtBuCH18C6)-tri-n-butyl phosphate (TBP) polymeric composite, (DtBuCH18C6+TBP)/SiO2-P, was synthesized. It was done by impregnation and immobilization of DtBuCH18C6 and TBP into the pores of the SiO2-P particles, where DtBuCH18C6 was modified with TBP. The sorption of Sr(II) and some co-existent elements contained in a simulated HLW onto (DtBuCH18C6+TBP)/SiO2-P Was investigated at 323 K. It was found that in 2.0 M HNO3, Sr(II) exhibited strong sorption ability and high selectivity over all the tested metals except Ba(II). Chromatographic partitioning of Sr(II) from 2.0 M HNO3 containing 5 mM of the tested elements was performed by (DtBuCH18C6+TBP)/SiO2-P packed column. La(III), Y(III), Na(I), K(I), Cs(I), Ru(III), Mo(VI), and Pd(II) had almost no sorption and flowed into effluent along with 2.0 M HNO3. Sr(II) adsorbed strongly by (DtBuCH18C6+TBP)/SiO2-P was then eluted effectively by water, while Ba(II) flowed into effluent along with Sr(II) due to the similar chemical properties. In addition, the bleeding of total organic carbon in aqueous phase was evaluated. The results demonstrated that in 2.0 M HNO3, application of the macroporous silica-based DtBuCH18C6 polymeric composite in chromatographic partitioning of Sr(II) from the simulated HLW is feasible.