SPEC Process II. Adsorption of strontium and some typical co-existent elements contained in high level liquid waste onto a macroporous silica-based crown ether impregnated functional composite

Abstract

To separate Sr(II), one of the heat emitting nuclides, from high level liquid waste (HLLW), a macroporous silica-based DtBuCH18C6 polymeric composite, DtOct/SiO(2)-P, was synthesized by means of molecular modification of 4,4',(5')-di(tert-butylcyclohexano)-18-crown-6 (DtBuC H18C6) with a long-chain 1-octanol. It was performed by impregnating and immobilizing DtBuCH18C6 and 1-octanol molecules into the pores of the SiO(2)-P particles, the macroporous silica-based support. The adsorption of Sr(II) and some co-existent typical elements Na(I), K(I), Cs(I), Ru(III), Mo(VI), Pd(II), Ba(II), La(III), and Y(III) contained in highly active liquid waste (HLW) towards DtOct/SiO(2)-P was investigated at 323 K. The effects of contact time and the concentration of HNO(3) in a range of 0.1-5.0M on the adsorption of the tested metals were examined. The macroporous silica-based DtOct/SiO(2)-P polymeric composite showed strong adsorption ability and high selectivity for Sr(II) over all of the tested metals except Ba(II). The optimum acidity of Sr(II) adsorption onto DtOct/SiO(2)-P was determined to be 2.0M HNO(3). The bleeding behavior of DtOct/SiO(2)-P in aqueous phase was evaluated using total organic carbon (TOC) analysis. The content of TOC increased with increasing the HNO(3) concentration and contact time. It resulted from the decrease in the stability of the associated species, C(8)H(17)-OHaEuro cent DtBuCH18C6 formed through hydrogen binding, because of high temperature.