SPEC Process III. Synthesis of a Macroporous Silica-Based Crown Ether-Impregnated Polymeric Composite Modified with 1-Octanol and its Adsorption Capacity for Sr(II) Ions and Some Typical Co-Existent Metal Ions

Abstract

A macroporous silica-based 4,4′,(5′)-di(t-butylcyclohexano)-18-crown-6 (DtBuCH18C6)-impregnated polymeric composite, (DtBuCH18C6 + Oct)/SiO 2 -P, was synthesized by molecular modification of DtBuCH18C6 with 1-octanol through hydrogen bonding. This was achieved by impregnating and immobilizing DtBuCH18C6 and 1-octanol molecules in the pores of macroporous SiO 2 -P particles possessing a mean pore diameter of 50 µm. The adsorption of some fission and non-fission products contained in highly active liquid waste (HLW) such as Ru(III), Mo(VI), Pd(II), Na(I), K(I), Cs(I), Sr(II), Ba(II), La(III) and Y(III) onto (DtBuCH18C6 + Oct)/SiO 2 -P was investigated at 298 K. The effects of contact time and HNO 3 concentration within the range 0.1-5.0 M were examined. Increasing the HNO 3 concentration from 0.1 M to 2.0 M led to a significant increase in the adsorption of Sr(II), followed by a decrease when the HNO 3 concentration was increased further to 5.0 M. The optimum concentration of HNO 3 in the adsorption of Sr(II) onto (DtBuCH18C6 + Oct)/SiO 2 -P was determined as 2.0 M. For the other ions examined with the exception of Ba(II), very weak or almost non-existent adsorption capacities were observed at all HNO 3 concentrations. The leaching of total organic carbon (TOC) from (DtBuCH18C6 + Oct)/SiO 2 -P into the aqueous phase was evaluated. Over the HNO 3 concentration range 0.1-3.0 M, the quantity of TOC leached was ca. 40 ppm compared with 355.8-373.3 ppm at HNO 3 concentrations above 4.0 M. Significant reduction of TOC leaching from the macroporous silica-based DtBuCH18C6-impregnated polymeric composite was achieved in 2.0 M HNO 3 . Such behaviour could be of great benefit in using (DtBuCH18C6 + Oct)/SiO 2 -P for the partitioning of Sr(II) from HLW by extraction chromatography.

Adsorption Property of Cesium onto Modified Macroporous Silica–Calix[4]arene-crown Based Supramolecular Recognition Materials

“…It was performed utilizing two novel macroporous silica-based supramolecular recognition materials: Calix[4]arene-R14/SiO 2 –P and DtBuCH18C6/SiO 2 –P. , In the first column packed with Calix[4]arene-R14/SiO 2 –P, all of the tested metals were separated to (1) Na(I), Sr(II), Ba(II), K(I), Rh(III), Pd(II), Mo(VI), Ru(III), and Zr(IV), etc. (nonadsorptive group) and (2) Cs(I) and Rb(I) (Cs group) using 4.0 M HNO 3 and water as eluents, respectively. − Subsequently, the Sr-containing effluent in the second one packed with DtBuCH18C6/SiO 2 –P was separated to (1) Na(I), Ru(III), Zr(IV), Rh(III), Pd(II), Mo(IV), and K(I) (nonadsorptive group) and (2) Sr(II) and Ba(II) (Sr group) utilizing 2.0 M HNO 3 and water as eluents. − Chromatographic partitioning of Sr(II) and Cs(I) from a HNO 3 medium was achieved preliminarily. However, the adsorption characteristics, the adsorption capacity, the evaluation of the supramolecular recognition materials modified with different organic reagents, and the effect of some factors such as temperature and the concentration of uranium on the adsorption of Cs(I) have not been understood yet.…”