Evaluation study on properties of isohexyl-BTP/SiO2-P resin for direct separation of trivalent minor actinides from HLLW

In order to develop a direct separation process for trivalent minor actinides from fission products in high level liquid waste (HLLW) by extraction chromatography, a novel macroporous silica-based 2,6-bis(5,6-di iso hexyl)-1,2,4-triazin-3-yl)pyridine resin ( iso hexyl-BTP/SiO 2 -P resin) was prepared. The content of iso hexyl-BTP extractant in the resin was as high as 33.3 wt%. The resin exhibited much higher adsorption affinity for Am(III) in 2–3 M (mol/L) HNO 3 solution over U and FP which are contained in HLLW. The kinetic data were analyzed using pseudo-second-order equation. The results suggested that the Eu(III), Gd(III), and Dy(III) adsorption was well explained by the pseudo-second-order equation. Quantitative desorption for adsorbed elements was achieved by using H 2 O or thiourea as eluting agents. However, the kinetics of adsorption and desorption were rather slow and this drawback needs to be resolved. Stability of the resin against HNO 3 was also examined. It was found that the resin was considerably stable against ≤4 M HNO 3 solution for the reasons of an extremely small leakage of the extractant into the solution from the resin and the adsorption performance keeping for rare earths in 3 M HNO 3 solution.