Separation of trivalent actinides from lanthanides by using R-BTP resins and stability of R-BTP resin

Abstract

For the development of advanced aqueous reprocessing system, it is one of the most important subjects to separate minor trivalent actinides (MA = Am and Cm). MA are α-emitters with long half-life, therefore it is desired to separate MA from fission products. However, it is very difficult to separate MA from lanthanides (Ln) owing to their chemical similarity. For the separation of these two groups of elements, solvent extraction process has been widely studied based on the difference in complex formation with extractants. Extraction chromatography is one of the most promising separation techniques for recovering small amounts of target components from solution. For this purpose, we prepared novel silica-based extraction resins by impregnating some R-BTP molecules into a macroreticular styrene–divinylbenzene copolymer which is immobilized in porous silica particles with a mean diameter of 50 μm. The impregnated resin has high affinity for Am against Ln(III) not only in sodium nitrate solution but also in nitric acid solution. Stability of the extraction resin was also examined. The silica-based support was significantly stable against γ-irradiation and nitric acid. A part of R-BTP was dissolved into nitric acid solution from the extraction resin due to protonation. However, the branched R-BTP ( iso-Bu-BTP) resin was much more stable than a normal R-BTP in nitric acid solution (≤3 M).