Toshitaka Kaneshiki

Separation of calcium-48 isotope by crown ether chromatography using ethanol/hydrochloric acid mixed solvent

Benzo-18-crown-6 ether resin embedded in porous silica beads was synthesized and used as the packing material for chromatographic separation of (48)Ca isotope. The aim of the present work is to develop efficient isotope enrichment process for double β decay nuclide (48)Ca. To this end, ethanol/HCl mixed solvent was selected as the medium for the chromatographic separation. Adsorption of calcium on the resin was studied at different HCl concentrations and different ethanol mixing ratios in batch-wise experiments. A very interesting phenomenon was observed; Ca adsorption is controlled not by the overall HCl concentration of the mixed solvent, but by the initial concentration of added HCl solution. Calcium break-through chromatography experiments were conducted by using 75v/v% ethanol/25v/v% 8M HCl mixed solvent at different flow rates. The isotope separation coefficient between (48)Ca and (40)Ca was determined as 3.8×10(-3), which is larger than that of pure HCl solution system. Discussion is extended to the chromatographic HETP, height equivalent to a theoretical plate.

Uranium separation from a simulant fuel debris solution using a benzimidazole-type anion exchange resin

ABSTRACT Ion exchange is one of the most useful separation methods. Certain ion exchange resins have been developed for use in reprocessing technology. The purpose of this study is to evaluate the U selectivity of a benzimidazole-type anion exchange resin and its potential for the separation of U from a solution of simulant fuel debris in HCl. The selectivity of the benzimidazole-type anion exchange resin for adsorption of the major elements present in fuel debris in HCl solution (such as in debris from the Fukushima Daiichi nuclear power plant) was analyzed, and the tendencies were discussed from the viewpoint of complexation. Moreover, chromatographic separation of U from the other elements was evaluated using the resin. The results indicate that this type of resin has high U separation selectivity. Consequently, the authors developed a novel strategy involving the use of this resin for U separation in conjunction with chlorination of hardly soluble materials by using atmospheric-pressure nonthermal plasma. This strategy is also proposed to be applicable for stabilizing waste forms and for nuclear fuel material accounting, such as for debris from the Fukushima nuclear power plant and other complex hardly soluble nuclear materials.

Adsorptivity of various metal ions onto benzo-18-crown-6 and dibenzo-18-crown-6 resins

Adsorptivity of metal ions onto silica-supported benzo-18-crown-6 (B18C6) and dibenzo-18-crown-6 (DB18C6) resins was investigated in nitric acid and hydrochloric acid media to evaluate the applicability of these resins for selective separation of nuclides from radioactive waste solutions. Both resins adsorbed Pd(II) and Ag(I) from HNO3, and Fe(III) and Ba(II) from HCl. It was also found that the B18C6 and DB18C6 resins adsorbed Sr(II) from HCl and Ca(II) from HNO3, respectively. This indicates that the two resins adsorb metal ions with smaller cationic diameters with different selectivity. This behavior is different from other impregnated adsorbents and extractants containing the 18-crown-6 moiety.