As a fundamental study on the reprocessing of spent nuclear fuel by ion exchange method, silica-based anion exchangers of about 50μm in particle size with tertiary and quaternary pyridine groups were synthesized. Adsorption and elution behavior of Pd and Ru in nitric acid medium was examined experimentally. Furthermore, column separation experiments were carried out on the simulated spent fuel solution containing U (VI) and some typical fission product elements. The adsorption of Pd (II) and Ru (III) onto the anion exchanger with quaternary pyridine group, SiPyR-N4, showed rapid kinetics and was considered to result from the anion exchange reaction of the nitrato-complexes of these metals. On the other hand, the anion exchanger with the weak-base group of tertiary pyridine, SiPyR-N3, showed significantly strong adsorption for Pd (II) and the adsorption was presumed to be caused by the complex formation reaction between Pd (II) and the nitrogen atom in the functional group. Palladium ion adsorbed on SiPyR-N4 was effectively eluted out by using ethylenediamine as an eluent, while the elution of Pd (II) from SiPyR-N3 was very difficult. The separation experiments using SiPyR-N4 packed column demonstrated that U (VI) was successfully separated from most fission product elements. However, a part of the light rare earths such as Nd and a small amount of Ru mixed in the U product solution. Pd was strongly adsorbed on the SiPyR-N4 and it was finally eluted off by using the solution containing ethylenediamine.

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The soft chemical approach to synthesis and control of the properties for functional inorganic materials by using ionexchange reactions of layered manganese oxides and layered titanates were reviewed. The metal ion templates can be intercalated into the layered manganese oxides by ion-exchange reactions. The layered structure of the manganese oxide transforms to tunnel structure under hydrothermal conditions, and the tunnel size is dependent on the size of the template ions in the interlayer space. Eight types of tunnel manganese oxides have been obtained by using this method. The tunnel manganese oxides show excellent ion-sieve properties. The sandwich layered compounds can be prepared by polymerizing ions in the interlayer space, and also by exfoliation-restacking reaction of the layered compound. The BaTiO₃ and TiO₂ with the desired morphology can be synthesized by topotactic structural transformations from the layered titanates. Furthermore, BaTiO₃ and TiO₂ thin films with crystal-axis preferred orientation can be prepared on the polycrystalline substrates by utilizing the exfoliation-restacking reaction and the topotactic structural transformation reaction.

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NMR methodologies for characterizing exactly nano-scale structure and dynamics of soft polymers such as polymer gels and polymer liquid crystals, and hard polymers such as solid organic polymers and inorganic polymers by using field-gradient NMR, three-dimensional NMR imaging and solid state NMR and its application have been viewed.

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[in Japanese]

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