This study investigates the anion exchange aspects of layered double hydroxides (LDHs) consisting of Mg and Al (molar ratio of Mg and Al=2; Mg/Al(2)LDH) in MeOH. Accordingly, anion exchange experiments of Mg/Al(2)LDH with CO_3^<2->, Cl^-, or NO_3^- were performed and the isotherm curves obtained for anion exchange were analyzed by the Freundlich model. Moreover, the structural features of Mg/Al(2)LDH with CO_3^<2->, Cl^-, or NO_3^- were investigated by synchrotron X-ray diffraction at BL02B2 in SPring-8 using the large Debye-Scherrer camera with an imaging plate. The anion exchange capacity of Mg/Al(2)LDH with CO_3^<2-> for Cl^- was larger than that for NO_3^-. However, the strength of electrostatic interactions between the anion and anion exchange sites on the surface of the LDH layer show an opposite trend. The structural analysis showed that the interlayer distance of Mg/Al(2)LDH with Cl^- and NO_3^- decreased when dispersed in MeOH because of the displacement of water molecules incorporated in the interlayer of the LDH. Therefore, it was determined that the chemical state and amount of water in the interlayer is very important and largely affects anion exchange of LDHs in MeOH.

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Interstratified illite/smectite mineral was found as a clay vein in the Toyomi landslide-prone area in Kitami City, northeastern Hokkaido, Japan. The white with a slight green tint drusy interstratified illite/smectite mineral vein was observed in chaotic rock of the Nikoro Group in the accretionary Tokoro Belt. The interstratified illite/smectite mineral is associated with calcite, quartz, and chlorite. The mode of occurrence and mineral assemblage indicate that the interstratified illite/smectite mineral precipitated directly from the hydrothermal solution having a near neutral pH.

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"Geopolymer" is the general name for an alkali aluminosilicate polymer. The effects of the Si/Al molar ratio and alkali species (K or Na) on the solid-phase formation and of syneresis (water evaporation) on the formation of microporous geopolymer were investigated. The sizes of the constituent particles decreased from the micrometer to nanometer scale as the Si/Al molar ratio increased, and the decrease in particle size was accompanied by the concentration of interstitial pores approximately 50 nm in diameter between the particles. K-type geopolymer possessed an aggregated structure of small spherical particles, whereas Na-type geopolymer had an aggregated structure of large, irregularly shaped particles. The size and number of pores increased by syneresis as the water ratio increased; however, moderate syneresis decreased the size and number of pores.

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Cesium (Cs) sorption experiments were conducted using the soil of a paddy field in Fukushima, Japan, to find Cs-sorbing materials in the actual soil. The soil particles were reacted with a CsCl solution for one day, which formed a Cs concentration in the soil particles of around 150 ppm. The Cs-sorbed particles were molded into the form of a disk and Cs distribution on the disk surface was acquired using electron-probe X-ray microanalysis. The Cs-concentrated regions on the disk were further confirmed using scanning electron microscopy, and thin film specimens for transmission electron microscopy (TEM) were prepared using a focused-ion-beam instrument. TEM with X-ray microanalysis revealed that the major Cs-sorbing materials were biotite-vermiculite (B-V) mixed-layer mineral and aluminous smectite containing considerable amounts of iron. The B-V mixed layer mineral incorporated cesium ions at the interlayer regions which were probably originally hydrated ones. The structure and Cs-adsorption/desorption properties of the smectite should be investigated in future.

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