We attempt to prevent the release of sodium and potassium during pyrolysis and CO_2 gasification of low-rank coals using clay minerals. Although the release behaviors of alkali metals were almost the same for different coal species, the amounts of alkali metals released differed. The release extent of alkali species from Yallourn coal was higher than that from Barau coal during heat treatments. With the addition of clay minerals, the release of alkali metals was inhibited. In particular, alkali metal release was effectively inhibited during gasification. The inhibition of both the releases of sodium and potassium could be sufficient with the addition of 10wt% kaolinite sample during the heat treatment, while the inhibition of the release of alkali metals with the addition of 10wt% pyrophyllite sample was not confirmed. As a result, kaolinite could be used to inhibit alkali metal release from coal during coal conversion.

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We attempted to make agricultural cultivation solution from seawater with a two-step process using calcined hydrotalcite and natural zeolite. Commercial calcined hydrotalcite was used in first step to reduce Cl^- content in seawater. Two types of Japanese natural zeolite, mordenite-type zeolite (Iizaka mine, Fukushima prefecture) and clinoptilolite-type zeolite (Koriyama mine, Kagoshima prefecture) were used in second step to reduce Na^+ concentration. Cl^- in seawater can be reduced by calcined hydrotalcite to obtain anion-reduced solution; Na^+ can be reduced by ion exchange with both types of natural zeolite. The obtained solution was neutral, and included the nutrients K^+, Mg^<2+>, and Ca^<2+>, and low levels of Na^+ and Cl^-. Higher concentrations of K^+, Mg^<2+> and Ca^<2+> in the solution can be obtained by mordenite-type Iizaka natural zeolite than those by clinoptilolite-type Koriyama natural zeolite. Radish sprouts did not grow in seawater and anion-reduced solution, but they grew in both solutions after zeolite treatment.

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In the present study we describe the surface etching features of plagioclase, pyroxene, olivine, amphibole, and biotite phenocrysts in tephras from Hachijo-Higashiyama, Daisen, and Niijima volcanoes with progress in weathering. The variations in the size and number of etch pits were quantified by image analysis as a function of depth in tephra column from Hachijo-Higashiyama. In Hachijo-Higashiyama tephras, pyroxene and plagioclase phenocrysts were completely covered with glassy materials and etching did not occur during the early weathering duration of about 10ky after deposition. After the glassy cover disappeared, etching began selectively at dislocations. The etch-pit shapes are crystallographically controlled on different faces, particularly in plagioclase. The etch-pit density decreased, the size increased with increase in depth of tephra column. This change is an overall result of etch-pit coalescence and neoformation of small etch pits. Eitching of phenocrysts is preceded by halloysitization of glass, which results in the increase of saturation levels in porewaters infiltrating through tephra column. Consequently, it is implied that mineral dissolution rates are strongly controlled by the saturation level of porewaters with respect to solute species supplied from rapid dissolution of glasses during chemical weathering of tephras.

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Breakdown of soil aggregates by wetting is caused by air slaking (disaggregation by compression of an entrapped air inside the aggregates), swelling and dispersion of clays contained in the aggregates. Recent studies have attempted to clarify the relative importance of these mechanisms using the aggregates from cultivated fields, however, it appears that diversity and impurity of the cultivated soil have caused inconsistent results. In this study, aggregates made of pure materials (Na-bentonite and Na-kaolinite) were used to clarify the relative importance of air slaking and swelling/dispersion on the aggregate breakdown. To separate the effect of an entrapped air and electrolyte (NaCl) concentration on breakdown process, aggregates were enclosed in glass ampules under vacuum and atmospheric conditions and were subjected to sudden wetting in a series of NaCl solution. Breakdown pattern and time for breakdown were determined by visual observation. The results show that for aggregates of Na-bentonite, breakdown pattern and time for breakdown were strongly dependent on NaCl concentration, but not on air condition. The lower the NaCl concentration was, the more the aggregates dispersed and the longer the time for breakdown was. This dependency was consistent with the findings of the interlayer expansion of Na-montmorillonite in the past study. In contrast, aggregates of Na-kaolinite wetted in vacuum were not broken, whereas aggregates were quickly broken down into small pieces in the presence of the entrapped air irrespective of NaCl concentration. In conclusion, this study clearly demonstrates that the dominant breakdown mechanism of aggregates with swelling clay was dispersion/swelling and that of aggregates with non-swelling clay was air slaking.

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Luminescence quenching of tris(2,2'-bipyridine)ruthenium(II)-saponite film by sulfur dioxide is reported. The film was prepared by the ion exchange reactions of tris(2,2'-bipyridine)ruthenium(II) dichloride with Zn(II) exchanged saponite film. The change in the luminescence intensity was reversible upon the contact and the removal of sulfur dioxide, suggesting energy-transfer from tris(2,2'-bipyridine)ruthenium(II) in the saponite film to sulfur dioxide to deactivate the excited state of the dye.

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As described in this paper, the intercalation behavior of 5-fluorouracil (5-FU) into Mg-Al layered double hydroxide (LDH) was investigated using coprecipitation and ion-exchange methods. Actually, 5-FU/LDH has been characterized using element chemical analysis, powder X-ray diffraction, FT-IR spectroscopy, thermal analysis and SEM. Intercalation of 5-FU was achieved using both methods; the amount and orientation of 5-FU intercalated differed considerably by the intercalation method and co-existed anion. The d-value of 5-FU/LDH expanded to d_<003>=0.80-1.10nm, suggesting that 5-FU was intercalated into the LDH interlayer space. Results of the thermal analysis showed that the thermal stability of 5-FU was improved by intercalation in the LDH interlayer space. We propose LDH as a good host material for storage and carriage of drugs.

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