能登珪藻土の水蒸気吸着特性に及ぼす加熱処理の影響

抄録

In order to elucidate the heat treatment effects on water vapor adsorption properties of Noto-diatomaceous earth (Noto-DE), the specific surface area (SSA) was measured with N₂ and H₂O, and pore size distribution and water vapor adsorption of the samples were also measured. Particles ＞75 µm and ＜ 2 µm in size were separated from the samples of Noto-DE and they were calcined at various temperatures up to 1,000°C. Both particles ＞75 µm and ＜2 µm showed that the SSA values measured with H₂O were larger than those with N₂. This may be caused by the chemical adsorption action on silanol radical of diatomaceous shell and the interlayer of clay minerals. Concerning samples after particle-size classification, fraction having particle size not greater than 2 µm showed the most water vapor adsorption. This result indicates that the clay minerals that account for ca. 40% of Noto-DE have a great influence on water vapor adsorption properties. Furthermore the reason why water vapor adsorption of Noto-DE decreased sharply at heat treatment above 800°C may be due to change of structure of montmorillonite. Therefore it was found that the changes in the water vapor adsorption properties of Noto-DE by heating were caused by the changes in the crystalline structure of montmorillonite.