Flash Dehydroxylation of Montmorillonite

P(論文)The effect of flash decrease of pressure on the dehydroxylation process of montmorillonite (Yamagata Prefecture, Japan) was studied. The experimental technique based on flash dehydroxylation means that the sample under atmospheric pressure was transferred to vacuum in a moment. The properties of flash dehydroxylation sample and the heating samples under constant pressure were investigated by means of X-ray, DTA, TG, and IR, etc.. The dehydroxylation temperature of lattice water was shifted to lower temperature with the decreasing pressure. The time for diffusion process of water molecules accompanied with dehydroxylation was rapidly redued below 100 mmHg. The basal spacing of two heating samples under constant pressure gave 9.73A and that of flash dehydroxylation sample gave 9.60A. The gap of 0.13A might depend on the different shift of potassium ion situated between the crystal layer. Namely, the exchangeable cation which occupied the space between the crystal sheets just before dehydroxylation shifted into vacant space in silicon-oxygen sheet which had come from dehydroxylation by means of flash pressure change. New pattern of 20-26A were appeared in X-ray diffraction of flash dehydroxylation samples prepared by alkali-treatment. The influence of the water molecules diffusion on crystal structure of montmorillonite might be minimized by flash change of pressure.departmental bulletin pape