Mg(OH)_2の熱分解におけるHF添加の影響

概要

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The effect of HF on the decomposition of brucite was studied by differential thermal analysis (DTA) and X-ray powder diffraction (XRD) . HF was added to brucite by addition of fluoride or by treatment with hydrofluoric acid solutions. In fluoride addition, AlF_3 was more effective in retarding the decomposition of brucite than MgF_2. HF gas was formed by the hydrolysis of fluoride and then sorbed on the surface of brucite. The endothermic peak of brucite shifted to high temperature from several to about 40 degrees with increasing AlF_3 content from 0.5 to 5 mol%. Similarly, the endothermic peak of brucite treated with hydrofluoric acid solution also shifted to high temperature, about 70℃ for the specimen treated with 0.15 HF (molar ratio of HF vs. brucite) . The retardation of decomposition was due to the chemisorption of HF on the edge of brucite which would decompose from the edge.
1989-06-01