低温水熱反応による黒曜石からの粘土鉱物の生成 (その1) : Alイオン添加の影響

概要

論文の詳細を見る
Experimental alterations of obsidian were performed in 20, 50, and 100 ppm of AlCl_3 solutions at 150°and 200℃ for 1 to 60 days. The alteration products were examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray analysis. The surface morphology and composition of obsidian before and after alteration were examined by SEM and X-ray photoelectron spectroscopy (XPS), respectively. The pH-value of solution before reaction is approximately 2.0, and it increased progressively proceeding the dissolution of obsidian. The alteration products appeared in this reaction system were strongly dependent on pH-values of solutions. XRD and TEM showed that boehmite, spherical kaolinite and precursor of smectite exhibiting fibrous habit were mainly formed in acidic solutions. However, smectite appeared as predominant reaction product in solutions at pH > 5.0, and the spherical kaolinite began to decompose at that pH range. XPS indicated that Al-rich layer was formed on the surface of obsidian by cation exchange reaction between Si and Al in solution during the initial dissolution stage. The Al-rich layer began to dissolve into the solution with increasing pH of solutions.
日本粘土学会の論文
1993-08-31