Layered Silicate Machinery Activated Leaching Preparation Of Porous Materials

Porous material is of importance for many scientists in domestic and abroad because of its special structure and property. It was been mainly used catalyzing, oil and chemistry, environment protecting, and so on. Porous material is traditionally prepared by hydrothermal synthesis and sol-gel method using organic silicon and silicon sol as raw materials, and these methods are difficult to widely apply, because of expensive raw material and pollution. Mechanical activation and subsequent leaching is a novel and rapid developing method to prepare porous material because of its many advantages, such as cheap raw materials, and simple process easy to control.In this paper, we reported the preparation of porous silica using mechanical activation and subsequent leaching from layer silicate, such as kaolin, illite, talc and pyrophyllite. It was characterized by XRD, IR and SEM technigues. The results indicate that grinding destroyed the structure of mine crystal and the hydroxyl of layer, and reduced the particle size of powder. Plenty of activated points can be form on the surface of powder. We also did leaching technics experiment of pure talc from guangxi in this paper, and obtained the best leaching technics conditions of talc as follows: grinding time is 4 to 6 hours, concentration of hydrochloric acid is about 4mol/L, temperature of leaching is 60 to 80℃, time of leaching is about 1 hour and the ratio of hydrochloric acid volume and sample weight doesn't exceed 20ml/g. The result of pore property indicated that our porous material possessed pore like gaps, and had two peaks in its pore size distribution curve respectively in microporous and mesoporous sections. The products from kaolin and illite have better pore property, and their pore volume and specific surface area overcome respectively 0.3ml/g and 300m~2/g. At the same time we found the leaching activation energy of talc and kaolin descended consumedly after mechanical grinding. When the original of talc and kaolin were leached, the leaching was controlled by chemistry reaction. And when the samples were ground 4 hours, diffusing course was primary in leaching. These showed mechanical grinding had prominent activation effect on leaching of layer silicate.