Study on the Preparation of TiO₂-SiO₂ Composites from Rice Husk Ash

College of Materials Science and Engineering, Beijing University of Technology, China  

Corresponding author: Xiaoyu Ma. Email: maxiaoyu@bjut.edu.cn

Abstract

In this paper, TiO₂-SiO₂ composites with different SiO₂ content s were prepared by coprecipitation method using rice husk ash as raw material. The effects of the concentration of alkaline leaching solution and reaction temperature on the extraction rate of SiO₂ from rice husk ash were investigated. The optimum formation conditions of TiO₂-SiO₂ composites were explored, and the microstructure and properties of the composites were analyzed. The experiment al results showed that the extract ion rat e of SiO₂ from rice husk ash reaches the maximum when the concentration of alkaline leaching solution is 1.5 mol/L and the reaction temperature is 90°C. When the pH value is 7, the TiO₂-SiO2 composites can achieve the optimum formation condition. TiO₂-SiO2 composites are composed of approximately spherical particles with obvious pore structure of the surface and piling up in fluffy state. The Si atoms enter the crystal structure of TiO₂ with Ti-O-Si bonds connected to Ti atoms, which inhibits the growth of TiO₂ grains and leads to the increase of the transition temperature of TiO₂ from anatase to rutile.