Preparation Of Silica From Rice Husks

Preliminary leaching of rise husks with a solution of hydrochloric acid before their combustion at 600 deg C is shown to be required to obtain relatively pure silica (~99.5%) with a high specifc surface area (~260m2/g) that is maintained even after heating at 800 deg C. Transmission electron microscopy observations indicate that this material has a homogenous size distribution of nanometric particles. However, if the leaching with HC1 is performed on the white ashes obtained by combustion of the rise husks at 600 deg C, an amorphous silica with the same purity also is obtained, but its specific surface area decreases to 1m2/g.