Effects of calcination parameters on the silica phase of original and leached rice husk ash

This paper presents a contribution to the study of the effects of calcination parameters, including temperature and time, on the silica phase of original and leached rice husk ash. X-ray diffraction (XRD) analysis reveals the presence of totally crystalline silica in the original rice husk ash prepared at 800 degrees C. Fortunately, no indication of the presence in crystalline phase is found in the leached rice husk ash due to leaching. However, specific surface area analysis indicates that the high calcination temperature or the long calcination time renders the amorphous silica in the leached rice husk ash less activity. Therefore, the leaching procedure, the low calcination temperature and the short calcination time are proposed in order to prepare more active amorphous silica from the rice husk. (C) 2011 Elsevier B.V. All rights reserved.