Preparation of High Grade Silica from Rice Husk for Zeolite Synthesis

Silica powder with approximately 96% purity was extracted from rice husk (RH) and used as a silica source for the synthesis of zeolite Y by hydrothermal process. The effect of synthesis parameters such as pH, temperature of burning the rice husk, acid leaching prior to formation of rice husk ash (RHA) on the properties of final product were studied. The acid-leached rice husk calcined at 650 °C for 6 h produced rough powder of rice husk silica, light brown in colour. The silica purity of the rice husk ash (RHA) calcined at 400, 450 and 500 0C were 95.6wt%, 96.1wt% and 95.89 wt% respectively. The X-Ray Diffraction (XRD) pattern of the silica obtained show that the silica was amorphous with traces of crystalline phase. The amorphous nature of the RHA and the relatively high purity of silica content in it make it a suitable source of silica for zeolite synthesis.