Optimization And Reactivity Study Of Silica In The Synthesis Of Zeolites From Rice Husk

Abstract

Although the chemical extraction of silica from rice husk ash (RHA) is well established; its reactivity in the synthesis of zeolites have not been studied and optimized. Due to the complex nature of silica, the extraction procedure is important in ensuring production of highly reactive silica. This paper reports on the optimization of the extraction procedure and determination of the factors that influence impurities are the factors that influence the reactivity of silica. Pure amorphous silica was obtained with RHA:NaOH ratio of 1.5 and sodium silicate concentration (measured in specific gravity) of 1.2-1.5. Reactivity rests of the extracted silica via crystallization of zeolite Y in reaction mixtures of various basicity show that pure zeolite Y was formed from the sample containing 85% Si0₂ with neutral or slightly basic property. In contrast,crystallization in the presence of silica source that is acidic containing a low percentage of Si0₂ favours the formation of zeolite P.