Silica Extraction from Rice Husk: a Review on the Effect of Combustion Temperature

Abstract

Combustion significantly contributes to pollution, releasing harmful pollutants that can have detrimental effects on environmental and human health. Rice husk (RH), a by-product of rice milling, makes up about 20-22% of the weight of harvested rice. It primarily consists of cellulose, hemicellulose, lignin, and a significant amount of silica. Traditionally seen as agricultural waste and often burned or discarded, rice husks have recently gained attention for their potential in industrial applications, especially for extracting silica. This review studies the effect of the chemical composition and properties of rice husks, focusing on the combustion used to obtain high-purity silica. It reviews how the combustion temperature, heating rate, and cooling rate influence the purity and phase of silica, highlighting the delicate balance required to produce either highly reactive amorphous silica or crystalline forms of silica. Additionally, will discuss the applications of both amorphous and crystalline silica across various industries, including construction, electronics, and agriculture, showing the sustainability and economic benefits of utilising rice husk-derived silica. By optimising the combustion process, we can improve the quality and functionality of the extracted silica, thus contributing to waste reduction and environmental sustainability.