Utilization of Rice Husks and the Products of Its Thermal Degradation as Fillers in Polymer Composites

Abstract

Rice husks are an important by-product of the rice milling process and are a major waste product of the agricultural industry. Rice husks contain nearly 20 mass% silica, which is present in hydrated amorphous form. They have now become a great source of raw biomass material for manufacturing value-added silicon composite products, including silicon carbide, silicon nitride, silicon tetrachloride, magnesium silicide, pure silicon, zeolite, fillers of rubber and plastic composites, cement, adsorbent, and support of heterogeneous catalysts. The controlled burning or thermal degradation of the rice husks in air or nitrogen leads to the production of white rice husk ash (WRHA) or black rice husk ash (BRHA), respectively.