Formation of silicon carbide from rice husks using enzymatic methods for carbon control

Abstract

A method employing cellulase treatment was developed to control excess carbon for silicon carbide formation from rice husks. Powdered rice husks were delignified with NaOH solution and treated with a mixture of cellulases (Acucelase and Meicelase) to hydrolyze the cellulose of the husks. In rice husks pretreated with 0·5% NaOH, silica was enriched to 29·5% (w/w), and 288 mg of sugar was recovered from 1·0 g of rice husks after 5-days cellulase treatment. The C/SiO 2 ratio reached 0·74, near the optimum ratio for silicon carbide formation. When this silica-enriched sample was heated at 1600°C in an atmosphere of argon, α-SiC and βSiC were formed and matured SiC whiskers were evident. Residual free carbon in the product was 1 5 of heat-treated silica sand mixed with petroleum coke and was 1 11 of rice husk heat-treated without enzyme treatment.