Thermoanalytical studies on acid-treated rice husk and production of some silicon based ceramics from carbonised rice husk

Abstract

Acid pre-treatment of rice husk activated amide groups, thereby rendering the material to earlier decomposition as compared to raw rice husk when subjected to thermal analysis under non-isothermal conditions. The role of heating rate on thermal characteristics of acid-treated rice husk and energy of activation of thermal degradation were discussed in this study. The latter was dealt using Flynn and Wall equation and studied over a range of thermal destruction. Comparison of TG curves, at 5 and 10 °C/min revealed that degradation rate was faster in case of faster heating rate up to about 50% weight loss and then retarded resulting in lower final degradation temperature. It can be concluded from energy calculations that, as degradation proceeded, overall energy of activation increased up to 50% weight reduction. TG analysis was followed by high temperature pyrolysis of carbonised rice husk under argon and nitrogen atmospheres to obtain carbide, nitride, and oxynitride of silicon. Formation of different products was confirmed by FT-IR and XRD, and yield was calculated through HF dissolution method. Argon pyrolysis was proved efficient, as compared to nitrogen and closed tube pyrolysis, in yielding 30% by weight of silicon carbide from carbonised rice husk.