Changes in Rice Husk by Heat Treatment

The effects of heat treatment conditions on the properties of rice husk were evaluated in this study. The commercial products of the heat treated rice husk were also investigated in terms of the changes in the properties by the manufacturing methods such as the indirect rotary kiln method and the direct combustion method. The indirect rotary kiln treatment for the commercial product resulted in the lower carbonization and the lower absorption of methylene blue of the heat treated rice husk product than those of the direct heat treated rice husk product. In addition, the effect heat treatment was analyzed under two different conditions - by using muffle furnace at air atmosphere condition and by using tube furnace at nitrogen atmosphere condition - for comparative analysis. The rice husk treated in nitrogen condition showed less carbonation, less changes in pH and no significant changes in methylene blue absorption properties, compared to the rice husk treated in the air condition. The pH of the rice husk treated in the air condition changed from 3.5 at 300°C treatment to 9.5 at 500°C treatment. Also, the absorption capacity of the rice husk treated in the air condition was greatly improved as the treatment temperature increased.