Thermal behaviors of rice husk were determined by thermo gravimetric analysis (TGA) and are shown in Figs. 3 and 4. It is observed an increase in the thermal stability of the leached rice husk. Untreated agulhinha and cateto rice husk starts to thermally degrade (T1) at 168 ◦C and 173 ◦C, respectively, while leached rice husk have T1 in the range of 184–209 ◦C, another parameter that indicates the increase of thermal stability of the treated rice husk is T2, which increased about 10% or more for the treated rice husk (Table 2). This occurred due to the removal of impurities with less thermal stability. The increase in temperature from room temperature to about 200 ◦C resulted in weight losses in a range of 5.4–8.6%, depending of the rice husk variety and chemical treatment due to the loss of water present in the samples and external water bounded by surface tension. Fig.