Nanosilica from rice husk: Extraction and characterization

Rice husk are generated from the rice cultivation. Silica is the major inorganic constituent of the rice husk, and by carrying out an acid chemical treatment followed by the process of burning, it is possible to extract high-surface area amorphous silica. This paper reports the extraction and characterization of nanosilica from two types of rice husk, namely agulhinha and cateto, using milder acid solutions. Thermogravimetry was used to characterize the burning behavior and to determine the activation energies. FT-IR results showed a good peak correlation between the commercial silica and burnt rice husk residue. There were found both nano- and microparticles with a large particle size distribution. The results showed the potential of silica extraction from rice husk, and additionally exhibited lower levels of corrosion damage to the reactor that generated weak acid residues due to the use of milder acid solutions.

► We extracted amorphous white silica from rice husk using mild acid solutions.
► We have found both micro and nanostructure.
► Temperature of achievement of silica was less than 600 °C.
► We determinate activation energies of rice husk combustion process.