Simplified Synthesis of Spherical Silica Microparticles from Rice Husk

Abstract A facile synthetic method for preparing spherical silica microparticles from rice husks was developed. Spherical silica particles with an overall size of several micrometers were obtained via direct extraction of silicate solution from rice husks, followed by precipitation of silica using nitric acid and a polymer additive. The synthetic process was simplified by omitting the acid leaching and pyrolysis processes of the rice husks. Herein, it was demonstrated that the extraction of silicate under mild conditions, combined with the use of a polyethylene glycol additive during the precipitation step, are crucial for obtaining spherical silica microparticles. Moreover, the porosity of the silica particles could be controlled by adjusting the calcination temperature.