SYNTHESIS OF PURE SILICA FROM RICE HUSK ASH AS AN ANTI–CAKING AGENT FOR FERTILIZER INDUSTRY IN VIETNAM

Abstract

Pure silica particles have been successfully synthesized from rice husk ash (RHA) by precipitation method. The characterization of silica was performed by X–ray diffraction, X–ray fluorescence, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller specific surface area, and transmission electron microscopy. The characterization results show that the obtained amorphous silica was 99.8 % purity with average particle size of 5–10 nm, and high specific surface area of 224 m2/g. Additionally, for the first time that RHA–silica was successfully applied as an anti–caking agent for a NPK–fertilizer. A suitable content of silica was evaluated through the level of anti–caking. The testing results show that with only 1.5 wt% of RHA–silica particles could replace kaolin as an anti–caking agent for the NPK–fertilizer.