Synthesis of silica from rice husk by sol-gel method

Abstract

Rice husk is an abundant and underutilized agricultural by-product in Indonesia. The silica contained in the waste could be used as a substitute natural silica for various purposes. The extraction of silica from rice husk (RH) has been done using the sol-gel method without involving high energy. Extraction was carried out with KOH at concentrations of 7, 10, and 13% for 90, 120, and 150 minutes. Experimental results showed that the highest extraction yield was obtained at the extraction process using KOH 7% (average 9.03%). The minimum concentration of KOH could produce the maximum yield of silica. Characterization by XRD showed that the silica had the same pattern as that of commercial products and it was categorized as amorphous silica indicated with the broad peaks at 2θ = 22°. Amorphous silica with high purity was produced from rice husk by KOH 7 % at 120 min (95.34 %). The process condition resulted in high reactivity and a high BET surface area. The washing process needs to be intensified to improve the purity of silica.