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Improvement of the characteristics of silica particles extracted from rice husks using chemical-physical method

Silica (SiO2) can be extracted from rice husks and has biodegradable properties. However, the rice husk extraction process using the sol-gel technique generates low-purity silica, making them non-compliant as a filler material on the rubber finished goods industry. This study aimed to improve the characteristics of silica particles extracted from rice husks using the leaching-pyrolysis technique compared to the sol-gel technique. Silica was extracted from rice husks using 1.0 N sodium hydroxide and hydrochloric acid solvent (with concentrations of 0.4 N, 1.0 N, and 2.0 N). The pyrolysis was then conducted at 600 °C for 6 hours. The results showed that the leaching-pyrolysis technique was more effective than the sol-gel technique in improving silica particle characteristics. X-ray fluorescence analysis showed that the SiO2 content increased from 91.00 % to 96.82 %. Likewise, the percentage of amorphous by X-ray diffraction analysis and specific surface area by the Brunauer Emmett-Teller method also increased, namely from 48.20 % to 53.97 % and from 96.486 m2/g to 240.427 m2/g, respectively. Therefore, silica from rice husks with these characteristics is applicable as a filler material that is environmentally friendly and renewable.