Abstract
Rice husk is the major by-product of rice milling industry. In the present study, an optimal approach for extraction of amorphous silica from rice husk is demonstrated. The effects of leaching and rinsing treatments on the purity of extracted silica are investigated. The importance of amorphous phase of obtained silica is the reactivity of amorphous silica. Initially, rice husk was converted to ash by calcination and then the silica was extracted from rice husk ash by a proper alkaline solution. For this purpose, white ash was obtained by leaching process on rice husk and heating treatment at 700°C and then obtained white ash dissolved in alkaline solution of sodium hydroxide (2M). Subsequently, precipitation by means of hydrochloridric acid resulted in the extraction of active silica with high percentage of purity. The quality and purity of extracted silica was analyzed by X-ray fluorescence and X-ray Diffraction techniques. The advantage of applied method in the present research over the classic methods of silica production is the reduction of energy consumption, the decrease of extraction temperature and the abundance of raw materials needed for silica extraction.
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