Technology for Obtaining Silicon Dioxide from Rice Husk Using Microwave Irradiation

Amorphous silicon dioxide was obtained by acid washing of rice husks followed by microwave irradiation. The optimal condition is a microwave irradiation power of ۷۰۰ watts and a duration of ۵ minutes, which demonstrates the effectiveness of this method in increasing acid penetration and accelerating the decomposition of organic matter in rice husks. Firing was carried out in a muffle furnace at ۳۰۰ °C, ۵۰۰ °C, and ۸۰۰ ℃ with exposure at each temperature for ۳۰ to ۶۰ minutes. The purity of the obtained silicon dioxide was assessed by the spectrophotometric method, measuring the optical density at a wavelength of ۸۱۵ nm. The yield of amorphous silicon dioxide was ۱۵.۳%, while its purity reached ۱۰۰%. When studying silicon dioxide samples, IR Prestige-۲۱ FTIR spectrometer, JSM-۶۴۹۰LV SEM (effective magnification ۳۰۰,۰۰۰) with the systems of energy-dispersive microanalysis INCA Energy and structural analysis HKL-Basic, and Drawell DW-XRD-۲۷ mini X-ray diffractometer (Cu-radiation = ۱.۵۴۰۶) were used. The FTIR spectrum of silicon dioxide (SiO₂) obtained from rice husks demonstrates its structural identity, confirmed by characteristic oscillation bands. A wide and pronounced absorption band in the region of about ۱۰۳۰ cm-۱ indicates asymmetric stretching vibrations of Si–O–Si bonds, a characteristic feature of amorphous silica. X-ray analysis shows the high degree of purity of the material, as well as the efficiency and accuracy of the applied heat treatment. This indicates that the resulting product mainly consists of amorphous silicon dioxide, which makes it promising for use in pharmaceuticals, adsorbents and nanomaterials, where uniformity of structure and large specific surface area are critically important. In general, the results show that acid treatment using microwave radiation not only accelerates the process of obtaining silicon dioxide from rice husks, but also contributes to improve its quality and energy efficiency of production.

کلیدواژه ها:

Rice husk ، Microwave irradiation ، Silicon dioxide synthesis ، SEM analysis ، XRD analysis ، Green Technology