A green route to preparation of silica powders with rice husk ash and waste gas

The objective of the present work is to develop a green procedure for preparation of silica powders from rice husk ash (RHA) via a carbonation route. The raw materials, RHA and waste gas, were obtained from the power plant. Na2CO3 was used as the silica extraction reagent and waste gas was the precipitator. The silicon dioxide extraction yield reached 72.52% and was affected by impregnation ratio, concentration of Na2CO3 solution and reaction time. The microstructures of the as-obtained silica powders were characterized by X-ray diffraction (XRD) and infrared spectra (IR). The mineral contents of RHA and product were investigated by inductively coupled plasma (ICP) emission spectroscopy. In the whole silica extraction process, extraction reagent can be reused through appended a small quantity of Na2CO3 to its initial concentration. The synthetic procedure is straightforward, inexpensive and environment-friendly, which was suitable for large-scale production.