Extraction of Silica From Micro-silica and Preparation of Silica Aerogels
摘要
The choice of silica-based precursors has an important impact on silica (SiO2) aerogel materials. The main objective of this study is to explore a new route for the preparation of SiO2 aerogels using micro-silica. Firstly, the difference in silica extraction rate between micro-silica and quartz and analytically pure SiO2 under different conditions, and analyzed the reasons for the difference from the aspect of raw materials. Secondly, the SiO2 was extracted by a low-temperature alkaline melting method using micro-silica as the silicon source, avoiding the disadvantages of the fire method and the wet method, and the SiO2 aerogel was synthesized by drying under atmospheric pressure. The result shows the extraction rate of micro-silica was up to 94.2% comparing with the quartz and analytically pure SiO2. It found that a high extraction rate and modulus of silica resources could be obtained at a mass ratio of NaOH to micro-silica of 1.4, a calcination temperature of 450 °C, and a calcination time of 60 min. The prepared SiO2 aerogel had a typical nanoporous structure, with a density of 0.1421 g/cm3, a specific surface area of 236 m2/g, a porosity of 93.54%, and a thermally stable temperature of 400 °C, under 800 °C, the aerogel skeleton structure remains unchanged. This study gives a new way for exploring the high-value utilization of industrial solid waste.