Abstract: In the field of thermal insulation, SiO₂ aerogel has attracted much attention because of its outstanding performance, but the high cost of organosilicon source limits its popularization and application. In order to reduce production cost, researchers have turned their attention to inorganic silicon source, but the preparation of SiO₂ aerogel using inorganic silicon source requires complicated solvent replacement. To solve the problem of solvent replacement, using coal gangue as raw material, the new type of liquid-liquid solvent displacement method combining with low temperature activation method were adopted to prepare super hydrophobic SiO₂ aerogel. The results show that when the activation temperature is 200 ℃, the gangue acid ratio is 1.0∶1.0 (ratio of solid mass to liquid volume), residue and NaOH solution ratio is 1.0∶1.0 (ratio of solid mass to liquid volume), activation conditions are the best. The prepared SiO₂ aerogel has unique three-dimensional network structure, high specific surface area (687.7 m²/g), super hydrophobicity (161.9°) and low density (0.034 g/cm³). This method provides a new idea for preparing SiO₂ aerogel from inorganic silicon source and significantly reduces the cost of preparing SiO₂ aerogel.

Key words: SiO₂ aerogel, coal gangue, liquid-liquid solvent displacement method, low temperature activation method, surface modification, atmospheric drying