Preparation of SiO₂ Aerogel from Coal Gangue by One-step Acid-base Catalytic Method

Using coal gangue from Shuozhou, Shanxi as a single silicon source, superhydrophobic silica aerogel materials were prepared by acid-base one-step catalytic method. The effects of hydrochloric acid concentration and acid leaching temperature on alumina leaching, sodium hydroxide concentration and alkali leaching temperature on silica leaching, and the effects of hydrochloric acid concentration on aerogel under acid-base one-step catalysis were investigated by single factor leaching test. The results showed that: when hydrochloric acid concentration in acid leaching process was 3 mol/L, acid leaching temperature was 100 ℃, sodium hydroxide concentration was 3 mol/L, alkali leaching temperature was 80 ℃, and hydrochloric acid concentration in acid-base one-step catalytic process was 2 mol/L, the leaching rate of alumina and silica was 81.26% and 86.53%, respectively. The bulk density, specific surface area and hydrophobic angle of aerogels could be 0.04 g/cm³, 610.68 m²/g and 144.8°, respectively. This technology could provide an effective way for comprehensive utilization of coal gangue.