Preparation of SiO2 aerogel from rice husk ash

Abstract

Silica was leached from rice husk ash as sodium silicate by NaOH treatment. Using water glass as the silica source, SiO₂ aerogel was prepared via the sol–gel process and supercritical drying of ethanol. Based on gelation time and porous characteristics of SiO₂ aerogel, the optimum gel preparation technology was determined such as silica concentration of 6.0 wt%, gelation at pH value of 5.0 and aging in H₂O/EtOH. Incidentally, the density was as low as 0.0713 g cm⁻³, specific surface area was 729.82 m² g⁻¹, hole size was 3.39 cm³ g⁻¹, and average pore size was 16.32 nm, and the size distribution was uniform.