Using bagasse ash as a silica source when preparing silica aerogels via ambient pressure drying

Silica aerogels were prepared using bagasse ash as a silica source through a route involving the surface modification of wet gels and ambient pressure drying (APD). The silica in the bagasse ash was extracted using a NaOH solution to form the sodium silicate precursor for the silica aerogels. Trimethylchlorosilane (TMCS) and hexamethyldisalazane (HMDS) were used to replace the surface silanol groups with alkyl groups to prevent the condensation and shrinkage of the gel structure during APD. The prepared silica aerogels exhibited strong hydrophobicity. The silica aerogels aged in water possess a higher surface area than those aged in hexane. The mixing time for the silylating agents with the silica precursor influences the surface area of the silica aerogels. The highest surface area and pore volume of the silica aerogels were 1114 m²/g and 2.16 cm³/g, respectively.