Effect of Silylating Agents on the Properties of Corn Husk–Derived Silica Aerogels Prepared via Ambient Pressure Drying

ABSTRACT

Silica content in corn husk waste can be used as a cost‐effective raw material for silica aerogel production. In this study, silica aerogels were synthesized using sol‐gel and cation exchange methods under ambient pressure drying conditions. The hydrogel was modified with hexamethyldisilazane (HMDS), polydimethylsiloxane (PDMS), and methyltrichlorosilane (MTCS) as silylating agents. This study investigates the physical, thermal, optical, and hydrophobic properties of the silica aerogel. Characterization was carried out using Fourier transform infrared spectroscopy (FT‐IR), X‐Ray diffraction spectroscopy (XRD), Brunauer‐Emmett‐Teller (BET) surface area analysis, field‐emission scanning electron microscopy (FE‐SEM), and ultraviolet‐visible diffuse reflectance spectroscopy (UV–vis DRS). FT‐IR spectra confirmed the presence of alkyl groups on the aerogel surface, while the broad diffraction peaks observed in the XRD pattern indicated the amorphous nature of the silica aerogels. FE‐SEM images revealed a nanoporous network composed of microscale particles. Hydrophobicity evaluation using water contact and sliding angle measurements demonstrated that the silica aerogel was hydrophobic, with a contact angle of 142.1° and a sliding angle of 11.05°. The synthesized aerogels exhibited a low bulk density of 0.3178 g/cm ³ , a high specific surface area of 497.0138 m ² /g, an average pore diameter of 7.9681 nm, low thermal conductivity of 0.0285 W/m.K, and a high optical transmittance of 82.8%.