Supercritical CO₂ drying of pure silica aerogels: effect of drying time on textural properties of nanoporous silica aerogels

Aerogel technologies provide high-performance lightweight materials with unique textural characteristics such as high specific surface area and open porosity. The complete removal of liquid solvent from the wet gel without crumpling the delicate nanoporous texture is one of the significant challenges during the synthesis of aerogels. In this avenue, inspecting the effect of drying time on textural properties is conceived as a noteworthy aspect in the design and development of aerogel-based systems. Therefore, the influences of pressure and temperature on drying time during supercritical CO₂ drying were investigated in this report. Results revealed that at a fixed temperature of 40 °C, the drying time was shortened significantly with increasing pressure. When the temperature and pressure were 40 °C and 25 MPa, respectively, the 60 min of drying time was adequate to completely remove the ethanol from the silica aerogel monolith, while the structure of silica aerogel remained intact. Extending the drying time from 60 to 120 min did not make any difference in terms of the silica aerogel textural properties. In conclusion, this new approach sheds light on solving the big issue of the drying time required for the complete removal of ethanol from the silica aerogel in practical application on a large scale. [Figure not available: see fulltext.].