Cost-Effective Preparation of Silica Aerogel with Excellent Porosity through Efficient Gel-Drying in a Supercritical Medium

In this study, a simple and novel supercritical dryer system was designed to drying of wet gel, aiming for the removal of the high energy-consumption equipment such as pump and strong compressor. The system is capable to provide the supercritical state in the fluid, only using the control of thermodynamic conditions. To ensure the proper efficiency of the developed dryer system, the silica aerogel was successfully derived from tetraethyl orthosilicate as starting material of silica. The amorphous phase of silica was identified by XRD analysis. The specific surface area and average pore size were measured at about 659 m2/g and 22 nm, respectively, via the BET method. The N2 adsorption-desorption isotherm curve shows the type IV isotherm, indicating the mesoporous structure with cylindrical and capillary pores. The bulk density and porosity were measured at about 0.11 g/cm3 and 95%, respectively. The TEM and FESEM micrographs indicate porous and interconnected structures along with open mesopores in the range of 10-30 nm. These results confirm the proper efficiency and performance of the designed supercritical dryer system.