Preparation and Characterization of Nanoporous Silica Aerogel Granules on The Basis of Water Glass Via Ambient Pressure Drying Method

A crack-free silica aerogel monolith is a nanostructured material with so many surprising properties such as high specific surface area, high porosity, low dielectric constant, low density and outstanding heat insulation properties that were fabricated from a cheap water glass derived silicic acid solution.In this research , the OH surfaces of the wet gel were modified using a HMDZ/n-hexane or TMCS/n-hexane mixture followed by solvent exchange from water to n-hexane. The obtained surface modified wet gel was dried at different temperature under ambient pressure.The properties of hydrophobic silica aerogels synthesized by this new route were investigated by scanning electron microscopy (SEM), differential temperature analysis (DTA) and Fourier-transform infrared spectroscopy (FT-IR).The results showed that 20 wt% HMDZ as surface modifier and 75 °C as drying temperature resulted an acceptable hydrophobic silica aerogel with the density of 0.15 gr/cm³ and specific surface area of about 520 m²/gr.