Silica Aerogels and Their Application for Different Adsorption Processes

Silica monolith aerogels with different degrees of hydrophobicity by incorporating methyltrimethoxysilane (MTMS) or trimethylethoxysilane (TMES) in standard sol-gel synthesis were prepared. Excellent properties of the aerogels, obtained with the sol-gel synthesis, were preserved with supercritical drying with CO2. The degree of the hydrophobicity of the aerogels was tested by measuring the contact angle (θ) of a water droplet with the aerogel surface. The aerogels were also characterised by FTIR measurements. Adsorption capacity measurements show that silica aerogels are excellent adsorbents for different compounds dependent on its degree of hydrophobicity. Hydrophilic silica aerogels are shown to be better adsorbents of water moisture and vapours of volatile organic coumpunds from air than conventional adsorbents. On the other hand, for hydrophobic silica aerogels and mercapto (-HS) modified silica aerogels was proved that they are efficient adsorbents of organic and metal contaminants from water. Compared to the most used adsorbents granulated active carbon (GAC) and silica gel, aerogels exhibit capacities which enormous exceed that of both mostly used adsorbents.