Ambient pressure dried TEOS-based silica aerogels: good absorbents of organic liquids

The experimental work has been carried out to study the absorption–desorption properties of the hydrophobic silica aerogel for the application of oil spill cleanup. Aerogels were synthesized by sol–gel route prior to ambient pressure drying, by keeping TEOS:MeOH:Acidic H₂O:NH₄F:NH₄OH:HMDZ molar ratio constant at 1:16.5:0.81:0.62:0.63:0.41, respectively. The absorption of organic liquids by as-prepared aerogels has been carried out by adding the aerogel samples in organic liquid, viz. three alkanes: hexane, heptane, octane; the aromatic compounds: benzene, toluene, xylene; the alcohols: methanol, ethanol, propanol, and the three oils: petrol, diesel, and kerosene until it is totally wetted. It was observed that surface-modified TEOS-based aerogel absorbed the organic liquids and oils by nearly 12 times its own mass. After absorption, desorption time of liquids from the aerogel at various temperatures, i.e., at 30, 60, 80, and 100 °C was measured. The 50% volume shrinkage of the aerogel in case of oils and 20% in case of organic liquid was observed, after total desorption of liquids. No significant change in hydrophobicity of the aerogel was observed and it can be reused two times.