Hydrophobic and nanoporous chitosan–silica composite aerogels for oil absorption

Hydrophobic and nanoporous chitosan-silica composite aerogels with low density, high porosity, and superior oil absorbency were successfully prepared by a typical sol-gel method and a two-step hydrophobic treatment. The morphologies, porosity characteristics, mechanical properties, thermal stability, hydrophobicity, and oil absorbencies of the composite aerogels were systematically investigated. The nitrogen physisorption analysis showed that composite aerogels had large specific surface areas and uniform nanoporous structures. In addition, the composite aerogels could support 7000 times its own weight; this indicated the role of the supporting skeleton played by chitosan. The hydrophobicity and lipophilicity was demonstrated with a water contact angle of 137 degrees and an oil contact angle of 0 degrees. Importantly, the composite aerogel with 20 wt % chitosan had a relatively high oil absorbency of 30 g/g and could be reused up to 10 times. Therefore, the chitosan-silica composite aerogels in this study had a broad prospect to be used as efficient and recyclable oil absorbents. (C) 2014 Wiley Periodicals, Inc.