Versatile fabrication of anisotropic and superhydrophobic aerogels for highly selective oil absorption

Abstract

Aerogels have shown great potential as oil absorbents, but they typically suffer from poor hydrophobicity and inferior mechanical property. Herein, anisotropic, superhydrophobic and superoleophilic fluorinated aerogels were prepared by directionally freeze-casting aqueous suspensions of graphene oxide and agarose in the presence of fluorine containing organosilane sol. The hydrogen bonding interactions between graphene oxide and agarose, and the directionally aligned porous structure gave the fluorinated aerogel prominent compression and recoverability properties. Due to its superoleophilicity, the fluorinated aerogel could collect a wide range of organic solvents and oils with excellent absorption capacities, which exceeded those of all cellulose-based aerogels and most carbon-based aerogels. The fluorinated aerogel also proved to be highly efficient in removing oil spills from water surface with outstanding selectivity due to its superhydrophobic and superoleophilic characteristics. Moreover, the high compression flexibility of the fluorinated aerogel facilitated fast and efficient recovery of the absorbed oil by simple mechanical squeezing, and ensured stable performance over repeated use. The present study provided a versatile method for design and fabrication of anisotropic, superhydrophobic and superoleophilic aerogels for environmental remediation and other potential applications.