Functionalized three-dimensional graphene sponges for highly efficient crude and diesel oil adsorption.

Modified Hummer's method has been used in this study to synthesize graphene oxide (GO) solution that was utilized for the fabrication of three-dimensional (3D) graphene sponges and their subsequent functionalization through a low-cost and facile vapor-based surface enhancement approach. The functionalized 3D-graphene sponge is an excellent absorbent, which can remove more than 3300 wt.% of crude oil (calculated with respect to the original sorbent mass). The functionalization of the obtained graphene sponges with trichloro (1H,1H,2H,2H-perfluorooctyl)silane enhanced their wettability properties due to the super-hydrophobic nature of the resulting materials characterized by the contact angles in water greater than 150°. Furthermore, their elastic compression modulus (estimated by conducting a series of compression tests) was about 22.3 kPa. The equilibrium modeling of the oil removal process, which was performed by plotting Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherms, confirmed the properties of the fabricated 3D graphene sponges as exceptional absorbents for crude and diesel oil, which could be attributed to the oleophilic nature of graphene. Moreover, the obtained 3D graphene sponges could be regenerated via heat treatment, which was conducted to release the adsorbed species. After five adsorption-desorption cycles, the sorption capacity of the produced 3D graphene sponges towards crude oil reached 95% of the initial value.