Graphene aerogels as oil adsorbents

Oil spills are a growing threat to the environment and human health. With increased consumption of fossil fuels, millions of gallons of crude oil are spilled over oceans every year. Current oil spill clean-up techniques can be expensive or even the source of other types of pollution. Oil adsorbents have gained popularity due to their potential to be low-cost, environmentally friendly, reusable, oleophilic, and hydrophobic. Aerogels, highly porous and low-density materials, have shown great promise as oil adsorbents. In this study, the adsorption and reusability of graphene aerogels prepared via different methods was investigated. Using graphene oxide and one of two reducing agents (either 1-octadecylamine or ascorbic acid), a reduced graphene oxide wet gel is obtained. Following solvent exchanges, these wet gels are then processed to remove the solvent by either rapid supercritical extraction (RSCE) or freeze-drying, to yield monolithic aerogels. The density of the aerogels ranges from 6 mg/mL to 18 mg/mL. In 30 min, the RSCE aerogels prepared using octadecylamine adsorbed up to 61,000 mg/g and the aerogels prepared using ascorbic acid adsorbed up to 15,000 mg/g. The freeze-dried aerogels adsorbed up to 99,000 mg/g of mineral oil in 30 min. The materials were also characterized using infrared spectroscopy and scanning electron microscopy. Additional physical characterization of the aerogels, detailed oil adsorption studies (including reusability), and comparison of aerogels prepared with different reductants and different processing methods will be presented.