Superhydrophobic reduced graphene oxide@poly(lactic acid) foam with electrothermal effect for fast separation of viscous crude oil

Abstract In recent years, eco-friendly superhydrophobic materials have aroused much attention. Herein, biodegradable poly(lactic acid) (PLA) was selected as basic material to fabricate superhydrophobic foam with electrothermal effect by dip-coating graphene oxide (GO) on the surface of PLA foam constructed through freeze-drying process and the subsequent reduction with hydroiodic acid. Owing to the micro-nano rough structure of pristine PLA foam and the coverage of low-surface-energy reduced GO (rGO), the obtained rGO@PLA foam exhibited excellent water repellency with a high water contact angle of 150.6°. The foam was able to separate different oil–water mixtures, and the separation efficiencies were all above 96%. Importantly, the rGO layer also endowed the PLA foam with electrothermal conversion capability, and the surface temperature of the rGO@PLA foam rapidly increased to 129.5 °C from 30.8 °C at a low voltage of 15 V within only 120 s. By means of the generated Joule heat, the rGO@PLA foam was successfully applied for separating viscous crude oil from water, and the separation rate was about 14 times higher than that without voltage. Our findings conceivably stand out as a new tool to fabricate functional biodegradable materials for clean-up of viscous crude oil. Graphical abstract