Natural graphite flake aerogels with synergistic photothermal conversion and thermal energy regulation for high-viscosity crude oil recovery

Oil-adsorbing materials with photothermal conversion serves as an important strategy for viscous crude oil spill cleanup, yet the application of conventional photothermal adsorbents is greatly limited by the instability of natural light irradiation. In this study, a novel type of aerogel-based adsorbent with efficient photothermal conversion and energy storage ability (Paraffin@PDMS/Fe/GCA) was fabricated through simple ambient drying strategy. Paraffin@PDMS/Fe/GCA was constructed by natural graphite flakes and cellulose nanofibrils (CNF), and then paraffin was encapsulated as phase change materials (PCM) to realize the energy storge and release. The complexation between Fe 3+ ions and the surface groups of CNF (–OH and –COOH) contributes to the stability of the 3D structure, which not only enables effective PCM encapsulation, but also resists capillary forces during the ambient drying process. This study achieves the preparation of aerogel-based phase change composites through simple ambient drying. The resulting Paraffin@PDMS/Fe/GCA exhibits remarkable photothermal performance, reaching a steady-state temperature of 77 °C under 100 mW/cm 2 irradiation, and demonstrates a high adsorption capacity for viscous crude oil. Importantly, by releasing the stored heat by paraffin, it can clean up crude oil spills on the low temperature seawater surface (near 0 °C) or under conditions of intermittent sunlight. The crude oil recovery rate of Paraffin@PDMS/Fe/GCA was 1.61 times higher than that of PDMS/Fe/GCA after two cycles of turning on and off the lights. This novel photothermal adsorbent can be produced on a large scale, and avoid the use of expensive photothermal materials, demonstrating unique advantages in the remediation of crude oil spills.