TEMPO-doped PDA/nanocellulose photothermal hydrophobic aerogel and its continuous absorption for high viscosity crude oil

Using in situ solar-driven self-heating materials to improve the absorption efficiency of crude oil is one of the common strategies for cleaning up offshore oil spills. To increase the photothermal conversion efficiency of polydopamine (PDA), O-PDA doped with 2,2,6,6-tetramylpiperidine oxide (TEMPO) was prepared as a photothermal component and loaded on straw-based nanocellulose fibrils (LCNFs). The composite hydrophobic aerogel M-LOPA with enhanced photothermal effect and high oil absorption was constructed by freeze-drying and MTMS chemical deposition. The microstructure, wettability and photothermal conversion performance of the three aerogels with non-photothermal component, PDA and O-PDA as photothermal components were compared. The results showed that the absorption capacity of M-LO₂PA (TEMPO∶DA = 1.5∶1) to organic solvent and light oil could reached 30.2-75.5 g/g. Under a solar radiation intensity (1 kw/m²), the surface temperature of M-LO₂PA rose to 52.8℃ within 6 min, which was 57% and 21% higher than that of the aerogel without photothermal component and with PDA as the photothermal component, respectively. The absorption capacity of M-LO₂PA for high viscosity crude oil reached up to 46.2 g/g and realize the continuous separation of high-viscosity crude oil from water surface by in situ pumping under the simulated sunlight irradiation, which has certain application in cleaning and recovery of offshore oil spills.