Superhydrophobic Kapok Fiber-Based Aerogels for Efficient Photothermal-Assisted Crude Oil Adsorption

Marine oil spill remediation of high-viscosity crude oil remains a formidable challenge due to the sluggish infiltration kinetics of viscous pollutants. Herein, a sustainable and superhydrophobic CKF/KCN composite aerogel was engineered by integrating carbonized kapok fibers (CKF) into a kapok cellulose nanofiber (KCN) matrix via directional freeze-casting and silane modification. Leveraging the intrinsic hollow tubular structure of biomass kapok fibers and the broadband light absorption (96.3%) of the CKF skeleton, the CKF/KCN aerogel achieves efficient photothermal conversion. Under 1 sun illumination, the aerogel surface rapidly reaches 75.8 °C within 10 min, triggering a localized dramatic viscosity reduction across the pour point that reduces crude oil viscosity to below 5.3 mPa·s. This thermal-assisted mechanism enables the aerogel to achieve a high sorption capacity of 98.4 g g -1 and facilitates rapid oil uptake within 60 s, which is 7.4 times faster than non-photothermal counterparts. Furthermore, the aerogel exhibits excellent mechanical robustness and cyclic stability, retaining 74% of its initial capacity after 20 sorption-squeezing cycles. This work provides a green and high-efficiency strategy for the recovery of viscous crude oil spills using functionalized agricultural waste.