Highly Compressible and Lightweight Al₂O₃/PCNF@ANF Aerogels for Effective Oil Adsorption and Separation

Due to the lightweight feature, superior hydrophobic and oleophilic property, as well as remarkable adsorption capability, carbon-based aerogels have become appealing adsorbents for removing leaking oils and toxic organic contaminants. Herein, a highly compressible and lightweight hybrid aerogels were fabricated with organic aramid nanofibers (ANF) and inorganic Al₂O₃-doped honeycomb-like porous carbon nanofibers (Al₂O₃/PCNF) through a freeze-drying method. Thanks to the organic–inorganic hybridization approach, the optimal Al₂O₃/PCNF@ANF aerogels achieved excellent mechanical compressibility, maintaining over 95% of the compressive stress after 100 cycles with a 40% strain. Besides, benefiting from the macroscopic macro-porous lamellar structure of aerogels and microscopic hierarchical porous structure of Al₂O₃/PCNF, an extremely low density of 0.0178 g/cm³ was achieved. As oil-adsorption material, the aerogels displayed outstanding adsorption capacity for various organic solvents and oils, especially for dichloromethane of 71.8 g g⁻¹, which was as high as 72 times than the weight of original aerogels. Furthermore, the adsorbed oils or organic solvents could be recovered through simple mechanical squeezing, while maintaining a high oil-adsorption efficiency of 90.01% over 10 cycles. Moreover, it could continuously separate dichloromethane from dichloromethane–water mixture with high flux of 10,559 L^.m^−2.h⁻¹, even for surfactant-stabilized water-in-n-heptane emulsions of 5807 L^.m^−2.h⁻¹. Such a well-designed Al₂O₃/PCNF@ANF aerogels were expected to be a promising economical and efficient oil adsorption and separation material.