A robust salt-tolerant superoleophobic chitosan/nanofibrillated cellulose aerogel for highly efficient oil/water separation

Marine pollution caused by frequent oil spill accidents has already produced catastrophic influence on marine ecological environments. Even though traditional superhydrophobic/superoleophilic surface-coated materials have demonstrated to be effective for oil/water separation, they still suffer from complicated fabrication procedures, mechanical damages and loss of their superoleophobicity in high-salinity environments. Herein, a robust salt-tolerant superoleophobic aerogel was introduced for highly efficient oil/seawater separation, which was fabricated by incorporating nanofibrillated cellulose (NFC) into chitosan (CS) matrix through freeze-drying method. The NFC-reinforced 3D interconnected network structure guaranteed the mechanical performance of the CS/NFC aerogel. Together the inherent hydrophilicity of chitosan with the rough microstructure of the aerogel, excellent underwater superoleophobicity was developed. Notably, the CS/NFC aerogel still maintained its underwater superoleophobicity even after being soaked in high-salinity seawater for 30 days. Moreover, the as-prepared aerogel was able to achieve various kinds of oil/seawater mixtures separation with high efficiency (> 99%) and outstanding recyclability (at least 40 separation cycles). These excellent properties combined with its facile fabrication process make it a promising candidate for oil/water separation in marine environments.