Hydrophilic and Underwater Oleophobic Chitosan/Polyvinyl Alcohol/Cellulose Aerogel for Efficient Oil/Water Emulsion...

Oily wastewater, especially stable oil-in-water (O/W) emulsions, threatens aquatic ecosystems and is difficult to treat using conventional separation technologies. Herein, a hydrophilic and underwater oleophobic chitosan/polyvinyl alcohol (PVA)/cellulose aerogel (CPCG) was fabricated through a facile one-pot dip-coating strategy. Cellulose aerogel (CG) was prepared by low-temperature dissolution, network reinforcement, washing, and freeze-drying, before being coated with a cross-linked CS/PVA layer using glutaraldehyde, followed by NaOH solidification. SEM revealed a honeycomb-like cellulose framework uniformly covered by the CS/PVA coating, which improved the structural integrity of the skeleton. FT-IR and TG analyses supported the successful construction of the coating and the enhanced thermal stability of CPCG. CPCG displayed a high underwater oil contact angle of 153.8°, which remained above 153° after 30 min, indicating robust underwater oil repellency. Wet CPCG retained 99% of its original height after 30 compression-recovery cycles. Owing to the stable hydration layer, interconnected channels, and improved wet-state resilience, CPCG efficiently separated light and heavy oil/water mixtures and various O/W emulsions. The separation efficiencies for different emulsions were above 99%, and CPCG retained about 93% efficiency after ten cyclohexane/water emulsion separation cycles. This work provides a green and scalable route for constructing biomass-based aerogels for oily wastewater treatment.