Peroxidase-Catalyzed Fabrication of a Mechanically Robust Nanofibrillated Cellulose-Based Aerogel with Antibacterial Activity for Efficient Oil–Water Separation

The porous aerogels based on nanofibrinogen cellulose (NFC) have the characteristics of superhydrophilicity and underwater oleophobicity, which have potential application values in the treatment of oily wastewater. However, many methods for fabricating NFC-based aerogels suffer from high energy consumption, toxicity, and secondary pollution. Therefore, it is urgent to develop a green and efficient preparation method. Herein, an enzymatic technique is presented for developing superhydrophilic and antibacterial NFC-based aerogels for efficient oil–water separation. Notably, multiple cross-links were built among the vinylated NFC (VNFC) and phenolic hydroxyl-modified polyethylenimine (mPEI) molecules under the catalysis of horseradish peroxidase (HRP), including VNFC-g-mPEI, self-cross-linking of VNFC, and mPEI. The prepared VNFC-g-mPEI aerogel exhibits superior mechanical property, elasticity, and structural stability in both wet and dry states. In addition, the obtained superhydrophilic and underwater oleophobic properties endow the NFC-based aerogel with an outstanding oil–water separation performance. Even after 50 cycles of oil–water separation under harsh conditions, the separation efficiency and flux remain above 99% and 5000 L m–2 h–1, respectively, companying with encouraging antibacterial properties against E. coli and S. aureus, thus effectively extending the service life of the aerogels. This work provides an insight into the eco-friendly development of NFC-based aerogels and expands their application prospects in the oil–water separation field.