Ultralight, elastic, magnetic and superhydrophobic cellulose nanofibril based aerogel with layer-support structure designed for both excellent oil-water separation and efficient PM2.5 removal

It is unquestionably a great challenge to develop elastic cellulose nanofibril (CNF) based aerogels satisfying both excellent oil-water separation and efficient PM2.5 removal. In this work, the CNF based aerogel with a layer-support structure was design through CNF as the aerogel scaffold and compositing with bamboo activated charcoal (BAC) and Fe3O4 as the functional particles, followed by hydrophobic modification. The resultant aerogel displays ultra-low density (30.12 mg/cm3), good specific surface area (25.38 m2/g), magnetism (9.44 emu/g) and superhydrophobicity (water contact angle (WCA) of 153.8° and slide angle (SA) of 7°). Benefiting from high internal porosity of the layer-support structure, the system shows excellent absorption efficiency (16.79–51.93 g/g) for various oils and filtration efficiency (97.85 ± 1.2%) for PM2.5 with a low pressure drop (58 Pa). As well as it also shows outstanding mechanical properties and able to maintain a high recovery of 75.4% at 50% strain (corresponding 25.29 kPa) due to the flexibility of the “support” structure given by methyltrimethoxysilane (MTMS). Based on its simple preparation and excellent properties, the magnetic and superhydrophobic CNF/Fe3O4@BAC composite aerogel shows great potential in multifaceted separation technique and recycling of natural resources.