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 Fe 3 O 4 as the functional particles, followed by hydrophobic modification. The resultant aerogel displays ultra-low density (30.12 mg/cm 3 ), good specific surface area (25.38 m 2 /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/Fe 3 O 4 @BAC composite aerogel shows great potential in multifaceted separation technique and recycling of natural resources.