Cellulose nanofibril/PVA/bamboo activated charcoal aerogel sheet with excellent capture for PM2.5 and thermal stability.

It is still a challenge to prepare air filtration materials with high filtration efficiency and good thermal stability from renewable materials. In this study, cellulose nanofibril (CNF), poly (vinyl alcohol) (PVA), and bamboo activated charcoal (BAC) were used to build an air filtration system with double filtration by mixing and freeze-drying. The resulting CNF/PVA/BAC aerogel sheet reached a filtration efficiency of 99.69% for PM2.5 due to its double filtration from the network structure of CNF and electrostatic adsorption of BAC. The composite material also showed high thermal stability with its filtration efficiency over 95% even after exposure to 200 °C. After modification, the hydrophobic CNF/PVA/BAC filtration sheet could be reused for over 5 times by water washing whereby the filtration efficiency remained above 95%. The environmentally friendliness excellent filtration efficiency and simplistic fabrication make the aerogel sheet a potential material choice to cope with the severe air pollution today.