Construction of highly efficient flame retardant cellulose nanofibrils/bamboo activated charcoal based composite aerogel sheet for excellent PM2.5 removal

Developing biomass air filter materials with efficient filtration for particulate matter 2.5 (PM2.5) and low pressure drop is a great challenge. Targeting this issue, cellulose nanofibrils (CNF) were employed as the skeleton materials mixing with bamboo activated charcoal (BAC), polyethyleneimine (PEI), and ammonium polyphosphate (APP) as the functional fillers, followed by freeze-drying and hydrophobic modification to prepare CNF/BAC based composite aerogel sheet for capture for PM2.5. The resulting aerogel sheet showed good filtration efficiency for PM2.5 (98.64 %), which benefited from the three-dimensional network structure from CNFs and PEI and electrostatic adsorption of both BAC and APP with negative charge. After reusing for 5 times, the filtration efficiency of the system could still maintain at 95.88 %. In addition, the introduced both APP and PEI made the system have excellent flame retardant through the synergistic effect of nitrogen and phosphorus. In view of excellent properties and simple preparation, this work supplies a promising way to prepare multifunctional biomass air filter.