Fluorine-free construction of robust antibacterial cellulose nanofibril aerogels via a fully aqueous strategy for simultaneous PM2.5 capture and oil absorption

Efficient removal of fine particulate matter (PM2.5) from air and organic pollutants from water remains a critical challenge in the treatment of industrial emissions. Cellulose nanofibril (CNF)-based aerogels are promising media, but conventional hydrophobic modification often relies on fluorosilanes or organic solvents. Here, we developed a reusable, antibacterial CNF-based aerogel through a fully aqueous dual-silane modification strategy incorporating bamboo-activated carbon (BAC)@Ag composite particles. In this system, protonation of the amino groups of 3-(2-aminoethylamino)propyltrimethoxysilane in water generated cationic species that promoted the uniform dispersion and aqueous hydrolysis of octyltrimethoxysilane. The hydrolysed silane chains formed covalent bonds with the hydroxyl groups of CNFs, imparting hydrophobicity (water contact angle of 135.4°), thermal stability, and mechanical resilience (height loss of only 18.8% after 50 compression cycles at 50% strain) to the aerogel, supporting its reusability. BAC provided a porous, negatively charged platform for pollutant capture and supported uniformly dispersed Ag nanoparticles, which produced a bacterial reduction of 99.99% against both Escherichia coli and Staphylococcus aureus . The resulting aerogel achieved a PM2.5 filtration efficiency of 98.62% at a low pressure drop of 37   Pa and absorption capacity of 28.2-55.0   g/g for oils and organic solvents. Multiphysics simulations were performed to examine PM2.5 capture, oil–water separation, and antibacterial kinetics. This work provides an aqueous, fluorine-free strategy for developing multifunctional aerogels.