Green Synthesis of Silver Nanoparticles from Solidago microglossa in Cellulose Acetate Nanofibers for Antibacterial Air Filtration

Silver nanoparticles (AgNPs) have emerged as promising materials for biocidal applications; however, conventional synthesis routes often rely on hazardous chemicals, requiring post-synthesis purification and raising environmental and health concerns. Here, AgNPs were rapidly produced (<20 min) by green synthesis using Arnica-brasileira (Solidago microglossa) extract and incorporated into electrospun cellulose acetate (CA) nanofibers. The resulting AgNPs were spherical and colloidally stable (ζ = −28.6 mV; 31 nm), as confirmed by EDS, XRD, and XRF. SEM and TEM showed that AgNP incorporation altered nanofiber morphology, reducing the average fiber diameter from 420 nm (neat CA) to <260 nm, while FTIR, DSC, and TGA indicated changes in the structural and thermal behavior of the CA matrix. The air-filtration performance was evaluated under nanoparticle aerosol conditions and benchmarked against two commercial reference filter media. AgNP-loaded mats achieved a >99.48% collection efficiency with pressure drops below 260 Pa. Overall, this work demonstrates a fast, low-cost, and sustainable route to AgNP-functionalized CA nanofibers with high-efficiency nanoparticle filtration and added antimicrobial potential.