High-Performance Nanoparticle Capture Using Surface Functionalized Electrospun Cellulose Nanofilters

The global spread of COIVD-19, as well as the worsening air pollution throughout the world have brought tremendous attention into the development of materials that can efficiently capture particulate matter (PM). Traditional filters made from fabric, glass fibers, or melt blown fibers exhibit a low efficiency at removing sub-micrometer and nanoscale particles. Additionally, they exhibit limited performance in high humidity, high temperature environments. We suggest that the high porosity of filters composed of nanofibers could provide minimal obstruction to air flow, while their high tortuosity and surface area-to-volume ratio presents an excellent platform for particle capture. In this study, the removal of nanoscale particles via in-house fabricated cellulose nanofilters is significantly enhanced by chemically functionalizing the fibers’ surface via the deposition of the bio-inspired glue polydopamine (PDA) and the polycation poly(diallyldimethylammonium chloride) (PDADMAC). Nanofilters were electrospun from cellulose acetate solutions before being regenerated to cellulose via an alkaline treatment. Cellulose nanofilters were then functionalized using only PDA or the codeposition of PDA with PDADMAC. Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), and high-resolution X-ray photoelectron spectroscopy (XPS) were used to characterize the nanofilters. The effects of filter packing density, fiber layering, and surface functionalization on their performance, i.e., their filtration efficiency, most penetrating particle size (MPPS), performance in a high humidity environment, and filter pressure drop were investigated.