A reusable nanofibrous air filter with anti-wetting microbead coating

Filtration technologies for fine dust particles have garnered attention as public awareness of air pollution has increased. In this study, we report a microbead-coated polyacrylonitrile nanofibrous membranes (MB-NFMs) filter, which is a reusable PAN nanofiber-based air filter with high dust-filtration efficiency. The MB-NFMs filter comprises a dual-layer structure composed of hydrophilic PAN nanofibers coated with hydrophobic microbeads to produce high filtration efficiency and water droplet cleaning ability. This membrane has water contact angles of approximately 144 degrees, which allows water droplets to roll off its surface and carry captured dust particles with them. Furthermore, we discovered that the MB-NFMs filter has sufficient wetting resistance to maintain its hydrophobicity under raindrop impacts. The MB-NFMs filter had a removal efficiency of over 99.8% for PM2.5. Repetitive dust-filtration and water droplet-cleaning cycles were performed to evaluate the MB-NFMs filter's ability to clean water droplets. The filtration efficiency was higher than 99.8% throughout the tests, and the pressure drop was recovered by 99% after each cleaning cycle. The fabricated MB-NFMs filter is a viable solution for highly efficient and reusable dust-particle filtration. The MB-NFMs filter does not require periodic mainte-nance due to its water droplet cleaning ability, providing an economic advantage over conventional air filters.