MOF-based nanofiber filters via a scalable synthetic strategy serve a dual role in removing both PM _2.5 and formaldehyde effectively.

Particulate matter (PM) air pollution is associated with various adverse health effects. Heavy outdoor air pollution, especially smog, has significantly impacted the living quality of residential environments. Here, we report the fabrication of silk fibroin/polyvinyl alcohol (SF/PVA) nanofiber air filters for the filtration of PM pollution using the electrospinning technique. Silk fibroin is a type of protein fibers which is widely available with excellent environmental sustainability, and PVA is commonly used for continuous nanofiber fabrication. Our results showed that, the PM$_{2.5}$ removal efficiency of the SF/PVA filter was 99.11$\times$0.24%, which was about 10% higher than that of the pure PVA filter under the same pressure drop of 50 Pa. In a 24-hour filtration test, the filtration efficiency of this composite SF/PVA filter remained at a high value of 98.97% after 24 hours. The results indicate that the superior filtration performance of the SF/PVA nanofiber air filer, which holds a great promise in PM pollution prevention.

Aerosol particles, such as the widespread COVID-19 recently, have posed a great threat to humans. Combat experience has proven that masks can protect against viruses; however, the epidemic in recent years has caused serious environmental pollution from plastic medical supplies, especially masks. Degradable filters are promising candidates to alleviate this problem. Degradable nanofiber filters, which are developed by the electrospinning technique, can achieve superior filtration performance. This review focuses on the basic introduction to air filtration, the general aspects of face masks, and nanofibers. Furthermore, the progress of the state of art degradable electrospun nanofiber filters have been summarized, such as silk fibroin (SF), polylactic acid (PLA), chitosan, cellulose, and zein. Finally, the challenges and future development are highlighted.