Ecofriendly and antibacterial poly(lactic acid) nanofibrous membranes forhigh-efficiency and low-resistance filtration of airborne particulate matters

Fine particulate matters (PMs) generated during industrial production pose a serious threat to human health and are one of the main hazards causing occupational diseases at work. The contemporary traditional masks have poor filtration effect, high breathing resistance, low dust holding capacity, not easy to degrade as well as insignificant antibacterial effect, for this reason, a high-efficiency and low-resistance poly(lactic acid) (PLA) antibacterial biodegradable nanofibrous filtration membrane has been developed. Structurally ordered nanohybrid structure CNT@ZIF-8 with large specific surface area were successfully synthesized by inducing the growth of zeolitic imidazolium ester framework-8 (ZIF-8) on carbon nanotubes (CNT) by microwave-assisted synthesis method. Based on the electrospinning-electrospray technology, CNT@ZIF-8 was successfully embedded onto PLA fiber, and PLA composite fibrous membranes (CNT@ZIF/PLA) with different fiber diameters were prepared by regulating the mass fraction of CNT@ZIF-8. The filtration performance and air resistance of CNT@ZIF/PLA nanofibrous membranes at different flow rates were investigated, and the effects of different mass ratio of CNT@ZIF-8 on the mechanical properties and antibacterial properties were investigated. The results show that the tensile strength of CNT@ZIF/PLA nanofibrous membrane increases up to 47% (18.5 MPa) and the fracture toughness increases 100% (2.9 MJ/m³) compared with that of pure PLA membrane. As the mass fraction of CNT@ZIF-8 increases, the air resistance gradually decreases, and at the test flow rate of 32 L/min, the air resistance of 12%CNT@ZIF/PLA nanofibrous membrane is only 82.6 Pa, which is 45.1% less than that of Pure PLA fiber membrane, and after the 180 min long filtration test, there is no significant change observed in the filtration efficiency of PMs. At the test flow rate of 85 L/min, the filtration efficiency of CNT@ZIF/PLA nanofibrous membrane for PM_0.3 is more than 89%, and after 5 min of irradiation by the sunlight simulator, the antibacterial efficiency against both E. coli and S. aureus reach 100%.