Reusable octenidine-loaded polyetherimide nanofiber filter membranes for efficient air filtration and airborne bacteria inactivation.

To mitigate risks associated with air pollution, mainly particulate matter and airborne pathogens, there is an urgent need for innovative, multifunctional, and reusable air filtration materials. In this study, a reusable nanofiber membrane was fabricated by electrospinning thermally stable polyetherimide (PEI) incorporated with varying amounts of the antimicrobial agent octenidine dihydrochloride (OCT). SEM and elemental mapping confirmed uniform fiber morphology, stable porosity, and homogenous OCT distribution. Among the membranes, 1.5% OCT@PEI demonstrated exceptional filtration performance, achieving 99.971% PM2.5 removal with a low pressure drop (71 Pa) and a reduced packing density (1.026 GSM). Under identical experimental conditions using the same TSI 8130 setup, the membrane outperformed the commercial N95 respirator (97.23%, 83 Pa) and HEPA filter. The high particulate (PM) capture efficiency of this filter was governed by the synergistic effects of mechanical impaction, interception, and electrostatic attraction. Notably, the membrane retained excellent filtration performance after repeated ethanol washings and thermal treatment, demonstrating superior durability and reusability. Antibacterial testing in the air phase revealed strong contact-based antimicrobial activity, achieving 99.5% inactivation of Escherichia coli and 99.1% inactivation of Bacillus subtilis, with consistent performance across repeated use. The intrinsic surface potential of 1.5%OCT@PEI (0.712 kV) significantly contributed to long-range particle attraction; however, storage at elevated temperature (80 °C) induced charge relaxation, confirming thermally activated electrostatic decay. Furthermore, the membrane demonstrated outstanding shelf-life stability, maintaining disinfection efficiency above 99.96% for 112 days, indicating strong chemical compatibility between the OCT and PEI matrix and negligible leaching. This work presents a high-performance, reusable, and multifunctional air filtration material suitable for face masks, air purifiers, and other air-cleaning technologies.