Dual-mode sunlight/darkness driven composite filtration: Highly efficient self-cleaning based on pre-treated PP/Ag@T-ZIF-8 meltblown nonwoven fabrics

To address the issue of secondary contamination caused by the lack of antibacterial properties in polypropylene (PP) meltblown nonwoven fabrics while preserving its core filtration performance, this work employed an immersion-ultrasonic method to construct Ag@T-ZIF-8 antibacterial materials with a core-shell structure. Subsequently, PP/Ag@T-ZIF-8-G composite meltblown fibers was prepared via covalent modification and meltblown spinning technology. The systematic characterization of Ag@T-ZIF-8 was conducted in terms of its chemical structure, microstructure, and photocatalytic antibacterial performance. The effects of Ag@T-ZIF-8 on the antibacterial, filtration and comfort properties of the composite melt-blown nonwoven fabrics were investigated, and the enhancement mechanisms of antibacterial and filtration were revealed. The results indicate that Ag@T-ZIF-8 exhibits a uniform core-shell structure with a particle size of 40∼50 nm and a specific surface area of 531.83 m²/g. At an antibacterial concentration of 200 mg/L, it achieves a 99.99% antibacterial rate against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) within 8 min in the dark or 4 min under illumination. Compared with PP meltblown nonwoven fabrics, it demonstrates 73.31% in filtration efficiency for particles with a pressure drop of only 37.3 Pa. When Ag@T-ZIF-8 loading reaches 1 wt%, the composite meltblown fabrics completely eliminates E. coli and S. aureus after 160 min of illumination or 240 min in the dark. This outstanding comprehensive filtration performance stems from a synergistic filtration mechanism combining mechanical filtration, ionic adsorption, and dual-mode antibacterial action under light or dark condition. Integrating superior filtration capabilities, broad-spectrum antibacterial properties, and wear comfort, PP/Ag@T-ZIF-8-G meltblown nonwoven fabrics deliver a highly efficient integrated antibacterial-filtration solution for the medical protective field.