Fabrication of Covalent Organic Framework-Loaded Nanofibrous Membranes via Needle-Based Electrospinning for Efficient Removal of Particulate Matter

Submicron NaCl aerosol particles, characterized by their high penetrating ability and associated environmental health risks, present a significant challenge to conventional filtration materials. Traditional nanofiber membranes, which primarily rely on physical interception, often struggle to simultaneously achieve high filtration efficiency and low airflow resistance. To address this, we propose a strategy for the in situ loading of the TpPa-1 covalent organic framework (COF) onto PVA, PAN, and PCL nanofiber membranes via needle-based electrospinning. The resulting TpPa-1@PVA, TpPa-1@PAN, and TpPa-1@PCL composite membranes were fabricated and systematically evaluated for their filtration performance against 0.3 μm NaCl aerosols. Notably, the TpPa-1@PCL composite membrane achieved a removal efficiency of 99.89%, alongside a 28.05% reduction in pressure drop, yielding a quality factor of 0.1157 Pa–1. To elucidate the capture mechanism at the molecular scale, we performed CP-BSSE-corrected DFT calculations using the upgraded def2-TZVP basis set. The results indicate that the C═O group in the β-ketoeneamine structure forms a strong noncovalent interaction with Na+ via ion–dipole interactions (Eads = −87.49 kJ/mol; verified to be −84.56 kJ/mol by ωB97X-D calculations). This interaction exceeds the threshold for physical adsorption but still falls within the category of strong noncovalent ion–dipole interactions. Furthermore, NBO natural population analysis provides quantitative evidence of charge transfer (ΔqNa = −0.062 e, E(2) = 78.5 kJ/mol), indicating that such transfer is largely independent of specific functional groups. Collectively, our multiscale analyses demonstrate that the TpPa-1 composite fiber membrane effectively reduces pressure drop while maintaining superior filtration efficiency, offering rational design guidance for the development of next-generation high-performance, low-resistance air filtration materials.