Comparative Effects of Inorganic Additives on the Filtration Performance of PVDF-Based Electrospun Air Filters

Electrospun poly(vinylidene fluoride) (PVDF) nanofiber filters are attractive for particulate air filtration because they combine high filtration efficiency with low airflow resistance. Here, three inorganic additives, namely aluminum chloride (AlCl₃), potassium nitrate (KNO₃), and silicon nitride (Si₃N₄), were investigated using formulation-specific electrospinning conditions selected to achieve stable fiber formation. Although all filters exhibited high initial filtration efficiencies above 96%, clear differences were observed in fiber morphology, pressure drop, electrostatic potential decay, and long-term filtration stability. Among the tested samples, the Si₃N₄-containing filter showed the best long-term performance, retaining approximately 94% filtration efficiency after 30 days, whereas neat PVDF decreased to about 85%. These results suggest that differences in long-term filtration stability are closely associated with charge-retention behavior, and that the incorporation of inorganic additives can influence the durability of PVDF-based electrospun nanofiber air filters.