Linking structure and filtration performance in electrospun polyethersulfone filters: The role of deposition uniformity and configuration

This study investigated the morphological and structural characteristics of electrospun polyethersulfone (PESU) nanofiber filters, with a particular focus on deposition non-uniformity, an often overlooked yet critical factor in practical filtration performance. Single-layer filters with fiber diameters of 67, 122, 305, and 636 nm were fabricated and evaluated under equivalent pressure drop conditions. Filtration efficiency was found to be inversely correlated with fiber diameter, with 67-nm fibers demonstrating the highest quality factor (QF), illustrating the trade-off between filtration efficiency and airflow resistance. Electrospinning onto coarse nonwoven substrates initially led to non-uniform fiber deposition due to electric field distortion, which gradually diminished with continued deposition. To evaluate structural effects, three filter configurations—single-layer, layer-stacking, and uniform—were compared. A substrate-independent, uniformly deposited filter showed the best performance (QF = 0.051 Pa⁻¹), representing a 60% and 21% improvement over single-layer and stacked filters, respectively, while using only 0.18 g m⁻² of polymer. Complementary three-dimensional simulations revealed how fiber morphology and deposition uniformity influence particle transport and pressure drop. The findings provide practical guidance for the design of nanofiber-based air filters tailored for building ventilation systems, supporting energy-efficient indoor air quality improvement in HVAC applications.