Large polystyrene microsphere embedded 3D polycaprolactam-6 nanofiber mats with high filtration performance for ultrafine particulates

Nanofiber filters often face the challenge of achieving both high filtration efficiency and low pressure drop simultaneously. To address this issue and strike a balance between these two critical parameters, a novel three-dimensional (3D) nanofiber filter with high porosity, integrated with large microspheres, was developed. A microsphere suspension was prepared for one-step spinning, utilizing polycaprolactam-6 (PA-6) and polystyrene (PS) microspheres with large particle sizes to design an innovative PS microsphere/PA-6 nanofiber membrane structure. This membrane was specifically engineered for the filtration of ultrafine particulate matter (PM) with diameters ≤ 1 μm. Through gas jet spinning, PS microspheres were successfully embedded into PA-6 nanofibers, resulting in a “bead chain”-shaped PS microsphere/PA-6 nanofiber membrane with a fluffy, three-dimensional structure. By adjusting the ratio of PS microspheres, the stacking configuration of the nanofiber membrane was optimized. The optimal filtration performance was achieved when the microspheres were incorporated at 1.5 % w/w. Under these conditions, the membrane demonstrated exceptional filtration efficiency of 99.58 ± 0.09 % at a high flow rate, while maintaining a low pressure drop of 105 ± 2 Pa. This combination of high-efficiency filtration and low resistance highlights the superior performance of membrane, making it a promising solution for advanced filtration applications.