Production of Ultrafine PVDF Nanofiber-/Nanonet-Based Air Filters via the Electroblowing Technique by Employing PEG as a Pore-Forming Agent

Abstract

Particles with diameters smaller than 2.5 μm (PM2.5) can penetrate the respiratory system and have negative impacts on human health. Filter media with a porous surface and nanofiber/nanonet structure demonstrate superior filtration performance compared to traditional nano- and microfiber-based filters. In this study, nanostructured filters were produced using the electroblowing method from solutions containing different ratios of poly­(vinylidene fluoride) (PVDF) and polyethylene glycol (PEG) polymers for the first time. By increasing the water-soluble PEG ratio in PVDF/PEG blend nanofibers and employing a water bath treatment to the produced mat afterward, a more porous fibrous structure was obtained with a lower average fiber diameter. Notably, the removal of PEG from the PVDF/PEG (3–7) sample, which had the highest PEG content, exhibited clustered nanofiber-/nanonet-like structures with average diameters of 170 and 50 nm at the points where the fibers intersect. Although this process resulted in a slight decrease in the filtration efficiency (−1.3%), the significant reduction observed in pressure drop led to a 3.2% increase in the quality factor (QF). Additionally, by exploiting the polarizability of PVDF under an electric field, the filtration efficiency of the nanostructured PVDF filters enhanced with a ratio of 3.6% after corona discharge treatment leading to a 60% improvement in the QF. As a result, the PVDF/PEG (3–7) sample presented an impressive filtration efficiency of 99.57%, a pressure drop (ΔP) of 158 Pa, and a QF of 0.0345 Pa–1.

Katmanlı ve bimodal nanolifli yapılarla filtrasyon performansının artırılması

“…A bimodal approach is being studied to obtain low pressure drop values by increasing the filtration efficiency of filter mats. The nanofibers mixed between the microfibers on the surfaces formed by combining micro and nanofibers with bimodal filter mats increase the filtration efficiency by creating new air channels and prevent the pressure drop from increasing [12,13]. In the study conducted by Lin et al, it was revealed that a bimodal filter showed a high filtration performance (98.43%) when the average fiber diameters were 2.44 and 0.13 μm,…”

Polyvinylidene Fluoride-co-hexafluoropropyle Electrospun Nanofiber Membranes for PM0.3 Filtration

“…Therefore, air filtration materials play a fundamental role in protecting individuals by effectively filtering out harmful airborne particles. Currently, fiber air filtration materials are extensively used primarily due to their high permeability and large specific surface area. − The main filtration mechanisms of air filtration materials include diffusion, inertia, interception, gravity, electrostatic adsorption, and other filtration mechanisms. − The most widely used fiber air filtration material is the melt-blown and spunbond nonwoven, which is enhanced with higher electrostatic forces under the application of the electret process to improve its air filtration efficiency via the electrostatic adsorption mechanism. , However, rapid attenuation of electrostatic forces and limited stability of filtration efficiency are inevitable. − These drawbacks not only limit further improvements in filtration efficiency but also induce higher air resistance.…”