Slip-Effect Functional Air Filter for Efficient Purification of PM2.5

Abstract

Fabrication of air filtration materials (AFM) that allow air to easily flow through while retaining particles is a significant and urgent need due to the harmful airborne particulate matter pollution; however, this is still a challenging research area. Herein, we report novel slip-effect functional nanofibrous membranes with decreased air resistance (reduction rate of 40%) due to the slip flow of air molecules on the periphery of nanofibers. This was achieved through careful control over the diameters of electrospun polyacrylonitrile fibers and aperture size of fiber assembly. Fiber assembly with 86% of fiber diameters between 60–100 nm was found to be most effective for slip flow, as these diameters are close to the mean free path of air molecules (65.3 nm). Significantly, an equilibrium factor τ = df/d2 has been introduced to elucidate the effect of distance of adjacent fibers on the drag force of airflow. Furthermore, the most effective aperture size (>3.5 μm) for slip-effect has been determined. Ultimately, the new material displayed low air resistance of 29.5 Pa, high purification efficiency of 99.09%, good transmittance of 77%, and long service life. The successful fabrication of such materials can facilitate the development of high-performance AFMs for various applications.

Electrospun Polyacrylonitrile Nanofibrous Membranes for Point‐of‐Use Water and Air Cleaning

“…Zhao et al . prepared PAN nanofibers in various fiber diameters using lithium chloride salt (LiCl) at various concentrations.…”

Design of three‐dimensional gradient nonwoven composites with robust dust holding capacity for air filtration

“…Ding and coworkers have successfully created the nanofiber/nets membrane, which maintains a low air resistance when filtrating the ultrafine particles . They explained the low resistance by the nanonets would exhibit great “slip effect” due to the slip flow of air molecules on the periphery of nanofibers, which greatly decreased the air resistance . Souzandeh et al .…”

A High Electrical Field Effect to Ultrafine Particle Filter Performance on Motor Vehicle Exhaust

“…Generally, particulate matters originate from different sources as the primary and secondary emission. According to the size distribution of particulate matter can be classified into PM 0.1 , PM 1.0 , PM 2.5 , and PM 10 which are the particulate matter with the diameter less than 0.1 µm or is called as ultrafine particles [1], 1.0 µm, 2.5 µm, and 10 µm respectively [2,3].…”

“…As a consequent, there are many guidelines established to limit the average daily or yearly exposure to particulate matter. Another effort is by conducting a reduction, capture, filtration, or removal methods of particulate matter, such as porosity-based particulate filter [8], nanofibrous membranes [3], and many others. The previous study has been conducted to focus on the additive for fuel to decrease particulate matter emission chemically, using glycerol triacetate [9].…”