Nanofiber Filter Performance Improvement: Nanofiber Layer Uniformity and Branched Nanofiber

Seong Chan Kim,Qisheng Ou,Chenxing Pei,Handol Lee,David Y.H Pui,Seungkoo Kang,Dong-Bin Kwak

doi:10.4209/aaqr.2019.07.0343

Abstract

ABSTRACT We developed two types of high performance nanofiber filters by increasing the uniformity of the fiber layer’s deposition on the substrate media and by fabricating nanofiber with a branched morphology, in which additional fibers were spun to radiate from the main fibers. We subsequently compared them with conventional and beaded nanofiber filters in terms of particle removal efficiency, filter pressure drop, and particle loading capacity. First, the uniformity of the nanofiber’s deposition, which was visually evaluated using optical and electron microscopes, was increased by removing the substrate surface charge during electrospinning. The uniform nanofiber filters demonstrated a higher filtration efficiency with a lower pressure drop than their conventionally electrospun counterparts, which exhibited irregular fiber layers. Second, branched nanofiber was fabricated by adjusting the viscosity of the polymer solution. The performance of the nanofiber filters was dramatically improved by the decrease in air flow resistance, which resulted from (1) a longer distance streamwise between the fibers and (2) a smaller diameter for the fibers. The enhanced efficiency was also due to (3) the additional fibers branching out from the main fibers.

Highlights

In past decades, it has been well known that particulate matters pose a great threat to human health
We developed two types of high performance nanofiber filters by increasing the uniformity of the fiber layer’s deposition on the substrate media and by fabricating nanofiber with a branched morphology, in which additional fibers were spun to radiate from the main fibers
The performance of the nanofiber filters was dramatically improved by the decrease in air flow resistance, which resulted from (1) a longer distance streamwise between the fibers and (2) a smaller diameter for the fibers

Summary

Introduction

It has been well known that particulate matters pose a great threat to human health. Many efforts have been made to reduce human exposure to particulate matters and minimize its health effects. Among the various efforts to control the air quality, air filtration is the most cost-effective way to remove airborne particles from inlet air flow. As the concerned particle size gets smaller, air filter media needs to be denser and thicker to improve filtration efficiency, which results in increasing filter pressure drop and increasing total operation cost. Beaded nanofiber filters have been proposed to decrease pressure drop because of larger streamwise inter-fiber distance and similar to the regular nanofiber filters performed with high filtration efficiency (Fong et al, 1999; Yun et al, 2010; Wang et al, 2015; Gao et al, 2017)

Methods

Results

Conclusion