Effect of Particle Composition on the Continuous Loading Performance of Medium- and High-Efficiency Electret Media

Abstract

Exposure to particulate matter could cause a wide range of adverse health effects on human beings, which has widely drawn attention. Filtration applications can effectively remove particles and reduce the risk of diseases for humans. Electret media have been often used in residences and commercial buildings due to the permanently charged fibers that contribute to the higher efficiency and lower pressure. However, the efficiency of electret filters would decrease with the increasing loaded dust. To investigate the loading performances of electret media, long-term loading tests were conducted to obtain the time-dependent efficiencies of medium- and high-efficiency electret media that were challenged with polydisperse potassium chloride (KCl) and diethylhexyl sebacate (DEHS) particles, respectively. Results showed that there was no reduction in efficiency of high-efficiency electret media while loaded by KCl. In contrast, the efficiency of high-efficiency electret media increased continually with the increasing loaded KCl mass. However, the efficiency of medium electret media firstly declined and then increased with the accumulation of KCl particles on fibers. The different loading characteristics between medium- and high-efficiency electret media were related to the mechanical structures and charges in fibers. Moreover, efficiencies of medium- and high-efficiency electret media both decreased as a function of deposited particles when electret media were exposed to DEHS. The decline of efficiency was attributed to the factor that the thin liquid film around faces of fibers formed by deposited DEHS particles degraded the electric filed, which was different with the dendrite structures formed by KCl particles.