Experimental Study on Charge Decay of Electret Filter Due to Organic Solvent Exposure

Abstract

The electret filter is a potential component to remove airborne particles due to its high collection efficiency and low pressure drop. However, its filtration performance is gradually decreased by exposure to organic solvents, which limits the application of electret filters. The effect of ethanol exposure on the filtration performance of polypropylene electret filters was investigated experimentally to clarify the charge decay phenomenon in this study. Experimental results revealed that filter performance is strongly dependent upon the challenged mass and existing state of an ethanol solvent. The filter performance was drastically degraded by exposure to ethanol droplets generated from a solution with ethanol concentrations above 30%; however, it was maintained during exposure to ethanol vapors. This tendency was also seen in the surface potentials of the exposed filter media. In addition, we found that the critical challenging amount of ethanol droplets was in the vicinity of 0.045 g/cm 2 to neutralize a tested electret filter in this study.

Performance of New and Artificially Aged Electret Filters in Indoor Air Cleaners

“…Although electret filters reach a high initial filtration efficiency, it is known that the efficiency can drastically degrade with time due to exposure to particles , , organic solvents , or air humidity . This is usually denoted as aging of the filters and may be related to either compensation or shielding of the fiber charges or to chemical interactions between the aerosol and the filter material .…”

Capture of Ultrafine Particles Using a Film-Type Electret Filter with a Unipolar Charger

“…Therefore, the performance of a filter was affected by the electrostatic force condition on the filter. Previous research showed that ethanol treatment to neutralize a filter significantly decreased the particle collection efficiency (Lee et al, 2002;Choi et al, 2015). The effect of diffusion and field charging did not significantly affect particle collection efficiency for the combination of the unipolar charger and electret filters because the short distance of 25 mm does not improve the collection efficiency.…”

“…The effect of a filter was studied by utilizing a fresh film-type electret filter (FF) and a neutralized film-type electret filter (NF). The NF was prepared by soaking an electret filter in an ethanol solution and drying it at room temperature for 72 hours (Lee et al, 2002;Choi et al, 2015).…”

Air filters for indoor environments: Interlaboratory evaluation of the new international filter testing standard ISO 16890

“…21 Besides that, studies showed that unsaturated vapors of organic solvents do not lead to any discharge of the fibrous material. 21,26 To explain and understand the discharging mechanisms of electret fibers in detail, experimental evidence and further research are needed.…”