Study on performance of nanofiber air filter materials

Abstract

Objective Filtration performance of air filtration membrane in high-end application has always been a main concern, attracting much research. The electrospun nanofiber membrane and polytetrafluoroethylene (PTFE) microporous membrane are the widely used membranes as high-end air filtration membrane. In order to further investigate the filtration mechanism of nanofiber air filter materials, to understand the correlations between structure features and their filtration performance, and to provide useful guidance for development and application of high-end air filter materials, these six types of filter composite materials are made from nanofiber structure, which is usually used for high-end air filter materials. Method These six types of filter composite materials were selected. The structure feature is the main factor influencing the filtration performance of air filter materials, and the electrostatic adsorption is also playing an important role in filtration performance. Therefore, the evaluation of air filter materials in structure, electrostatic adsorption and filtration performance were carried out. Results PA6/PET filter composite materials was found to have the highest surface potential which reached to 1.414 kV and its filtration efficiency reached to 99.57%. In contrast, the composite materials with wood pulp paper as substrate showed the lowest surface potential which was 0.070 kV, corresponding to a filtration efficiency of 22.28%, due to the lack of electrostatic adsorption. The crystallinities of samples 1#-6# were 40.7%, 39.4%, 44.2%, 51.7%, 47.6% and 43.5%, respectively. The pressure drops of ePTFE/ES hot-air cotton nonwoven filter composite materials, PTFE/ES hot-rolled nonwoven filter composite materials, and PTFE/ES hot-air cotton nonwoven filter composite materials were 59.7 Pa, 45.6 Pa, 58.8 Pa. The fiber diameter and structure of air filtration membrane also showed to have significant influence on the filtration performance of air filter materials. The smaller fiber diameter, smaller pore size, higher thickness, higher specific surface area resulted in a higher pressure drop and higher filtration efficiency. Conclusion The surface potential played the most important role in filtration performance of filter composite materials, the higher surface potential led to a higher filtration efficiency. Besides, the fiber diameter and pore structure and its distribution also had significant influence on filtration performance of filter composite materials. PTFE mirco-porous membrane was produced by stretching, which had lower pressure drop comparing with the nanofibrous membrane produced from electrospinning.