Structure Regulation And Performance Research Of High-efficiency PVA-co-PE Nanofiber Air Filter

With the acceleration of industrialization and urbanization process,lots of particulate matters such as automobile exhaust fumes,factory wastes gases and agriculture dusts are emitted arbitrarily into the air.Many particulate pollutants,whose aerodynamic diameters are less than 2.5?m(PM_2.5)has caused pernicious effects on citizen health and deteriorated climate and sensitive ecosystems.Therefore,improving air quality or designing and developing high-efficiency air filter materials have become a big issue that is closely related to people's health.Commonly,traditional filter material has many drawbacks,such as low filtration efficiency,low service life and high energy consumption.Compared with the microfiber film filter,the nanofibers are now widely considered as the popular filterable raw material in the field of air filtration due to their large specific surface area,high porosity,tortuous pore structure and high filtration accuracy.However,optimizing the structure of the nanofiber filter cloth by adjusting the preparation process and continuously improving the comprehensive filtering performance still requires more in-depth systematic research.In view of the above technical issures,regulating the structure of PVA-co-PE nanofiber layer or composite filter to improve the filtration performance,designing a high efficiency and low resistance,high stability,high yield of air filter material.To provide theoretical and technical support for the application of PVA-co-PE nanofibers in the field of air purification.The details are summarized briefly as follows:Firstly,PVA-co-PE,CAB,electrect?SiO₂?and permanent magnet(SrFe₁₂O₁₉)were prepared different concentrations of SiO₂/PVA-co-PE and SrFe₁₂O₁₉/PVA-co-PE nanofibrous composite membrane during melt-phase separation process.The influence of morphology,gas permeability,electrostatic and magnetic saturation on the filtration performance of the modified composite nanofiber membrane were also analyzed.Nanofiber membranes have electrostatic charge and permanent magnetic properties respectively.Most particles in the air will carry a certain positive or negative charge,when the charged particles meet the electret or magnetic fiber,the particles are adsorbed on the surface of the fiber due to charge attraction or the Lorentz force in the electromagnetic field.When the concent of SiO₂ added to 13%,the filtration efficiencfy of SiO₂/PVA-co-PE fibrous membrane is 97.127%?incredsed by 10.454%?and the pressure drop reduce by 46 Pa.When the concent of SrFe₁₂O₁₉added to 13%,its filtration efficiency reach 94.945%?incredsed by 13.01%?and the resistance drop reduce by 33 Pa.In this work,a mixed solution of tert-butyl alcohol?TBA?and water was employed to stably disperse PVA-co-PE nanofibers,nanofibrous filter media with various controllable three-dimensional structure were then prepared via three nanofiber-suspension drying techniques of spray-air drying,spray-freeze drying and container loading-freeze drying.In the end,the relationship between the structureof PVA-co-PE the nanofiber with controllable three-dimensional structure and filtration mechanism performance and stability was systematically.The theoretical analysis shows the stable three dimensional structure of nanofiber network which can provide superior torturous channels for capturing airborne nanoparticles and facilitating the penetration of air flow indicating a typical deep bed filtration.Nanofiber layer porosity increases from 76.6%to 97.3%,various pore size from 0.493 to 2.268?m as well as a increased nanofiber layer thickness from about 10 to 55.3?m for filter media with 2.667 g/m² nanofiber coverage density?NFCD?,the filter media possess a best comprehensive filtration performance with the quality factor=1.110 mmH₂O^-1?99.955%and 6.73 mmH₂O?.Meanwhile,a best efficient performance with efficiency=99.999%?0.645 mmH₂O^-11 and 17.86 mmH₂O?at NFCD=6.583 g/m².The PVA-co-PE nanofibers were penetrated through a PP needle-punched matrix substrate by a freeze-drying method to prepare a composite aerogel filtration material having a three-dimensional network structure with stable fiber staggered points.The result shows that the filter possess a optimal filtration performance when the mass ratio of alcohol to water is 1.5:1,the concentration of nanofiber is 0.9%and the gram weight was 9.34 g/m²,the filtration efficiency was 99.936%,and the pressure drop was only 80 Pa.In addition,comparing the filtration performance of commercial PP filters and three-dimensional framework-enhanced PVA-co-PE nanofiber filters after high-humidity,high-temperature,and low-temperature processing,the studies have shown that the formel filtration efficiency sharply decline indicates that the filter life is poor.But the filtration efficiency of the nanofibrous filter is almost unchanged,showing excellent filtration stability.