Fabrication And Investigation Of Nanofiber-Based PM_2.5 Purification Materials

In recent years,alarming levels of particulate matter?PM?in air pose a serious health threat to the public.Particulate matter?PM?is a complex mixture of particles and liquid droplets,and its main components include organic carbon,elemental carbon and other organic matter,nitrate,sulfate,and inorganic substances,such as silica.Based on the particle size,PM is categorized as PM_2.5.5 and PM₁₀,which refer to particles with aerodynamic diameters below 2.5 and 10?m,respectively.PM_2.5.5 pollution is particularly harmful since it can penetrate human bronchi and lungs owing to the small particle size.Numerous epidemiological studies have demonstrated that long-term exposure to PM_2.5.5 pollution can result in various respiratory and cardiovascular diseases.A recent report by the U.S.Environmental Protection Agency indicates that 2.1 million deaths occur worldwide each year because of PM_2.5.5 pollution.Therefore,a method to effectively remove PM_2.5.5 from the air is urgently needed.Nanofibers have larger surface areas,variable diameter,and light weight than micrometer-sized fibers,which can dramatically improve their interactions with PM and enhance their efficiencies.In this paper,nanofibers were prepared by electrospinning and used for PM pollution filtration.The main contents are as follows:?1?Poly?m-phenylene isophthalamide??PMIA?nanofibers were selected as a skeleton material because of their excellent heat resistance,corrosion resistance,and mechanical strength.Morphology,diameter distribution,mechanical properties of the PMIA was regulated by tuning the solution properties and the electrospinning process.As a result,when the content of solvent LiCl/DMAc achieved 4 wt%,the PMIA nanofibers exhibit a smooth surface and uniform size.?2?Based on the first part of the research,a facile strategy was suggested for constructing hierarchical structured PMIA/PMSQ-NFs fibrous membranes was obtained.PMIA nanofibers were selected as a material with a coarse texture to construct a skeletal support,ultra-fine PMSQ nanofilaments were grown in-situ on electrospun PMIA nanofibers,forming a fine texture.Model PM particles were generated from cigarette smoke by burning,the surface chemical properties of PM particles were conducted using XPS,IR.Such a free-standing binary hierarchical structured network was applied to air filtration,compared with the pristine PMIA nanofibers,we found that the PM_2.5.5 and PM₁₀0 capture capacities were significantly enhanced.?3?The removal performance of the polar spider-web-like nanofiber membrane was thoroughly investigated by controlling the surface chemistry and micro-structure of the air filters,and the adsorption properties of the composite membrane were tested in the field.Chitosan and polyvinylpyrrolidone with high polarity were selected as raw materials to fabricated CS/PVP spider-web-like structured polar nanofibers via a facile sequential electrospinning.The especial structure and surface chemical properties of CS/PVP nanofibers play a synergistic role in capturing PM pollution.The successful fabrication of such material may provide a new idea for the design and development of new purification materials for various applications.