Fabrication And Property Manipulation Of Electrospun Fibrous Materials For PM2.5 Purification

Our living standards and health level are threatened by fine particle pollution(PM2.5).As the core component of an air filter,it is vital to optimize the preparation of filter materials with high efficiency and low resistance.Nanofiber materials prepared by electrospinning have advantageous features of ultrafine mean fiber diameter and good homogeneity.It has tremendous application potential in the filed of air filtration.Mutual influences of electrospinning conditions,fiber membrane structures and filtration performances are studied.Polymer electret properties which affect fiber charging ability and filtration performance are also investigated.The mainly purpose of this paper is optimization the preparation of air filter materials for purification of PM2.5.Firstly,influences of electrospinning conditions on the fiber structures and filtration performances are studied as the example of PA6.It is found that the fiber size and fiber uniformity are mainly controlled by solution concentration and static voltage.Mean fiber diameter is positively correlated with solution concentration.The pore size increases with increasing mean fiber diameter.Thickness and porosity of fiber membrane can be deternmined by electrospinning time.Filtration efficiency and pressure drop increase with decreasing mean fiber diameter and pore size,increasing fiber packing density and thickness.High quality factor can be obtained by manipulating fiber stractures.Secondly,polymer electret properties are found to affect fiber charging ability and filtration performance.Several nanofiber membranes with good electret performance are electrospun using polymer dielectric materials.Their initial surface potentials and surface potential decays are investigated.It is found that initial surface potentials and filtration performances increase with increasing polymer dielectric constants.Polymers with larger dielectric constants provide stronger polymer molecular polarity,and more,polarization charges can be trapped by them.Thirdly,influences of fiber structures on filtration performances are studied by changing elctrospinning conditions.Polarization force,which enhances the interaction of particles and fibers,can be strengthened by decreasing mean fiber diameter and pore size.Charge densities increase with increasing fiber thickness and fiber packing densities.Filtration performance can be high by optimizing fiber membrane structures.Quality factor gets 0.208 Pa-1 when the mean fiber diameter is 250 nm,membrane thickness is 24 ?m and fiber packing density is 0.027 of PVC electret membrane.Finally,effects of mean fiber diameter,fiber packing density,thickness and fiber charges on the filtration efficiency of fiber membranes are investigated using empirical formulas.It is found that the filtration efficiency increases with decreasing mean fiber diameter,increasing fiber packing density,thickness and fiber charges.Increasing fiber charge is a most effectively way to improve filtration efficiency of membrane for particles ranging from 100 nm to 300 nm.