Application Of Multifunctional Electrospun Nanofibers In Environmental Pollutant Removal

With the advancement of national urbanization and the development of various industries,environmental pollution problems also arise.For example,the atmospheric environment and water environment on which human beings depend for survival.The existence of a large number of environmental pollutants will seriously damage the ecosystem and threaten biological health.However,the environment may contain a lot of water vapor or bacteria,which may affect the removal of pollutants.For example,in the combustion process of particulate matter,the filter membrane is soaked by water/oil and gas,and the adsorbent is attached by bacteria in large number in the adsorption process.Therefore,environmental treatment materials with special functions have become a hot research topic at present.Electrospinning nanofiber is a kind of fiber produced by electrostatic force,which has the advantages of high specific area and abundant porosity.Most importantly,nanofibers can be structurally regulated and chemically modified,making them ideal for environments that contain a lot of water vapor or bacteria.Based on the above content,this paper from the perspective of preparing multifunctional environmental materials,based on electrostatic spinning technology,combined with sol-gel method,surface modification technology,solvothermal method,in situ loading technology and a series of technical methods of chemical modification of organic nanofiber skeleton,so as to two multifunctional composite fibrous membranes are designed.Composite fibrous membrane not only has the ability to remove environmental pollutants,but also can realize self-cleaning or antibacterial applications.In this paper,the function and related mechanism of composite fibrous membrane are studied in detail.The specific contents are as follows:1.A composite fibrous membrane with self-cleaning properties and fine particulate matter（PM）filtering properties was prepared.The composite fibrous membrane uses polyacrylonitrile（PAN）nanofibers as the supporting matrix and surface modification of inorganic silica nanoparticles（Si NPs）and fluorinating agent supported by sol-gel method.Si NPs can not only act as a"bridge"between the fiber and the fluoride agent to enhance the self-cleaning effect,but also make the channel inside the fibrous membrane zigzag,so as to more effectively intercept PM.The surface properties showed that the prepared fibrous membrane had excellent self-cleaning function（the hydrophobic angle was 156°,the oil phobic angle was 144°,and the rolling angle was6°）.The filtration experiment shows that when the thickness of composite fibrous membrane is 0.03 mm,the filtration efficiency of PM₁ can reach more than 99.9%and the pressure drop is 366.4 Pa under the airflow of 2 L/min.Moreover,it still has excellent filtration performance in high humidity environment.The filtration mechanism shows that the trapping of PM₁ by composite fibrous membrane is due to the combined action of physical effect and chemical force.2.The composite fibrous membrane with antibacterial property and adsorption property of 2,4-dichlorophenoxyacetic acid（2,4-D）was prepared.The composite fibrous membrane uses PAN nanofibers as the supporting matrix and loaded with cerium matrix by solvothermal method and in situ loading technique.The Ce-MOF loading can not only improve the adsorption performance of 2,4-D,but also give the composite fibrous membrane good antibacterial activity due to the unique Ce-MOF properties.The adsorption process of 2,4-D by the fiber conforms to the pseudo-second-order kinetic equation in static adsorption experiments,and adsorption isothermal model is more consistent with the Langmuir model.The theoretical adsorption capacity can be calculated as 200.80 mg/g.The removal rate of 2,4-D could reach 90.3%within 6 minutes（the initial concentration is 60 mg/L and the thickness of membrane is 0.12 mm）in dynamic filtration experiment.The adsorption mechanism shows that the removal of 2,4-D is mainly attributed to physical adsorption,hydrogen bond andπ-πinteraction.The antibacterial experiment showed that the antibacterial rate of the composite fibrous membrane itself had 76.65%,and the haloperoxidase activity of Ce-MOF could increase the antibacterial rate of the composite fibrous membrane to 92.91%under the coexistence of Br^-and H₂O₂.