Preparation And Properties Of Keratin-based Nonwoven Filters

With the rapid advancement of world industrialization,the problem of air pollution cannot be underestimated.Some printing house,power stations,paper mill,etc.often produce large amount of dusty exhaust gas.After being discharged into the air,it is easy to produce new pollutants through photosynthesis,which will bring great threats to individual health.Using fiber-based air material to remove air pollutants is one of the most effective ways to alleviate and even solve the above problems.There are still some deficiencies in the practical application of commercial fiber air filter materials.For example,secondary pollution caused by refractory raw materials and it is also difficult to remove both particle matter and harmful gases at the same time.Keratin is not only widely sourced and biodegradable,but also contains functional groups that can remove HCHO.However,most of keratin are not effectively utilized or even discarded,resulting in a waste of resources.Freeze drying technology is a common method for preparing porous materials,which can retain the essential structure and morphology of fiber-based filter materials.If the protein rich in functional groups is combined with freeze-drying technology,it is expected to prepare functional fiber air filter materials that can filter PM and remove HCHO at the same time.Therefore,this project selects keratin extracted from waste duck feather as raw material and porous nonwoven material prepared by bicomponent microfiber(BMF)as substrate.The application potential of keratin in the field of air filtration was explored by freeze-drying technology.The specific research contents include the following aspects:Firstly,Structure and properties of fiber-based nonwovens prepared by different reinforcement processes:Nonwovens with three-dimensional structure were prepared by needling-punched or air bonding reinforcement technology.Through the characterization and analysis of the apparent morphology,mechanical properties and pore diameter of the substrate,the best reinforcement process is determined.The test results show that the best process is to strengthen the fluffy web with needling-punched reinforcement first and then with air bonding reinforcement.The substrate has excellent three-dimensional structure with an average pore diameter of 33.030?m.Then,Influencing factors and mechanism of preparation of keratin nanofibers(KNF)by freeze-drying technology were studied:The results show that freezing temperature and keratin solution concentration affect the morphology,size and distribution of KNF,which change the apparent structure and pore size morphology of keratin based air filter materials,and then affect the air filtration performance of KNF/BMF nonwovens.When the freezing temperature was?198?and the concentration of keratin solution was 0.6?0.8 wt%,the KNF was evenly filled in the pores of the substrate,and the diameter of nanofibers was uniform.Finally,Structure control and performance analysis of KNF/BMF nonwovens material:The composition and structure of KNF and BMF were regulated by changing the freezing device before freeze-drying.Then,for the thermal reinforcement of KNF/BMF nonwoven materials,the interface bonding mode of KNF and BMF is analyzed,and the efficiency and mechanism of KNF/BMF nonwovens in removing PM and HCHO are explored.The results show that when the concentration of keratin solution is 0.7 wt%,the quality factor(QF)of KNF/BMF nonwoven materials is the highest,which is 0.03 Pa^-1.Finally,the optimal freezing temperature for the preparation of filter material is?198?and the concentration of keratin solution is 0.7 wt%.