Preparation Of Nylon 6 Multi-level Antibacterial Nanofiber Membrane And Study Of Its Air Filtration Performanc

Smog pollution caused by particulate matter has caused serious environmental and health problems.Due to the complex structure,diverse sources and complex evolution mechanism of particulate matter,it is still a great challenge to control particulate pollution,and air filtration materials have gradually become a research hotspot.In particular,the outbreak and epidemic of COVID-19 in 2019 makes it urgent to research air filtration technology with antibacterial function and good filtration performance.However,most air filters cannot balance high filtration efficiency with low pressure drop.Electrospun nanofibers have large specific surface area,adjustable porous structure and simple preparation process,so they are excellent candidate materials for filtration.Therefore,the application of electrospinning nanofibers in air filtration is attracting more and more attention.In this paper,PA6 Multistage Structure Nanofiber Files（PA6 Multistage Structure）with branched fibers were prepared by adjusting the spinning process by adding organic branched salt tetrabutylammonium hexafluorophosphate（TBAHP）into electrospun nylon 6（PA6）.PA6 MSNFs),the formation of branching fiber and its influence on filtration performance were studied from pore size distribution and bulk density.Furthermore,silver nitrate（Ag NO₃）was further added to modify the pa6&Ag multistage structure nanofiber membrane（PA6&Ag MSNFs）with antibacterial properties was prepared.The effects of Ag NO₃ concentration and non-woven weight on the filtration performance were studied.Combined with the electrostatic adsorption of polystyrene（PS）fiber and polyvinylidene fluoride（PVDF）fiber and the fluffy structure,a kind of composite air filter material with gradient pore structure and high efficiency,low resistance and antibacterial performance was constructed.（1）PA6 MSNFs with good mechanical properties,small pore size and excellent filtration efficiency were prepared.By studying the influence of solution concentration,TBAHP addition amount and applied voltage on the fiber morphology and structure,the optimal process parameters were determined as 20%PA6concentration,0.04mol/L TBAHP,and 30 k V applied voltage,the branching fibers in the nanofiber membrane were the most.The maximum mechanical strength,the minimum average pore diameter and the minimum bulk density were 0.5026μm and0.32 g/m³,respectively.Comprehensive filtration performance analysis showed that when the weight of PA6 MSNFs was 1 g/m²,the average filtration of PA6 MSNFs was99.80%,the filtration resistance was 251 Pa,the quality factor was 0.0248 Pa^-1,and the filtration of particle size 0.25μm and 0.3μm was up to 99.99%and 100.00%,respectively.（2）Pa6&Ag MSNFs with excellent antibacterial performance were prepared,and the filtration efficiency was further improved.Ag NO₃ was selected as an antibacterial agent to be added into the above-mentioned spinning solution to study the effects on conductivity,pore size distribution,stacking structure,antibacterial and filtration performance,and to explore the structural characteristics of the fiber membrane by infrared and XPS.The results show that:When Ag NO₃ is added,the electrical conductivity increases.When the concentration of Ag NO₃ is 0.05 mol/L,the branching fiber covers the largest area,which is conducive to the uniform loading of Ag particles on the fiber surface.When the concentration of Ag NO₃ was 0.1 mol/L,the minimum average pore size was 0.2667μm,and the bulk density increased to 0.54 g/cm³.The antibacterial effect was significant,and the antimicrobial zone radius was 3.12 mm（Staphylococcus aureus）and 3.40 mm（Escherichia coli）,respectively.The results showed that the average filtration efficiency of PA6&Ag MSNFs was higher than that of PA6 MSNFs.With the increase of Ag NO3 concentration,the filtration efficiency of0.2μm particle size was significantly improved.When the concentration is 0.1 mol/L,the filtration performance is the best（filtration efficiency 99.92%,filtration resistance386 Pa）.（3）In order to reduce the filtration resistance,PS/PVDF/PA6&Ag multiscale nanofiber composite membrane with gradient pore structure was prepared.Pa6&ag MSNFs,PVDF NPs and PS MPs were successively compounded on PP nonwovens by electrostatic spinning to obtain PS/PVDF/PA6&Ag multiscale composite membrane filtration material.The filtration performance,overall reusability and antibacterial performance of the composite membrane during spinning time were analyzed.When the spinning time is（20+50+40）min,the average filtration efficiency of PS/PVDF/PA6&Ag multi-scale fiber composite filter material reaches 99.88%,the filtration resistance is 159 Pa,the particle size of 0.0425 Pa^-1,0.2μm,the filtration efficiency reaches 80.00%.After 25 groups of repeated filtration tests,the filtration performance is stable.The antibacterial activity against Staphylococcus aureus and Escherichia coli was 0.33 mm and 0.72 mm,respectively.