Fabrication And Properties Of Modified TiO₂/spun-bonded And Melt-blown Nonwoven Multifunctional Composite Filter

Design and fabrication of multifunctional filtration materials to remediate indoor air pollution has stimulated wide interests due to severe environmental concern attributed to atmosphere pollutants,mainly including PM_2.5?aerodynamic diameter<2.5 mm?,bacterial virus,and growth of gaseous volatile organic compounds?VOCs?,which have cause dreadful respiratory diseases,baby deformity,leucocythemia,and even cancers.Melt-blown nonwoven material has been widely used in air filtration because of its small fiber diameter,small pore size,large specific surface area and small filtration resistance.However,the poor mechanical property of this material makes it difficult to use it alone as an efficient air filtration material.Spun-bonded nonwoven material has higher strength and superior longitudinal and transverse properties than other nonwovens.Combining these two materials into a spun-bonded and melt-blown?SM?nonwoven composite air filter material,just to make up for their own defects,not only has high strength,good wear resistance,but also has good filtration performance.In order to simultaneously improve removability of VOCs and bacteria in air,we introduced TiO₂ NPs which had strong catalytic activity.TiO₂ has good chemical stability,pretty high photocatalysis activity,nontoxicity,and good biocompatability,so as to attract growing interests to be used to degrade VOCs in atmosphere.In this work,we have demonstrated a facile strategy to achieve a multifunctional SM filter which has high filtration efficiency for PM2.5 and good degradation for VOCs and bacteria simultaneously.After mixing Ag/TiO₂ into P25 TiO₂,the nanoparticle mixtures were thoroughly deposited on polypropylene fiber surface on each layer of melt-blown nonwoven via online spray.On the other hand,the NPs mixtures were loaded onto polyethylene/polyester sheath/core bicomponent fiber spun-bondednonwoven by offline spray and heat treatment.By thermal combination,a hierarchically structured Ag/TiO₂ nanoparticle based SM nonwoven were prepared.Through the characterization and testing of the material,the following conclusions can be drawn.?1?Through the single factor experiment,it could be seen that with the decrease of DCD,polymer extrusion and the increase of air pressure,both the filtration efficiency and filtration resistance tended to increase.Orthogonal test shows that the hot air pressure was the most important factor influencing the structural performance and filtration performance of the melt-blown material,the DCD was the second and the impact of polymer extrusion quantity was the least.When DCD,air pressure and velocity of the polymer extrusion arrived 150mm,0.4MPa,and 15 g·min^-1,respectivly,optimum value of the PP melt blown nonwoven layer could be obtained.?2?TiO₂ NPs were successfully loaded onto SM nonwovens by online-offline spray and dispersed evenly on the surface of the fibers or at the interface between the fibers.In addition,TiO₂/SM porous composites had higher photocatalytic activity than TiO₂ NPs.?3?The Spun-bonded nonwoven material had much higher strength than the melt-blown nonwoven layer,combining two layers could greatly increase the mechanical properties of melt-blown materials.After loading a certain amount of TiO₂ NPs,the tensile strength of the composites decreased slightly.?4?The filtration efficiency,photocatalytic activity and antibacterial activity of TiO₂/SM composite filter increased with the increase of TiO₂ loading on the melt-blown layer?M?and the spun-bonded layer?S?.When the load was ST20/MT15,the quality factor of composite filter reached the maximum,the comprehensive filtering performance of filter material reached the best and the antibacterial properties is excellent under the UV light irradiation.The composite filter achieved the best overall air purification performance.To sum up,TiO₂/SM multi-functional composite filter material was prepared by online-offline spraying method.The method had the advantages of high speed,large output,simple process and high labor productivity,and had application potentail in industrial production.