| Smoke pollution and heavy metal ion pollution are global problems that endanger public health.Cigarette smoke is aerosol composed by a lot of solid,volatile and semi-volatile matter after a series of physical and chemical reactions.Over 1200 materials have been reported in smoke.Nowadays,commercial CA cigarette filters could not prevent all the smoke from entering human body.China is still in the stage of economic development with a large amount of industrial waste water to be treated.The heavy metals contain in wastewater and enter the body through water or plants,which have great impacts on human health.Waste water treatment methods are unpractical,such as sedimentation,chemisorption.Electrospinning fibrous membrane is an ideal absorbing material with small fiber diameter,large surface area and high porosity.Electrospinning fibrous membranes with larger surface area,greater pore volume and higher porosity can be obtained by varying parameters of spinning solution and environment.These advantages of fibrous membranes can increase contact area and improve the adsorption properties.This paper focused on the problems of smoke and heavy metal ion pollution and explored the effects of fiber structures on adsorption properties.In addition,the mechanism of smoke and heavy metal adsorption were studied and provided theoretical support for our studies.(1)The preparation of porous and hollow PLA fibers.In the single needle electrostatic spinning,7wt% PLA spinning solution were pushed at the rate of 1m L/h,the voltage was 16 k V and the distance between needle and collector were 12 cm.When the relative humidity were higher than 45%,pores appeared on the surface of fibers.In the coaxial electrostatic spinning,7wt% PLA spinning solution was used as core solution and 2 wt% PVA spinning solution was used as shell solution.Core solution was pushed at the rate of 0.7m L/h,shell solution was pushed at the rate of 0.2m L/h.The voltage was 23 k V and the distance between needle and collector were 12 cm.hollow structure appeared when the DMSO/DCM ratio was 2:1.(2)The mechanism and effect of smoke adsorption properties.Firstly,the mechanism of smoke adsorption properties was analyzed.The adsorption of the PLA fibrous membrane on nicotine and tar depend mainly on the hydrophilic and fibrous membrane pores of the PLA.The adsorption of water is mainly dependent on the condensation of water vapor on the surface of the fiber and the unbalance of the surface molecules.The adsorption of carbon monoxide mainly depends on the adsorption field of pores.Secondly,Compared with the smooth surface of PLA fiber membrane,the porous structure of the fiber surface can effectively increase the adsorption efficiency of the fiber membrane,reduce the absorption resistance and improve the adsorption effect.When exposed to the front of the filter,the adsorption of the porous fibrous membrane on nicotine,tar and water increased by 2.1%,0.3% and 6.4%.When exposed to the back of the filter,the adsorption of the porous fibrous membrane on nicotine,tar and water increased by 2.7%,1.1% and 6.4%.Compared with porous PLA fiber membrane,hollow structure of the fiber can offer larger storage space for gas adsorption and larger contact area,to further increase the fiber membrane adsorption efficiency,reduce the suction resistance.The adsorption of the hollow porous nanofiber membrane on nicotine,tar and water increased by 3.8%,6.2%,0.9% and 6.0%,when placed in the front of the filter.When exposed to the back of the filter,the absorption of nicotine,tar and water by hollow porous nanofiber membrane was reduced due to the effect of airflow.(3)The mechanism and effect of Cu2+ adsorption properties.PLA fibers could keep the form when the adsorbing time was 20 min,solution concentration was 1000 ppm and the adsorbing temperature was 80 ?by observing the morphology before and after adsorbing.Compared with the surface smooth fiber membrane,the adsorption effect of PLA-45,PLA-60 surface porous fiber membrane on Cu2+ increased,and the adsorption capacity increased by 9.5% and 25.4% respectively.Compared with the surface porous fiber membrane,the adsorption capacity of the PLA-45-1 and PLA-45-2 hollow porous fiber membrane increased by 120.4% and 150.3% respectively. |
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