Study On Preparation And Filtration Performance Of PSA-based Composite Filtration Membrane

At present,China is at the historical intersection of the two centenary Goals.With the rapid development of economy and industrialization,power plant,chemical industry,steel,transportation and other industries have not only promoted social progress,but also caused increasingly severe environmental problems,requiring a means of filtration and purification to reduce the discharge and treatment of pollutants.Based on this background,this paper discusses the preparation of a new nano fiber filtration membrane,in order to provide reference for solving the problems of air pollution and water pollution.In this paper,Polysulfonamide/Polyurethane（PSA/TPU）composite film was prepared by electrostatic spinning method,which can withstand the high temperature environment of more than 200℃.The effects of PSA/TPU ratio on the morphology and properties of the composite films were investigated.Nanofibers with different diametres from 106.68±0.85 nm to 277.81±4.72 nm were obtained.The fibers observed by scanning electron microscope（SEM）are smooth and well-proportioned,and the characteristic peaks observed by FTIR after successful introduction of TPU are located at 2940 and 2850 cm^-1.Thermogrgravity analysis（TGA）shows that the decomposition weight loss of composite films begins above 230℃.The decomposition temperature of PSA is above 400℃.The stress and strain test showed that the maximum stress and elongation at break of the composite film reached 13.66±1.43 MPa and 75.01±3.78%,respectively,after adding TPU component.In addition,the filtration application of the composite membrane was tested.The filtration results show that the composite membrane has a high filtration efficiency for diethylhexylsebacate（DEHS）and sodium chloride（Na Cl）aerosol particles at the flow velocity of 32 L/min（>99%）and lower pressure drop（80 Pa）.Therefore,PSA/TPU composite membrane is a promising candidate material for high temperature filtration.At the same time,this paper successfully developed a unique layered composite nanofiber membrane,which is composed of zeolite imidazolium ester skeleton-8-embedded polyethersulfone（PES@ZIF8）fiber layer and polysulfone amide/polyethersulfone（PSA/PES）fiber layer,to cope with the complex environment in the actual filtration/separation process.Overcome the contradiction between high filtration efficiency and low pressure resistance.When PES concentration was 32 wt%and spinning voltage was 25 k V,the average fiber diameter of PES@ZIF8 layer decreased from 780±18 nm to 390±20 nm with the increase of ZIF8 particle concentration from 0 wt%to9wt%,while PSA/PES layer had smaller fiber diameter.The minimum is 157.8nm.Due to the synergistic effect of multiple components and the advantages of double layered structure,the integrated PES@ZIF8-PSA/PES filter has super PM_0.3purification capacity（close to 99.95%）under very low pressure drop（only 15 Pa）,long-term use performance,the real smoke PM_2.5can be purification from>800 to<10μg/m³.At the same time,it has high temperature resistance（it can still keep its original morphology characteristics after baking at 200℃for 1 h）,flame retardant performance（no burning phenomenon after9 s near the fire source）,good chemical stability（after being treated with p H=1 and p H=13 acid/alkali solution 1 h can still maintain good morphology and filtration performance）,good light transmittance and strong self-cleaning ability.In addition,due to its selective wettability（including hydrophobicity and superlipophilicity）,it achieves effective separation of oil-water mixtures and oil-water emulsions.The separation efficiency of oil/water,oil/acid,oleo-alkali and oil/salt mixtures is 98.53±0.12%,98.50±0.10%,98.49±0.09%and 98.43±0.13%,respectively.PES@ZIF8-PSA/PES nanofiber membranes maintain excellent air filtration and oil/water separation performance even under high temperature or strong acid/alkali conditions.This special comprehensive performance endows PES@ZIF8-PSA/PES composite membrane with wider application prospects in the fields of environmental governance,personal protection and industrial safety.