Preparation And Properties Of Mixed Matrix Films Based On Graphene Oxide

With the rapid development of society and economy and improvement of economic profits resulted from large-scale industrial production,the direct discharge of industrial waste water threatens the balance of natural ecology.Because of the advantages of low energy consumption and high separation efficiency,membrane separation technology has played an increasingly important role in the field of seawater desalination,industrial wastewater purification and so on.Organic polymer is an important separation membrane material,but in practical application,the organic polymer membrane has low mechanical strength and poor anti pollution ability,which restricts its wide application in water treatment.Graphene oxide(GO)as an important derivative graphene.not only possesses the excellent mechanical and thermal properties like grapheme,but also contains groups such as hydroxyl,carboxyl,epoxy groups after oxidation.The presence of these polar oxygen containing groups makes GO highly hydrophilic.Therefore.it is very suitable to be used as inorganic nano particles to add to the organic polymer membrane materials,to produce mixed matrix membrane,and then improves the properties of the membrane materials.This paper firstly uses GO as the inorganic nano additives to mix with polyvinyl alcohol(PVA)and polyphenylene sulfone(PPSU)respectively in order to change its properties.Then it adopts the immersion precipitation phase inversion method to produce organic-inorganic mixed matrix membrane and finally apply the products to the treatment of methyl violet with benzene ring structure in dye wastewater.The main research contents are as follows:(1)Graphite oxide is prepared by using the advanced Hummers method,and then graphene oxide suspension is obtained by dispersing via high frequency ultrasound.Scanning electron microscope(SEM),infrared spectroscopy(FTIR),X-ray diffraction(XRD)and thermo-gravimetric(TGA),and other means are used to conduct a series of performance characterization,and the results show that the graphite oxide after ultrasonic dispersion of graphene oxide is single layer structure,the carbon network surface of GO introduced a number of carboxyl,epoxy groups and hydroxyl oxygen containing functional groups,that are strong hydrophilic.GO dispersion can be stored with stable properties at room.at the same time,the mechanism of membrane formation after adding GO is also discussed.(2)PVA/GO mixed matrix membrane is prepared by immersion precipitation phase inversion method.The effects of solvent type.PVA concentration,GO content and PEG content on the thermal stability,hydrophilicity,separation performance and anti fouling property of the mixed matrix membrane are investigated.The experimental results show that when using deionized water as solvent,PVA and PEG concentration are mixed matrix membrane 10%,GO dosage of 2wt%preparation,membrane has the best tensile strength and anti pollution ability,and has a good removal effect on wastewater solution methyl violet dyes.The membrane interception rate can reach 88.7%after two times of cleaning through BAS solution pollution.(3)In order to further expand the application range of graphene oxide in organic polymer membrane,PPSU/GO mixed matrix membrane is prepared.PPSU as the membrane material is expensive,In order to reduce the cost,then the excellent performance of PPSU is synthesized by changing the solvent using the nucleophilic substitution reaction.Then PPSU/GO membrane is prepared by immersion precipitation phase inversion method.Mixed matrix membrane's contact angle,water flux,the determination of bovine serum albumin(BAS)rejection and flux recovery performance rate are determined,and the microstructure of the membrane is characterized by SEM.With the addition of GO,the pure water flux increases gradually and reaches increased to 254.9 L·m-2·h-1 when GO content is 2wt%,at the same time the membrane pyrolysis temperature reached 481.9?,88? higher than the pure PPSU membrane,The addition of GO,the mechanical of the mixed matrix membrane is also increased,but when the GO content is greater than 1.5wt%,the transverse pore structure is formed in the membrane by SEM,so the elongation at break began to decrease.When the amount of GO is 1.5wt%,PPSU/GO mixed matrix membrane anti fouling ability achieves optimal,and flux recovery rate reaches 86%,the total number of membrane pollution and pollution parameters is reduced,at the same time has a retention effect on the methyl violet liquid to some extent..In conclusion,GO is rich in oxygen containing hydrophilic functional groups and smooth surface of atomic scale,if blended into organic membrane materials,the preparation of the mixed matrix membrane has excellent thermodynamic stability and anti fouling ability,which will broaden the thinking of the polymer membrane materials in the future.