Preparation And Characterization Of Graphene Grafted Polymer Separation Membranes

With the improvement of living standards,people have higher and higher requirements for living environment,and people are increasingly pursuing a living environment with clear water and green mountains.Prevention and control of environmental pollution has become the due meaning of social governance.The development of society is inevitably accompanied by the development of industry,which will inevitably produce a large number of industrial waste water,among which dye wastewater is one of them.This paper provides a treatment method for dye wastewater.Taking graphene-based materials as the entry point,the graphene-based materials are modified to prepare separation membranes for dye separation and reduce the pollution of dye wastewater to the environment by using many excellent properties of graphene-based materials.Researchers have developed a number of ways to modify graphene-based separation membranes.Among them,it is widely used to enhance the permeability flux and separation performance of graphene-based separation membranes by doping other substances,which is also a relatively simple and easy to operate method.However,the problems of poor stability and narrow application range of graphene-based separation membranes have not been reasonably solved.Therefore,in this paper,the stability of graphene-based separation membranes was improved by grafting cross-linking,and the grafting of p H responsive polymer chains could not only broaden the application range of graphene-based separation membranes,but also improve the separation performance of dyes in the separation membranes.In this paper,a variety of characterization methods are used to test membrane materials and properties,and the separation performance of different types of dyes is systematically discussed in detail.The specific content is divided into three parts:（1）First,GO was prepared by a modified Hummers process,then GO was modified by vinyl triethoxysilane（VTES）to obtain GO-VTES with double bonds introduced on the surface,and then polyacrylic acid（PAA）was grafted onto GO-VTES.Preparation of graphene oxide（GO-PAA）grafted polyacrylic acid chains.The separation properties of GO-PAA separation membrane on anionic dyes and cationic dyes,and the effects of p H and amount of acrylic acid on the separation of dyes were investigated.GO-PAA separation membrane showed a high separation efficiency of 99%for anionic dyes and cationic dyes.The separation effect of GO-PAA composite membrane is particularly good under alkaline conditions.（2）On the basis of the GO-VTES prepared in（1）,two cationic monomers,diallyl dimethyl ammonium chloride（DDA）,allyl trimethyl ammonium chloride（ATA）and acrylamide（AM）,were selected.The separation properties of GO-PDDA and GO-P（ATA-co-AM）separation membranes on anionic dyes and cationic dyes,and the effects of p H and monomer amount on the separation of dyes were investigated.The separation membranes GO-PDDA and GO-P（ATA-co-AM）have the intercession effect of more than 93%on cationic dyes,and the adsorption and separation effect on anionic dyes is more than 91%.The highest water permeability is 326.43 L·m^-2·h^-1·bar^-1.（3）Finally,on the basis of the above experiments,we prepared graphene quantum dots（GQDs）with GO as the precursor,also modified GQDs-VTES to obtain GQDs-VTES,and then grafted polyacrylic acid onto the modified graphene quantum dots to obtain GQDS-PAA.The effect of adding amount of acrylic acid and grafting density on dye separation was investigated.GQDs-PAA separation membranes were prepared by vacuum filtration.The adsorption and separation effect of GQDs-PAA1.5 on corundum red（CR）was 90%,and Rhodamine B（Rh B）was 85%.The highest permeability of pure water was 99.27～118.73 L·m^-2·h^-1·bar^-1 under different graft densities of PAA.