Preparation Of Graphene Oxide Composite Membrane And Its Application In Industrial Wastewater Treatment

Graphene oxide(GO)is a new two-dimensional material.It can be vacuum-filtered,spray-coated,spin-coated,and self-assembled to form a layered structural film.Except for the existence of the channel of the GO membrane,the expanded channels such as the wrinkles of the edge gap,the nanopore between the membranes and the functional groups on the surface of the sheet provide fast and selective transport paths,which show excellent prospects in the field of membrane treatment of industrial wastewater.However,the pure GO membrane has a large amount of hydrophilic oxygen-containing functional groups on its surface,and the sheet stack is dense,which causes it easy to swell in an aqueous solution,and the flux is low.Additionally,the high preparation cost of the GO membrane and the complicated preparation method also limit its practical application.In this paper,the ceramic support GO/AC composite film was prepared by inserting activated carbon(AC)into the GO layer by vacuum suction-sintering method with Al2O3 ceramics as the substrate.The spacing of channels between the GO layers was expanded by AC.The pure water flux,wastewater separation performance and stability of the composite membrane were investigated.The results show that the pure water flux of the GO/AC composite membrane is nearly 300 times higher than that of the pure GO membrane,and also for rhodamine B(99.5%),Congo red(99.3%),methylene blue(92.8%),methyl orange(81.5%)dye wastewater has a good removal effect,but the removal effect of copper ion wastewater(2%?27%)is not good.The reason is that the block structure of AC makes the size of the pores in the composite membrane too large to intercept the ion wastewater that are in small molecular scale.In order to solve the problem that the GO/AC composite membrane could not handle the ion wastewater,the attapulgite(ATP)with needle or rod structure was used as the fillers,and the GO/ATP composite membrane was successfully prepared by vacuum suction-sintering on the surface of the ceramic substrate.After 60 days of water immersion test,the composite film prepared by sintering at 170? possesses good adhesion with the substrate.Compared with GO membrane,the water flux of GO/ATP composite membrane increased by 14.75 times,and it has excellent separation effect on Cu2+(99.9%),Ni2+(97.2%),Pb2+(99.9%)and Cd2+(99.9%)simulated wastewater solutions.After soaking GO/ATP composite membrane in water for 60 days,the composite membrane was firmly bonded to the ceramic substrate,and the removal rate of the Cu2+solution(100 mg/L)was maintained above 99.9%in the 54 h filtration test.The GO/ATP composite film sintered at 170? increases the adhesion of the film to the substrate,but the sintering method leads to a decrease in the number of oxygen-containing functional groups of GO,and the preparation process is complicated.In response to this problem,this paper attempts to pretreat the ceramic matrix and add polyvinyl alcohol(PVA),in order to use its adhesive action to increase the bonding force between the film and the substrate,also successfully prepared GO/ATP/PVA composite membrane by vacuum filtration-drying method.Compared with the GO/ATP composite membrane prepared by sintering method,the bonding force between the GO/ATP/PVA composite membrane and the matrix is almost same,and the pure water flux is about 3.3 times of the GO/ATP composite membrane,and GO/ATP/PVA composite membrane has good separation effect on Cu2+(99.2%),Ni2+(96.9%),Pb2+(98.9%),and Cd2+(97.2%)solutions.In a word,the new as-synthesized composite membrane while maintains the high removal rate of heavy metal ions,meanwhile the interlayer spacing was increased without sintering,and the pure water flux was improved.