Structure Control Of Graphene Oxide Membrane And Its Application In Water Treatment And Biological Sterilization

Graphene oxide membranes stand out among various water treatment membranes due to their unique two-dimensional structure,easy stacking of single atoms,strong dispersibility in water,simple preparation process,and low price.Graphene oxide is a derivative of graphene.There are a large number of oxygen-containing groups,such as epoxy,hydroxyl,and carboxyl groups,distributed on the surface and edge of the substrate.These groups make graphene oxide have good hydrophilicity and solubility in solvents.In terms of water purification and desalination:it is widely used as a water purification matrix membrane.However,in practical applications,there is a contradiction between the ion rejection rate of the graphene oxide membrane and the water flux.How to solve this contradiction has become a hot issue for everyone to study.Compared with the displacement or penetration membrane of other zero-dimensional or one-dimensional nanomaterials,graphene has antibacterial activity.People have also conducted a lot of research on the antibacterial activity of functionalized graphene,but it is found that functionalized graphene has less than twice the antibacterial activity enhancement of graphene.Therefore,it is an urgent need and challenge to develop a new antibacterial material or reagent to counteract the increasing resistance of bacteria and achieve selective,efficient and environmentally friendly antibacterial activity.In this paper,the purification and desalination of water:Mainly developed a sort of GO membrane with an ultrahigh water permeance while still maintaining a high rejection rate of multivalent metal ions.In particular,the permeance reaches an unprecedented 75±2 L m^-2 h^-1 bar^-1,while maintaining the high rejection rate of 99.9±0.1%.The ultrahigh water permeances are attributed to the larger interlayer spacings of the GO membranes resulting from the lack of the drying treatment during the fabrication process.Moreover,the GO membranes in the present work showed outstanding stability with superior performance.In addition,we found that Zn SO4-controlled GO membranes and Fe Cl3-controlled GO membranes have different rejection performance,because the ions can control and fix the interlayer spacings of the GO membranes due,and thus the controlled ions potentially exclude other cations that require a larger interlayer spacing,or allow other hydrated cations with smaller sizes to pass through.Overall,our findings reveal the beauty of GO membranes in the multivalent ions rejection and ion screening.In addition,we develop a pure r GO membrane reduced by a facile amino-hydrothermal method（AH-r GO）that achieves an ultrahigh permeance while maintaining an effective ion rejection rate for multivalent metal ions.The permeance of the AH-r GO membranes with a thickness of～160 nm reaches up to 142.5 L m^-2 h^-1 bar^-1,with corresponding ion rejection of 91.6%.The‘trade-off’between ions rejection and permeability can be tuned by membrane thickness to achieve high rejections of 99.9%for Fe Cl₃,Al Cl₃,Cr Cl₃,Cu SO₄,Zn SO₄,and Pb（NO₃）₂,with still high water permeance.X-ray diffraction and X-ray photoelectron spectroscopy（XPS）experiments reveal that water channel of AH-r GO not only has the characteristics of r GO--smaller interlayer spacing and stability in the water,but also maintains another larger interlayer spacing as water channel like GO membrane,resulting in ultrahigh water permeance.Thus,we think that our findings represent a facile step towards ultrahigh permeance,effective rejection and stable performance of pure r GO membranes for multivalent metal ions.In terms of the biological functions of graphene:we prepared a reduced graphene oxide copper composite material（r GO-Cu）by reducing the adsorption and enrichment of copper ions on graphene oxide.The reduced graphene oxide copper composite material（r GO-Cu）is Gram-negative Escherichia coli（E.coli）has significant selective antibacterial activity.By reducing the adsorption function of graphene oxide to copper ions,the concentration of copper ions in the filtrate is kept at an extremely low level.What’s more exciting is that the antibacterial activity of the resulting r GO-Cu composite is two orders of magnitude higher than that of a single copper ion.The reduced graphene oxide functionalized with copper ions shown in this paper achieves significant selective antibacterial activity,while avoiding environmental hazards,and provides guidance for the design of high-efficiency selective antibacterial activity.Considering the scalability of production and the simplicity of removing reduced graphene oxide by centrifugation or filtration.The antibacterial activity of the reduced graphene oxide functionalized by copper ions represents a wider range of applications in realizing practical applications such as cheap,simple,efficient and environmentally friendly antibacterial.