| Graphene and graphene oxide have been widely used in various fields due to their excellent properties.In this paper,the effect of physical and chemical structure of graphene oxide on water permeability of membrane and the application of graphene liquid cell were explored.The first chapter introduces the excellent properties of graphene and graphene oxide,and the research status of graphene transfer and graphene oxide membrane in the field of water treatment.In the second chapter,the effect of physical and chemical structure of graphene oxide on the permeability of membrane is introduced.The permeability of graphene oxide membrane to water is the key.The change of oxygen content or interlayer spacing has been widely studied,but the effect of lamellar size remains to be clarified.Here,we fabricated four types of graphene oxide flakes with different physical and chemical structure by modified Hummers method with controlling of temperature.The results showed a sensitive temperature dependence of the size and oxygen content of the graphene oxide flakes.The flake size is negatively correlated with water flux and has a far higher effect on permeation compared with that of the oxygen content.The graphene oxide membrane made of the smallest flakes exhibits ultrahigh water flux of up to 53.7 L m-2 h-1 bar-1,which is more than three times that of conventional large graphene oxide membranes,while still maintaining a high rejection rate of 95.7%for pararosaniline.Importantly,of all pristine graphene oxide membranes without any chemical modifications,this is the most permeable membrane for dyes.Our study reveals a sensitive effect of the physical and chemical structures of graphene oxide on water permeation and represents a facile step regarding ultrahigh flux graphene oxide membranes for water purification.In the third chapter,we introduce the application of graphene liquid cell.We use two single-layer graphene to encapsulate calcium chloride solution,and observe the in-situ dynamic changes of bubbles in the solution under transmission electron microscope.The results show that we have successfully prepared the graphene liquid cell encapsulating calcium chloride solution.The lattice structure of graphene is complete,and the bubbles in calcium chloride solution move slowly without breaking.It shows that graphene is an ideal supporting membrane in the field of transmission electron microscope observation,which can not only protect the high vacuum environment of transmission electron microscope,but also observe the in-situ dynamic change process of liquid samples,which is closely related to the excellent properties of graphene,such as good conductivity,high mechanical strength,high molecular transparency and strong molecular impermeability The structure can be filtered by Fourier filter,and the equipotential surface can eliminate the phase change of electron wave,which is very important in the future exploration of holographic imaging.Finally,the research content of this paper is summarized and prospected. |
