Method for preparing graphene oxide film and graphene oxide film

Abstract

The embodiment of the invention relates to the technical field of membrane preparation, in particular to a method for preparing a graphene oxide membrane and the graphene oxide membrane, and the method mainly comprises the following steps: oxidizing graphite powder; mixing the oxidized graphite powder with deionized water to obtain a first mixed solution; obtaining a graphite phase carbon nitride dispersion liquid; mixing the obtained first mixed solution with the obtained graphite phase carbon nitride dispersion solution to obtain a second mixed solution; depositing the second mixed solution on a filter membrane; drying the filter membrane deposited with the second mixed solution; and separating from the filtering membrane to obtain the graphene oxide membrane. In the embodiment of the invention, the first mixed liquid and the graphite phase carbon nitride dispersion liquid are mixed, and the graphite phase carbon nitride material can be inserted into the interlayer structure of the graphene oxide in a layer-by-layer stacking manner, so that the separation factor and permeation rate of the graphene oxide membrane to hydrogen isotopes are improved; furthermore, the hydrogen isotope water separation performance of the graphene oxide membrane is comprehensively improved.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of membrane preparation, and specifically to a method for preparing a graphene oxide membrane and a graphene oxide membrane. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] Graphene oxide membrane is a layered membrane formed by stacking graphene oxide nanosheets. Graphene oxide membrane has high water flux, controllable interlayer spacing and efficient separation performance, which can make water molecules flow quickly between graphene oxide membrane layers and effectively intercept pollutants in water. In addition, graphene oxide membrane also shows excellent chemical stability and can adapt to various complex chemical environments, making it potential for application in the field of waste liquid treatment. Summary of the invention

[0004] A brief overview of the present application is provided below in order to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a graphene oxide film, which comprises the following steps: S10: obtaining graphite powder and deionized water; S20: oxidizing the graphite powder obtained in step S10; S30: mixing the oxidized graphite powder and the deionized water obtained in step S10 to obtain a first mixed liquid; S40: obtaining a graphite phase carbon nitride dispersion; S50: mixing the first mixed liquid obtained in step S30 with the graphite phase carbon nitride dispersion obtained in step S40 to obtain a second mixed liquid; S60: depositing the second mixed liquid on a filter membrane; S70: drying the filter membrane on which the second mixed liquid is deposited; S80: separating the graphene oxide film from the filter membrane.

[0006] In the embodiment of the present application, a second mixed solution is obtained by mixing a first mixed solution with a graphite phase carbon nitride dispersion, and the graphite phase carbon nitride material and graphene oxide are fully mixed in the second mixed solution. When the second mixed solution is deposited on the filter membrane, the graphite phase carbon nitride material can be inserted into the interlayer structure of the graphene oxide film in a layered manner, thereby retaining the original physical and chemical properties of the graphene oxide film, such as stable, easy to prepare, good hydrophilicity and mechanical properties. At the same time, by doping with the graphite phase carbon nitride material, the separation factor of the graphene oxide film for hydrogen isotopes is significantly improved, and the permeation rate of hydrogen isotopes is accelerated, thereby comprehensively improving the hydrogen isotope water separation performance of the graphene oxide film.

[0007] In a second aspect, an embodiment of the present application further provides a graphene oxide film, which is prepared using the method for preparing a graphene oxide film provided in the first aspect of the present application.

[0008] In the embodiments of the present application, by introducing graphite phase carbon nitride material into the interlayer structure of the graphene oxide membrane, the separation factor and permeation rate of the graphene oxide membrane for hydrogen isotopes are significantly improved, thereby improving the hydrogen isotope water separation performance of the graphene oxide membrane as a whole, so that the graphene oxide membrane can quickly and accurately separate the target hydrogen isotopes in the hydrogen isotope water separation experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Other objects and advantages of the present application will become apparent from the following description of the embodiments of the present application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of the present application.

[0010] Figure 1 It is a flow chart of a method for preparing a graphene oxide film according to one embodiment of the present application.

[0011] Figure 2 This is a scanning electron microscope morphology image of a cross section of a graphene oxide film according to an embodiment of the present application.

[0012] Figure 3 is an X-ray diffraction spectrum of a graphene oxide film according to an embodiment of the present application.

[0013] Figure 4 This is an X-ray photoelectron spectroscopy spectrum of a graphene oxide film according to an embodiment of the present application.

[0014] Figure 5 This is the X-ray photoelectron spectroscopy spectrum of graphene oxide film without graphite phase carbon nitride material.

[0015] Figure 6 4 is a relationship diagram of the separation factor, permeation rate and doping amount of a graphene oxide membrane according to an embodiment of the present application.

[0016] Description of reference numerals:

[0017] 10. Carboxyl peak;

[0018] 20, carbonyl peak;

[0019] 30. Fitting peaks of carbon-nitrogen bonds and hydroxyl groups;

[0020] 40. sp 3 Hybridized carbon peak;

[0021] 50. sp 2 Hybridized carbon peak;

[0022] 60. Hydroxyl peak.

[0023] It should be noted that the drawings are not necessarily drawn to scale, but are merely shown in a schematic manner that does not affect the reader's understanding. DETAILED DESCRIPTION

[0024] Exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the content of this application.

[0025] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present application are shown in the accompanying drawings, while other details that are not very relevant to the present application are omitted.

[0026] The inventors of the present application have found that with the continuous development of the nuclear industry, a large amount of radioactive tritium has accumulated in the reactor coolant and post-processing waste liquid of nuclear power plants. Direct discharge of tritium-containing waste liquid will have serious impacts on the human body and the environment. Therefore, it is necessary to effectively treat the tritium-containing waste liquid to reduce its adverse effects. Hydrogen isotope separation technology is the key to treating tritium-containing waste liquid. However, existing hydrogen isotope separation technologies generally have problems such as huge energy consumption, low separation efficiency and poor method reproducibility.

[0027] Based on this, an embodiment of the present application provides a method for preparing a graphene oxide film. Figure 1 FIG. 1 is a flow chart of a method for preparing a graphene oxide film according to an embodiment of the present application. Figure 1As shown, it includes the following steps: S10: obtaining graphite powder and deionized water; S20: oxidizing the graphite powder obtained in step S10; S30: mixing the oxidized graphite powder and the deionized water obtained in step S10 to obtain a first mixed solution; S40: obtaining a graphite phase carbon nitride dispersion; S50: mixing the first mixed solution obtained in step S30 with the graphite phase carbon nitride dispersion obtained in step S40 to obtain a second mixed solution; S60: depositing the second mixed solution on a filter membrane; S70: drying the filter membrane on which the second mixed solution is deposited; S80: separating from the filter membrane to obtain an oxide graphene membrane.

[0028] In the embodiment of the present application, a second mixed solution is obtained by mixing a first mixed solution with a graphite phase carbon nitride dispersion, and the graphite phase carbon nitride material and graphene oxide are fully mixed in the second mixed solution. When the second mixed solution is deposited on the filter membrane, the graphite phase carbon nitride material can be inserted into the interlayer structure of the graphene oxide film in a layered manner, thereby retaining the original physical and chemical properties of the graphene oxide film, such as stable, easy to prepare, good hydrophilicity and mechanical properties. At the same time, by doping with the graphite phase carbon nitride material, the separation factor of the graphene oxide film for hydrogen isotopes is significantly improved, and the permeation rate of hydrogen isotopes is accelerated, thereby comprehensively improving the hydrogen isotope water separation performance of the graphene oxide film.

[0029] In some embodiments, in step S50, the mass concentration of the first mixed liquid is 1.5-2.5 mg / ml, and the mass concentration of the graphite phase carbon nitride dispersion is 0.1-0.2 mg / ml.

[0030] In the embodiments of the present application, by setting the mass concentration ranges of the first mixed liquid and the graphite-phase carbon nitride dispersion, the performance of the mixture after the first mixed liquid and the graphite-phase carbon nitride dispersion are mixed can better meet the requirements.

[0031] In some preferred embodiments, the mass concentration of the first mixed liquid is 2 mg / ml, and the mass concentration of the graphite phase carbon nitride dispersion is 0.18 mg / ml.

[0032] In some embodiments, in step S50, the mass percentage of graphite-phase carbon nitride in the second mixed solution is 1.8% to 8.3%.

[0033] In an embodiment of the present application, the mass proportion of graphite phase carbon nitride in the second mixed liquid is set to limit the mass proportion of graphite phase carbon nitride in the graphene oxide film, so as to ensure that the obtained graphene oxide film has excellent hydrogen isotope water separation performance.

[0034] In some embodiments, the mass percentage of graphite-phase carbon nitride in the second mixed liquid may be 1.8%, 3.5%, 5.1%, 6.7%, or 8.3%.

[0035] In some preferred embodiments, the mass proportion of graphite-phase carbon nitride in the second mixed liquid is 6.7%.

[0036] In some embodiments, the mass ratio of graphite-phase carbon nitride in the second mixed solution is consistent with the mass ratio of graphite-phase carbon nitride in the graphene oxide film.

[0037] In some embodiments, the mass of graphene oxide in the second mixed solution is 10 mg.

[0038] In some embodiments, step S50 further includes subjecting the second mixed liquid to ultrasonic treatment using an ultrasonic machine to mix the second mixed liquid uniformly.

[0039] In an embodiment of the present application, the second mixed liquid is ultrasonically treated by an ultrasonic machine, so that the graphene oxide nanosheets in the first mixed liquid and the graphite phase carbon nitride nanosheets in the graphite phase carbon nitride dispersion are fully exfoliated and evenly dispersed in the second mixed liquid, thereby ensuring that during the deposition of the second mixed liquid, the graphite phase carbon nitride can be inserted into the interlayer structure of the graphene oxide film in the form of stacked layers, avoiding the granular graphite phase carbon nitride from being embedded in the interlayer of the graphene oxide film due to unevenness, thereby destroying the complete layer-by-layer stacking structure in the graphene oxide film.

[0040] In some embodiments, the ultrasonic time may be 30 minutes to ensure that the graphene oxide nanosheets and the graphite-phase carbon nitride nanosheets can be fully mixed in the second mixed liquid.

[0041] In some embodiments, in step S60, the second mixed solution is deposited on the filter membrane by vacuum filtration.

[0042] In an embodiment of the present application, the graphene oxide nanosheets and the graphite phase carbon nitride nanosheets in the second mixed liquid can be alternately deposited on the filter membrane by vacuum filtration, so that the graphite phase carbon nitride nanosheets can be inserted into the graphene oxide nanosheets in a layer-by-layer stacking manner, thereby forming graphene oxide films containing graphite phase carbon nitride of different thicknesses on the filter membrane.

[0043] In some embodiments, in step S70, drying is performed at room temperature.

[0044] In some embodiments, in step S70, the drying time is 10-12 hours.

[0045] In the embodiments of the present application, by drying the filter membrane formed with the graphene oxide membrane for 10-12 hours at room temperature, the moisture on the surface of the filter membrane can be effectively removed, preventing the moisture on the surface of the filter membrane from interfering with the separation of the graphene oxide membrane and the filter membrane, thereby ensuring that a graphene oxide membrane with a complete layered structure can be obtained.

[0046] In some preferred embodiments, in step S70, the drying time is 12 hours.

[0047] In some embodiments, in step S20, after the reaction is completed, deionized water and peroxide are added to the reactants to terminate the reaction.

[0048] In the embodiments of the present application, deionized water and peroxide are added to the oxidized graphite powder, which can quickly terminate the oxidation reaction of the graphite powder, thereby avoiding damage to the structure of the graphite powder due to excessive oxidation.

[0049] In some embodiments, the peroxide may be hydrogen peroxide.

[0050] In some embodiments, 570 ml of deionized water and 16 ml of hydrogen peroxide may be added to terminate the reaction.

[0051] In some embodiments, in step S20, a predetermined amount of concentrated sulfuric acid, a predetermined amount of potassium permanganate, a predetermined amount of sodium nitrate, and a predetermined amount of deionized water are used to oxidize the graphite powder.

[0052] In the embodiments of the present application, by setting the predetermined contents of concentrated sulfuric acid, potassium permanganate, sodium nitrate and deionized water, the oxidation degree and oxidation process of the graphite powder are controlled, the oxidation efficiency of the graphite powder is improved, and the waste of concentrated sulfuric acid, potassium permanganate, sodium nitrate and deionized water is avoided, thereby saving the oxidation cost of the graphite powder.

[0053] In some preferred embodiments, the concentrated sulfuric acid may be 92 ml, the potassium permanganate may be 12 g, the sodium nitrate may be 2 g, and the deionized water may be 200 ml.

[0054] In some embodiments, step S30 also includes: washing the oxidized graphite powder to remove impurities remaining on the oxidized graphite powder; vacuum filtering the washed oxidized graphite powder to obtain pure oxidized graphite powder; mixing the pure oxidized graphite powder with deionized water to obtain a first mixed solution; and ultrasonicating the first mixed solution with an ultrasonic machine to peel off the oxidized graphite powder into oxidized graphene nanosheets and evenly disperse them in the first mixed solution.

[0055] In some embodiments, the filter membrane is aluminum oxide to ensure that graphene oxide nanosheets and graphite-phase carbon nitride nanosheets can be alternately deposited on the filter membrane.

[0056] An embodiment of the present application also provides a graphene oxide film, which is prepared using the method for preparing a graphene oxide film provided in the first aspect of the present application.

[0057] In the embodiments of the present application, by introducing graphite phase carbon nitride material into the interlayer structure of the graphene oxide membrane, the separation factor and permeation rate of the graphene oxide membrane for hydrogen isotopes are significantly improved, thereby improving the hydrogen isotope water separation performance of the graphene oxide membrane as a whole, so that the graphene oxide membrane can quickly and accurately separate the target hydrogen isotopes in the hydrogen isotope water separation experiment.

[0058] The following is a specific example to further illustrate the process of preparing graphene oxide film using the method in this application.

[0059] Weigh 2 g of graphite powder, add 92 ml of concentrated sulfuric acid, 12 g of potassium permanganate, 2 g of sodium nitrate and 200 ml of deionized water to the graphite powder to fully oxidize the graphite powder. For example, the above substances can be added to the graphite powder in batches.

[0060] After the oxidation of the graphite powder was completed, 570 ml of deionized water and 16 ml of hydrogen peroxide were added to terminate the oxidation reaction of the graphite powder.

[0061] The oxidized graphite powder is washed and filtered to obtain pure graphite oxide powder. The pure graphite oxide powder is mixed with a predetermined amount of deionized water to obtain a first mixed solution with a mass concentration of 2 mg / L. The first mixed solution is ultrasonicated by an ultrasonic machine to peel the graphite oxide powder into graphene oxide nanosheets and evenly disperse them in the first mixed solution.

[0062] A 0.18 mg / mL graphite carbon nitride aqueous dispersion was prepared, and the 0.18 mg / mL graphite carbon nitride aqueous dispersion was mixed with the first mixed solution in different proportions to obtain a second mixed solution with a mass proportion of 0%, 1.8%, 3.5%, 5.1%, 6.7%, and 8.3% of the graphite carbon nitride dispersion, respectively. The second mixed solution was ultrasonicated for 30 minutes using an ultrasonic machine to fully mix the graphene oxide nanosheets and the graphite carbon nitride nanosheets in the second mixed solution.

[0063] A second mixed liquid having a mass percentage of 0% of the graphite phase carbon nitride dispersion is placed in a filter cup, an anodized aluminum membrane is selected as a filter membrane, the second mixed liquid is vacuum filtered, and a graphene oxide membrane is deposited on the anodized aluminum membrane.

[0064] The anodized aluminum film on which the graphene oxide film was deposited was removed and dried at room temperature for 12 hours. After drying, the graphene oxide film was separated from the anodized aluminum film to obtain a graphene oxide film with a graphite phase carbon nitride content of 0%.

[0065] The second mixed liquids with the mass proportions of graphite phase carbon nitride dispersions being 1.8%, 3.5%, 5.1%, 6.7% and 8.3% were placed in the filter cup in sequence, and the above steps were repeated to vacuum filter and dry the second mixed liquid to obtain graphene oxide films with graphite phase carbon nitride contents of 1.8%, 3.5%, 5.1%, 6.7% and 8.3%.

[0066] The morphology and structure of the graphene oxide membrane prepared by the method of the present application and the hydrogen isotope water separation performance are described below.

[0067] The cross section of the prepared graphene oxide film was examined by scanning electron microscopy, and the following Figure 2 Scanning electron microscopy morphology shown. Figure 2 FIG. 1 is a scanning electron microscope morphology image of a cross section of a graphene oxide film according to an embodiment of the present application. Figure 2 As shown, the graphene oxide film prepared by the method for preparing a graphene oxide film provided in the present application has a complete layered structure in cross section.

[0068] The prepared graphene oxide film was tested by X-ray diffraction, and the following Figure 3 X-ray diffraction spectrum of graphene oxide film shown. Figure 3 : is an X-ray diffraction spectrum of a graphene oxide film according to an embodiment of the present application. The horizontal axis is the diffraction angle 2θ (degree), and the vertical axis is the diffraction intensity. Figure 3 As shown in Figure 1, when the diffraction angle 2θ = 11.24°, the diffraction intensity of the graphene oxide film reaches a peak value. According to the diffraction angle 2θ corresponding to the diffraction peak of the graphene oxide film and the Bragg equation, the interlayer distance of the graphene oxide film is determined to be The interlayer distance of graphene oxide film is larger than that of undoped graphite carbon nitride material It shows that the doped graphite phase carbon nitride material expands the interlayer spacing of the graphene oxide membrane, thereby increasing the rate at which water molecules pass through the capillary structure, further increasing the diffusion rate of water in the membrane and the permeation rate of water through the membrane.

[0069] The prepared graphene oxide film and the graphene oxide film of undoped graphite phase carbon nitride material were detected by X-ray photoelectron spectroscopy, and the following Figure 4 The X-ray photoelectron spectroscopy of graphene oxide film shown in FIG. Figure 5 The X-ray photoelectron spectroscopy spectrum of the graphene oxide film of the undoped graphite phase carbon nitride material is shown. Figure 4 This is an X-ray photoelectron spectroscopy spectrum of a graphene oxide film according to an embodiment of the present application. Figure 5This is the X-ray photoelectron spectrum of the graphene oxide film of undoped graphite phase carbon nitride material. The horizontal axis is the binding energy (eV) and the vertical axis is the relative intensity of the photoelectron. Figure 4 and Figure 5 As shown, the positions of the fitting peaks 30 of the carbon-nitrogen bond and the hydroxyl group, the carboxyl peak 10, and the carbonyl peak 20 in the X-ray photoelectron spectrum of the graphene oxide film are almost coincident. Moreover, when the binding energy is 286.17 eV, the fitting peak 30 of the carbon-nitrogen bond and the hydroxyl group in the X-ray photoelectron spectrum of the graphene oxide film is significantly higher than the hydroxyl peak 60 in the X-ray photoelectron spectrum of the graphene oxide film without the graphene phase carbon nitride material, indicating that a certain amount of carbon-nitrogen bonds exist in the graphene oxide film prepared by the method of the present application, thereby proving that the graphene phase carbon nitride material is successfully inserted into the graphene oxide film. At the same time, the sp 2 Hybridized carbon peak 50 and sp 3 The area ratio of the hybridized carbon peak 40 is 45.6%, while the X-ray photoelectron spectroscopy of the graphene oxide film without graphite phase carbon nitride material is sp 2 Hybridized carbon peak 50 and sp 3 The area ratio of the hybridized carbon peak 40 is 53%, further proving that the graphite phase carbon nitride material is successfully inserted into the graphene oxide film.

[0070] The hydrogen isotope water separation performance of the prepared graphene oxide membranes with different doping amounts was tested, and the following results were obtained: Figure 6 The relationship between the separation factor, permeation rate and doping amount of the graphene oxide membrane shown. Figure 6 : This is a graph showing the relationship between the separation factor, permeation rate and doping amount of a graphene oxide membrane according to an embodiment of the present application. The horizontal axis is the mass of graphite phase carbon nitride (mg), and the vertical axis is the separation factor and permeation rate (g·min -1 cm -2 ). By observing the relationship between the separation factor, permeation rate and doping amount of the graphene oxide membrane, it is found that the permeation rate of the composite membrane increases with the increase of the graphite phase carbon nitride doping amount, and maintains a high separation factor when the graphite phase carbon nitride doping amount is high. When the graphite phase carbon nitride doping amount is 6.7%, the permeation rate reaches a peak value of 7.2×10 -5 g·min -1 cm -2 , the separation factor reaches 1.1.

[0071] According to the scanning electron microscope morphology of the cross-section of the above-mentioned graphene oxide film, the X-ray diffraction spectrum of the graphene oxide film, the X-ray photoelectron energy spectrum spectrum, and the relationship diagram between the separation factor, permeation rate and doping amount, it is determined that the graphene oxide film prepared by the method for preparing a graphene oxide film provided in the present application has a complete layered structure and a higher diffusion rate and permeation rate. At the same time, the graphite phase carbon nitride material can be successfully inserted into the graphene oxide film, so that the graphene oxide film exhibits good hydrogen isotope water separation performance in the hydrogen isotope water separation performance test experiment.

[0072] Regarding the embodiments of the present application, it should also be noted that, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other to obtain new embodiments.

[0073] The above are only specific implementation methods of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a graphene oxide film, characterized in that: It includes the following steps: S10: obtaining graphite powder and deionized water; S20: oxidizing the graphite powder obtained in step S10; S30: mixing the oxidized graphite powder and the deionized water obtained in step S10 to obtain a first mixed solution; S40: obtaining a graphite phase carbon nitride dispersion; S50: mixing the first mixed solution obtained in step S30 with the graphite phase carbon nitride dispersion obtained in step S40 to obtain a second mixed solution; S60: depositing the second mixed solution on a filter membrane; S70: drying the filter membrane on which the second mixed solution is deposited; S80: Separating and obtaining the graphene oxide membrane from the filtration membrane.

2. The method according to claim 1, characterized in that In step S50, the mass concentration of the first mixed liquid is 1.5-2.5 mg / ml, and the mass concentration of the graphite phase carbon nitride dispersion is 0.1-0.2 mg / ml.

3. The method according to claim 1, characterized in that In step S50, the mass proportion of graphite-phase carbon nitride in the second mixed liquid is 1.8% to 8.3%.

4. The method according to claim 1, characterized in that: In step S50, the second mixed liquid is further subjected to ultrasonic treatment using an ultrasonic machine to mix the second mixed liquid uniformly.

5. The method according to claim 1, characterized in that In step S60, the second mixed solution is deposited on a filter membrane by vacuum filtration.

6. The method according to claim 1, characterized in that In step S70, the drying is performed at room temperature.

7. The method according to claim 1, characterized in that In step S70, the drying time is 10-12 hours.

8. The method according to claim 1, characterized in that In step S20, after the reaction is completed, deionized water and peroxide are added to the reactants to terminate the reaction.

9. The method according to claim 1, characterized in that: In step S20, a predetermined amount of concentrated sulfuric acid, a predetermined amount of potassium permanganate, a predetermined amount of sodium nitrate and a predetermined amount of deionized water are used to oxidize the graphite powder.

10. The method according to any one of claims 1 to 9, characterized in that: The filter membrane is aluminum oxide.

11. A graphene oxide film, characterized in that: The graphene oxide film is prepared by the method according to any one of claims 1 to 10.

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