Graphene oxide film as well as preparation method and application thereof

Abstract

The invention relates to a graphene oxide film as well as a preparation method and application thereof. For the pGO membrane, in a Fourier transform infrared spectrogram of the surface of the pGO membrane, a vibration peak exists in a wave band of 1840-1860 cm <-1 >; the ratio of the number of carbon atoms on the surface to the number of oxygen atoms on the surface is (1-1.5): 1; the preparation method comprises the following steps: treating the mGO membrane by using O2 plasma. The surface of the fGO membrane comprises the following groups: a semi-ionic C-F bond or a covalent C-F bond, the ratio of the number of fluorine atoms on the surface to the number of oxygen atoms on the surface is (0.19-0.30): 1, and the preparation method of the fGO membrane comprises the following steps: carrying out fluorination treatment on the mGO membrane by using XeF2. The graphene oxide membrane can selectively permeate water or an organic solvent in a water-organic solvent steam system, and the separation flux of the water or the organic solvent can be improved.

Description

Technical Field

[0001] This invention relates to a graphene oxide film, its preparation method, and its applications. Background Technology

[0002] Membrane separation, used for the dehydration and purification of chemicals, known as pervaporation and vapor permeation, has been extensively studied as a viable alternative to traditional distillation methods. Graphene oxide (GO), as a graphene intermediate, unlike its precursor graphite, is synthesized through a strong oxidation process, allowing it to be readily separated as a monolayer in aqueous solution. This makes it possible to significantly expand the applications of graphene oxide (GO) in many fields.

[0003] Graphene oxide sheets have been used to prepare strong, tough paper-like materials, membranes, thin films, and composites through methods such as filtration, coating, and solution chemistry. Thin films or Buckpaper, formed by stacking graphene oxide sheets layer by layer, exhibit some unique properties. Graphene oxide films possess both mechanical strength and flexibility at thicknesses in the nanometer or micrometer range. This is why graphene oxide films have recently been used as separation membranes.

[0004] Membrane-based selective separation processes for liquid or vapor mixtures, known as pervaporation, have attracted widespread attention in the production of high-purity chemicals in many fields, such as pharmaceuticals and biotechnology. As a single-stage process, pervaporation is particularly effective for separating azeotropic mixtures. Azeotropic mixtures consist of two or more liquids in proportions that cannot be altered by distillation and are difficult to separate using conventional distillation methods. Pervaporation requires the membrane to be selective for one component of the mixture (water or an organic solvent).

[0005] Recently, graphene oxide membranes for pervaporation processes in solvent and alcohol dehydration and purification have been reported and extensively studied as a viable alternative to traditional pervaporation membranes. Based on the phase state of the feedstock, pervaporation (PV) uses mixed solutions as feedstocks, while vapor permeation (VP) uses mixed vapors. Most research on the use of graphene oxide membranes for organic solvent dehydration has focused on PV, which can separate binary or multi-component liquid mixtures. Although vapor permeation (VP) has the advantage of no phase change during the permeation process from the feedstock to the permeate side, thus avoiding the problem of heat of vaporization supply, and the concentration polarization on the feedstock side of the membrane is less significant than in pervaporation (PV).

[0006] Both pervaporation and vapor permeation are membrane-based processes that selectively separate liquid or vapor mixtures through partial vaporization using a non-porous or porous membrane that acts as a selective barrier between the feed and the permeate. It can effectively dilute solutions containing trace or small amounts of the component to be removed. It is clear that membranes are also a key component in vapor permeation, but existing polymer and inorganic membranes still perform poorly in terms of permeability and selectivity. Summary of the Invention

[0007] To overcome the shortcomings of existing polymer and inorganic membranes in terms of poor permeability and selectivity during vapor permeation, this invention provides a graphene oxide membrane, its preparation method, and its applications. The graphene oxide membrane of this invention can selectively permeate water or organic solvents in a water-organic solvent vapor system, thereby improving the separation flux of water or organic solvents.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a graphene oxide film (pGO film), the Fourier transform infrared spectrum of which shows a peak value in the 1840-1860 cm⁻¹ region. -1 The band exhibits vibrational peaks; the ratio of the number of carbon atoms on its surface to the number of oxygen atoms on its surface is (1-1.5):1.

[0010] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is in the range of 850-890 cm⁻¹. -1 Vibrational peaks may be present in the band. These vibrational peaks are preferably those of the -C-OH group.

[0011] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is located in the 1240-1270 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably vibrational peaks of the -COC bond.

[0012] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is located in the 1410-1430 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably those of the -COOH group.

[0013] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is in the range of 1600-1630 cm⁻¹. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably those of the -COOH group.

[0014] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is located in the 1720-1750 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably C=O bond vibrational peaks.

[0015] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is located in the 1840-1860 cm⁻¹ range. -1 The band may contain vibrational peaks of C=O bonds.

[0016] In certain specific embodiments of the present invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (pGO film) is as follows: Figure 2 As shown.

[0017] In this invention, the ratio of the number of carbon atoms on the surface of the graphene oxide film to the number of oxygen atoms on the surface of the graphene oxide film is preferably 1.25:1;

[0018] In this invention, the oxygen atom content on the surface of the graphene oxide film (pGO film) can be 40%-50%, for example 44.4%, and the percentage is the percentage of the number of oxygen atoms on the surface of the graphene oxide film (pGO film) to the sum of the number of oxygen atoms and carbon atoms on the surface of the graphene oxide film (pGO film).

[0019] In this invention, the carbon atom content on the surface of the graphene oxide film (pGO film) can be 50%-60%, for example 55.6%, where the percentage is the percentage of the number of carbon atoms on the surface of the graphene oxide film (pGO film) to the sum of the number of oxygen atoms and carbon atoms on the surface of the graphene oxide film (pGO film).

[0020] In certain specific embodiments of the present invention, the energy dispersive spectroscopy of the surface of the graphene oxide film (pGO film) is as follows: Figure 5 As shown.

[0021] In this invention, the thickness of the graphene oxide film (pGO film) can be 0.3-0.4 μm, for example 0.33 μm.

[0022] In this invention, the interlayer distance between the graphene oxide films (pGO films) in a dry environment can be [missing information]. For example

[0023] In this invention, the interlayer distance between the graphene oxide films (pGO films) in water vapor can be [missing information]. For example,

[0024] In this invention, the interlayer distance between the graphene oxide films (pGO films) in ethanol vapor can be [missing information]. For example,

[0025] In this invention, the interlayer distance between the graphene oxide films (pGO films) in a mixed vapor of water and methanol at a weight ratio of 1:1 can be [missing information]. For example,

[0026] In this invention, the interlayer distance between the graphene oxide films (pGO films) in a mixed vapor of water and ethanol at a weight ratio of 1:1 can be [missing information]. For example,

[0027] In this invention, the interlayer distance between the graphene oxide films (pGO films) in a mixed vapor of water and isopropanol at a weight ratio of 1:1 can be [missing information]. For example,

[0028] In this invention, the interlayer distance between the graphene oxide films (pGO films) in a mixed vapor of water and n-butanol at a weight ratio of 1:1 can be [missing information]. For example,

[0029] Secondly, the present invention provides a method for preparing a graphene oxide membrane (pGO membrane), which includes the following steps: treating the mGO membrane with O2 plasma.

[0030] In this invention, the plasma O2 flow rate is determined by the complete treatment process, and the ratio of the plasma O2 flow rate to the surface area of ​​the mGO membrane is not less than 20 sccm / in. 2 Preferably, the plasma O2 flux is 60 sccm. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0031] In this invention, the mGO membrane is an existing product. It can be a circular sheet with a diameter of 37-39 mm and a surface area of ​​1.67 in. 2 (1100mm 2 The thickness can be 0.33 μm, measured by a surface profilometer. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0032] In this invention, the method for preparing the mGO membrane is a conventional method and may include the following steps: dispersing mGO in water by ultrasonication to form an mGO dispersion, filtering the mGO dispersion by vacuum, and drying it on a filter membrane support layer to obtain an mGO membrane.

[0033] The vacuum-filtered mGO dispersion can be 20 mL. The concentration can be 0.1 mg / mL. Drying can be performed overnight in a nitrogen chamber. mGO is preferably prepared by the following method: dispersing graphite powder in concentrated sulfuric acid; then cooling the dispersion to 10°C; subsequently, adding potassium permanganate and stirring at no more than 30°C for no more than 3 hours; then pouring the reaction mixture onto ice and adding hydrogen peroxide dropwise until the gas is completely released, and obtaining mGO by filtration. The weight ratio of graphite powder to potassium permanganate is preferably 1:3. The concentration of hydrogen peroxide is preferably 30 wt%. The preferred ratio of graphite powder, concentrated sulfuric acid, and hydrogen peroxide is 1 kg: 30 L: 0.3 L.

[0034] In this invention, the equipment used for the processing is conventional in the art, such as an etching machine. The microwave power of the etching machine is determined by the completeness of the processing, and the ratio of the microwave power of the etching machine to the surface area of ​​the mGO film is not less than 20 W / in. 2 Preferably, the microwave power of the etching machine is 60W. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0035] In this invention, the vacuum level of the processing environment can be 0.1-1 torr.

[0036] In this invention, the processing time is determined by the completeness of the process, and the ratio of the processing time to the surface area of ​​the mGO membrane is not less than 60 s / in. 2 Preferably, the processing time is 180 seconds. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0037] Thirdly, the present invention provides a graphene oxide film (pGO film), which is prepared according to the preparation method of graphene oxide film (pGO film) as described above.

[0038] Fourthly, the present invention provides a graphene oxide film (fGO film) whose surface includes the following groups: half-ionic CF bonds or covalent CF bonds, and the ratio of the number of fluorine atoms on its surface to the number of oxygen atoms on its surface is (0.19-0.30):1.

[0039] In this invention, the surface of the graphene oxide film may include the following groups: semi-ionic CF bonds and covalent CF bonds.

[0040] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) is located in the 850-890 cm⁻¹ range. -1 Vibrational peaks may be present in the band. These vibrational peaks are preferably those of the -C-OH group.

[0041] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) is in the range of 1035-1050 cm⁻¹. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably located in the CF band. x The vibrational peaks of the functional group, where x>1.

[0042] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) is located in the 1160-1190 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably those of the CF bond in the half-ion.

[0043] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) is located in the 1260-1290 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably those of covalent CF bonds.

[0044] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) is located in the 1720-1760 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably C=O bond vibrational peaks.

[0045] In this invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) is located in the 1850-1890 cm⁻¹ range. -1 Vibrational peaks may exist in the band. These vibrational peaks are preferably those of the FC=O group.

[0046] In certain specific embodiments of the present invention, the Fourier transform infrared spectrum of the surface of the graphene oxide film (fGO film) can be as follows: Figure 3 As shown.

[0047] In this invention, the ratio of the number of fluorine atoms on the surface of the graphene oxide film (fGO film) to the number of oxygen atoms on its surface is preferably 0.289:1.

[0048] In this invention, the ratio of the number of carbon atoms on the surface of the graphene oxide film (fGO film) to the number of oxygen atoms on its surface can be (6-8):1, for example 7.17:1.

[0049] In this invention, the oxygen atom content on the surface of the graphene oxide film (fGO film) can be less than 10%, preferably 7%-9.5%, for example 8.6%, and the percentage is the percentage of the number of oxygen atoms on the surface of the graphene oxide film to the sum of the number of oxygen atoms, fluorine atoms and carbon atoms on the surface of the graphene oxide film.

[0050] In this invention, the fluorine atom content on the surface of the graphene oxide film (fGO film) can be 20%-40%, preferably 28%-36%, for example 29.75%, and the percentage is the percentage of the number of fluorine atoms on the surface of the graphene oxide film (fGO film) to the sum of the number of oxygen atoms, fluorine atoms and carbon atoms on the surface of the graphene oxide film (fGO film).

[0051] In this invention, the carbon atom content on the surface of the graphene oxide film (fGO film) can be 61.65%, which is the percentage of the number of carbon atoms on the surface of the graphene oxide film (fGO film) to the sum of the number of oxygen atoms, fluorine atoms and carbon atoms on the surface of the graphene oxide film (fGO film).

[0052] In certain specific embodiments of the present invention, the energy dispersive spectrum of the elemental analysis of the surface of the graphene oxide film (fGO film) can be as follows: Figure 6 As shown.

[0053] In this invention, the thickness of the graphene oxide film (fGO film) can be 0.3-0.4 μm, for example 0.33 μm.

[0054] In this invention, the interlayer distance between the graphene oxide films (fGO films) in a dry environment can be [missing information]. For example

[0055] In this invention, the interlayer distance between the graphene oxide films (fGO films) in water vapor can be [missing information]. For example,

[0056] In this invention, the interlayer distance between the graphene oxide films (fGO films) in ethanol vapor can be [missing information]. For example,

[0057] In this invention, the interlayer distance between the graphene oxide films (fGO films) in a mixed vapor of water and methanol at a weight ratio of 1:1 can be [missing information]. For example,

[0058] In this invention, the interlayer distance between the graphene oxide films (fGO films) in a mixed vapor of water and ethanol at a weight ratio of 1:1 can be [missing information]. For example,

[0059] In this invention, the interlayer distance between the graphene oxide films (fGO films) in a mixed vapor of water and isopropanol at a weight ratio of 1:1 can be [missing information]. For example,

[0060] In this invention, the interlayer distance between the graphene oxide films (fGO films) in a mixed vapor of water and n-butanol at a weight ratio of 1:1 can be [missing information]. For example,

[0061] Fifthly, the present invention provides a method for preparing a graphene oxide membrane (fGO membrane), which includes the following steps: fluorinating the mGO membrane with XeF2.

[0062] In this invention, the mGO membrane is an existing product. It can be a circular sheet with a diameter of 37-39 mm and a surface area of ​​1.67 in. 2 (1100mm 2 The thickness can be 0.33 μm, measured by a surface profilometer. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0063] In this invention, the method for preparing the mGO membrane is a conventional method and may include the following steps: dispersing mGO in water by ultrasonication to form an mGO dispersion, filtering the mGO dispersion by vacuum, and drying it on a filter membrane support layer to obtain an mGO membrane.

[0064] The vacuum-filtered mGO dispersion can be 20 mL. The concentration can be 0.1 mg / mL. Drying can be performed overnight in a nitrogen chamber. mGO is preferably prepared by the following method: dispersing graphite powder in concentrated sulfuric acid; then cooling the dispersion to 10°C; subsequently, adding potassium permanganate and stirring at no more than 30°C for no more than 3 hours; then pouring the reaction mixture onto ice and adding hydrogen peroxide dropwise until the gas is completely released, and obtaining mGO by filtration. The weight ratio of graphite powder to potassium permanganate is preferably 1:3. The concentration of hydrogen peroxide is preferably 30 wt%. The preferred ratio of graphite powder, concentrated sulfuric acid, and hydrogen peroxide is 1 kg: 30 L: 0.3 L.

[0065] In this invention, the fluorination process can be as follows: first, the mGO membrane is reacted with XeF2, then rinsed, completing a pulse reaction cycle. The fluorination process completes at least two pulse reaction cycles. The reaction time is determined by the completeness of the reaction, and the ratio of the reaction time to the surface area of ​​the mGO membrane is not less than 15 s / in. 2 Preferably, the reaction time is 30 seconds. The rinsing can be performed using nitrogen or an inert gas. The fluorination treatment can be completed in 10 pulse reaction cycles. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0066] In this invention, the temperature of the fluorination treatment is conventional in the art, for example, 0-40°C.

[0067] In this invention, during the fluorination treatment, the pressure of the XeF2 can be no less than 3000 mTorr.

[0068] In a sixth aspect, the present invention provides a graphene oxide film (fGO film) prepared according to the preparation method of graphene oxide film (fGO film) as described above.

[0069] In a seventh aspect, the present invention provides an application of graphene oxide membrane in vapor permeation of a water-organic solvent system.

[0070] In this invention, the graphene oxide film may be an nGO film, an mGO film, a graphene oxide film (pGO film) as described in the first to third aspects, or a graphene oxide film (fGO film) as described in the fourth to sixth aspects.

[0071] The nGO membrane is an existing product, and its preparation method is a conventional method, which may include the following steps: dispersing nGO in water by ultrasound to form an nGO dispersion, then filtering the nGO dispersion under vacuum while drying it on a filter support layer to obtain the nGO membrane. The vacuum-filtered nGO dispersion can be 20 mL. The concentration can be 0.1 mg / mL. Drying can be done overnight in a nitrogen chamber. The preparation method of nGO may include the following steps: first, cooling concentrated sulfuric acid in an ice bath, then adding flake graphite and potassium permanganate, controlling the reaction temperature at about 5°C, and stirring the reaction; next, transferring the reaction mixture to a heat-collecting constant-temperature stirrer, and continuing to stir the reaction at 35°C; then, adding deionized water and raising the temperature to 95°C, and continuing to stir; finally, adding hydrogen peroxide and stirring the reaction at room temperature to obtain nGO.

[0072] The mGO membrane is an existing product. It can be a circular sheet with a diameter of 37-39 mm and a surface area of ​​1.67 in. 2 (1100mm 2 The thickness can be 0.33 μm, measured by a surface profilometer. The "surface area" refers to the area of ​​one side of the graphene oxide film.

[0073] The method for preparing the mGO membrane is a conventional method and may include the following steps: dispersing mGO in water by ultrasonication to form an mGO dispersion, filtering the mGO dispersion by vacuum, and drying it on a filter membrane support layer to obtain the mGO membrane.

[0074] The vacuum-filtered mGO dispersion can be 20 mL in volume. The concentration can be 0.1 mg / mL. Drying can be performed overnight in a nitrogen chamber. mGO can be prepared by the following method: dispersing graphite powder in concentrated sulfuric acid. Then cooling the dispersion. Subsequently, slowly adding potassium permanganate to achieve a graphite powder to potassium permanganate weight ratio of 1:3, and stirring. Then pouring the reaction mixture onto ice and adding hydrogen peroxide dropwise until the gas is completely released, and obtaining mGO by filtration.

[0075] In this invention, the organic solvent may be one or more of alcohol solvents, ester solvents, ketone solvents, and amide solvents.

[0076] The alcohol solvent is a conventional choice in the art, such as one or more of methanol, ethanol, isopropanol and n-butanol.

[0077] The ester solvent is a conventional choice in the art, such as one or more of ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0078] The ketone solvent is a conventional choice in the art, such as methylpyrrolidone.

[0079] The amide solvent is a conventional choice in the art, such as dimethylacetamide.

[0080] In some specific embodiments of the present invention, the water-organic solvent system is a water-methanol binary system, a water-isopropanol binary system, a water-n-butanol binary system, or a water-ethanol binary system.

[0081] In this invention, the mass ratio of water to organic solvent can be 1:1 to 2:8.

[0082] In this invention, the temperature of the vapor permeation can be 0-75℃, for example 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃ or 75℃.

[0083] In this invention, the pressure of the vapor permeation may not be higher than atmospheric pressure, for example, atmospheric pressure.

[0084] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0085] The reagents and raw materials used in this invention are all commercially available.

[0086] The positive and progressive effects of this invention are as follows:

[0087] (1) The pGO membrane of the present invention has an increased surface oxygen content, which leads to an increase in water vapor flux and separation coefficient;

[0088] (2) This invention employs oxygen (O2) plasma dry peroxidation to treat the surface of graphene oxide membrane to obtain a pGO membrane, which gives it greater water vapor permeability. O2 plasma increases the surface oxygen content of the graphene oxide membrane, thereby enhancing its interlayer distance in water vapor, leading to an increase in water vapor flux and separation coefficient;

[0089] (3) The fGO membrane of the present invention undergoes fluorination on its surface due to the reaction between fluorine atoms and carbon atoms in the honeycomb lattice of graphene oxide, resulting in higher flux and separation selectivity of organic solvent vapor.

[0090] (4) This invention employs xenon difluoride (XeF2) gas to perform dry fluorination treatment on the surface of graphene oxide membranes to obtain fGO membranes. After XeF2 treatment, fluorine functional groups and a small amount of existing oxygen functional groups coexist on the surface of the graphene oxide membrane. Therefore, organic solvent vapors can more easily permeate the graphene oxide membrane, and the fGO membrane has higher flux and separation selectivity for organic solvent vapors;

[0091] (5) In this invention, the interlayer distance between graphene oxides in the pGO film can be increased to greater than [amount missing]. In water vapor, the interlayer distance between fGO films and graphene oxides can be reduced to less than [value missing].

[0092] (6) In this invention, graphene oxide membranes are proposed for use in steam permeation separation of water or organic solvents in water-organic solvent systems. Attached Figure Description

[0093] Figure 1 Fourier transform infrared spectrum of the surface of the mGO film prepared from the raw material in Example 1;

[0094] Figure 2 The Fourier transform infrared spectrum of the surface of the pGO film in Example 1;

[0095] Figure 3 The Fourier transform infrared spectrum of the surface of the fGO film in Example 2;

[0096] Figure 4 Energy dispersive spectroscopy of the surface of the mGO film prepared from the raw materials in Example 1;

[0097] Figure 5 The energy dispersive spectrum of the surface of the pGO film in Example 1 is shown in the image.

[0098] Figure 6 The energy dispersive spectrum of the surface of the fGO film in Example 2 is shown in the image.

[0099] Figure 7 The image shows the leakage test results of the micro-permeable vaporization chamber in Example 2.

[0100] Figure 8 The calibration data graph for the water vapor permeation test in Example 2 is shown.

[0101] Figure 9 The calibration data graph for the ethanol vapor permeation test in Example 2 is shown.

[0102] Figure 10 The image shows the result of water vapor passing through the graphene oxide membrane in Example 2.

[0103] Figure 11 The image shows the result of ethanol vapor passing through the graphene oxide membrane in Example 2.

[0104] Figure 12 The graph shows the interlayer distance data of the graphene oxide film in Example 3 measured by XRD in a dry environment;

[0105] Figure 13 The graph shows the interlayer distance data of the graphene oxide film in Example 3 measured by XRD in a water vapor environment;

[0106] Figure 14 The graph shows the interlayer distance data of the graphene oxide film in Example 3 measured by XRD in an ethanol vapor environment;

[0107] Figure 15 The flux results of the graphene oxide membrane in the water-ethanol binary vapor system in Example 4 are shown in the figure.

[0108] Figure 16 The separation coefficient results of the graphene oxide membrane in the water-ethanol binary vapor system in Example 4 are shown in the figure.

[0109] Figure 17 The graph shows the water flux results of the graphene oxide membrane in the water-ethanol binary vapor system in Example 4.

[0110] Figure 18 The graph shows the ethanol flux results of the graphene oxide membrane in the water-ethanol binary vapor system in Example 4.

[0111] Figure 19 The graph in Example 5 shows the relationship between the separation coefficient and flux of various membranes in the water-ethanol binary vapor system.

[0112] Figure 20 The graph shows the interlayer distance data of the graphene oxide film in Example 6 measured by XRD in a mixed vapor environment of water and methanol.

[0113] Figure 21The graph shows the interlayer distance data of the graphene oxide film in Example 6 measured by XRD in a mixed vapor environment of water and ethanol.

[0114] Figure 22 The graph shows the interlayer distance data of the graphene oxide film in Example 6 measured by XRD in a mixed vapor environment of water and isopropanol.

[0115] Figure 23 The graph shows the interlayer distance data of the graphene oxide film in Example 6 measured by XRD in a mixed vapor environment of water and n-butanol.

[0116] Figure 24 The graph shows the flux results of the pGO membrane in various water-alcohol binary vapor systems in Example 7.

[0117] Figure 25 The graph shows the separation coefficient results of the pGO membrane in various water-alcohol binary vapor systems in Example 7.

[0118] Figure 26 The graph shows the flux results of the fGO membrane in various water-alcohol binary vapor systems in Example 7.

[0119] Figure 27 The graph shows the separation coefficient results of the fGO membrane in various water-alcohol binary vapor systems in Example 7.

[0120] Figure 28 The graph in Example 8 shows the relationship between interlayer distance and flux of the pGO membrane in various water-alcohol binary vapor systems.

[0121] Figure 29 The graph in Example 8 shows the relationship between the interlayer distance and the separation coefficient of the pGO membrane in various water-alcohol binary vapor systems.

[0122] Figure 30 The graph in Example 8 shows the relationship between interlayer distance and flux of the fGO membrane in various water-alcohol binary vapor systems.

[0123] Figure 31 The graph in Example 8 shows the relationship between the interlayer distance and the separation coefficient of the fGO membrane in various water-alcohol binary vapor systems. Detailed Implementation

[0124] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0125] The separation factor (SF) is the ratio of the fractions of water vapor i to organic solvent vapor j in the vapor permeation of the water-organic solvent system, divided by the ratio of the fractions of water vapor i to organic solvent vapor j in the feed stream, as follows:

[0126]

[0127] Where, x i,p and x j,p It is the fraction of components i and j in the permeate gas, x i,f and x j,f It represents the fractions of components i and j in the feed gas.

[0128] Flux refers to the sum of the flow rates of water vapor and organic solvent vapor during the vapor permeation of the water-organic solvent system.

[0129] Water flux refers to the flow rate of water vapor permeating during the vapor permeation of the water-organic solvent system.

[0130] Organic solvent (e.g., ethanol) flux refers to the flow rate of organic solvent vapor (e.g., ethanol vapor) permeating during the vapor permeation of the water-organic solvent system.

[0131] Example 1: Preparation of mGO membrane

[0132] mGO was prepared by the following method: Based on a modified Hummer's process, 1 kg of graphite powder (flake graphite or artificial graphite with a purity of ≥90%, 100 mesh) was dispersed in 30 L of concentrated sulfuric acid. The dispersion was then cooled to approximately 10°C. Subsequently, 3 kg of potassium permanganate was slowly added to achieve a graphite powder to potassium permanganate weight ratio of 1:3, and the mixture was stirred for no more than 3 hours at a temperature not exceeding 30°C. The reaction mixture was then poured onto 60 kg of ice, and 0.3 L of hydrogen peroxide (30 wt%) was added dropwise until the gas was completely released. The resulting mGO was obtained by filtration.

[0133] The mGO membrane was prepared by the following method: mGO was dispersed in water by ultrasonication to form an mGO dispersion, which was then filtered under vacuum and dried on an anodized aluminum oxide (AAO) filter support layer (Whatman, 47 mm in diameter, 0.2 μm in pore size) to obtain the mGO membrane; wherein, the vacuum-filtered mGO dispersion was 20 mL with a concentration of 0.1 mg / mL; and drying was carried out overnight in a nitrogen chamber.

[0134] The resulting mGO film was a circular disc with a diameter of 37-39 mm and a surface area of ​​approximately 1.67 in. 2 (1100mm 2 The thickness is approximately 0.33 μm, as measured by a surface profilometer.

[0135] Example 2: Preparation of rGO membranes

[0136] rGO is prepared by the following method: mGO from the raw material preparation example 1 is treated at high temperature under an inert gas or reduced by immersion in a reducing agent solution (such as hydrazine) to remove oxygen-containing functional groups.

[0137] The rGO membrane was prepared by the following method: rGO was dispersed in water by ultrasonication to form an rGO dispersion, which was then filtered under vacuum while being dried on an anodic alumina (AAO) filter membrane support layer (Whatman, 47 mm in diameter, 0.2 μm in pore size) to obtain the rGO membrane; wherein, the vacuum-filtered rGO dispersion was 20 mL with a concentration of 0.1 mg / mL; and drying was carried out overnight in a nitrogen chamber.

[0138] Example 3: Preparation of nGO membranes

[0139] nGO was prepared by the following method: Based on Hummer's process, 1 kg of graphite powder (flake graphite or artificial graphite with a purity of ≥90%) was dispersed in 60 L of concentrated sulfuric acid. The dispersion was then cooled to approximately 10°C. Subsequently, 6 kg of potassium permanganate was slowly added to achieve a graphite powder to potassium permanganate weight ratio of 1:6, and the mixture was heated to 40-50°C and stirred for at least 4 hours. The reaction mixture was then poured onto 60 kg of ice, and 0.6 L of hydrogen peroxide (30 wt%) was added dropwise until the gas was completely released. The nGO precursor was filtered off, and the mixture was washed with 120 L of 5 wt% hydrochloric acid by stirring. The resulting product, nGO, was obtained by filtration.

[0140] The nGO membrane was prepared by the following method: nGO was dispersed in water by ultrasonication to form an nGO dispersion, which was then filtered under vacuum while being dried on an anodic aluminum oxide (AAO) filter membrane support layer (Whatman, 47 mm in diameter, 0.2 μm in pore size) to obtain the nGO membrane; wherein, the vacuum-filtered nGO dispersion was 20 mL with a concentration of 0.1 mg / mL; and drying was carried out overnight in a nitrogen chamber.

[0141] Example 1: Graphene peroxide membrane (pGO membrane, plasma treated)

[0142] The surface of the mGO film in Raw Material Preparation Example 1 was modified using O2 plasma generated by a RIE etching machine (Plasma finish V15-G) to obtain a graphene peroxide film (pGO film).

[0143] The RIE etching machine was set to a microwave power of 60W, with a working pressure of approximately 0.1 Torr within the chamber. The oxygen flow rate during the process was set to 60 sccm, and the processing time was 180 seconds.

[0144] Example 2: Fluorinated graphene oxide membrane (fGO membrane, XeF2 treated)

[0145] The mGO membrane was fluorinated using XeF2 generated by a pulsed xenon difluoride (XeF2) reaction system to obtain a fluorinated graphene oxide membrane (fGO membrane).

[0146] The specific process is as follows: XeF2 is pulsed into the reaction chamber in the gas phase until the pressure in the chamber reaches 3000 mTorr. Then, the reaction of the mGO membrane in the raw material preparation example 1 with XeF2 is carried out for 30 seconds. Then, the reaction chamber is flushed with N2 to complete one pulse reaction cycle. The fGO membrane is synthesized at room temperature. After 10 pulse cycles, it is equivalent to 5 minutes of XeF2 treatment.

[0147] Example 1: Surface properties of graphene oxide film

[0148] 1. Test objects: mGO membrane prepared in Example 1, graphene peroxide membrane (pGO membrane) prepared in Example 1, and fluorinated graphene oxide membrane (fGO membrane) prepared in Example 2.

[0149] 2. Test Results:

[0150] (1) Fourier transform infrared spectroscopy

[0151] Figure 1-3 (Fourier transform infrared spectroscopy, using industry-standard testing methods) demonstrates the effects of mGO film surface modification before and after modification. Figure 1 The dashed line represents the primitive functional groups in the mGO. For example... Figure 2 The results show that many functional groups still exist on the surface after O2 plasma treatment. Figure 2 Approximately 1843cm -1 The dashed lines at the point represent newly formed C=O bonds after O2 plasma treatment.

[0152] Figure 3 CF x The dashed lines at the half-ionic CF, covalent CF, and FC=O locations represent fluorine functional groups generated after XeF2 treatment. For example... Figure 3 When the mGO membrane reacts with XeF2 gas, the FTIR spectrum of the resulting fGO membrane shows the coexistence of fluorine and native functional groups, namely, -COOH (approximately 1419 cm⁻¹). -1 Approximately 1606cm -1 ) and -C-OH are FC=O (approximately 1870cm) -1 ) and -CF (covalent: approx. 1274cm) -1 Half-ion: approximately 1176 cm⁻¹ -1) replaces, while C=O (approximately 1741cm) -1 Most remained unresponsive.

[0153] (2) Energy dispersive spectroscopy

[0154] like Figure 4-6 The increase in oxygen content was measured by energy dispersive spectroscopy (EDS, using a standardized testing method commonly used in the industry), reflecting the energy dispersive spectra of elemental analysis on the surfaces of mGO, pGO, and fGO films.

[0155] based on Figure 4-5 The results comparison showed that O2 plasma treatment resulted in the formation of more oxygen-containing functional groups. For example... Figure 6 The EDS spectrum showed that after fluorination, the mGO membrane had far more fluorine atoms than oxygen atoms on its surface, indicating that XeF2 gas treatment can effectively fluorinate the mGO membrane surface.

[0156] Example 2: Air permeability test of graphene oxide membrane

[0157] 1. Test objects: mGO membrane prepared in raw material preparation example 1, rGO membrane prepared in raw material preparation example 2, graphene peroxide membrane (pGO membrane) prepared in example 1, and fluorinated graphene oxide membrane (fGO membrane) prepared in example 2.

[0158] 2. Testing Method:

[0159] Thermogravimetric analysis (TGA) and mass spectrometry (MS) were used to perform vapor permeation tests on the graphene oxide membrane. The micro-pervaporization chamber (μ-pervap chamber) used for the vapor permeation experiment was made of stainless steel.

[0160] Before formal testing, a leak test was conducted on the micropervaporization chamber with a silicon wafer without a graphene oxide film. The procedure was as follows: A vapor source (a 1:1 weight ratio water-ethanol mixture) was loaded into the micropervaporization chamber. Then, a silicon wafer (3mm × 3mm) without openings or a graphene oxide film was loaded onto a 0.1μm thick Teflon film as a sealing gasket. Next, a stainless steel gasket with a 1.2mm diameter hole in the center was placed on the silicon wafer. Finally, a stainless steel cover was placed, and all components were tightly secured with screws. During the leak test, as the temperature increased, [the following occurred]. Figure 7 As shown, no mass loss or change in mass number (m / z) of water and ethanol was detected in the leak test. Therefore, it can be confirmed that the mass loss detected when the graphene oxide membrane is loaded comes only from the permeate passing through the graphene oxide membrane.

[0161] It should be noted that all vapor permeation experiments were conducted under a nitrogen atmosphere. Prior to the vapor permeation experiments, calibration was performed between thermogravimetric analysis (TGA) and mass spectrometry (MS) using a pinhole method. Mass spectrometry analysis data enabled the calibration to analyze the quantity of each component in the permeate. Specifically, pure liquids were placed in separate containers as vapor sources. During calibration, the evaporation rate of each component was controlled by limiting the evaporation area, and the calibration was performed without a graphene oxide membrane. For example, the calibration data for water and ethanol are shown below. Figure 8-9 As shown, the calibration data for water and ethanol were obtained within the ranges of room temperature to 95°C (water) and room temperature to 85°C (ethanol), respectively. Figure 8-9 The calibration data for water and ethanol between TGA and MS are presented. Figure 8 and Figure 9 The calibration between TGA and MS for pure water and pure ethanol is reflected separately. The mass numbers of water and ethanol (from MS) were measured based on the change in mass loss (i.e., the amount of evaporation in the TGA). When measuring the water-ethanol binary vapor, the content of water and ethanol in the permeate can be analyzed based on the respective MS data of pure water and ethanol.

[0162] To begin testing, a binary mixture solution (2:8 weight ratio of water to ethanol) is loaded into the micropervaporization chamber. Using a 0.1 μm thick Teflon film as a sealing gasket, a graphene oxide membrane (mGO, pGO, fGO, or rGO) is transferred onto a silicon wafer with an opening (60 μm × 60 μm) and then loaded onto the Teflon film gasket (an alternative is to omit the graphene oxide membrane). Next, a stainless steel gasket with a 1.2 mm diameter hole in the center is placed on the silicon wafer, and finally, a stainless steel cap is placed. All components are then securely locked in place using screws and bolts.

[0163] 3. Test Results:

[0164] Figure 10 and Figure 11 The results of water vapor and ethanol vapor passing through graphene oxide membranes (mGO, pGO, fGO, or rGO) are shown separately, with measurements performed at atmospheric pressure and 35°C. The pGO membrane showed the greatest mass loss of pure water, indicating its rapid water transport properties and making it easier for water vapor to pass through. A small amount of water was also detected passing through the fGO membrane. Furthermore, water vapor permeation measured by thermogravimetric analysis (e.g.) shows... Figure 10 No water permeates through the rGO membrane, which also means that there is no leakage in the micro-osmotic evaporation chamber.

[0165] Figure 11The permeation of ethanol vapor through GO membranes (mGO, pGO, fGO, or rGO membranes) is shown by thermogravimetric analysis. No ethanol vapor permeation was measured in mGO and pGO membranes, nor in rGO membranes. Ethanol vapor permeation was only measured in fluorinated graphene oxide (fGO) membranes, which, unlike rGO membranes, are only surface-fluorinated and therefore have interlayer spaces.

[0166] Example 3: Interlayer distance between graphene oxide layers in graphene oxide films under dry, water vapor, and ethanol vapor environments.

[0167] 1. Test objects: mGO membrane prepared in Example 1, graphene peroxide membrane (pGO membrane) prepared in Example 1, and fluorinated graphene oxide membrane (fGO membrane) prepared in Example 2.

[0168] 2. Test Results:

[0169] like Figure 12-14 As shown (XRD measurement, using industry-standardized testing methods), Figure 12 , Figure 13 and Figure 14 The values ​​reflect the interlayer distances of mGO, pGO, and fGO membranes as measured by XRD in dry, water vapor, and ethanol vapor environments, respectively.

[0170] like Figure 12 Based on the 2θ corresponding to the peak value in the figure, and using the Bragg equation 2dsinθ=nλ (λ=0.15406nm, n=1), the interlayer distances d of the mGO, pGO, and fGO films under dry conditions are calculated as follows: and Similarly, from Figure 13 As can be seen from the data, the interlayer distances d of the mGO, pGO, and fGO membranes under water vapor conditions are respectively... and from Figure 14 As can be seen from the data, the interlayer distances d of the mGO, pGO, and fGO membranes under ethanol vapor conditions are respectively... and

[0171] This shows that the interlayer distance of pGO and fGO did not change significantly in the dry state, proving that only the surface of the graphene oxide film was modified, and the dry treatment had no effect on the interior of the graphene oxide film. Therefore, the graphene oxide flakes inside the pGO and fGO films retained their original properties before drying. The interlayer distance of mGO and pGO films increased in a water vapor environment, but hardly increased in an ethanol vapor environment; while fGO films showed the opposite trend, with almost no increase in interlayer distance in a water vapor environment, but an increase in interlayer distance in an ethanol vapor environment.

[0172] Example 4: Separation characteristics of water-ethanol binary vapor using graphene oxide membrane

[0173] 1. Test objects: mGO membrane prepared in Example 1, graphene peroxide membrane (pGO membrane) prepared in Example 1, and fluorinated graphene oxide membrane (fGO membrane) prepared in Example 2.

[0174] 2. Test method: The test method is the same as that used in Example 2 for the binary mixture solution (2:8 weight ratio of water-ethanol mixture), and it also undergoes leakage test and calibration test.

[0175] 3. Test Results:

[0176] Figure 15-18 The results of thermally driven vapor permeation separation of water-ethanol binary vapor using graphene oxide membrane were demonstrated. Considering that the graphene oxide membrane will be reduced starting from 80°C, the test was conducted between 35°C and 75°C.

[0177] Figure 15 The combined flow rates of water vapor and alcohol vapor (hereinafter referred to as flux) are shown in Table 1 below. The experimental data are shown in Table 1 below, in which the flux measured by the pGO membrane is the highest. Figure 16 The separation coefficients are shown in Table 2 below. The pGO membrane has a high separation coefficient for water vapor, indicating enhanced selective permeation ability of water. The fGO membrane has a separation coefficient of less than 1, indicating that the proportion of ethanol in the permeate is greater than that of water.

[0178] Figure 17 and Figure 18 The flow rates of water vapor through the graphene oxide membrane (referred to as water flux) and ethanol vapor through the graphene oxide membrane (referred to as ethanol flux) are shown in Tables 3-4 below.

[0179] Table 1 Flux data of graphene oxide membranes

[0180]

[0181] Table 2 Separation coefficient data for graphene oxide membranes

[0182]

[0183] Table 3 Water flux data of graphene oxide membrane

[0184]

[0185] Table 4. Ethanol flux data of graphene oxide membranes

[0186]

[0187] The results showed that the water flux of the pGO membrane was greater than that of the mGO membrane, but the ethanol flux of the pGO membrane was almost similar to that of the mGO membrane. The flux of ethanol vapor through the fGO membrane was much higher than that of water vapor and the flux of ethanol vapor through other membranes.

[0188] It is worth noting that, such as Figure 11 As shown, no ethanol permeation was detected in the mGO and pGO membranes during the pure ethanol vapor permeation experiment. However, a small amount of ethanol was detected permeating through the membranes in binary vapor. It should be explained that although ethanol molecules cannot permeate through the mGO and pGO membranes, the permeation of water vapor can still lead to a small amount of ethanol permeation due to intermolecular interactions. Figure 18 In this process, synergistic permeation also allows a small amount of ethanol vapor to pass through both the mGO and pGO membranes. Synergistic permeation increases with increasing temperature. It causes the permeability of ethanol vapor to increase with rising temperature. Therefore, synergistic permeation is also... Figure 16 The reason why the separation coefficient decreases with temperature.

[0189] Example 5: Comparison of separation coefficient and flux of various membranes

[0190] Figure 19The graph shows the flux separation coefficients of water-ethanol binary vapor using existing membranes (such as polymer membranes and inorganic membranes) and graphene oxide membranes. Circles represent conventional polymer membranes, triangles represent inorganic membranes, and rectangles represent graphene oxide membranes. Among them, the green circle data comes from reference [1] Fan SC, Li CL, Wang YC, et al. Application of aromatic polyamide membranes for pervaporation and vapor permeation[J]. 2002, 148(1-3): 43-48, the red circle data comes from reference [2] Lee KR, Chen RY, Lai JY. Plasma deposition of vinyl acetate onto Nylon-4 membrane for pervaporation and evapomeation separation of aqueous alcohol mixtures[J]. Journal of Membrane Science, 1992, 75(1-2): 171-180, and the brown triangle data comes from reference [3] Sato K, Sugimoto K, Nakane T. Mass-production of tubular NaY zeolite membranes for industrial purpose and their application to ethanol dehydration by vapor permeation[J]. Journal of Membrane Science, 2008, 319(1-2):244-255, the bright green circle and the yellowish-brown circle are from reference [4] Teng MY, Lee KR, Fan SC, et al. Development of aromatic polyamide membranes for pervaporation and vapor permeation[J]. 2000, 164(1-2):241-249, the dark green triangle is from reference [5] Veen HMV, Delft YC V, Engelen CWR, et al. Dewatering of organics by pervaporation with silica membranes[J].2001, 22-23(none): 361-366, Blue circle from reference [6] Yonglie Wu, Peng X, Liu J, et al. Study on the integrated membrane processes of dehumidification of compressed air and vapor permeation processes[J]. Journal of Membrane Science, 2002, Brown circle from reference [7] Yeh JM, Yu MY, Liou SJ. Dehydration of water–alcohol mixtures by vapor permeation through PVA / claynanocomposite membrane[J]. Journal of Applied Polymer Science, 2010, 89(13): 3632-3638.

[0191] To provide a better comparison with the separation factor-flux of graphene oxide membranes, the nGO membrane in Raw Material Preparation Example 3 and the commercially available perapap 4101 membrane were compared. Figure 19 The flux and separation coefficient of the solution (circle marked with the ∧ symbol) were tested. The test method was the same as the formal test method for the binary mixture solution (2:8 weight ratio water-ethanol mixture) in Example 2, and it also underwent leakage test and calibration test. Figure 19 The flux and separation factor data for all graphene oxide membranes and commercially available Perapap 4101 membranes were measured at 35°C, as detailed in Table 5 below.

[0192] Table 5 Comparison of Separation Coefficients and Fluxes of Various Membrane Types

[0193]

[0194] The results show that the main limitation of polymer membranes lies in their flux. Although some polymer membranes have good separation coefficients, the flux of most polymer membranes is limited to 1000 g·m³. -2 ·h -1 Approximately. It is well known that polymer membranes have relatively weak chemical resistance and thermal stability. Since the membrane is primarily exposed to alcohol solvent vapors, its chemical resistance is a key factor for vapor permeation.

[0195] Inorganic membranes have become a research hotspot in recent years due to their excellent chemical resistance, mechanical strength, and thermal stability. For example... Figure 19As shown, although inorganic membranes exhibit better performance than polymer membranes, especially in terms of flux, inorganic membrane materials are more difficult to process and relatively expensive due to their brittleness.

[0196] Both mGO and pGO membranes exhibit high flux and high separation coefficients. mGO membranes show a flux one order of magnitude higher than polymer membranes, and pGO membranes even show a flux two orders of magnitude higher than inorganic membranes, as detailed in Table 5. As a vapor permeation membrane, GO is a material of great interest because it combines all the advantages of polymer and inorganic membranes, such as excellent chemical resistance and mechanical strength, ease of fabrication, and good thermal stability.

[0197] Example 6: Interlayer distance between graphene oxide layers in graphene oxide films under various binary vapor environments.

[0198] 1. Test objects: mGO membrane prepared in Example 1, graphene peroxide membrane (pGO membrane) prepared in Example 1, and fluorinated graphene oxide membrane (fGO membrane) prepared in Example 2.

[0199] 2. Test Results:

[0200] like Figure 20-23 As shown (XRD measurement, using industry-standardized testing methods), Figure 20-23 The interlayer distances of mGO, pGO, and fGO membranes, as measured by XRD, are reflected in mixed vapors of water and methanol, water and ethanol, water and isopropanol, and water and n-butanol, respectively, with a weight ratio of 1:1 for each alcohol and water.

[0201] like Figure 20 Based on the 2θ corresponding to the peak value in the figure, and using the Bragg equation 2dsinθ=nλ (λ=0.15406nm, n=1), the interlayer distances d of the mGO, pGO, and fGO membranes in a mixed vapor environment of water and methanol with a weight ratio of 1:1 are calculated as follows: and Similarly, from Figure 21 As can be seen from the data, the interlayer distances d of the mGO membrane, pGO membrane, and fGO membrane in a mixed vapor environment of water and ethanol with a weight ratio of 1:1 are respectively and from Figure 22 As can be seen from the data, the interlayer distances d of the mGO, pGO, and fGO membranes in a mixed vapor environment of water and isopropanol with a weight ratio of 1:1 are respectively and from Figure 23As can be seen from the data, the interlayer distances d of the mGO, pGO, and fGO membranes in a mixed vapor environment of water and n-butanol with a weight ratio of 1:1 are respectively... and

[0202] Figure 20-23 The results show that the interlayer distances of mGO, pGO, and fGO films are different, and that the interlayer distances are variable in different binary gas phases. In a water-methanol mixed solution, the interlayer distance (e.g., Figure 20 ) compared to other situations ( Figure 21-23 The membrane is larger, so more molecules can be transported through it.

[0203] Example 7: Separation characteristics of various binary vapors using graphene oxide membranes

[0204] 1. Test objects: mGO membrane prepared in Example 1, graphene peroxide membrane (pGO membrane) prepared in Example 1, and fluorinated graphene oxide membrane (fGO membrane) prepared in Example 2.

[0205] 2. Test Method: The test method is the same as that used in Example 2 for the binary mixture solution (2:8 weight ratio of water-ethanol mixture), and it also underwent leakage and calibration tests. The mass ratio of water to alcohol was 2:8 in all experiments.

[0206] 3. Test Results:

[0207] Figure 24-27 Results of separating various water-alcohol binary vapors using graphene oxide membranes (mGO, pGO, and fGO) are presented, including binary vapors of methanol (MeOH), isopropanol (IPA), and n-butanol (BuOH) with water. The results show that pGO and fGO membranes can separate water and alcohols from binary feed vapors, respectively.

[0208] Figure 24 and Figure 25 The flux (sum of water vapor and alcohol vapor flow rates) and separation coefficient through the pGO membrane are shown in Table 6-7 below.

[0209] Figure 26 and Figure 27 The flux (sum of water vapor and alcohol vapor flow rates) and separation coefficient through the fGO membrane are shown in Tables 8-9 below.

[0210] Table 6. Flux data for pGO membranes

[0211]

[0212] Table 7. Separation coefficient data for pGO membranes

[0213]

[0214] Table 8. Flux data for fGO membranes

[0215]

[0216] Table 9. Separation coefficient data for fGO membranes

[0217]

[0218] The results showed that pGO and fGO membranes exhibited significant differences in flux and separation coefficient. Example 8: Separation characteristics of various binary vapors using graphene oxide membranes – interlayer distance correlation

[0219] Figure 28-31 In this study, the flux and separation coefficient of graphene oxide films were correlated with the interlayer distance. The flux and separation coefficient data were measured at 35°C.

[0220] Figure 28 and Figure 29 The flux of pGO membranes and fGO membranes as a function of interlayer distance were shown.

[0221] Figure 30 and Figure 31 The separation coefficients of pGO and fGO membranes as a function of interlayer distance were shown.

[0222] It is evident that the variation in interlayer distance with the binary gas phase also leads to... Figure 28-31 One of the reasons for the pattern.

Claims

1. A graphene oxide film, characterized in that, In its Fourier transform infrared spectrum, the area at 1840-1860 cm⁻¹ -1 The band exhibits vibrational peaks; the ratio of the number of carbon atoms on its surface to the number of oxygen atoms on its surface is (1-1.5):

1.

2. The graphene oxide film according to claim 1, characterized in that, In the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 850-890 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the -C-OH group; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1240-1270 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the -COC bond; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1410-1430 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the -COOH group; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1600-1630 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the -COOH group; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1720-1750 cm⁻¹ range... -1 A vibration peak exists in the band; this vibration peak is preferably the vibration peak of the C=O bond; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1840-1860 cm⁻¹ range... -1 The band contains vibrational peaks of C=O bonds; Preferably, the Fourier transform infrared spectrum of the surface of the graphene oxide film is shown in Figure 2; And / or, the ratio of the number of carbon atoms on the surface of the graphene oxide film to the number of oxygen atoms on the surface of the graphene oxide film is 1.25:1; And / or, the oxygen atom content on the surface of the graphene oxide film is 40%-50%, for example 44.4%, where the percentage is the percentage of the number of oxygen atoms on the surface of the graphene oxide film to the sum of the number of oxygen atoms and carbon atoms on the surface of the graphene oxide film; And / or, the carbon atom content on the surface of the graphene oxide film is 50%-60%, for example 55.6%, where the percentage is the percentage of the number of carbon atoms on the surface of the graphene oxide film to the sum of the number of oxygen atoms and carbon atoms on the surface of the graphene oxide film; Preferably, the energy dispersive spectrum of the elemental analysis of the surface of the graphene oxide film is shown in Figure 5; And / or, the thickness of the graphene oxide film is 0.3-0.4 μm, for example 0.33 μm; And / or, in a dry environment, the interlayer distance between the graphene oxide layers in the graphene oxide film is... For example And / or, in water vapor, the interlayer distance between the graphene oxide layers in the graphene oxide film is 12- For example, And / or, in ethanol vapor, the interlayer distance between the graphene oxide layers is... For example, And / or, in a mixture of water and methanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, And / or, in a mixture of water and ethanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, And / or, in a mixture of water and isopropanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, And / or, in a mixture of water and n-butanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, 3. A method for preparing a graphene oxide film, characterized in that, It includes the following steps: The mGO membrane was treated with O2 plasma.

4. The method for preparing the graphene oxide film according to claim 3, characterized in that, The ratio of plasma O2 flux to the surface area of ​​the mGO membrane is not less than 20 sccm / in 2 ; And / or, the method for preparing the mGO membrane includes the following steps: dispersing mGO in water by ultrasonication to form an mGO dispersion, then filtering the mGO dispersion under vacuum while drying on a filter membrane support layer to obtain an mGO membrane; preferably, mGO is prepared by the following method: dispersing graphite powder in concentrated sulfuric acid; then cooling the dispersion to 10°C; subsequently, adding potassium permanganate and stirring at no more than 30°C for no more than 3 hours; then pouring the reaction mixture onto ice and adding hydrogen peroxide dropwise until the gas is completely released, and obtaining mGO by filtration; preferably, the weight ratio of graphite powder to potassium permanganate is 1:3; preferably, the concentration of hydrogen peroxide is 30 wt%; preferably, the amounts of graphite powder, concentrated sulfuric acid, and hydrogen peroxide are 1 kg: 30 L: 0.3 L; And / or, the processing equipment used is an etching machine; preferably, the ratio of the microwave power of the etching machine to the surface area of ​​the mGO film is not less than 20 W / in. 2 ; And / or, the vacuum level of the environment in which the treatment is performed is 0.1-1 torr; And / or, the ratio of the processing time to the surface area of ​​the mGO membrane is not less than 60 s / in. 2 .

5. A graphene oxide film, characterized in that, It is prepared according to the method for preparing graphene oxide film as described in claim 3 or 4.

6. A graphene oxide film, characterized in that, Its surface includes the following groups: semi-ionic CF bonds or covalent CF bonds, and the ratio of the number of fluorine atoms on its surface to the number of oxygen atoms on its surface is (0.19-0.30):

1.

7. The graphene oxide film according to claim 6, characterized in that, The surface of the graphene oxide film includes the following groups: semi-ionic CF bonds and covalent CF bonds; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 850-890 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the -C-OH group; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1035-1050 cm⁻¹ range... -1 A vibration peak exists in the band; this vibration peak is preferably in the CF band. x Vibrational peaks of functional groups, where x>1; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1160-1190 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the CF bond in the half-ion. And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1260-1290 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably a vibrational peak of a covalent CF bond; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1720-1760 cm⁻¹ range... -1 A vibration peak exists in the band; this vibration peak is preferably the vibration peak of the C=O bond; And / or, in the Fourier transform infrared spectrum of the surface of the graphene oxide film, in the 1850-1890 cm⁻¹ range... -1 A vibrational peak exists in the band; this vibrational peak is preferably the vibrational peak of the FC=O group; Preferably, the Fourier transform infrared spectrum of the surface of the graphene oxide film is shown in Figure 3; And / or, the ratio of the number of fluorine atoms on the surface of the graphene oxide film to the number of oxygen atoms on the surface of the graphene oxide film is preferably 0.289:1; And / or, the ratio of the number of carbon atoms on the surface of the graphene oxide film to the number of oxygen atoms on the surface of the graphene oxide film is (6-8):1, for example 7.17:1; And / or, the oxygen atom content on the surface of the graphene oxide film is less than 10%, preferably 7%-9.5%, for example 8.6%, the percentage being the percentage of the number of oxygen atoms on the surface of the graphene oxide film to the sum of the number of oxygen atoms, fluorine atoms and carbon atoms on the surface of the graphene oxide film; And / or, the fluorine atom content on the surface of the graphene oxide film is 20%-40%, preferably 28%-36%, for example 29.75%, the percentage being the percentage of the number of fluorine atoms on the surface of the graphene oxide film to the sum of the number of oxygen atoms, fluorine atoms and carbon atoms on the surface of the graphene oxide film; And / or, the carbon atom content on the surface of the graphene oxide film is 61.65%, which is the percentage of the number of carbon atoms on the surface of the graphene oxide film to the sum of the number of oxygen atoms, fluorine atoms and carbon atoms on the surface of the graphene oxide film. Preferably, the energy dispersive spectrum of the elemental analysis of the surface of the graphene oxide film is shown in Figure 6; And / or, the thickness of the graphene oxide film is 0.3-0.4 μm, for example 0.33 μm; And / or, in a dry environment, the interlayer distance between the graphene oxide layers in the graphene oxide film is... For example And / or, in water vapor, the interlayer distance between the graphene oxide layers is... For example, And / or, in ethanol vapor, the interlayer distance between the graphene oxide layers is... For example, And / or, in a mixture of water and methanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, And / or, in a mixture of water and ethanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, And / or, in a mixture of water and isopropanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, And / or, in a mixture of water and n-butanol vapor at a weight ratio of 1:1, the interlayer distance between the graphene oxide layers is [missing information]. For example, 8. A method for preparing a graphene oxide film, characterized in that, It includes the following steps: The mGO membrane was fluorinated with XeF2.

9. The method for preparing the graphene oxide film according to claim 8, characterized in that, The preparation method of the mGO membrane includes the following steps: dispersing mGO in water by ultrasonication to form an mGO dispersion, filtering the mGO dispersion by vacuum, and drying it on a filter membrane support layer to obtain an mGO membrane; preferably, mGO is prepared by the following method: dispersing graphite powder in concentrated sulfuric acid; then cooling the dispersion to 10°C; subsequently, adding potassium permanganate and stirring at no more than 30°C for no more than 3 hours; then pouring the reaction mixture onto ice and adding hydrogen peroxide dropwise until the gas is completely released, and obtaining mGO by filtration; the weight ratio of graphite powder to potassium permanganate is preferably 1:3; the concentration of hydrogen peroxide is preferably 30 wt%; the amount of graphite powder, concentrated sulfuric acid, and hydrogen peroxide is preferably 1 kg: 30 L: 0.3 L; And / or, the fluorination process is as follows: first, the mGO membrane is reacted with XeF2, then rinsed, completing a pulse reaction cycle, and the fluorination process is completed for at least 2 pulse reaction cycles; preferably, the ratio of the reaction time to the surface area of ​​the mGO membrane is not less than 15 s / in. 2 The rinsing is preferably performed using nitrogen or an inert gas; the fluorination treatment is preferably completed in 10 pulse reaction cycles. And / or, the fluorination treatment is performed at a temperature of 0-40°C; And / or, during the fluorination treatment, the pressure of the XeF2 is not less than 3000 mTorr.

10. A graphene oxide film, characterized in that, It is prepared according to the method for preparing graphene oxide film as described in claim 8 or 9.

11. Application of a graphene oxide membrane in vapor permeation of a water-organic solvent system.

12. The application of the graphene oxide film according to claim 11, characterized in that, The graphene oxide membrane is an nGO membrane, a mGO membrane, or a graphene oxide membrane as described in any one of claims 1, 2, 5, 6, 7, and 10; the nGO membrane is preferably prepared by the following steps: dispersing nGO in water by ultrasonication to form an nGO dispersion, then filtering the nGO dispersion under vacuum while drying it on a filter membrane support layer to obtain an nGO membrane; the mGO membrane is preferably prepared by the following steps: dispersing mGO in water by ultrasonication to form an mGO dispersion, then filtering the mGO dispersion under vacuum while drying it on a filter membrane support layer to obtain an mGO membrane; And / or, the organic solvent is one or more of alcohol solvents, ester solvents, ketone solvents, and amide solvents; the alcohol solvent is preferably one or more of methanol, ethanol, isopropanol, and n-butanol; the ester solvent is preferably one or more of ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, and methyl ethyl carbonate; the ketone solvent is preferably methylpyrrolidone; and the amide solvent is preferably dimethylacetamide. Preferably, the water-organic solvent system is a water-methanol binary system, a water-isopropanol binary system, a water-n-butanol binary system, or a water-ethanol binary system; And / or, the mass ratio of the water to the organic solvent is 1:1 to 2:8; And / or, the temperature of the vapor permeation is 0-75°C, for example 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C or 75°C; And / or, the pressure of the vapor permeation is not higher than atmospheric pressure, for example, atmospheric pressure.

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