Preparation method of graphene oxide / aramid fiber / graphene oxide composite film

Abstract

The application provides a preparation method of a graphene oxide / aramid fiber / graphene oxide composite film, which comprises the following steps: adding Kevlar threads and potassium hydroxide solids into a dimethyl sulfoxide solvent, stirring at a first predetermined temperature for a first predetermined time to obtain an aramid fiber nanofiber solution; placing graphene oxide in the dimethyl sulfoxide solvent to perform ultrasonic dispersion to obtain a graphene oxide dispersion liquid; performing suction filtration after adding deionized water into the graphene oxide dispersion liquid to obtain a graphene oxide film; adding the aramid fiber nanofiber solution into the graphene oxide dispersion liquid, and then adding deionized water to perform ultrasonic treatment to obtain a mixed dispersion liquid of graphene oxide and aramid fiber; placing the mixed dispersion liquid into a fume hood after suction filtration into a film to stand overnight to obtain a peeled-off graphene oxide / aramid fiber / graphene oxide composite film, and then performing drying treatment for a second predetermined time to obtain a dried graphene oxide / aramid fiber / graphene oxide composite film.

Description

Technical Field

[0001] This invention belongs to the field of membrane material preparation, specifically relating to a method for preparing a graphene oxide / aramid fiber / graphene oxide composite membrane. Background Technology

[0002] Membrane materials, with their ultrathin thickness and macroscopically smooth surfaces, have attracted widespread attention in many fields in recent years. However, constructing novel membranes with high mechanical properties and conductivity remains a significant challenge, especially the fabrication of nanofluidic membranes with nanoscale channels for ion transport. Two-dimensional materials, such as graphene oxide, Mxenes, and C3Ni4 membranes, have been extensively studied. In addition to two-dimensional membranes, covalent organic framework (COF) membranes, with their regular pore structures, have also garnered considerable attention. However, the preparation of COF materials involves numerous organic solvents, hindering practical applications. Therefore, two-dimensional materials have received even greater attention.

[0003] However, two-dimensional materials such as graphene oxide have a very rich number of oxygen-containing functional groups on their surface. In the assembled two-dimensional channel membrane, the abundant oxygen-containing functional groups on the two-dimensional material nanosheets will combine with water molecules. The combination of water molecules not only simply increases the nanopores of the two-dimensional material, but more importantly, it damages the stability of the two-dimensional membrane in water, which greatly limits the application range of two-dimensional materials in practice.

[0004] Recently, composite materials have attracted widespread attention from researchers. For example, researchers have recently developed a two-dimensional heterogeneous channel membrane, a heterogeneous composite membrane with nanoscale channels assembled from graphene oxide and g-C3N4. This membrane can form very stable layered channels and exhibits excellent mechanical properties and water stability. Furthermore, graphene oxide can be combined with other two-dimensional materials, such as boron nitride two-dimensional membranes, to form heterogeneous two-dimensional composite membranes. The resulting membranes exhibit excellent water stability and can be used for salinity gradient energy capture. Finally, this membrane demonstrates excellent mechanical and performance stability in water.

[0005] Based on the above background, and considering the possibility of preparing composites not only within the same dimension but also assembling composites of different dimensions, aramid fiber (ANF) exhibits very strong mechanical stability due to its primary composition of poly(p-phenylene terephthalamide) (PPTA) polymer chains. PPTA polymer chains contain abundant nitrogen, oxygen, and hydrogen atoms, resulting in abundant hydrogen bonds between the polymer chains, thus increasing the mechanical strength of ANF itself. Furthermore, combining ANF with GO can enhance the mechanical stability of the GO / ANF / GO composite film. Utilizing the auxiliary effect of hydrogen bonds between GO and ANF, through superassembly, a GO / ANF / GO composite film with a shell-like structure and high mechanical properties can be prepared, enabling its application in multiple fields. Summary of the Invention

[0006] This invention is made to solve the above-mentioned problems, and its purpose is to provide a method for preparing a graphene oxide / aramid fiber / graphene oxide composite film.

[0007] This invention provides a method for preparing a graphene oxide / aramid fiber / graphene oxide composite film, characterized by the following steps: Step 1, adding Kevlar fibers and solid potassium hydroxide to a dimethyl sulfoxide solvent, stirring at a first predetermined temperature for a first predetermined time to obtain a dark red aramid fiber nanofiber solution; Step 2, placing graphene oxide in a dimethyl sulfoxide solvent, and then ultrasonically dispersing it to obtain a graphene oxide dispersion; Step 3, adding deionized water to the graphene oxide dispersion, and then filtering the graphene oxide dispersion to obtain pure graphene oxide. Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of 5wt% to 80wt% aramid fiber nanofiber solution in the graphene oxide dispersion. Then add deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber. Step 5: Filter the mixed dispersion to form a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then perform a second predetermined drying treatment to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0008] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite film provided by the present invention may also have the following characteristics: in step 1, the first predetermined temperature is 30℃~50℃ and the first predetermined time is 7 days~10 days.

[0009] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite film provided by the present invention may also have the following feature: in step 2, the size of the graphene oxide nanosheets in the graphene oxide dispersion is 3μm to 5μm.

[0010] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane provided by the present invention may also have the following features: in step 3, vacuum filtration is used, and the filter membrane used is an anodic aluminum oxide filter membrane with a pore size of 80 nm.

[0011] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite film provided by the present invention may also have the following feature: in step 4, the aramid fiber nanofiber solution in the graphene oxide dispersion is 80 wt%.

[0012] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane provided by the present invention may also have the following features: in step 5, vacuum filtration is used, and the filter membrane used is an anodic aluminum oxide filter membrane with a pore size of 80 nm.

[0013] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite film provided by the present invention may also have the following features: in step 5, the drying process is carried out in a forced-air drying oven, and the temperature in the forced-air drying oven is 80℃~85℃, and the second predetermined time is 24h.

[0014] The method for preparing the graphene oxide / aramid fiber / graphene oxide composite film provided by the present invention may also have the following characteristics: in step 5, the thickness of the dried graphene oxide / aramid fiber / graphene oxide composite film is 5μm to 10μm, and the two-dimensional channel size is 0.6nm to 0.8nm.

[0015] The role and effect of invention

[0016] This invention utilizes the hydrogen bonding between aramid fibers and graphene oxide. With the assistance of hydrogen bonding, aramid fibers and graphene oxide undergo cross-dimensional superassembly. With the assistance of vacuum filtration, a GO / ANF / GO composite membrane is prepared. Due to the hydrogen bonding, the prepared composite membrane has regular 2D channels and very good mechanical stability.

[0017] Furthermore, an anolyl alumina (AAO) filter membrane was used as the final filter membrane to prepare the GO / ANF / GO composite membrane. This is because during the long-term vacuum filtration process, GO gradually blocks the pores of AAO, thus slowing down the filtration process. This slow filtration process results in the formation of highly regular two-dimensional sub-nanometer channels. In addition, during the filtration process, aluminum ions from the anolyl alumina gradually penetrate into the GO membrane, forming chelation interactions with the oxygen-containing functional groups on the GO nanosheets and the oxygen-containing functional groups and nitrogen atoms on the ANF. Therefore, the stability of the GO / ANF / GO composite membrane is ultimately increased.

[0018] Furthermore, after mixing ANF and GO, a certain volume of deionized water is added. This is mainly because deionized water can accelerate hydrolysis and further increase the hydrogen bonding force between graphene oxide and aramid fibers. After vacuum filtration, the mixture undergoes further heat treatment. This heat treatment process not only increases the stability of the composite membrane but also causes the carbon structure to change from amorphous carbon to crystalline carbon.

[0019] In summary, the preparation method of this invention utilizes the hydrogen bonding forces between GO and ANF. With the assistance of these hydrogen bonds, a GO / ANF / GO composite membrane with regular two-dimensional channels is prepared via a superassembly method using an anolyl alumina (AAO) filter membrane. The prepared composite membrane exhibits excellent mechanical and water stability. Furthermore, the introduction of ANF introduces numerous hydrogen bonds into the composite membrane system, increasing its stability across a wide pH range and enabling its application in various water-based fields.

[0020] Therefore, the preparation method of this invention is a hydrogen bond-assisted superassembly method, which is simple and easy to operate. The prepared GO / ANF / GO composite membrane has excellent mechanical stability and can exist stably in aqueous solutions with a wide pH range for a long time, solving the problem that ordinary two-dimensional membranes are easy to disperse and break in water. It has very broad application prospects in many fields such as ion transport, desalination, sensing, energy conversion and nanoreactors. Attached Figure Description

[0021] Figure 1 This is a diagram of the apparatus for preparing GO / ANF / GO composite films based on the electrostatically assisted superassembly strategy of the present invention;

[0022] Figure 2 This is a schematic diagram of the arrangement of GO / ANF / GO micro-graphene oxide sheets and ANF in this invention;

[0023] Figure 3 These are optical images of the GO / ANF / GO composite film prepared in the embodiments of the present invention;

[0024] Figure 4These are scanning electron microscope comparison images of the GO membrane and the GO / ANF / GO composite membrane prepared in the embodiments of the present invention;

[0025] Figure 5 These are characterization diagrams of the mechanical properties of GO and GO / ANF / GO composite films studied in the embodiments of the present invention;

[0026] Figure 6 This is a stress variation diagram of the GO / ANF / GO composite film prepared in the embodiments of the present invention;

[0027] Figure 7 This is a stability diagram of the GO / ANF / GO composite membrane prepared in the embodiments of the present invention at different pH values;

[0028] Figure 8 The images show X-ray diffraction patterns of GO / ANF / GO composite films prepared in different proportions in the embodiments of the present invention in the dry state, as well as a comparison of the dry and wet X-ray diffraction patterns of the GO film and the GO / ANF / GO composite film. Detailed Implementation

[0029] To make the technical means and effects of the present invention easy to understand, the present invention will be specifically described below in conjunction with embodiments and accompanying drawings.

[0030] This invention provides a method for preparing a graphene oxide / aramid fiber / graphene oxide composite film, comprising the following steps:

[0031] Step 1: Kevlar filaments and potassium hydroxide solid are added to dimethyl sulfoxide solvent and stirred at a first predetermined temperature for a first predetermined time to obtain a dark red aramid fiber ANF nanofiber solution.

[0032] In this invention, the first predetermined temperature is 30℃~50℃ and the first predetermined time is 7 days~10 days. The Kevlar strips are degraded at a temperature of 30-50℃ because at this temperature, the hydrogen bonds between the poly(p-phenylene terephthalamide) (PPTA) polymer chains are opened, which allows for the formation of more hydrogen bonds with GO, thereby increasing the stability of the GO / ANF / GO composite film.

[0033] Step 2: Place graphene oxide (GO) in dimethyl sulfoxide solvent and then perform ultrasonic dispersion to obtain a graphene oxide dispersion.

[0034] In this invention, the size of the graphene oxide nanosheets in the graphene oxide dispersion is 3μm to 5μm. The GO two-dimensional nanochannel membrane prepared at this size has more regular channels.

[0035] Step 3: Add deionized water to the graphene oxide dispersion to fully deprotonate the oxygen-containing functional groups on GO. Then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0036] In this invention, vacuum filtration is used, and the filter membrane used is an anodized aluminum oxide filter membrane (AAO) with a pore size of 80 nm.

[0037] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of 5wt% to 80wt% aramid fiber nanofiber solution in the graphene oxide dispersion. Then add deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0038] In this invention, the aramid fiber nanofiber solution in the graphene oxide dispersion is 80 wt%.

[0039] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, perform a second predetermined drying treatment to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0040] In this invention, vacuum filtration is used, and the filter membrane is an anodic aluminum oxide filter membrane (AAO) with a pore size of 80 nm. The drying process is carried out in a forced-air drying oven at a temperature of 80°C to 85°C for a second predetermined time of 24 hours. The thickness of the dried graphene oxide / aramid fiber / graphene oxide composite membrane is 5 μm to 10 μm, and the two-dimensional channel size is 0.6 nm to 0.8 nm.

[0041] <Example 1>

[0042] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0043] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0044] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0045] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of 5wt% to 80wt% aramid fiber nanofiber solution in the graphene oxide dispersion. Then add 1mL to 2mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0046] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0047] <Example 2>

[0048] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0049] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0050] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0051] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a 5wt% mixture of aramid fiber nanofiber solution in the graphene oxide dispersion. Then add 1mL to 2mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0052] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0053] <Example 3>

[0054] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0055] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0056] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0057] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of aramid fiber nanofiber solution in the graphene oxide dispersion at 10 wt%. Then add 1 mL to 2 mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0058] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0059] <Example 4>

[0060] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0061] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0062] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0063] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of aramid fiber nanofiber solution in the graphene oxide dispersion at 15 wt%. Then add 1 mL to 2 mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0064] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0065] <Example 5>

[0066] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0067] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0068] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0069] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of aramid fiber nanofiber solution in the graphene oxide dispersion at 25 wt%. Then add 1 mL to 2 mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0070] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0071] <Example 6>

[0072] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0073] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0074] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0075] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of aramid fiber nanofiber solution in the graphene oxide dispersion at 50 wt%. Then add 1 mL to 2 mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0076] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0077] <Example 7>

[0078] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0079] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0080] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0081] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of aramid fiber nanofiber solution in the graphene oxide dispersion at 60 wt%. Then add 1 mL to 2 mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0082] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0083] <Example 8>

[0084] Step 1: Add 0.5g to 0.7g of Kevlar yarn and 0.6g to 0.8g of potassium hydroxide solid to 240mL to 280mL of dimethyl sulfoxide solvent, and stir at 30℃ to 50℃ for 7 to 10 days to obtain a dark red aramid fiber nanofiber solution.

[0085] Step 2: Place 100 mg to 120 mg of graphene oxide in 100 mL to 120 mL of dimethyl sulfoxide solvent, and then disperse it by ultrasonication to obtain a graphene oxide dispersion.

[0086] Step 3: Add 1 mL to 2 mL of deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane.

[0087] Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of aramid fiber nanofiber solution in the graphene oxide dispersion to 80 wt%. Then add 1 mL to 2 mL of deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber.

[0088] Step 5: Filter the mixed dispersion into a membrane and place the membrane in a fume hood overnight to obtain the peeled graphene oxide / aramid fiber / graphene oxide composite membrane. Then, dry it in a forced-air oven at 80-85℃ for 24 hours to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane.

[0089] Figure 1 The diagram shows the apparatus for preparing GO / ANF / GO composite membranes by hydrogen bond-assisted superassembly in various embodiments of the present invention. In this embodiment, anodic aluminum oxide (AAO) is used as the filter membrane, and the final GO / ANF / GO composite membrane is prepared by vacuum filtration. Figure 2 This is a schematic diagram of the arrangement of GO / ANF / GO micro-graphene oxide sheets and ANF in this invention. Figure 3 The image shown is an optical image of the GO / ANF / GO composite film prepared in the example.

[0090] Figure 3 (a) shows the GO / ANF / GO composite membrane on the surface of the AAO filter membrane immediately after filtration, at which point the GO / ANF / GO composite membrane is tightly adhered to the AAO surface. Figure 3 (b) is an independent, self-supporting GO / ANF / GO composite film that has been dried in a fume hood and peeled off from the AAO surface. Figure 3 (c) indicates that the prepared GO / ANF / GO composite membrane exhibits flexibility that allows it to be bent and folded.

[0091] Depend on Figure 3 It can be seen that the GO / ANF / GO composite membranes prepared in Examples 1 to 7 have bendable flexibility, among which the GO / ANF / GO composite membrane prepared in Example 8, which contains 80wt% ANF, has the best flexibility.

[0092] Figure 4These are morphological characterization images of the GO / ANF / GO composite membrane, in which... Figure 4 (a) is a cross-sectional view of a simple graphene oxide film, showing a layered stacked structure. Figure 4 (b) is a cross-sectional view of the GO / ANF / GO composite membrane containing 5wt% ANF, which still exhibits a very regular layered structure.

[0093] The GO or GO / ANF / GO composite films prepared in each embodiment were first characterized using scanning electron microscopy. The prepared GO and GO / ANF / GO composite films were cut and pasted onto the surface of conductive adhesive using scissors, and then cross-sectional views of the composite films were scanned using scanning electron microscopy.

[0094] from Figure 4 As can be seen from the cross-sectional morphology diagram, the thickness of the GO / ANF / GO composite films prepared in Examples 1 to 7 is about 5 μm, and they exhibit a distinct layered structure. Among them, the thickness of the GO / ANF / GO composite film in Example 2 is 5 μm, and the layered structure is the most obvious.

[0095] Figure 5 This is a characterization diagram of the mechanical properties of the GO / ANF / GO composite membrane, in which... Figure 5 (a) is a graph showing the GO membrane dispersed in water and sonicated for 2 hours. Figure 5 (b) is a graph showing the GO / ANF / GO-80% membrane dispersed in water and sonicated for 2 hours.

[0096] A piece was cut from the GO membrane and the GO / ANF / GO composite membrane, placed in deionized water, and then sonicated for 2 hours for observation. Figure 5 It was found that the prepared composite membrane maintained a very good morphology after 2 hours of sonication; however, the GO membrane quickly dispersed in the water and could not maintain its structure. Among them, the GO / ANF / GO composite membrane in Example 8 maintained the best morphology after 2 hours of sonication.

[0097] Figure 6 This is a stress variation diagram of the GO / ANF / GO composite film prepared in an embodiment of the present invention, wherein, Figure 6 (a) is a tensile stress diagram of a simple GO film. Figure 6 (b) is the tensile stress diagram of GO / ANF / GO-5%. Figure 6 (c) is the tensile stress diagram of GO / ANF / GO-10%. Figure 6 (d) is the tensile stress diagram of GO / ANF / GO-15%. Figure 6 (e) is the tensile stress diagram of GO / ANF / GO-25%. Figure 6(f) is the tensile stress diagram of GO / ANF / GO-50%. Figure 6 (g) is the tensile stress diagram of GO / ANF / GO-60%. Figure 6 (h) is the tensile stress diagram of GO / ANF / GO-80%.

[0098] The mechanical properties of the composite film were then tested using a universal tensile tester. The test process involved a 5N test pressure, a tensile rate of 1mm / min, and a 10mm test fixture. Figure 6 This indicates that the mechanical properties of the GO / ANF / GO composite membrane are indeed far superior to those of the GO membrane, demonstrating that the introduction of ANF can indeed enhance the mechanical properties of two-dimensional membranes. Among them, the membrane in Example 8, which still maintains a very good morphology, exhibits the best mechanical properties and has potential application value in membrane science, seawater desalination, and desalination fields.

[0099] Subsequently, GO and GO / ANF / GO composite membranes were placed in deionized water at different pH values. After half a month, the GO / ANF / GO composite membrane still maintained a very good membrane structure at different pH values, indicating that the GO / ANF / GO composite membrane has excellent water stability. Among them, Example 8 showed the best water stability.

[0100] Figure 8 This is a material characterization diagram of the GO / ANF / GO composite membrane.

[0101] Figure 8 (a) shows the X-ray diffraction patterns of the prepared GO and GO / ANF / GO composite films in the dry state. It can be seen that the prepared composite films are two-dimensional films with sub-nanometer channels. Furthermore, the addition of ANF reduces the interlayer spacing of the two-dimensional channels in the GO / ANF / GO composite film due to the hydrogen bonds formed between ANF and GO, which verifies the strong hydrogen bonding between GO and ANF. In addition, the introduction of ANF also increases the stability of the composite film. Figure 8 (b) A comparison of the X-ray diffraction patterns of the GO membrane alone and the GO / ANF / GO composite membrane under dry and wet conditions was recorded, and it was found that the introduction of ANF increases the stability of the GO / ANF / GO composite membrane.

[0102] The role and effect of the embodiments

[0103] As can be seen from Examples 1 to 8, when the aramid fiber nanofiber solution in the graphene oxide dispersion is 80 wt%, the prepared GO / ANF / GO composite membrane has the best mechanical properties and the best water stability.

[0104] This invention utilizes the hydrogen bonding between aramid fibers and graphene oxide. With the assistance of hydrogen bonding, aramid fibers and graphene oxide undergo cross-dimensional superassembly. With the assistance of vacuum filtration, a GO / ANF / GO composite membrane is prepared. Due to the hydrogen bonding, the prepared composite membrane has regular 2D channels and very good mechanical stability.

[0105] Furthermore, an anolyl alumina (AAO) filter membrane was used as the final filter membrane to prepare the GO / ANF / GO composite membrane. This is because during the long-term vacuum filtration process, GO gradually blocks the pores of AAO, thus slowing down the filtration process. This slow filtration process results in the formation of highly regular two-dimensional sub-nanometer channels. In addition, during the filtration process, aluminum ions from the anolyl alumina gradually penetrate into the GO membrane, forming chelation interactions with the oxygen-containing functional groups on the GO nanosheets and the oxygen-containing functional groups and nitrogen atoms on the ANF. Therefore, the stability of the GO / ANF / GO composite membrane is ultimately increased.

[0106] Furthermore, after mixing ANF and GO, a certain volume of deionized water is added. This is mainly because deionized water can accelerate hydrolysis and further increase the hydrogen bonding force between graphene oxide and aramid fibers. After vacuum filtration, the mixture undergoes further heat treatment. This heat treatment process not only increases the stability of the composite membrane but also causes the carbon structure to change from amorphous carbon to crystalline carbon.

[0107] In summary, the preparation method of this invention utilizes the hydrogen bonding forces between GO and ANF. With the assistance of these hydrogen bonds, a GO / ANF / GO composite membrane with regular two-dimensional channels is prepared via a superassembly method using an anolyl alumina (AAO) filter membrane. The prepared composite membrane exhibits excellent mechanical and water stability. Furthermore, the introduction of ANF introduces numerous hydrogen bonds into the composite membrane system, increasing its stability across a wide pH range and enabling its application in various water-based fields.

[0108] Therefore, the preparation method of this invention is a hydrogen bond-assisted superassembly method, which is simple and easy to operate. The prepared GO / ANF / GO composite membrane has excellent mechanical stability and can exist stably in aqueous solutions with a wide pH range for a long time, solving the problem that ordinary two-dimensional membranes are easy to disperse and break in water. It has very broad application prospects in many fields such as ion transport, desalination, sensing, energy conversion and nanoreactors.

[0109] The above embodiments are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A method for preparing a graphene oxide / aramid fiber / graphene oxide composite film, characterized in that, Includes the following steps: Step 1: Kevlar filaments and potassium hydroxide solid are added to dimethyl sulfoxide solvent and stirred at a first predetermined temperature for a first predetermined time to obtain a dark red aramid fiber nanofiber solution. Step 2: Place graphene oxide in dimethyl sulfoxide solvent and then disperse it by ultrasonication to obtain a graphene oxide dispersion. Step 3: Add deionized water to the graphene oxide dispersion, and then filter the graphene oxide dispersion to obtain a pure graphene oxide membrane. Step 4: Add the aramid fiber nanofiber solution to the graphene oxide dispersion to prepare a mixture of 5 wt% to 80 wt% aramid fiber nanofiber solution in the graphene oxide dispersion. Then add deionized water and perform ultrasonic treatment to obtain a mixed dispersion of graphene oxide and aramid fiber. Step 5: Filter the mixed dispersion to form a membrane, and place the membrane in a fume hood overnight to obtain the exfoliated graphene oxide / aramid fiber / graphene oxide composite membrane. Then, perform a second predetermined drying treatment to obtain the dried graphene oxide / aramid fiber / graphene oxide composite membrane. In step 5, vacuum filtration is used, and the filter membrane used is anodized aluminum membrane.

2. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane according to claim 1, characterized in that: in, In step 1, the first predetermined temperature is 30℃~50℃, and the first predetermined time is 7 days~10 days.

3. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane according to claim 1, characterized in that: in, In step 2, the size of the graphene oxide nanosheets in the graphene oxide dispersion is 3μm~5μm.

4. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane according to claim 1, characterized in that: in, In step 3, vacuum filtration is used, and the filter membrane used is an anodized aluminum filter membrane with a pore size of 80nm.

5. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane according to claim 1, characterized in that: in, In step 4, the aramid fiber nanofiber solution in the graphene oxide dispersion is 80 wt%.

6. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane according to claim 1, characterized in that: in, In step 5, the filter membrane used is an anodized aluminum filter membrane with a pore size of 80 nm.

7. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite membrane according to claim 1, characterized in that: in, In step 5, the drying process uses a forced-air drying oven, and the temperature inside the forced-air drying oven is 80℃~85℃. The second scheduled time is 24 hours.

8. The method for preparing the graphene oxide / aramid fiber / graphene oxide composite film according to claim 1, characterized in that: in, In step 5, the thickness of the dried graphene oxide / aramid fiber / graphene oxide composite film is 5μm~10μm, and the two-dimensional channel size is 0.6nm~0.8nm.

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