Modified graphene and method for preparing and use thereof

Abstract

The application relates to modified graphene and a preparation method and application thereof. The preparation method of the modified graphene comprises the following steps: mixing a dispersing agent, an organic acid and graphite in a first dispersion medium to obtain a first dispersion system, performing liquid phase stripping treatment on the first dispersion system to obtain a graphene suspension; removing unstripped graphite in the graphene suspension to obtain a graphene dispersion liquid; performing solid-liquid separation treatment on the graphene dispersion liquid to obtain a solid-phase graphene raw material; mixing the solid-phase graphene raw material, an inorganic corrosion inhibitor and a surfactant in a second dispersion medium to obtain a second dispersion system, and performing heat preservation treatment on the second dispersion system. The preparation method of the modified graphene can prepare the modified graphene which has good corrosion resistance, good dispersing performance and is not prone to agglomeration, so that the modified graphene can be used as a stable corrosion-resistant filler.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of graphene, in particular to a modified graphene and a preparation method and application thereof. BACKGROUND

[0002] Graphene has good anti-permeability, and can be used as a corrosion-resistant filler in a corrosion-resistant coating to enhance the physical barrier effect of the corrosion-resistant coating matrix. Meanwhile, graphene has an ultrahigh specific surface area and can load corrosion inhibitors to further increase the corrosion-resistant capability of the corrosion-resistant coating.

[0003] However, the effect of traditional graphene loaded with corrosion inhibitors is limited, and the graphene is prone to agglomeration due to strong π-π interaction and van der Waals force between graphene layers. This not only hinders the uniform distribution of graphene in the corrosion-resistant coating and reduces the protection effect, but also may cause cracks and cavities in the corrosion-resistant coating, resulting in a decrease in the density and protection capability of the corrosion-resistant coating. SUMMARY

[0004] Therefore, it is necessary to provide a modified graphene and a preparation method and application thereof. The preparation method of the modified graphene can prepare modified graphene with good corrosion-resistant performance, good dispersion performance and low agglomeration, so that the modified graphene can be used as a stable corrosion-resistant filler.

[0005] In a first aspect, the present application provides a preparation method of modified graphene, comprising the following steps:

[0006] mixing a dispersant, an organic acid and graphite in a first dispersion medium to obtain a first dispersion system, and performing liquid phase exfoliation treatment on the first dispersion system to obtain a graphene suspension;

[0007] removing unexfoliated graphite in the graphene suspension to obtain a graphene dispersion;

[0008] performing solid-liquid separation treatment on the graphene dispersion to obtain a solid-phase graphene raw material;

[0009] mixing the solid-phase graphene raw material, an inorganic corrosion inhibitor and a surfactant in a second dispersion medium to obtain a second dispersion system, and performing heat preservation treatment on the second dispersion system.

[0010] In some embodiments, the dispersant comprises at least one of polyvinyl alcohol, dopamine, sodium polystyrene sulfonate, sodium dodecyl benzene sulfonate and polyvinylpyrrolidone.

[0011] In some embodiments, the organic acid comprises at least one of citric acid, phytic acid, acetic acid and ascorbic acid.

[0012] In some embodiments, the inorganic corrosion inhibitor includes at least one of cerium nitrate, cerium chloride, lanthanum nitrate, lanthanum chloride, lanthanum carbonate, sodium silicate, sodium phosphate, and sodium molybdate.

[0013] In some embodiments, the graphite is 300 mesh to 1000 mesh graphite.

[0014] In some embodiments, the mass ratio of the organic acid to the graphite in the first dispersion system is (1-2):10.

[0015] In some embodiments, the mass ratio of the dispersant to the graphite in the first dispersion system is (1-2):1.

[0016] In some embodiments, the concentration of the organic acid in the first dispersion system is 10 mg / mL to 20 mg / mL.

[0017] In some embodiments, the concentration of the dispersant in the first dispersion system is 1 mg / mL to 2 mg / mL.

[0018] In some embodiments, the concentration of the graphite in the first dispersion system is 10 mg / mL to 20 mg / mL.

[0019] In some embodiments, the concentration of the solid-phase graphene raw material in the second dispersion system is 0.5 mg / mL to 2 mg / mL.

[0020] In some embodiments, the concentration of the inorganic corrosion inhibitor in the second dispersion system is 3 mg / mL to 6 mg / mL.

[0021] In some embodiments, the surfactant includes at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyl dimethyl benzyl ammonium chloride, and dodecyl dimethyl benzyl ammonium chloride.

[0022] In some embodiments, the concentration of the surfactant in the second dispersion system is 2 mg / mL to 10 mg / mL.

[0023] In some embodiments, the temperature of the heat preservation treatment is 40°C to 90°C.

[0024] In some embodiments, the time of the heat preservation treatment is 2 h to 3 h.

[0025] In some embodiments, the first dispersion system is obtained by mixing a dispersant, an organic acid, and graphite in a first dispersion medium, and the liquid-phase exfoliation treatment of the first dispersion system includes the following steps:

[0026] dissolving the dispersant and the organic acid in deionized water to obtain a first solution;

[0027] dispersing the graphite in a first organic solvent to obtain a first dispersion;

[0028] mixing the first solution and the first dispersion, and shearing the mixed solution at a speed of 10000 rpm to 15000 rpm.

[0029] In some embodiments, removing the unexfoliated graphite from the graphene suspension includes the following steps:

[0030] centrifuging the graphene suspension at a speed of 500 rpm to 1000 rpm to precipitate the unexfoliated graphite, to obtain the graphene dispersion.

[0031] In some embodiments, performing solid-liquid separation on the graphene dispersion includes the following steps:

[0032] centrifuging the graphene dispersion at a speed of 9000 rpm to 12000 rpm to obtain a graphene precipitate.

[0033] In some embodiments, the method further includes the following steps after the heat preservation of the second dispersion system:

[0034] centrifuging the second dispersion system at a speed of 9000 rpm to 12000 rpm to obtain a modified graphene precipitate;

[0035] freezing and drying the modified graphene precipitate at -40°C to -20°C for 24 h to 36 h, and crushing and sieving the modified graphene precipitate to obtain a modified graphene powder.

[0036] In a second aspect, the present application provides a modified graphene, which is prepared by the method for preparing the modified graphene according to any one of the above aspects, and includes a graphene body, an organic acid and an inorganic corrosion inhibitor; the inorganic corrosion inhibitor is loaded on the graphene body by the organic acid.

[0037] In a third aspect, the present application provides an application of the modified graphene according to the above or prepared by the method for preparing the modified graphene according to any one of the above aspects, as a corrosion-resistant filler in a corrosion-resistant coating.

[0038] In the preparation method of the modified graphene, the graphene with relatively perfect lattice structure can be obtained through the liquid phase exfoliation treatment of the graphite in the first dispersion medium, so that the key performance of the prepared graphene, such as impermeability, is not damaged. In the process of liquid phase exfoliation, the graphene is modified by the dispersant and the organic acid, so that the graphene has good dispersibility and can be endowed with more active points, which helps to promote the interaction between the graphene and the inorganic corrosion inhibitor and improve the loading rate of the graphene to the corrosion inhibitor. At the same time, under the condition of heat preservation and addition of the surfactant, the graphene realizes good loading effect on the inorganic corrosion inhibitor. The preparation method of the modified graphene provided by the embodiment of the present application can prepare the modified graphene with good corrosion resistance, good dispersibility and poor agglomeration, so that the modified graphene can be used as a stable corrosion-resistant filler. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The flowchart of the preparation method of the modified graphene provided by the embodiment of the present application is shown in the figure;

[0040] Figure 2 In the figure a is the FTIR spectrum of the polyvinyl alcohol, graphite and graphene in Example 1 of the present application, Figure 2 In the figure b is the Raman spectrum of the graphite and graphene in Example 1;

[0041] Figure 3 In the figure a is the FTIR spectrum of the modified graphene, graphene and graphite in Example 1 of the present application, Figure 3 In the figure b is the Raman spectrum of the modified graphene, graphene and graphite in Example 1. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0044] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0045] In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0046] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0047] An embodiment of the present application provides a preparation method of modified graphene, comprising the following steps:

[0048] The dispersant, the organic acid and the graphite are mixed in a first dispersion medium to obtain a first dispersion system, and the first dispersion system is subjected to liquid phase exfoliation treatment to obtain a graphene suspension;

[0049] The unexfoliated graphite in the graphene suspension is removed to obtain a graphene dispersion;

[0050] The graphene dispersion is subjected to solid-liquid separation treatment to obtain a solid-phase graphene raw material;

[0051] The solid-phase graphene raw material, the inorganic corrosion inhibitor and the surfactant are mixed in a second dispersion medium to obtain a second dispersion system, and the second dispersion system is subjected to heat preservation treatment.

[0052] In the preparation method of the modified graphene, the graphene with a relatively complete lattice structure can be obtained through the liquid phase exfoliation treatment of the graphite in the first dispersion medium, so that the key performance of the prepared graphene, such as the permeation resistance, is not damaged. In the process of liquid phase exfoliation, the graphene is modified by the dispersant and the organic acid, so that the graphene has good dispersibility and can be endowed with more active sites, which helps to promote the interaction between the graphene and the inorganic corrosion inhibitor and improve the loading rate of the graphene to the corrosion inhibitor. Meanwhile, under the condition of heat preservation and addition of the surfactant, the graphene can achieve a good loading effect on the inorganic corrosion inhibitor. The preparation method of the modified graphene provided by the application can prepare the modified graphene with good corrosion resistance, good dispersibility and poor agglomeration, so that the modified graphene can be used as a stable corrosion-resistant filler.

[0053] Further, the organic acid can not only improve the loading rate of the inorganic corrosion inhibitor on the graphene, but also form a complex with metal ions in the inorganic corrosion inhibitor as an organic ligand, prevent the hydrolysis or other side reactions of the metal ions in the solution, and play a stable connection role.

[0054] Further, when the modified graphene is used in the corrosion-resistant coating on the surface of the metal substrate, the organic acid and the inorganic corrosion inhibitor can form a protective film on the surface of the metal substrate, and play a synergistic film-forming role. For example, the carboxyl group of citric acid can form a coordination bond with metal ions, and cerium ions of cerium nitrate can also react with active sites on the metal surface. The protective film formed by the joint action of the two can better prevent the contact of corrosive media such as oxygen and water with the metal substrate, thereby enhancing the corrosion resistance.

[0055] Reference Figure 1 As shown in FIG. 1, in some embodiments, the preparation method of the modified graphene comprises the following steps:

[0056] S10: mixing the dispersant, the organic acid and the graphite in the first dispersion medium to obtain a first dispersion system, and performing liquid phase exfoliation treatment on the first dispersion system to obtain a graphene suspension.

[0057] In some embodiments, the dispersant comprises at least one of polyvinyl alcohol, dopamine, sodium polystyrene sulfonate, sodium dodecyl benzene sulfonate and polyvinylpyrrolidone.

[0058] In some embodiments, the organic acid comprises at least one of citric acid, phytic acid, acetic acid and ascorbic acid.

[0059] In some embodiments, the graphite is graphite with a mesh size of 300-1000.

[0060] Optionally, the graphite is 300 mesh, 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh or 1000 mesh graphite, or the graphite can also be graphite in a range between any two of the above mesh.

[0061] In some embodiments, the graphite is flake graphite.

[0062] In some embodiments, the mass ratio of the organic acid to the graphite in the first dispersion system is (1-2):10.

[0063] When the mass ratio of the organic acid to the graphite in the first dispersion system is too low, the modified graphene prepared has poor long-time dispersion performance, and when the mass ratio of the organic acid to the graphite is too high, raw materials are wasted. Optionally, the mass ratio of the organic acid to the graphite in the first dispersion system is 1:10, 1.1:10, 1.2:10, 1.3:10, 1.4:10, 1.5:10, 1.6:10, 1.7:10, 1.8:10, 1.9:10 or 2:10, or the mass ratio of the organic acid to the graphite in the first dispersion system can also be in a range between any two of the above mass ratios.

[0064] In some embodiments, the mass ratio of the dispersant to the graphite in the first dispersion system is (1-2):1.

[0065] When the mass ratio of the dispersant to the graphite in the first dispersion system is too low, the modified graphene prepared has poor long-time dispersion performance, and when the mass ratio of the dispersant to the graphite is too high, raw materials are wasted. Optionally, the mass ratio of the dispersant to the graphite in the first dispersion system is 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, or the mass ratio of the dispersant to the graphite in the first dispersion system can also be in a range between any two of the above mass ratios.

[0066] In some embodiments, the concentration of the organic acid in the first dispersion system is 10 mg / mL-20 mg / mL.

[0067] Optionally, the concentration of the organic acid in the first dispersion system is 10 mg / mL, 11 mg / mL, 12 mg / mL, 13 mg / mL, 14 mg / mL, 15 mg / mL, 16 mg / mL, 17 mg / mL, 18 mg / mL, 19 mg / mL or 20 mg / mL, or the concentration of the organic acid in the first dispersion system can also be in a range between any two of the above concentrations.

[0068] In some embodiments, the concentration of the dispersant in the first dispersion system is 1 mg / mL to 2 mg / mL.

[0069] Optionally, the concentration of the dispersant in the first dispersion system is 1 mg / mL, 1.1 mg / mL, 1.2 mg / mL, 1.3 mg / mL, 1.4 mg / mL, 1.5 mg / mL, 1.6 mg / mL, 1.7 mg / mL, 1.8 mg / mL, 1.9 mg / mL or 2 mg / mL, or the concentration of the dispersant in the first dispersion system can also be within a range between any two of the above concentrations.

[0070] In some embodiments, the concentration of the graphite in the first dispersion system is 10 mg / mL to 20 mg / mL.

[0071] Optionally, the concentration of the graphite in the first dispersion system is 10 mg / mL, 11 mg / mL, 12 mg / mL, 13 mg / mL, 14 mg / mL, 15 mg / mL, 16 mg / mL, 17 mg / mL, 18 mg / mL, 19 mg / mL or 20 mg / mL, or the concentration of the graphite in the first dispersion system can also be within a range between any two of the above concentrations.

[0072] In some embodiments, the dispersant, the organic acid and the graphite are mixed in the first dispersion medium to obtain the first dispersion system, and the liquid phase exfoliation treatment of the first dispersion system comprises the following steps:

[0073] The dispersant and the organic acid are dissolved in deionized water to obtain a first solution;

[0074] The graphite is dispersed in a first organic solvent to obtain a first dispersion liquid;

[0075] The first solution and the first dispersion liquid are mixed, and the mixed solution is subjected to shearing treatment at a rotation speed of 10,000 rpm to 15,000 rpm.

[0076] Through the above liquid phase exfoliation treatment, better exfoliation effect of the graphite can be achieved to obtain the layered graphene.

[0077] In some embodiments, the shearing treatment is performed for 1 h to 2 h.

[0078] Optionally, the rotation speed of the shearing treatment is 10,000 rpm, 11,000 rpm, 12,000 rpm, 13,000 rpm, 14,000 rpm or 15,000 rpm, or the rotation speed of the shearing treatment can also be within a range between any two of the above rotation speeds.

[0079] Optionally, the shearing treatment is performed for 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, or 2 h, or the shearing treatment can be performed for a time within a range between any two of the foregoing times.

[0080] In some embodiments, the first organic solvent includes at least one of ethanol, methanol, acetone, ethylene glycol, isopropyl alcohol, and N-methyl pyrrolidone.

[0081] In some embodiments, the volume ratio of the deionized water to the first organic solvent in the first dispersion is 1: (1-1.5).

[0082] Optionally, the volume ratio of the deionized water to the first organic solvent in the first dispersion is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5, or the volume ratio of the deionized water to the first organic solvent in the first dispersion can be within a range between any two of the foregoing volume ratios.

[0083] In some embodiments, dissolving the dispersant and the organic acid in the deionized water includes the following steps:

[0084] After the dispersant and the organic acid are heated to boiling in the deionized water, the dispersant and the organic acid are continuously stirred at 70°C-95°C for 30 min-120 min to dissolve the dispersant and the organic acid.

[0085] S20: removing the un-exfoliated graphite in the graphene suspension to obtain a graphene dispersion.

[0086] In some embodiments, removing the un-exfoliated graphite in the graphene suspension includes the following steps:

[0087] The graphene suspension is centrifuged at a speed of 500 rpm-1000 rpm to precipitate the un-exfoliated graphite, and a graphene dispersion is obtained.

[0088] Within the foregoing speed range of centrifugation, the un-exfoliated graphite can be precipitated, and the exfoliated graphene can be separated due to its good dispersion effect. It can be understood that, after the graphene suspension is centrifuged as described above, the supernatant obtained is the graphene dispersion.

[0089] In some embodiments, the graphene suspension is centrifuged at a speed of 500 rpm-1000 rpm for 30 min-60 min.

[0090] Optionally, the graphene suspension is centrifuged at a speed of 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, or 1000 rpm, or the graphene suspension can be centrifuged at a speed within a range between any two of the foregoing speeds.

[0091] Optionally, the centrifugation of the graphene suspension at the speed of 500 rpm to 1000 rpm is performed for 30 min, 40 min, 50 min or 60 min, or the centrifugation of the graphene suspension at the speed of 500 rpm to 1000 rpm can also be performed for a time within a range between any two of the above-mentioned times.

[0092] S30: performing a solid-liquid separation treatment on the graphene dispersion to obtain a solid-phase graphene raw material.

[0093] In some embodiments, the solid-liquid separation treatment on the graphene dispersion comprises the following steps:

[0094] The graphene dispersion is centrifuged at a speed of 9000 rpm to 12000 rpm to obtain a graphene precipitate.

[0095] Within the above-mentioned speed range of centrifugation, the graphene in the graphene dispersion can be precipitated to achieve solid-liquid separation, and a solid-phase graphene raw material is obtained.

[0096] In some embodiments, the graphene dispersion is centrifuged at a speed of 9000 rpm to 12000 rpm for 30 min to 60 min.

[0097] Optionally, the graphene dispersion is centrifuged at a speed of 9000 rpm, 10000 rpm, 11000 rpm or 12000 rpm, or the graphene dispersion can also be centrifuged at a speed within a range between any two of the above-mentioned speeds.

[0098] Optionally, the graphene dispersion is centrifuged at a speed of 9000 rpm to 12000 rpm for 30 min, 40 min, 50 min or 60 min, or the graphene dispersion can also be centrifuged at a speed of 9000 rpm to 12000 rpm for a time within a range between any two of the above-mentioned times.

[0099] S40: mixing the solid-phase graphene raw material, the inorganic corrosion inhibitor and the surfactant in a second dispersion medium to obtain a second dispersion system, and performing a heat preservation treatment on the second dispersion system.

[0100] In some embodiments, the inorganic corrosion inhibitor comprises at least one of cerium nitrate, cerium chloride, lanthanum nitrate, lanthanum chloride, lanthanum carbonate, sodium silicate, sodium phosphate and sodium molybdate.

[0101] In some embodiments, the concentration of the inorganic corrosion inhibitor in the second dispersion system is 3 mg / mL to 6 mg / mL.

[0102] Optionally, the concentration of the inorganic corrosion inhibitor in the second dispersion system is 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, 5.5 mg / mL, or 6 mg / mL, or the concentration of the inorganic corrosion inhibitor in the second dispersion system can also be within a range between any two of the above concentrations.

[0103] In some embodiments, the concentration of the solid-phase graphene raw material in the second dispersion system is 0.5 mg / mL to 2 mg / mL.

[0104] Optionally, the concentration of the solid-phase graphene raw material in the second dispersion system is 0.5 mg / mL, 0.75 mg / mL, 1 mg / mL, 1.25 mg / mL, 1.5 mg / mL, 1.75 mg / mL, or 2 mg / mL, or the concentration of the solid-phase graphene raw material in the second dispersion system can also be within a range between any two of the above concentrations.

[0105] Within the above concentration ranges of the inorganic corrosion inhibitor and the solid-phase graphene raw material in the second dispersion system, a good loading effect of graphene on the inorganic corrosion inhibitor can be achieved.

[0106] In some embodiments, the temperature of the heat preservation treatment is 40℃ to 90℃.

[0107] Optionally, the temperature of the heat preservation treatment is 40℃, 50℃, 60℃, 70℃, 80℃, or 90℃, or the temperature of the heat preservation treatment can also be within a range between any two of the above temperatures.

[0108] In some embodiments, the time of the heat preservation treatment is 2h to 3h.

[0109] Optionally, the time of the heat preservation treatment is 2h, 2.2h, 2.4h, 2.6h, 2.8h, or 3h, or the time of the heat preservation treatment can also be within a range between any two of the above times.

[0110] In some embodiments, the surfactant includes at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyldimethylbenzylammonium chloride, and dodecyldimethylbenzylammonium chloride.

[0111] In some embodiments, the concentration of the surfactant in the second dispersion system is 2 mg / mL to 10 mg / mL.

[0112] Optionally, the concentration of the surfactant in the second dispersion system is 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, 6 mg / mL, 7 mg / mL, 8 mg / mL, 9 mg / mL or 10 mg / mL, or the concentration of the surfactant in the second dispersion system can also be within a range between any two of the above concentrations.

[0113] In some embodiments, the second dispersion medium comprises deionized water and a second organic solvent.

[0114] In some embodiments, the second organic solvent comprises at least one of ethanol, methanol, acetone, ethylene glycol, isopropyl alcohol and N-methyl pyrrolidone.

[0115] In some embodiments, the volume ratio of the second organic solvent to the deionized water in the second dispersion medium is 1: (1-1.5).

[0116] Optionally, the volume ratio of the second organic solvent to the deionized water in the second dispersion medium is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5, or the volume ratio of the second organic solvent to the deionized water in the second dispersion medium can also be within a range between any two of the above volume ratios.

[0117] In some embodiments, the mixing of the solid-phase graphene raw material, the inorganic corrosion inhibitor and the surfactant in the second dispersion medium to obtain the second dispersion system comprises the following steps:

[0118] The solid-phase graphene raw material is dispersed in the second dispersion medium by ultrasonic treatment for 10-30 min;

[0119] The inorganic corrosion inhibitor and the surfactant are added to the second dispersion medium.

[0120] In some embodiments, the second dispersion medium is also stirred during the heat preservation process.

[0121] S50: The second dispersion system is centrifuged at a speed of 9000-12000 rpm to obtain a modified graphene precipitate; the modified graphene precipitate is freeze-dried at-40°C to-20°C, and is crushed and sieved to obtain a modified graphene powder.

[0122] In some embodiments, the second dispersion system is centrifuged at a speed of 9000-12000 rpm for 30-60 min.

[0123] In some embodiments, the freeze-drying is performed for 24-36 h.

[0124] Optionally, the centrifugation speed of the second dispersion system is 9000 rpm, 10000 rpm, 11000 rpm or 12000 rpm, or the centrifugation speed of the second dispersion system can also be in the range between any two of the above speeds.

[0125] Optionally, the centrifugation time of the second dispersion system at a speed of 9000 rpm to 12000 rpm is 30 min, 40 min, 50 min or 60 min, or the centrifugation time of the second dispersion system at a speed of 9000 rpm to 12000 rpm can also be in the range between any two of the above times.

[0126] Optionally, the freezing drying temperature is -40°C, -35°C, -30°C, -25°C or -20°C, or the freezing drying temperature can also be in the range between any two of the above temperatures.

[0127] Optionally, the freezing drying time is 24 h, 26 h, 28 h, 30 h, 32 h, 34 h or 36 h, or the freezing drying time can also be in the range between any two of the above times.

[0128] Another embodiment of the present application provides a modified graphene prepared by the preparation method of the modified graphene of any one of the above, comprising a graphene main body, an organic acid and an inorganic corrosion inhibitor; the inorganic corrosion inhibitor is loaded on the graphene main body by the organic acid.

[0129] The modified graphene of the present application can be used as a filler to fill the voids of the anticorrosive coating in the anticorrosive coating, play a physical barrier role of resisting the penetration of corrosive medium, and also can inhibit the occurrence of corrosion by the loaded corrosion inhibitor, realizing the dual effect of physical and chemical protection. At the same time, the above modified graphene is uniformly dispersed and not easy to agglomerate, and can realize a relatively stable anticorrosive filler effect.

[0130] Another embodiment of the present application provides the application of the above modified graphene or the modified graphene prepared by the preparation method of the modified graphene of any one of the above as an anticorrosive filler in an anticorrosive coating.

[0131] The following is a specific example

[0132] Example 1

[0133] Preparation method of modified graphene:

[0134] (1) Disperse 0.6g of polyvinyl alcohol and 6g of citric acid in 200ml of deionized water with magnetic stirring. Heat to boiling and continue magnetic stirring at 90°C for 30min to fully dissolve the polyvinyl alcohol and citric acid. Add 6g of graphite powder (300 mesh) to 300ml of ethanol, add the solution prepared in the above steps, and continue to add deionized water and ethanol to make the total solution volume 600ml and the volume ratio of water to ethanol 1:1. Then shear at 10000rpm for 1h in an ice-water bath to obtain a graphene suspension.

[0135] (2) After centrifuging the graphene suspension at 500 rpm for 60 min, large pieces of graphite that were not fully peeled off were removed by precipitation. The supernatant is the graphene dispersion. After centrifuging the graphene dispersion at 10000 rpm for 30 min, the precipitated graphene raw material was collected.

[0136] (3) Take the above graphene raw material and redisperse it in a mixture of 50 ml of water and ethanol (volume ratio 5:5). Sonicate it at low power for 20 min to redisperse the graphene. Then add 0.15 g of cerium nitrate hydrate and 0.1 g of cetyltrimethylammonium bromide. Then stir it magnetically at 60°C water bath temperature for 3 h.

[0137] (4) After centrifuging the reaction solution in step (3) again at a speed of 10000 rpm for 30 min, cerium salt modified graphene is obtained. The cerium salt modified graphene is freeze-dried at -30°C for 24 h, pulverized and passed through a 300-mesh sieve to obtain modified graphene powder.

[0138] The modified graphene prepared in Example 1 was ultrasonicated for 10 minutes using a 150W ultrasonic cleaner and then dispersed in water or ethanol. The modified graphene exhibited excellent dispersibility and showed no significant precipitation after standing for 2 weeks.

[0139] To investigate the functional groups and surface defects in the graphene powder, Fourier transform infrared (FTIR) and Raman spectroscopy analyses were performed on the graphene in Example 1. Figure 2 As shown in Figure a, Figure 2 Image a shows the FTIR spectra of polyvinyl alcohol, graphite, and graphene. The spectral lines of polyvinyl alcohol and graphene both peak at 3460 cm⁻¹. -1 A distinct -OH stretching vibration absorption peak appeared at the position, much stronger than that of graphite, possibly due to the presence of polyvinyl alcohol on the graphene surface, which greatly increases the number of hydroxyl groups. Figure 2 As shown in b, Figure 2 In the middle, b represents the Raman spectra of graphite and graphene, with both spectral lines ending at approximately 1340 cm⁻¹. -1 ~1350cm -1and a typical D peak and G peak appeared at about 1580 cm -1 -1 The intensity ratio ID / IG of the two peaks can reflect the defect density in the graphene structure. The calculated ID / IG value of the graphene is very low (only 0.08), indicating that the graphene obtained by exfoliation is of high quality, and the defects are planar edge defects rather than in-plane defects. Referring to Figure 3 Figure 3 Fig. 1a is an FTIR spectrum of the modified graphene (Ce-Gr), graphene and graphite powder in Example 1, Figure 3 Fig. 1b is a Raman spectrum of the modified graphene (Ce-Gr), graphene and graphite powder in Example 1. As shown in Figure 3 Fig. 1a, a new absorption peak appears at a position of 1382 cm -1 in the infrared spectrum of Ce-Gr, which is caused by the stretching vibration of Ce-O-Ce and is a characteristic structure of CeO2. Figure 3 As shown in Fig. 1b, the ID / IG value of Ce-Gr does not increase compared with graphite and graphene, indicating that the modification of cerium nitrate does not increase the surface defects of graphene and retains the structural integrity of graphene sheets.

[0140] Example 2

[0141] Preparation method of modified graphene:

[0142] (1) 0.6 g of polyvinyl alcohol and 6 g of phytic acid were dispersed in 200 ml of deionized water by magnetic stirring, heated to boiling and then continued to be stirred at 80°C for 40 min to make the polyvinyl alcohol and phytic acid fully dissolved. 6 g of graphite powder (500 mesh) was added to 300 ml of ethanol, and the solution prepared in the above step was added, and deionized water and ethanol were further added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, then sheared in an ice water bath at a speed of 10000 rpm for 1 h to obtain a graphene suspension;

[0143] (2) The graphene suspension was centrifuged at a speed of 600 rpm for 30 min, and the large pieces of graphite that were not fully exfoliated were removed by precipitation, and the supernatant was the graphene dispersion; the graphene dispersion was centrifuged at a speed of 11000 rpm for 40 min, and the graphene raw material collected from the precipitate;

[0144] (3) The above graphene raw material was dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) again, and ultrasonicated at low power for 30 min to disperse the graphene again; then 0.2 g of cerium chloride and 0.1 g of cetyltrimethylammonium bromide were added, and then stirred at 60°C water bath temperature for 3 h by magnetic stirring;

[0145] ​​(4) The reaction solution in step (3) is centrifuged at a speed of 11000 rpm for 20 min again to obtain cerium salt modified graphene, and the cerium salt modified graphene is freeze-dried at -35 °C for 36 h, crushed and sieved through a 300 mesh sieve to obtain modified graphene powder.

[0146] The modified graphene prepared in Example 2 is ultrasonically cleaned by a 150W ultrasonic cleaning instrument for 10 min, dispersed in water or ethanol, and has excellent dispersibility and no obvious precipitation after standing for 2 weeks.

[0147] Example 3

[0148] Preparation method of modified graphene:

[0149] (1) 0.8 g of polyvinyl alcohol and 8 g of citric acid are dispersed in 200 ml of deionized water by magnetic stirring, heated to boiling, and then magnetic stirring is continued at 95 °C for 50 min to fully dissolve the polyvinyl alcohol and citric acid. 8 g of graphite powder (500 mesh) is added to 300 ml of ethanol, and the solution prepared in the above step is added, and deionized water and ethanol are continuously added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, then sheared at a speed of 11000 rpm in an ice water bath for 2 h to obtain a graphene suspension;

[0150] (2) The graphene suspension is centrifuged at a speed of 500 rpm for 60 min to remove large pieces of graphite that have not been fully exfoliated, and the supernatant is the graphene dispersion; the graphene dispersion is centrifuged at a speed of 10000 rpm for 60 min to collect the graphene raw material precipitated;

[0151] (3) The graphene raw material is dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) again, and ultrasonicated at low power for 40 min to disperse the graphene again; then 0.2 g of cerium chloride and 0.15 g of cetyltrimethylammonium bromide are added, and then magnetic stirring is carried out at a water bath temperature of 60 °C for 2 h;

[0152] (4) The reaction solution in step (3) is centrifuged at a speed of 11000 rpm for 20 min again to obtain cerium salt modified graphene, and the cerium salt modified graphene is freeze-dried at -35 °C for 36 h, crushed and sieved through a 300 mesh sieve to obtain modified graphene powder.

[0153] The modified graphene prepared in Example 3 is ultrasonically cleaned by a 150W ultrasonic cleaning instrument for 10 min, dispersed in water or ethanol, and has excellent dispersibility and no obvious precipitation after standing for 2 weeks.

[0154] Example 4

[0155] Preparation method of modified graphene:

[0156] (1) 1 g of polyvinyl alcohol and 10 g of citric acid were dispersed by magnetic stirring in 200 ml of deionized water, heated to boiling, and then magnetic stirring was continued at 95°C for 50 min to fully dissolve the polyvinyl alcohol and citric acid. 10 g of graphite powder (500 mesh) was added to 300 ml of ethanol, and the solution prepared in the above step was added, and deionized water and ethanol were further added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, and then sheared at 10000 rpm in an ice water bath for 1 h to obtain a graphene suspension;

[0157] (2) The graphene suspension was centrifuged at a speed of 500 rpm for 60 min to remove large pieces of graphite that were not fully exfoliated, and the supernatant was the graphene dispersion; the graphene dispersion was high-speed centrifuged at a speed of 11000 rpm for 50 min to collect the graphene raw material precipitated;

[0158] (3) The graphene raw material was dispersed again in 50 ml of a mixture of water and ethanol (volume ratio 5:5) at low power for 30 min to disperse the graphene again; then 0.25 g of cerium chloride and 0.2 g of cetyltrimethylammonium bromide were added, and then magnetic stirring was carried out at a water bath temperature of 60°C for 2 h;

[0159] (4) The reaction solution in step (3) was high-speed centrifuged again at a speed of 10000 rpm for 30 min to obtain cerium salt modified graphene, which was freeze-dried at -35°C for 24 h, crushed and passed through a 300 mesh sieve to obtain modified graphene powder.

[0160] The modified graphene prepared in Example 4 was dispersed in water or ethanol by ultrasonic cleaning instrument of 150W for 10 min, and the modified graphene had excellent dispersibility and no obvious precipitation after standing for 2 weeks.

[0161] Example 5

[0162] Preparation method of modified graphene:

[0163] (1) 0.8 g of polyvinyl alcohol and 8 g of citric acid were dispersed by magnetic stirring in 200 ml of deionized water, heated to boiling, and then magnetic stirring was continued at 85°C for 30 min to fully dissolve the polyvinyl alcohol and citric acid. 8 g of graphite powder (300 mesh) was added to 300 ml of ethanol, and the solution prepared in the above step was added, and deionized water and ethanol were further added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, and then sheared at 10000 rpm in an ice water bath for 2 h to obtain a graphene suspension;

[0164] (2) The graphene suspension liquid is centrifuged at a speed of 500 rpm for 45 min, and the precipitate of large pieces of graphite which are not sufficiently peeled off is removed, and the supernatant is graphene dispersion liquid; the graphene dispersion liquid is high-speed centrifuged at a speed of 10000 rpm for 45 min, and the precipitated graphene raw material is collected;

[0165] (3) The graphene raw material is taken and dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) again, and is ultrasonically dispersed at low power for 20 min, so that the graphene is dispersed again; then 0.15 g of cerium nitrate hydrate and 0.1 g of hexadecyl trimethyl ammonium bromide are added, and then magnetic stirring is carried out at a water bath temperature of 50 °C for 3 h;

[0166] (4) The reaction liquid in step (3) is high-speed centrifuged at a speed of 10000 rpm for 30 min again to obtain cerium salt modified graphene, and the cerium salt modified graphene is freeze-dried at -30 °C for 24 h, is crushed and passed through a 300 mesh sieve to obtain modified graphene powder.

[0167] The modified graphene prepared in Example 5 is ultrasonically cleaned by a 150 W ultrasonic cleaning instrument for 10 min, and is dispersed in water or ethanol. The modified graphene has excellent dispersibility, and no obvious precipitation is observed after standing for 2 weeks.

[0168] Example 6

[0169] Preparation method of modified graphene:

[0170] (1) 0.1 g of polyvinyl alcohol and 1 g of citric acid are dispersed in 200 ml of deionized water by magnetic stirring, heated to boiling, and then magnetic stirring is continued at 90 °C for 30 min to fully dissolve the polyvinyl alcohol and citric acid. 15 g of graphite powder (300 mesh) is added to 300 ml of ethanol, and the solution prepared in the above step is added, and deionized water and ethanol are continuously added, so that the total solution volume is 600 ml and the volume ratio of water and ethanol is 1:1, and then shearing is carried out at a speed of 10000 rpm in an ice water bath for 1 h to obtain a graphene suspension liquid;

[0171] (2) The graphene suspension liquid is centrifuged at a speed of 500 rpm for 60 min, and the precipitate of large pieces of graphite which are not sufficiently peeled off is removed, and the supernatant is graphene dispersion liquid; the graphene dispersion liquid is high-speed centrifuged at a speed of 10000 rpm for 30 min, and the precipitated graphene raw material is collected;

[0172] (3) The graphene raw material is taken and dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) again, and is ultrasonically dispersed at low power for 20 min, so that the graphene is dispersed again; then 0.15 g of cerium nitrate hydrate and 0.1 g of hexadecyl trimethyl ammonium bromide are added, and then magnetic stirring is carried out at a water bath temperature of 70 °C for 3 h;

[0173] (4) The reaction solution in step (3) was centrifuged at 10000 rpm for 30 min to obtain cerium salt modified graphene. The cerium salt modified graphene was freeze-dried at -30 °C for 24 h, crushed and passed through a 300 mesh sieve to obtain modified graphene powder.

[0174] The modified graphene prepared in Example 6 was dispersed in water or ethanol by ultrasonic cleaning instrument of 150 W for 10 min. The modified graphene had good dispersibility, but precipitated after standing for 5 days.

[0175] Example 7

[0176] Preparation method of modified graphene:

[0177] (1) 0.2 g of polyvinyl alcohol and 2 g of citric acid were dispersed in 200 ml of deionized water by magnetic stirring, heated to boiling, and then magnetic stirring was continued at 90 °C for 30 min to fully dissolve the polyvinyl alcohol and citric acid. 2 g of graphite powder (300 mesh) was added to 300 ml of ethanol, and the above prepared solution was added, and deionized water and ethanol were continuously added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, then sheared at 10000 rpm in an ice water bath for 1 h to obtain a graphene suspension;

[0178] (2) The graphene suspension was centrifuged at 500 rpm for 60 min to remove large pieces of graphite that were not fully exfoliated, and the supernatant was the graphene dispersion. The graphene dispersion was centrifuged at 10000 rpm for 30 min to collect the graphene raw material precipitated;

[0179] (3) The above graphene raw material was dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) again, and ultrasonic was applied at low power for 20 min to disperse the graphene again. Then 0.15 g of cerium nitrate hydrate and 0.1 g of cetyltrimethylammonium bromide were added, and then magnetic stirring was carried out at 65 °C water bath temperature for 3 h;

[0180] (4) The reaction solution in step (3) was centrifuged at 10000 rpm for 30 min to obtain cerium salt modified graphene. The cerium salt modified graphene was freeze-dried at -30 °C for 24 h, crushed and passed through a 300 mesh sieve to obtain modified graphene powder.

[0181] The modified graphene prepared in Example 7 was dispersed in water or ethanol by ultrasonic cleaning instrument of 150 W for 10 min. The modified graphene had good dispersibility, but precipitated after standing for 7 days.

[0182] Comparative Example 1

[0183] The difference between Comparative Example 1 and the preparation method of the modified graphene in Example 1 is that no dispersant and organic acid are used to modify the graphene in Comparative Example 1.

[0184] The preparation method of the modified graphene:

[0185] (1) 6 g of graphite powder (300 mesh) was added to 300 ml of ethanol, and the solution prepared in the above step was added, and deionized water and ethanol were continuously added, so that the total solution volume was 600 ml and the volume ratio of water and ethanol was 1:1, and then shearing was carried out at a speed of 10000 rpm in an ice water bath for 1 h to obtain a graphene suspension;

[0186] (2) The graphene suspension was centrifuged at a speed of 500 rpm for 60 min, and the large pieces of graphite that were not fully exfoliated were removed by precipitation, and the supernatant was the graphene dispersion; the graphene dispersion was high-speed centrifuged at a speed of 10000 rpm for 30 min, and the graphene raw material precipitated was collected;

[0187] (3) The above graphene raw material was dispersed again in 50 ml of a mixture of water and ethanol (volume ratio 5:5) at low power ultrasonic for 20 min to disperse the graphene again; then 0.15 g of cerium nitrate hydrate and 0.1 g of cetyltrimethylammonium bromide were added, and then magnetic stirring was carried out at a water bath temperature of 60°C for 3 h;

[0188] (4) The reaction solution in step (3) was high-speed centrifuged again at a speed of 10000 rpm for 30 min to obtain cerium salt modified graphene, which was freeze-dried at -30°C for 24 h, crushed and passed through a 300 mesh sieve to obtain modified graphene powder.

[0189] The modified graphene prepared in Example 1 was ultrasonically cleaned by a 150W ultrasonic cleaner for 10 min and dispersed in water or ethanol. The dispersibility of the modified graphene was poor, and a uniform dispersion system could not be formed, and there were particulate substances in the liquid.

[0190] Comparative Example 2

[0191] The difference between Comparative Example 2 and the preparation method of the modified graphene in Example 1 is that no surfactant is added in step (3) in Comparative Example 2.

[0192] (1) 0.6 g of polyvinyl alcohol and 6 g of citric acid were dispersed in 200 ml of deionized water by magnetic stirring, heated to boiling, and then continued to be stirred at 90 °C for 30 min to fully dissolve the polyvinyl alcohol and citric acid. 6 g of graphite powder (300 mesh) was added to 300 ml of ethanol, and the solution prepared in the above step was added, and deionized water and ethanol were continuously added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, and then sheared at 10000 rpm in an ice water bath for 1 h to obtain a graphene suspension;

[0193] (2) The graphene suspension was centrifuged at a speed of 500 rpm for 60 min, and the precipitate was removed to remove the large pieces of graphite that were not fully exfoliated. The supernatant was the graphene dispersion. The graphene dispersion was centrifuged at a speed of 10000 rpm for 30 min, and the graphene raw material precipitated was collected;

[0194] (3) The graphene raw material was dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) at low power for 20 min to re-disperse the graphene. Then 0.15 g of cerium nitrate hydrate was added, and then the mixture was stirred at 60 °C for 3 h;

[0195] (4) The reaction solution in step (3) was centrifuged at a speed of 10000 rpm for 30 min to obtain cerium salt modified graphene. The cerium salt modified graphene was freeze-dried at -30 °C for 24 h, crushed and passed through a 300 mesh sieve to obtain modified graphene powder.

[0196] The modified graphene prepared in Comparative Example 2 was dispersed in water or ethanol by ultrasonic cleaning instrument at 150 W for 10 min. The dispersion effect of the modified graphene was poor, and the liquid had a obvious particle feeling. The modified graphene precipitated after standing for half an hour.

[0197] Comparative Example 3

[0198] The difference between Comparative Example 3 and Example 2 is that the mixture in step (3) of Comparative Example 3 is not subjected to heat treatment.

[0199] (1) 0.6 g of polyvinyl alcohol and 6 g of citric acid were dispersed in 200 ml of deionized water by magnetic stirring, heated to boiling, and then continued to be stirred at 90 °C for 30 min to fully dissolve the polyvinyl alcohol and citric acid. 6 g of graphite powder (300 mesh) was added to 300 ml of ethanol, and the solution prepared in the above step was added, and deionized water and ethanol were continuously added to make the total solution volume 600 ml and the volume ratio of water and ethanol 1:1, and then sheared at 10000 rpm in an ice water bath for 1 h to obtain a graphene suspension;

[0200] (2) The graphene suspension liquid is centrifuged at a speed of 600 rpm for 30 min, and the precipitate is removed to obtain graphene dispersion liquid; the graphene dispersion liquid is centrifuged at a speed of 11000 rpm for 40 min, and the precipitate is collected to obtain graphene raw material;

[0201] (3) The graphene raw material is dispersed in 50 ml of a mixture of water and ethanol (volume ratio 5:5) again, and is ultrasonically treated at a low power for 30 min to make the graphene re-disperse; then 0.2 g of cerium chloride and 0.1 g of hexadecyl trimethyl ammonium bromide are added, and the mixture is stirred magnetically at room temperature for 2 h;

[0202] (4) The reaction liquid in step (3) is centrifuged at a speed of 10000 rpm for 20 min to obtain cerium salt modified graphene, which is freeze-dried at -40 °C for 24 h, is pulverized and is passed through a 300 mesh sieve to obtain modified graphene powder.

[0203] The modified graphene prepared in Comparative Example 3 is dispersed in water or ethanol by ultrasonic cleaning instrument at 150 W for 10 min, and the dispersion effect of the modified graphene is poor, the liquid has obvious particle feeling, and the liquid is precipitated after standing for half an hour.

[0204] The stability results of the modified graphene in Examples 1 to 7 and Comparative Examples 1 to 3 are shown in the following table:

[0205]

[0206] Comparative Example 1 and Comparative Example 1, the graphite powder is not modified by dispersant and organic acid, and is directly subjected to shearing and peeling, and the functional groups on the surface of the graphene are less, and the dispersion is poor. Therefore, it can be seen that the modified graphene with good dispersion can be prepared by first modifying the dispersant and the organic acid in the present application, to provide a suitable reaction site for the modification process.

[0207] Comparative Example 1 and Comparative Examples 2 and 3, it can be seen that the graphene obtained by liquid phase peeling under the conditions of adding a surfactant and heating can further react with the corrosion inhibitor efficiently and selectively, so that the corrosion inhibitor is selectively grafted with the graphene to prepare modified graphene loaded with the corrosion inhibitor and having good dispersion performance. When the activity of the corrosion inhibitor is reduced under neutral or room temperature conditions, the corrosion inhibitor cannot fully react with the graphene, and thus the dispersion performance of the modified graphene obtained is poor.

[0208] From Comparative Example 1 to Example 7, it can be seen that the dispersing performance of the modified graphene prepared in Example 6 and Example 7 is slightly worse than that of the modified graphene prepared in Example 1 to Example 5, and the prepared modified graphene is prone to agglomeration after long-time standing when the content of graphite is too high, i.e. the content of dispersing agent and organic acid is too low.

[0209] The technical features of the above-described examples can be combined in any manner. In order to make the description concise, all possible combinations of the technical features in the above-described examples are not described, but as long as the combinations of the technical features do not exist in contradiction, they should be considered as falling within the scope of the present disclosure.

[0210] The above-described examples only express several embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A method for preparing modified graphene, characterized by, The method comprises the following steps: mixing a dispersant, an organic acid and graphite in a first dispersion medium to obtain a first dispersion system, performing liquid phase exfoliation treatment on the first dispersion system to obtain a graphene suspension; the dispersant comprises at least one of polyvinyl alcohol, dopamine, sodium polystyrene sulfonate, sodium dodecyl benzene sulfonate and polyvinylpyrrolidone; the organic acid comprises at least one of citric acid, phytic acid, acetic acid and ascorbic acid; in the first dispersion system, the concentration of the organic acid is 10 mg / mL to 20 mg / mL, the concentration of the dispersant is 1 mg / mL to 2 mg / mL, and the concentration of the graphite is 10 mg / mL to 20 mg / mL; removing unexfoliated graphite in the graphene suspension to obtain a graphene dispersion; performing solid-liquid separation treatment on the graphene dispersion to obtain a solid-phase graphene raw material; mixing the solid-phase graphene raw material, an inorganic corrosion inhibitor and a surfactant in a second dispersion medium to obtain a second dispersion system, and performing heat preservation treatment on the second dispersion system; the inorganic corrosion inhibitor comprises at least one of cerium nitrate, cerium chloride, lanthanum nitrate, lanthanum chloride, lanthanum carbonate, sodium silicate, sodium phosphate and sodium molybdate; the temperature of the heat preservation treatment is 40 DEG C to 90 DEG C; and the time of the heat preservation treatment is 2 h to 3 h.

2. The method of claim 1, wherein the modified graphene is prepared by the steps of: The graphite is graphite with a mesh number of 300 to 1000. ​ 3. The method for preparing modified graphene according to claim 1, characterized in that, In the second dispersion system, the concentration of the solid-phase graphene raw material is 0.5 mg / mL to 2 mg / mL; and / or, In the second dispersion system, the concentration of the inorganic corrosion inhibitor is 3 mg / mL to 6 mg / mL; and / or, The surfactant comprises at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyl dimethyl benzyl ammonium chloride and dodecyl dimethyl benzyl ammonium chloride; and / or, In the second dispersion system, the concentration of the surfactant is 2 mg / mL to 10 mg / mL.

4. The method for preparing modified graphene according to claim 1, characterized in that, The method comprises the following steps: dissolving the dispersant and the organic acid in deionized water to obtain a first solution; dispersing the graphite in a first organic solvent to obtain a first dispersion; mixing the first solution and the first dispersion, and performing shearing treatment on the mixed solution at a rotating speed of 10,000 rpm to 15,000 rpm.

5. The method for preparing modified graphene according to claim 1, characterized in that, The method for removing unexfoliated graphite in the graphene suspension comprises the following steps: centrifuging the graphene suspension at a rotating speed of 500 rpm to 1,000 rpm to precipitate the unexfoliated graphite, and obtaining the graphene dispersion.

6. The method for preparing modified graphene according to claim 1, characterized in that, The method for performing solid-liquid separation treatment on the graphene dispersion comprises the following steps: centrifuging the graphene dispersion at a rotating speed of 9,000 rpm to 12,000 rpm to obtain graphene precipitate.

7. The method for preparing modified graphene according to any one of claims 1 to 6, characterized in that, After the heat preservation treatment on the second dispersion system, the method further comprises the following steps: centrifuging the second dispersion system at a rotating speed of 9,000 rpm to 12,000 rpm to obtain modified graphene precipitate; The modified graphene is freeze-dried at -40°C to -20°C, and is crushed and sieved to obtain modified graphene powder.

8. A modified graphene, characterized by, The modified graphene is prepared by the preparation method of any one of claims 1-7, and comprises a graphene main body, an organic acid and an inorganic corrosion inhibitor; the inorganic corrosion inhibitor is loaded on the graphene main body by the organic acid.

9. Use of the modified graphene according to claim 8 as a corrosion-resistant filler in a corrosion-resistant coating.

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