A graphene oxide dispersion liquid, a graphene oxide-modified cement mortar, and a preparation method and application thereof

Abstract

The present invention belongs to the technical field of building materials, and relates to a graphene oxide dispersion liquid, a cement mortar modified by graphene oxide, and a preparation method and application thereof. The preparation method of the graphene oxide dispersion liquid includes: S1. performing a first modification reaction on graphene oxide and a sulfonic acid group source compound in a first solution to obtain sulfonic acid group-modified graphene oxide; S2. performing a second modification reaction on the sulfonic acid group-modified graphene oxide and tea polyphenols in a second solution to obtain a graphene oxide dispersion liquid. The key of the present invention lies in that through the synergistic modification effect of sulfonic acid groups and tea polyphenols on graphene oxide, the dispersibility of graphene oxide in a high-calcium and high-alkaline environment of cement mortar can be improved. When the obtained modified graphene oxide dispersion liquid is added to cement mortar, it can not only improve the fluidity of the cement mortar, but also improve the flexural strength and compressive strength of the cement mortar.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a graphene oxide dispersion liquid, a cement mortar modified with graphene oxide, and a preparation method and application thereof. Background Art

[0002] Concrete is considered the most widely used building material globally. With the increasing demand for more complex and durable concrete structures, higher requirements are also put forward for the performance of concrete. However, traditional concrete types often exhibit performance defects such as cracking, reduced durability, and low ductility. Introducing nanomaterials to improve the concrete microstructure is one of the most effective methods to reduce concrete cracks, pores, and defects.

[0003] As a derivative of graphene, graphene oxide has a two-dimensional single atomic layer structure, with ultra-high strength and flexibility, and at the same time has a high specific surface area. It is recognized as the most potential candidate to improve the performance of concrete. However, due to the presence of oxygen-containing functional group carboxyl, it can 2+ undergo a complexation reaction with Ca in the cement environment, causing graphene oxide to agglomerate and precipitate. At the same time, the addition of graphene oxide will reduce the fluidity of the cement mortar. The existence of these problems is not conducive to improving the overall performance of the cement mortar. Summary of the Invention

[0004] The purpose of the present invention is to provide a graphene oxide dispersion liquid, a cement mortar modified with graphene oxide, and a preparation method and application thereof, aiming at the defects in the prior art that graphene oxide will reduce the fluidity of the cement mortar and has limited improvement effect on the flexural strength and compressive strength of the cement mortar.

[0005] In the first aspect, the present invention provides a preparation method of a graphene oxide dispersion liquid, and the preparation method includes: S1. Performing a first modification reaction on graphene oxide and a sulfonic acid group source compound in a first solution to obtain sulfonic acid group-modified graphene oxide; S2. Performing a second modification reaction on the sulfonic acid group-modified graphene oxide obtained in step S1 and tea polyphenols in a second solution to obtain the graphene oxide dispersion liquid.

[0006] In some specific embodiments, in step S1, the sulfonic acid group source compound is used in the form of a sulfonic acid group source compound solution.

[0007] In some specific embodiments, in step S1, the dosage of the graphene oxide is 1-5 parts by weight, and the dosage of the sulfonic acid group source compound solution is 150-250 parts by weight.

[0008] In some specific embodiments, in step S2, the dosage of the tea polyphenols is 0.3 to 0.7 parts by weight, and the dosage of the second solution is 200 to 400 parts by weight.

[0009] In some specific embodiments, the first modification reaction is a reaction carried out by stirring graphene oxide, a sulfonic acid group source compound, and a first solution.

[0010] In some specific embodiments, the stirring time is 20 to 28 h.

[0011] In some specific embodiments, the second modification reaction is a reaction carried out by stirring the sulfonic acid group-modified graphene oxide obtained in step S1, tea polyphenols, and a second solution.

[0012] In some specific embodiments, the stirring speed is 4000 to 6000 rpm, and the stirring time is 1 to 3 h.

[0013] In some specific embodiments, the sulfonic acid group source compound is selected from at least one of sulfuric acid, sulfurous acid, sodium lignosulfonate, and sodium dodecylbenzenesulfonate.

[0014] Second, the present invention provides a graphene oxide dispersion liquid prepared by the above method.

[0015] Third, the present invention provides a graphene oxide-modified cement mortar, and the cement mortar contains the above graphene oxide dispersion liquid, a water reducing agent, water, cement, sand, and optionally additives and auxiliary materials.

[0016] In some specific embodiments, the content of the graphene oxide dispersion liquid is 15 to 90 parts by weight, the content of the water reducing agent is 3 to 7 parts by weight, the content of pure water is 150 to 250 parts by weight, the content of cement is 300 to 500 parts by weight, the content of sand is 1000 to 1500 parts by weight, the content of additives is 0.6 to 2.5 parts by weight, and the content of auxiliary materials is 1.2 to 3.0 parts by weight.

[0017] Fourth, the present invention also provides the application of the above graphene oxide dispersion liquid and / or the above graphene oxide-modified cement mortar in the field of building materials.

[0018] The key of the present invention lies in that through the synergistic modification effect of sulfonic acid groups and tea polyphenols on graphene oxide, the dispersibility of graphene oxide can be improved, especially the dispersibility of graphene oxide in the high-calcium and high-alkaline environment of cement mortar. When the obtained modified graphene oxide dispersion liquid is added to cement mortar, it can not only improve the fluidity of cement mortar, but also improve the flexural strength and compressive strength of cement mortar. Detailed Embodiments

[0019] The preparation method of the graphene oxide dispersion provided by the present invention includes: S1. Performing a first modification reaction on graphene oxide and a sulfonic acid group source compound in a first solution to obtain sulfonic acid group-modified graphene oxide; S2. Performing a second modification reaction on the sulfonic acid group-modified graphene oxide obtained in step S1 and tea polyphenols in a second solution to obtain the graphene oxide dispersion.

[0020] In the present invention, in step S1, the sulfonic acid group source compound is a type of compound that can provide a source of sulfonic acid groups for graphene oxide. The reaction method can be to add graphene oxide and the sulfonic acid group source compound to the first solution simultaneously for the first modification reaction, or to first mix graphene oxide and the first solution evenly and then add the sulfonic acid group source compound for the first modification reaction, or to first mix the sulfonic acid group source compound and the first solution to obtain a sulfonic acid group source compound solution and then add graphene oxide for the first modification reaction. The third reaction method is preferably adopted, that is, the sulfonic acid group source compound is preferably used in the form of a sulfonic acid group source compound solution. Among them, the dosage of the graphene oxide is preferably 1 to 5 parts by weight, such as 1, 2, 3, 4, 5 parts by weight or any value between them; the dosage of the sulfonic acid group source compound solution is preferably 150 to 250 parts by weight, such as 150, 180, 200, 220, 250 parts by weight or any value between them. The first solution is preferably water. Controlling the dosages of the graphene oxide and the sulfonic acid group source compound solution within the above preferred ranges is more conducive to improving the fluidity, flexural strength, and bending strength of the cement mortar when the modified graphene oxide is applied to the cement mortar.

[0021] In the present invention, the sulfonic acid group source compound solution can be a solution obtained by mixing a sulfonic acid group source compound and a solvent capable of dissolving the sulfonic acid group source compound. The present invention does not specifically limit the type of the sulfonic acid group source compound, and any compound containing a sulfonic acid group is acceptable. Specific examples thereof include, but are not limited to, at least one of sulfuric acid, sulfurous acid, sodium lignosulfonate, and sodium dodecylbenzenesulfonate, and sulfuric acid is preferred. The present invention does not specifically limit the type of the solvent, and water is preferred. The present invention does not specifically limit the dosage of the sulfonic acid group source compound or the concentration of the sulfonic acid group source compound in the sulfonic acid group source compound solution. That is, when using different types of sulfonic acid group source compounds, sulfonic acid group source compound solutions with different concentrations can be adopted, as long as the sulfonic acid groups can be sufficiently grafted onto graphene oxide to obtain sulfonic acid group-modified graphene oxide. When the sulfonic acid group source compound used is sulfuric acid, the mass percentage of sulfuric acid in the sulfonic acid group source compound solution, i.e., the sulfuric acid solution, is preferably 70-98 wt%, such as 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 95 wt%, 98 wt% or any value between them. When the sulfonic acid group source compound used is sodium dodecylbenzenesulfonate, the mass percentage of sodium dodecylbenzenesulfonate in the sulfonic acid group source compound solution, i.e., the sodium dodecylbenzenesulfonate solution, is preferably 1-5 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or any value between them.

[0022] In the present invention, in step S2, the dosage of the tea polyphenol is preferably 0.3-0.7 parts by weight, such as 0.3, 0.4, 0.5, 0.6, 0.7 parts by weight or any value between them; the dosage of the pure water is preferably 200-400 parts by weight, such as 200, 250, 300, 350, 400 parts by weight or any value between them. Controlling the dosage of the tea polyphenol within the above preferred range is more conducive to realizing the dispersion of graphene oxide (GO) and preventing GO from agglomerating.

[0023] In the present invention, the purpose of the first modification reaction is to graft the sulfonic acid groups provided by the sulfonic acid group source compound onto graphene oxide. Specifically, it can be a modification reaction of 1-5 parts by weight of graphene oxide and 150-250 parts by weight of the sulfonic acid group source compound solution under stirring. After the stirring ends, it is washed with pure water, filtered by suction, and dried to obtain sulfonic acid group-modified graphene oxide powder. Among them, the stirring time is not specifically limited and can be a conventional choice in the art. It is preferably 20-28 h, such as 20 h, 22 h, 24 h, 26 h, 28 h or any value between them. At this time, it is more conducive to uniformly modifying the sulfonic acid groups onto graphene oxide and will not damage the original structure of graphene oxide.

[0024] In the present invention, the graphene oxide can be prepared by various methods in the prior art or obtained by commercial purchase.

[0025] In the present invention, the purpose of the second modification reaction is to graft tea polyphenols onto the sulfonic acid group-modified graphene oxide. Specifically, it can be a modification reaction in which the sulfonic acid group-modified graphene oxide obtained in step S1, 0.5-1.0 parts by weight of tea polyphenols, and 200-400 parts by weight of pure water are subjected to under stirring. Among them, the stirring speed is preferably 4000-6000 rpm, such as 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm or any value between them. At this time, it is more conducive to uniformly and efficiently modifying tea polyphenols onto the sulfonic acid group-modified graphene oxide; the stirring time is not specifically limited and can be a conventional choice in the art, preferably 1-3 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h or any value between them. Preferably, step S2 can be: first, the sulfonic acid group-modified graphene oxide obtained in step S1 is mixed with 200-400 parts by weight of pure water and ultrasonically dispersed, and then 0.5-1.0 parts by weight of tea polyphenols are added, and the second modification reaction is carried out under high-speed stirring at 4000-6000 rpm to obtain a graphene oxide dispersion.

[0026] The graphene oxide-modified cement mortar provided by the present invention comprises a graphene oxide dispersion, a water reducing agent, water, cement, sand and soil, and optionally additives and auxiliary materials, which are prepared by the above method. Among them, the content of the graphene oxide dispersion is preferably 15-90 parts by weight, such as 15, 20, 30, 45, 60, 75, 80, 90 parts by weight or any value between them. The content of the water reducing agent is preferably 3-7 parts by weight, such as 3, 4, 5, 6, 7 parts by weight or any value between them. The content of the pure water is preferably 150-250 parts by weight, such as 150, 160, 175, 180, 190, 205, 220, 235, 250 parts by weight or any value between them. The content of the cement is preferably 300-500 parts by weight, such as 300, 350, 400, 450, 500 parts by weight or any value between them. The content of the sand and soil is preferably 1000-1500 parts by weight, such as 1000, 1100, 1200, 1300, 1400, 1500 parts by weight or any value between them. The water reducing agent can be various existing water reducing agents, preferably carboxylic acid-based water reducing agents. The additives and auxiliary materials can be various materials used in the prior art for preparing cement mortar, and the present invention does not specifically limit their types.

[0027] The graphene oxide modified cement mortar provided by the present invention is obtained by mixing the graphene oxide dispersion liquid prepared by the above method, a water reducing agent, water, cement, sand and soil, and optionally additives and auxiliary materials. The mixing order and method of the above raw materials can be determined according to conventional selection. Preferably, the mixing order and method of the above raw materials can be: first, disperse the graphene oxide dispersion liquid prepared by the above method into water to obtain mixture I, then premix cement and sand and soil to obtain mixture II, and then mix and stir mixture I, the water reducing agent, mixture II, and optionally additives and auxiliary materials, and then the graphene oxide modified cement mortar can be obtained.

[0028] The present invention will be described in detail below through specific examples.

[0029] In the following preparation examples, examples and comparative examples, the parts of the raw materials involved all refer to parts by weight.

[0030] Sources of raw materials involved in the following preparation examples and examples: Graphene oxide powder is prepared by the Hummer method, scale graphite is oxidized, and then graphene oxide is collected by suction filtration, and then dialysis is carried out. When the pH of the solution is neutral, graphene oxide is collected for use; The water reducing agent is purchased from Shanghai Chenqi Chemical Technology Co., Ltd., and the brand is 540P.

[0031] Preparation Example 1 Preparation of Graphene Oxide Dispersion Liquid

[0032] S1. Add 2 parts of graphene oxide powder to a 500 mL flask, and then slowly pour in 200 parts of concentrated sulfuric acid (mass percentage is 98 wt%), stir at room temperature for 24 h. After stirring, add 1000 parts of pure water for washing, then carry out suction filtration and drying to obtain sulfonic acid group modified graphene oxide powder;

[0033] S2. Take the sulfonic acid group modified graphene oxide powder prepared in step S1 and add it to a 500 mL beaker, add 300 parts of pure water, then place it in an ultrasonic machine for ultrasonic treatment for 2 h. Then add 0.5 part of tea polyphenol to the ultrasonicated solution and carry out high-speed shear stirring at a rotation speed of 5000 rpm for 2 h to obtain the graphene oxide dispersion liquid.

[0034] Preparation Example 2 Preparation of Graphene Oxide Dispersion Liquid

[0035] S1. Add 5 parts of graphene oxide powder to a 500 mL flask, and then slowly pour in 250 parts of concentrated sulfuric acid (mass percentage is 98 wt%), stir at room temperature for 24 h. After stirring, add 1000 parts of pure water for washing, then carry out suction filtration and drying to obtain sulfonic acid group modified graphene oxide powder;

[0036] S2. Take the sulfonic acid group-modified graphene oxide powder prepared in step S1 and add it to a 500 mL beaker. After adding 300 parts of pure water, place it in an ultrasonic machine for ultrasonic treatment for 2 h. Then, add 0.7 part of tea polyphenol to the ultrasonically treated solution and carry out high-speed shear stirring at a rotation speed of 5000 rpm for 2 h to obtain a graphene oxide dispersion.

[0037] Preparation of graphene oxide dispersion in Preparation Example 3

[0038] S1. Add 2 parts of graphene oxide powder to a 500 mL flask, and then slowly pour in 150 parts of concentrated sulfuric acid (mass percentage is 98 wt%). Stir at room temperature for 24 h. After the stirring is completed, add 1000 parts of pure water for washing, and then carry out suction filtration and drying to obtain sulfonic acid group-modified graphene oxide powder;

[0039] S2. Take the sulfonic acid group-modified graphene oxide powder prepared in step S1 and add it to a 500 mL beaker. After adding 300 parts of pure water, place it in an ultrasonic machine for ultrasonic treatment for 2 h. Then, add 0.3 part of tea polyphenol to the ultrasonically treated solution and carry out high-speed shear stirring at a rotation speed of 5000 rpm for 2 h to obtain a graphene oxide dispersion.

[0040] Preparation of graphene oxide dispersion in Preparation Example 4

[0041] Prepare the graphene oxide dispersion according to the method of Preparation Example 1, except that the same amount of sodium dodecylbenzenesulfonate solution (mass percentage is 3 wt%) is used instead of concentrated sulfuric acid (mass percentage is 98 wt%), and the other conditions are the same as those in Preparation Example 1, and thus the graphene oxide dispersion is prepared.

[0042] Preparation of reference graphene oxide dispersion in Comparative Preparation Example 1

[0043] Add 2 parts of graphene oxide powder to a 500 mL flask, add 300 parts of pure water, place it in an ultrasonic machine for ultrasonic treatment for 2 h, and then carry out high-speed shear stirring at a rotation speed of 5000 rpm for 2 h to obtain a reference graphene oxide dispersion.

[0044] Preparation of reference graphene oxide dispersion in Comparative Preparation Example 2

[0045] S1. Add 2 parts of graphene oxide powder to a 500 mL flask, and then slowly pour in 200 parts of concentrated sulfuric acid (mass percentage is 98 wt%). Stir at room temperature for 24 h. After the stirring is completed, add 1000 parts of pure water for washing, and then carry out suction filtration and drying to obtain sulfonic acid group-modified graphene oxide powder;

[0046] S2. Take the sulfonic acid group-modified graphene oxide powder prepared in step S1 and add it to a 500 mL beaker. After adding 300 parts of pure water, place it in an ultrasonic machine for ultrasonic treatment for 2 h to obtain a reference graphene oxide dispersion liquid.

[0047] Preparation of the reference graphene oxide dispersion liquid in Comparative Preparation Example 3

[0048] Take 2 parts of graphene oxide powder and add it to a 500 mL beaker. After adding 300 parts of pure water, place it in an ultrasonic machine for ultrasonic treatment for 2 h. Subsequently, add 0.5 part of tea polyphenol to the ultrasonically treated solution and perform high-speed shear stirring at a rotation speed of 5000 rpm for 2 h to obtain a reference graphene oxide dispersion liquid.

[0049] Example 1 Graphene Oxide-Modified Cement Mortar

[0050] Ultrasonically disperse 15 parts of the graphene oxide dispersion liquid in Preparation Example 1 in 250 parts of pure water for 0.2 h. Then add 5 parts of a water reducing agent to the dispersed solution, and then pour this mixture into a mixture of 400 parts of cement and 1200 parts of river sand, and stir for 2 min to obtain the finished cement mortar.

[0051] Example 2 Graphene Oxide-Modified Cement Mortar

[0052] Ultrasonically disperse 30 parts of the graphene oxide dispersion liquid in Preparation Example 1 in 235 parts of pure water for 0.2 h. Then add 5 parts of a water reducing agent to the dispersed solution, and then pour this mixture into a mixture of 400 parts of cement and 1200 parts of river sand, and stir for 2 min to obtain the finished cement mortar.

[0053] Example 3 Graphene Oxide-Modified Cement Mortar

[0054] Ultrasonically disperse 45 parts of the graphene oxide dispersion liquid in Preparation Example 1 in 220 parts of pure water for 0.2 h. Then add 5 parts of a water reducing agent to the dispersed solution, and then pour this mixture into a mixture of 400 parts of cement and 1200 parts of river sand, and stir for 2 min to obtain the finished cement mortar.

[0055] Example 4 Graphene Oxide-Modified Cement Mortar

[0056] Ultrasonically disperse 60 parts of the graphene oxide dispersion liquid in Preparation Example 1 in 205 parts of pure water for 0.2 h. Then add 5 parts of a water reducing agent to the dispersed solution, and then pour this mixture into a mixture of 400 parts of cement and 1200 parts of river sand, and stir for 2 min to obtain the finished cement mortar.

[0057] Example 5 Graphene Oxide-Modified Cement Mortar

[0058] Disperse 75 parts of the graphene oxide dispersion of Preparation Example 1 in 190 parts of pure water by ultrasonic dispersion for 0.2 h. Then add 5 parts of water reducing agent to the well-dispersed solution, and then pour this mixture into a mixture of 400 parts of cement and 1200 parts of river sand. After stirring for 2 min, the finished cement mortar is obtained.

[0059] Cement mortar modified with graphene oxide in Example 6

[0060] Disperse 90 parts of the graphene oxide dispersion of Preparation Example 1 in 175 parts of pure water by ultrasonic dispersion for 0.2 h. Then add 5 parts of water reducing agent to the well-dispersed solution, and then pour this mixture into a mixture of 400 parts of cement and 1200 parts of river sand. After stirring for 2 min, the finished cement mortar is obtained.

[0061] Cement mortar modified with graphene oxide in Example 7

[0062] Prepare the cement mortar modified with graphene oxide according to the method of Example 4. The difference is that the graphene oxide dispersion of Preparation Example 2 with the same weight parts is used to replace the graphene oxide dispersion of Preparation Example 1, and the other conditions are the same as those in Example 4. Thus, the finished cement mortar is obtained.

[0063] Cement mortar modified with graphene oxide in Example 8

[0064] Prepare the cement mortar modified with graphene oxide according to the method of Example 4. The difference is that the graphene oxide dispersion of Preparation Example 3 with the same weight parts is used to replace the graphene oxide dispersion of Preparation Example 1, and the other conditions are the same as those in Example 4. Thus, the finished cement mortar is obtained.

[0065] Cement mortar modified with graphene oxide in Example 9

[0066] Prepare the cement mortar modified with graphene oxide according to the method of Example 4. The difference is that the graphene oxide dispersion of Preparation Example 4 with the same weight parts is used to replace the graphene oxide dispersion of Preparation Example 1, and the other conditions are the same as those in Example 4. Thus, the finished cement mortar is obtained.

[0067] Comparative Example 1 Reference cement mortar modified with graphene oxide

[0068] Prepare the reference cement mortar modified with graphene oxide according to the method of Example 4. The difference is that the graphene oxide dispersion of Comparative Preparation Example 1 with the same weight parts is used to replace the graphene oxide dispersion of Preparation Example 1, and the other conditions are the same as those in Example 4. Thus, the finished cement mortar is obtained.

[0069] Comparative Example 2 Reference cement mortar modified with graphene oxide

[0070] Prepare the reference graphene oxide modified cement mortar according to the method of Example 4, except that the graphene oxide dispersion of Comparative Preparation Example 2 with the same weight is used to replace the graphene oxide dispersion of Preparation Example 1, and the remaining conditions are the same as those in Example 4, thus obtaining the finished cement mortar.

[0071] Comparative Example 3 Reference graphene oxide modified cement mortar

[0072] Prepare the reference graphene oxide modified cement mortar according to the method of Example 4, except that the graphene oxide dispersion of Comparative Preparation Example 3 with the same weight is used to replace the graphene oxide dispersion of Preparation Example 1, and the remaining conditions are the same as those in Example 4, thus obtaining the finished cement mortar.

[0073] Test Example

[0074] The graphene oxide modified cement mortars prepared in the above examples and comparative examples were respectively tested for fluidity, compressive strength, and flexural strength according to the following methods, and the results are shown in Table 1.

[0075] (1) Fluidity test: Test the fluidity according to the method in Standard GB / T8077-2000 "Test Methods for Homogeneity of Concrete Admixtures". Pour the graphene oxide modified cement mortar prepared in the above examples and comparative examples into a truncated cone mold and fill it up. Lift the truncated cone mold and measure the maximum diameter of the free flow of the cement mortar on the glass plane.

[0076] (2) Compressive strength and flexural strength test: Test the compressive strength and flexural strength performance of the cement mortars prepared in the examples and comparative examples according to the method in GB / T50080-2002, and the results are shown in Table 1.

[0077] Table 1

[0078]

[0079] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. A method for preparing a graphene oxide dispersion, characterized in that, The preparation method includes: S1. Conduct a first modification reaction on graphene oxide and a sulfonic acid group source compound in a first solution to obtain sulfonic acid group-modified graphene oxide; S2. Conduct a second modification reaction on the sulfonic acid group-modified graphene oxide obtained in step S1 and tea polyphenols in a second solution to obtain a graphene oxide dispersion; In step S1, the sulfonic acid group source compound is used in the form of a sulfonic acid group source compound solution; In step S1, the dosage of the graphene oxide is 1 to 5 parts by weight, and the dosage of the sulfonic acid group source compound solution is 150 to 250 parts by weight.

2. The preparation method of the graphene oxide dispersion liquid according to claim 1, characterized in that, In step S2, the dosage of the tea polyphenols is 0.3 to 0.7 parts by weight, and the dosage of the second solution is 200 to 400 parts by weight.

3. The preparation method of the graphene oxide dispersion liquid according to claim 1 or 2, characterized in that, The first modification reaction is a reaction carried out by stirring graphene oxide, a sulfonic acid group source compound, and a first solution.

4. The method for preparing the graphene oxide dispersion according to claim 1 or 2, characterized in that, The stirring time is 20 to 28 h.

5. The method for preparing the graphene oxide dispersion according to claim 1 or 2, characterized in that, The second modification reaction is a reaction carried out by stirring the sulfonic acid group-modified graphene oxide obtained in step S1, tea polyphenols, and a second solution.

6. The preparation method of the graphene oxide dispersion liquid according to claim 1 or 2, characterized in that, The stirring speed is 4000 to 6000 rpm, and the stirring time is 1 to 3 h.

7. The method for preparing the graphene oxide dispersion according to claim 1 or 2, wherein The sulfonic acid group source compound is selected from at least one of sulfuric acid, sulfurous acid, sodium lignosulfonate, and sodium dodecylbenzenesulfonate.

8. A graphene oxide dispersion prepared by the preparation method of the graphene oxide dispersion according to any one of claims 1 to 7.

9. A graphene oxide-modified cement mortar, characterized in that, The cement mortar contains the graphene oxide dispersion according to claim 8, a water reducing agent, water, cement, sand and soil, and optionally additives and auxiliary materials.

10. The graphene oxide modified cement mortar according to claim 9, wherein, The content of the graphene oxide dispersion is 15 to 90 parts by weight, the content of the water reducing agent is 3 to 7 parts by weight, the content of the water is 150 to 250 parts by weight, the content of the cement is 300 to 500 parts by weight, the content of the sand and soil is 1000 to 1500 parts by weight, the content of the additives is 0.6 to 2.5 parts by weight, and the content of the auxiliary materials is 1.2 to 3.0 parts by weight.

11. Use of the graphene oxide dispersion according to claim 8 and / or the graphene oxide-modified cement mortar according to claim 9 or 10 in the field of building materials.

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