Process for the oxidation of graphite and use thereof

Abstract

This disclosure relates to a method for oxidizing graphite and its uses. The method includes: mixing graphite, concentrated acid, and potassium permanganate, heating and reacting to obtain a mixture; performing solid-liquid separation on the mixture to obtain graphite oxide and filtrate waste liquid; and refluxing the mixture of filtrate waste liquid and hydrogen peroxide in an open system to separate and extract the solid phase material to obtain manganese oxide. The mass ratio of hydrogen peroxide, potassium permanganate, and graphite is (50~500):(1~5):1, and the mass concentration of hydrogen peroxide is 0.01~2%. This method achieves the simultaneous production of manganese oxide during graphite oxidation without the need for an additional manganese source, simplifying the process. Furthermore, the reflux treatment in an open system provides mild reaction conditions and a simple process flow, effectively reducing the preparation cost of manganese oxide. Simultaneously, this method can significantly reduce the content of manganese ions and other pollutants in wastewater, solving the problem of environmental pollution caused by wastewater discharge during graphite oxidation.

Description

Technical Field

[0001] This disclosure pertains to the field of graphite oxidation, specifically relating to a method for oxidizing graphite and its applications. Background Technology

[0002] Graphite oxide is a compound composed of carbon, hydrogen, and oxygen elements, with a carbon-to-oxygen ratio between 2.1 and 2.9. Its formal name is graphite oxide or graphitic acid. It is a yellow solid that retains the layered structure of graphite. Common preparation methods include the modified Hummers process: Dry graphite is ground into powder, then interlayer dispersants such as sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, and benzoyl peroxide are added, followed by potassium ferrate, and then cured. The graphite is then added to a reactor, concentrated sulfuric acid is added and stirred until homogeneous, and the reaction is carried out in a water bath. Nitric acid is then added and the reaction is stirred again. The reactants are slowly poured into deionized water and stirred until the reaction is complete. Hydrogen peroxide is then introduced, and after washing, centrifugation, and drying, graphite oxide is obtained. However, this method involves complex reagents and relatively large quantities: it requires the use of various special interlayer dispersants, such as sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, and benzoyl peroxide. The addition of these reagents increases the complexity of the reaction system and the cost, and can easily lead to problems such as difficulty in wastewater treatment. Summary of the Invention

[0003] The purpose of this invention is to provide a method for oxidizing graphite and its applications. This invention utilizes an oxidation method to prepare graphite oxide while simultaneously producing manganese oxides, significantly reducing the content of manganese ions and other pollutants in the wastewater, thus solving the problem of environmental pollution caused by wastewater discharge.

[0004] To achieve the above objectives, a first aspect of the present invention provides a method for oxidizing graphite, wherein the method includes: S1. Graphite, concentrated acid and potassium permanganate are mixed and heated to react to obtain a mixture. S2. The mixture is subjected to solid-liquid separation to obtain graphite oxide and filtered waste liquid; S3. In an open system, the mixture containing the filtration waste liquid and hydrogen peroxide is refluxed to separate and remove the solid material to obtain manganese oxide. The mass ratio of hydrogen peroxide, potassium permanganate and graphite is (50~500):(1~5):1, and the mass concentration of hydrogen peroxide is 0.01~2%.

[0005] Optionally, the graphite is one or more of natural flake graphite, natural cryptocrystalline graphite, and artificial graphite; The graphite has a carbon content of 95% or more by weight, an ash content of less than 2%, and a mesh size of 20 to 500 mesh.

[0006] Optionally, the concentrated acid is selected from one or more of sulfuric acid, nitric acid, and perchloric acid.

[0007] Optionally, the mass ratio of the concentrated acid to the graphite is (25~75):1.

[0008] Optionally, the carbon-oxygen molar ratio of the graphite oxide is 2.0 to 3.0.

[0009] Optionally, the mass ratio of hydrogen peroxide to graphite is (80~400):1, and the mass concentration of hydrogen peroxide is 0.05~1%; the mass ratio of potassium permanganate to graphite is (3~5):1.

[0010] Optionally, in step S1, the mixing temperature is below 40°C, preferably below 30°C, more preferably below 20°C, and the mixing time is 0.1~8h, preferably 0.5~5h; the heating reaction temperature is 30~80°C, preferably 40~60°C, and the time is 0.1~8h, preferably 0.5~5h.

[0011] Optionally, in step S3, the reflux treatment conditions include: a temperature of 100~180℃, preferably 120~150℃, and a time of 2~96h, preferably 12~48h.

[0012] A second aspect of the present invention provides a manganese oxide prepared using the method provided in the first aspect of the present invention.

[0013] The third aspect of this invention provides the use of the manganese oxide described in the second aspect of this invention in the field of removing methanal; The material containing methanal is brought into contact with the manganese oxide material for reaction; the conditions for the contact reaction include: temperature of 20~80℃, pressure of 0.1~3MPa, and space velocity of 10~10000h⁻¹. -1 Preferably, the temperature is 30~60℃, the pressure is 0.2~2MPa, and the space velocity is 50~5000h. -1 The material contains less than 5% by mass of methanal, preferably less than 2%, and the material is one or more of hydrogen, nitrogen and inert gases, preferably hydrogen and / or nitrogen.

[0014] Through the above technical solution, this invention utilizes an oxidation method to prepare graphite oxide while simultaneously producing manganese oxides, eliminating the need for an additional manganese source, simplifying the process. Furthermore, this invention employs reflux treatment in an open system, maintaining atmospheric pressure throughout the reaction, resulting in mild reaction conditions and a simple process flow, effectively reducing the preparation cost of manganese oxides. Simultaneously, the preparation process significantly reduces the content of manganese ions and other pollutants in wastewater, effectively solving problems such as difficult wastewater discharge and environmental pollution. The manganese dioxide material prepared by this invention exhibits excellent performance in the removal of formic acid.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0016] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0017] The first aspect of this disclosure provides a method for oxidizing graphite, wherein the method includes: S1. Graphite, concentrated acid and potassium permanganate are mixed and heated to react to obtain a mixture. S2. The mixture is subjected to solid-liquid separation to obtain graphite oxide and filtered waste liquid; S3. In an open system, the mixture containing the filtration waste liquid and hydrogen peroxide is refluxed to separate and remove the solid material to obtain manganese oxide. The mass ratio of hydrogen peroxide, potassium permanganate, and graphite is (50~500):(1~5):1, and the mass concentration of hydrogen peroxide is 0.01~2%. The hydrogen peroxide refers to an aqueous solution of hydrogen peroxide, that is, the mass ratio of hydrogen peroxide, potassium permanganate, and graphite is the mass ratio of aqueous solution of hydrogen peroxide, potassium permanganate, and graphite.

[0018] This disclosure utilizes an oxidation method to prepare graphite oxide while simultaneously producing manganese oxides, eliminating the need for an additional manganese source, thus simplifying the process. Furthermore, this disclosure employs reflux treatment in an open system, maintaining atmospheric pressure throughout the reaction, resulting in mild reaction conditions and a simple process flow, effectively reducing the preparation cost of manganese oxides. Simultaneously, the preparation process significantly reduces the content of manganese ions and other pollutants in wastewater, effectively solving problems such as difficult wastewater discharge and environmental pollution.

[0019] In one specific embodiment, the graphite is one or more of natural flake graphite, natural cryptocrystalline graphite, and artificial graphite, preferably natural flake graphite; the carbon content of the graphite is 95% by weight or more, preferably 99% by weight or more, the ash content is less than 2%, preferably less than 1%, and the mesh size is 20 to 500 mesh, preferably 30 to 200 mesh.

[0020] In one specific embodiment, the concentrated acid is selected from one or more of sulfuric acid, nitric acid, and perchloric acid, preferably concentrated sulfuric acid; A0 is any concentration between M-10% and M+10%, preferably A0 is any concentration between M-5% and M+5%, A0 is the concentration of the concentrated acid, and M is the highest concentration of the concentrated acid at analytical grade reagent level.

[0021] In the above embodiments, by selecting preferred types of graphite and concentrated acid, as well as the carbon content and acid concentration, it is beneficial to improve the performance of the prepared graphite oxide.

[0022] In one specific embodiment, the mass ratio of the concentrated acid to the graphite is (10~100):1, preferably (25~75):1.

[0023] In one specific embodiment, the carbon-oxygen molar ratio of the graphite oxide is 1.5 to 3.5, preferably 2.0 to 3.0.

[0024] The oxygen content of the graphite oxide prepared in this disclosure is moderate, and it has significant advantages in fire prevention and flame retardancy after thermal expansion and exfoliation.

[0025] In a preferred embodiment, the mass ratio of hydrogen peroxide to graphite is (80~400):1; the mass ratio of potassium permanganate to graphite is (3~5):1. In a further specific embodiment, the mass ratio of potassium permanganate to graphite can be 3:1, 4:1, 5:1, or any value between the two. In the above embodiments, controlling the amount of hydrogen peroxide, potassium permanganate, and graphite added within the preferred range of this application can further improve the performance of manganese oxides in the reaction process of removing formic acid, and further improve the formic acid removal rate.

[0026] In a preferred embodiment, the mass concentration of the hydrogen peroxide is 0.05-1%. In a further specific embodiment, the mass concentration of the hydrogen peroxide can be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 1%, or any value between the two.

[0027] In one specific embodiment, in step S1, the mixing temperature is below 40°C, preferably below 30°C, more preferably below 20°C, and the mixing time is 0.1~8h, preferably 0.5~5h; the heating reaction temperature is 30~80°C, preferably 40~60°C, and the time is 0.1~8h, preferably 0.5~5h.

[0028] In one specific embodiment, in step S3, the reflux treatment temperature is 100~180℃, preferably 120~150℃, and the time is 2~96h, preferably 12~48h.

[0029] In this disclosure, separating and removing solid materials refers to filtering out the solid phase and then washing and drying it. Filtration, washing, and drying are all conventional operations in the art and have no special requirements.

[0030] The second aspect of this disclosure provides a manganese oxide prepared using the method provided in the first aspect of this disclosure.

[0031] This disclosure produces manganese oxide while oxidizing graphite, and the method provided by this disclosure can significantly reduce the content of manganese ions and other substances in wastewater, thus solving the problem of environmental pollution caused by wastewater discharge during the preparation of graphite oxide.

[0032] This third aspect of the disclosure provides the use of the manganese oxides described in the second aspect of the disclosure in the field of removing methanal.

[0033] In one specific embodiment, a material containing methanal is brought into contact with and reacted with a manganese oxide material provided in the second aspect of this disclosure.

[0034] In one specific embodiment, the conditions for the contact reaction include: a temperature of 20~80℃, a pressure of 0.1~3MPa, and a space velocity of 10~10000h⁻¹. -1 Preferably, the temperature is 30~60℃, the pressure is 0.2~2MPa, and the space velocity is 50~5000h. -1 The material contains less than 5% by mass of methanal, preferably less than 2% by mass, and the material is one or more of hydrogen, nitrogen and inert gases, preferably hydrogen and / or nitrogen.

[0035] The present invention will be further illustrated by the following examples, but the invention is not limited thereto. All reagents used in this disclosure are commercially available analytical grade reagents. The flake graphite has a carbon content of 99.3% by weight or more, an ash content of 0.4%, and a mesh size of 50.

[0036] Example 1 S1. Add concentrated sulfuric acid (mass concentration greater than 98%), potassium permanganate and 2g of graphite to a beaker, stir and mix at 15℃ for 1h, and then stir and react at 45℃ under autogenous pressure for 2h to obtain a mixture; wherein the mass ratio of potassium permanganate to graphite is 3:1; and the mass ratio of concentrated acid to graphite is 35:1.

[0037] S2. The mixture is subjected to solid-liquid separation to obtain graphite oxide and filtrate waste liquid; the carbon-oxygen molar ratio of graphite oxide is 2.3; S3. In an open system, 170 ml of hydrogen peroxide (mass concentration of 0.05%) was added to the filtered waste liquid to obtain a mixture. The mixture was then refluxed at 140°C for 24 hours in an open system. The solid phase material was then separated to obtain manganese oxide. The mass ratio of hydrogen peroxide to graphite was 85:1.

[0038] Example 2 The preparation method in Example 1 is used, except that in step S1, the mass ratio of potassium permanganate to graphite is 1:1.

[0039] Example 3 The preparation method in Example 1 is used, except that in step S3, the reflux temperature is 100°C and the reflux treatment time is 2 hours.

[0040] Example 4 The preparation method in Example 1 is used, except that in step S3, 500 ml of hydrogen peroxide of the same concentration is added.

[0041] Example 5 The preparation method in Example 1 is used, except that in step S3, 170 ml of hydrogen peroxide with a mass concentration of 1.5% is added.

[0042] Comparative Example 1 The preparation method in Example 1 is used, except that in step S1, the mass ratio of potassium permanganate to graphite is 6:1.

[0043] Comparative Example 2 The preparation method in Example 1 is used, except that in step S3, 15 ml of hydrogen peroxide of the same concentration is added, and the mass ratio of hydrogen peroxide to graphite is 7.5:1.

[0044] Comparative Example 3 The preparation method in Example 1 was used, except that in step S3, 170 ml of hydrogen peroxide with a mass concentration of 8% was added.

[0045] Comparative Example 4 The preparation method used is the same as that in Example 1, except that reflux treatment was not performed in step S3.

[0046] Test case At room temperature and 0.3 MPa, 5.0 g of the manganese oxide prepared in Examples 1-5 and Comparative Examples 1-4 of this disclosure was packed into the middle of a fixed-bed reaction tube with a diameter of 10 mm, and both ends were filled with quartz wool. The reaction was carried out at a space velocity of 100 h⁻¹. -1 Formic aldehyde with a concentration of 1000 ppm (nitrogen was used as the balance gas) was introduced, and the removal rate of formic aldehyde was measured after 2 hours of reaction. The results are shown in Table 1.

[0047] Table 1

[0048] As can be seen from the test results in Table 1, the manganese oxide material prepared by the method provided by this invention, compared with the comparative example, can not only effectively remove methanal from the material, but also significantly reduce the manganese content in the filtration wastewater during the preparation process, thus solving the problem of wastewater discharge polluting the environment during the graphite oxidation process.

[0049] The test results of Comparative Examples 1-4 show that in Comparative Example 1, the amount of potassium permanganate was too high, resulting in a high manganese content in the graphite oxide filtration waste liquid. This led to excessively high manganese content in the prepared manganese oxide, partially damaging its structure, resulting in a large specific surface area and pore volume, and poor product performance. After 2 hours of reaction, the removal rate of methanal was significantly lower than that of Example 1, and the utilization rate of manganese in the waste liquid was also reduced. In Comparative Example 2, the amount of hydrogen peroxide was outside the limits of this invention, resulting in an insufficient oxidation reaction and a decline in the quality of the prepared manganese oxide product. After 2 hours of reaction, the removal rate of methanal was lower than that of Examples 1-5. In Comparative Example 3, the concentration of hydrogen peroxide was too high, resulting in a small specific surface area and pore volume in the prepared manganese oxide, and a significant decrease in the removal rate of methanal after 2 hours of reaction. In Comparative Example 4, no reflux treatment was performed, resulting in poor product performance and a lower methanal removal rate than that of the embodiments of this application.

[0050] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0051] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0052] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method of oxidizing graphite, wherein, The method includes: S1. Graphite, concentrated acid and potassium permanganate are mixed and heated to react to obtain a mixture. S2. The mixture is subjected to solid-liquid separation to obtain graphite oxide and filtered waste liquid; S3. In an open system, the mixture containing the filtration waste liquid and hydrogen peroxide is refluxed to separate and remove the solid material, thereby obtaining manganese oxide; The mass ratio of hydrogen peroxide, potassium permanganate and graphite is (50~500):(1~5):1, and the mass concentration of hydrogen peroxide is 0.01~2%.

2. The method of claim 1, wherein, The graphite is one or more of natural flake graphite, natural cryptocrystalline graphite, and artificial graphite. The graphite has a carbon content of 95% or more by weight, an ash content of less than 2%, and a mesh size of 20 to 500 mesh.

3. The method of claim 1, wherein, The concentrated acid is selected from one or more of sulfuric acid, nitric acid, and perchloric acid.

4. The method of claim 1, wherein, The mass ratio of the concentrated acid to the graphite is (25~75):

1.

5. The method of claim 1, wherein, The carbon-oxygen molar ratio of the graphite oxide is 2.0 to 3.

0.

6. The method of claim 1, wherein, The mass ratio of hydrogen peroxide to graphite is (80~400):1, and the mass concentration of hydrogen peroxide is 0.05~1%; the mass ratio of potassium permanganate to graphite is (3~5):

1.

7. The method of claim 1, wherein, In step S1, the mixing temperature is below 40°C, preferably below 30°C, more preferably below 20°C, and the mixing time is 0.1~8h, preferably 0.5~5h; the heating reaction temperature is 30~80°C, preferably 40~60°C, and the time is 0.1~8h, preferably 0.5~5h.

8. The method of claim 1, wherein, In step S3, the temperature of the reflux treatment is 100~180℃, preferably 120~150℃, and the time is 2~96h, preferably 12~48h.

9. Manganese oxide prepared by the method according to any one of claims 1 to 8.

10. The use of the manganese oxide according to claim 9 in the field of removing methanal; contacting a material containing formic acid with the manganese oxide material; the conditions of the contacting reaction include: temperature is 20-80℃, pressure is 0.1-3MPa, and space velocity is 10-10000h -1 ; preferably, temperature is 30-60℃, pressure is 0.2-2MPa, and space velocity is 50-5000h -1 ; the mass content of formic acid in the material is 5% or less, preferably 2% or less, and the material is one or more of hydrogen, nitrogen and inert gas, preferably hydrogen and / or nitrogen.

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