Method for regulating and controlling carboxyl functional groups on surface of carbon material based on ionization irradiation

Abstract

The invention belongs to the technical field of environmental engineering, and particularly discloses a method for regulating and controlling carboxyl functional groups on the surface of a carbon material based on ionization irradiation. The method comprises the following steps: firstly, adding a carbon material into a sodium hydroxide solution for reflux treatment, washing the treated carbon material with deionized water, adding the washed carbon material into a centrifugal tube containing deionized water, and then introducing carbon dioxide or nitrous oxide gas. And carrying out irradiation treatment on the centrifugal tube containing the carbon material, and carrying out vacuum filtration and drying on the treated carbon material solution to obtain the carbon material rich in carboxyl functional groups. The method disclosed by the invention has the advantages of simplicity in operation, controllable carboxyl functional group content, easiness in amplified application and the like, can be used for carrying out modification treatment on a carbon material, and has an application prospect in the aspect of carbon-based material modification.

Description

Technical Field

[0001] The invention relates to a method for regulating carboxyl functional groups of carbon materials based on ionizing radiation, and belongs to the technical field of environmental engineering. Background Art

[0002] Heterogeneous Fenton-like oxidation technology can effectively treat refractory organic pollutants in water. The oxidation capacity of this technology mainly depends on heterogeneous catalysts. Carbon materials are widely used as Fenton-like catalysts due to their large specific surface area and stable performance. Studies have shown that the functional groups of carbon materials, such as oxygen-containing functional groups and nitrogen-containing functional groups, can regulate the electron distribution of carbon materials, thereby affecting the catalytic activity of carbon materials. In order to improve the catalytic activity of carbon materials, many scholars have carried out research on regulating the surface electron distribution of carbon materials. Among them, adding carboxyl functional groups has been proven to be an effective method to enhance the Fenton-like catalytic activity of carbon materials. Especially in the field of monopersulfate-based catalysis, carboxyl functional groups can induce monopersulfate activation to produce highly selective singlet oxygen, providing a solution for the selective removal of refractory organic pollutants in water. However, how to regulate the carboxyl functional groups on the surface of carbon materials has always been a difficult point.

[0003] Pyrolysis is currently a commonly used method for regulating carboxyl functional groups, but it is difficult to accurately regulate the content of carboxyl functional groups. Patent (CN 113289655 B) discloses a method for regulating the surface functional groups of carbon materials by pyrolysis. In its invention, phenol solution 1 is first obtained by mixing sodium phenolate solution with acyl chloride. Then the phenol solution is oxidized to obtain phenol solution 2, and phenol solution 1 and phenol solution 2 are mixed and dried to obtain phenol solution 4. Then, phenol solution 4 is pyrolyzed to obtain a carbon material with rich oxygen-containing and nitrogen-containing functional groups on the surface. This patent can increase the surface functional groups of carbon materials, but it cannot achieve accurate regulation of the type and concentration of oxygen-containing functional groups, and organic waste liquid will be generated during the regulation process. Patent (CN 109796003 B) discloses a method for regulating the oxygen functional groups on the surface of coal-based hard carbon. In its invention, the raw materials are first crushed, ground and sieved, then carbonized at high temperature, and finally ball milled under different atmospheres. The material after ball milling is cleaned and dried to obtain a coal-based hard carbon material containing oxygen functional groups. This patent can regulate the oxygen-containing functional groups on the surface of coal-based hard carbon materials, but the high temperature required in the regulation process is 1000-1700°C, and specific atmosphere conditions are required, such as high-purity nitrogen or high-purity argon. The overall preparation process is relatively complicated and the cost is high. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the high temperature and complex operation problems required by the existing technology for regulating oxygen-containing functional groups on the surface of carbon materials, and to provide a method for regulating the carboxyl functional groups of carbon materials based on ionizing radiation, which can economically and effectively achieve the regulation of oxygen-containing functional groups on the surface of carbon materials.

[0005] The present invention uses ionizing radiation to directly treat the carbon material aqueous solution, so as to realize the directional loading of oxygen-containing functional groups on the surface of the carbon material. Moreover, the content of oxygen-containing functional groups can be regulated by controlling the irradiation conditions. The entire operation process is simple, low in cost, and the content of oxygen-containing functional groups can be quantitatively regulated, providing an economical and effective method for regulating oxygen-containing functional groups on the surface of carbon materials.

[0006] To solve the above problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for regulating carboxyl functional groups on the surface of carbon materials based on ionizing radiation. The specific technical scheme is as follows:

[0008] 1) adding the carbon material to a sodium hydroxide solution for reflux treatment, and then washing with deionized water;

[0009] 2) adding the washed carbon material in step 1) into a container containing deionized water, introducing gas into the solution, and then sealing the container;

[0010] 3) treating the sealed container in step 2) by irradiation;

[0011] 4) The irradiated solution in step 3) is vacuum filtered, and the obtained solid is vacuum dried to obtain a carbon material containing carboxyl functional groups.

[0012] In some preferred embodiments, the carbon material is selected from any one or a combination of at least two of the following groups: graphene, graphene oxide, activated carbon, biochar, carbon nanotubes and graphitic carbon nitride.

[0013] In some preferred embodiments, the concentration of the sodium hydroxide solution is 0.5-2 mol / L.

[0014] In some preferred embodiments, the reflux treatment time is 36 to 48 hours; for example, it can be 37 hours, 38 hours, 40 hours, 42 hours, 44 hours, 46 hours or 47 hours.

[0015] In some preferred embodiments, the volume ratio of the carbon material to deionized water is 0.5-1.

[0016] In some preferred embodiments, the types of the introduced gas include: carbon dioxide and / or nitrous oxide.

[0017] In some preferred embodiments, the irradiation dose of the irradiation treatment is 2-100 kGy, for example, 10-90 kGy, 20-80 kGy, 30-70 kGy, 40-60 kGy, 25 kGy, 35 kGy, 45 kGy, 50 kGy, 55 kGy, 65 kGy, 75 kGy, 85 kGy or 95 kGy.

[0018] In some preferred embodiments, the radiation source of the radiation treatment is an electron accelerator, 60 Co or 137 Cs.

[0019] In some preferred embodiments, the vacuum drying temperature is 45-70°C, preferably 45°C; for example, it can be 48°C, 50°C, 52°C, 55°C, 57°C, 60°C or 65°C.

[0020] In some preferred embodiments, the vacuum drying time is 8 to 20 hours, preferably 12 hours; for example, it can be 10 hours, 12 hours, 15 hours, 17 hours, 18 hours or 19 hours.

[0021] More preferably, the vacuum drying condition is placing in an oven at 45° C. for 12 hours.

[0022] On the other hand, the present invention also provides a carbon material containing carboxyl functional groups prepared by the method.

[0023] In some preferred embodiments, in the carbon material containing carboxyl functional groups, the proportion of surface carboxyl functional groups is 10-80%.

[0024] The beneficial effects of the present invention are at least:

[0025] (1) Compared with the traditional process of regulating oxygen-containing functional groups on the surface of carbon materials, the present invention has the advantages of simple operation, low cost and no generation of organic waste liquid.

[0026] (2) Compared with the commonly used pyrolysis method, ionizing radiation preparation has the advantages of simple operation and scalable production, and the content of oxygen-containing functional groups can be regulated by controlling the irradiation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the reaction process;

[0028] Figure 2 This is the infrared characterization comparison spectrum of the material before and after irradiation. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. In the specific examples of the present invention, the raw materials used can be obtained commercially. Unless otherwise specified, the temperature in the context is given in degrees Celsius. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0030] The present invention provides a method for regulating carboxyl functional groups of carbon materials based on ionizing radiation. The present invention is further described below in conjunction with embodiments and drawings.

[0031] Example 1

[0032] like Figure 1 As shown, 1) 0.2 g of graphene was added to 1M sodium hydroxide solution and refluxed for 48 h, the refluxed graphene was added to 100 ml of deionized water, stirred for 30 min, and then vacuum filtered. This process was repeated 3 times.

[0033] 2) The washed carbon material was added into a centrifuge tube containing 5 ml of deionized water, nitrous oxide was introduced into the solution, and then the centrifuge tube was sealed.

[0034] 3) The centrifuge tube was irradiated with a dose of 10 kGy.

[0035] 4) The mixed solution in the centrifuge tube after the irradiation treatment in step 3) is vacuum filtered, and then the obtained solid is vacuum dried to finally obtain a carbon material rich in carboxyl functional groups.

[0036] The proportion of surface carboxyl functional groups calculated according to the method in the national standard GB / T38114-2019 is 27.2%.

[0037] Comparative Example 1

[0038] Based on Example 1, the carbon material is prepared without ionizing radiation.

[0039] Conclusion: The carbon materials prepared in Example 1 and Comparative Example 1 were subjected to infrared detection. Figure 2 As shown, by comparison, it can be clearly seen that the carboxyl functional group increases significantly after irradiation, and the carbon material without ionizing irradiation does not show characteristic peaks of carboxyl functional groups or other carbon-oxygen bonds in its infrared characterization spectrum. It proves that the carbon material prepared by the method described in this application can significantly increase the content of carboxyl functional groups on the surface of the material.

[0040] Example 2

[0041] 1) First, 0.2 g of graphene was added to 1 M sodium hydroxide solution and refluxed for 48 h. The refluxed graphene was added to 100 ml of deionized water, stirred for 30 min, and then vacuum filtered. This process was repeated 3 times.

[0042] 2) The washed carbon material was added into a centrifuge tube containing 5 ml of deionized water, nitrous oxide was introduced into the solution, and then the centrifuge tube was sealed.

[0043] 3) The centrifuge tube was irradiated with a dose of 50 kGy.

[0044] 4) The mixed solution in the centrifuge tube after the irradiation treatment in step 3) is vacuum filtered, and then the obtained solid is vacuum dried to finally obtain a carbon material rich in carboxyl functional groups, with a surface carboxyl functional group ratio of 44.6%.

[0045] Example 3

[0046] 1) First, 0.2 g of graphene was added to 1 M sodium hydroxide solution and refluxed for 48 h. The refluxed graphene was added to 100 ml of deionized water, stirred for 30 min, and then vacuum filtered. This process was repeated 3 times.

[0047] 2) The washed carbon material was added into a centrifuge tube containing 5 ml of deionized water, nitrous oxide was introduced into the solution, and then the centrifuge tube was sealed.

[0048] 3) The centrifuge tube was irradiated with a dose of 100 kGy.

[0049] 4) The mixed solution in the centrifuge tube after the irradiation treatment in step 3) is vacuum filtered, and then the obtained solid is vacuum dried to finally obtain a carbon material rich in carboxyl functional groups, with a surface carboxyl functional group ratio of 67.4%.

[0050] Conclusion: It can be seen from the above Examples 1 to 3 that by changing the dose of ionizing radiation, the proportion of carboxyl functional groups on the surface of the carbon material can be changed, thereby achieving regulation of the proportion of its functional groups, so that the proportion of carboxyl functional groups on the surface of the carbon material is distributed between 10 and 80%.

[0051] Example 4

[0052] 1) First, 0.2 g of graphene was added to a 2M sodium hydroxide solution and refluxed for 36 h. The refluxed graphene was added to 100 ml of deionized water, stirred for 30 min, and then vacuum filtered. This process was repeated 3 times.

[0053] 2) The washed carbon material was added into a centrifuge tube containing 5 ml of deionized water, nitrous oxide was introduced into the solution, and then the centrifuge tube was sealed.

[0054] 3) The centrifuge tube was irradiated with a dose of 20 kGy.

[0055] 4) The mixed solution in the centrifuge tube after the irradiation treatment in step 3) is vacuum filtered, and then the obtained solid is vacuum dried to finally obtain a carbon material rich in carboxyl functional groups, and the proportion of surface carboxyl functional groups is 53.4%.

[0056] Example 5

[0057] 1) First, 0.2 g of graphene was added to 1 M sodium hydroxide solution and refluxed for 48 h. The refluxed graphene was added to 100 ml of deionized water, stirred for 30 min, and then vacuum filtered. This process was repeated 3 times.

[0058] 2) The washed carbon material was added into a centrifuge tube containing 5 ml of deionized water, carbon dioxide was introduced into the solution, and then the centrifuge tube was sealed.

[0059] 3) The centrifuge tube was irradiated with a dose of 10 kGy.

[0060] 4) The mixed solution in the centrifuge tube after the irradiation treatment in step 3) is vacuum filtered, and then the obtained solid is vacuum dried to finally obtain a carbon material rich in carboxyl functional groups, with a surface carboxyl functional group ratio of 35.3%.

[0061] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation, characterized in that: Here are the steps: 1) adding the carbon material to a sodium hydroxide solution for reflux treatment, and then washing with deionized water; 2) adding the washed carbon material in step 1) into a container containing deionized water, introducing gas into the solution, and then sealing the container; 3) treating the sealed container in step 2) by irradiation; 4) The irradiated solution in step 3) is vacuum filtered, and the obtained solid is vacuum dried to obtain a carbon material containing carboxyl functional groups.

2. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The carbon material is selected from any one or a combination of at least two of the following groups: graphene, graphene oxide, activated carbon, biochar, carbon nanotubes and graphitic carbon nitride.

3. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The concentration of the sodium hydroxide solution is 0.5-2 mol / L.

4. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The reflux treatment time is 36 to 48 hours.

5. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The volume ratio of the carbon material to deionized water is 0.5-1.

6. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The types of the introduced gas include: carbon dioxide and / or nitrous oxide.

7. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The irradiation dosage of the irradiation treatment is 2 to 100 kGy.

8. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The radiation source of the radiation treatment is an electron accelerator, 60 Co or 137 Cs.

9. A method for regulating carboxyl functional groups of carbon materials based on ionizing radiation according to claim 1, wherein: The vacuum drying temperature is 45-70°C, preferably 45°C; and / or The vacuum drying time is 8 to 20 hours, preferably 12 hours. More preferably, the vacuum drying condition is placing in an oven at 45° C. for 12 hours.

10. A carbon material containing a carboxyl functional group prepared by the method according to any one of claims 1 to 9; In the carbon material containing carboxyl functional groups, the proportion of surface carboxyl functional groups is 10-80%.

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