Metal ruthenium-loaded nitrogen-doped graphene oxide catalyst, preparation method and application thereof, and method for degrading organic pollutants in water by activating persulfate

Abstract

The invention relates to the field of catalytic materials, and discloses a metal ruthenium loaded nitrogen-doped graphene oxide catalyst, a preparation method and application thereof, and a method for degrading organic pollutants in water by activating persulfate, the catalyst is formed by loading metal ruthenium on nitrogen-doped graphene oxide, and the catalyst has a two-dimensional layered structure; on the basis of the total weight of the catalyst, the doping amount of nitrogen in the catalyst is 3-8 wt%, and the loading amount of metal ruthenium is 2-6 wt%. The metal ruthenium-loaded nitrogen-doped graphene oxide catalyst provided by the invention is applied to activation of persulfate, can effectively degrade organic pollutants in water, and has the characteristics of excellent catalytic performance, strong anti-interference capability and high repeated utilization rate.

Description

Technical Field

[0001] The invention relates to the field of catalytic materials, and in particular to a metal ruthenium-loaded nitrogen-doped graphene oxide catalyst, a preparation method and application thereof, and a method for activating persulfate to degrade organic pollutants in water. Background Art

[0002] The overuse of antibiotics has led to serious pollution of water resources and posed a major threat to human health and industrial development.

[0003] Effective water treatment technologies mainly include biodegradation, adsorption and advanced oxidation processes. Among them, the persulfate-based advanced oxidation technology has significant advantages over the traditional Fenton advanced oxidation technology, such as the SO 4 - It has a higher redox potential, a wider pH range, a longer half-life, etc. Therefore, persulfate is the most commonly used oxidant, which can effectively remove antibiotics, has higher oxidation performance, better selectivity and lower toxicity.

[0004] The activation methods of persulfate include homogeneous activation method and heterogeneous activation method. Compared with the homogeneous activation method, the heterogeneous activation method has the advantages of low energy consumption, simple operation, and no secondary pollution to the environment. In the current research, when the heterogeneous activation method is used to activate persulfate to degrade organic pollutants in water, the problems of low catalytic efficiency and easy deactivation of the catalyst are prone to occur.

[0005] Carbon nanomaterials, such as carbon nanotubes and graphene, have the characteristics of surface chemical inertness, good electrical conductivity, large specific surface area and pore volume, and have been proven to have good catalytic effects in various degradation processes. Therefore, the introduction of carbon nanomaterials into environmental catalysis as a heterogeneous catalyst for the removal of organic pollutants in water has very good prospects.

[0006] CN106565008A discloses a method for degrading antibiotics in wastewater, which catalyzes ozone degradation of antibiotics in wastewater by preparing a graphene catalyst doped with nitrogen or phosphorus atoms. Ammonium nitrate and phosphorus pentoxide are used as precursors of nitrogen or phosphorus to dope and modify graphene oxide. Ozone activation experiments show that the catalyst can effectively degrade sulfamethoxazole. However, the catalyst is difficult to synthesize and has high cost. In addition, the catalyst effect is unclear in complex water environments and needs further exploration.

[0007] CN113101958A discloses a Fe / Zn composite carbon-based catalyst and its preparation method and application in activating persulfate to degrade organic matter in water. The catalyst is a solid phase Fe / Zn@NC catalyst with magnetism and a structure of Fe and Zn metal structures wrapped in carbon nanotubes. When it is used to activate persulfate to degrade pollutants in water, the molar ratio of organic pollutants to persulfate is 1:10-100, and the mass ratio of organic pollutants to catalyst is 1:5-100. When the material is used to activate persulfate, it has a high degradation rate for sulfamethoxazole, a significant degradation effect, and good reuse performance. However, the regeneration process of the catalyst needs to be calcined at 350°C, which will lead to further energy consumption. Although the catalyst can still maintain a certain degradation efficiency after three repeated uses, the catalytic performance is significantly reduced. In practical applications, the complex composition of wastewater will further affect the regeneration effect and reuse performance of the catalyst.

[0008] Therefore, it is of great significance to develop a new type of carbon-based heterogeneous catalyst with excellent catalytic performance for the degradation of organic pollutants. Summary of the invention

[0009] The purpose of the present invention is to provide a supported graphene catalytic material which is used for activating persulfate, effectively degrading organic pollutants in water and has excellent catalytic performance, strong anti-interference ability and high reuse rate.

[0010] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a metal ruthenium-loaded nitrogen-doped graphene oxide catalyst, which is composed of nitrogen-doped graphene oxide loaded with metal ruthenium, and the catalyst has a two-dimensional layered structure; based on the total weight of the catalyst, the nitrogen doping amount in the catalyst is 3-8wt%, and the metal ruthenium loading amount is 2-6wt%.

[0011] A second aspect of the present invention provides a method for preparing a metal ruthenium-supported nitrogen-doped graphene oxide catalyst, the method comprising:

[0012] (1) Under ultrasonic conditions, a graphene oxide suspension, a nitrogen source, and a ruthenium source are first contacted to obtain an intermediate I;

[0013] (2) drying the intermediate I to obtain intermediate II;

[0014] (3) calcining the intermediate II under a protective atmosphere to obtain the metal ruthenium-supported nitrogen-doped graphene oxide catalyst;

[0015] In step (1), the nitrogen source is at least one of dicyandiamide, melamine and urea; the ruthenium source is ruthenium chloride and / or ruthenium nitrate;

[0016] The doping amount of nitrogen in the metal ruthenium-supported nitrogen-doped graphene oxide catalyst is 3-8wt%, and the loading amount of metal ruthenium is 2-6wt%.

[0017] The third aspect of the present invention provides a metal ruthenium-loaded nitrogen-doped graphene catalyst prepared by the method described in the second aspect.

[0018] The fourth aspect of the present invention provides the use of metal ruthenium-supported nitrogen-doped graphene catalyst in activating persulfate to degrade organic pollutants in water;

[0019] The metal ruthenium-loaded nitrogen-doped graphene catalyst is the metal ruthenium-loaded nitrogen-doped graphene catalyst described in the first aspect and / or the third aspect.

[0020] The fifth aspect of the present invention provides a method for activating persulfate to degrade organic pollutants in water, the method comprising: contacting and mixing wastewater containing organic pollutants, persulfate and a catalyst, wherein the catalyst is the metal ruthenium-loaded nitrogen-doped graphene catalyst described in the first aspect and / or the third aspect.

[0021] Through the above technical solution, the present invention has at least the following advantages:

[0022] (1) The metal ruthenium-loaded nitrogen-doped graphene catalyst provided by the present invention has excellent catalytic performance and anti-interference performance. At the same time, it has the advantages of stable chemical properties and a wide range of applications in practical applications.

[0023] (2) The metal ruthenium-loaded nitrogen-doped graphene catalyst provided by the present invention is easy to recycle and has a high reuse rate, showing excellent recycling performance.

[0024] (3) The preparation method of the metal ruthenium-loaded nitrogen-doped graphene catalyst provided by the present invention is simple, environmentally friendly and has low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of the structure of metal ruthenium-supported nitrogen-doped graphene oxide catalyst A1;

[0026] Figure 2 is a transmission electron microscope image of metal ruthenium-supported nitrogen-doped graphene oxide catalyst A1;

[0027] Figure 3 (a) is a scanning electron microscope image of graphene oxide. Figure 3 (b) is a scanning electron microscope image of metal ruthenium supported nitrogen-doped graphene oxide catalyst A1;

[0028] Figure 4 This is the scanning electron microscope energy spectrum EDS image of metal ruthenium supported nitrogen-doped graphene oxide catalyst A1;

[0029] Figure 5 It is the X-ray photoelectron spectrum of metal ruthenium supported nitrogen-doped graphene oxide catalyst A1 and catalyst DA2;

[0030] Figure 6 This is a test chart of the anti-interference performance of metal ruthenium-supported nitrogen-doped graphene oxide catalyst A1;

[0031] Figure 7 This is a test chart of the cyclic stability of the metal ruthenium-loaded nitrogen-doped graphene oxide catalyst A1. DETAILED DESCRIPTION

[0032] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0033] As mentioned above, the first aspect of the present invention provides a metal ruthenium-loaded nitrogen-doped graphene oxide catalyst, which is composed of nitrogen-doped graphene oxide loaded with metal ruthenium, and the catalyst has a two-dimensional layered structure; based on the total weight of the catalyst, the nitrogen doping amount in the catalyst is 3-8wt%, and the metal ruthenium loading amount is 2-6wt%.

[0034] Preferably, the weight ratio of nitrogen to metal ruthenium in the catalyst is 1:0.6-1.4. The inventors of the present invention have found that under this preferred condition, the metal ruthenium-supported nitrogen-doped graphene oxide catalyst prepared by the present invention has better catalytic performance and chemical stability.

[0035] In the present invention, the nitrogen doping amount and the metal ruthenium loading amount in the catalyst are measured by scanning electron microscope energy spectrum analysis.

[0036] As mentioned above, the second aspect of the present invention provides a method for preparing a metal ruthenium-supported nitrogen-doped graphene oxide catalyst, the method comprising:

[0037] (1) Under ultrasonic conditions, a graphene oxide suspension, a nitrogen source, and a ruthenium source are first contacted to obtain an intermediate I;

[0038] (2) drying the intermediate I to obtain intermediate II;

[0039] (3) calcining the intermediate II under a protective atmosphere to obtain the metal ruthenium-supported nitrogen-doped graphene oxide catalyst;

[0040] In step (1), the nitrogen source is at least one of dicyandiamide, melamine and urea; the ruthenium source is ruthenium chloride and / or ruthenium nitrate;

[0041] The doping amount of nitrogen in the metal ruthenium-supported nitrogen-doped graphene oxide catalyst is 3-8wt%, and the loading amount of metal ruthenium is 2-6wt%.

[0042] According to a preferred embodiment, in step (1), the molar ratio of the content of the ruthenium source to the nitrogen source calculated as nitrogen element is 1:80-120, and the mass ratio of the content of the ruthenium source to the graphene oxide suspension calculated as graphene oxide is 1:1.2-2. The inventors of the present invention have found that in this specific preferred case, the metal ruthenium-supported nitrogen-doped graphene catalyst provided by the present invention has higher catalytic activity and better anti-interference performance.

[0043] According to a more preferred embodiment, the conditions for the first contact include: a temperature of 15-30° C. and a time of 15-20 min.

[0044] According to a preferred embodiment, in step (2), the drying conditions include: a temperature of -20°C to -40°C and a time of 24-36 hours. The inventors of the present invention have found that in this specific preferred case, the metal ruthenium-supported nitrogen-doped graphene catalyst provided by the present invention has better dispersibility and more stable recycling performance.

[0045] According to a particularly preferred embodiment, in step (3), the calcination treatment conditions include: a temperature of 600-800° C. and a time of 2-3 h.

[0046] Preferably, in step (3), the protective atmosphere is a pure nitrogen atmosphere.

[0047] More preferably, the calcination treatment conditions also include: a heating rate of 5-10°C / min.

[0048] According to a specific embodiment, the preparation method of the metal ruthenium-supported nitrogen-doped graphene oxide catalyst comprises:

[0049] S1. Dissolving graphene oxide in deionized water at room temperature to form a graphene oxide suspension; contacting the graphene oxide suspension with a ruthenium source and a nitrogen source for a first time, and ultrasonically mixing for 15-20 minutes to obtain an intermediate I;

[0050] S2, drying the intermediate I obtained above to obtain intermediate II; the drying conditions include: temperature of -20°C to -40°C, time of 28-32h;

[0051] S3. Under a nitrogen atmosphere, the intermediate II is placed in a tube furnace, the temperature of the tube furnace is increased to 600-800°C at a rate of 5-10°C / min, the temperature is maintained for 2-3 hours, and the catalyst is naturally cooled to room temperature to obtain a metal ruthenium-loaded nitrogen-doped graphene oxide catalyst.

[0052] As mentioned above, the third aspect of the present invention provides a metal ruthenium-loaded nitrogen-doped graphene catalyst prepared by the method described in the second aspect.

[0053] As mentioned above, the fourth aspect of the present invention provides the use of metal ruthenium supported nitrogen-doped graphene catalyst in activating persulfate to degrade organic pollutants in water;

[0054] The metal ruthenium-loaded nitrogen-doped graphene catalyst is the metal ruthenium-loaded nitrogen-doped graphene catalyst described in the first aspect and / or the third aspect.

[0055] As mentioned above, the fifth aspect of the present invention provides a method for activating persulfate to degrade organic pollutants in water, the method comprising: contacting and mixing wastewater containing organic pollutants, persulfate and a catalyst, wherein the catalyst is the metal ruthenium-loaded nitrogen-doped graphene catalyst described in the first aspect and / or the third aspect.

[0056] According to a preferred embodiment, the contact mixing conditions include: temperature of 20-45° C. and time of 30-120 min.

[0057] According to a more preferred embodiment, the pH value of the wastewater is 5-9.

[0058] Preferably, the mass ratio of the catalyst to the organic pollutant is 1:0.5-5, and the molar ratio of the organic pollutant to the persulfate is 1:5-30.

[0059] Preferably, the persulfate is at least one of sodium persulfate, potassium persulfate, sodium permonosulfate, potassium permonosulfate and potassium hydrogen persulfate.

[0060] Preferably, the organic pollutant is at least one of sulfonamide compounds, phenolic compounds and tetracycline compounds.

[0061] Further preferably, the organic pollutant is a sulfonamide compound.

[0062] Particularly preferably, the organic pollutant is sulfamethoxazole. The inventors of the present invention have found that in this preferred case, the metal ruthenium-supported nitrogen-doped graphene catalyst prepared by the present invention has more stable chemical properties and higher reusability.

[0063] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all the instruments and raw materials used are commercially available.

[0064] Unless otherwise specified, room temperature in the present invention means 25±2°C.

[0065] Example 1

[0066] This embodiment is used to prepare a metal ruthenium-supported nitrogen-doped graphene catalyst, and the preparation method includes:

[0067] (1) dissolving graphene oxide in deionized water at room temperature to form a graphene oxide suspension; contacting the graphene oxide suspension with a ruthenium source and a nitrogen source for a first time, and ultrasonically mixing for 15 minutes to obtain an intermediate I;

[0068] (2) drying the intermediate I obtained above to obtain intermediate II; the drying conditions include: temperature of -30°C and time of 30 hours;

[0069] (3) Under a nitrogen atmosphere, the intermediate II was placed in a tube furnace, the temperature of the tube furnace was increased to 800° C. at a rate of 5° C. / min, the temperature was maintained for 2 h, and the catalyst was naturally cooled to room temperature to obtain catalyst A1.

[0070] The element composition of the catalyst A1 was tested by scanning electron microscope energy spectrum analysis, and the results showed that the doping amount of nitrogen was 3.5wt% and the loading amount of metal ruthenium was 4.2wt%.

[0071] Figure 1 is a schematic diagram of the structure of the metal ruthenium-supported nitrogen-doped graphene catalyst A1 prepared in Example 1, Figure 1 It can be seen that all atoms are distributed in the same graphene plane, and the molecular structure shows a periodic repeating unit. N atoms are doped in the graphene carbon skeleton; metal ruthenium (Ru) is loaded on the graphene skeleton as an active center, and partially forms coordination with N atoms.

[0072] Figure 2 is a transmission electron microscope image of the metal ruthenium-supported nitrogen-doped graphene catalyst A1 prepared in Example 1, Figure 2 It can be seen that the catalyst has a two-dimensional layered structure and there are bright spots on the surface of the catalyst, indicating that the metallic ruthenium is dispersed on the graphene skeleton and distributed relatively evenly.

[0073] Figure 3 (a) is the SEM characterization image of graphene oxide. Figure 3 (b) is a SEM characterization image of the metal ruthenium supported nitrogen-doped graphene catalyst A1 prepared in Example 1. Figure 3It can also be seen in (b) that the catalyst presents a layered structure, and the metal ruthenium has good dispersion on the graphene surface. Figure 3 (a) and Figure 3 In (b), it can be seen that the successful loading of metallic ruthenium does not change the structure of the original graphene oxide.

[0074] Figure 4 This is the scanning electron microscope energy spectrum EDS image of metal ruthenium supported nitrogen-doped graphene oxide catalyst A1, Figure 4 The elemental composition and content of catalyst A1 can be obtained. Specifically, the doping amount of nitrogen in catalyst A1 is 3.5wt%, and the loading amount of ruthenium is 4.2wt%.

[0075] Unless otherwise specified, Examples 2-3 are all carried out using a method similar to that of Example 1, except that some formulations or process parameters are different, as shown in Table 1.

[0076] Table 1

[0077]

[0078] Example 4

[0079] A similar method to Example 1 was used, except that the amount of ruthenium chloride was adjusted to 0.085 g, to obtain catalyst A4.

[0080] The element composition of the catalyst A4 was tested by scanning electron microscope energy spectrum analysis, and the results showed that the doping amount of nitrogen was 3.6wt% and the loading amount of metal ruthenium was 5.9wt%.

[0081] Comparative Example 1

[0082] A similar method to Example 1 was used, except that the amount of ruthenium chloride was adjusted to 0.1071 g, to obtain catalyst DA1.

[0083] The element composition of the catalyst DA1 was tested by scanning electron microscope energy spectrum analysis, and the results showed that the doping amount of nitrogen was 3.4 wt % and the loading amount of metal ruthenium was 6.4 wt %.

[0084] Comparative Example 2

[0085] The method is similar to that of Example 1, except that in step (1), no ruthenium source is added, and the remaining operations are the same as those of Example 1. Catalyst DA2 is obtained.

[0086] Figure 5 The X-ray photoelectron spectra of the ruthenium-supported nitrogen-doped graphene oxide catalyst A1 and catalyst DA2 are shown in Figure 1. Figure 5It can be seen from the results that, compared with catalyst DA2, catalyst A1 prepared in Example 1 has successfully loaded metal ruthenium.

[0087] Comparative Example 3

[0088] The method is similar to that of Example 1, except that in step (1), no ruthenium source and nitrogen source are added, and the remaining operations are the same as those of Example 1. Catalyst DA3 is obtained.

[0089] Test Case

[0090] This test example is used to test the catalytic performance, anti-interference performance, and recovery and recycling performance of the catalysts obtained in the above-mentioned Examples 1 to 4 and Comparative Examples 1 to 3.

[0091] (1) Catalytic performance test

[0092] a. Weigh 2 mg of the catalyst prepared in the above example and add it to a conical flask containing a pH of 9 and a concentration of 25.3 mg / L 100 mL sulfamethoxazole solution;

[0093] b. Place the conical flask in a constant temperature oscillator, adjust the speed to 170 rpm, the temperature to 25 ° C, and the time to 30 min;

[0094] c. Add 1 mmol / L potassium persulfate to the above conical flask, keep the rotation speed and temperature unchanged, and react for 120 minutes.

[0095] After the reaction is completed, the remaining amount of sulfamethoxazole in the solution is tested by ultraviolet spectrophotometer, and the degradation rate of sulfamethoxazole is calculated, thereby obtaining the catalytic performance of the catalyst in the catalytic oxidation of potassium persulfate to degrade sulfamethoxazole. The results are shown in Table 2.

[0096] In Table 2, the calculation formula for the degradation rate of sulfamethoxazole is:

[0097]

[0098] Among them, C 0 is the initial concentration of sulfamethoxazole solution, C t It is the remaining concentration of sulfamethoxazole after 120 minutes of reaction.

[0099] Table 2

[0100] Catalyst used Sulfamethoxazole degradation rate % A1 93.4 A2 94.1 A3 92.2 A4 93.2 DA1 89.3 DA2 74.2 DA3 70.3

[0101] It can be concluded from the results in Table 2 that when the metal ruthenium-loaded nitrogen-doped graphene oxide catalyst prepared by the present invention is used to catalyze the oxidation of potassium persulfate to degrade sulfamethoxazole, the degradation rate reaches more than 92.2%, indicating that the catalyst provided by the present invention has good catalytic performance.

[0102] (2) Anti-interference performance test

[0103] Prepare 6 250 mL conical flasks, add 2 mg of the catalyst A1 prepared in Example 1 and 100 mL of sulfamethoxazole solution with a pH of 9 and a concentration of 25.3 mg / L to each conical flask, add 1 mmol / L of potassium persulfate, and then add 10 mmol / L of interfering ion CO to 1-5 conical flasks respectively. 3 2- 、NO 3 - , Cl - , HCO 3 - 、SO 4 2- , no interfering ions are added to the sixth conical flask;

[0104] The subsequent operations are the same as step b and step c in the catalytic performance test of the above test example (1).

[0105] After the reaction was completed, the remaining amount of sulfamethoxazole in the above conical flasks was tested by ultraviolet spectrophotometer, and the degradation rate of sulfamethoxazole in each solution was calculated. The results are as follows: Figure 6 shown.

[0106] Depend on Figure 6 It can be seen that the interfering ion CO 3 2- 、NO 3 - , Cl - , HCO 3 - 、SO 4 2- In the presence of, using the metal ruthenium-loaded nitrogen-doped graphene oxide catalyst provided by the present invention, the degradation rate of sulfamethoxazole is maintained above 87.72%, indicating that the catalyst provided by the present invention has excellent anti-interference performance.

[0107] (3) Recycling and recycling performance

[0108] After the above-mentioned catalytic performance test run is completed, the catalyst A1 is filtered and separated from the reaction solution, the separated catalyst is washed with methanol, and dried under vacuum conditions at 60°C to obtain a recovered catalyst, and the recovered catalyst is reused under the same reaction conditions.

[0109] After five times of recycling and reuse, the degradation efficiency of catalyst A1 on sulfamethoxazole after recycling and reuse was measured. The results are as follows: Figure 7 shown.

[0110] Depend on Figure 7 It can be seen that the metal ruthenium-loaded nitrogen-doped graphene oxide catalyst prepared by the present invention still has a high degradation efficiency for sulfamethoxazole after five cycles of use, and the degradation efficiency remains above 80%, indicating that the catalyst provided by the present invention has long-term stability and excellent recycling performance.

[0111] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A metal ruthenium-supported nitrogen-doped graphene oxide catalyst, characterized in that: The catalyst is composed of nitrogen-doped graphene oxide loaded with metal ruthenium and has a two-dimensional layered structure. Based on the total weight of the catalyst, the doping amount of nitrogen in the catalyst is 3-8wt%, and the loading amount of metal ruthenium is 2-6wt%.

2. The catalyst according to claim 1, wherein The weight ratio of nitrogen to metal ruthenium in the catalyst is 1:0.6-1.

4.

3. A method for preparing a metal ruthenium-supported nitrogen-doped graphene oxide catalyst, characterized in that: The method includes: (1) Under ultrasonic conditions, a graphene oxide suspension, a nitrogen source, and a ruthenium source are first contacted to obtain an intermediate I; (2) drying the intermediate I to obtain intermediate II; (3) calcining the intermediate II under a protective atmosphere to obtain the metal ruthenium-supported nitrogen-doped graphene oxide catalyst; In step (1), the nitrogen source is at least one of dicyandiamide, melamine and urea; the ruthenium source is ruthenium chloride and / or ruthenium nitrate; The doping amount of nitrogen in the metal ruthenium-supported nitrogen-doped graphene oxide catalyst is 3-8wt%, and the loading amount of metal ruthenium is 2-6wt%.

4. The method according to claim 3, wherein: In step (1), the molar ratio of the content of the ruthenium source to the content of the nitrogen source calculated as nitrogen element is 1:80-120, and the mass ratio of the content of the ruthenium source to the content of the graphene oxide suspension calculated as graphene oxide is 1:1.2-2; And / or, the conditions of the first contact include: temperature of 15-30° C. and time of 15-20 min.

5. The method according to claim 3, wherein: In step (2), the drying conditions include: temperature of -20°C to -40°C and time of 24-36 hours.

6. The method according to claim 3, wherein: In step (3), the calcination treatment conditions include: temperature of 600-800°C and time of 2-3h.

7. A metal ruthenium-supported nitrogen-doped graphene catalyst prepared by the method according to any one of claims 2 to 6.

8. Application of ruthenium-loaded nitrogen-doped graphene catalyst in activating persulfate to degrade organic pollutants in water; The metal ruthenium-loaded nitrogen-doped graphene catalyst is the metal ruthenium-loaded nitrogen-doped graphene catalyst according to any one of claims 1-2 and 7.

9. A method for degrading organic pollutants in water by activating persulfate, characterized in that: The method comprises: contacting and mixing wastewater containing organic pollutants, persulfate and a catalyst, wherein the catalyst is a metal ruthenium-loaded nitrogen-doped graphene catalyst as described in any one of claims 1 to 2 and 7; And / or, the contact mixing conditions include: temperature of 20-45°C and time of 30-120 min; And / or, the pH value of the wastewater is 5-9.

10. The method according to claim 9, wherein: The mass ratio of the catalyst to the organic pollutant is 1:0.5-5, and the molar ratio of the organic pollutant to the persulfate is 1:5-30; And / or, the persulfate is at least one of sodium persulfate, potassium persulfate, sodium permonosulfate, potassium permonosulfate and potassium hydrogen persulfate; And / or, the organic pollutant is at least one of sulfonamide compounds, phenolic compounds and tetracycline compounds.

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