Preparation method and application of monatomic catalyst for activating peroxymonosulfate

Abstract

The invention discloses a preparation method and application of a monatomic catalyst for activating peroxymonosulfate. The monatomic catalyst provided by the invention comprises a carrier and cobalt monatomic loaded on the carrier, the carrier is an oxygen-doped graphite phase carbon nitride nanosheet; the cobalt single atoms exist on the carrier in a well dispersed single atom structure. The monatomic catalyst disclosed by the invention has excellent capability of degrading organic pollutants, takes singlet oxygen as a key active oxygen species, and shows high selectivity, wide pH tolerance and adaptability to various complex water matrixes. Meanwhile, the monatomic catalyst disclosed by the invention has the potential of sustainable water purification application, so that the operation cost of a peroxymonosulfate activation technology is reduced, and the problem of ecological pollution caused by the use of a large amount of peroxymonosulfate is avoided.

Description

Technical Field

[0001] The present invention relates to the field of organic wastewater treatment, and particularly to a preparation method and application of a single-atom catalyst for activating peroxymonosulfate. Background Art

[0002] Advanced oxidation processes (AOPs) are a class of water treatment technologies that degrade organic pollutants in wastewater by generating highly reactive oxidizing species. These oxidizing species have extremely strong oxidation capabilities and can decompose complex organic pollutants into small-molecule organic substances or even completely mineralize them into carbon dioxide and water, thereby effectively removing toxic and harmful substances in wastewater. Due to their high efficiency, rapidity, wide applicability, etc., AOPs have become an important technology in the field of wastewater treatment, especially showing significant advantages in treating refractory persistent organic pollutants.

[0003] In recent years, among many AOPs technologies, the peroxymonosulfate (PMS)-based Fenton-like reaction has received extensive attention. PMS is a strong oxidant, and its molecular structure contains a peroxo bond. Under the action of a catalyst, it can be activated to generate highly reactive sulfate radicals and hydroxyl radicals. Compared with the traditional Fenton reaction, the PMS-based Fenton-like reaction has a wider pH application range and higher oxidation efficiency. However, the radicals are easily quenched by natural organic matter and inorganic ions present in the water body, resulting in a significant reduction in their oxidation ability. In addition, the non-selective oxidation characteristics of the radicals make it difficult to achieve the targeted degradation of pollutants in complex water bodies, and even more toxic halogenated by-products may be generated. Therefore, the development of new catalysts or technologies that can selectively target organic pollutants in complex wastewater environments has become the research focus in the current field of water treatment.

[0004] In this context, the emergence of single-atom catalysts (SACs) has brought a revolutionary breakthrough to the development of PMS activation technology. By anchoring metal atoms in a monodispersed form on the support, SACs maximize the utilization of metal atoms and provide highly uniform active sites. Compared with traditional catalysts, SACs have higher catalytic activity, selectivity, and stability. The strong interaction between the metal atoms and the support in single-atom catalysts not only causes changes in the electronic structure of the metal atoms, thereby endowing them with unique catalytic activity, but also effectively prevents the migration and aggregation of metal atoms, thus improving the stability of the catalyst. By regulation and selection of different support materials (such as graphene, carbon nitride, metal oxides, etc.) and metal atoms (such as iron, cobalt, nickel, platinum, etc.), the electronic structure and catalytic performance of single-atom catalysts can meet different reaction requirements. In addition, due to the high efficiency of single-atom catalysts, less noble metals (such as platinum, palladium, gold, etc.) can be used to achieve comparable or even higher catalytic performance than traditional catalysts, thus significantly reducing the material cost. However, although single-atom catalysts show excellent selectivity in the catalytic system, in complex reaction systems, how to precisely regulate their selectivity remains a challenge. For example, in wastewater treatment, how to avoid the generation of side reactions and toxic by-products still needs to be further solved. Moreover, under long-term operation or high-load reaction conditions, single-atom catalysts are prone to deactivation due to metal atom loss, support structure damage, or active site poisoning, which also hinders the practical application of single-atom catalysts in wastewater treatment. Research has shown that introducing multiple heteroatoms (such as nitrogen-oxygen co-doping, nitrogen-sulfur co-doping, etc.) into the support can precisely regulate the electronic structure and coordination environment of metal atoms, significantly enhance the stability of metal atoms, and enable them to remain in a monodispersed state even under high-temperature or strong acid / strong base conditions, with multiple advantages such as enhancing the metal atom anchoring ability, providing diverse active sites, improving conductivity, and chemical stability. These advantages make it have great application potential in the fields of energy conversion, environmental governance, chemical synthesis, etc.

[0005] Based on this, we attempt to anchor single cobalt atoms on graphitic carbon nitride nanosheets to improve the selectivity and efficiency of catalytic reactions, reduce the generation of by-products, and lower the risk of secondary pollution during wastewater treatment, showing significant advantages and durability in treating industrial wastewater, medical wastewater, and environmental water bodies containing refractory organic compounds, injecting new vitality into the development of single-atom catalysts. Summary of the Invention

[0006] In view of the above technical problems to be solved, the present invention provides a preparation method and application of a novel single-atom catalyst for activating peroxymonosulfate. The single-atom catalyst has excellent catalytic performance and stability, reduces the cost of the traditional PMS photoactivation system, improves the benefit, and enhances the pollutant removal efficiency of the persulfate activation system on the premise of avoiding subsequent addition of peroxymonosulfate.

[0007] To achieve the above object, the present invention provides a preparation method and application of a novel single-atom catalyst for activating peroxymonosulfate, and the method includes the following steps:

[0008] 1. A preparation method and application of a single-atom catalyst for activating peroxymonosulfate, characterized in that it includes a carrier and cobalt single atoms supported on the carrier; the carrier is oxygen-doped graphitic carbon nitride nanosheets; the cobalt single atoms exist on the carrier in a well-dispersed single-atom structure.

[0009] 2. The single-atom catalyst according to claim 1, characterized in that the mass of the cobalt single atoms is 0.1-5% of the mass of the single-atom catalyst.

[0010] 3. The preparation method of the single-atom catalyst for activating peroxymonosulfate according to claim 1, characterized in that it includes the following steps:

[0011] S1. Mix and fully grind an amino organic compound and an organic acid ligand in a mortar, calcine, wash with water, and dry to obtain a carrier;

[0012] S2. Add the carrier to a mixed liquid system of a cobalt salt solution and a chelating agent, heat and stir until the liquid is completely evaporated to obtain a solid;

[0013] S3. Grind the solid and heat it in a nitrogen atmosphere to obtain the single-atom catalyst for activating peroxymonosulfate.

[0014] 4. The preparation method according to claim 3, characterized in that in step S1, the amino organic compound is urea; the organic acid ligand is acetic acid dihydrate; the calcination is carried out in a muffle furnace; the calcination temperature is 400-500 °C; the calcination time is 2 h; the detergent is ultrapure water, and the obtained mixture is vacuum-dried at 80 °C for 12 h after washing.

[0015] 5. The preparation method according to claim 3, characterized in that in step S2, the cobalt salt solution is cobalt acetate; the chelating agent is 1,10-phenanthroline; the heating temperature is 50-80 °C; the heating time is 4-5 h.

[0016] 6. The preparation method according to claim 3, wherein in step S3, the heating is carried out under nitrogen, the heating rate during the heating process is 5-10 °C / min; the heating temperature is 500-600 °C; the pyrolysis time is 1-3 h.

[0017] 7. A single-atom catalyst for activating persulfate, which is prepared by the preparation method according to any one of claims 3 to 6.

[0018] 8. The application of the single-atom catalyst for activating persulfate according to any one of claims 1 to 2 or the single-atom catalyst for activating persulfate obtained by the preparation method according to any one of claims 3 to 8 in the degradation of organic wastewater.

[0019] 9. The application according to claim 1, which is characterized by comprising the following steps: mixing the single-atom catalyst, persulfate and organic wastewater for catalytic reaction to complete the removal of organic pollutants in the wastewater.

[0020] 10. The application according to claim 9, wherein the addition amount of the single-atom catalyst is 0.1 g of the single-atom catalyst added per liter of the organic wastewater; the concentration of persulfate in the catalytic reaction system is 0.4 mM; the organic pollutant in the wastewater is phenol; the phenol concentration is 2-15 mg L -1 ; the catalytic reaction is carried out under stirring conditions; the rotation speed of the stirring is 200-500 r / min; the temperature of the system is controlled at 15-30 °C during the catalytic reaction; the catalytic reaction time is 10-30 min.

[0021] Compared with the prior art, the advantages of the present invention are as follows:

[0022] 1. The present invention provides a preparation method and application of a novel single-atom catalyst for activating peroxymonosulfate. By introducing two heteroatoms (nitrogen and oxygen) into the graphene lattice, strong chemical bonds are formed with metal cobalt atoms, effectively anchoring the metal single atoms, preventing their migration and aggregation, and significantly enhancing the stability of the metal cobalt atoms. The single-atom catalyst maintains high degradation performance in a wide pH range (3-11), completely removes phenol in 15 min, and maintains 100% degradation efficiency in a continuous flow operation experiment for up to 240 h, showing excellent catalytic activity and durability.

[0023] 2. The present invention provides a preparation method and application of a novel single-atom catalyst for activating peroxymonosulfate. By doping heteroatoms in graphene with double atoms, the electronic structure and coordination environment of metal atoms can be precisely regulated. When activating persulfate, it is mainly converted into singlet oxygen ( 1 O2), 1O2 has good selectivity and anti-interference ability, which enables the single-atom catalyst provided by the present invention to have excellent selectivity and anti-interference performance when degrading organic pollutants. Common inorganic anions (Cl - , CO3 2- , H2PO4 - , SO4 2- ) and humic acid have no significant effect on the degradation ability of the catalyst. The single-atom catalyst can effectively decompose phenol, nitrobenzene, methylphenol and chlorophenol, showing a preferential activity towards electron-rich phenolic pollutants.

[0024] 3. The present invention provides a preparation method and application of a novel single-atom catalyst for activating peroxymonosulfate. The set temperature during the raw material calcination process is relatively low, the energy consumption is low, the equipment required for the whole reaction is simple, there is no need to adjust the pH, the operability is strong, the management and maintenance are convenient, it is easy to be industrially applied, can be used for the large-scale production of photocatalysts, is less affected by water quality conditions, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] Figure 1 It is the X-ray diffraction spectrum, Fourier transform infrared spectrum and the result of X-ray photoelectron spectrum of N1s of the support O-g-C3N4 and single-atom catalysts with different cobalt addition amounts (NO-GC, 6-Co-NO-GC and 20-Co-NO-GC) in Example 1 of the present invention;

[0027] Figure 2 It is the result of the influence of different metal doping amounts, different pH values, different inorganic anions and humic acid, and different phenolic pollutants on the degradation efficiency of phenol by the single-atom catalyst in Example 2 of the present invention;

[0028] Figure 3 It is the result of the radical quenching experiment of the single-atom catalyst 20-Co-NO-GC in the reaction system in Example 3 of the present invention;

[0029] Figure 4 It is the long-term operation experiment result of the single-atom catalyst 20-Co-NO-GC in the reaction system in Example 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The following further describes the present invention with reference to specific preferred embodiments, but does not limit the protection scope of the present invention thereby.

[0031] Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0032] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0033] Example

[0034] The materials and instruments used in the following examples are all commercially available.

[0035] Example 1:

[0036] A preparation method and application of a single-atom catalyst for activating peroxymonosulfate, the preparation method comprising the following steps:

[0037] (1) Preparation of the support: Urea (10 g) and oxalic acid dihydrate (5.5 g) are mixed and thoroughly ground in a mortar. The mixture is transferred to a covered crucible and then heated in a muffle furnace at a heating rate of 5 °C / min to 500 °C and calcined at 500 °C for 2 h. The obtained sample is finely ground and washed several times with deionized water to remove any possible impurities. Finally, the powder is dried in a vacuum drying oven at 80 °C for 12 h and ground to obtain the support O-g-C3N4.

[0038] (2) Preparation of the single-atom catalyst: Cobalt acetate (X mg) and 1,10-phenanthroline (100 mg) are dissolved in 5 mL of ethanol. Then 600 mg of O-g-C3N4 is added and heated at 60 °C for 4 h. The mixture is stirred in air at 80 °C until the solution is completely evaporated. The obtained solid is ground and transferred to a porcelain boat, heated to 600 °C at a rate of 10 °C / min under nitrogen conditions and held for 2 h. Finally, the furnace is allowed to cool naturally. The obtained product is denoted as X-Co-NO-GC, where X represents the content of cobalt acetate. NO-GC is prepared using the same steps as above except that Co acetate is not added.

[0039] Figure 1X-ray diffraction patterns, Fourier transform infrared spectra, and X-ray photoelectron spectra of N 1s for the support O-g-C3N4 and single-atom catalysts with different cobalt loadings (NO-GC, 6-Co-NO-GC, and 20-Co-NO-GC) in Example 1 of the present invention. In the figure, a is the comparison result of the X-ray diffraction patterns of the support O-g-C3N4 and single-atom catalysts with different cobalt loadings (NO-GC, 6-Co-NO-GC, and 20-Co-NO-GC), b is the comparison result of the Fourier transform infrared spectra of the support O-g-C3N4 and single-atom catalysts with different cobalt loadings (NO-GC, 6-Co-NO-GC, and 20-Co-NO-GC), and c is the comparison result of the X-ray photoelectron spectra of N 1s for the support O-g-C3N4 and single-atom catalysts with different cobalt loadings (NO-GC, 6-Co-NO-GC, and 20-Co-NO-GC).

[0040] As can be seen from Figure a: The introduction of nitrogen and Co did not significantly change the basic structure of the carbon support, and the characteristic peaks did not shift. Only one obvious carbon-related diffraction peak was observed, confirming the low Co loading. It is worth noting that as the Co content increased, the diffraction peak intensity gradually decreased, which may be due to the destruction of the planar units and the formation of a porous structure.

[0041] As can be seen from Figure b: X-Co-NO-GC maintained a similar structural integrity to O-g-C3N4. As the Co content increased, the peak intensity systematically decreased, indicating that the Co-C interaction was beneficial to the formation of amorphous carbon. An obvious spectral feature appeared at 2160 cm -1 -1, and its intensity increased with the increase of Co. This peak can be attributed to the co-induced surface defects, resulting in the formation of -CN (cyanide) functional groups and the development of sp 2 C-N bonds.

[0042] As can be seen from Figure c: The three peaks at 389, 399.1, and 400.1 eV belong to C-N=C, N-O, C-N-H, or N-(C)3, respectively. Among them, C-N=C is dominant and defines the main chain of O-g-C3N4. It is worth noting that the position and intensity of the peaks remained basically unchanged after co-doping, which was consistent with the results of the Fourier transform infrared spectra.

[0043] Example 2:

[0044] A preparation method and application of a single-atom catalyst for activating peroxymonosulfate, and the application method includes the following steps:

[0045] (1) Experiment on the effect of metal doping level on the degradation efficiency: In step (2) of Example 1, set X to 2, 10, 20, 40, 60, 80, 100 respectively to obtain single-atom catalysts with different Co doping levels. Add the obtained single-atom catalysts into 200 mL beakers respectively, and then add 50 mL of 10 mM phenol solution into the glass beakers. At room temperature (25 °C), mix them with a magnetic stirrer at a stirring speed of 360 r / min. Initiate the reaction by adding a certain amount of PMS and catalyst. The reaction time is 30 min. At predetermined time intervals, extract 1.0 mL of the sample and filter it into a liquid phase bottle through a polytetrafluoroethylene membrane (PTFE, 0.22 μm), and detect it using high-performance liquid chromatography (HPLC).

[0046] (2) Experiments on the effects of different pH, inorganic anions, humic acid, and phenolic compound types on degradation: The catalyst is 20-Co-NO-GC obtained in Example 1, the catalyst concentration is 0.1 g / L, the phenol concentration is 10 mM, the PMS concentration is 0.4 mM, the reaction temperature is 25 °C, the reaction time is 15 min, and the reactions are all carried out in 200 mL glass beakers and mixed at a magnetic stirring speed of 360 r / min. Use dilute hydrochloric acid and sodium hydroxide solution to adjust the solution pH to 1, 3, 5, 7, 9, 11, and set the first batch of experiments to obtain the degradation curves of phenol by 20-Co-NO-GC in different pH systems. Under other unchanged experimental conditions, with pH = 6.8, add Cl - , CO3 2- , H2PO4 - , SO4 2- and humic acid, and set the second batch of experiments to obtain the degradation curves of phenol by 20-Co-NO-GC in different inorganic anion and humic acid interference systems. Under other unchanged experimental conditions, with pH = 6.8 and the concentration of various pollutants being 2-CP, 3-CP, 4-CP, 2-MP, 3-MP, 4-MP, 2-NP, set the third batch of experiments to obtain the curves of 20-Co-NO-GC degrading different types of phenolic compounds.

[0047] Figure 2 are the results of the effects of different metal doping amounts, different pH, different inorganic anions, and different phenolic pollutants on the degradation efficiency of the single-atom catalyst for phenol in Example 2 of the present invention. Figure a is the curve of the single-atom catalyst with different metal doping amounts degrading phenol, Figure b is the curve of 20-Co-NO-GC degrading phenol in different pH systems, Figure c is the curve of 20-Co-NO-GC degrading phenol in different inorganic anion interference systems, and Figure d is the curve of 20-Co-NO-GC degrading different types of phenolic compounds.

[0048] As can be seen from Figure a: With the increase in the metal doping level, the degradation efficiency initially increased, but then decreased slightly. This trend can be attributed to two competing factors: insufficient active sites at low doping levels and metal aggregation into clusters at excessive doping levels, thereby reducing the proportion of catalytically active single-atom sites. When the Co doping amount was 20 mg, the catalyst exhibited the best degradation performance, achieving a phenol removal rate of 100 - 99% within 5 minutes. Therefore, 20-Co-NO-GC was selected as the representative catalyst for subsequent experiments.

[0049] As can be seen from Figure b: The catalyst maintained a high degradation performance within a wide pH range (3 - 11), completely removing phenol within 15 minutes, indicating the robustness of the active sites. Even under extremely acidic conditions (pH = 1), a degradation efficiency of >90% was still maintained within 15 minutes, indicating the excellent acid and alkali resistance of the catalytic sites.

[0050] As can be seen from Figure c: The presence of HA and all tested anions had no significant effect on the degradation of phenol, indicating that the PMS activated by 20-Co-NO-GC had strong resistance to interference from background organic and inorganic components in water. In traditional AOPs, the degradation efficiency of pollutants is often affected due to the scavenging effect of inorganic anions and HA on free radicals. However, this phenomenon was not observed in the 20-Co-NO-GC / PMS system, indicating that the reactive species responsible for degradation may be non-free radical entities.

[0051] As can be seen from Figure d: The selectivity of the PMS / Co-N-O-GC system for degrading various phenolic pollutants. Within just 10 minutes, the system could effectively decompose phenol, methylphenol, and chlorophenol in addition to nitrobenzene. This efficiency is mainly attributed to the fact that 1O2 is prone to accepting electrons from pollutants, especially those rich in electrons, although it shows limited activity towards electron-deficient substances such as nitrobenzene.

[0052] Example 3:

[0053] Preparation method and application of a single-atom catalyst for activating peroxymonosulfate. By radical quenching experiments, the role of reactive species in the reaction system was investigated:

[0054] (1) Free radical quenching experiment: Select the single-atom catalyst 20-Co-NO-GC / PMS that activates peroxymonosulfate with the best degradation effect as the research object. The catalyst concentration is 0.1 g / L, the phenol concentration is 10 mM, the PMS concentration is 0.4 mM, the reaction temperature is 25 °C, and the reaction is carried out in a 200 mL glass beaker and mixed at a magnetic stirring speed of 360 r / min. Add 5 mM tert-butanol (TBA), 0.5 mM p-benzoquinone (p-BQ), 5 mM methanol (MeOH), and 0.1 mM furfuryl alcohol (FFA) to the reaction vessel beaker respectively, and configure a standard reaction system without quenching agent as a blank control group. Take the PMS addition time as the 0 starting point of the reaction, and control the reaction time to 10 min. Among them, tert-butanol, p-benzoquinone, methanol, and furfuryl alcohol are the quenching agents of ·OH, ·O2 - , SO4 - , 1 O2 respectively. At predetermined time intervals, extract 1.0 mL of the sample and filter it into a liquid phase bottle through a polytetrafluoroethylene membrane (PTFE, 0.22 μm), and detect it using high performance liquid chromatography (HPLC).

[0055] Figure 3 This is the result of the free radical quenching experiment of the single-atom catalyst 20-Co-NO-GC in the reaction system in Example 3 of the present invention.

[0056] It can be seen from the figure that the inhibitory effects of excess methanol, tert-butanol, and p-benzoquinone on phenol removal are very small, indicating that ·OH, O2· - and SO4 - are not the main reactive oxygen species. The addition of furfural significantly inhibits the degradation of phenol, indicating that in the Co-NO-GC / PMS system, 1 O2 is the main active substance, which shows that the rapid degradation of phenol may be driven by a non-radical mechanism.

[0057] Example 4:

[0058] Preparation method and application of a single-atom catalyst for activating peroxymonosulfate. Through long-term operation experiments, investigate the stability of the catalyst in practical applications:

[0059] (1) Long-term operation experiment: When solving large-scale wastewater treatment problems, AOPs can continuously degrade pollutants using a dynamic column device, which is an ideal method to improve treatment efficiency while minimizing the system footprint. Therefore, the single-atom catalyst 20-Co-NO-GC / PMS, which has the best degradation effect on activating peroxymonosulfate, was selected as the research object, and a catalytic column device was constructed. The packing column was filled with a mixture of 25 mg of the catalyst and quartz sand to maintain the dispersion of the catalyst and improve its contact efficiency with pollutants. Absorbent cotton and filter paper were set at both ends of the column to prevent the quartz sand and the catalyst from being washed away by the wastewater. A peristaltic pump was used to introduce a phenol solution with a concentration of 1 mg L -1 , and a PMS concentration of 1 mM into the dynamic column at a flow rate of 0.3 mL min -1 . The treated effluent was collected by an autosampler at the outlet, and after passing through a 0.22 μm filter membrane, the residual phenol concentration was measured by high-performance liquid chromatography (HPLC). The device was operated for a total of 240 h.

[0060] Figure 4 This is the long-term operation experimental result of the single-atom catalyst 20-Co-NO-GC in the reaction system in Example 4 of the present invention.

[0061] As can be seen from the figure: The 20-Co-NO-GC packing column showed a strong continuous phenol removal ability, maintaining 100% efficiency during the 240-hour operation, thus demonstrating the high catalytic activity and durability of 20-Co-NO-GC. In contrast, the dynamic column without the 20-Co-NO-GC sample only showed marginal phenol removal efficiency, which may be attributed to the adsorption characteristics of quartz sand. These results confirm the practical application potential of the 20-Co-NO-GC sample in PMS-activated pollutant degradation. A cobalt ion leaching test was carried out on the treated wastewater, and the cobalt ion concentration was 0.13 mg L -1 , which meets the current national discharge standard (GB25467-2010). This finding further confirms the practical feasibility of the 20-Co-NO-GC catalyst in wastewater treatment applications.

[0062] The above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention still fall within the scope of the protection of the technical solution of the present invention.

Claims

1. A method for preparing a single-atom catalyst for activating peroxymonosulfate and its application, characterized in that: The invention comprises a carrier and cobalt single atoms loaded on the carrier; the carrier is an oxygen-doped graphite phase carbon nitride nanosheet; and the cobalt single atoms exist on the carrier in a well-dispersed single atom structure.

2. The single atom catalyst according to claim 1, characterized in that The mass of the cobalt single atom is 0.1-5% of the mass of the single atom catalyst.

3. The method for preparing the single-atom catalyst of activated peroxymonosulfate according to claim 1, characterized in that: The following steps are involved: S1. Mixing the amino organic matter and the organic acid ligand in a mortar and completely grinding them, calcining, washing with water, and drying to obtain a carrier; S2, adding the carrier to a mixed liquid system of a cobalt salt solution and a chelating agent, heating and stirring until the liquid is completely evaporated to obtain a solid; S3. Grinding the solid and heating it in a nitrogen atmosphere to obtain the activated peroxymonosulfate single atom catalyst.

4. The preparation method according to claim 3, characterized in that: In step S1, the amino organic matter is urea; the organic acid ligand is acetic acid dihydrate; the calcination is carried out in a muffle furnace; the calcination temperature is 400-500°C; the calcination time is 2h; the detergent is ultrapure water, and the mixture obtained after washing is vacuum dried at 80°C for 12h.

5. The preparation method according to claim 3, characterized in that: In step S2, the cobalt salt solution is cobalt acetate; the chelating agent is 1,10-phenanthroline; the heating temperature is 50-80° C.; and the heating time is 4-5 hours.

6. The preparation method according to claim 3, characterized in that: In step S3, the heating is carried out under nitrogen conditions, the heating rate during the heating process is 5-10°C / min; the heating temperature is 500-600°C; and the pyrolysis time is 1-3h.

7. A single-atom catalyst for activated persulfate, prepared by the preparation method according to any one of claims 3 to 6.

8. Use of the activated persulfate single-atom catalyst according to any one of claims 1 to 2 or the activated persulfate single-atom catalyst obtained by the preparation method according to any one of claims 3 to 8 in degrading organic wastewater.

9. The use according to claim 1, characterized in that: The method comprises the following steps: mixing a single-atom catalyst, permonosulfate and organic wastewater to carry out a catalytic reaction, thereby completing the removal of organic pollutants in the wastewater.

10. The use according to claim 9, characterized in that: The amount of the single-atom catalyst added is 0.1 g per liter of the organic wastewater; the concentration of permonosulfate in the catalytic reaction system is 0.4 mM; the organic pollutant in the wastewater is phenol; the phenol concentration is 2 to 15 mg L -1 ; The catalytic reaction is carried out under stirring conditions; the stirring speed is 200-500r / min; the temperature of the system is controlled at 15-30°C during the catalytic reaction; the catalytic reaction time is 10-30min.

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