A nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst, its preparation method and application

Abstract

This invention discloses a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst, its preparation method, and its application. This invention utilizes a pyrimidine-based ligand-derived nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst to activate a method for the degradation of bisphenol A in water by persulfate. This method possesses advantages such as strong resistance to water quality interference, high degradation efficiency, and environmental friendliness. It can efficiently remove organic pollutants from water, has high practical value, and promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control technology, specifically relating to a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst, its preparation method, and its application. Background Technology

[0002] Phenolic organic pollutants in industrial wastewater pose a significant environmental hazard, making the development of economical and efficient methods or processes for their removal urgent. Traditional technologies employ physical methods such as distillation, adsorption, and liquid-liquid extraction to treat phenolic wastewater, which incurs high application costs and energy consumption. Therefore, there is an urgent need to develop efficient, stable, environmentally friendly, and feasible technologies for removing phenolic pollutants from industrial wastewater.

[0003] Catalysis is considered one of the effective methods for treating organic pollutants. The catalysts used fall into two main categories: homogeneous and heterogeneous catalysts. In recent years, persulfate-based advanced oxidation technology has been widely used to treat recalcitrant toxic organic compounds in water. Compared to traditional Fenton and Fenton-like technologies, this technology has advantages such as high efficiency, wide pH range, and multiple activation pathways. Both homogeneous and heterogeneous catalysts can activate persulfate. However, homogeneous catalysts still face bottlenecks such as large dosage, difficulty in recovery, and susceptibility to secondary pollution. Heterogeneous catalysts for persulfate activation show advantages in overcoming these bottlenecks. However, issues such as the structural design and surface active site construction of heterogeneous catalysts limit their further development.

[0004] Single-atom catalysts combine the advantages of both homogeneous and heterogeneous catalysts. Their near-100% atom utilization and unique catalytic performance have led to their widespread application in energy and environmental catalysis. Nitrogen-doped carbon framework-anchored single-atom catalysts can not only effectively promote the adsorption of persulfate on their surfaces but also maximize the exposure of active sites to activate persulfate, thereby enhancing its potential for multi-pathway degradation of phenolic organic pollutants. Therefore, it is necessary to rationally design efficient and non-toxic single-atom catalysts for the degradation of phenolic organic pollutants. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0009] Dissolve 0.5–1.5 g of SBA-15 in 10–40 mL of a mixed solvent containing 0.5–1.5 g of acetylacetone iron, and stir continuously to obtain solution A;

[0010] 0.5–1 g of 4-hydroxy-6-methylpyrimidinyl ligand was added to solution A. After the reaction in an oil bath, the product was successively evaporated to dryness, vacuum dried, and ground to obtain the Fe(MHPD)@SBA-15 precursor.

[0011] The Fe(MHPD)@SBA-15 precursor was calcined in a nitrogen atmosphere and then subjected to acid washing, centrifugation, washing, vacuum drying, and grinding under reflux conditions to obtain a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst derived from pyrimidine ligands.

[0012] In a preferred embodiment of the preparation method of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the mixed solvent is a mixture of water and ethanol in a volume ratio of 0.5-1.5:0.5-1.5.

[0013] In a preferred embodiment of the preparation method of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the oil bath reaction is wherein the oil bath temperature is 50-100°C and the oil bath time is 24-36 h.

[0014] In a preferred embodiment of the preparation method of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the vacuum drying temperature is 60-80°C.

[0015] In a preferred embodiment of the preparation method of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the calcination is carried out at a temperature of 600–1000 °C for 5–10 h and at a heating rate of 1–5 °C / min.

[0016] In a preferred embodiment of the preparation method of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the acid washing temperature is 80-100°C and the washing time is 12-48 h.

[0017] In a preferred embodiment of the preparation method of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the acid washing solution is sulfuric acid with a concentration of 1-4 mol / L; the mass-volume ratio of Fe(MHPD)@SBA-15 precursor to sulfuric acid solution is 0.5-1.5:100.

[0018] The purpose of this invention is to overcome the shortcomings of the prior art and provide a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst.

[0019] The purpose of this invention is to overcome the shortcomings of the prior art and provide an application of a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst in the degradation of organic pollutants.

[0020] As a preferred embodiment of the application of the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst of the present invention, the single-atom catalyst is mixed with a solution containing organic pollutants, and persulfate is added to react and degrade the organic pollutant bisphenol A in the solution.

[0021] The catalyst has a mass of 5-10 mg, the persulfate has a concentration of 1-2 mmol / L, and the organic pollutant bisphenol A has a concentration of 5-10 ppm.

[0022] Beneficial effects of this invention:

[0023] (1) This invention utilizes the activation effect of nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst derived from pyrimidine ligands to activate persulfate, thereby generating a highly active substance - singlet oxygen, and then constructing a degradation catalytic system with singlet oxygen as the main reaction, ultimately achieving efficient degradation of bisphenol A in water.

[0024] (2) The single-atom catalyst prepared by the present invention has abundant catalytic active sites. Since iron is in the form of a single atom, it can significantly improve the utilization efficiency of atoms, thereby significantly increasing the yield of singlet oxygen in the reaction system. Therefore, it has excellent degradation effect on a variety of pollutants, and the reaction time is short. It also shows excellent resistance to water quality interference, has a wide applicable pH range, and has a strong resistance to organic anions in water. Therefore, it is very beneficial for the efficient removal of bisphenol A.

[0025] (3) In this invention, the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst derived from pyrimidine ligands is used with SBA-15 mesoporous material as template, which greatly improves the yield of the catalyst; acetylacetone iron is stable and does not easily agglomerate. 4-hydroxy-6-methylpyrimidine is used as a ligand because it has low toxicity and high N, which can effectively fix iron single atoms. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0027] Figure 1 The image shows a transmission electron microscope (TEM) image of the single-atom catalyst prepared in Example 1 of this invention.

[0028] Figure 2 The image shows the XRD pattern of the single-atom catalyst prepared in Example 1 of this invention.

[0029] Figure 3 The images show the Fourier transform (FT) EXAFS spectra of the single-atom catalyst prepared in Example 1 of this invention, as well as Fe foil, FeO, Fe2O3, Fe3O4, and FePC on the Fe-K side.

[0030] Figure 4 The image shows the effect of the single-atom catalyst prepared in Example 1 of this invention on the degradation of bisphenol A by persulfate under different pH conditions.

[0031] Figure 5 The image shows the effect of the single-atom catalyst prepared in Example 1 of this invention activating persulfate to degrade bisphenol A under different ion interference conditions.

[0032] Figure 6 The diagram shows the effect of the single-atom catalyst prepared in Example 1 of this invention on the degradation of bisphenol A by persulfate under different water quality conditions.

[0033] Figure 7 This is a diagram showing the cyclic degradation effect of the single-atom catalyst prepared in Example 1 of the present invention.

[0034] Figure 8 The diagram shows the effect of the single-atom catalyst prepared in Example 1 of this invention on the degradation of bisphenol A by persulfate with different catalysts. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0038] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0039] The adsorption performance of the material obtained in this embodiment of the invention was tested according to the following method:

[0040] A 50 mL solution of 10 ppm bisphenol A was added to a 100 mL beaker, along with a pyrimidine-ligand-derived nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst (Fe1 / NC@SBA15) and persulfate (PMS). The dosages of Fe1 / NC@SBA15 and PMS in the reaction system were 0.2 g / L and 1 mmol / L, respectively. The reaction was carried out on a magnetic stirrer for 1 h to allow for the adsorption of bisphenol A.

[0041] The yield of the material obtained by this invention is calculated according to the following formula:

[0042] Yield (%) = Mass of final catalyst / Amount of precursor × 100%.

[0043] Example 1

[0044] This embodiment provides a method for preparing a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst, specifically as follows:

[0045] Synthesis of Fe(MHPD)@SBA-15 precursor: First, 1.06 g of acetylacetone iron Fe(acac)3 was dispersed and dissolved in 20 mL of a mixed solvent (deionized water and ethanol = 1:1) to obtain an orange-red solution A. Then, 1.00 g of SBA-15 was added and stirred vigorously until completely dissolved. Next, 0.99 g of 4-hydroxy-6-methylpyrimidine (MHPD) was added, and stirring continued for 1 h. The mixture was then poured into a 100 mL round-bottom flask and heated under reflux in an oil bath at 80 °C for 24 h. Finally, the temperature was raised to 100 °C to evaporate the solvent, and the sample was dried under vacuum to obtain an orange powder Fe(MHPD)@SBA-15 precursor sample.

[0046] Synthesis of Fe1 / NC@SBA15: 1 g of orange powder was placed in a 50 mL covered ceramic boat, then transferred to a tube furnace and heated to 900 °C at a heating rate of 2 °C / min under N2 atmosphere and held for 2 h. After natural cooling to room temperature, a black solid powder was obtained. The obtained sample was dispersed in 100 mL of 2 mol / L H2SO4 and heated under reflux at 80 °C for 24 h to remove Fe and its oxides from the sample surface. Finally, Fe1 / NC@SBA15 was obtained by centrifugation, washing with water, and vacuum drying.

[0047] Figure 1 These are transmission electron microscopy (TEM) images of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 at different magnifications. Figure 1 It can be seen that no Fe particles were found in the high-resolution transmission electron microscopy of Fe1 / NC@SBA15 and it exhibited an amorphous structure.

[0048] Figure 2 The image shows the XRD pattern of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1. Figure 2 It can be seen that the broad X-ray diffraction peak appearing at around 22° in the XRD pattern can be attributed to amorphous silicon dioxide, and no diffraction peaks of other elements are present, indicating that Fe is uniformly dispersed in the carbon framework.

[0049] Figure 3 The images show the Fourier transform (FT) EXAFS spectra of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1, as well as Fe foil, FeO, Fe2O3, Fe3O4, and FePC on the Fe-K edge. Figure 3 It can be seen that the single-atom Fe is anchored by the nitrogen-oxygen co-doped carbon framework.

[0050] These results indicate that the material before acid washing contains both iron single atoms and clusters. Acid washing removes the clusters, leaving the iron single atoms. A pyrimidine-based ligand-derived nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst (Fe1 / NC@SBA15) of this invention has been successfully prepared.

[0051] Figure 4 This image shows the effect of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 of this invention on the activation of persulfate degradation of bisphenol A under different pH conditions. Figure 4 It was found that the prepared single-atom catalyst (Fe1 / NC@SBA15) had no effect on the degradation efficiency of bisphenol A at pH 2, 4, 6, and 8, and the degradation rate reached 100% within 30 min. At pH 10, the removal rate of bisphenol A also reached 94%, while at pH 12, the removal rate was only 48%. These results indicate that the pyrimidine-based ligand-derived nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 has a strong adaptability to acidic conditions, but its degradation effect is significantly inhibited under strongly alkaline conditions.

[0052] Figure 5 This image shows the effect of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 of this invention on the activation of persulfate for the degradation of bisphenol A under different ion interference conditions. Figure 5 It can be seen that when inorganic anions are added, the degradation efficiency of bisphenol A by the nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst (Fe1 / NC@SBA15) derived from pyrimidine ligands prepared in Example 1 is not inhibited, and the degradation rate still reaches 100% at 30 min.

[0053] Figure 6This image shows the effect of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 of this invention on the activation of persulfate degradation of bisphenol A under different water quality conditions. Figure 6 As can be seen, compared with the deionized water system, the single-atom catalyst (Fe1 / NC@SBA15) did not interfere with the degradation rate of bisphenol A in four actual water samples (tap water, Slender West Lake, Yangtze River, and campus lake), and the degradation rate was still 100% after 30 minutes, demonstrating high removal efficiency. This indicates that the Fe1 / NC@SBA15-PMS system constructed in this invention has better anti-interference ability.

[0054] Figure 7 This image shows the cyclic degradation effect of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 of this invention. Figure 7 It can be seen that after 5 cycles, the single-atom catalyst (Fe1 / NC@SBA15) still has a high and stable degradation efficiency for bisphenol A, with a removal efficiency of 100% in 30 minutes, indicating that the material has high stability.

[0055] Example 2

[0056] The difference between this embodiment and Example 1 is that the calcination temperature was adjusted from 900℃ to 600℃, while the rest of the preparation process was the same as in Example 1, and a single-atom catalyst was obtained.

[0057] Example 3

[0058] The difference between this embodiment and Example 1 is that the calcination temperature was adjusted from 900℃ to 1000℃, while the rest of the preparation process was the same as in Example 1, and a single-atom catalyst was obtained.

[0059] The performance of the single-atom catalysts prepared in the above examples was tested, and the results compared with those of Example 1 are shown in Table 1.

[0060] Table 1

[0061] Yield (%) Degradation efficiency (%) Example 1 79 100 Example 2 67 70 Example 3 53 90

[0062] As shown in Table 1, adjusting the calcination temperature has a significant impact on the performance of the single-atom catalyst. This is because pyrolysis temperature is a crucial factor in material synthesis, and an appropriate calcination temperature helps maintain the highly dispersed state of the single-atom catalyst, preventing it from agglomerating on the solid support. High calcination temperatures may lead to stronger interactions between the single atoms and the support, thereby reducing its dispersibility and affecting catalytic activity. Based on the results in the table above, the optimal technical effect is achieved when the calcination temperature in this invention is 900℃.

[0063] Example 4

[0064] The difference between this embodiment and Example 1 is that the oil bath temperature is adjusted to 50°C, while the rest of the preparation process is the same as in Example 1, resulting in a single-atom catalyst.

[0065] Example 5

[0066] The difference between this embodiment and Example 1 is that the oil bath temperature is adjusted to 100°C, while the rest of the preparation process is the same as in Example 1, and a single-atom catalyst is obtained.

[0067] The performance of the single-atom catalysts prepared in the above examples was tested, and the results compared with those of Example 1 are shown in Table 2.

[0068] Table 2

[0069] Yield (%) Degradation efficiency (%) Example 1 79 100 Example 5 60 60 Example 6 61 90

[0070] As shown in Table 2, adjusting the oil bath temperature has a significant impact on the performance of the single-atom catalyst. This is because the oil bath promotes the catalyst activation process, and an appropriate oil bath temperature facilitates the interaction between the catalyst and the support, promoting the formation of active sites and improving surface reactivity, thereby affecting the catalytic effect. Excessive temperature may lead to the destruction of the catalyst structure or the deactivation of active sites, thus affecting the catalytic effect. Based on the results in the table above, the optimal technical effect can be obtained when the oil bath temperature in this invention is 80℃.

[0071] Example 6

[0072] The difference between this embodiment and Example 1 is that the 2 mol / L H2SO4 used for acid washing is changed to 1 mol / L H2SO4, while the rest of the preparation process is the same as in Example 1, and a single-atom catalyst is obtained.

[0073] Example 7

[0074] The difference between this embodiment and Example 1 is that the 2 mol / L H2SO4 used for acid washing is adjusted to 4 mol / L H2SO4, while the rest of the preparation process is the same as in Example 1, to obtain a single-atom catalyst.

[0075] The performance of the single-atom catalysts prepared in the above examples was tested, and the results compared with those of Example 1 are shown in Table 3.

[0076] Table 3

[0077]

[0078]

[0079] As shown in Table 3, adjusting the H2SO4 concentration during acid washing significantly affects the performance of the single-atom catalyst. This is because different concentrations of sulfuric acid have different washing capabilities. An appropriate concentration of sulfuric acid can effectively remove impurities and oxides from the surface of the single-atom catalyst, maintaining the cleanliness of the active sites and thus improving catalyst activity. Excessive acid concentration can lead to abnormal desorption or damage during the acid washing process, washing away the original single atoms. Conversely, too low a concentration will result in the presence of clusters in the material, affecting the catalytic effect. Based on the results in the table above, the optimal technical effect is achieved when the H2SO4 concentration during acid washing in this invention is 2M.

[0080] Example 8

[0081] The difference between this embodiment and Example 1 is that the ratio of water to ethanol in the mixed solvent is adjusted to 0.5:1.5, while the rest of the preparation process is the same as in Example 1, to obtain a single-atom catalyst.

[0082] Example 9

[0083] The difference between this embodiment and Example 1 is that the ratio of water to ethanol in the mixed solvent is adjusted to 1.5:0.5, while the rest of the preparation process is the same as in Example 1, to obtain a single-atom catalyst.

[0084] The performance of the single-atom catalysts prepared in the above examples was tested, and the results compared with those of Example 1 are shown in Table 4.

[0085] Table 4

[0086] Yield (%) Degradation efficiency (%) Example 1 79 100 Example 8 69 80 Example 9 67 85

[0087] As shown in Table 4, adjusting the ratio of water to ethanol significantly affects the performance of the single-atom catalyst. This is because changes in the water-to-ethanol ratio influence the solubility and dispersibility of the single-atom catalyst in the reaction system. An appropriate water-to-ethanol ratio helps maintain a highly dispersed state of the catalyst and improves its catalytic activity. An excessively high ratio leads to poor coordination, while an excessively low ratio results in insufficient dissolution of SBA-15. Based on the results in the table above, a water-to-ethanol ratio of 1:1 in this invention yields the best technical results.

[0088] Comparative Example 1

[0089] Commercial zero-valent iron powder

[0090] Comparative Example 2

[0091] The difference between this embodiment and Example 1 is that acetylacetone iron Fe(acac)3 is not added, but the rest of the preparation process is the same as in Example 1, and the catalyst is obtained.

[0092] Comparative Example 3

[0093] The difference between this embodiment and Example 1 is that 4-hydroxy-6-methylpyrimidine is not added; all other preparation processes are the same as in Example 1, and the catalyst is obtained.

[0094] Comparative Example 4

[0095] The difference between this embodiment and Example 1 is that 4-hydroxy-6-methylpyrimidine is not added, and an impregnation method is used to load the SBA15 with the same iron content as in Example 1.

[0096] The performance of the single-atom catalysts prepared in the above comparative examples was tested, and the results compared with those of Example 1 are shown in Table 5.

[0097] Table 5

[0098] Yield % Degradation efficiency % Example 1 79 100 Comparative Example 1 66 ＜1 Comparative Example 2 50 60 Comparative Example 3 47 ＜1 Comparative Example 4 73 ＜1

[0099] As can be seen from the table above, the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 not only has extremely high degradation efficiency but also high yield, which is in stark contrast to the other four comparative materials. This indicates that the roles of template SBA15, iron acetylacetone providing the iron source, and 4-hydroxy-6-methylpyrimidine providing the ligand are indispensable in the formation of the single-atom catalyst (Fe1 / NC@SBA15). At the same time, the comparison also shows that the degradation efficiency of the single-atom catalyst (Fe1 / NC@SBA15) is very high. Figure 8 The graph shows the effect of the single-atom catalyst (Fe1 / NC@SBA15) prepared in Example 1 on the degradation of bisphenol A by persulfate and different catalysts. The catalyst obtained in the comparative example has a much lower degradation performance than the nitrogen-oxygen doped carbon-anchored iron single-atom catalyst (Fe1 / NC@SBA15) derived from pyrimidine ligands. This also shows that the iron single-atom catalyst has the potential to efficiently activate persulfate to degrade bisphenol A.

[0100] In summary, this invention discloses a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst, its preparation method, and its applications. This invention utilizes a pyrimidine-ligand-derived nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst to activate a method for the degradation of bisphenol A in water by persulfate. This method possesses advantages such as strong resistance to water quality interference, high degradation efficiency, and environmental friendliness. It can efficiently remove organic pollutants from water, has high practical value, and promising application prospects.

[0101] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a nitrogen-oxygen-doped carbon-anchored iron monatomic catalyst, characterized in that: include, Dissolve 0.5~1.5 g of SBA-15 in 10~40 mL of a mixed solvent containing 0.5~1.5 g of ferric acetylacetone, and stir continuously to obtain solution A; 0.5~1 g of 4-hydroxy-6-methylpyrimidinyl ligand was added to solution A. After the oil bath reaction, the product was successively evaporated to dryness, vacuum dried, and ground to obtain Fe(MHPD)@SBA-15 precursor. The Fe(MHPD)@SBA-15 precursor was calcined in a nitrogen atmosphere and then subjected to acid washing, centrifugation, washing, vacuum drying and grinding under heating and reflux conditions to obtain a nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst derived from pyrimidine ligands. The calcination is carried out at a temperature of 600-1000℃, for a duration of 5-10 hours, and at a heating rate of 1-5℃ / min. The pickling temperature is 80~100℃, and the washing time is 12~48 h; The application of the nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst in the degradation of organic pollutants includes the following: after mixing the single-atom catalyst with a solution containing organic pollutants, persulfate is added to react and degrade the organic pollutant bisphenol A in the solution. The catalyst has a mass of 5-10 mg, the persulfate has a concentration of 1-2 mmol / L, and the organic pollutant bisphenol A has a concentration of 5-10 ppm.

2. The method of making a nitroxide-doped carbon-anchored iron monatomic catalyst of claim 1, wherein: The mixed solvent is a mixture of water and ethanol, with a volume ratio of 0.5~1.5:0.5~1.

5.

3. The method of producing a nitroxide-doped carbon-anchored iron- monatomic catalyst of claim 1, wherein: The oil bath reaction is carried out at a temperature of 50-100°C for 24-36 hours.

4. The method of making a nitroxide-doped carbon-anchored iron- monatomc catalyst of claim 1, wherein: The vacuum drying temperature is 60~80℃.

5. The method of making a nitroxide-doped carbon-anchored iron- monatomc catalyst of claim 1, wherein: The pickling solution used is sulfuric acid with a concentration of 1~4 mol / L; the mass-to-volume ratio of Fe(MHPD)@SBA-15 precursor to sulfuric acid solution is 0.5~1.5∶100.

6. A nitrogen-oxygen-doped carbon-anchored iron single-atom catalyst prepared by the preparation method according to any one of claims 1 to 5.

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