Preparation method and application of mesoporous structure nitrogen-doped carbon supported manganese monatomic catalyst

Abstract

This invention discloses a method for preparing and applying a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst. Using magnesium hydroxide as a template material, a synergistic strategy of manganese-phenanthroline complexation and stepwise calcination is employed to regulate the pore topology of the carbon support, thereby constructing a nitrogen-doped carbon-supported manganese single-atom catalyst rich in mesoporous structures in situ. This method improves the manganese atom loading while optimizing the spatial accessibility of active sites, thus increasing the activation efficiency of the catalyst per unit mass for the oxidant. It solves the problem of low active site utilization in macroporous catalysts obtained using heavy magnesium oxide templates in the past.

Description

Technical Field

[0001] This invention relates to the field of catalysts and wastewater treatment technology, specifically to a method for preparing and applying a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst. Background Technology

[0002] Currently, emerging pollutants such as tetrabromobisphenol A (TBBPA) pose a serious threat to aquatic environmental safety, and traditional wastewater treatment technologies are insufficient for their effective degradation. Heterogeneous advanced oxidation technologies, with persulfate activation at their core, are an effective means of degrading such pollutants. Among these, single-atom catalysts have attracted considerable attention due to their maximized atom utilization efficiency, well-defined active centers, and tunable electronic structures. The characteristic that each metal atom represents an active site ensures high dispersion and effective anchoring of active components, theoretically endowing the material with extremely high catalytic activity per unit mass. Among many transition metals, manganese is an ideal choice for single-atom catalysts due to its high catalytic activity, low environmental toxicity, abundant crustal reserves, and low cost. Nitrogen-coordinated manganese atoms (such as the Mn-N4 site) are the active centers for activating persulfate, promoting the generation of active species through atomic-level redox cycles.

[0003] However, existing manganese single-atom catalysts still face the following technical bottlenecks in practical applications: (1) Manganese atoms are prone to migration and aggregation during high-temperature pyrolysis, resulting in limited actual anchorable single-atom loading; (2) Traditional preparation methods often use heavy magnesium oxide as a hard template, resulting in carbon support channels dominated by macropores, lacking efficient mesoporous networks, and causing significant internal diffusion resistance of reactant molecules to the active centers within the channels. A large number of single-atom sites are buried inside the carbon matrix and cannot participate in the reaction, resulting in insufficient spatial accessibility of active sites; (3) Due to the dual constraints of site density and mass transfer efficiency, the activation efficiency of existing manganese single-atom catalysts for persulfate is low, requiring the addition of excessive oxidant to achieve effective degradation of pollutants, leading to high remediation costs. Therefore, there is an urgent need to develop a manganese single-atom catalyst with high metal loading, rich mesoporous structure, and high oxidant activation efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst. By controlling the pore topology of the carbon support, the manganese atom loading is increased while the spatial accessibility of the active sites is optimized, thereby improving the activation efficiency of the catalyst per unit mass for the oxidant and providing a material basis for reducing the cost of advanced oxidation water treatment.

[0005] This invention is achieved through the following technical solutions: A method for preparing a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst, the method comprising the following steps: (1) Precursor complexation and loading: Manganese salt, 1,10-phenanthroline or its derivatives and magnesium hydroxide are dispersed in an organic solvent, and then subjected to ultrasonic treatment and heating and stirring at 60~80℃. The organic solvent is then removed by rotary evaporation to obtain the pyrolytic precursor. (2) Stepwise calcination: The pyrolysis precursor obtained in step (1) is ground, sieved, and placed in a tube furnace. It is first calcined at 2~5 °C for 1 min under an oxygen-containing atmosphere. -1 The temperature is increased to 180~250 ℃ at a rate and then held for 30~60 min for low-temperature pre-oxidation treatment. Then, the temperature is switched to an inert protective atmosphere and increased to 600~650 ℃ at the same rate and held for 60~120 min for high-temperature carbonization treatment. After naturally cooling to room temperature, the product is taken out to obtain a black carbonized product. (3) Template washing and purification: The black carbonized product obtained in step (2) is dispersed in an inorganic acid solution, stirred and washed at 60~80℃, washed until neutral, dried and ground to obtain a black powdery mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst.

[0006] Preferably, in step (1), the manganese salt is selected from manganese acetate, manganese chloride, or manganese nitrate; the 1,10-phenanthroline derivative is selected from 3,4,7,8-tetramethyl-1,10-phenanthroline or 2,9-dimethyl-1,10-phenanthroline; and the organic solvent is one or more of methanol, ethanol, and acetonitrile.

[0007] Preferably, the molar ratio of manganese salt, 1,10-phenanthroline or its derivative to magnesium hydroxide in step (1) is 0.50 ~ 3.00:9.00:600, and the concentration of manganese salt is 0.0015-0.03 mol / L.

[0008] Preferably, the ultrasonic frequency in step (1) is 10~50 kHz, the ultrasonic time is 10~60 min, and the heating and stirring time is 6~12 h.

[0009] Preferably, the inorganic strong acid used for pickling in step (3) is one or more of hydrochloric acid, sulfuric acid, or nitric acid, with a concentration of 0.5~1.0 M and a pickling solid-liquid ratio of 5~10 g / L. -1 The pickling time is 4-8 hours.

[0010] This invention utilizes magnesium hydroxide to form lightweight magnesium oxide with small particle size and low bulk density in situ during high-temperature carbonization at 600~650 ℃. This not only acts as a hard template agent during the high-temperature pyrolysis of organic matter and metal precursors, but also constructs densely distributed mesoporous channels in situ. This structure provides a high specific surface area anchoring support for manganese-nitrogen coordination precursors, inhibiting the surface migration and aggregation of manganese single atoms during pyrolysis. At the same time, the mesoporous channels also have a confinement effect on manganese single atoms, thereby significantly improving the catalyst's activation efficiency for persulfate and its ability to oxidize and degrade new pollutants.

[0011] Therefore, a second objective of this invention is to protect the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared by the above method. The catalyst support has a rich mesoporous structure, and the manganese element loading can reach up to 4.62 wt%, and is highly dispersed in the form of single atoms.

[0012] A third objective of this invention is to provide the application of the catalyst in the degradation of novel pollutants in wastewater using a persulfate-based advanced oxidation system, including adding the catalyst and persulfate to the wastewater to be treated. The catalyst dosage is 0.02~0.20 g / L. -1 Under conditions where the persulfate concentration is 0.1–2.0 mM and the wastewater pH range is 3.0–11.0, the catalyst achieves an activation efficiency of 43.1% for persulfate, a degradation efficiency of 100% for new pollutants, and a metal leaching amount of less than 20 μg / L. -1 .

[0013] Alternatively, a catalytic membrane prepared from a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst can be placed in a continuous flow reactor to treat water containing new pollutants. The concentration of the new pollutant in the influent is 1 mg / L. -1 Under conditions of persulfate concentration of 0.1 mM, the system maintained an effluent pollutant removal efficiency of over 99.5% for 24 hours of continuous operation, with no obvious damage or catalyst shedding on the membrane module surface.

[0014] The new contaminant includes at least one of tetrabromobisphenol A (TBBPA), bisphenol A (BPA), phenol, sulfamethoxazole (SMX), and chlorobenzene (4-CP). The persulfate is a permonosulfate or a perdisulfate.

[0015] The catalytic membrane is prepared as follows: the obtained mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst is mixed with polyacrylonitrile (PAN) and the catalytic membrane is prepared by electrospinning. Specifically, the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst is dispersed in a dimethylformamide (DMF) solution containing polyacrylonitrile (PAN), and an appropriate amount of acetone is added to adjust the evaporation rate. After stirring, a homogeneous casting solution is formed. Then, the casting solution is transferred to an electrospinning device, sprayed into filaments under the action of a high-voltage electric field, solidified on a receiving roller, and dried to obtain a self-supporting catalytic membrane. The casting solution preparation process is as follows: 10-20 g of polyacrylonitrile (PAN) is dissolved in 50-100 mL of dimethylformamide (DMF) to obtain solution A; 5-10 mL of DMF and 5-10 mL of acetone are mixed to obtain solution B; 150-300 mg of catalyst, 5-10 mL of DMF and 5-10 mL of acetone are mixed to obtain solution C; solutions A, B and C are mixed at a volume ratio of 4:1:1 and stirred for 6-12 h to form the casting solution.

[0016] Preferably, the continuous flow reaction device includes an influent system, a membrane reaction unit, and an effluent collection system. The water containing organic pollutants to be treated is premixed with a persulfate solution and flows at a constant flow rate through the membrane reaction unit filled with the catalytic membrane, completing the catalytic oxidation degradation process within a set hydraulic residence time.

[0017] The beneficial effects of this invention are as follows: (1) Enhanced mass transfer through mesoporous structure significantly improves oxidant activation efficiency: This invention uses magnesium hydroxide and employs a synergistic strategy of manganese-phenanthroline complexation and stepwise calcination to regulate the pore topology of the carbon support, constructing a densely distributed mesoporous structure in situ. This significantly shortens the diffusion path of oxidant and pollutant molecules to the manganese single-atom sites inside the pores, solving the problem of low active site utilization in traditional macroporous catalysts obtained using heavy magnesium oxide templates. Under the same conditions, the catalyst of this invention achieves an activation efficiency of 43.1% for persulfate, which is 3.3 times higher than that of catalysts obtained using traditional heavy magnesium oxide templates (13.2%); the degradation efficiency for the target new pollutant reaches 100%, which is superior to the 23.1~60.5% of traditional heavy magnesium oxide template catalysts. The improved activation efficiency can directly reduce the amount of oxidant added, thus lowering the remediation cost.

[0018] (2) Achieving high loading and highly dispersed manganese metal loading, combining performance and economic advantages. This invention utilizes the spatial confinement effect of light magnesium oxide with small particle size and low bulk density formed in situ during the high-temperature carbonization of the precursor by magnesium hydroxide at 600~650 ℃, effectively suppressing the migration and aggregation of manganese atoms during high-temperature pyrolysis, achieving a highly dispersed single-atom loading of up to 4.62 wt%. At the same time, manganese metal is abundant in the earth's crust, inexpensive, and cost-controllable. The overall preparation process is highly repeatable and suitable for large-scale production, overcoming the bottleneck of high cost and difficulty in promotion of precious metal single-atom catalysts.

[0019] In summary, this invention uses magnesium hydroxide as a template material and employs a synergistic strategy of manganese-phenanthroline complexation and stepwise calcination to regulate the pore topology of the carbon support, thereby constructing a nitrogen-doped carbon-supported manganese single-atom catalyst rich in mesoporous structures in situ. This improves the manganese atom loading while optimizing the spatial accessibility of active sites, thus increasing the activation efficiency of the catalyst per unit mass for the oxidant. This solves the problem of low active site utilization in macroporous catalysts obtained using heavy magnesium oxide templates in the past. Attached Figure Description

[0020] Figure 1 This is a comparison chart of the metal loading of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalysts prepared in Examples 1-3 and the catalysts prepared in Comparative Examples 1-2.

[0021] Figure 2 Transmission electron microscopy (TEM) images (b) of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1 (a) and the macroporous manganese single-atom catalyst prepared in Comparative Example 1.

[0022] Figure 3 The images show aberration-corrected high-angle annular dark-field scanning transmission electron microscope (AC-HAADF-STEM) images (left) and elemental mapping images (right) of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1.

[0023] Figure 4 The figure (b) shows a comparison of the nitrogen adsorption-desorption isotherm (a) and pore size distribution curve of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1 and the macroporous manganese single-atom catalyst prepared in Comparative Example 1.

[0024] Figure 5 The image shows the manganese 2p orbital spectrum of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1.

[0025] Figure 6The graph shows a comparison of the activation performance (a) of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1 and the macroporous manganese single-atom catalyst prepared in Comparative Example 1 on persulfate and the degradation performance (b) of new pollutants.

[0026] Figure 7 The effects of initial pH, anions, and dissolved organic matter on the activation of persulfate degradation of tetrabromobisphenol A by the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1.

[0027] Figure 8 The results are from the quenching experiment of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1 for the degradation of tetrabromobisphenol A by persulfate.

[0028] Figure 9 The recycling performance (a) and metal leaching performance (b) of the mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared in Example 1 are shown.

[0029] Figure 10 Scanning electron microscope (SEM) image (a) of the nitrogen-doped carbon-supported manganese single-atom catalytic membrane with a mesoporous structure in Example 6 and its application performance in a continuous flow reactor (b). Detailed Implementation

[0030] The following is a further description of the invention, but not a limitation thereof.

[0031] Example 1: 1) Dissolve 3.0 mmol manganese acetate and 9.0 mmol 1,10-phenanthroline in 100 mL of ethanol and sonicate for 30 min. Then add 600 mmol magnesium hydroxide and sonicate for 30 min. Stir the mixture in an oil bath at 80 °C for 8 h. Then remove the ethanol by rotary evaporation to obtain the pyrolysis precursor. 2) Grind and sieve the precursor (100 mesh). Place the sieved powder in a quartz boat in a tube furnace and incubate in air at 2 °C for 1 minute. -1 The temperature was increased to 180 °C at a set heating rate, held for 30 min, and then increased at 2 °C / min under nitrogen atmosphere. -1 Heat to 600 °C at the set heating rate, hold for 120 min, and then cool to room temperature. 3) Grind and sieve the cooled black solid, weigh 5 g of the black solid and mix it with 500 mL of 1.0 M sulfuric acid solution. Mix at 80 °C for 8 h. Wash the remaining acid-washed solid until neutral, then dry and grind it to obtain a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst, named Mn-NC-Meso.

[0032] The metallicity of Mn-NC-Meso is as follows Figure 1 As shown, the transmission electron microscope image is as follows: Figure 2 As shown, the spherical aberration electron micrograph and mapping diagram are as follows: Figure 3 As shown, the nitrogen adsorption-desorption isotherms and pore size distribution curves are as follows: Figure 4 As shown, the Mn 2p XPS spectrum is as follows: Figure 5 As shown, the Mn-NC-Meso catalyst contains 4.62 wt% manganese and possesses a rich mesoporous structure. The surface manganese is dispersed at the atomic level, and no nanoparticles or clusters of manganese were observed. Furthermore, manganese, carbon, nitrogen, and oxygen are uniformly distributed on the catalyst surface. The BET specific surface area of ​​Mn-NC-Meso is 589.3 m². 2 g -1 Mesopores (2~50 nm) account for 71.6% of the total pore volume. The high-resolution Mn 2p spectrum of Mn-NC-Meso is shown below. Figure 5 As shown, three characteristic peaks are observed at 641.65, 646.45, and 653.35 eV, corresponding to Mn(II), Mn(III), and Mn(Ⅳ), respectively, indicating that the Mn single atom is in a high oxidation state.

[0033] Example 2: Compared to Example 1, the difference lies in the amount of manganese acetate used, which is 0.5 mmol. The resulting manganese catalyst was named Mn-NC-1, and the metal loading of Mn-NC-1 is as follows... Figure 1 As shown, the manganese content is 0.83 wt%; only manganese single-atom structures exist on the surface.

[0034] Example 3: Compared to Example 1, the difference lies in the amount of manganese acetate used, which is 1.0 mmol. The resulting manganese catalyst was named Mn-NC-2, and the metal loading of Mn-NC-2 is as follows... Figure 1 As shown, the manganese content is 1.78 wt%; only manganese single-atom structures exist on the surface.

[0035] Comparative Example 1: Referring to Example 1, the difference lies in replacing magnesium hydroxide with an equimolar amount of heavy magnesium oxide to obtain a macroporous manganese single-atom catalyst, named Mn-NC-Macro. The metal loading of Mn-NC-Macro is as follows... Figure 1 As shown, the transmission electron microscope image is as follows: Figure 2 As shown, the nitrogen adsorption-desorption isotherms and pore size distribution curves are as follows: Figure 4 As shown in the figure. The results show that the metal loading of Mn-NC-Macro is 4.17 wt%, the pore structure is dominated by macropores, and the mesopore content is 28.5%, which is significantly lower than the mesopore content of 71.6% of Mn-NC-Meso obtained in Example 1.

[0036] Comparative Example 2: Compared to Example 1, the difference lies in the amount of manganese acetate used, which is 6.0 mmol. The resulting manganese catalyst was named Mn-NC-4, and the metal loading of Mn-NC-4 is as follows... Figure 1 As shown, the manganese content is 9.12 wt%; the surface contains both single manganese atoms and manganese clusters.

[0037] Application Example 1: The degradation experiment was conducted in a 100 mL container with shaking at 25 °C and 150 rpm. 10 mg of Mn-NC-Meso prepared in Example 1 or Mn-NC-Macro prepared in Comparative Example 1 was added to 50 mL of a 10 mg L⁻¹ solution. -1 A solution of tetrabromobisphenol A or other new contaminants (bisphenol A, chlorobenzene, phenol, and sulfamethoxazole, etc.) (at which point the concentration of Mn-NC-Meso or Mn-NC-Macro catalyst is 0.20 g / L) -1 The catalyst was uniformly dispersed by sonication for 30 seconds (pH 7.0). Then, 0.5 mL of 100 mM sodium persulfate (PDS) solution (PDS concentration 1 mM) was added to the above solution to mark the start of the degradation reaction. Samples were taken from the reaction solution at 0, 5, 10, 15, 20, 25, and 30 min. The samples were filtered through a 0.22 μm aqueous filter, and the concentrations of tetrabromobisphenol A or other new pollutants were detected by high-performance liquid chromatography (HPLC) or HPLC-MS / MS. All experiments were performed in triplicate, and the results are expressed as averages. The removal efficiency of the new pollutants was calculated.

[0038] Experimental results are as follows Figure 6 As shown, Mn-NC-Meso can effectively activate persulfate, achieving an activation efficiency of 43.1% for PDS within 30 min of reaction. The Mn-NC-Meso / PDS system achieved 100% removal efficiency for all five novel pollutants. In comparison, Mn-NC-Macro's activation efficiency for PDS was 13.2%, and the removal efficiencies of the Mn-NC-Macro / PDS system for tetrabromobisphenol A (TBBPA), bisphenol A (BPA), chlorobenzene (4-CP), phenol (Phenol), and sulfamethoxazole (SMX) were 60.5%, 52.1%, 24.3%, 41.7%, and 55.7%, respectively. These results indicate that Mn-NC-Meso possesses excellent PDS activation performance, and the Mn-NC-Meso / PDS system has broad applicability for the degradation of novel pollutants.

[0039] Application Example 2: Referring to Application Example 1, the difference is that the pollutant is TBBPA, and the initial pH value of the reaction is adjusted to 3.0, 5.0, 7.0, 9.0, and 11.0, respectively.

[0040] Experimental results are as follows Figure 7 As shown, Mn-NC-Meso can activate persulfate to completely remove TBBPA within a pH range of 3.0 to 11.0, indicating that the catalytic system has a wide pH range of applicability.

[0041] Application Example 3: Referring to Application Example 1, the difference lies in that the pollutant is TBBPA, and common aquatic coexisting substances are present in the reaction system. The aquatic coexisting substance is 10 mM Cl... - 10 mM HCO3 - 10 mM H2PO4 - and 10 mg L -1 One of the humic acids (HA).

[0042] Experimental results are as follows Figure 7 As shown, the inhibitory effects of the three anions and HA on the degradation of TBBPA by the Mn-NC-Meso / PDS system were all less than 10%, indicating that the Mn-NC-Meso / PDS system has good resistance to interference from coexisting substances in water.

[0043] Application Example 4: Referring to Application Example 1, the difference lies in that the pollutant is TBBPA, and the reaction system contains active species quenchers. The active species quenchers are one of methanol (MeOH), tert-butanol (TBA), p-benzoquinone (p-BQ), furfuryl alcohol (FFA), and dimethyl sulfoxide (DMSO). MeOH can quench H₂O• and SO₄•. - TBA can quench HO•, and p-BQ can quench O2• - FFA can be extinguished. 1 O2 and DMSO can quench high-priced metal species.

[0044] Experimental results are as follows Figure 8 As shown, the inhibitory effects of MeOH, TBA, and DMSO on the degradation of TBBPA in the Mn-NC-Meso / PDS system were all less than 5%, while the degradation rates of TBBPA decreased from 100% to 84.6% and 48.8% respectively in the presence of p-BQ and FFA, indicating that O2• - and 1 O2 is an active species that causes TBBPA degradation.

[0045] Application Example 5: Referring to Application Example 1, the difference is that the pollutant is TBBPA. The used Mn-NC-Meso is successively centrifuged for recovery, washed with ethanol and dried overnight for use in the next cycle experiment. The degradation efficiency of TBBPA and metal leaching are examined during 5 cycles.

[0046] Experimental results are as follows Figure 9 As shown, after 5 cycles, the removal efficiency of Mn-NC-Meso for TBBPA remained above 90%; the leaching concentration of metallic manganese in each cycle was below 25 μg / L. -1 This indicates that Mn-NC-Meso exhibits good cycling stability and a low risk of metal loss.

[0047] Application Example 6: Solution A was prepared by mixing 15 g of polyacrylonitrile and 85 mL of dimethylformamide. Solution B was prepared by mixing 3 mL of acetone and 2 mL of dimethylformamide. Solution C was prepared by mixing 150 mg of Mn-NC-Meso, 3 mL of acetone, and 2 mL of dimethylformamide. Subsequently, solutions A, B, and C were mixed at a volume ratio of 4:1:1 and ultrasonically stirred for 6 h to obtain a casting solution. A mesoporous manganese single-atom catalytic membrane (Mn-NC-Meso@PAN) was obtained by electrospinning. The continuous flow reactor consisted of an influent system, a membrane reaction unit, and an effluent collection system. The influent system contained 0.1 mM sodium persulfate and 1.0 mg L... -1 The TBBPA mixed solution is pumped into the membrane reaction unit filled with Mn-NC-Meso@PAN, and the effluent solution of the effluent collection system is sampled, filtered and analyzed at preset time points.

[0048] Experimental results are as follows Figure 10 As shown, during the 24-hour operation of the continuous flow reactor, the TBBPA removal efficiency of the effluent from the Mn-NC-Meso@PAN membrane remained above 95%, indicating that the Mn-NC-Meso@PAN catalytic membrane has stable continuous catalytic degradation performance and good potential for practical application.

Claims

1. A method for preparing a mesoporous structure nitrogen-doped carbon supported manganese monatomic catalyst, characterized in that, The method includes the following steps: (1) Precursor complexation and loading: Manganese salt, 1,10-phenanthroline or its derivatives and magnesium hydroxide are dispersed in an organic solvent, and then subjected to ultrasonic treatment and heating and stirring at 60~80℃. The organic solvent is then removed by rotary evaporation to obtain the pyrolytic precursor. (2) Step-by-step calcination: after grinding and sieving the pyrolysis precursor obtained in step (1), it is placed in a tube furnace, first heated to 180-250℃ at a rate of 2-5 ℃ min -1 under an oxygen-containing atmosphere, then kept for 30-60 min, then switched to an inert protective atmosphere, heated to 600-650℃ at the same rate, then kept for 60-120 min for high-temperature carbonization treatment, and then taken out after natural cooling to room temperature to obtain a black carbonized product; (3) Template washing and purification: The black carbonized product obtained in step (2) is dispersed in an inorganic acid solution, stirred and washed at 60~80 °C, washed until neutral, dried and ground to obtain a black powdery mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst.

2. The production method according to claim 1, characterized by, In step (1), the manganese salt is selected from manganese acetate, manganese chloride or manganese nitrate; the 1,10-phenanthroline derivative is selected from 3,4,7,8-tetramethyl-1,10-phenanthroline or 2,9-dimethyl-1,10-phenanthroline; and the organic solvent is one or more of methanol, ethanol or acetonitrile.

3. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of manganese salt, 1,10-phenanthroline or its derivatives to magnesium hydroxide is 0.50 ~ 3.00: 9.00: 600, and the concentration of manganese salt is 0.0015-0.03 mol / L.

4. The method of claim 1, wherein, The ultrasonic frequency in step (1) is 10~50kHz, the ultrasonic time is 10~60 min, and the heating and stirring time is 6~12 h.

5. The preparation method according to claim 1, characterized in that, The inorganic strong acid used in the acid washing in step (3) is one or more of hydrochloric acid, sulfuric acid or nitric acid, the concentration is 0.5-1.0 M, the solid-liquid ratio of acid washing is 5-10 g / L -1 , and the acid washing time is 4-8 h.

6. The mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst prepared by the method of claim 1.

7. The use of the mesoporous structure nitrogen-doped carbon supported manganese monatomic catalyst prepared by the method of claim 1 in the degradation of new pollutants in wastewater in a persulfate-based advanced oxidation system, characterized in that, The catalyst and persulfate are added to the sewage to be treated, the catalyst addition amount is 0.02-0.20 g / L -1 , the persulfate concentration is 0.1-2.0 mM, and the sewage pH value range is 3.0-11.0; Or, the catalytic membrane prepared by mesoporous structure nitrogen-doped carbon supported manganese monatomic catalyst is placed in a continuous flow reaction device for treating water bodies containing new pollutants; the concentration of the new pollutants in the inlet water is 1 mg L -1 , and the concentration of persulfate is 0.1 mM.

8. Use according to claim 7, characterized in that, The new pollutants include at least one of tetrabromobisphenol A, bisphenol A, phenol, sulfamethoxazole, and chlorobenzene; the persulfate is a permonosulfate or a perdisulfate.

9. Use according to claim 7, characterized in that, The catalyst membrane is prepared as follows: the obtained mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst is mixed with polyacrylonitrile and the catalyst membrane is prepared by electrospinning.

10. Use according to claim 9, characterized in that, The specific method for preparing the catalytic membrane is as follows: a mesoporous nitrogen-doped carbon-supported manganese single-atom catalyst is dispersed in a dimethylformamide solution containing polyacrylonitrile, and acetone is added to adjust the volatilization rate. The mixture is then stirred to form a homogeneous casting solution. The casting solution was then transferred to an electrospinning device and sprayed into filaments under a high-voltage electric field. The filaments were then solidified on a receiving roller and dried to obtain a self-supporting catalytic membrane. The casting solution preparation process was as follows: 10-20 g of polyacrylonitrile was dissolved in 50-100 mL of dimethylformamide to obtain solution A; 5-10 mL of DMF and 5-10 mL of acetone were mixed to obtain solution B; 150-300 mg of catalyst, 5-10 mL of DMF and 5-10 mL of acetone were mixed to obtain solution C; solutions A, B and C were mixed at a volume ratio of 4:1:1 and stirred for 6-12 h to form the casting solution.

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