Ozone catalyst, preparation method and application thereof

Abstract

This invention relates to the field of wastewater treatment technology, specifically to an ozone catalyst, its preparation method, and its application. The ozone catalyst uses a composite material of boron-doped activated carbon and nitrogen-doped carbon dots as a matrix, and is loaded with manganese, cerium, and copper. The nitrogen-doped carbon dots effectively anchor metal ions, forming uniformly dispersed metal-nitrogen-doped carbon dot active sites, which not only prevents the aggregation of metal oxide nanoparticles but also maximizes the exposure of active sites. Simultaneously, combined with the stabilizing effect of CeO2, the metal active components are firmly anchored, reducing the metal dissolution rate. Furthermore, the hydrophobic-hydrophilic balance on the surface of the ozone catalyst support and the chemical inertness of the carbon material effectively reduce the irreversible adsorption of natural organic matter and anions in the water at the active sites, preventing catalyst deactivation and improving the catalyst's resistance to poisoning.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an ozone catalyst, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Industrial wastewater is complex in composition, and its quality and quantity are varied and complex, making it difficult and costly to treat. In particular, industrial wastewater containing phenols, polycyclic aromatic hydrocarbons, and heterocyclic compounds is difficult to degrade, is highly toxic, and easily accumulates in organisms, seriously endangering human health and ecological safety, and has always been a problem in the water treatment industry.

[0004] Traditional water treatment processes combining physical, chemical, and biological methods are insufficient for effectively improving quality and efficiency; comprehensive prevention and control measures are necessary to ensure wastewater meets discharge standards. Advanced oxidation technology, however, is a highly efficient wastewater treatment technology that generates strongly oxidizing hydroxyl radicals to decompose organic matter in water, thereby mineralizing it into CO2 and H2O. Ozone catalysts can be divided into two categories: homogeneous catalytic reactions using metal ions as catalysts and heterogeneous catalytic reactions using solid catalysts. Homogeneous catalytic ozone oxidation technology suffers from several problems, including low mineralization rates, secondary pollution from the introduction of metal ions, and low oxidant utilization efficiency. It requires subsequent treatment after the ozone catalytic oxidation reaction, which complicates the process, increases water treatment costs, and limits its practical application. Furthermore, the most researched heterogeneous catalysts in ozone catalytic oxidation technology include metal oxides and metal oxides supported on supports, precious metals supported on supports, and porous materials such as activated carbon. These catalysts exist in solid form and have advantages such as high reactivity, fast reaction rates, easy separation, and simple processes. However, these catalytic reactions suffer from the problem of some metal ions dissolving out, resulting in reduced catalyst activity and further environmental pollution.

[0005] In addition, some components in the wastewater may be irreversibly adsorbed onto the active sites of the catalyst or react with the active components, causing the catalyst to lose its activity. Summary of the Invention

[0006] To overcome the above problems, the present invention provides an ozone catalyst, its preparation method and application.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an ozone catalyst having a matrix of a composite material consisting of boron-doped activated carbon and nitrogen-doped carbon dots, and loaded with manganese, cerium and copper.

[0008] In one or more embodiments, the total loading of manganese, cerium and copper is 10 to 20 wt%.

[0009] In one or more embodiments, the molar ratio of manganese, cerium and copper is (3~5):(1~2):(0.5~1.5).

[0010] A second aspect of the present invention provides a method for preparing the ozone catalyst described in the first aspect, comprising the following steps: (1) The boron precursor was dissolved in ethanol to obtain a boron precursor solution; the activated carbon was impregnated in the boron precursor solution by equal volume impregnation, ultrasonicated and then oscillated, and after drying, the boron-doped activated carbon was obtained by first heat treatment. (2) Dissolve the carbon source and nitrogen source in water, perform a second heat treatment, collect the liquid by centrifugation, and obtain a solution of nitrogen-doped carbon dots by dialysis; (3) Disperse boron-doped activated carbon in a solution containing nitrogen-doped carbon dots, and obtain a composite material of boron-doped activated carbon and nitrogen-doped carbon dots after a third heat treatment. (4) Using an equal-volume impregnation method, the composite material of boron-doped activated carbon and nitrogen-doped carbon dots is impregnated in a mixed solution of manganese salt, cerium salt and copper salt. After impregnation, it is sealed and aged, dried and then subjected to a fourth heat treatment in an oxygen atmosphere to obtain an ozone catalyst.

[0011] In one or more embodiments, in step (1), the boron precursor includes one or more of boric acid, boron oxide (B2O3), and trimethyl borate.

[0012] In one or more embodiments, in step (1), the concentration of the boron precursor is 10~30 g / L, preferably 20 g / L.

[0013] In one or more embodiments, in step (1), the activated carbon is coconut shell activated carbon or coal-based activated carbon, with a particle size of 20-40 mesh and a specific surface area ≥ 1000 m². 2 / g.

[0014] In one or more embodiments, in step (1), the boron-to-carbon ratio is (0.01~0.05):1.

[0015] In one or more embodiments, in step (1), the activated carbon needs to be pretreated before the reaction. The pretreatment method includes ultrasonic cleaning with nitric acid, deionized water and anhydrous ethanol in sequence.

[0016] Preferably, the ultrasonic cleaning time is 20-40 minutes, and more preferably 30 minutes.

[0017] Preferably, the concentration of nitric acid is 0.08~0.12 mol / L, and more preferably 0.1 mol / L.

[0018] In one or more embodiments, in step (1), the ultrasound time is 0.5 to 2 hours, preferably 1 hour.

[0019] In one or more embodiments, in step (1), the temperature of the oscillation impregnation is 50~80 ℃, preferably 60 ℃; the rotation speed of the oscillation impregnation is 100~150 rpm; and the oscillation impregnation time is 6~12 h.

[0020] In one or more embodiments, in step (1), the first heat treatment is carried out in an inert gas atmosphere; the temperature of the first heat treatment is 700~900 ℃; and the time of the first heat treatment is 2~3 h.

[0021] In one or more embodiments, in step (2), the carbon source includes one or more of citric acid, salicylic acid and tartaric acid.

[0022] In one or more embodiments, in step (2), the nitrogen source includes one or more of urea, ammonium carbonate and ethylenediamine.

[0023] In one or more embodiments, in step (2), the carbon-nitrogen molar ratio (C / N) of the carbon source and nitrogen source is 1:(2~10).

[0024] In one or more embodiments, in step (2), the temperature of the second heat treatment is 160~200 ℃; the time of the second heat treatment is 4~6 h.

[0025] In one or more embodiments, in step (2), after the second heat treatment, the pH of the reaction product solution is adjusted to 7.0 using a saturated NaOH solution.

[0026] In one or more embodiments, in step (2), the molecular weight cutoff for dialysis is 500~1500 Da, preferably 500~1000 Da; the dialysis time is 24~48 h.

[0027] In one or more embodiments, in step (3), the mass ratio of boron-doped activated carbon to nitrogen-doped carbon dots is (20~30):1, preferably 25:1.

[0028] In one or more embodiments, in step (3), the temperature of the third heat treatment is 150~180 ℃; the time of the second heat treatment is 4~8 h.

[0029] In one or more embodiments, in step (4), the manganese salt includes one or more of manganese nitrate (Mn(NO3)2) and manganese acetate (Mn(CH3COO)2).

[0030] In one or more embodiments, in step (4), the cerium salt includes one or more of cerium nitrate (Ce(NO3)3) and cerium ammonium nitrate ((NH4)2Ce(NO3)6).

[0031] In one or more embodiments, in step (4), the copper salt includes one or more of copper nitrate (Cu(NO3)2) and copper acetate (Cu(CH3COO)2).

[0032] In one or more embodiments, in step (4), the molar ratio of manganese salt, cerium salt and copper salt is (3~5):(1~2):(0.5~1.5).

[0033] In one or more embodiments, in step (4), ultrasonic treatment is used during impregnation, and the ultrasonic treatment time is 30 to 60 minutes.

[0034] In one or more embodiments, in step (4), the sealing and aging time is 6 to 12 hours.

[0035] In one or more embodiments, in step (4), the oxygenated atmosphere is air.

[0036] In one or more embodiments, in step (4), the temperature of the third heat treatment is 500~600 ℃; the time of the second heat treatment is 2~4 h.

[0037] A third aspect of the present invention provides an ozone catalyst as described in the first aspect or a catalyst prepared by the preparation method as described in the second aspect for the degradation of organic pollutants in wastewater.

[0038] In one or more embodiments, the dosage of ozone catalyst is 100~150 g / L.

[0039] The beneficial effects of this invention are as follows: In the ozone catalyst provided by this invention, nitrogen-doped carbon dots can effectively anchor metal ions, forming uniformly dispersed active sites of metal-nitrogen-doped carbon dots. This not only prevents the aggregation of metal oxide nanoparticles but also maximizes the exposure of active sites. Simultaneously, combined with the stabilizing effect of CeO2, the metal active components are firmly anchored, reducing the metal dissolution rate. Furthermore, the hydrophobic-hydrophilic balance on the surface of the ozone catalyst support and the chemical inertness of the carbon material effectively reduce the irreversible adsorption of natural organic matter and anions in the water at the active sites, preventing catalyst deactivation and improving the catalyst's resistance to poisoning. Detailed Implementation

[0040] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] Currently, the most studied heterogeneous catalysts in ozone catalytic oxidation technology include metal oxides and metal oxides supported on supports, noble metals supported on supports, and porous materials such as activated carbon. These catalysts exist in solid form and have advantages such as high reaction activity, fast reaction rate, easy separation, and simple process. However, the reaction of these catalysts suffers from the problem of partial metal ion dissolution, which leads to reduced catalyst activity and further environmental pollution.

[0043] In addition, some components in the wastewater may be irreversibly adsorbed onto the active sites of the catalyst or react with the active components, causing the catalyst to lose its activity.

[0044] In the ozone catalyst provided by this invention, nitrogen-doped carbon dots can effectively anchor metal ions, forming uniformly dispersed active sites of metal-nitrogen-doped carbon dots. This not only prevents the aggregation of metal oxide nanoparticles but also maximizes the exposure of active sites. Simultaneously, combined with the stabilizing effect of CeO2, the metal active components are firmly anchored, reducing the metal dissolution rate. Furthermore, the hydrophobic-hydrophilic balance on the surface of the ozone catalyst support and the chemical inertness of the carbon material effectively reduce the irreversible adsorption of natural organic matter and anions in the water at the active sites, preventing catalyst deactivation and improving the catalyst's resistance to poisoning.

[0045] In the ozone catalyst provided by this invention, the electron-deficient surface of boron-doped activated carbon enhances the adsorption of ozone, and nitrogen-doped carbon dots (N-CDs) can rapidly "extract" electrons from the metal to generate O3· - (Ozone anion radicals), which are rapidly converted into hydroxyl radicals (·OH); while the reduction of metal ions is usually the rate-controlling step of the reaction, nitrogen-doped carbon dots (N-CDs) can preferentially adsorb and activate water molecules or pollutant molecules, extract electrons from them, and then transfer these electrons to high-valence metal ions, accelerating the redox of metal ions and significantly accelerating the generation of hydroxyl radicals (·OH), showing excellent degradation and mineralization capabilities for recalcitrant organic matter.

[0046] The ozone catalyst provided by this invention achieves highly efficient synergy between photocatalysis and ozone catalysis: nitrogen-doped carbon dots (N-CDs) act as a key bridge, deeply integrating the two advanced oxidation processes. Under illumination, nitrogen-doped carbon dots (N-CDs) are excited to generate photogenerated electrons (e-electrons). - These electrons are rapidly transferred to the adsorbed ozone (O3) molecules, greatly accelerating the rate at which ozone decomposes to generate hydroxyl radicals (·OH); simultaneously, photogenerated holes (h + It can directly oxidize pollutants or water molecules, producing more active species. This significantly improves energy utilization efficiency and pollutant degradation rate.

[0047] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0048] Example 1 Preparation of ozone catalysts: (1) Coconut shell activated carbon (20-40 mesh, specific surface area of ​​1200 m²) 2 The sample (g) was ultrasonically cleaned sequentially with 0.1 mol / L nitric acid, deionized water, and anhydrous ethanol for 30 min, and then dried in an electric heating oven at 105 ℃ until constant weight.

[0049] 1 g of boric acid was dissolved in 50 mL of ethanol, followed by the addition of 10 g of pretreated coconut shell activated carbon. The mixture was sonicated for 1 h and then transferred to a constant temperature water bath shaker. It was shaken and impregnated at 60 ℃ and 120 rpm for 12 h. Subsequently, it was dried in an electric heating oven at 105 ℃ until constant weight. The dried sample was placed in a tube furnace and heated to 800 ℃ at a heating rate of 5 ℃ / min under a nitrogen atmosphere. This temperature was maintained for 2 h. After cooling to room temperature, it was washed with deionized water until neutral and then dried in a drying oven at 105 ℃ until constant weight to obtain boron-doped activated carbon (denoted as B-AC).

[0050] (2) Dissolve 2.1g of citric acid and 3.6g of urea (C / N=1:6) in 60 mL of water to form a clear and transparent solution. Transfer the entire solution to a polytetrafluoroethylene liner and seal it in a stainless steel hydrothermal reactor. Place the reactor in a forced-air drying oven and heat it from room temperature to 180℃ at a rate of 5℃ / min. Maintain the temperature at this temperature for 4 h. After cooling, adjust the pH of the reaction product solution to 7 with saturated NaOH solution. Centrifuge the reaction solution at 10000 rpm for 20 min and collect the supernatant. Repeat the centrifugation and collection three times. Then dialyze the solution using a dialysis bag with a molecular weight cutoff of 1000 Da for 24 h, changing the water every 6 h to remove impurity ions and obtain a solution of nitrogen-doped carbon dots (denoted as N-CDs).

[0051] (3) Disperse 5g of B-AC in a solution containing 200mg of N-CDs, sonicate for 30 min, transfer the well-mixed suspension to a polytetrafluoroethylene liner, and seal it in a stainless steel hydrothermal reactor; place the reactor in a forced-air drying oven, raise the temperature from room temperature to 160℃ at a rate of 5℃ / min, and keep the temperature constant for 6 h. After the reaction, allow the reactor to cool naturally to room temperature, and collect the product by centrifugation or filtration; wash with deionized water and anhydrous ethanol alternately 3-5 times; dry the washed solid product in a vacuum oven at 70℃ to obtain a composite material of boron-doped activated carbon and nitrogen-doped carbon dots (denoted as N-CDs / B-AC). (4) Manganese nitrate (Mn(NO3)2), cerium nitrate (Ce(NO3)3), and copper nitrate (Cu(NO3)2) were dispersed in deionized water at a molar ratio of Mn:Ce:Cu = 4:1:1, with a total loading of 15% for manganese, cerium, and copper. N-CDs / B-AC were added to the solution in batches and slowly. The mixture was ultrasonically treated for 30 min. After impregnation, the sample was immediately sealed in a container and aged at room temperature for 12 h. After aging, the sample was transferred to a forced-air drying oven and dried at 100 ℃ for 10 h. The dried sample was placed in a muffle furnace and heated to a set temperature of 600 ℃ at a heating rate of 3 ℃ / min under an air atmosphere. The sample was then calcined at this temperature for 3 h. After natural cooling to room temperature, the ozone catalyst (denoted as NB-MCU) was obtained.

[0052] Comparative Example 1 Compared to Example 1, the matrix is ​​only boron-doped activated carbon.

[0053] (1) Dissolve 1 g of boric acid in 50 mL of ethanol, then add 10 g of pretreated coconut shell activated carbon, sonicate for 1 h, transfer to a constant temperature water bath shaker, and shake and soak for 12 h at 60 ℃ and 120 rpm; then place in an electric heating drying oven at 105 ℃ to dry to constant weight; place the dried sample in a tube furnace, heat to 800 ℃ at a heating rate of 5 ℃ / min under a nitrogen atmosphere, and maintain this temperature for calcination for 2 h. After cooling to room temperature, wash with deionized water until neutral, place in a drying oven and dry at 105 ℃ to constant weight to obtain boron-doped activated carbon (denoted as B-AC).

[0054] (4) Manganese nitrate (Mn(NO3)2), cerium nitrate (Ce(NO3)3), and copper nitrate (Cu(NO3)2) were dispersed in deionized water at a molar ratio of Mn:Ce:Cu = 4:1:1, with a total loading of 15% for manganese, cerium, and copper. B-AC was added to the solution in batches and slowly, and the mixture was sonicated for 30 min. After impregnation, the sample was immediately sealed in a container and aged at room temperature for 12 h. After aging, the sample was transferred to a forced-air drying oven and dried at 100 ℃ for 10 h. The dried sample was placed in a muffle furnace and heated to a set temperature of 600 ℃ at a heating rate of 3 ℃ / min under an air atmosphere, and calcined at this temperature for 3 h. After natural cooling to room temperature, the ozone catalyst (denoted as B-MCU-1) was obtained.

[0055] Example 2 Using benzene and phenol as target pollutants, experimental water with a COD of 3000 mg / L and a pH of 7 was prepared. The reactor volume was 1.5 L, the catalyst dosage was 375 g, and the reaction time was 90 min. The ozone generator produced ozone at a rate of 5 g / h, resulting in an ozone concentration of 2.5 mg / L.

[0056] Under natural light, when the catalyst was the ozone catalyst prepared in Example 1, the COD removal efficiency reached 96.05% after the reaction. However, under light-protected conditions, when the catalyst was the ozone catalyst prepared in Example 1, the COD removal efficiency was 81.7% after the reaction.

[0057] A comparison of conditions with and without light shows that the catalytic mineralization efficiency of the ozone catalyst is higher under natural light than under light-shielded conditions. This is because the ozone catalyst provided by this invention can achieve highly efficient synergy between photocatalysis and ozone catalysis: nitrogen-doped carbon dots (N-CDs) act as a key bridge, deeply integrating the two advanced oxidation processes. Under light, nitrogen-doped carbon dots (N-CDs) are excited to generate photogenerated electrons (e-electrons). -These electrons are rapidly transferred to the adsorbed ozone (O3) molecules, greatly accelerating the rate at which ozone decomposes to generate hydroxyl radicals (·OH); simultaneously, photogenerated holes (h + It can directly oxidize pollutants or water molecules, producing more active species. This significantly improves energy utilization efficiency and pollutant degradation rate.

[0058] Under natural light, when the catalyst was the one prepared in Comparative Example 1, the COD removal efficiency was 75.45% after the reaction. Comparing the catalytic mineralization results of the catalysts in Example 1 and Comparative Example 1, it can be seen that the catalytic mineralization efficiency decreases when nitrogen-doped carbon dots are lacking. This is because nitrogen-doped carbon dots (N-CDs) can rapidly "extract" electrons from the metal to generate O3· - (Ozone anion radicals), which are rapidly converted into hydroxyl radicals (·OH); while the reduction of metal ions is usually the rate-controlling step of the reaction, nitrogen-doped carbon dots (N-CDs) can preferentially adsorb and activate water molecules or pollutant molecules, extract electrons from them, and then transfer these electrons to high-valence metal ions, accelerating the redox of metal ions and significantly accelerating the generation of hydroxyl radicals (·OH), showing excellent degradation and mineralization capabilities for recalcitrant organic matter.

[0059] After the catalytic oxidation reaction was completed, the mixture in the reactor was filtered through a 0.45 μm aqueous microporous membrane to completely separate the solid catalyst. An appropriate amount of filtrate was taken, acidified with concentrated nitric acid to pH < 2, and stored at 4 ℃ for later analysis. The content of manganese (Mn), cerium (Ce), and copper (Cu) in the filtrate was quantitatively analyzed using inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7800).

[0060] For the ozone catalyst (NB-MCU) prepared in Example 1: Under the reaction conditions of Example 2 (light irradiation, treatment of benzene / phenol wastewater for 90 min), the concentration of metal ions in the water sample after the reaction was measured. Calculations showed that (dissolution rate = ((total mass of metal ions in the water sample after reaction / theoretical mass of the metal in the total mass of catalyst added) × 100%) resulted in dissolution rates of 0.8%, 0.1%, and 0.5% for manganese (Mn), cerium (Ce), and copper (Cu), respectively. This result demonstrates that the active metal components in the catalyst are firmly anchored on the composite support by the synergistic effect of nitrogen-doped carbon dots (N-CDs) and CeO2, remaining stable even in a strongly oxidizing reaction environment, effectively avoiding secondary pollution.

[0061] For the catalyst prepared in Comparative Example 1 (B-MCU-1): under the same reaction conditions, the dissolution rates of manganese (Mn), cerium (Ce), and copper (Cu) were 2.5%, 0.3%, and 1.8%, respectively, which were significantly higher than those of the catalyst of the present invention.

[0062] Example 3 Using dimethyl sulfoxide and N-methylpyrrolidone as target pollutants, experimental water with a COD of 2000 mg / L and a pH of 7 was prepared. The reactor volume was 1.5 L, the catalyst dosage was 250 mg, and the reaction time was 90 min. The ozone generator produced ozone at a rate of 5 g / h, resulting in an ozone concentration of 2.5 mg / L.

[0063] Under natural light, when the catalyst was the ozone catalyst prepared in Example 1, the COD removal efficiency reached 93.5% after the reaction. However, under light-protected conditions, when the catalyst was the ozone catalyst prepared in Example 1, the COD removal efficiency was 76.4% after the reaction.

[0064] Under natural light, when the catalyst is the one prepared in Comparative Example 1, the COD removal efficiency is 65.34% after the reaction.

[0065] Example 4 Cyclic experiments were conducted to test the lifespan of the NB-MCU catalyst.

[0066] Using benzene and phenol as target pollutants, experimental water with a COD of 3000 mg / L and a pH of 7 was prepared. The reactor volume was 1.5 L, the catalyst dosage was 375 mg, and the reaction time was 90 min. The ozone generator produced ozone at a rate of 5 g / h, resulting in an ozone concentration of 2.5 mg / L. Ten consecutive experiments were conducted, and the results are shown in Table 1. Based on the results of the cyclic experiments, it can be further concluded that the NB-MCU-1 catalyst exhibits stable catalytic performance and a long service life.

[0067] Table 1 Results of Cyclic Experiments

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ozone catalyst, characterized in that, It uses a composite material made of boron-doped activated carbon and nitrogen-doped carbon dots as the matrix, and is loaded with manganese, cerium and copper.

2. The ozone catalyst as described in claim 1, characterized in that, The total loading of manganese, cerium and copper is 10-20 wt%; Alternatively, the molar ratio of manganese, cerium, and copper is (3~5):(1~2):(0.5~1.5).

3. The method for preparing the ozone catalyst according to claim 1 or 2, characterized in that, Includes the following steps: (1) The boron precursor was dissolved in ethanol to obtain a boron precursor solution; the activated carbon was impregnated in the boron precursor solution by equal volume impregnation, ultrasonicated and then oscillated, and after drying, the boron-doped activated carbon was obtained by first heat treatment. (2) Dissolve the carbon source and nitrogen source in water, perform a second heat treatment, collect the liquid by centrifugation, and obtain a solution of nitrogen-doped carbon dots by dialysis; (3) The boron-doped activated carbon is dispersed in a solution containing nitrogen-doped carbon dots, and a composite material of boron-doped activated carbon and nitrogen-doped carbon dots is obtained after a third heat treatment. (4) Using an equal-volume impregnation method, the composite material of boron-doped activated carbon and nitrogen-doped carbon dots is impregnated in a mixed solution of manganese salt, cerium salt and copper salt. After impregnation, it is sealed and aged, dried and then subjected to a fourth heat treatment in an oxygen atmosphere to obtain an ozone catalyst.

4. The preparation method according to claim 3, characterized in that, In step (1), the boron precursor includes one or more of boric acid, boron oxide (B2O3), and trimethyl borate; Alternatively, in step (1), the concentration of the boron precursor is 10~30 g / L, preferably 20 g / L; Alternatively, in step (1), the activated carbon is coconut shell activated carbon or coal-based activated carbon, with a particle size of 20-40 mesh and a specific surface area ≥1000 m². 2 / g; Alternatively, in step (1), the boron-to-carbon ratio is (0.01~0.05):

1.

5. The preparation method according to claim 3, characterized in that, In step (1), the ultrasound time is 0.5~2 h, preferably 1 h; Alternatively, in step (1), the temperature of the oscillation impregnation is 50~80 ℃, preferably 60 ℃; the rotation speed of the oscillation impregnation is 100~150 rpm; and the oscillation impregnation time is 6~12 h. Alternatively, in step (1), the first heat treatment is carried out in an inert gas atmosphere; the temperature of the first heat treatment is 700~900 ℃; and the time of the first heat treatment is 2~3 h.

6. The preparation method according to claim 3, characterized in that, In step (2), the carbon source includes one or more of citric acid, salicylic acid and tartaric acid; Alternatively, in step (2), the nitrogen source includes one or more of urea, ammonium carbonate, and ethylenediamine; Alternatively, in step (2), the carbon-nitrogen molar ratio (C / N) of the carbon source and nitrogen source is 1:(2~10). Alternatively, in step (2), the temperature of the second heat treatment is 160~200 ℃; the time of the second heat treatment is 4~6 h; Alternatively, in step (2), after the second heat treatment, the pH of the reaction product solution is adjusted to 7.0 using a saturated NaOH solution; Alternatively, in step (2), the molecular weight cutoff for dialysis is 500~1500 Da, preferably 500~1000 Da; the dialysis time is 24~48 h.

7. The preparation method according to claim 3, characterized in that, In step (3), the mass ratio of boron-doped activated carbon to nitrogen-doped carbon dots is (20~30):1, preferably 25:1; Alternatively, in step (3), the temperature of the third heat treatment is 150~180 ℃; the time of the second heat treatment is 4~8 h.

8. The preparation method according to claim 3, characterized in that, In step (4), the manganese salt includes one or more of manganese nitrate (Mn(NO3)2) and manganese acetate (Mn(CH3COO)2); Alternatively, in step (4), the cerium salt includes one or more of cerium nitrate (Ce(NO3)3) and cerium ammonium nitrate ((NH4)2Ce(NO3)6); Alternatively, in step (4), the copper salt includes one or more of copper nitrate (Cu(NO3)2) and copper acetate (Cu(CH3COO)2); Alternatively, in step (4), the molar ratio of manganese salt, cerium salt, and copper salt is (3~5):(1~2):(0.5~1.5). Alternatively, in step (4), ultrasonic treatment is used during impregnation, and the ultrasonic treatment time is 30~60 min; Alternatively, in step (4), the sealing and aging time is 6~12 h; Alternatively, in step (4), the oxygen-rich atmosphere is air; Alternatively, in step (4), the temperature of the third heat treatment is 500~600 ℃; the time of the second heat treatment is 2~4 h.

9. The ozone catalyst according to claim 1 or 2, or the catalyst prepared by the preparation method according to any one of claims 3 to 8, is used for the degradation of organic pollutants in wastewater.

10. The application as described in claim 9, characterized in that, The dosage of ozone catalyst is 100~150 g / L.

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