Method for purifying water by catalyzing ozonation through nitrogen-fluorine co-doped carbon-loaded cobalt nanomaterial

Abstract

The invention discloses a method for purifying water by catalyzing ozonation through a nitrogen-fluorine co-doped carbon-loaded cobalt nanomaterial. Co-ZIF-8 and polytetrafluoroethylene (PTFE) are respectively used as a precursor and a fluorine source, and the nitrogen-fluorine co-doped carbon-loaded cobalt nano-catalyst is successfully prepared through an etching synchronous doping strategy. The composite material can be used for catalyzing ozone to degrade organic pollutants in water. Nitrogen doping can promote formation of a metal-nitrogen coordination structure, and decomposition of ozone on the surface of the catalyst is facilitated. Fluorine modification can significantly enhance the hydrophilicity of the composite material and accelerate the solid-liquid reaction of ozone in a solution and a catalyst interface, and the strong electron withdrawing effect of fluorine can effectively adjust the electronic structure of the catalyst and promote the generation of strong oxidizing active oxygen species, thereby achieving efficient and rapid removal of pollutants. The water treatment method solves the problem of low ozone utilization rate in a conventional catalytic ozonation process, has the advantages of high reaction rate and stable treatment effect, and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the fields of materials and wastewater treatment technology, specifically, a novel method for water purification using nitrogen-fluorine co-doped carbon-supported cobalt nanomaterials catalyzing ozone oxidation. Background Technology

[0002] With the increasing demand for clean water and a safe ecological environment, the development of efficient and environmentally friendly wastewater treatment technologies is urgently needed. Conventional water purification technologies such as physical, biological, and incineration methods have low treatment efficiency and are unable to effectively remove recalcitrant organic pollutants from water bodies. Advanced oxidation processes (AOPs) based on the green oxidant ozone (O3, 2.08 V vs SHE) are widely used to remove organic pollutants from water bodies to ensure water supply safety. However, the limited solubility and stability of O3 in water result in low ozone utilization rates, severely restricting the application of ozone oxidation processes. In addition, the selectivity of ozone oxidation leads to slow oxidation rates and low mineralization rates for some recalcitrant organic pollutants such as carboxylic acids and aldehydes, making complete removal impossible.

[0003] Catalytic ozonation, especially heterogeneous catalytic ozonation (HCO3), is a very promising technology that relies on the activation of O3 on the catalyst surface to generate highly oxidizing reactive oxygen species (ROS), such as hydroxyl radicals. · OH, 2.70 V), singlet oxygen ( 1 O2, 1.88 V), surface atomic oxygen ( * O ad Ozone catalysts, such as those with a volatilization efficiency of 2.43 V, can rapidly and effectively remove stubborn organic pollutants from wastewater. Common heterogeneous ozone catalysts include metal oxides (such as MnO2, Fe2O3, CuO, CeO2, MnFe2O4, etc.), carbon materials (activated carbon, graphene, carbon nanotubes, etc.), and supported metal materials. Among these, metal-based catalysts pose a risk of secondary pollution due to leaching issues. The activity and stability of carbon materials are often inferior to those of metal-based catalysts. To improve the efficiency and tunability of catalytic ozonation reactions, researchers are dedicated to designing new catalysts to stimulate ozone production and generate more active oxygen to oxidize organic pollutants in wastewater. Metal-organic frameworks (MOFs) are a new type of carbon material composed of metal ions or clusters bridged by organic functional groups, and have been proven to be ideal precursors for the pyrolysis preparation of carbon-supported gold composite catalysts. Specifically, the highly tunable metal sites and organic ligands facilitate the full exposure of metal sites, while the well-developed pore structure ensures mass transfer. Currently, MOF-derived carbon materials have been extensively studied in wastewater treatment and AOPs degradation of persistent organic pollutants. However, due to their slow kinetics, they suffer from low ozone utilization efficiency and unsatisfactory pollutant removal effects. Further adjustments to MOF-derived carbon materials are needed to develop more robust and efficient catalysts. SUMMARY

[0004] In view of the problems of low ozone utilization efficiency and unsatisfactory pollutant removal effect of the existing heterogeneous catalytic ozonation water treatment technology, the application provides a novel water quality purification method of nitrogen and fluorine co-doped carbon loaded cobalt nanomaterial catalytic ozonation.

[0005] The application is realized by the following technical scheme:

[0006] 1. A nitrogen and fluorine co-doped carbon loaded cobalt nanomaterial catalytic ozonation water quality purification method, characterized by comprising the following steps in the preparation method of the nitrogen and fluorine co-doped carbon loaded cobalt nanomaterial: (1) dissolving zinc salt and cobalt salt in a methanol solution to obtain solution A, dissolving 2-methyl imidazole in a methanol solution to obtain solution B, pouring solution A into solution B to obtain a mixed solution, then stirring vigorously, standing, centrifuging and washing with methanol, and drying to obtain a precipitate; (2) ultrasonic dispersion of the precipitate in an ethanol solution, addition of polytetrafluoroethylene dispersion liquid as a fluorine source, sufficient stirring and mixing of the obtained mixture, and evaporation treatment to obtain a precursor; (3) placing the precursor obtained in (2) in a tube furnace, performing heat treatment under an inert atmosphere, and naturally cooling to room temperature to obtain the cobalt, nitrogen and fluorine co-doped nanocarbon material.

[0007] 2. According to the above preparation method, characterized in that in step (1), the cobalt salt is any one of cobalt acetylacetone, cobalt nitrate and cobalt acetate.

[0008] 3. According to the above preparation method, characterized in that in step (1), the concentration of 2-methyl imidazole is 0.4-4 mol / L; the concentration of the zinc salt is 0.01-0.5 mol / L; and the concentration of the cobalt salt is 0.001-0.5 mol / L.

[0009] 4. According to the above preparation method, characterized in that in step (2), the mass fraction of the polytetrafluoroethylene dispersion liquid is 60%; and the mass ratio of the precipitate to polytetrafluoroethylene is 1:0.63-1:50.4.

[0010] 5. According to the above preparation method, characterized in that in step (3), the inert atmosphere is Ar or N2, and the flow rate is 50-200 mL / min; the heat treatment is as follows: heating to 800-1000℃ at a heating rate of 5℃ / min and keeping for 3 h, and then naturally cooling to room temperature.

[0011] 6. The application also provides a water purification method by catalytic ozonation of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial prepared by the above preparation method. Specifically, 0.01-5 g / L of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial is added to a solution containing organic pollutants, fully stirred, and then connected to an ozone generator. The mixed gas of oxygen and ozone is introduced into the wastewater through the aeration head at a flow rate of 10-1000 mL / min, wherein the concentration of ozone is 5-100 mg / L, and the reaction is started under stirring at room temperature.

[0012] The technical principle of the application is:

[0013] The nitrogen and fluorine co-doped carbon supported cobalt nanocatalyst is prepared by etching and synchronous doping strategy with Co-ZIF-8 and polytetrafluoroethylene as precursors and fluorine sources, respectively. Nitrogen doping can promote the formation of metal-nitrogen coordination structure, which is beneficial to the decomposition of ozone on the surface of the catalyst. Fluorine modification can significantly enhance the hydrophilicity of the composite material, accelerate the solid-liquid reaction at the interface of ozone and the catalyst in the solution, and at the same time, its strong electron-withdrawing effect can effectively adjust the electronic structure of the catalyst, promote the generation of strong oxidizing active oxygen species, and ultimately realize efficient and rapid removal of pollutants.

[0014] The main advantages of the application are:

[0015] (1) A nitrogen and fluorine co-doped carbon supported cobalt nanomaterial is provided and used in the process of catalytic ozonation degradation of organic pollutants. The design of the surface hydrophilic microenvironment and the coordination of the metal center on the surface of the material make it have high catalytic ozonation activity.

[0016] (2) The nitrogen and fluorine co-doped carbon supported cobalt nanomaterial exhibits high catalytic ozonation performance. Taking the oxidation degradation of oxalic acid (OA) as an example, the Co@FNC / O3 system achieves 96.1% removal of oxalic acid in 30 min, and the corresponding pseudo-first-order kinetic constant is 0.113 min -1 , which is 56.5 times, 2.6 times, 3.9 times and 2.7 times, respectively, of the O3 (1%, 0.002 min -1 ), NC / O3 (23%, 0.043 min -1 ), CoNC / O3 (61%, 0.029 min -1 ) and FNC / O3 (72%, 0.042 min -1 ) systems.

[0017] (3) The catalytic ozonation system (Co@FNC / O3) with the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial as catalyst has high ozone mass transfer performance, and the ozone utilization rate for removing actual coal chemical industry wastewater is 92.1%, which is 1.34 times of the single ozonation system (68.5%).

[0018] (4) The nitrogen and fluorine co-doped carbon supported cobalt nanomaterial prepared by the method has excellent removal capacity for various pollutants and good anti-interference capacity of coexisting anions.

[0019] (5) The method for preparing the nitrogen and fluorine co-doped carbon supported cobalt nanocatalyst by MOFs crystal growth, PTFE modification and subsequent high-temperature calcination treatment is a simple, low-cost and scalable strategy, and different transition metal-based nanomaterials can be prepared by changing the type of metal salt. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a transmission electron microscope image of Co@FNC prepared in Example 1.

[0021] Figure 2 is an X-ray diffraction test result of the catalyst prepared in Example 1 and Comparative Example 1.

[0022] Figure 3 is a surface contact angle test result of the catalyst prepared in Example 1 and Comparative Examples 1-4.

[0023] Figure 4 is a degradation curve of oxalic acid by catalytic ozonation and a comparison diagram of pseudo-first-order kinetic constants of the catalyst prepared in Example 1 and Comparative Examples 2-4.

[0024] Figure 5 is a degradation curve of oxalic acid by catalytic ozonation and a comparison diagram of pseudo-first-order kinetic constants of the catalyst prepared in Example 1, Comparative Examples 1, 5 and 6.

[0025] Figure 6 is a decomposition performance of ozone in saturated ozone water and self-decomposition performance of the catalyst prepared in Example 1, Comparative Examples 1, 5 and 6 and the corresponding decomposition rate.

[0026] Figure 7 is a degradation curve of oxalic acid by catalytic ozonation and cobalt leaching of the catalyst prepared in Example 1 used for 5 times of reuse.

[0027] Figure 8 is a degradation curve of oxalic acid by catalytic ozonation and pseudo-first-order kinetic constants of the catalyst prepared in Example 1 under the interference of different inorganic salts.

[0028] Figure 9 is an effect diagram of the catalyst prepared in Example 1 used for catalytic ozonation treatment of coal chemical wastewater.

[0029] Figure 10 is a degradation efficiency of oxalic acid by catalytic ozonation of the catalyst prepared in Examples 2-4 and Comparative Examples 8-9.

[0030] Figure 11 The catalyst prepared in Example 1 is applied to the effect diagram of catalyzing ozone treatment of coal chemical wastewater. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0032] Example 1

[0033] The present embodiment provides a preparation method of nitrogen and fluorine co-doped carbon supported cobalt nanomaterial, comprising the following steps:

[0034] (1) Add zinc nitrate hexahydrate (0.3 mol / L) and cobalt nitrate (0.008 mol / L) to 30 mL of methanol, and ultrasonically dissolve to obtain solution A. Similarly, add 2-methylimidazole (80 mmol) to 50 mL of methanol, and ultrasonically dissolve to obtain solution B. Pour solution A into solution B quickly, and after the obtained mixture is stirred vigorously for 1 h, stand for 24 h, then collect the precipitate (Co-ZIF) by centrifugation, methanol washing, and vacuum drying.

[0035] (2) Ultrasonically disperse 0.2 g of the obtained Co-ZIF precipitate in 20 mL of ethanol for 10 min, add 1 mL of polytetrafluoroethylene dispersion liquid (i.e. the mass ratio of Co-ZIF to polytetrafluoroethylene is 1:6.3), stir at room temperature for 8 h, and evaporate ethanol at 80°C to obtain a precursor.

[0036] (3) Place the precursor in a tube furnace, heat at 900°C under the protection of argon for 3 h, and obtain nitrogen and fluorine co-doped carbon supported cobalt nanomaterial (Co@FNC).

[0037] The transmission electron microscope scanning of Example 1 is carried out. Please refer to Figure 1 , the transmission electron microscope observation shows that the polyhedron has a diameter of about 400 nm, and compared with the traditional ZIF-based catalyst, the morphology does not change significantly, but due to the etching of fluorine-containing gas in the pyrolysis process of polytetrafluoroethylene, a hollow structure is formed, and the carbon shell has a thickness of about 40 nm.

[0038] Example 2

[0039] The present embodiment provides a preparation method of nitrogen and fluorine co-doped carbon supported iron nanomaterial, and under the condition that the other conditions of Example 1 are unchanged, the cobalt nitrate in Example 1 (1) is replaced by iron nitrate, and Fe-ZIF is collected to prepare Fe@FNC.

[0040] Example 3

[0041] The present example provides a preparation method of nitrogen and fluorine co-doped carbon supported copper nanomaterial. In the case where other conditions of Example 1 remain unchanged, the cobalt nitrate in Example 1 (1) is replaced with copper nitrate, and Cu-ZIF is collected to prepare Cu@FNC.

[0042] Example 4

[0043] The present example provides a preparation method of nitrogen and fluorine co-doped carbon supported nickel nanomaterial. In the case where other conditions of Example 1 remain unchanged, the cobalt nitrate in Example 1 (1) is replaced with nickel nitrate, and Ni-ZIF is collected to prepare Ni@FNC.

[0044] Comparative Example 1

[0045] As a control, nitrogen-doped carbon supported cobalt nanomaterial is prepared. In the case where other conditions of Example 1 remain unchanged, the Co-ZIF obtained in Example 1 (1) is placed in a tube furnace as a precursor, heated at 900°C under the protection of argon for 2 h, and the obtained material is named Co@NC.

[0046] Example 1 and Comparative Example 1 are subjected to X-ray diffraction test. Please refer to Figure 2 X-ray powder diffraction pattern (Figure 1) confirms the presence of cobalt in Co@NC and Co@FNC nanomaterials, and the diffraction peaks at about 44° and 52° are attributed to the (111) and (200) crystal planes of metallic cobalt (JCPDS 89-4307), respectively.

[0047] Comparative Example 2

[0048] As a control, in the case where other conditions of Example 1 remain unchanged, the amount of polytetrafluoroethylene is changed to 0.1 mL (i.e. the mass ratio of Co-ZIF to polytetrafluoroethylene is 1:0.63), and it is named Co@F 0.1 NC.

[0049] Comparative Example 3

[0050] As a control, in the case where other conditions of Example 1 remain unchanged, the amount of polytetrafluoroethylene is changed to 0.5 mL (i.e. the mass ratio of Co-ZIF to polytetrafluoroethylene is 1:3.15), and it is named Co@F 0.5 NC.

[0051] Comparative Example 4

[0052] As a control, in the case where other conditions of Example 1 remain unchanged, the amount of polytetrafluoroethylene is changed to 2 mL (i.e. the mass ratio of Co-ZIF to polytetrafluoroethylene is 1:12.6), and it is named Co@F2NC.

[0053] Surface contact angle tests were performed on Example 1 and Comparative Examples 1, 2, 4. See Table 1. Figure 3 The contact angle test results show that fluorine modification enhances the hydrophilicity of the material surface, and Co@NC, Co@F1NC, Co@F2NC have better hydrophilicity than NC. 0.1 The surface contact angles of NC, Co@NC, Co@F1NC, Co@F2NC are 113.95, 109.66, 81.31, and 48.72, respectively.

[0054] Comparative Example 5

[0055] As a control, nitrogen-doped nanomaterials were prepared without adding cobalt nitrate under the same conditions as Example 1, and were named NC.

[0056] Comparative Example 6

[0057] As a control, fluorine-modified nitrogen-doped nanomaterials were prepared without adding cobalt nitrate under the same conditions as Example 1, and were named FNC.

[0058] Comparative Example 7

[0059] As a control, nitrogen-doped carbon-supported iron nanomaterials were prepared under the same conditions as Example 2, except that the Fe-ZIF obtained in Example 2 was used as a precursor and placed in a tube furnace and heated at 900°C under the protection of argon for 2 h, and the obtained material was named Fe@NC.

[0060] Comparative Example 8

[0061] As a control, nitrogen-doped carbon-supported iron nanomaterials were prepared under the same conditions as Example 3, except that the Cu-ZIF obtained in Example 3 was used as a precursor and placed in a tube furnace and heated at 900°C under the protection of argon for 2 h, and the obtained material was named Cu@NC.

[0062] Comparative Example 9

[0063] As a control, nitrogen-doped carbon-supported iron nanomaterials were prepared under the same conditions as Example 4, except that the Ni-ZIF obtained in Example 4 was used as a precursor and placed in a tube furnace and heated at 900°C under the protection of argon for 2 h, and the obtained material was named Ni@NC.

[0064] Effect Example 1

[0065] The performance of the catalysts prepared in Example 1 and Comparative Examples 2-4 in heterogeneous catalytic ozonation degradation of oxalic acid was tested.

[0066] The performance test of the nitrogen and fluorine co-doped carbon-supported cobalt nanomaterial catalytic ozonation system (Co@FNC / O3) of the present embodiment is as follows: 250 mL of oxalic acid solution containing 100 mg / L oxalic acid was prepared, and 0.1 g of catalyst was added to the solution, and the solution was stirred at 25°C for 2 h. -1Oxalic acid pollutant solution, pH 3. To the water sample, Co@FNC catalyst prepared in Example 1 was added at 0.025 g, and stirred well and treated by ozone aeration using a titanium alloy aeration head, wherein the ozone gas was generated by an ozone generator using an oxygen source, the gas-phase ozone concentration was 40 mg / L, the flow rate of the ozone gas was 50 mL / min, and after sufficient reaction, the concentration of the remaining oxalic acid in the solution was tested at different reaction times.

[0067] In the same way as described above, the same amount of catalyst prepared in Comparative Examples 2-4 was added to the water sample for comparison. See Table 1 Figure 4 , and the Co@FNC prepared in Example 1 and Comparative Examples 2-4 reduced 24-36% of oxalic acid by adsorption within 30 min, while Co@FNC with different amounts of fluorine doping all achieved more than 95% degradation of oxalic acid in the catalytic ozone oxidation system, and the corresponding pseudo-first-order kinetic constants were 0.05 min -1 , 0.09 min -1 , 0.113 min -1 , and 0.111 min -1 , respectively. In contrast, the removal rate of oxalic acid by ozone oxidation alone was less than 10%.

[0068] Effect Example 2

[0069] The performance of the catalyst prepared in Example 1 and Comparative Examples 1, 5, and 6 in heterogeneous catalytic ozone oxidation degradation of oxalic acid was tested.

[0070] The steps for testing the performance of the catalyst in this example were basically the same as in Example 1, except that the same amount of catalyst prepared in Comparative Examples 1, 5, and 6 was added to the water sample for comparison. See Table 1 Figure 5 , the Co@FNC / O3 system prepared in Example 1 achieved 96.1% removal of oxalic acid within 30 min, and the corresponding pseudo-first-order kinetic constant was 0.113 min -1 , which was 56.5 times, 2.6 times, 3.9 times, and 2.7 times, respectively, of the O3 (1%, 0.002 min -1 ), NC / O3 (23%, 0.043 min -1 ), Co@NC / O3 (61%, 0.029 min -1 ), and FNC / O3 (72%, 0.042 min -1 ) systems alone. This indicates that the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial has excellent performance in catalytic ozonation removal of organic matter.

[0071] Effect Example 3

[0072] The performance of the catalysts prepared in Example 1 and Comparative Examples 1, 5, and 6 in catalyzing the decomposition of ozone in saturated ozone water was tested.

[0073] The performance of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial Co@FNC / O3 of the present embodiment was tested as follows: ozone was injected into a beaker containing 2 L of ultrapure water (pH 3) through a titanium alloy aeration head, and aeration was continued for 30 minutes to prepare a saturated ozone solution. The ozone gas was generated by an ozone generator using an oxygen source, and the concentration of the gaseous ozone was 40 mg / L. The flow rate of the ozone gas was 50 mL / min. 250 mL of the saturated ozone water solution was taken, and 0.025 g of the catalyst prepared in Example 1 was added to the water sample, which was stirred thoroughly to start the reaction. The residual ozone concentration in the solution was tested at different reaction times. Please refer to Figure 6 The self-decomposition rate of ozone in saturated ozone water was 0.022 min -1 . The decomposition rates of different catalysts for O3 followed the order Co@FNC (0.152 min -1 ) > FNC (0.093 min -1 ) > Co@NC (0.082 min -1 ) > NC (0.080 min -1 ), so the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial had the fastest O3 decomposition kinetics.

[0074] Effect Example 4

[0075] The performance of the catalyst prepared in Example 1 in degrading oxalic acid and the cobalt leaching were tested after the catalyst was reused 5 times.

[0076] The performance of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial of the present embodiment was tested in the same way as in Effect Example 1, except that the Co@FNC after the reaction was recovered by vacuum filtration, washed with deionized water, and vacuum dried at 60°C overnight for the next oxalic acid degradation, and this cycle was repeated 5 times. Please refer to Figure 7 When the Co@FNC catalyst was reused 5 times, it still achieved ~80% removal of oxalic acid. The content of the leached cobalt was tested by inductively coupled plasma atomic emission spectrometry, and the results showed that the cobalt leaching was maintained below 0.2 mg / L. Therefore, Co@FNC has good stability.

[0077] Effect Example 5

[0078] The anti-interference ability of the catalyst prepared in Example 1 for different inorganic salt anions was tested.

[0079] The performance test steps of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial of the embodiment are basically the same as those of effect example 1, except that 10 mM NaCl, Na2SO4 and Na2PO4 are respectively added to the solution before the catalyst is added. Please refer to Figure 8 In the presence of various coexisting anions (Cl - , SO4 2- and PO4 2- ), Co@FNC / O3 still maintains high activity, and the removal efficiency of oxalic acid can still reach more than 90%. Therefore, Co@FNC has good anti-coexisting anion interference ability.

[0080] Effect example 6

[0081] The catalyst prepared in test example 1 is tested for the ability to catalyze ozone oxidation treatment of different pollutants.

[0082] The performance test steps of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial of the embodiment are basically the same as those of effect example 1, except that 10 mM NaCl, Na2SO4 and Na2PO4 are respectively added to the solution before the catalyst is added. Please refer to Figure 9 The degradation rate of p-aminophenol reached 100% in 15 min, and the degradation rates of phenol and nitrophenol also reached more than 90%. Therefore, the Co@FNC / O3 system exhibits excellent removal ability for different pollutants.

[0083] Effect example 7

[0084] The performance test steps of the catalyst of the embodiment are basically the same as those of effect example 1, except that the same amount of catalysts prepared in examples 2-4 and comparative examples 7-9 are added to the water sample for comparison. Please refer to Figure 10 , nitrogen-doped carbon supported iron, copper and nickel catalysts and nitrogen and fluorine co-doped carbon supported iron, copper and nickel catalysts are prepared by replacing the metal precursors. The results show that the nitrogen and fluorine co-doped carbon supported iron (Fe@FNC), copper (Cu@FNC) and nickel (Ni@FNC) catalysts catalyze the ozonation degradation of oxalic acid, and the oxalic acid removal efficiency is 79.84%, 73.63% and 64.49% respectively in 30 min, which is better than that of the nitrogen-doped carbon supported metal-based carbon material, and the oxalic acid removal efficiency of Fe@NC, Cu@NC and Ni@NC is 31.71%, 14.01% and 13.09% respectively. Therefore, the method proposed by the application has strong expandability.

[0085] Effect example 8

[0086] The testing procedures for the nitrogen-fluorine co-doped carbon-supported cobalt nanomaterials in this implementation case regarding their treatment efficiency for actual coal chemical wastewater are basically the same as in Example 1, except that the wastewater sample used is coal chemical wastewater with an initial COD of 368.8 mg / L and a TOC of 140 mg / L. Please refer to [link to relevant documentation]. Figure 11 The Co@FNC prepared in Example 1 can achieve 50% TOC removal after 120 min of catalytic ozonation treatment. Figure 11 a). By analyzing the ozone concentration in the O3 and Co@FNC / O3 systems alone during wastewater treatment ( Figure 11 b) The ozone utilization rate of the system was calculated based on the detection results. Figure 11 c). The concentration of gaseous ozone at the outlet and the residual ozone concentration in the solution in the Co@FNC / O3 system are both lower than those in the O3 system alone. The corresponding ozone utilization rates were calculated to be 92.1% and 68%, respectively, indicating that the prepared Co@FNC catalyst has good catalytic ozone activity and can effectively promote the decomposition of ozone molecules.

[0087] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for purifying water by catalytic ozonation using nitrogen and fluorine co-doped carbon supported cobalt nanomaterials, characterized in that, The preparation method of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial comprises the following steps: (1) Dissolve a zinc salt and a cobalt salt in a methanol solution to obtain a solution A; dissolve 2-methylimidazole in a methanol solution to obtain a solution B; pour the solution A into the solution B to obtain a mixed solution, then perform vigorous stirring and standing, and through centrifugation and methanol washing, a precipitate is obtained after drying; (2) Ultrasonically disperse the precipitate in an ethanol solution, add a polytetrafluoroethylene dispersion liquid as a fluorine source, fully stir and mix the obtained mixture, and then perform evaporation treatment to obtain a precursor; (3) Place the precursor obtained in (2) in a tube furnace, perform heat treatment under an inert atmosphere, and after natural cooling to room temperature, the cobalt, nitrogen and fluorine co-doped nanocarbon material is obtained.

2. The production method according to claim 1, characterized by, In step (1), the cobalt salt is any one of cobalt acetylacetonate, cobalt nitrate and cobalt acetate.

3. The production method according to claim 1, characterized by, In step (1), the concentration of the 2-methylimidazole is 0.4-4 mol / L; the concentration of the zinc salt is 0.01-0.5 mol / L; and the concentration of the cobalt salt is 0.001-0.5 mol / L.

4. The method of claim 1, wherein, In step (2), the mass fraction of the polytetrafluoroethylene dispersion liquid is 60%; and the mass ratio of the precipitate to the polytetrafluoroethylene is 1:0.63-1:50.

4.

5. The preparation method according to claim 1, characterized in that, In step (3), the inert atmosphere is Ar or N2, and the flow rate is 50-200 mL / min; the heat treatment is as follows: heating to 800-1000℃ at a heating rate of 5℃ / min, and keeping for 3h, and then naturally cooling to room temperature.

6. The water purification method based on nitrogen-fluorine co-doped carbon-supported cobalt nanomaterials for catalytic ozone oxidation according to claim 1, characterized in that, 0.01-5 g / L of the nitrogen and fluorine co-doped carbon supported cobalt nanomaterial is added to a solution containing organic pollutants, fully stirred, then an ozone generator is connected, and a mixed gas of oxygen and ozone is introduced into the wastewater through an aeration head at a flow rate of 10-1000 mL / min, wherein the concentration of the ozone is 5-100 mg / L, and the reaction is started by stirring at room temperature.

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