Cobalt-loaded magnesium-manganese composite oxide material as well as preparation method and application thereof

Abstract

The invention discloses a cobalt-loaded magnesium-manganese composite oxide material and a preparation method thereof. The preparation method comprises the following steps: (1) synthesizing an MgMn-MOF precursor by adopting a solvothermal reaction; and (2) impregnating the MgMn-MOF precursor with a soluble cobalt salt solution, drying the precursor, and calcining the precursor in an inert atmosphere at 500-800 DEG C for 2-3 h to obtain the cobalt-loaded magnesium-manganese composite oxide material Co-MgMn-C. The cobalt-loaded magnesium-manganese composite oxide material can more efficiently catalyze ozone to be decomposed into active free radicals, and has excellent stability. The invention also discloses an application of the cobalt-loaded magnesium-manganese composite oxide material in catalytic ozonation degradation of organic pollutants in water.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a cobalt-loaded magnesium-manganese composite oxide material, its preparation method, and its application. Background Technology

[0002] In recent years, research on advanced oxidation technologies (AOPs) for degrading organic pollutants in water has received increasing attention. AOPs mainly include ozone oxidation, photocatalytic oxidation, electrochemical oxidation, Fenton oxidation, ultrasonic oxidation, and wet oxidation. Among these, ozone has advantages such as strong oxidizing properties, excellent bactericidal and decolorizing effects, and no secondary pollution.

[0003] However, ozone oxidation alone suffers from problems such as low mineralization efficiency of organic pollutants, high reaction selectivity, high operating costs, and the potential generation of toxic intermediates. To overcome these shortcomings, catalytic ozone oxidation technology has emerged, which introduces a catalyst to activate ozone molecules, converting them into more reactive oxygen species with stronger oxidizing power (such as hydroxyl radicals •OH and superoxide radicals •O2). - Singlet oxygen 1 (O2, etc.), thereby achieving efficient degradation and mineralization of pollutants.

[0004] Heterogeneous catalytic ozonation can significantly improve ozone oxidation efficiency, among which metal oxides have attracted attention due to their high efficiency and ease of operation. Numerous studies have been reported on the application of metal oxides, metal-supported catalysts, and carbon materials as catalysts for the ozone oxidation of organic compounds.

[0005] Chinese patent document CN116037209A discloses an ozone oxidation catalyst, which is a magnesium-manganese binary metal-organic framework catalyst obtained by calcining a Mg-MOF containing Mn element through an equal-volume impregnation method. Chinese patent document CN102161526A discloses the application of magnesium oxide-supported cobalt-iron magnetic nanomaterials, specifically for the degradation of the organic pollutant Orange II in wastewater. Both of these catalysts have limited degradation capabilities for organic matter.

[0006] In the adsorption-catalytic ozone oxidation system, the adsorption capacity of the catalyst and the catalytic active sites are often in competition. While high adsorption can enrich organic matter on the catalyst surface and shorten the free radical transport distance, excessive adsorption can lead to the occupation of active sites or blockage of pores, thus inhibiting contact with ozone and the initiation of subsequent chain reactions. Therefore, the system's ability to remove pollutants can be improved by enhancing the catalytic activity of the catalyst. This requires us to conduct surface modification studies on the catalyst using various methods to achieve enhanced removal of pollutants from water.

[0007] Based on the mechanism of heterogeneous catalytic ozone oxidation and the characteristics required of heterogeneous catalysts, this invention proposes a cobalt-loaded magnesium-manganese composite oxide material and its preparation method. Introducing metallic cobalt to dope the main catalyst is an effective means of controlling its electronic structure, increasing defect sites, and enhancing its redox capabilities. Cobalt, as a strong cobalt-containing alloy, is a key component in this process. 2 + / Co 3+ Transition metals of redox pairs, when doped, have been shown to significantly enhance the ozone activation performance of catalysts. Summary of the Invention

[0008] This invention provides a cobalt-loaded magnesium-manganese composite oxide material and its preparation method. This material can more efficiently catalyze the decomposition of ozone into active free radicals and has excellent stability.

[0009] The technical solution of the present invention is as follows: A method for preparing a cobalt-loaded magnesium-manganese composite oxide material includes the following steps: (1) The MgMn-MOF precursor was synthesized by solvothermal reaction; (2) Soluble cobalt salt solution is impregnated onto MgMn-MOF precursor, dried, and then calcined at 500-800℃ for 2-3 h under an inert atmosphere to obtain cobalt-loaded magnesium-manganese composite oxide material Co-MgMn-C.

[0010] In the Co-MgMn-C material of this invention, Mg and Mn exist in the form of oxides, while Co exists in the form of an element. MgO provides a stable alkaline environment and structural support, MnO2 provides the main ozone decomposition active sites and multivalent redox pairs, and the introduction of Co modifies the electronic structure of manganese oxides, further promoting electron transfer and strengthening Co. 2+ / Co 3+ With Mn 3+ / Mn 4+ The coupling between redox cycles enables more efficient catalysis of ozone decomposition into active free radicals. In the Co-MgMn-C material of this invention, the synergistic effect of magnesium, manganese, and cobalt allows the Co-MgMn-C material to more efficiently catalyze the decomposition of ozone into active free radicals and exhibits excellent stability.

[0011] Preferably, step (1) includes: dissolving magnesium salt, manganese salt and organic ligand in an organic solvent to form a mixed solution; carrying out a solvothermal reaction of the mixed solution in a reaction vessel; and then separating, washing, drying and grinding the resulting reaction product to obtain the MgMn-MOF precursor.

[0012] More preferably, the molar ratio of magnesium salt to manganese salt is 1~2:1.

[0013] Preferably, the organic ligand is terephthalic acid; the total amount of magnesium salt and manganese salt to the molar ratio of organic ligand is 1~2:1.

[0014] More preferably, the organic solvent is a mixture of N,N-dimethylformamide and anhydrous ethanol, wherein the volume ratio of N,N-dimethylformamide to anhydrous ethanol in the mixture is 1 to 5:1.

[0015] A further preferred embodiment is a solvothermal reaction time of 12 hours.

[0016] Preferably, in step (2), an equal volume of soluble cobalt salt solution is impregnated onto the MgMn-MOF precursor, and the cobalt doping amount is 3~10%.

[0017] Equal volume impregnation refers to the impregnation method in which the volume of the impregnation liquid is equal to the pore volume of the solid support to prepare the supported catalyst.

[0018] Cobalt doping level The calculation formula is: in, The mass of the impregnated Co element; The mass is the MgMn-MOF precursor.

[0019] More preferably, the cobalt doping amount is 5-10%.

[0020] Preferably, in step (2), calcination is carried out under an inert atmosphere, with the temperature increased to 500-800℃ at a rate of 3-7℃ / min and held for 2-3 h.

[0021] More preferably, in step (2), the calcination temperature is 500-600 ℃.

[0022] The present invention also provides a cobalt-loaded magnesium-manganese composite oxide material Co-MgMn-C prepared by the above preparation method.

[0023] Preferably, in the Co-MgMn-C material, Mg and Mn exist in the form of oxides, and Co exists in the form of an element.

[0024] More preferably, the X-ray diffraction pattern of the Co-MgMn-C material has characteristic diffraction peaks at 2θ of 35.8°, 42.0°, 44.2°, 51.5°, 61.4°, and 75.8°.

[0025] The present invention also provides an application of the aforementioned cobalt-loaded magnesium-manganese composite oxide material in the catalytic ozone oxidation degradation of organic pollutants in water.

[0026] Preferably, the application includes: adding the cobalt-loaded magnesium-manganese composite oxide material to wastewater containing organic pollutants, and introducing ozone-containing gas for catalytic degradation; The mass-to-volume ratio of cobalt-supported magnesium-manganese composite oxide catalyst to wastewater was (0.05~0.08) g: 250 mL.

[0027] Preferably, the initial pH value of the wastewater is 6 to 8.

[0028] Preferably, the ozone injection rate is 2~25 mg / min.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Compared with the unsupported cobalt MgMn-C catalyst, the Co-MgMn-C catalyst of the present invention can catalyze the generation of more free radicals from ozone, thereby accelerating the degradation of organic pollutants.

[0030] (2) The novel Co-MgMn-C catalyst prepared by the present invention enriches organic matter on the catalyst surface due to adsorption, thereby improving the utilization rate of free radicals on the catalyst surface.

[0031] (2) The novel Co-MgMn-C catalyst prepared by this invention has a stable active center structure, is not easily affected by inorganic ions in the environment, uses inexpensive raw materials, has a simple preparation method, and does not generate secondary pollution. The Co-MgMn-C catalyst of this invention can be reused multiple times and still maintains high catalytic activity after multiple reuses. Attached Figure Description

[0032] Figure 1 These are the XRD patterns of the catalysts prepared in Example 3 and Comparative Example 1.

[0033] Figure 2 These are scanning electron microscope (SEM) images of the catalysts prepared in Example 3 and Comparative Example 1.

[0034] Figure 3 This is an EDS image of the catalyst prepared in Example 3, showing its elemental distribution.

[0035] Figure 4 Examples 1-3, Comparative Example 1, and the degradation effect of ozone alone on acetic acid under catalyst-free conditions are shown.

[0036] Figure 5 Examples 1-3, Comparative Examples 1 and 2, and the degradation effect of ozone alone on phenol under catalyst-free conditions are shown.

[0037] Figure 6These are the effect diagrams of catalytic ozone degradation of phenol in the presence of different inorganic ions in Example 3 and Comparative Example 1.

[0038] Figure 7 This is a graph showing the change in phenol removal rate during five cycles of use for Examples 3, 1, and 2. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not limit it in any way.

[0040] Examples 1-3 10 mmol Mg(NO3)2•6H2O and 5 mmol Mn(NO3)2•4H2O, along with 7.5 mmol terephthalic acid, were sonicated until completely dissolved in 75 mL of a mixed solvent of N,N-dimethylformamide and anhydrous ethanol (N,N-dimethylformamide and anhydrous ethanol, volume ratio 4:1). The resulting solution was placed in a sealed hydrothermal reactor and heated in a vacuum oven at 120 °C for 12 h. After cooling to room temperature, the resulting precipitate was centrifuged and washed three times with anhydrous ethanol. It was then dried at 80 °C for 8 h to obtain the MgMn-MOF precursor.

[0041] Co(NO3)2·6H2O was loaded onto MgMn-MOF precursor powder as a cobalt source using an equal-volume impregnation method. After impregnation for 18 h, the powder was dried in a vacuum oven, thoroughly ground, and then placed in a tube furnace under nitrogen gas and calcined at 550 °C for 2 h at a heating rate of 5 °C / min to obtain x%Co-MgMn-C (when the impregnation amount is x%).

[0042] Preliminary experiments determined that the saturated impregnation amount of the MgMn-MOF precursor powder was 1.3 ml / g. Cobalt-containing solutions with different contents were prepared by dissolving an appropriate amount of Co(NO3)2·6H2O in 1.3 ml of anhydrous ethanol beforehand for impregnation. The cobalt loading was adjusted by changing the concentration of the cobalt-containing solution.

[0043] In Examples 1-3, x% of Co-MgMn-C is 3%, 5%, and 8%, respectively.

[0044] When doping cobalt using the equal-volume impregnation method, x% = mass of impregnated Co element / (mass of impregnated Co element + mass of MgMn-MOF precursor). For example, when the impregnation amount is 8%, 0.43 g of Co(NO3)2•6H2O is loaded onto 1 g of MgMn-MOF precursor powder as a cobalt source using the equal-volume impregnation method.

[0045] Comparative Example 1 Methods for preparing catalysts include: 10 mmol Mg(NO3)2•6H2O, 5 mmol Mn(NO3)2•4H2O, and 7.5 mmol terephthalic acid were dissolved under ultrasonic conditions in 75 mL of a mixed solvent of N,N-dimethylformamide and anhydrous ethanol (N,N-dimethylformamide and anhydrous ethanol volume ratio 4:1). The resulting solution was placed in a sealed hydrothermal reactor and heated in a vacuum oven at 120 °C for 12 h. After cooling to room temperature, the precipitate was centrifuged and washed three times with anhydrous ethanol. It was then dried at 80 °C for 8 h to obtain the MgMn-MOF precursor. The precursor powder was ground uniformly in a mortar and calcined in a tube furnace at 550 °C for 2 h under nitrogen atmosphere at a heating rate of 5 °C / min. The resulting product was MgMn-C.

[0046] Comparative Example 2 Methods for preparing catalysts include: 10 mmol Mg(NO3)2•6H2O, 5 mmol Mn(NO3)2•4H2O, 1.3 mmol Co(NO3)2·6H2O, and 7.5 mmol terephthalic acid were dissolved under ultrasonic conditions in 75 mL of a mixed solvent of N,N-dimethylformamide and anhydrous ethanol (N,N-dimethylformamide and anhydrous ethanol volume ratio 4:1). The resulting solution was placed in a sealed hydrothermal reactor and heated in a vacuum oven at 120 °C for 12 h. After cooling to room temperature, the precipitate was centrifuged and washed three times with anhydrous ethanol. It was then dried at 80 °C for 8 h to obtain the MgMnCo-MOF precursor. The precursor powder was ground uniformly in a mortar and calcined in a tube furnace at 550 °C for 2 h with nitrogen gas introduced and a heating rate of 5 °C / min. The resulting product was MgMnCo-C.

[0047] Test Example 1 The catalysts prepared in Example 3 and Comparative Example 1 were characterized using a Rigaku Ultima IV intelligent multi-functional X-ray diffractometer. The test conditions were as follows: target source Cu Kα, scan rate of 2° / min, and scan angle of 10~80°.

[0048] Characterization results as follows Figure 1 As shown, (MgO) 0.59 (MnO) 0.41 The (111), (200), and (220) crystal planes appear in the XRD pattern of MgMn-C, indicating that the magnesium-manganese composite material was successfully prepared.

[0049] After impregnating MgMn-MOF precursor powder with metallic cobalt and calcining, XRD diffraction data showed that the phase composition of the 8% Co-MgMn-C catalyst underwent significant changes. First, obvious cobalt elemental diffraction peaks were observed at 2θ = 44.3° and 51.6°, indicating that the cobalt species were reduced to the metallic state during calcination. Simultaneously, the diffraction patterns of the support oxide showed changes in the relative intensities of its characteristic peaks. The intensity of the (200) diffraction peak in the magnesium-manganese composite oxide decreased significantly, while the (220) half-width increased, indicating that the crystallinity or grain size of the support changed due to the introduction of cobalt.

[0050] Test Example 2 The catalysts prepared in Example 3 and Comparative Example 1 were characterized using a ZEISS Sigma 300 scanning electron microscope (SEM). A small amount of sample was directly adhered to a conductive adhesive and sputtered with gold using a Quorum SC7620 sputtering system at 10 mA. Subsequently, the ZEISS Sigma 300 was used to image the sample morphology and perform energy dispersive spectroscopy (EDS) mapping. The accelerating voltage for morphology imaging was 3 kV, and for EDS mapping, it was 15 kV. An SE2 secondary electron detector was used. SEM images of MgMn-C are as follows Figure 2 As shown in (a), at the current magnification, MgMn-C exhibits a highly aggregated blocky structure. After impregnating the precursor powder with metallic cobalt and calcining, the SEM image is as follows. Figure 2 As shown in (b), the morphology of the 8% Co-MgMn-C catalyst changes significantly. At higher magnification, the surface of the catalyst appears to be fluffy and porous, and the metallic Co nanoparticles are enriched on the surface of the material.

[0051] like Figure 3 The EDS image shown indicates that the uniform distribution of Mg, Mn, and Co elements on the 8% Co-MgMn-C surface suggests that the composite material has been successfully prepared.

[0052] Application Example 1 Acetic acid is the final product of the chemical oxidation process for degrading organic matter. When large quantities of acetic acid are discharged into water bodies, it lowers the pH value, increases the organic matter content, and leads to eutrophication, which in turn causes the proliferation of algae, zooplankton, and other organisms, resulting in water quality deterioration. Therefore, the x%Co-MgMn-C catalysts of Examples 1-3 and the catalyst of Comparative Example 1 are used for the catalytic ozonolysis degradation of acetic acid.

[0053] Catalytic ozone oxidation was performed in a bubble column reactor at ambient temperature and pressure. Ozone was generated from oxygen using a laboratory ozone generator (Guangzhou Zhenao Ozone Equipment Co., Ltd.). During the reaction, 250 mL of acetic acid at 20 mg / L was added to the reactor to adjust the initial pH of the solution to 7.2. The catalyst dosage was 0.3 g / L, and the ozone dosage was 20 mg / min. Every 3 min, 15 mL of water sample was taken from the reactor and filtered through a 0.45 μm microporous membrane to remove the catalyst. Then, 1 mL of the filtrate was injected into a liquid chromatography vial, and the concentration of residual acetic acid in the solution was detected by high performance liquid chromatography (HPLC, Ultimate 3000).

[0054] This application example investigated the degradation effects of x% Co-MgMn-C in Examples 1-3, the catalyst in Comparative Example 1, and ozone alone on acetic acid. The results are as follows: Figure 4 As shown, by Figure 4 It was found that catalysts with different proportions of cobalt doping all exhibited good catalytic degradation effects on acetic acid. Among them, the 8% Co-MgMn-C catalyst showed the highest efficiency in degrading acetic acid, achieving a degradation rate of 82.8% after 9 minutes of reaction. The removal rate of acetic acid in the solution using the catalysts of Examples 1-3 was significantly higher than that of the comparative catalyst, indicating that cobalt can be relatively uniformly distributed on the porous MgMn-MOF precursor through the equal-volume impregnation method. After calcination, cobalt is highly dispersed in the carbon matrix in the form of nanoparticles or clusters, exposing more active surface area and significantly increasing the contact sites with ozone.

[0055] Application Example 2 Adsorption experiments were conducted at ambient temperature and pressure under ozone-free conditions (oxygen only). All ozonation experiments were carried out in a semi-continuous reaction system using a stirred ozonation reactor to degrade phenol. Ozone was generated by a laboratory ozone generator (Guangzhou Zhenao Ozone Equipment Co., Ltd.) using oxygen as the feed gas. During the reaction, 250 mL of phenol at a concentration of 20 mg / L was added to the reactor to adjust the initial pH of the solution to 7.2. The catalyst dosage was 0.2 g / L. Ozone was continuously introduced while stirring constantly at a dosage of 1.3 mg / min. Every 2 minutes, 15 mL of water was taken from the reactor and filtered through a 0.45 μm microporous membrane to remove the catalyst. Then, 1 mL of the filtrate was injected into a liquid chromatography vial, and the concentration of residual phenol in the solution was detected by high-performance liquid chromatography (HPLC, Ultimate 3000).

[0056] This application example investigated the adsorption rate of phenol by the x% Co-MgMn-C catalysts of Examples 1-3 and the catalysts of Comparative Examples 1 and 2. The results are shown in Table 1.

[0057] Table 1. Adsorption rate of catalyst for phenol This application example also investigated the degradation effects of the cobalt-supported magnesium-manganese composite oxide catalysts of Examples 1-3, as well as the catalysts of Comparative Examples 1 and 2, on phenol under ozone-only conditions. The results are as follows: Figure 5 As shown, by Figure 5 It can be seen that the synthesized novel catalysts x%Co-MgMn-C can degrade 97% or more of phenol within 9 min, while the catalysts of Comparative Examples 1 and 2 have phenol removal rates of 88.4% and 92.9%, respectively. This indicates that the cobalt-supported magnesium-manganese composite oxide catalysts of Examples 1-3 have significantly stronger catalytic activity than the catalysts of Comparative Examples 1 and 2.

[0058] The MgMnCo-C catalyst synthesized in Comparative Example 2 has a stronger adsorption capacity than the Co-MgMn-C catalysts synthesized in Examples 1-3. However, the cobalt species are uniformly embedded in the bulk phase, and some active sites are buried, making it difficult to contact ozone and pollutants, resulting in lower catalytic efficiency.

[0059] After high-temperature calcination of cobalt loaded onto the MgMn-MOF precursor, the Co-MgMn-C catalyst still retains a certain degree of adsorption of organic matter, and the degradation efficiency is improved. This demonstrates that the introduction of cobalt via the equal-volume impregnation method increases the surface active sites, enhances the catalytic oxidation process while maintaining adsorption, lowers the activation energy, and improves ozone activation efficiency.

[0060] Application Example 3 In the systems of 8% Co-MgMn-C and MgMn-C catalyzing the ozone oxidation of phenol, inorganic salts containing different ions were added respectively. , , The concentration of inorganic salts was 2 mmol / L, and other experimental conditions were the same as in Application Example 2.

[0061] The purpose of this application example is to investigate the effects of 8% Co-MgMn-C and MgMn-C catalysts on the degradation efficiency of phenol in environments containing different inorganic ions. It is usually used as a substituent for hydroxyl groups on the catalyst surface, and therefore has a certain impact on the active sites on the catalyst surface. It easily competes with target organic compounds for adsorption, interfering with the catalytic process; It is one of the most common inorganic anions in conventional wastewater and high-salt wastewater. It can scavenge hydroxyl radicals generated during ozone oxidation, thereby reducing the degradation efficiency of organic pollutants.

[0062] like Figure 6 As shown, and The MgMn-C catalyst exhibits a significant inhibitory effect on the ozone degradation of phenol, indicating that the hydroxyl groups on the MgMn-C catalytic surface are affected. The impact is significant, and at the same time, active free radicals in the bulk phase are affected. The scavenging effect reduces degradation efficiency. In contrast, most inorganic ions did not significantly inhibit the degradation efficiency of phenol, the target pollutant of 8% Co-MgMn-C, and the degradation efficiency remained stable and high. The reason for this is that the introduction of cobalt promotes the surface-mediated reaction pathway. Cobalt has strong electron transfer capabilities, and more active sites in full contact with ozone not only generate hydroxyl radicals but also produce more active radicals through chain reactions. Such as singlet oxygen 1 O2 Therefore, even in water containing inorganic ions, 8% Co-MgMn-C can still maintain a high oxidation efficiency. Thus, the catalyst of this invention exhibits good resistance to ion interference and strong environmental adaptability in ozone catalysis systems, which is of great significance for promoting the application of catalytic ozone technology in practical ion-containing wastewater treatment, demonstrating the potential of the catalyst to maintain stable performance under complex water quality conditions.

[0063] Application Example 4 The MgMn-C, MgMnCo-C, and 8%Co-MgMn-C catalysts recovered from the reaction in Application Example 2 were recovered by filtration, washed several times with deionized water, dried at 80 °C, and used for the next catalytic ozone degradation of phenol experiment. This process was repeated 5 times. Other experimental conditions remained the same as in Application Example 2.

[0064] The results are as follows Figure 7 As shown, the phenol degradation rate of the 8% Co-MgMn-C catalyst remained at 91.7% after the 5th cycle, which is much higher than that of MgMnCo-C (78.5%) and MgMn-C (69.3%), demonstrating its excellent stability.

[0065] The embodiments described above provide a detailed explanation of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, additions, and equivalent substitutions made within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a cobalt-loaded magnesium-manganese composite oxide material, characterized in that, Includes the following steps: (1) The MgMn-MOF precursor was synthesized by solvothermal reaction; (2) Soluble cobalt salt solution is impregnated onto MgMn-MOF precursor, dried, and then calcined at 500-800 °C for 2-3 h under an inert atmosphere to obtain cobalt-loaded magnesium-manganese composite oxide material Co-MgMn-C.

2. The method for preparing cobalt-loaded magnesium-manganese composite oxide material according to claim 1, characterized in that, Step (1) includes: dissolving magnesium salt, manganese salt and organic ligand in an organic solvent to form a mixed solution; carrying out a solvothermal reaction of the mixed solution in a reaction vessel; and then separating, washing, drying and grinding the resulting reaction product to obtain the MgMn-MOF precursor.

3. The method for preparing cobalt-loaded magnesium-manganese composite oxide material according to claim 2, characterized in that, The molar ratio of magnesium salt to manganese salt is 1~2:

1.

4. The method for preparing cobalt-loaded magnesium-manganese composite oxide material according to claim 2, characterized in that, The total amount of magnesium salts and manganese salts is in a molar ratio of 1 to 2:1 to organic ligands.

5. The method for preparing cobalt-loaded magnesium-manganese composite oxide material according to claim 1, characterized in that, In step (2), an equal volume of soluble cobalt salt solution is impregnated onto the MgMn-MOF precursor, with a cobalt doping amount of 3~10%.

6. The method for preparing the cobalt-loaded magnesium-manganese composite oxide material according to claim 1, characterized in that, In step (2), calcination is carried out under an inert atmosphere, with the temperature increased to 500-800 ℃ at a rate of 3-7 ℃ / min and held for 2-3 h.

7. A cobalt-loaded magnesium-manganese composite oxide material prepared by the preparation method according to any one of claims 1-6.

8. The cobalt-loaded magnesium-manganese composite oxide material according to claim 7, characterized in that, In the cobalt-loaded magnesium-manganese composite oxide material, Mg and Mn exist in the form of oxides, while Co exists in the form of elemental form.

9. The cobalt-loaded magnesium-manganese composite oxide material according to claim 7 or 8, characterized in that, The X-ray diffraction pattern of the cobalt-loaded magnesium-manganese composite oxide material has characteristic diffraction peaks at 2θ of 35.8°, 42.0°, 44.2°, 51.5°, 61.4°, and 75.8°.

10. The application of a cobalt-loaded magnesium-manganese composite oxide material according to any one of claims 7-9 in the catalytic ozone oxidation degradation of organic pollutants in water.

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