Method for preparing MnCo2O4 catalyst from phosphate radical modified precursor and application of MnCo2O4 catalyst

Abstract

The invention provides a method for preparing a MnCo2O4 catalyst from a phosphate radical modified precursor and application of the MnCo2O4 catalyst, uniform doping of phosphate radical ions in a MnCo2O4 crystal is realized through a synergistic effect of molecular modification and subsequent calcination of a phosphate radical functional group on a cobalt-manganese hydroxide precursor, so that the defects of surface modification are fundamentally overcome, and the application range of the MnCo2O4 catalyst is widened. The method has the advantages of simple preparation process, short reaction time, mild conditions, strong controllability and good repeatability, and is suitable for the fields of efficient water treatment and environmental restoration. Phosphate radical impregnation is carried out at the cobalt manganese hydroxide precursor stage, so that phosphate radicals enter an MnCo2O4 spinel bulk phase structure in the subsequent calcination process, stable bulk phase modification is realized, and the thermal stability and structural integrity of the material are remarkably improved; phosphate radicals have an adjusting effect on a metal cation coordination environment, valence optimization of Mn and Co can be induced in the calcination process, the proportion of Mn < 3 + > / Mn < 4 + > and balance of Co < 2 + > / Co < 3 + > are improved, and the material has more high-activity sites capable of participating in persulfate activation reaction.

Description

Technical Field

[0001] This invention relates to the field of catalytic oxidation of water, and more specifically, to a method for preparing MnCo2O4 catalyst from a phosphate-modified precursor and its application. Background Technology

[0002] Sulfadiazine (SMZ), a widely used sulfonamide antibiotic for treating human and animal diseases, is structurally stable and difficult to metabolize, easily forming residues in aquatic environments and accumulating in ecosystems, causing serious pollution. With the increasing prominence of emerging pollutants in water bodies, the demand for research into treatment technologies for recalcitrant organic pollutants is constantly increasing. Persulfate advanced oxidation technologies (PS-AOPs) show great potential in the removal of organic pollutants due to their wide applicable pH range, strong oxidizing capacity, and high treatment efficiency. Its core lies in activating persulfate with a highly efficient catalyst to generate sulfate radicals (SO4). − This technology aims to achieve the complete mineralization of recalcitrant pollutants. Therefore, developing persulfate-activated catalysts with high activity, excellent stability, and regenerability is crucial for promoting the practical application of this technology.

[0003] Spinel catalysts, with their unique three-dimensional lattice, high thermal / chemical stability, and excellent electron transport properties, have become one of the most promising catalytic materials in heterogeneous PS-AOPs. However, traditional spinel catalysts still face problems such as particle agglomeration, low specific surface area, and limited active sites, which severely restrict their catalytic performance. Furthermore, catalyst deactivation is easily caused by factors such as contaminant adsorption and structural damage during use, affecting their recyclability. Therefore, how to optimize the electronic structure and improve the structural stability of catalysts through structural regulation has become a current research hotspot and challenge. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing MnCo2O4 catalyst from phosphate-modified precursor and its application, so as to solve the above problems.

[0005] The present invention adopts the following solution: This application provides a method for preparing MnCo2O4 catalyst from a phosphate-modified precursor, comprising the following steps: S1: Preparation containing Co 2+ Mn 2+ A precursor mixture solution; wherein at least one cobalt salt, at least one manganese salt, a fluoride source and a carbon source are dissolved in deionized water and stirred evenly, and the resulting mixture is transferred to a closed hydrothermal reactor for hydrothermal reaction to obtain a cobalt manganese hydroxide precursor; S2: The cobalt manganese hydroxide precursor is immersed in an aqueous solution containing phosphate source and stirred, then centrifuged, washed and dried to obtain a phosphate-modified intermediate product; S3: The intermediate product is calcined in an oxygen or air atmosphere to obtain bulk phosphate-modified MnCo2O4 material.

[0006] As a further improvement, in step S1, the cobalt salt is cobalt nitrate, the manganese salt is manganese nitrate, the fluoride source is NH4F, and the carbon source is urea.

[0007] As a further improvement, the mixture is obtained by dissolving 4 mmol Co(NO3)2, 2 mmol Mn(NO3)2, 20 mmol NH4F and 50 mmol Co(NH2)2 in 50 mL of deionized water and stirring until homogeneous.

[0008] As a further improvement, in step S1, the temperature of the hydrothermal reaction is 120°C and the reaction time is 5 hours; or the temperature and time are adjusted within a range close to each other to achieve the same precursor morphology and crystallinity; preferably, the temperature range is 100 to 150°C and the time range is 2 to 12 hours.

[0009] As a further improvement, in step S2, the phosphate source used is selected from at least one of the following: (NH4)3PO4, (NaPO3)6, Na6P4O 13 The initial impregnation solution contains Na4P2O7 or other soluble phosphate compounds; the molar concentration n of the initial impregnation solution is 0.1, 0.3, 0.5 or 0.7 M, or in the range of 0.05 to 1.0 M; the impregnation time and stirring intensity are determined according to the required surface / bulk phase doping degree; wherein, the preferred stirring time at room temperature is 1 to 6 hours.

[0010] As a further improvement, in step S3, calcination is carried out in air or near-air atmosphere, with a preferred calcination temperature of 400°C and a preferred calcination time of 3 hours; or it is carried out in the range of 350 to 500°C and 1 to 6 hours to obtain the target crystalline phase and specific surface area.

[0011] As a further improvement, the bulk phosphate-modified MnCo2O4 material is phosphate-modified spinel-type MnCo2O4, denoted as nPO4-MnCo2O4; where n indicates that the molar concentration of phosphate source in the initial impregnation solution in step S2 is 0.1, 0.3, 0.5, or 0.7 M; the material has detectable phosphate modification or doping in the crystal lattice or in interstitial spaces / surfaces, and retains the spinel structure of the MnCo2O4 bulk material. This application also provides a bulk phosphate-modified MnCo2O4 catalyst material, which is prepared according to the above-described method for preparing MnCo2O4 catalyst from phosphate-modified precursors.

[0012] This application also provides the application of the bulk phosphate-modified MnCo2O4 catalyst material in the activation of persulfate to degrade organic pollutants. The catalyst material is used to activate persulfate or permonosulfate oxidants (preferably perdisulfate, permonosulfate / permonosulfate or other persulfate derivatives) to degrade sulfonamide antibiotics in the aqueous phase, preferably sulfadiazine, sulfamethoxazole and other target organic pollutants.

[0013] As a further improvement, the residual amount of the sulfonamide compounds was determined by high-performance liquid chromatography (HPLC) under the following conditions: a mobile phase of 30% methanol / 70% water and a flow rate of 1.0 mL / min. -1 The detection wavelength is 278nm.

[0014] By adopting the above technical solution, the present invention can achieve the following technical effects: 1. The method for preparing MnCo2O4 catalyst from phosphate-modified precursors of this application achieves uniform doping of phosphate ions within the MnCo2O4 crystal through the synergistic effect of molecular-level modification of the cobalt-manganese hydroxide precursor by phosphate functional groups and subsequent calcination. This fundamentally overcomes the defects of surface modification. The preparation process is simple, with short reaction time, mild conditions, strong controllability, and good reproducibility, making it suitable for high-efficiency water treatment and environmental remediation.

[0015] 2. In this process, by impregnating the cobalt manganese hydroxide precursor with phosphate, the phosphate ions are incorporated into the MnCo2O4 spinel bulk structure during the subsequent calcination process, achieving stable bulk modification rather than simple surface adsorption, thereby significantly improving the thermal stability and structural integrity of the material.

[0016] 3. Furthermore, phosphate ions have a regulatory effect on the coordination environment of metal cations, and can induce the optimization of the valence states of Mn and Co during calcination, thereby increasing the valence state of Mn. 3+ / Mn 4+ Proportion and Co 2+ / Co 3+ The balance of these factors gives the material more highly active sites that can participate in the persulfate activation reaction.

[0017] 4. Furthermore, after the precursor is impregnated with phosphate, excessive particle aggregation can be effectively inhibited, resulting in more uniform MnCo2O4 crystals with a more developed pore structure, which significantly increases the specific surface area of ​​the catalyst and the number of exposed active sites.

[0018] 5. In particular, due to the electronic regulation effect of bulk phosphate, the activity of Co–O and Mn–O bonds in the material is enhanced. During the activation of persulfate or perdisulfate, it can generate active oxygen species such as SO4•– and •OH more efficiently, thereby improving the mineralization efficiency of recalcitrant pollutants such as antibiotics. Furthermore, the conventional hydrothermal, impregnation and calcination process is mild and the steps are clear. The amount of phosphate doping and material properties can be precisely controlled by adjusting the concentration of the impregnation solution and the calcination parameters, making it suitable for industrial scale-up and batch preparation. Attached Figure Description

[0019] Figure 1 This is a flowchart of a method for preparing MnCo2O4 catalyst from a phosphate-modified precursor according to an embodiment of the present invention. Figure 2 In the image, (a) shows the synthesis process of 0.5 PO4-MnCo2O4; (be) shows SEM images of MnCo2O4 and 0.5 PO4-MnCo2O4 at different scales. Figure 3 XRD patterns of different samples; Figure 4 FT-IR spectra of different samples; Figure 5 The oxygen vacancy g-factor ESR spectra of MnCo2O4 and 0.5PO4-MnCo2O4 samples; Figure 6 (ab) Degradation performance of PMS systems activated by different catalysts on SMZ solution and reaction rate constants of different systems; (cd) Degradation performance of PMS systems activated by different concentrations of phosphate-modified catalysts on SMX solution and reaction rate constants of different systems. Figure 7 The effect of (ab) PMS concentration on the performance of 0.5PO4-MnCo2O4-activated PMS and the reaction rate constant of SMZ degradation under different PMS concentrations; (cd) Effect of catalyst dosage on the performance of 0.5 PO4-MnCo2O4 in activating PMS and the reaction rate constant of SMZ degradation under different catalyst dosages; (ef) Effect of pH on the performance of 0.5PO4-MnCo2O4-activated PMS and the reaction rate constant of BPA degradation at different pH values. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. Example 1

[0021] Combination Figure 1 As shown in the figure, this embodiment provides a method for preparing MnCo2O4 catalyst from a phosphate-modified precursor, comprising the following steps: Formulating Co 2+ Mn 2+ A precursor mixture solution; wherein at least one cobalt salt, at least one manganese salt, a fluoride source and a carbon source are dissolved in deionized water and stirred evenly, and the resulting mixture is transferred to a closed hydrothermal reactor for hydrothermal reaction to obtain a cobalt manganese hydroxide precursor; The cobalt manganese hydroxide precursor was immersed and stirred in an aqueous solution containing phosphate source, followed by centrifugation, washing and drying to obtain a phosphate-modified intermediate product. The intermediate product was calcined in an oxygen or air atmosphere to obtain bulk phosphate-modified MnCo2O4 material.

[0022] The synthesis of cobalt manganese hydroxide precursors is specifically as follows: (1) Dissolve 4 mmol Co(NO3)2, 2 mmol Mn(NO3)2, 20 mmol NH4F and 50 mmol CO(NH2)2 in 50 mL of deionized water and stir continuously until a homogeneous mixed solution is formed.

[0023] (2) Transfer the mixed solution to a hydrothermal reactor lined with polytetrafluoroethylene and react at 120°C for 5 hours.

[0024] (3) After the reaction system is naturally cooled to room temperature, the product is collected by centrifugation and washed several times with deionized water and anhydrous ethanol. Finally, it is dried under vacuum at 60-80℃ to obtain the cobalt manganese hydroxide precursor.

[0025] Specifically, regarding phosphate modification: (1) The obtained cobalt manganese hydroxide precursor was immersed in ammonium phosphate (or sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate) aqueous solutions of different concentrations (0.1-0.7M) and stirred vigorously at room temperature for 10 hours to ensure the full adsorption of phosphate ions.

[0026] (2) The mixture was centrifuged and washed repeatedly with deionized water until the supernatant was neutral. The resulting solid was dried at 60-80℃ to obtain a purple phosphate-modified intermediate.

[0027] For the calcination treatment, the specific steps are as follows: the purple intermediate sample is placed in a muffle furnace and heated to 400℃ at a programmed rate of 5℃ / min under air atmosphere, and held at that temperature for 3 h. It is then allowed to cool naturally to room temperature to obtain the bulk phosphate-modified MnCo2O4 catalyst.

[0028] Furthermore, the comparison example and Example 1 will be described in detail below: Comparative Example 1 The preparation method of the MnCo2O4 catalyst in Comparative Example 1 is as follows: S1. Synthesis of cobalt manganese hydroxide precursor: Same as in Example 1.

[0029] S2. Calcination treatment: The cobalt-manganese hydroxide precursor obtained in S1 is placed in a muffle furnace and heated to 400℃ at a programmed rate of 5℃ / min, and held at that temperature for 3 hours. Then it is naturally cooled to room temperature to obtain the MnCo2O4 catalyst.

[0030] Comparative Example 2 The ammonium chloride-modified MnCo2O4 catalyst of Comparative Example 2 is prepared by the following method: S1: Synthesis of cobalt manganese hydroxide precursor: Same as in Example 1.

[0031] S2: Ammonium chloride modification: (1) The obtained cobalt manganese hydroxide precursor was immersed in 0.5M ammonium chloride (NH4Cl) aqueous solution of different concentrations and stirred vigorously at room temperature for 10 h to ensure the full adsorption of phosphate ions.

[0032] (2) The mixture was centrifuged and washed repeatedly with deionized water until the supernatant was neutral. The resulting solid was dried at 60-80℃ to obtain a pink ammonium chloride modified intermediate.

[0033] S3: Calcination treatment: The pink intermediate sample was placed in a muffle furnace and heated to 400°C at a rate of 5°C / min under air atmosphere, and held at that temperature for 3 hours. It was then allowed to cool naturally to room temperature to obtain the bulk ammonium chloride-modified MnCo2O4 catalyst.

[0034] Comparative Example 3 The sodium phosphate-modified MnCo2O4 catalyst of Comparative Example 3 is prepared by the following method: S1: Synthesis of cobalt manganese hydroxide precursor: Same as in Example 1.

[0035] S2: Sodium phosphate modification: (1) The obtained cobalt manganese hydroxide precursor was immersed in 0.5M sodium phosphate (Na3PO4) aqueous solution of different concentrations and stirred vigorously at room temperature for 10h to ensure the full adsorption of phosphate ions.

[0036] (2) The mixture was centrifuged and washed repeatedly with deionized water until the supernatant was neutral. The resulting solid was dried at 60-80℃ to obtain a black phosphate-modified intermediate.

[0037] S3: Calcination treatment: The pink intermediate sample was placed in a muffle furnace and heated to 400℃ at a rate of 5℃ / min under air atmosphere, and held at that temperature for 3 hours. It was then allowed to cool naturally to room temperature to obtain the bulk phosphate-modified MnCo2O4 catalyst.

[0038] Comparative Example 4 The preparation method of the diammonium hydrogen phosphate modified MnCo2O4 catalyst of Comparative Example 4 is as follows: S1: Synthesis of cobalt manganese hydroxide precursor: Same as in Example 1.

[0039] S2: Diammonium hydrogen phosphate modification: (1) The obtained cobalt manganese hydroxide precursor was immersed in 0.5M diammonium hydrogen phosphate ((NH4)3HPO4) aqueous solution of different concentrations and stirred vigorously at room temperature for 10h to ensure the full adsorption of phosphate ions.

[0040] (2) The mixture was centrifuged and washed repeatedly with deionized water until the supernatant was neutral. The resulting solid was dried at 60-80℃ to obtain a black phosphate-modified intermediate.

[0041] S3: Calcination treatment: The pink intermediate sample was placed in a muffle furnace and heated to 400℃ at a rate of 5℃ / min under air atmosphere, and held at that temperature for 3 h. It was then allowed to cool naturally to room temperature to obtain the bulk diammonium hydrogen phosphate-modified MnCo2O4 catalyst.

[0042] Specifically, such as Figure 2The synthesis process of 0.5PO4-MnCo2O4 is shown in (a) and SEM images of MnCo2O4 and 0.5PO4-MnCo2O4 at different scales in (be). The SEM images show that the microstructure of 0.5PO4-MnCo2O4 consists of irregular lamellar structures.

[0043] Figure 3 The XRD patterns of different samples are shown.

[0044] No characteristic diffraction peaks related to Mn and Co nitrides or cobalt-related peaks were observed in the XRD pattern of 0.5 PO4-MnCo2O4. The intensity of the characteristic diffraction peaks decreased linearly with increasing phosphate content, reflecting a significant decrease in the crystallinity of the material.

[0045] Figure 4 The FT-IR spectra of different samples are shown.

[0046] In the infrared spectra of (NH4)2HPO4-MnCo2O4 and (NH4)3PO4-MnCo2O4 samples, the concentrations were 970-1250 cm⁻¹. −1 Distinct characteristic absorption peaks are visible within the range, attributed to the stretching vibration of the PO bond, a prominent characteristic peak of phosphate compounds. Furthermore, in the 759-767 range... cm−1 and 925-934 cm−1 The characteristic bands appearing within the range correspond to the vibrations of the POP group, indicating that some phosphorus species exist in the form of pyrophosphate. The intensity of these peaks increases with increasing phosphate loading, confirming that the phosphate group has been successfully modified on the surface of the MnCo2O4 material. Compared with the Na3PO4-MnCo2O4 sample, the PO vibration peak in (NH4)3PO4-MnCo2O4 shows a low-frequency shift, which can be attributed to the formation of hydrogen bonds or the coordination effect of the metal-phosphate complex. Simultaneously, the introduction of phosphate also affects the metal-oxygen bond vibrations, especially as seen in 644. cm−1 The peak shape changes in the nearby Mn-O bonds. This is mainly because phosphoric acid has a strong electron-withdrawing effect, attracting electrons from oxygen atoms on the MnCo2O4 surface. This electron transfer weakens the interaction between oxygen atoms and surrounding Mn atoms, thus reducing the strength of the Mn-O bonds.

[0047] Figure 5 The oxygen vacancy g-factor ESR spectra of MnCo2O4 and 0.5PO4-MnCo2O4 samples are shown.

[0048] Compared to MnCo2O4, the 0.5PO4-MnCo2O4 sample exhibits a sharper and stronger paramagnetic signal at g = 2.002, indicating that phosphate modification promotes the formation of oxygen vacancies (Ov). Example 2

[0049] Sulfadiazine degradation performance test: The phosphate-modified MnCo2O4 prepared in Example 1 was used to activate persulfate (PMS) for the degradation of SMZ. The specific experimental method is shown below: All catalytic degradation experiments were conducted in continuously stirred 100 mL glass beakers at room temperature. To determine the contributions of adsorption and catalysis to SMZ removal, the catalyst was pre-added to the SMZ solution and stirred for 40 min to reach adsorption-desorption equilibrium. Subsequently, 0.6 mM MPMS was added to initiate the catalytic degradation reaction. Finally, 1.0 mL samples were taken at different time points, filtered through a 0.22 μm filter membrane, and immediately quenched with 10 μL of 2.0 mol / L Na₂S₂O₃ solution. The concentration of the pollutant sulfadiazine was detected using a Hitachi high-performance liquid chromatograph (HPLC). All degradation experiments were performed in triplicate to ensure the reliability of the results. A pseudo-first-order model was used to fit the degradation curves of the target pollutant, and the corresponding apparent rate constants were calculated.

[0050] Among them, the test results are as follows Figure 6 As shown: The adsorption removal rate of SMZ by all catalysts was less than 5% within 10 min, indicating that the adsorption effect was negligible and the degradation mainly originated from catalytic oxidation. Introducing unmodified MnCo2O4 into the PMS system alone resulted in a 33.3% degradation rate of SMZ within 2 min. Various (NH4)3PO4-MnCo2O4 catalysts modified with ammonium phosphate (or sodium tripolyphosphate, sodium hexametaphosphate, or sodium pyrophosphate) significantly improved the activation performance of PMS and the degradation efficiency of SMZ. Among them, 0.5(NH4)3PO4-MnCo2O4 exhibited the best catalytic activity, achieving a 97.2% removal rate of 30 mg / L SMZ within 2 min, with an apparent reaction rate constant k value as high as 1.79 min. -1 The degradation rate was significantly higher than that of the unmodified system. Notably, catalysts modified with different phosphates all exhibited excellent SMZ degradation capabilities. The catalyst modified with (NH4)2HPO4 achieved a degradation rate of 91.4% within 2 minutes and a removal rate of 97.6% within 10 minutes; the catalyst modified with Na3PO4 also achieved a removal rate of 98.6% within 10 minutes. In contrast, the catalyst modified with NH4Cl to introduce amino groups did not significantly improve the SMZ degradation effect compared to unmodified MnCo2O4. In the MnCo2O4 catalyst modified with ammonium phosphate (or sodium tripolyphosphate, sodium hexametaphosphate, sodium pyrophosphate), the phosphate ion (PO4)... 3⁻ () is the key active functional group for improving the activation performance and degradation rate of PMS.

[0051] SMZ degradation experiments under different operating parameters: The optimal catalyst dosage was investigated by varying the initial dosage, with four dosage gradients: 0.05 g / L, 0.1 g / L, 0.2 g / L, and 0.3 g / L. The optimal PMS dosage was also investigated by varying the initial concentration, with five concentration gradients: 0 mM, 0.2 mM, 0.4 mM, 0.6 mM, and 0.8 mM. To study the effect of initial pH, 0.1 M H₂SO₄ and NaOH were used to adjust the pH to 3.0, 5.0, 7.0, 9.0, and 11.0, respectively.

[0052] Among them, the test results are as follows Figure 7 As shown: like Figure 7 As shown in (ab), the degradation rate of SMZ increases with increasing PMS concentration, but when the PMS concentration exceeds 0.6 mM, the degradation rate does not increase significantly. This may be due to the limited number of active sites, which restricts the consumption rate of PMS.

[0053] like Figure 7 As shown in (cd), increasing the catalyst dosage introduces more adsorption and active sites, thereby improving the degradation performance of the 0.5 PO3-MnCo2O4 / PMS system. When the catalyst dosage increased from 0.05 g / L to 0.3 g / L, the SMX removal efficiency increased from 45.6% to 100% within 10 min, and the k value increased from 0.07 min... -1 Increased to 2.03 min -1 .

[0054] The 0.5 PO3-MnCo2O4 / PMS system exhibits excellent reaction kinetics in the pH range of 3-11 and has a wide pH adaptability.

[0055] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a MnCo204 catalyst from a phosphate-modified precursor, characterized in that, Comprising the following steps: S1: preparing a precursor mixed solution containing Co 2+ , Mn 2+ ; wherein at least one cobalt salt, at least one manganese salt, a fluoride source and a carbon source are dissolved in deionized water and stirred uniformly, and then the obtained mixed solution is transferred to a closed hydrothermal reaction kettle for hydrothermal reaction, so as to obtain a cobalt-manganese hydroxide precursor; S2: immersing and stirring the cobalt-manganese hydroxide precursor in an aqueous solution containing a phosphate source, followed by centrifugation, washing and drying to obtain a phosphate-modified intermediate product; S3: calcining the intermediate product under an oxygen or air atmosphere to obtain a bulk-phase phosphate-modified MnCo2O4 material.

2. The method for preparing MnCo2O4 catalyst from phosphate-modified precursor according to claim 1, characterized in that, In step S1, the cobalt salt is cobalt nitrate, the manganese salt is manganese nitrate; the fluoride source is NH4F; and the carbon source is urea.

3. The method for preparing MnCo2O4 catalyst from phosphate-modified precursor according to claim 2, characterized in that, The mixed solution is obtained by dissolving 4 mmol of Co(NO3)2, 2 mmol of Mn(NO3)2, 20 mmol of NH4F and 50 mmol of Co(NH2)2 in 50 mL of deionized water and stirring uniformly.

4. The method for preparing MnCo2O4 catalyst from phosphate-modified precursor according to claim 1, characterized in that, In step S1, the temperature of the hydrothermal reaction is 120℃, and the reaction time is 5h; or it is adjusted within the adjacent range of the temperature and time to achieve equivalent precursor morphology and crystallinity.

5. The method of claim 1, wherein the MnCo204 catalyst is prepared from the phosphate-modified precursor, and the method further comprises the steps of: (a) mixing the phosphate-modified precursor with a Co source to form a mixture; (b) heating the mixture to form a heated mixture; and (c) cooling the heated mixture to form the MnCo204 catalyst. The phosphate source used in step S2 is selected from at least one of (NH4)3PO4, (NaPO3)6, Na6P4O 13 7, Na4P2O7or other soluble phosphate compounds; the molarity n of the initial impregnation solution is 0.1, 0.3, 0.5 or 0.7 M, or in the range 0.05 to 1.0 M; the impregnation time and stirring intensity are determined according to the desired surface / bulk doping degree.

6. The method for preparing MnCo2O4 catalyst from the phosphate-modified precursor according to claim 1, characterized in that, In step S3, the calcination is carried out under an air or near-air atmosphere, the calcination temperature is 400℃, and the calcination time is 3h; or it is carried out within the range of 350-500℃ in temperature and 1-6h in time to obtain the target crystal phase and specific surface area.

7. The method of claim 1, wherein the MnCo204 catalyst is prepared from the phosphate-modified precursor, and the method further comprises the steps of: (a) mixing the phosphate-modified precursor with a Co source to form a mixture; (b) heating the mixture to form a heated mixture; and (c) cooling the heated mixture to form the MnCo204 catalyst. The bulk-phase phosphate-modified MnCo2O4 material is a phosphate-modified spinel-type MnCo2O4, denoted as nPO4-MnCo2O4; wherein n represents that the molar concentration of the phosphate source in the initial immersion solution in step S2 is 0.1, 0.3, 0.5 or 0.7M; the material has detectable phosphate modification or doping in the crystal lattice or interstitial / surface of the crystal lattice, and retains the main spinel structure of MnCo2O4.

8. A bulk phosphate-modified MnCo204catalyst material, characterized in that, The method for preparing a MnCo2O4 catalyst according to any one of claims 1 to 7 is prepared.

9. Use of the bulk phosphato-modified MnCo204 catalyst material according to claim 8 for the activation of persulfate for the degradation of organic pollutants, characterized in that, The catalyst material is used to activate persulfate or permonosulfate oxidants to degrade sulfonamide antibiotics and other target organic pollutants in an aqueous phase.

10. Use of the bulk phosphorate-modified MnCo204 catalyst material according to claim 9 for the activation of persulfate for the degradation of organic pollutants, characterized in that, The residual amount of the sulfonamide compound is determined by high performance liquid chromatography under the following conditions: methanol / water as 30% / 70% as mobile phase, flow rate of 1.0 mL*min -1 , and detection wavelength of 278 nm.

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