Biomass carbon loaded manganese dioxide catalyst as well as preparation method and application thereof

Abstract

The invention discloses a biomass carbon loaded manganese dioxide catalyst as well as a preparation method and application thereof. The biomass carbon loaded manganese dioxide catalyst comprises a carrier and MnO2 loaded on the surface of the carrier, and the carrier is carbonized biomass obtained by performing alkali treatment and hydrogen peroxide treatment on biomass and then carbonizing the biomass in an inert atmosphere. The supported catalyst prepared by the method has proper valence and morphology, a MnO2 mixed phase appears, more oxygen vacancies are generated, generation of free radicals in the activation process of peroxymonosulfate (PMS) is facilitated, PMS can be effectively activated to remove organic pollutants, and the activation efficiency of MnO2 on PMS and the operation stability of MnO2 in a packed column are greatly improved. Compared with a traditional method for adjusting the oxygen vacancy of MnO2, the method for loading the biochar is relatively controllable, simple in mode and low in cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of persulfate advanced oxidation, in particular to a carbonized biomass such as carbonized loofah sponge loaded manganese dioxide prepared in situ and its application in the field of activating persulfate to degrade pollutants. BACKGROUND

[0002] With the development of industry and agriculture, the pollution of persistent organic pollutants in the environment is gradually increasing, which seriously affects human health and the ecological environment [1] . In recent years, persulfate-based advanced oxidation technology has received extensive attention, and the active species (SO4 •- 、 • OH、 1 O2) generated by persulfate-based advanced oxidation technology can oxidize organic pollutants into small molecular carbon sources. The activation of persulfate can be achieved by homogeneous activation (metal ions), energy activation (ultrasound, light, heat) and heterogeneous catalyst activation [2] . Among them, homogeneous activation is not easy to recover metal ions, energy activation has low efficiency and high energy consumption, while heterogeneous catalyst activation has the advantages of easy recovery, high efficiency and low energy consumption. Common heterogeneous catalysts include carbon materials and metal oxides [3] . Among them, carbon materials are complex to prepare and have low stability, while metal oxides are easy to synthesize and have good stability [4, 5] . Among oxides, manganese oxides have stable structure, low cost, easy synthesis and low toxicity, and are widely used in the activation of persulfate [6] . Factors that determine the activation ability of manganese oxides include crystal type, metal element valence, oxygen vacancy, etc. In the past research, the ways to regulate these factors include changing the sintering temperature and atmosphere, doping, etc [7] . These methods are relatively complex and have low controllability. It is of great significance to design a simple and controllable method to adjust the structure of manganese oxide catalyst to improve its activation of persulfate.

[0003] REFERENCES [1] HU P, LONG M. Cobalt-catalyzed sulfate radical-based advanced oxidation: A review on heterogeneous catalysts and applications [J]. Applied Catalysis B: Environmental, 2016, 181: 103-17. [2] GHANBARI F, MORADI M. Application of peroxymonosulfate and itsactivation methods for degradation of environmental organic pollutants:Review [J]. Chemical Engineering Journal, 2017, 310: 41-62. [3] LI J, YANG L, LAI B, et al. Recent progress on heterogeneous Fe-based materials induced persulfate activation for organics removal [J].Chemical Engineering Journal, 2021, 414: 128674. [4] KOHANTORABI M, MOUSSAVI G, GIANNAKIS S. A review of theinnovations in metal- and carbon-based catalysts explored for heterogeneousperoxymonosulfate (PMS) activation, with focus on radical vs. non-radicaldegradation pathways of organic contaminants [J]. Chemical EngineeringJournal, 2021, 411: 127957. [5] ZHENG X, NIU X, ZHANG D, et al. Metal-based catalysts forpersulfate and peroxymonosulfate activation in heterogeneous ways: A review[J]. Chemical Engineering Journal, 2022, 429: 132323. [6] HUANG J, ZHANG H. Mn-based catalysts for sulfate radical-basedadvanced oxidation processes: A review [J]. Environment International, 2019,133: 105141. Summary of the Invention

[0004] Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for preparing biomass carbon-regulated defective manganese dioxide (biomass carbon-supported manganese dioxide catalyst) and its application, addressing the shortcomings of the prior art.

[0005] To solve the above-mentioned technical problems, the present invention discloses the following technical solution: In a first aspect, the present invention discloses a biomass carbon-supported manganese dioxide catalyst.

[0006] The biomass carbon-supported manganese dioxide catalyst includes a support and MnO2 supported on the surface of the support.

[0007] The carrier is obtained by treating biomass with alkali and hydrogen peroxide, followed by carbonization in an inert atmosphere to obtain carbonized biomass; wherein the biomass includes peanut shells, corn stalks, soybean stalks, loofah sponges, etc., preferably loofah sponges, to obtain carbonized loofah sponges; wherein in the alkali treatment, the alkali is a sodium hydroxide solution with a mass concentration of 3-10%, such as 4%, 6%, or 8%; the alkali treatment temperature is 80-120℃, such as 100℃; and the alkali treatment time is 3-15 hours, such as 8 hours, 10 hours, or 12 hours. In the hydrogen peroxide treatment, the mass concentration of H2O2 is 5-15%, such as 8%, 10%, or 12%; the temperature of the hydrogen peroxide treatment is 60-100℃, such as 80℃; and the treatment time is 3-15 hours, such as 8 hours, 10 hours, or 12 hours. The inert atmosphere is argon, nitrogen, or helium; the carbonization temperature in the inert atmosphere is 600-1000℃, such as 700℃, 800℃, or 900℃; the time is 1-5 hours, such as 3 hours; and the rate of heating to 600-1000℃ is 2-5℃ / min.

[0008] The MnO2 is in the form of nanoparticles.

[0009] The manganese dioxide in the biomass carbon-supported manganese dioxide catalyst has a mixed phase of a and g crystals.

[0010] In a second aspect, the present invention discloses a method for preparing the biomass carbon-supported manganese dioxide catalyst described in the first aspect above.

[0011] The method involves first removing hemicellulose and lignin from air-dried biomass through chemical cleaning, then performing high-temperature carbonization under an inert atmosphere to obtain biomass carbon, and finally adding the biochar to the MnO2 synthesis system to obtain a carbonized biomass-supported MnO2 catalyst; specifically, it includes the following steps: (1) Biomass is treated with alkali, washed with water, treated with hydrogen peroxide, washed and dried with water, and then carbonized in an inert atmosphere to obtain carbonized biomass. (2) The obtained carbonized biomass was placed in KMnO4 solution, and Mn(CH3COO)2 solution was added. The mixture was stirred to generate MnO2 precursor supported on the carbonized biomass. (3) The obtained precursor is heated and kept warm to obtain a biomass carbon-supported manganese dioxide catalyst.

[0012] In step (1), the alkali in the alkali treatment is a sodium hydroxide solution with a mass concentration of 3-10%, such as 4%, 6%, or 8%, the temperature of the alkali treatment is 80-120℃, such as 100℃, and the time of the alkali treatment is 3-15h, such as 8h, 10h, or 12h.

[0013] In step (1), the mass concentration of H2O2 in the hydrogen peroxide treatment is 5-15%, such as 8%, 10%, or 12%, the temperature of the hydrogen peroxide treatment is 60-100℃, such as 80℃, and the time of the hydrogen peroxide treatment is 3-15h, such as 8h, 10h, or 12h.

[0014] In step (1), the inert atmosphere is argon, nitrogen or helium, the carbonization temperature in the inert atmosphere is 600-1000℃, such as 700℃, 800℃ or 900℃, the time is 1-5h, such as 3h; the rate of heating to 600-1000℃ is 2-5℃ / min.

[0015] In step (2), the concentration of the KMnO4 solution is 0.01-0.05 mol / L, such as 0.02 mol / L; the concentration of the Mn(CH3COO)2 solution is 0.05-0.25 mol / L, such as 0.1 mol / L; the mass-volume ratio of the carbonized biomass to the KMnO4 solution and the Mn(CH3COO)2 solution is 0.05-0.3 g: 50-150 mL: 30-75 mL, such as 0.1 g: 50-150 mL: 30-75 mL.

[0016] In step (3), the heating and heat preservation is carried out at 100-200℃ for 2-5 hours; the rate of heating to 100-200℃ is 2-5℃ / min.

[0017] Thirdly, the present invention discloses the application of the catalyst described in the first aspect or the catalyst prepared by the method described in the second aspect in the catalytic removal of organic pollutants by persulfate.

[0018] The organic pollutants include 4-chlorophenol (4-CP), sulfamethoxazole (SMX), 2,4-dichlorophenol (2,4-DCP), p-hydroxybenzoic acid (p-HBA), and 4-chloroaniline (4-CA).

[0019] The supported catalyst prepared in this invention possesses suitable valence states and morphology, exhibiting a mixed phase of MnO2 and generating more oxygen vacancies. This is beneficial for the generation of free radicals during the persulfate (PMS) activation process, effectively activating PMS to remove organic pollutants and significantly improving the activation efficiency of MnO2 for PMS and its stability in packed columns. Compared to traditional methods of adjusting MnO2 oxygen vacancies, the biochar-supported method is relatively controllable, simple, and low-cost.

[0020] The technical solution provided by this invention solves the problems of complex processes and low controllability in the existing methods of regulating the structure of manganese oxides. This invention provides a simple solution for regulating parameters such as the crystal phase, valence state of metal elements, and oxygen vacancies of manganese oxides.

[0021] Beneficial effects: The carbonized loofah sponge-supported manganese dioxide MnO2@LC and MnO2@2LC provided by this invention exhibit excellent performance in removing organic pollutants from activated persulfate (PMS), with superior performance and stability compared to the comparative sample MnO2. The MnO2@LC provided by this invention demonstrates superior performance in removing organic pollutants from activated persulfate (PMS) compared to the comparative samples MnO2@LC-untreated, MnO2@peanut, MnO2@corn, and MnO2@soybean. This invention is significant for developing new methods to regulate oxide catalysts and improve the activation efficiency of PMS. Furthermore, the materials designed in this invention utilize biochar, providing an important reference for the application of biochar in catalyst synthesis and regulation. The preparation methods of carbonized loofah sponge-supported manganese dioxide MnO2@LC and MnO2@2LC are simple, exhibit excellent performance, and have the potential for large-scale use, making them highly significant for research and application. Attached Figure Description

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0023] Figure 1These are the X-ray diffraction (XRD) patterns of MnO2@LC, MnO2@2LC, MnO2@peanut, MnO2@soybean, and MnO2@untreated as described in this invention, as well as the standard cards for α-phase MnO2 and γ-phase MnO2.

[0024] Figure 2 These are scanning electron microscope (SEM) images of MnO2@LC, MnO2@2LC, and MnO2 included in this invention.

[0025] Figure 3 These are the electron paramagnetic resonance (ESR) spectra of MnO2@LC and MnO2 contained in this invention.

[0026] Figure 4 This refers to the X-ray photoelectron spectra of MnO2@LC and MnO2 with Mn 3s contained in this invention.

[0027] Figure 5 This is a comparison chart of the performance of MnO2@LC, MnO2@2LC, MnO2@LC-untreated, MnO2@peanut, MnO2@corn, MnO2@soybean and MnO2-activated persulfate (PMS) in degrading 4-chlorophenol (4-CP).

[0028] Figure 6 This is a comparison chart of the performance of MnO2@LC and MnO2-activated PMS in degrading sulfamethoxazole (SMX), 2,4-dichlorophenol (2,4-DCP), p-hydroxybenzoic acid (p-HBA), and 4-chloroaniline (4-CA) contained in this invention.

[0029] Figure 7 This is the continuous wastewater treatment device using a packed column used in this invention.

[0030] Figure 8 This is a stability graph showing the performance of MnO2@2LC and MnO2 activated persulfate (PMS) in the degradation of 4-chlorophenol (4-CP) contained in this invention.

[0031] Figure 9 This is a stability graph of the performance of activated persulfate (PMS) degradation of 4-chlorophenol (4-CP) by MnO2@LC contained in this invention. Detailed Implementation

[0032] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0033] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0034] Developing highly efficient heterogeneous catalysts is crucial for improving the removal of recalcitrant organic pollutants by activated persulfate (PMS). Manganese oxides are commonly used as catalysts for PMS activation due to their low cost, low toxicity, and high activation efficiency. Current research indicates that parameters such as the crystal form, manganese valence state, and oxygen vacancies of manganese oxides significantly affect their PMS activation efficiency. Therefore, controlling these parameters of manganese oxides is an important pathway to improve their activation ability. Currently, common methods include changing the sintering temperature and atmosphere, and adding doping elements. These methods increase costs and complicate processes. The carbonized loofah sponge-supported manganese dioxide MnO2@LC and MnO2@2LC provided in this invention exhibit superior PMS activation performance and stability compared to unsupported synthesized MnO2. The MnO2@LC catalyst provided by this invention exhibits superior PMS activation performance compared to the comparative samples MnO2@LC-untreated (loofah sponge without NaOH and H2O2 treatment), MnO2@peanut (peanut shell as carbon source), MnO2@corn (corn stalk as carbon source), and MnO2@soybean (soybean stalk as carbon source). The method for regulating the properties of manganese oxides proposed in this invention can also serve as a reference for preparing more advanced novel catalysts.

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0036] Example 1: In-situ growth of MnO2 on the surface of carbonized loofah sponge (1) Cut the air-dried loofah sponge into small pieces. Then place the cut pieces in an ethanol solution and clean them several times under ultrasonic conditions. After cleaning, put the material into an 80 ℃ oven to dry for 12 h.

[0037] Place the washed and dried loofah sponge in an eggplant-shaped flask, add a 6% NaOH solution to cover the loofah sponge, and reflux at 100 °C for 10 h.

[0038] Pour out the cooled liquid after reflux, add pure water, wash the loofah sponge 5-6 times, add a 10% H2O2 solution to cover the loofah sponge, and reflux at 80 ℃ for 10 h.

[0039] Pour out the cooled liquid after reflux, add pure water, wash the loofah sponge 5-6 times, and dry it.

[0040] (2) Place the dried loofah sponge in a tube furnace and heat it at 5 °C for 5 min, starting from room temperature, under an argon atmosphere. -1The temperature was increased to 800 °C and treated for 3 hours. Before the heat treatment, argon gas was passed through the tube for 30 minutes to ensure that the tube was in an inert gas state. The treated loofah sponge was then ground to obtain carbonized loofah sponge LC.

[0041] (3) Weigh 0.3 g KMnO4 and dissolve it in 100 mL of water to make its concentration 0.019 M.

[0042] Weigh 1.2 g of Mn(CH3COO)2•4H2O and dissolve it in 50 mL of water to make its concentration 0.098 M.

[0043] Weigh 0.1 g LC and add it to 100 mL of KMnO4 solution. After stirring thoroughly, disperse by sonication for 30 min. Then, add 50 mL of Mn(CH3COO)2 solution dropwise. The entire process is carried out with stirring at a constant temperature of 25 °C. After the Mn(CH3COO)2 solution has been added, continue stirring for 30 min to obtain a suspension.

[0044] The obtained suspension was washed several times by centrifugation with ethanol and water to obtain the MnO2@LC precursor.

[0045] (4) The obtained MnO2@LC precursor was placed in a muffle furnace and treated at 200 °C for 3 h with a heating rate of 5 °C / min. -1 MnO2@LC was obtained by loading carbonized fibrous sponge.

[0046] Example 2 Synthesis of MnO2@2LC The amount of LC in Example 1 was changed from 0.1 g to 0.2 g, and the rest of the operation was the same as in Example 1, to obtain MnO2@2LC.

[0047] Synthesis of MnO2 in the control group sample of Comparative Example 1 Under the condition that LC does not participate in the synthesis process, the remaining operations are the same as in Example 1, and MnO2 is obtained as control group-1.

[0048] Comparative Example 2: Synthesis of control sample MnO2@LC-untreated Without treating the loofah sponge with NaOH and H2O2, the remaining operations were the same as in Example 1, and MnO2@LC-untreated was obtained as the control group-2.

[0049] Comparative Example 3: Synthesis of MnO2@peanut from control sample Replace the loofah sponge with peanut shells, and follow the same procedure as in Example 1 to obtain MnO2@peanut as the control group-3.

[0050] Comparative Example 4: Synthesis of MnO2@maize from control sample Replace the loofah sponge with corn stalks, and follow the same procedures as in Example 1 to obtain MnO2@corn as the control group-4.

[0051] Comparative Example 5: Synthesis of MnO2@soybean from control sample Replace the loofah sponge with soybean straw, and follow the same procedure as in Example 1 to obtain MnO2@soybeans as the control group-5.

[0052] The catalysts MnO2@LC, MnO2@2LC, and MnO2 from Examples 1, 2, and 1 (Comparative Example 1) were characterized, and their performance in catalytically activating PMS to degrade pollutants was compared and their stability was tested. The performance and partial structural characterization of the catalysts MnO2@LC-untreated, MnO2@peanut, MnO2@corn, and MnO2@soybean from Comparative Example 2, 3, 4, and 5 in catalytically activating PMS to degrade pollutants were also included in the comparison. Specific experimental data are as follows.

[0053] 1. Characterization Test (1) According to Figure 1 The powder XRD diffraction patterns of the catalyst show that the diffraction peaks of MnO2 match well with the standard card of α-phase manganese dioxide, while the manganese dioxide in MnO2@LC, MnO2@2LC, MnO2@LC-untreated, MnO2@peanut, MnO2@corn, and MnO2@soybean has a mixed phase of α and γ. This preliminarily indicates that the in-situ generation method using carbonized loofah sponge alters the crystal form of manganese dioxide.

[0054] (2) such as Figure 2 As shown, characterization of the catalyst by scanning electron microscopy (SEM) revealed that MnO2 (control group-1) was granular, while MnO2@LC and MnO2@2LC exhibited a morphology of particles attached to carbon, indicating that manganese dioxide in MnO2@LC and MnO2@2LC was successfully loaded onto carbonized loofah sponge.

[0055] (3) such as Figure 3 As shown, electron paramagnetic resonance (ESR) spectra revealed that MnO2@LC exhibited a stronger signal compared to MnO2 (control group-1), indicating that MnO2@LC contains more oxygen vacancies.

[0056] (4) such as Figure 4 As shown, the Mn 3s spectrum obtained by X-ray photoelectron spectroscopy (XPS) revealed that MnO2@LC exhibits a larger distance between the double peaks, indicating that the Mn valence state in MnO2@LC is lower.

[0057] 2. Test for catalytic activation of PMS to degrade 4-chlorophenol (4-CP) (1) Comparison of activation capabilities of catalysts During the test, the solution was water, the concentration of PMS was 0.16 mM, the concentration of 4-CP was 10 ppm, and the catalyst concentration was 0.2 g L / L. -1 The reaction temperature was 25 °C and the reaction time was 1 h.

[0058] Figure 5 The curves and pseudo-first-order reaction kinetics fits for the degradation of 4-CP by MnO2@LC, MnO2@2LC, MnO2@LC-untreated, MnO2@peanut, MnO2@corn, MnO2@soybean, and MnO2-catalyzed activated PMS are presented. The first-order reaction kinetics fits of the degradation curves show that the kinetic constants of MnO2@LC and MnO2@2LC are 7.6 times and 1.7 times that of MnO2, respectively. This indicates that the performance of manganese dioxide is significantly improved after in-situ loading with carbonized loofah sponge. Furthermore, the kinetic constant of MnO2@LC is 2.3 times that of MnO2@LC-untreated, indicating that the treatment of loofah sponge with NaOH and H2O2 solutions is beneficial to improving the final performance of the material. In comparison with catalysts synthesized using other biochar, the kinetic constants of MnO2@LC are 3.5, 2.8, and 3.0 times that of MnO2@peanut, MnO2@corn, and MnO2@soybean, respectively. This indicates that loofah sponge is more effective as a carbon source in improving catalyst performance.

[0059] Figure 6 This study compares the performance of MnO2@LC and MnO2 in degrading sulfamethoxazole (SMX), 2,4-dichlorophenol (2,4-DCP), p-hydroxybenzoic acid (p-HBA), and 4-chloroaniline (4-CA). For all four pollutants, MnO2@LC outperformed MnO2, demonstrating that the improved pollutant degradation performance of MnO2 after in-situ loading with carbonized loofah sponge has a certain degree of universality.

[0060] (2) Stability assessment and comparison of catalysts To more accurately assess the practical value of the catalysts, MnO2, MnO2@2LC, and MnO2@LC were respectively filled into substrates such as... Figure 7 In the packed column shown, 0.16 mM PMS was mixed with 10 mg L... -1 The 4-CP mixed solution was subjected to a certain rate (10.4 mL / h). -1 The solution (0.4 g catalyst + 4 g quartz sand) was passed through a packed column and reacted with the catalyst. The solution after a certain reaction time was taken and the concentration of 4-CP was tested.

[0061] Figure 8 andFigure 9 The results are shown in the continuous packed column experiments for MnO2, MnO2@2LC, and MnO2@LC, respectively. It can be seen that after 16 h, the degradation efficiency of 4-CP by MnO2 decreased to approximately 70%. For MnO2@LC, the degradation efficiency of 4-CP remained above 99% for the first 108 h, only gradually decreasing to 83% after 384 h. Furthermore, for MnO2@2LC, the degradation efficiency of 4-CP remained above 95% for the first 7 h, only gradually decreasing to 84% after 16 h. This indicates that MnO2@LC exhibits significantly higher stability.

[0062] In summary, the MnO2@LC and MnO2@2LC synthesized in this patent exhibit stronger activation ability and higher stability compared to the MnO2 control group, demonstrating good application potential. The MnO2@LC synthesized in this patent also shows superior performance compared to the MnO2@LC-untreated, MnO2@peanut, MnO2@corn, and MnO2@soybean control groups. Furthermore, the MnO2@LC synthesized in this patent possesses a complex phase, more oxygen vacancies, and a lower valence state compared to the MnO2 control group. The method for regulating metal oxides provided in this patent is simple, controllable, practical, and instructive.

[0063] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A biomass carbon-supported manganese dioxide catalyst, characterized in that, It includes a carrier and MnO2 loaded on the surface of the carrier. The carrier is carbonized biomass obtained by treating biomass with alkali and hydrogen peroxide, and then carbonizing it in an inert atmosphere.

2. The biomass carbon-supported manganese dioxide catalyst according to claim 1, characterized in that, The carbonized biomass is carbonized loofah sponge.

3. The biomass carbon-supported manganese dioxide catalyst according to claim 1, characterized in that, The MnO2 is in the form of nanoparticles.

4. The method for preparing the biomass carbon-supported manganese dioxide catalyst according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Biomass is treated with alkali and hydrogen peroxide, and then carbonized in an inert atmosphere to obtain carbonized biomass; (2) The obtained carbonized biomass was placed in KMnO4 solution, and Mn(CH3COO)2 solution was added. The mixture was stirred to generate MnO2 precursor supported on the carbonized biomass. (3) The obtained precursor is heated and kept warm to obtain a biomass carbon-supported manganese dioxide catalyst.

5. The catalyst according to claim 1 or the preparation method according to claim 4, characterized in that, In the alkali treatment, the alkali is a sodium hydroxide solution with a mass concentration of 3-10%, the alkali treatment temperature is 80-120℃, and the alkali treatment time is 3-15h.

6. The catalyst according to claim 3 or the preparation method according to claim 4, characterized in that, In the hydrogen peroxide treatment, the mass concentration of H2O2 is 5-15%, the temperature of the hydrogen peroxide treatment is 60-100℃, and the treatment time is 3-15h.

7. The catalyst according to claim 3 or the preparation method according to claim 4, characterized in that, The inert atmosphere is argon, nitrogen, or helium, and the carbonization temperature in the inert atmosphere is 600-1000℃, and the time is 1-5 hours.

8. The preparation method according to claim 4, characterized in that, In step (2), the concentration of the KMnO4 solution is 0.01-0.05 mol / L; the concentration of the Mn(CH3COO)2 solution is 0.05-0.25 mol / L; and the mass-to-volume ratio of the carbonized biomass to the KMnO4 solution and the Mn(CH3COO)2 solution is 0.05-0.3 g: 50-150 mL: 30-75 mL.

9. The preparation method according to claim 4, characterized in that, In step (3), the heating and heat preservation is carried out at 100-200℃ for 2-5 hours; the rate of heating to 100-200℃ is 2-5℃ / min.

10. The use of the catalyst according to any one of claims 1-3 in the catalytic removal of organic pollutants by catalyzing persulfate.

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