Sulfur-modified mesoporous carbon confinement loaded Fe3O4 heterogeneous catalyst as well as preparation method and application thereof

Abstract

The invention discloses a sulfur-modified mesoporous carbon confinement loaded Fe3O4 heterogeneous catalyst as well as a preparation method and application thereof, and belongs to the technical field of sewage treatment. The catalyst comprises: a carbon carrier having a mesoporous channel with a pore size of 3-4 nm, and a sulfur element doped in the carbon carrier; and the active component is Fe3O4 distributed in a mesoporous channel of the carbon carrier. On the basis of a hard template agent with a uniform mesoporous structure, metal salt and organic matter are pyrolyzed under the confinement condition by utilizing the mesoporous characteristic of the hard template agent, the sulfur-modified mesoporous carbon material is obtained, sulfur doping can cause defects of the mesoporous carbon structure to influence electron arrangement of a carbon layer structure, and therefore the sulfur-modified mesoporous carbon material is prepared. The carbon layer structure defect further regulates and controls the content of Fe3O4 oxygen vacancies limited in the carbon layer structure defect through charge transfer between the carbon layer structure defect and Fe3O4, and circulation of iron valence on the surface of iron oxide is effectively promoted, so that the oxidation efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and more specifically, relates to a sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] In recent years, iron-based heterogeneous catalysts have been widely used in the field of advanced oxidation due to their advantages such as wide application range, low price, and no iron sludge generation. In particular, the application of iron oxides such as hematite, goethite, and magnetite in heterogeneous Fenton oxidation has received increasing attention. However, in the actual application process, iron oxide particles are prone to agglomeration, resulting in insufficient exposure of their active sites. At the same time, the slow iron cycle on their surface severely limits the efficient and stable use of the catalyst in the Fenton oxidation process. In addition, traditional iron-based heterogeneous Fenton oxidation mainly generates non-selective free radicals, which are easily interfered by inorganic anions and easily degradable dissolved organic matter when facing multi-pollutant chemical industrial wastewater, resulting in a decrease in the removal efficiency of characteristic pollutants in water. Therefore, developing an iron oxide catalyst with high efficiency, stability, and strong anti-interference ability is of great significance for the application of iron-based heterogeneous catalysts in actual wastewater.

[0003] To improve the surface active sites of iron oxides, iron oxide particles are generally supported on carriers. Common carriers such as graphene oxide and porous carbon materials utilize their large specific surface areas to disperse iron oxides and reduce the agglomeration of iron oxides. However, when the content of iron oxides is relatively high, it is difficult to avoid the agglomeration of dispersed iron oxides, and the problem of low conversion efficiency of Fe(III) to Fe(II) and low surface iron cycle efficiency in the heterogeneous reaction system is difficult to be effectively improved by increasing the dispersion of iron oxides.

[0004] Therefore, it is urgent to study an iron oxide catalyst with a high surface iron cycle efficiency. Summary of the Invention

[0005] 1. Problems to be Solved

[0006] Aiming at the problems of insufficient exposure of metal active sites and low surface iron cycle efficiency of existing iron oxide catalysts in the process of heterogeneous Fenton oxidation, the first aspect of the present invention provides a sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 catalyst;

[0007] The second aspect provides a preparation method of the above sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 catalyst;

[0008] The third aspect provides the above sulfur-modified mesoporous carbon-confined supported Fe3 O 4 Application of catalyst.

[0009] 2. Technical solution

[0010] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0011] In the first aspect of the present invention, there is provided a sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst, comprising:

[0012] A carbon carrier having mesoporous channels with a pore diameter of 3 - 4 nm, and sulfur elements are doped in the carbon carrier;

[0013] Active component: Fe 3 O 4 .

[0014] Calculated according to the ratio of elements, the weight ratio of sulfur element to carbon element is (0.01 - 2.36):(70.25 - 90.45), preferably (0.1 - 0.84):(70.25 - 90.45); the Fe 3 O 4 and the weight ratio of the carbon carrier is (5.25 - 32.75):(70.25 - 90.45).

[0015] The heterogeneous catalyst has an oxygen vacancy concentration of 33.93% - 58.25% in terms of mole fraction.

[0016] When the heterogeneous catalyst is analyzed by Raman spectroscopy, the ratio of carbon defect I D / I G is 2.80 - 3.32.

[0017] According to any embodiment of the first aspect of the object of the present invention, the sulfur element is doped in the carbon carrier in the form of C - S - C bonding.

[0018] According to any embodiment of the first aspect of the object of the present invention, the Fe 3 O 4 is in the form of nanoflower structure and is distributed in the mesoporous channels of the carbon carrier, and the particle size of the Fe 3 O 4 is 100 - 150 nm.

[0019] In the second aspect of the present invention, there is provided a preparation method of the above sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst, comprising the following steps:

[0020] S1. Ingredients: Dissolve the raw materials containing a carbon source, a sulfur source, and an iron source in a dispersion medium to obtain a precursor solution;

[0021] S2. Vacuum induction: Mix the precursor solution obtained in step S1 with a templating agent evenly under vacuum conditions and dry it;

[0022] S3. Pyrolysis: Calcinate the material obtained in step S2 under the protection of an inert gas;

[0023] S4. Remove the templating agent to obtain a mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst.

[0024] According to any embodiment of the second aspect of the object of the present invention, in step S1, the carbon source can be selected from substances with two or more phenolic hydroxyl groups. By using the reduction reaction between the phenolic hydroxyl group and ferric iron, ferrous iron is formed, enabling the substances to be connected by iron-oxygen bonds. Preferably, it is phenolphthalein;

[0025] The sulfur source is preferably sodium poly(styrenesulfonate). During the pyrolysis process of the polymer, the sulfonic acid group is released more slowly, ensuring more uniform doping of sulfur atoms in the carbon layer;

[0026] The iron source is preferably ferric chloride. In addition, ferric nitrate and ferric sulfate can also be used to provide the iron source.

[0027] According to any embodiment of the second aspect of the object of the present invention, in step S1, the weight ratio of the carbon source, the sulfur source, and the iron source is (10 - 100):(1 - 200):(5 - 30).

[0028] According to any embodiment of the second aspect of the object of the present invention, in step S1, the dispersion medium is a mixed solution of deionized water and ethanol. The volume ratio of the deionized water and ethanol can be any ratio for dissolving the raw materials, such as (0 - 10):(0 - 10); preferably (1 - 5):(5 - 10), more preferably (1 - 3):(5 - 7). More preferably, the volume ratio of deionized water and ethanol is 1:6.

[0029] According to any embodiment of the second aspect of the object of the present invention, in step S2, the templating agent is a templating agent with a uniform mesoporous structure. Preferably, it is a hard templating agent, such as SiO with a uniform mesoporous structure 2 or Al 2 O 3 , and the addition amount of the templating agent satisfies the following mass ratio: the weight ratio of the carbon source, the sulfur source, the iron source, and the templating agent is (10 - 100):(1 - 200):(5 - 30):(200:800).

[0030] According to any embodiment of the second aspect of the object of the present invention, in step S2, the precursor solution obtained in step S1 is mixed with a template agent under vacuum conditions and shaken well. After the mixture is ultrasonically vibrated for 10 - 30 min, it is dried at 30 - 80 °C for 10 - 15 h. By mixing the precursor solution with the template agent under vacuum conditions, the precursor solution enters the mesoporous channels of the template agent.

[0031] According to any embodiment of the second aspect of the object of the present invention, in step S3, the inert gas is argon. In addition, other inert gases such as nitrogen and helium can also be used as protective gases.

[0032] According to any embodiment of the second aspect of the object of the present invention, in step S3, the calcination temperature is 600 - 1000 °C, preferably 650 °C - 950 °C, the calcination holding time is 2 - 5 h, and the heating rate is 2 - 5 °C / min.

[0033] According to any embodiment of the second aspect of the object of the present invention, in step S4, to remove the template agent, the material prepared in step S3 is subjected to alkali etching with an alkaline solution. Preferably, when using SiO 2 as a hard template agent, the material prepared in step S3 is dispersed in a sodium hydroxide solution with a concentration of 1 - 5 mol / L, stirred at 50 - 80 °C in a water bath for 5 - 20 h, and then the mixture is rinsed with deionized water until the pH = 7, and then dried at 30 - 80 °C.

[0034] According to any embodiment of the second aspect of the object of the present invention, in step S4, when using Al 2 O 3 as a hard template agent, the removal method thereof refers to the removal method of SiO 2 .

[0035] In the third aspect of the present invention, there is provided an application of a sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst for treating electron-rich pollutants in the first aspect of the present invention.

[0036] According to any embodiment of the third aspect of the object of the present invention, the electron-rich pollutants are sulfonamide organic compounds and phenolic organic compounds.

[0037] The sulfonamides can be sulfamethoxazole, or other sulfonamide pollutants such as sulfadiazine, sulfisoxazole, sulfamethizole, sulfasalazine, etc.

[0038] The phenols can be phenol, or other electron-rich phenolic pollutants such as chlorophenol, bromophenol, and bisphenol A.

[0039] This catalyst is particularly suitable for the treatment of electron-rich pollutants in organic wastewater systems with complex compositions.

[0040] Optionally, in a possible implementation manner of the third aspect, the dosage of the initial catalyst is 0.1 - 1 g / L, and the dosage of persulfate is 0.06 - 1 g / L.

[0041] This method prepares a catalyst by using mesoporous silica as a template, and simultaneously regulates the content of oxygen vacancies in Fe 3 O 4 nano-flowers through the mesoporous confinement effect and in-situ sulfur doping, forming a mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst. On the one hand, the sulfur-modified mesoporous carbon can promote the exposure of its surface active sites by dispersing Fe 3 O 4 , effectively solving the problem of mutual coverage of active sites. At the same time, the oxygen vacancies formed by the mesoporous confinement can effectively promote the valence cycle of iron, enabling the transfer of electrons among the catalyst, oxidant, and pollutants. On the other hand, the S doping on the mesoporous carbon will cause structural defects in the mesoporous carbon, affecting the electron arrangement of the carbon layer structure. The structural defects of the carbon layer further regulate the content of oxygen vacancies confined in Fe 3 O 4 through charge transfer between Fe 3 O 4 and enhance the surface activity of the catalyst. Through the synergistic effect of sulfur modification and oxygen vacancies, pollutants are degraded through a non-radical path of direct electron transfer during the activation process of persulfate, without being interfered by ions and dissolved organic matter in water, thereby improving the anti-environmental interference ability of the catalyst.

[0042] 3. Beneficial effects

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] Firstly, the sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst provided by the present invention:

[0045] (1) Fe 3 O 4 is loaded on the sulfur-modified mesoporous carbon material, and the confinement environment of the mesoporous carbon can promote the generation of low-valent iron and oxygen vacancies; sulfur doping will cause structural defects in the mesoporous carbon, affecting the electron arrangement of the carbon layer structure. The structural defects of the carbon layer further regulate the content of Fe 3 O 4 oxygen vacancies through charge transfer between Fe 3 O 4 and effectively promote the valence cycle of iron on the surface of iron oxides, thereby promoting the oxidation efficiency;

[0046] (2) Fe 3 O 4 Form a nanoflower structure in the mesoporous channels of the carbon support to prevent Fe 3 O 4 from agglomerating. Fe 3 O 4 is evenly distributed in the mesoporous channels of the carbon material, exposing more active sites;

[0047] Second, the preparation method of the sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst:

[0048] (1) Based on a hard template agent with mesoporous channels, use its mesoporous characteristics to pyrolyze metal salts and organic substances under confined conditions to obtain a sulfur-modified mesoporous carbon material. The confined environment can promote the generation of low-valent iron and oxygen vacancies; sulfur doping will cause structural defects in the mesoporous carbon, and the carbon defects further regulate the oxygen vacancy content of Fe 3 O 4 confined therein through charge transfer between Fe 3 O 4 , effectively promoting the cycle of iron valence states on the surface of iron oxides, thereby promoting the oxidation efficiency;

[0049] (2) Co-regulate the oxygen vacancies of Fe 3 O 4 through the calcination temperature and sulfur doping, effectively promoting the cycle of iron valence states on the surface of iron oxides, thereby promoting the oxidation efficiency;

[0050] Third, the application of the sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst:

[0051] (1) Apply the prepared catalyst to the degradation of electron-rich pollutants by persulfate. Utilize the synergistic catalytic effect of sulfur modification and oxygen vacancies to effectively regulate the direct electron transfer process of oxygen vacancies, thereby effectively ensuring the overall activity and long-term stable use of the catalyst;

[0052] (2) Apply the prepared catalyst to the degradation of water pollutants by persulfate, especially for multi-pollutant chemical industrial wastewater. Degrade pollutants through a non-radical pathway that mediates the direct electron transfer reaction of persulfate to pollutants, without being interfered by other pollutants and ions, effectively improving the degradation efficiency of target pollutants under the interference of various organic substances and anions;

[0053] (3) Utilize the mesoporous confined space formed inside the catalyst to effectively enrich pollutants, thereby ensuring efficient electron transfer. Description of the Drawings

[0054] The technical solution of the present invention will be further described in detail below in conjunction with the drawings and embodiments. However, it should be noted that these drawings are only designed for explanatory purposes and thus do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0055] Figure 1 TEM characterization images of Fe 3 O 4 @SMC prepared in Example 1, (a) 200 nm, (b) 100 nm;

[0056] Figure 2 TEM characterization images of Fe 3 O 4 @SMC prepared in Example 1, EDS characterization images, where (a) green is C element, (b) red is Fe element, (c) purple is O element, (d) yellow is S element;

[0057] Figure 3 XRD spectra of Fe 3 O 4 @SMC prepared in Example 1, Fe 3 O 4 @SC prepared in Comparative Example 1, Fe 3 O 4 @MC prepared in Comparative Example 2, SMC prepared in Comparative Example 3, and Fe 3 O 4 prepared in Comparative Example 4;

[0058] Figure 4 BET adsorption curves of Fe 3 O 4 @SMC prepared in Example 1, Fe 3 O 4 @SC prepared in Comparative Example 1, Fe 3 O 4 @MC prepared in Comparative Example 2, SMC prepared in Comparative Example 3, and Fe 3 O 4 prepared in Comparative Example 4;

[0059] Figure 5 BET adsorption curves of Fe 3 O 4 @SMC prepared in Example 1, Fe 3 O 4 @SC prepared in Comparative Example 1, Fe 3 O 4 @MC prepared in Comparative Example 2, and Fe 3 O4 EPR spectra;

[0060] Figure 6 XPS spectra (a) and Raman spectra (b) of sulfur source catalysts with different contents in Examples 1 - 5, where I D / I G is for D - peak and G - peak intensity ratio. The D - peak represents lattice defects. The larger the I D / I G值 , the more defects in the C atom crystal; O surf is surface oxygen, O ads is adsorbed oxygen, O latt is lattice oxygen;

[0061] Figure 7 XPS spectra (a) and Raman spectra (b) of catalysts with different calcination temperatures in Example 1, Comparative Example 5, and Examples 6 - 8;

[0062] Figure 8 Degradation effects of Fe 3 O 4 @SMC prepared in Example 1 on different pollutants in organic wastewater. Among them, SMX is sulfamethoxazole, NB is nitrobenzene, BA is benzoic acid, and ATZ is atrazine;

[0063] Figure 9 Degradation effects of Fe 3 O 4 @SMC doped with different sulfur contents in Examples 1 - 5 on sulfamethoxazole;

[0064] Figure 10 Degradation effects of adding different quenchers on sulfamethoxazole. Among them, FFA is tert - butanol, TBA is furfuryl alcohol, MeOH is methanol, and K 2 Cr 2 O 7 is potassium dichromate;

[0065] Figure 11 Degradation effects of Fe 3 O 4 @SMC prepared in Example 1, Fe 3 O 4 @SC prepared in Comparative Example 1, Fe 3 O 4 @MC prepared in Comparative Example 2, and SMC prepared in Comparative Example 3 on sulfamethoxazole;

[0066] Figure 12 Fe 3 O4 Degradation effect of @SMC on sulfamethoxazole;

[0067] Figure 13 For Fe prepared in Example 1 3 O 4 Circulation effect of @SMC on sulfamethoxazole;

[0068] Figure 14 For Fe prepared in Example 1 at different pH values 3 O 4 Degradation effect of @SMC on sulfamethoxazole;

[0069] Figure 15 For Fe prepared in Example 1 under different ion interferences 3 O 4 Degradation effect of @SMC on sulfamethoxazole. Detailed implementation manners

[0070] The present disclosure can be more easily understood by referring to the following description in combination with the accompanying drawings and examples, all of which form a part of the present disclosure. It should be understood that the present disclosure is not limited to the specific products, methods, conditions or parameters described and / or illustrated herein. Further, the terms used herein are for the purpose of describing specific embodiments by way of example only and are not intended to be limiting, unless otherwise specified.

[0071] It should also be understood that, for the sake of clarity, certain features of the present disclosure may be described herein in the context of separate embodiments, but may also be provided in combination with each other in a single embodiment. That is, unless clearly incompatible or specifically excluded, each separate embodiment is considered combinable with any other embodiment, and such combination is considered to represent another different embodiment. Conversely, for the sake of brevity, the various features of the present disclosure described in the context of a single embodiment may also be provided separately or in any sub-combination. Finally, although a particular embodiment may be described as part of a series of steps or part of a more general structure, each step or sub-structure itself may also be considered an independent embodiment.

[0072] Unless otherwise specified, it should be understood that each individual element in a list and each combination of the individual elements in the list will be construed as a different embodiment. For example, when describing items by using conjunctive terms such as "…… and / or ……", the description should be understood to include any one of the associated listed items and all combinations of one or more of them.

[0073] Generally, the use of the term "about" indicates an approximation that can vary according to the desired characteristics obtained from the disclosed subject matter and will be interpreted in a context-dependent manner based on functionality. Thus, one of ordinary skill in the art will be able to interpret a certain degree of variance on a case-by-case basis. In some cases, the number of significant digits used in expressing a particular value can be a representative technique for determining the variance permitted by the term "about". In other cases, the gradient in a series of values can be used to determine the range of variance permitted by the term "about". Further, all ranges in this disclosure are inclusive and combinable, and references to values stated in a range include each value within that range.

[0074] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terms and / or include any and all combinations of one or more of the related listed items.

[0075] In the present invention, materials, unless otherwise specified, can all be obtained by market purchase, i.e., commercially available products.

[0076] 【1】A preparation method of a sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst

[0077] The preparation method includes the following steps:

[0078] S1. Ingredients preparation: Dissolve raw materials including a carbon source, a sulfur source, and an iron source in a dispersion medium to obtain a precursor solution.

[0079] S2. Vacuum induction: Mix the precursor solution obtained in step S1 with a template agent evenly under vacuum conditions and dry.

[0080] S3. Pyrolysis: Calcinate the material obtained in step S2 under the protection of an inert gas.

[0081] S4. Remove the template agent to obtain a mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst.

[0082] In step S1, the carbon source can be selected from substances with two or more phenolic hydroxyl groups. Through the reduction reaction between the phenolic hydroxyl group and trivalent iron, divalent iron is formed, enabling the substances to be connected by iron-oxygen bonds. Preferably, it is phenolphthalein.

[0083] The sulfur source is preferably sodium poly(styrene sulfonate). During the pyrolysis process, the sulfonic acid groups are released more slowly, which can ensure that sulfur atoms are doped more evenly in the carbon layer.

[0084] The iron source is preferably ferric chloride. In addition, ferric nitrate and ferric sulfate can also be used to provide the iron source.

[0085] The weight ratio of the carbon source, sulfur source and iron source is (10 - 100):(1 - 200):(5 - 30).

[0086] The dispersion medium is a mixed solution of deionized water and ethanol. Other dispersion media that can dissolve the carbon source, sulfur source and iron source are also applicable. The volume ratio of deionized water to ethanol can be any ratio for dissolving the raw materials. Among them, deionized water is beneficial to the dissolution of inorganic salts, and ethanol is beneficial to the dissolution of organic salts. In actual selection, it can be further selected according to the type of raw materials. For example, the volume ratio of deionized water to ethanol is (0 - 10):(0 - 10); preferably (1 - 5):(5 - 10), more preferably (1 - 3):(5 - 7), and more preferably still, the volume ratio of deionized water to ethanol is 1:6. Preferably, the volume ratio of deionized water to ethanol is 1:6. Preferably, 0.1 - 1 g of phenolphthalein, 0.01 - 0.2 g of sodium polystyrene sulfonate, and 0.05 - 0.3 g of ferric chloride hexahydrate are dissolved in the mixed solution of deionized water and ethanol to prepare the precursor solution.

[0087] Among them, the sulfur doping amount affects the content of Fe 3 O 4 oxygen vacancies, and further affects the cycle of iron valence states on the surface of iron oxides. Generally speaking, the sulfur doping amount is positively correlated with Fe 3 O 4 oxygen vacancies. When the sulfur doping amount increases, the degree of carbon defects doped with sulfur increases, resulting in an increase in the content of oxygen vacancies; conversely, when the sulfur doping amount decreases, the content of oxygen vacancies decreases. Preferably, the weight of sulfur doping amount and Fe 3 O 4 is (0.01 - 2.36):(5.25 - 32.75), and more preferably (0.1 - 0.84):(5.25 - 32.75).

[0088] In step S2, the template agent is a template agent with a uniform mesoporous structure, preferably a hard template agent, such as SiO with a uniform mesoporous structure 2 or Al 2 O 3, the carbon support prepared using a hard template agent with a uniform mesoporous structure also has uniformly distributed mesoporous channels. The confined space provided by the mesoporous channels is conducive to the generation of more low-valent iron and oxygen vacancies. Under confined conditions, the growth of magnetite crystals is affected by the spatial confinement of the carbon structure, hindering the epitaxial growth of the crystals and causing the original lattice mismatch, which in turn leads to the generation of more oxygen vacancies in the magnetite epitaxial layer. The formation of oxygen vacancies regulates the iron electronic structure coordinated with it to generate more low-valent iron, thus facilitating the generation of more low-valent iron and oxygen vacancies. In addition, the confined space of the mesoporous channels can disperse magnetite to form nanoflowers and prevent agglomeration.

[0089] Mix the precursor solution obtained in step S1 with the template agent under vacuum conditions and shake well. After ultrasonically vibrating the mixture for 10 - 30 min, dry it at 30 - 80 °C for 10 - 15 h.

[0090] The addition amount of the template agent satisfies the mass ratio: the weight ratio of the carbon source, sulfur source, iron source, and SiO 2 is (10 - 100):(1 - 200):(5 - 30):(200:800).

[0091] In step S3, the inert gas is argon. In addition, other inert gases such as nitrogen and helium can also be used as protective gases.

[0092] The calcination temperature is 600 - 1000 °C, the calcination holding time is 2 - 5 h, and the heating rate is 2 - 5 °C / min.

[0093] As described above, the calcination temperature affects the content of Fe 3 O 4 oxygen vacancies. As the calcination temperature increases, the degree of sulfur-doped carbon defects first increases and then decreases, resulting in the content of oxygen vacancies first increasing and then decreasing.

[0094] The co-regulation of the content of Fe 3 O 4 oxygen vacancies is achieved through the calcination temperature and sulfur doping. The principle is that the calcination temperature and S doping cause defects in the mesoporous carbon structure, affecting the electronic arrangement of the carbon layer structure. The carbon layer structure defects further regulate the content of Fe 3 O 4 confined therein through charge transfer with Fe 3 O 4 oxygen vacancy content.

[0095] In step S4, remove the template agent. When using SiO 2When used as a hard template agent, disperse the material obtained in step S3 in a sodium hydroxide solution with a concentration of 1-5 mol / L, stir it for 5-20 h under the condition of a water bath at 50-80 °C, then rinse the mixture with deionized water until the pH = 7, and then dry it at 30-80 °C.

[0096] When using Al 2 O 3 as a hard template agent, the removal method can refer to the removal method of SiO 2 .

[0097] 【2】A sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst

[0098] Its structure includes:

[0099] A carbon carrier having mesoporous channels with a pore diameter of 3-4 nm, and sulfur elements are doped in the carbon carrier;

[0100] Active component: Fe 3 O 4 .

[0101] Calculated according to the proportion of elements, the weight ratio of sulfur element to carbon element is (0.1-0.84):(70.25-90.45); the weight ratio of the Fe 3 O 4 to the carbon carrier is (5.25-32.75):(70.25:90.45).

[0102] The sulfur element is doped in the carbon carrier by C-S-C bonding.

[0103] The Fe 3 O 4 is in the form of a nanoflower structure and is distributed in the mesoporous channels of the carbon carrier. The particle size of the Fe 3 O 4 is 100-150 nm.

[0104] Among them, Fe 3 O 4 grows into a nanoflower structure in the mesoporous channels of the carbon carrier, which is beneficial to the dispersion of Fe 3 O 4 , avoids particle aggregation, and at the same time exposes more oxygen vacancies, promotes the cycle of iron valence states on the surface of iron oxide, and thus promotes the oxidation efficiency.

[0105] 【3】Application of a sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst

[0106] The sulfur-modified mesoporous carbon was confined to load Fe 3 O 4 Heterogeneous catalysts are used to treat electron-rich pollutants, especially electron-rich pollutants in organic wastewater with complex components.

[0107] The electron-rich pollutants are sulfonamide organic matter and phenol organic matter.

[0108] The sulfonamide may be sulfamethoxazole, or may be sulfadiazine, sulfisoxazole, sulfadimethoxazole, sulfasalazine and other sulfonamide pollutants.

[0109] The phenols may be phenol, or may be electron-rich phenol pollutants such as chlorophenol, bromophenol and bisphenol A.

[0110] The complex organic wastewater also contains electron-deficient pollutants, such as nitrobenzene, benzoic acid, and atrazine, which often appear in the organic wastewater as interferences when treating the organic wastewater.

[0111] The catalyst of the present application has a good catalytic effect on pollutants, especially electron-rich pollutants such as sulfamethoxazole, wherein the electron-rich pollutants are low ionization potential pollutants, which are the minimum energy required for an atom or molecule to lose an electron during ionization. The lower the ionization potential, the easier it is to donate electrons, so the direct electron transfer process is stronger. Conversely, it is an ionization potential pollutant, that is, an electron-deficient pollutant.

[0112] The organic wastewater to be treated used in the examples of the present application is the production wastewater of a chemical plant. The concentrations of nitrobenzene, benzoic acid, and atrazine are 50-80 mg / L, the concentration of sulfamethoxazole is 5-10 mg / L, the pH of the wastewater is 5-8, and the main pollutants are organic substances such as sulfamethoxazole, nitrobenzene, benzoic acid, and atrazine.

[0113] The initial catalyst dosage is 0.1-1 g / L, and the persulfate dosage is 0.06-1 g / L.

[0114] Example 1

[0115] A method for preparing sulfur-modified mesoporous carbon-confined Fe 3 O 4 The method of heterogeneous catalyst comprises the following steps:

[0116] S1. Ingredients: 0.5 g of phenolphthalein, 0.2 g of sodium poly(p-styrene sulfonate) (Aladdin, CAS: 25704-18-1, average molecular weight of about 70,000), and 0.1 g of ferric chloride hexahydrate are dissolved in a mixed solution of deionized water and ethanol to prepare a precursor solution;

[0117] S2. Vacuum Induction: The precursor solution obtained in step S1 is mixed and shaken well with 0.5 g of mesoporous SiO 2 under vacuum conditions. After the mixture is ultrasonically vibrated for 20 min, it is dried at 70 °C for 12 h;

[0118] S3. Pyrolysis: The material obtained in step S2 is placed in a tubular furnace filled with argon, and the temperature is raised to 850 °C at a rate of 5 °C / min and held for 4 h;

[0119] S4. Removal of Template Agent: The material obtained in step S2 is dispersed in a 2 mol / L sodium hydroxide solution and stirred in a water bath at 70 °C for 10 h. Then, the mixture is rinsed with deionized water until the pH is neutral, and then dried at 70 °C to obtain a mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst, denoted as Fe 3 O 4 @SMC.

[0120] The characterization of the mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst prepared in Example 1 is as Figures 1-5 shown. As Figure 1 Fe 3 O 4 @SMC's TEM photo shows that the prepared Fe 3 O 4 @SMC uses sulfur-modified mesoporous carbon as the carrier, and Fe 3 O 4 nanoflowers are loaded on the mesoporous carbon, and the Fe 3 O 4 cluster size is 100 - 150 nm.

[0121] Figure 2 The EDS results show that in the prepared Fe 3 O 4 @SMC, each element is evenly dispersed, indicating that sulfur and Fe 3 O 4 are evenly dispersed on the mesoporous carbon. According to the EDS surface scan results, the weight ratio of sulfur element to carbon element is 0.84:87.99; the weight ratio of the said Fe 3 O 4 to the carbon carrier is 11.17:87.99.

[0122] Figure 3 The XRD results show that in the prepared Fe 3 O 4 @SMC, iron is loaded on the sulfur-modified mesoporous carbon in the form of Fe 3 O 4 crystals.

[0123] Figure 4 BET results show that in SiO 2 Under hard template conditions, the mesoporous carbon structure was formed by utilizing its mesoporous properties, sulfur doping and Fe 3 O 4 After loading, the catalyst still maintains a certain mesoporous structure.

[0124] Figure 5 EPR results show that sulfur doping can increase the oxygen vacancy density of the catalyst.

[0125] Comparative Example 1

[0126] The other conditions of the Fenton-like catalyst prepared in Comparative Example 1 were the same as those in Example 1, except that no hard template agent, mesoporous SiO 2 , the steps are:

[0127] 0.5 g of phenolphthalein, 0.2 g of sodium poly(p-styrene sulfonate) and 0.1 g of ferric chloride hexahydrate were dissolved in a mixed solution of deionized water and ethanol. After sufficient stirring, the precursor solution was directly dried at 70 ° C for 2 h and then pyrolyzed. The other conditions were the same as those in Example 1. The obtained catalyst was sulfur-modified carbon-supported Fe without mesoporous channels. 3 O 4 Heterogeneous catalyst, named Fe 3 O 4 @SC.

[0128] Comparative Example 2

[0129] The other conditions of the Fenton-like catalyst prepared in Comparative Example 2 are the same as those in Example 1, except that no sulfur source sodium poly(p-styrene sulfonate) is added, and the steps are as follows:

[0130] 0.5 g of phenolphthalein and 0.1 g of ferric chloride hexahydrate were dissolved in a mixed solution of deionized water and ethanol to prepare a precursor solution. The other conditions were the same as those in Example 1. The prepared catalyst was a mesoporous carbon-confined Fe catalyst without sulfur doping. 3 O 4 Heterogeneous catalyst, named Fe 3 O 4 @MC.

[0131] Comparative Example 3

[0132] The catalyst prepared in Comparative Example 3 is consistent with that in Example 1, except that no iron source ferric chloride hexahydrate is added, and the steps are as follows:

[0133] Dissolve 0.5 g of phenolphthalein and 0.2 g of sodium polystyrene sulfonate in a mixed solution of deionized water and ethanol to prepare a precursor solution. Other conditions are the same as those in Example 1. The prepared catalyst is a sulfur-modified mesoporous carbon heterogeneous catalyst, named SMC.

[0134] Comparative Example 4

[0135] The Fe prepared in Comparative Example 4 3 O 4 The catalyst is the same as that in Example 1, except that: the sulfur source sodium polystyrene sulfonate and the hard template agent mesoporous SiO 2 are not added. The steps are as follows:

[0136] Dissolve 0.1 g of ferric chloride hexahydrate in a mixed solution of deionized water and ethanol to prepare a precursor solution. Other conditions are the same as those in Example 1. The prepared catalyst is Fe 3 O 4 catalyst, named Fe 3 O 4 .

[0137] Example 2

[0138] The method of this example is basically the same as that of Example 1, except that the sulfur content is different. The addition amount of sodium polystyrene sulfonate is 25 mg, that is, in step S1, 0.5 g of phenolphthalein, 0.025 g of sodium polystyrene sulfonate, and 0.1 g of ferric chloride hexahydrate are dissolved in a mixed solution of deionized water and ethanol to prepare a precursor solution.

[0139] Example 3

[0140] The method of this example is basically the same as that of Example 1, except that the sulfur content is different. The addition amount of sodium polystyrene sulfonate is 50 mg, that is, in step S1, 0.5 g of phenolphthalein, 0.05 g of sodium polystyrene sulfonate, and 0.1 g of ferric chloride hexahydrate are dissolved in a mixed solution of deionized water and ethanol to prepare a precursor solution.

[0141] Example 4

[0142] The method of this example is basically the same as that of Example 1, except that the sulfur content is different. The addition amount of sodium polystyrene sulfonate is 75 mg, that is, in step S1, 0.5 g of phenolphthalein, 0.075 g of sodium polystyrene sulfonate, and 0.1 g of ferric chloride hexahydrate are dissolved in a mixed solution of deionized water and ethanol to prepare a precursor solution.

[0143] Example 5

[0144] The method of this embodiment is basically the same as that of Embodiment 1, except that the sulfur content is different, and the addition amount of sodium polystyrene sulfonate is 100 mg. That is, in step S1, 0.5 g of phenolphthalein, 0.1 g of sodium polystyrene sulfonate, and 0.1 g of ferric chloride hexahydrate are dissolved in a mixed solution of deionized water and ethanol to prepare a precursor solution.

[0145] Figure 6 (a) The XPS results show that with the increase of the content of sodium polystyrene sulfonate, the oxygen vacancy concentration gradually increases. The oxygen vacancy concentration is calculated according to the ratio of adsorbed oxygen O ads and total oxygen, where the total oxygen is the sum of surface oxygen O surf , adsorbed oxygen O ads and lattice oxygen O latt . With the increase of the content of sodium polystyrene sulfonate, the oxygen vacancy concentration increases from 33.93% to 58.25%, indicating that sulfur doping can effectively increase the oxygen vacancy density of the catalyst.

[0146] Figure 6 (b) The Raman results show that with the increase of the content of sodium polystyrene sulfonate, the I D / I G of the catalyst gradually increases, and the range of I D / I G increases from 2.80 to 3.32, indicating that the degree of carbon defect increases, and thus the oxygen vacancy content increases.

[0147] Comparative Example 5

[0148] The method of this comparative example is basically the same as that of Embodiment 1, except that the calcination temperature is different. The calcination temperature is 550 °C, that is, the material obtained in step S2 is placed in a tubular furnace filled with argon and calcined at 550 °C at a heating rate of 5 °C / min for 4 h.

[0149] Embodiment 6

[0150] The method of this embodiment is basically the same as that of Embodiment 1, except that the calcination temperature is different. The calcination temperature is 650 °C, that is, the material obtained in step S2 is placed in a tubular furnace filled with argon and calcined at 650 °C at a heating rate of 5 °C / min for 4 h.

[0151] Embodiment 7

[0152] The method of this embodiment is basically the same as that of Embodiment 1, except that the calcination temperature is different. The calcination temperature is 750 °C, that is, the material obtained in step S2 is placed in a tubular furnace filled with argon and calcined at 750 °C at a heating rate of 5 °C / min for 4 h.

[0153] Embodiment 8

[0154] The method of this embodiment is basically the same as that of Embodiment 1, except that the calcination temperature is different. The calcination temperature is 950 °C, that is, the material obtained in step S2 is placed in a tubular furnace filled with argon and calcined at 950 °C for 4 h at a heating rate of 5 °C / min.

[0155] Figure 7 (a) XPS results show that as the calcination temperature increases from 550 °C to 950 °C, the oxygen vacancy concentration first increases and then decreases; Figure 7 (b) Raman results show that as the temperature increases, I D / I G first increases and then decreases, indicating that as the calcination temperature increases, the carbon defects first increase and then decrease. Carbon defects are generally vacancy defects formed by the absence or deviation of carbon atoms from their normal positions, and further indicating that the oxygen vacancy content first increases and then decreases.

[0156] Embodiment 9

[0157] Application of the sulfur-modified mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst prepared in Embodiment 1.

[0158] In this embodiment, the organic wastewater to be treated is the production wastewater of a chemical plant, and the pollutants include sulfamethoxazole, nitrobenzene, benzoic acid, and atrazine. The concentrations of nitrobenzene, benzoic acid, and atrazine are 50 mg / L respectively, and the concentration of sulfamethoxazole is 5 mg / L. The pH of the wastewater is 7.6.

[0159] The dosage of Fe 3 O 4 @SMC prepared in Embodiment 1 is 0.1 g / L, the dosage of persulfate is 5 mmol / L, and the total treatment time of the oxidation system is 15 min.

[0160] The removal rate change of sulfonamide compounds in the wastewater is as Figure 8 shown. The results show that with the addition of persulfate, sulfamethoxazole undergoes a rapid reaction stage and degrades 80% within 7 min and 95% within 15 min. This is because when using mesoporous SiO 2 as a template to prepare the catalyst, the formation of sulfur-modified mesoporous carbon is induced by the mesoporous confinement effect. The dispersion effect of sulfur-modified mesoporous carbon on Fe 3 O 4 nano-flowers can promote the exposure of surface active sites of Fe 3 O 4 ; oxygen vacancies can promote the cycling of iron valence states; S doping will cause structural defects in mesoporous carbon and affect the electronic arrangement of the carbon layer structure. The carbon layer structure defects interact with Fe 3 O4 Intermediate charge transfer further regulates the Fe 3 O 4 oxygen vacancy content confined therein, improving the anti-interference ability of the catalyst. Through the synergistic effect of sulfur modification and oxygen vacancies, pollutants are degraded through a non-radical pathway of direct electron transfer during the induced activation process of persulfate. The mesoporous confined space formed by the catalyst is conducive to the effective enrichment of pollutants, improving the degradation efficiency of pollutants. In addition, Figure 8 it can be seen that within 15 minutes, the removal rates of nitrobenzene, benzoic acid, and atrazine are 12%, 17%, and 9% respectively, indicating that the catalyst of the present invention has an obvious selective degradation effect on characteristic pollutants when treating organic wastewater with complex components.

[0161] The catalysts doped with different sulfur contents obtained in Examples 1-5 were used for the treatment of organic wastewater, and the change in the removal rate of sulfamethoxazole was as Figure 9 shown. Figure 9 Among them, as the doping amount of sulfur element increases, the degree of defect of the mesoporous carbon structure increases accordingly, which further promotes the formation of oxygen vacancies and low-valent iron, and further improves the catalytic effect.

[0162] Example 10

[0163] In this example, the catalyst prepared in Example 1 was used for the radical quenching experiment. 0.05 mM furfuryl alcohol (FFA), 500 mM tert-butanol (TAB), 500 mM methanol (MeOH), and 5 mM potassium dichromate (K 2 Cr 2 O 7 ) were respectively added to the reaction system to study the reaction mechanism of the mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst.

[0164] Among them, potassium dichromate is used to inhibit the direct electron transfer process, furfuryl alcohol is commonly used to quench singlet oxygen, tert-butanol is used to quench hydroxyl radicals, methanol is used to quench sulfate radicals and hydroxyl radicals, and the removal rate of sulfamethoxazole in the wastewater is as Figure 10 , and the results show that after adding potassium dichromate, only 5% of sulfamethoxazole was removed in 15 minutes, significantly inhibiting the degradation of sulfamethoxazole, indicating that the degradation of organic matter is mainly carried out through the direct electron transfer process. After adding furfuryl alcohol, the concentration of sulfamethoxazole in the organic wastewater was removed by 96%, indicating that a small amount of singlet oxygen would be generated. After adding tert-butanol and methanol, the degradation rate of sulfamethoxazole was about 99% in both cases, indicating that the yields of hydroxyl radicals and sulfate radicals are relatively low, thus proving that the mesoporous carbon-confined supported Fe 3 O 4Heterogeneous catalysts mainly degrade pollutants through non-radical pathways via direct electron transfer.

[0165] Comparative Example 6

[0166] The catalyst obtained in Comparative Examples 1-4 was used to treat organic wastewater. The organic wastewater to be treated in this comparative example was consistent with that in Example 9. The removal rate of sulfamethoxazole changed as follows: Figure 11 The results show that in the absence of mesoporous SiO 2 When used as a template, the degradation rate of sulfamethoxazole by the catalyst was 70%, which was due to the presence of SiO 2 The mesoporous properties of the metal salts and organic matter can be pyrolyzed under confined conditions, and further prepared by alkaline etching to form sulfur-modified mesoporous carbon can ensure that Fe 3 O 4 Nanoflowers are evenly dispersed on carbon materials, and the mesoporous confinement effect can induce sulfur modification and Fe 3 O 4 The formation of oxygen vacancies on the upper surface promotes the direct electron transfer process. In the absence of sulfur doping, the degradation rate of sulfamethoxazole by the catalyst is only 52%. This is attributed to the fact that sulfur doping causes mesoporous carbon structural defects that affect the electronic arrangement of the carbon layer structure. The carbon layer structural defects are formed by interacting with Fe 3 O 4 The intercalated charge transport further regulates the Fe 3 O 4 The oxygen vacancy content enhances the surface activity of the catalyst. In the absence of oxygen vacancies, the degradation rate of sulfamethoxazole is only 49%, which is because the oxygen vacancies formed by mesoporous confinement can effectively promote the valence cycle of iron. The synergistic effect of sulfur modification and oxygen vacancies degrades pollutants through a non-radical pathway of direct electron transfer during the persulfate activation process.

[0167] Comparative Example 7

[0168] The catalysts obtained by different calcination temperatures obtained in Examples 6-8 and Comparative Example 5 were used to treat organic wastewater. The organic wastewater to be treated in this comparative example was consistent with that in Example 9. The removal rate of sulfamethoxazole changed as follows: Figure 12 As shown in the figure, with the increase of calcination temperature, the degradation efficiency of SMX first increases and then decreases. This may be because increasing the temperature will increase the defect degree of mesoporous carbon, thereby increasing the content of oxygen vacancies and low-valent iron, thereby improving the catalytic effect. However, too high a temperature will cause the collapse of the mesoporous carbon structure, affect the oxygen vacancy content, and thus cause the loss of catalyst active sites.

[0169] Embodiment 11

[0170] The sulfur-modified mesoporous carbon prepared in Example 1 was used to confine Fe 3 O 4 Heterogeneous catalyst Fe3 O 4 @SMC studied the stability of the catalyst. Five consecutive degradations of SMX were carried out under the same conditions as in Example 9, and the experimental results are as Figure 13 shown. The results show that the removal rate of sulfamethoxazole decreased slightly after five cycles, and the removal rates after each cycle were 95%, 91%, 88%, 84%, and 80% respectively, indicating that the catalyst has high cycle stability and can be used for long-term use. In addition, after the fifth cycle, the catalyst was calcined at 850 °C under argon flow for 4 h, and the catalytic effect of the catalyst could reach the initial level, further proving the stability of the catalyst prepared by the present invention.

[0171] Example 12

[0172] The other conditions of this example were the same as those of Example 9, except that the pH of the wastewater was adjusted to 2, 3, 4, 5, 6, 7, 8, 9, and 10, and the Fe 3 O 4 @SMC prepared in Example 1, Fe 3 O 4 @SC prepared in Comparative Example 1, Fe 3 O 4 @MC prepared in Comparative Example 2, and SMC prepared in Comparative Example 3 were used for control degradation experiments.

[0173] The ability of the catalyst to treat organic wastewater under different pH conditions is as Figure 14 shown. Compared with Fe 3 O 4 @SC, Fe 3 O 4 @MC, and SMC, Fe 3 O 4 @SMC had a degradation efficiency of sulfamethoxazole higher than 92% in a wide pH range, indicating that the catalyst had a stable catalytic effect. The possible reason was that the higher oxygen vacancies increased the content of low-valent iron, enhanced the direct electron transfer effect, and thus the catalyst had a good catalytic effect in a wide pH range.

[0174] Example 13

[0175] The other conditions of this example were the same as those of Example 9, except that 50 mM of SO 4 2- 、NO 3 - 、Cl - 、HCO 3 - ions were added to the sulfamethoxazole wastewater for the degradation experiment of sulfamethoxazole to study the anti-ion interference ability of the catalyst.

[0176] The ability of the catalyst to degrade sulfamethoxazole under different anion interference conditions is as Figure 15 shown. The influence of SO 4 2- , NO 3 - , Cl - , CO 3 2- , PO 4 3- , and HA on the degradation efficiency of sulfamethoxazole can be basically ignored, indicating that the mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst provided by the present invention has good anti-ion interference ability. This is because the mesoporous carbon-confined supported Fe 3 O 4 heterogeneous catalyst degrades sulfamethoxazole mainly through the non-free radical pathway of electron transfer reaction, improving the anti-environmental interference ability of the catalyst.

[0177] The above description is only a preferred embodiment of the present application and an explanation of the applied technical principles. Those skilled in the art should understand that the scope involved in the present application is not limited to the technical solution formed by the specific combination of the above technical features. At the same time, it should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the (but not limited to) technical features with similar functions disclosed in the present application.

[0178] Except for the technical features described in the specification, the remaining technical features are well-known to those skilled in the art. To highlight the innovative features of the present invention, the remaining technical features are not described in detail here.

Claims

1. A sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst, characterized in that: include: A carbon support having mesoporous channels with a pore size of 3-4 nm; Sulfur element is doped in the carbon support and forms a bond with the carbon support via CSC; Active component: Fe3O4 distributed in the mesoporous channels of the carbon support; Wherein, the weight ratio of sulfur element to carbon element is (0.01-2.36): (70.25-90.45); The heterogeneous catalyst has an oxygen vacancy concentration of 33.93% to 58.25% by mole fraction.

2. The sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst according to claim 1, characterized in that: The weight ratio of Fe3O4 to carbon carrier is (5.25-32.75):(70.25-90.45).

3. The sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst according to claim 2, characterized in that: When the heterogeneous catalyst is analyzed by Raman spectroscopy, the carbon defect I D / I G The ratio is 2.80~3.

32.

4. The sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst according to claim 1, characterized in that: The Fe3O4 is in a nanoflower structure and is distributed in the mesoporous channels of the carbon carrier. The particle size of the Fe3O4 nanoflower is 100-150nm.

5. A method for preparing a sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst, characterized in that: Including the following raw materials: Carbon source, sulfur source and iron source; The following steps are involved: S1. Ingredients: dissolving raw materials including a carbon source, a sulfur source and an iron source in a dispersion medium to prepare a precursor solution; S2, vacuum induction: mixing the precursor solution obtained in step S1 with the template under vacuum conditions, and drying; S3, pyrolysis: calcining the material obtained in step S2 under the protection of an inert gas; S4. Remove the template to obtain a sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst.

6. The preparation method according to claim 5, characterized in that: In step S1, the weight ratio of the carbon source, the sulfur source and the iron source is (10-100): (1-200): (5-30).

7. The preparation method according to claim 5, characterized in that: In step S2, the template is a hard template having a uniform mesoporous structure; The added amount of the template agent satisfies the following weight ratio of the carbon source, the sulfur source, the iron source and the template agent: (10-100): (1-200): (5-30): (200:800).

8. The preparation method according to claim 5, characterized in that: In step S3, the calcination temperature is 600-1000°C, the calcination holding time is 2-5h, and the heating rate is 2-5°C / min.

9. The preparation method according to claim 7, characterized in that: In step S4, the material obtained in step S3 is alkali-etched using an alkaline solution.

10. A use of the sulfur-modified mesoporous carbon-confined Fe3O4 heterogeneous catalyst as claimed in any one of claims 1 to 4, or the heterogeneous catalyst prepared by the preparation method as claimed in any one of claims 5 to 9, characterized in that: Catalysts for persulfate degradation of electron-rich pollutants.

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