Magnetic ZIF derived carbon composite material as well as preparation method and application thereof

Abstract

The invention discloses a magnetic ZIF derived carbon composite material as well as a preparation method and application thereof, and belongs to the technical field of catalytic materials. The preparation method comprises the following steps: mixing an iron source, a zinc source and 2-methylimidazole in a solvent, so that the molar ratio of the iron element to the zinc element to the 2-methylimidazole is (1-2): (0-1): (10-14) to obtain a mixture; standing and aging the mixture for 48-72 hours, and filtering a solid product to obtain a precursor; and placing the precursor in an inert atmosphere, and heating at 900-1100 DEG C for 2-3 hours to obtain the magnetic ZIF derived carbon composite material. The obtained magnetic ZIF derived carbon composite material has a porous carbon skeleton, and the porous carbon skeleton is uniformly loaded with an iron-based active component; the iron-based active component comprises zero-valent iron and ferroferric oxide, can be used for catalytic degradation of tetracycline, and can realize rapid separation under an external magnetic field.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, specifically relating to a magnetic ZIF-derived carbon composite material, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Tetracycline (TC), a widely used antibiotic, is difficult to degrade effectively in the natural environment, and its residues pose a potential threat to ecosystem balance and public health. Among existing pollution control technologies, advanced oxidation processes (AOPs) have been proven to be one of the effective means of degrading organic pollutants, with the Fenton reaction attracting widespread attention due to its strong oxidizing power. However, traditional homogeneous Fenton technology still has significant drawbacks in practical applications, including the need for the reaction system to operate under strongly acidic conditions (typically pH 2-4), the generation of large amounts of iron-containing sludge during the reaction, and the difficulty in recovering and reusing iron-based catalysts, which limit its further promotion and application.

[0004] To overcome the shortcomings of homogeneous systems, heterogeneous Fenton technology has emerged, employing solid catalysts to achieve a wider pH range, reduce sludge production, and improve catalyst recyclability. Metal-organic frameworks (MOFs) are considered ideal catalyst support precursors due to their tunable structure and high specific surface area. ZIF-8, a typical zeolite-type imidazolium ester framework, can be transformed into a porous carbon material with abundant pores after high-temperature pyrolysis, effectively loading and stabilizing metal active sites. However, in existing preparation methods, directly combining iron species with the ZIF-8 precursor followed by pyrolysis often results in poor iron dispersion within the carbon framework, leading to aggregation and sintering during heat treatment. This results in uneven distribution of active sites and reduced accessibility, thus affecting the final catalyst's degradation efficiency and long-term operational stability. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a magnetic ZIF-derived carbon composite material, its preparation method, and its application. Using ZIF-8 as a precursor, it is prepared by introducing an iron source and then pyrolyzing at high temperature. The composite material exhibits high catalytic activity, easy magnetic separation and recovery, and good cycle stability.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing a magnetic ZIF-derived carbon composite material, comprising the following steps: S1. Mix the iron source, zinc source and 2-methylimidazole in a solvent so that the molar ratio of iron, zinc and 2-methylimidazole is (1~2):(0~1):(10~14) to obtain a mixture; S2. Allow the mixture to stand and age for 48-72 hours, filter the solid product, and obtain the precursor. S3. Place the precursor in an inert atmosphere and heat it at 900~1100℃ for 2~3 hours to obtain the magnetic ZIF-derived carbon composite material.

[0007] Secondly, the magnetic ZIF-derived carbon composite material prepared by the above-mentioned method is a magnetic ZIF-derived carbon composite material.

[0008] Thirdly, the application of the aforementioned magnetic ZIF-derived carbon composite material in the degradation of tetracycline in wastewater.

[0009] The beneficial effects of this invention are as follows: This invention provides a magnetic ZIF-derived carbon composite material and its preparation method, ensuring Fe³⁺ + The highly dispersed and uniformly doped sites within the ZIF-8 framework enable the reproducible and stable generation of composite materials with ideal iron species morphology, size, and carbon layer thickness. This forms the basis for the subsequent generation of uniform magnetic nanoparticles, ensuring their strong and stable macroscopic ferromagnetism. The magnetic ZIF-derived carbon composite material possesses a porous carbon framework uniformly loaded with iron-based active components, including zero-valent iron (Fe). 0 It contains iron(II) oxide and iron(III) oxide (Fe3O4); it has a mesoporous structure, high specific surface area, and is rich in hydroxyl (-OH) functional groups. It exhibits excellent heterogeneous Fenton catalytic performance in the aqueous environment and can be used to catalyze the degradation of tetracycline. Furthermore, due to the presence of iron(III) oxide, it can achieve rapid separation under an external magnetic field, enabling the reuse of catalytic materials. Attached Figure Description

[0010] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0011] Figure 1 These are SEM-EDS detection results from Example 1 of this invention, where (a) is the microstructure of the magnetic ZIF-derived carbon composite material, (b) is the C element distribution map, (c) is the N element distribution map, (d) is the O element distribution map, and (e) is the Fe element distribution map.

[0012] Figure 2 This is the Fourier transform infrared spectrum in Embodiment 1 of the present invention.

[0013] Figure 3 These are the adsorption / desorption curves and pore size analysis diagrams from Embodiment 1 of the present invention.

[0014] Figure 4 These are XPS spectra from Example 1 of the present invention, wherein (a) is the full spectrum of the magnetic ZIF-derived carbon composite material, (b) is the C element spectrum, (c) is the N element spectrum, (d) is the O element spectrum, and (e) is the Fe element spectrum.

[0015] Figure 5 This refers to the degradation effect and cycling results in Example 4 of the present invention.

[0016] Figure 6 This is the degradation rate result after 5 cycles in Example 1 of the present invention.

[0017] Figure 7 This is a technical roadmap of Embodiment 1 of the present invention. Detailed Implementation

[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, 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.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] One or more typical embodiments of the present invention provide a method for preparing magnetic ZIF-derived carbon composite materials, comprising the following steps: S1. Mix the iron source, zinc source and 2-methylimidazole in a solvent in a set ratio so that the molar ratio of iron, zinc and 2-methylimidazole is (1~2):(0~1):(10~14) to obtain a mixture; S2. Allow the mixture to stand and age for 48-72 hours, filter the solid product, and obtain the precursor. S3. Place the precursor in an inert atmosphere and heat it at 900~1100℃ for 2~3 hours to obtain the magnetic ZIF-derived carbon composite material.

[0021] Optionally, in S1, the iron source includes one or more of ferric nitrate nonahydrate, ferrous ammonium sulfate (NH4)2Fe(SO4)2•6H2O, and ferric acetylacetone (Fe(acac)3); ferric nitrate nonahydrate is preferred due to its high solubility, low byproduct interference, and availability; ferrous ammonium sulfate can provide Fe²⁺. + It can be used to synthesize iron species in different oxidation states; acetylacetone iron (Fe(acac)3) has good solubility in organic solvents and is suitable for synthesis in non-aqueous systems; when using iron salts other than ferric nitrate nonahydrate, other iron salts can be selected according to the experimental purpose (such as specific oxidation state, anion requirements, cost), and the synthesis parameters can be adjusted through preliminary experiments.

[0022] Optionally, in S1, the zinc source includes one or more of zinc nitrate hexahydrate and zinc acetate (Zn(CH3COO)2•2H2O); zinc nitrate is the "gold standard": due to its excellent solubility, high reproducibility, and extensive literature coverage, it is the best choice for initial synthesis or as a benchmark comparison; acetate ions have a buffering effect and can sometimes yield more homogeneous crystals; it is frequently used in synthesis in aqueous phase or methanol / water mixed solvents; when changing the zinc source, it is usually necessary to re-optimize the synthesis conditions (such as the molar ratio of zinc salt to ligand, solvent composition, reaction time, and temperature).

[0023] Optionally, in S1, the solvent can be selected from methanol system, water system and methanol / water mixed system solvent: methanol system solvent is the most commonly used mixed system, water system solvent has the characteristics of being green, low cost and suitable for large-scale production, methanol / water mixed system solvent is also commonly used, iron source, zinc source and 2-methylimidazole can be dissolved in the solvent, so that the concentration of 2-methylimidazole in the mixture is 0.3~0.6mol / L.

[0024] Optionally, in S1, the mixing method includes: preparing a metal salt solution containing an iron source and a zinc source, preparing a 2-methylimidazole solution, and then mixing and stirring the metal salt solution and the 2-methylimidazole solution for 4 to 6 hours.

[0025] Optionally, in S2, after filtering the solid product using a Buchner funnel, the product is vacuum dried overnight at 60-80°C to obtain the precursor.

[0026] Optionally, in S3, the inert atmosphere includes one or more of nitrogen, argon, and helium; nitrogen is the most economical and universal choice; argon is the standard choice for high purity and absolute inertness; helium is a choice with special properties and higher cost; the main purpose of using inert gases is to create an oxygen-free and water-free environment to prevent oxidation of metal precursors, decomposition of organic ligands, or destruction of the framework structure at high temperatures; the selection of inert gases is based on purity, cost, chemical inertness, safety, and specific process requirements.

[0027] One or more typical embodiments of the present invention provide a method for preparing the above-mentioned magnetic ZIF-derived carbon composite material to obtain a magnetic ZIF-derived carbon composite material.

[0028] The porous carbon framework of the ZIF-derived carbon composite material is uniformly loaded with iron-based active components; the iron-based active components include zero-valent iron (Fe). 0 Iron(II) and Fe3O4 (Fe3O4) are magnetic and can accumulate under the influence of an external magnetic field.

[0029] Optionally, the molar ratio of iron to zinc is (1~2):(0~1), preferably 2:1.

[0030] Optionally, it has a mesoporous structure, and according to BET test results, its specific surface area is 18~20 m². 2 The average pore volume is 0.06~0.08 cm³ / g, and hydroxyl functional groups are present on the surface.

[0031] One or more typical embodiments of the present invention provide the application of the above-mentioned magnetic ZIF-derived carbon composite material in the degradation of tetracycline in wastewater.

[0032] Because the composite material has a porous carbon skeleton, a mesoporous structure, a high specific surface area, and is rich in hydroxyl (-OH) functional groups, it can be used for the catalysis of heterogeneous Fenton reactions.

[0033] Optionally, the magnetic ZIF-derived carbon composite material degrades tetracycline under near-neutral conditions. The specific principle includes: efficient activation of hydrogen peroxide (H2O2); near-neutral conditions refer to a pH of 6.5.

[0034] Optionally, the concentration of the above-mentioned magnetic ZIF-derived carbon composite material added to water is 5~10 mg / L.

[0035] Optionally, after degradation, the magnetic ZIF-derived carbon composite material can be recovered by applying an external magnetic field.

[0036] Optionally, the regeneration method includes: washing repeatedly with anhydrous ethanol and ultrapure water, and drying in a vacuum drying oven at 60~80 ℃ for 6~8 hours.

[0037] The present invention will be further described below with reference to specific embodiments.

[0038] Example 1 A magnetic ZIF-derived carbon composite material is prepared by using ferric nitrate nonahydrate as the iron source, zinc nitrate hexahydrate as the zinc source, and water as the solvent. Figure 7 As shown, it includes the following steps: S1. Dissolve 15 mmol of a metal salt, including zinc nitrate hexahydrate and ferric nitrate nonahydrate in a molar ratio of 1:2, in 100 mL of ultrapure water to obtain a metal salt solution. Dissolve 60 mmol of 2-methylimidazole in 100 mL of ultrapure water to obtain a 0.6 mol / L 2-methylimidazole solution. Quickly pour the 2-methylimidazole solution into the metal salt solution and mix. Stir magnetically at room temperature for 4 h to obtain a mixture (i.e., a solution). The molar ratio of zinc, iron, and 2-methylimidazole is 1:2:12. S2. Allow the mixture to stand and age for 48 hours, filter the solid product using a Buchner funnel to obtain the precursor, and dry it overnight at 60°C for later use. S3. The precursor is heated in a nitrogen atmosphere at a heating rate of 5 °C / min, and heated to 1000 °C for 3 hours to complete carbonization and obtain a magnetic ZIF-derived carbon composite material, denoted as 66.6%Fe-ZIF-C, which means that the molar proportion of ferric nitrate nonahydrate in the metal salt is 66 / 6%.

[0039] The SEM-EDS detection results of the magnetic ZIF-derived carbon composite material obtained in this embodiment are as follows: Figure 1 As shown, Figure 1 Image (a) shows that iron particles of varying sizes, ranging from tens to hundreds of nanometers, are uniformly embedded in the ZIF-8-C material. Figure 1 (b) shows that the C element content is approximately 58.07%. Figure 1 (c) shows that the nitrogen content is approximately 0%. Figure 1 (d) shows that the content of O element is approximately 1.62%. Figure 1 (e) shows that the Fe content is approximately 40.31%. This proves the successful introduction of Fe and that the material surface is mainly composed of C and Fe.

[0040] The functional groups and chemical bonds of the magnetic ZIF-derived carbon composite material obtained in this embodiment were analyzed and detected using Fourier transform infrared spectroscopy. The results are as follows: Figure 2 As shown, at 1159 cm -1 1560 cm -1 3448 cm -1 A characteristic peak appeared nearby; 1159 cm. -1 The characteristic peaks appearing nearby are usually related to the stretching vibrations of the CO bond, indicating the possible presence of an ester (R-COO-R') functional group in the molecule; 1560 cm⁻¹ -1 The characteristic peaks appearing nearby are usually related to the stretching vibrations of the C=C bond and are typical absorption features of alkenes; 3448 cm⁻¹ -1The characteristic peaks that appear nearby are usually related to the stretching vibration of the OH bond, which indicates the presence of the -OH functional group in the molecule, which can be used for the catalysis of heterogeneous Fenton reactions.

[0041] The N2 adsorption-desorption curves and pore size analysis diagrams of the magnetic ZIF-derived carbon composite material obtained in this embodiment are shown below. Figure 3 As shown in the BET test results, the specific surface area of ​​ZIF-8-C is 2.042 m². 2 The average pore volume is 0.015517 cm³ / g, significantly lower than the specific surface area of ​​ZIF-8, which may be due to structural collapse during high-temperature carbonization. The nitrogen adsorption-desorption curve exhibits a clear hysteresis loop, typical of type IV isotherms, indicating the presence of mesoporous structures in ZIF-8-C. According to the pore size distribution diagram, the average pore size of ZIF-8-C is 19.8477 nm, classifying it as a mesoporous material. BET measurements show that the Fe3O4 / Fe... 0 The specific surface area of ​​ZIF-C is 18.094 m² / g, and the average pore volume is 0.067674 cm³ / g; this is due to the introduction of Fe, which increases the specific surface area and pore volume of the material.

[0042] Accordingly, the Fe3O4 / Fe ratio was measured. 0 -Nitrogen adsorption-desorption curves and pore size distribution diagram of ZIF-C; the nitrogen adsorption-desorption curves exhibit significant hysteresis, belonging to typical type IV isotherms, indicating Fe3O4 / Fe 0 -ZIF-C contains mesopores; based on the pore size distribution diagram, the Fe3O4 / Fe ratio is... 0 -ZIF-C has an average pore size of 9.0319 nm, making it a mesoporous material, and the pore size is smaller than that of ZIF-8-C. After Fe doping, the pore volume of the porous carbon material increases, the average pore size decreases, and the specific surface area increases.

[0043] The XPS spectrum of the magnetic ZIF-derived carbon composite material obtained in this embodiment is as follows: Figure 4 As shown, Figure 4 Image (a) shows that the surface of the prepared catalyst material contains four elements: C, N, O, and Fe. Figure 4 (b) shows that C1s has characteristic peaks at 284.8 eV, 286.2 eV, and 290.6 eV, corresponding to C=C, CO, and C=O, respectively. Figure 4 (c) shows that N1s has characteristic peaks at 400.74 eV, 405.64 eV, and 408.14 eV, corresponding to (C=O)-N-(C=O), -NO2, and (NO3)-, respectively. These are mainly pyridine N, and the presence of pyridine N can enhance the catalyst activity, thereby improving the degradation efficiency of organic matter. Figure 4(d) shows that O1s has characteristic peaks at 530.1 eV, 531.18 eV, and 532.66 eV, corresponding to O1s, respectively. 2- C=O and C-OH groups have a high surface oxygen content, which is highly correlated with catalytic activity. Figure 4 (e) shows that Fe2p has characteristic peaks at 707.95 eV, 710.85 eV, 719.87 eV, and 724.39 eV, with 707.95 eV corresponding to Fe... 0 Fe2p 3 / 2 The binding energy is at the peak of 710.85 eV with Fe. 2+ Fe2p 3 / 2 The binding energies correspond. The peaks at 719.87 eV and 724.39 eV correspond to Fe, respectively. 3+ Fe2p 3 / 2 and Fe 3+ Fe2p 1 / 2 The binding energy correspondence indicates that the material is composed of Fe. 2+ Fe 3+ and Fe 0 The composition, corresponding to the XRD results, ultimately revealed that Fe in the composite material exists as Fe3O4 and Fe2O3. 0 It exists, and Fe-ZIF-C is named Fe3O4 / Fe. 0 -ZIF-C.

[0044] Example 2 A magnetic ZIF-derived carbon composite material, the preparation method of which includes: 7.5 mmol zinc nitrate hexahydrate and 7.5 mmol ferric nitrate nonahydrate were dissolved in 100 mL of ultrapure water to obtain a metal salt solution; and 20 mmol 2-methylimidazole was dissolved in 100 mL of ultrapure water to obtain a 2-methylimidazole solution. After complete dissolution, the 2-methylimidazole solution was quickly poured into the metal salt solution, magnetically stirred at room temperature for 4 h, aged for 48 h, filtered through a 0.45 µm aqueous filter membrane using a Buchner funnel, and the resulting sample was dried overnight in a vacuum drying oven at 60 °C. The dried sample was ground and kept at 1000 °C for 3 h in a tube furnace with N2 as the protective gas and a heating rate of 5 °C / min. After cooling, the resulting magnetic ZIF-derived carbon composite material was denoted as 50%Fe-ZIF-C, which means that the molar proportion of ferric nitrate nonahydrate in the mixed metal salt (zinc nitrate and ferric nitrate) is 50%.

[0045] Example 3 A magnetic ZIF-derived carbon composite material, the preparation method of which includes: 15 mmol of ferric nitrate nonahydrate was dissolved in 100 mL of ultrapure water to obtain a metal salt solution; and 20 mmol of 2-methylimidazole was dissolved in 100 mL of ultrapure water to obtain a 2-methylimidazole solution. After complete dissolution, the 2-methylimidazole solution was quickly poured into the metal salt solution, magnetically stirred at room temperature for 4 h, aged for 48 h, filtered through a 0.45 µm aqueous filter membrane using a Buchner funnel, and the resulting sample was dried overnight in a vacuum drying oven at 60 °C. The dried sample was ground and kept at 1000 °C for 3 h in a tube furnace with N2 as the protective gas and a heating rate of 5 °C / min. After cooling, the resulting magnetic ZIF-derived carbon composite material was denoted as 100%Fe-ZIF-C, which means that the molar percentage of ferric nitrate nonahydrate in the metal salt solution is 100%.

[0046] Comparative Example 1 A catalytic composite material, the preparation method of which includes: 10 mmol zinc nitrate hexahydrate and 5 mmol ferric nitrate nonahydrate were dissolved in 100 mL of ultrapure water to obtain a metal salt solution; and 20 mmol 2-methylimidazole was dissolved in 100 mL of ultrapure water to obtain a 2-methylimidazole solution. After complete dissolution, the 2-methylimidazole solution was quickly poured into the metal salt solution, magnetically stirred at room temperature for 4 h, aged for 48 h, filtered through a 0.45 µm aqueous filter membrane using a Buchner funnel, and the resulting sample was dried overnight in a vacuum drying oven at 60 °C. The dried sample was ground and kept at 1000 °C for 3 h in a tube furnace with N2 as the protective gas and a heating rate of 5 °C / min. After cooling, the magnetic ZIF-derived carbon composite material was obtained, denoted as 33%Fe-ZIF-C, which means that the molar proportion of ferric nitrate nonahydrate in the mixed metal salt (zinc nitrate and ferric nitrate) is 33%.

[0047] Comparative Example 2 A catalytic composite material, the preparation method of which includes: 15 mmol zinc nitrate hexahydrate was dissolved in 100 mL of ultrapure water to obtain a metal salt solution; and 60 mmol 2-methylimidazole was dissolved in 100 mL of ultrapure water to obtain a 2-methylimidazole solution. After complete dissolution, the 2-methylimidazole solution was quickly poured into the metal salt solution, magnetically stirred at room temperature for 4 h, aged for 48 h, filtered through a 0.45 µm aqueous filter membrane using a Buchner funnel, and the resulting sample was dried overnight in a vacuum drying oven at 60 °C. The dried sample was ground and held at 1000 °C for 3 hours in a tube furnace with N2 as the protective gas and a heating rate of 5 °C / min. After cooling, the magnetic ZIF-derived carbon composite material, ZIF-8, was obtained. ZIF-8 refers to the ZIF-8 material that already existed in the prior art before the introduction of the iron source.

[0048] Example 4 A method for degrading tetracycline in wastewater includes: preparing an aqueous dispersion of tetracycline with a concentration of 50 mg / L; adding catalyst materials from Examples 1-3 or Comparative Examples 1-2 to the dispersion at a concentration of 5 mg / L; detecting the concentration of tetracycline in the water after 15 minutes and calculating the initial degradation rate; then recovering the catalyst material by applying an external magnetic field; washing it several times with anhydrous ethanol and ultrapure water; drying it in a vacuum drying oven at 60 ℃ for 6 h; completing the regeneration process of the catalyst material to obtain the regenerated catalyst material; recycling the catalyst material; repeating the process five times; and calculating the degradation rate after each recovery.

[0049] Initial degradation rate such as Figure 5 As shown, ZIF-8-C and 33.3% Fe-ZIF-C exhibited low catalytic degradation efficiency for tetracycline hydrochloride, reaching degradation equilibrium at approximately 120 min, with TC degradation rates of 57.4% and 72%, respectively. 50% Fe-ZIF-C and 100% Fe-ZIF-C reached degradation equilibrium at approximately 30 min, with TC degradation rates of 85% and 90%, respectively. 66.6% Fe-ZIF-C showed high catalytic degradation efficiency for tetracycline hydrochloride, reaching equilibrium at approximately 20 min. The degradation equilibrium was reached at 96.2% within 1 minute. The reason for this is that in the heterogeneous Fenton catalytic reaction, ZIF-8-C, as a pure carbon material, lacks the synergistic effect of iron ions, resulting in insufficient catalytic degradation of TC. While the degradation capacity for TC gradually increases with increasing Fe content in the catalyst, 100% Fe-ZIF-C, lacking Zn ions during synthesis, loses its pore-forming ability due to Zn volatilization during carbonization. Therefore, the catalytic efficiency of pure iron catalysts for tetracycline hydrochloride is lower than that of 66.6% Fe-ZIF-C. The material with better catalytic performance is 66.6% Fe-ZIF-C, which also continues to participate in subsequent catalytic reactions as a catalyst.

[0050] Based on the degradation rate results after 5 cycles in Example 1, a graph was plotted with the number of cycles on the x-axis and the TC degradation rate on the y-axis to examine the reusability of the catalyst. Figure 6 As shown, the degradation rate of TC gradually decreases with the progress of the cycle. In the first three cycles, the degradation rate of TC was above 90%, which may be due to the Fe3O4 / Fe... 0The ZIF-C structure effectively slows down iron ion precipitation; the TC degradation rate remained at 70.9% after the fourth cycle, but only 45.1% after the fifth cycle. This is likely due to the Fe3O4 / Fe ratio during the catalytic degradation reaction. 0 The partial leaching of the active Fe element in the ZIF-C structure leads to the loss of effective components and reduces the Fe3O4 / Fe ratio. 0 The catalytic activity of ZIF-C is limited; secondly, the presence and valence of Fe and the surface chemistry of the catalyst may change adversely as the reaction proceeds, leading to a gradual decrease in catalyst activity. However, overall, the degradation rate of this catalyst can still be maintained above 70% after four uses, demonstrating good stability and cycle life.

[0051] Compared with the existing ZIF-8-derived highly dispersed bimetallic Fe-Ni-NC catalytic materials, this invention uses only a single metal doping ZIF-8 to improve the degradation efficiency of tetracycline; and the synthesis method is simpler; the specific method for degrading tetracycline is the heterogeneous Fenton catalysis, the co-catalyst is hydrogen peroxide, the catalytic environment is a near-neutral environment, the pH adaptation range is wide, which can reduce the harm to the environment and is more environmentally friendly.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a magnetic ZIF-derived carbon composite material, characterized in that, Includes the following steps: S1. Mix the iron source, zinc source and 2-methylimidazole in a solvent so that the molar ratio of iron, zinc and 2-methylimidazole is (1~2):(0~1):(10~14) to obtain a mixture; S2. Allow the mixture to stand and age for 48-72 hours, filter the solid product, and obtain the precursor. S3. Place the precursor in an inert atmosphere and heat it at 900~1100℃ for 2~3 hours to obtain the magnetic ZIF-derived carbon composite material.

2. The method for preparing the magnetic ZIF-derived carbon composite material as described in claim 1, characterized in that, In S1, the iron source includes one or more of ferric nitrate nonahydrate, ferrous ammonium sulfate, and ferric acetylacetone; Alternatively, the zinc source may include one or more of zinc nitrate hexahydrate and zinc acetate.

3. The method for preparing the magnetic ZIF-derived carbon composite material as described in claim 1, characterized in that, In S1, the solvent includes one or more of methanol system, water system and methanol / water mixture; the concentration of 2-methylimidazole in the mixture is 0.3~0.6 mol / L; Alternatively, in S1, the mixing method includes: preparing a metal salt solution containing an iron source and a zinc source, preparing a 2-methylimidazole solution, and then mixing and stirring the metal salt solution and the 2-methylimidazole solution for 4 to 6 hours; Alternatively, in S2, after filtering the solid product using a Buchner funnel, the precursor is obtained by vacuum drying at 60-80°C overnight.

4. The method for preparing the magnetic ZIF-derived carbon composite material as described in claim 1, characterized in that, In S3, the inert atmosphere includes one or more of nitrogen, argon, and helium.

5. A magnetic ZIF-derived carbon composite material prepared by the method described in any one of claims 1-4, characterized in that, The porous carbon framework is uniformly loaded with iron-based active components; the iron-based active components include zero-valent iron and iron(III) oxide.

6. The magnetic ZIF-derived carbon composite material as described in claim 5, characterized in that, The molar ratio of iron to zinc is (1~2):(0~1), preferably 2:

1.

7. The magnetic ZIF-derived carbon composite material as described in claim 5, characterized in that, It has a mesoporous structure and a specific surface area of ​​18~20 m². 2 The average pore volume is 0.06~0.08 cm³ / g, and hydroxyl functional groups are present on the surface.

8. The application of a magnetic ZIF-derived carbon composite material as described in any one of claims 5-7 in the degradation of tetracycline in wastewater.

9. The application as described in claim 8, characterized in that, Degrades tetracycline under near-neutral conditions.

10. The application as described in claim 8, characterized in that, The magnetic ZIF-derived carbon composite material is added to water at a concentration of 5-10 mg / L.

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