A metal organic framework ZIF-8 derived fenton-like catalyst, and a preparation method and application thereof

Abstract

This invention discloses a ZIF-8-derived Fenton-like catalyst with a metal-organic framework, its preparation method, and its applications. This ZIF-8-derived Fenton-like catalyst retains the high specific surface area and well-developed microporous structure of ZIF-8-derived carbon materials, enabling rapid adsorption of phenol pollutants in water with a high phenol degradation and removal rate exceeding 90%. It also provides a large number of catalytic active sites. The doped Cu is uniformly dispersed at the atomic level, forming a Cu-N strong coordination structure, effectively inhibiting metal agglomeration and ion dissolution, significantly improving the catalyst's cycle stability and resistance to metal leaching, and exhibiting excellent recyclability.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more particularly to a ZIF-8 metal-organic framework-derived Fenton-like catalyst, its preparation method, and its application. Background Technology

[0002] Advanced oxidation technologies for persulfates (including permonosulfate PMS and perdisulfate PDS) have become a research hotspot in the field of water treatment in recent years. Persulfates themselves have relatively weak oxidizing power at room temperature, but after appropriate activation, they can generate sulfate radicals (SO4· ... - With an oxidation potential of 2.5–3.1 V, it can efficiently degrade organic pollutants in water. Common activation methods include thermal activation, ultraviolet activation, transition metal ion activation, and carbon-based material catalytic activation.

[0003] Phenol is a typical toxic and recalcitrant organic compound, widely found in wastewater from industries such as coking, petrochemicals, pharmaceuticals, plastics, and dyeing. Phenol and its derivatives exhibit high levels of biotoxicity, mutagenicity, and carcinogenicity, and have been listed as priority pollutants in my country and several other countries. Due to the relative stability of the aromatic rings in phenol's structure, conventional physical adsorption or biological treatment methods are insufficient for its complete mineralization, often resulting in the formation of even more toxic intermediates. Therefore, developing catalysts capable of efficiently activating persulfate and deeply degrading phenol is of significant environmental importance.

[0004] Studies have found that persulfate activation involves two degradation pathways: free radical and non-free radical. The non-free radical pathway effectively avoids background interference from water anions and natural organic matter, exhibiting excellent selectivity for phenol degradation. High-valence metal active species are the core intermediates constituting non-free radical oxidation, mainly including Fe(IV) / Fe(V), Co(IV), and Cu(III). Compared to other high-valence metal species, Cu(III) combines high oxidizing activity with low biotoxicity, and can enhance the degradation of organic pollutants through multiple reaction pathways. Homogeneous copper-based catalytic systems have high activation efficiency, but suffer from drawbacks such as large metal ion dissolution, inability to recover, and susceptibility to secondary pollution. Conventional heterogeneous copper-based catalysts generally suffer from severe active metal agglomeration, poor dispersion of active sites, low site utilization, and difficulty in controlling microporous structures, which restricts their practical engineering applications.

[0005] Metal-organic framework (MOF)-derived carbon materials retain the regular framework structure of MOF precursors while possessing excellent chemical stability and electronic conductivity, making them ideal catalytic precursors for Fenton-like advanced oxidation technologies. ZIF-8, a classic zinc-based zeolite imidazole ester framework material, is assembled from zinc ions and 2-methylimidazolium. It features a regular topological structure, readily available and inexpensive raw materials, mild synthesis conditions, and a large specific surface area. After high-temperature pyrolysis and carbonization, it can be transformed into a nitrogen-doped porous carbon-based material with well-developed channels, abundant surface defects, and various types of nitrogen functional groups. Currently, conventional ZIF-8-derived catalysts still have many shortcomings: preparation often relies on staged pyrolysis under an inert atmosphere, resulting in complex processes and high costs; particle agglomeration easily occurs after metal doping, leading to uneven distribution of active components, high metal ion leaching rates, and poor cycle stability; the specific surface area, pore structure, and degree of graphitization of the catalyst are difficult to precisely control; the interaction mechanism between free radicals and non-free radicals in the degradation of phenol by activated persulfate is unclear, and the long-term operational stability of the catalyst needs further improvement.

[0006] To address the shortcomings of existing technologies, a method for preparing ZIF-8-derived activated persulfate Fenton catalysts is developed. This method features a simple preparation process, low metal ion dissolution, atomic-level dispersion of active metals, suitable pore structure, high catalytic activity, and excellent cycle stability. It enables efficient and deep treatment of phenol-containing industrial wastewater and has significant theoretical research value and engineering application prospects. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a Fenton-like catalyst derived from a metal-organic framework ZIF-8.

[0008] Another object of the present invention is to provide a method for preparing a Fenton-like catalyst derived from a metal-organic framework ZIF-8.

[0009] Another objective of this invention is to provide an application of a ZIF-8-derived Fenton-like catalyst in activated persulfate-degraded phenol wastewater.

[0010] To achieve the above objectives, the present invention is accomplished through the following technical solutions.

[0011] A Fenton-like catalyst derived from a metal-organic framework ZIF-8, the Fenton-like catalyst comprising a nitrogen-doped carbon framework and copper uniformly dispersed in the nitrogen-doped carbon framework in an atomic state through Cu-N coordination bonds, the nitrogen-doped carbon framework being composed of 2-methylimidazole and zinc nitrate hexahydrate.

[0012] In the above technical solution, the Fenton-like catalyst has an amorphous porous carbon structure.

[0013] In the above technical solution, the specific surface area of ​​the Fenton-like catalyst is 970~1170 m². 2 / g, with an average pore size of 1.2~1.6 nm.

[0014] A method for preparing a ZIF-8-derived Fenton-like catalyst from a metal-organic framework includes the following steps: Step 1: Dissolve 2-methylimidazole in a first organic solvent to obtain a ligand solution; dissolve zinc nitrate hexahydrate and copper salt in a second organic solvent to obtain a metal salt solution; under stirring conditions, add the metal salt solution to the ligand solution and allow the reaction to proceed at room temperature for 6-12 hours; after the reaction is completed, perform post-processing to obtain the Cu-doped ZIF-8 precursor; wherein the molar ratio of 2-methylimidazole, zinc nitrate hexahydrate, and copper salt is (1200-1400):(5-50):(1-4). In step 1, the copper salt is at least one of copper acetylacetonate, copper chloride, copper nitrate, and copper sulfate.

[0015] In step 1, the first organic solvent includes methanol; the second organic solvent includes methanol.

[0016] In step 1, the preferred settling time is 4 to 8 hours.

[0017] In step 1, the molar ratio of the 2-methylimidazole to the volume fraction of the first organic solvent is (60~80):100, where the molar ratio is in mmol and the volume fraction is in mL.

[0018] In step 1, the molar ratio of zinc nitrate hexahydrate to the volume ratio of the second organic solvent is 2:100, where the molar ratio is in mmol and the volume ratio is in mL.

[0019] Step 2: Under an inert atmosphere, the Cu-doped ZIF-8 precursor is pyrolyzed and carbonized at 800~950 ℃ for 1~3 h, cooled, and ground to obtain the pyrolysis product; In step 2, an inert gas is introduced to purge and remove the air to form an inert atmosphere. The inert gas is high-purity nitrogen or argon, and the gas flow rate is 50~150 mL / min.

[0020] In step 2, the temperature is increased to 800-950 ℃ at a heating rate of 3-8 ℃ / min and then pyrolyzed and carbonized at 800-950 ℃ for 1-3 h.

[0021] In step 2, the cooling is natural cooling to room temperature.

[0022] Step 3: Disperse the pyrolysis product in an acid solution and let it stand at 40-80 °C for 4-6 hours to remove unstable metal nanoparticles or oxides. After post-processing, a metal-organic framework ZIF-8-derived Fenton-like catalyst is obtained.

[0023] In step 3, the acid solution is a 0.5-3 mM sulfuric acid solution or hydrochloric acid solution.

[0024] In steps 1 and 3, the post-processing operation consists of centrifugation, washing, and vacuum drying in sequence.

[0025] In the above technical solution, in step 1, the sample is washed with methanol 3 to 4 times; in step 3, it is washed with deionized water until neutral.

[0026] In the above technical solution, the vacuum drying temperature is 40~80 ℃, and the vacuum drying time is 8~12 h.

[0027] Application of a ZIF-8 metal-organic framework-derived Fenton-like catalyst in activated persulfate degradation of phenol wastewater.

[0028] In the above technical solution, the dosage of the Fenton-like catalyst is 0.05~0.5 g / L, the persulfate concentration is 0.5~5 mM, and the pH of the phenol industrial wastewater is 3~9.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in this invention retains the high specific surface area and well-developed microporous structure characteristics of ZIF-8-derived carbon materials, which can quickly adsorb phenol pollutants in water and provide a large number of catalytic active sites. The doped Cu is uniformly dispersed at the atomic level to form a Cu-N strong coordination structure, which effectively inhibits metal agglomeration and ion dissolution, and significantly improves the catalyst's cycle stability and resistance to metal leaching.

[0030] (2) The metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in this invention can efficiently activate persulfate or perdisulfate, relying on Cu(III) and 1 The O2-synergistic non-radical degradation pathway has strong resistance to interference from background impurities in water bodies, a wide pH range, and a high phenol degradation and removal rate of over 90%, making it suitable for the deep treatment of various industrial wastewater containing phenol.

[0031] (3) The metal-organic framework ZIF-8-derived Fenton-like catalyst prepared by this invention has excellent recyclability and high catalytic activity after multiple reuses. It has low metal dissolution rate, no secondary pollution, low operation and maintenance cost, and significant engineering application value.

[0032] (4) The preparation method of the present invention adopts an integrated process of "solvent thermal synthesis-impregnation doping-high temperature pyrolysis", which is simple, has low preparation cost, and is easy to industrialize and mass-produce. Attached Figure Description

[0033] Figure 1 Scanning electron microscopy analysis of the ZIF-8 metal-organic framework-derived Fenton-like catalyst prepared in Example 2; Figure 2 (a) Nitrogen adsorption-desorption specific surface area and (b) pore size analysis diagram of the ZIF-8 metal-organic framework-derived Fenton-like catalyst prepared in Example 2; Figure 3 Fourier transform infrared spectrum of the ZIF-8 metal-organic framework-derived Fenton-like catalyst prepared in Example 2; Figure 4 The effect of different quenchers on the activation of persulfate by the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 on the removal of phenol; Figure 5 The electron paramagnetic resonance (EPR) spectra of different reactive oxygen species generated by the activation of the persulfate system by the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 are shown, where (a) is •OH / SO4. ·- The free radical signal spectrum, (b) is 1 O2 free radical signal spectrum; Figure 6 The effect of different premixing times of the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 on phenol removal; Figure 7 The Raman spectrum of the persulfate system activated by the ZIF-8 metal-organic framework-derived Fenton-like catalyst prepared in Example 2; Figure 8 The effect of different inorganic anions and HA on the activation of the persulfate system by the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 on the removal of phenol; Figure 9 The effect of different initial pH values ​​on the activation of the persulfate system by the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 on the removal of phenol; Figure 10 The image shows the effect of the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 on the cyclic removal of phenol from the persulfate system. Detailed Implementation

[0034] The following examples are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0035] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0036] Example 1 A method for preparing a ZIF-8-derived Fenton-like catalyst from a metal-organic framework includes the following steps: Step 1, Preparation of copper-doped ZIF-8 composite material: 70 mmol of 2-methylimidazole was dissolved in 100 mL of methanol to obtain a ligand solution; 2 mmol of zinc nitrate hexahydrate and 0.05 mmol of copper chloride were dissolved in 100 mL of methanol to obtain a metal salt solution; under stirring conditions, the metal salt solution was rapidly added to the ligand solution, and the reaction was allowed to proceed at room temperature for 12 hours; after the reaction was completed, the solid was centrifuged, washed three times with methanol, and dried under vacuum at 80 °C for 8 h to obtain the Cu-doped ZIF-8 precursor; Step 2, high-temperature pyrolysis to prepare catalyst: Cu-doped ZIF-8 precursor was placed in a tube furnace, and high-purity nitrogen was introduced at a gas flow rate of 120 mL / min to purge the air. Under an inert atmosphere, the temperature was raised to 800℃ at a heating rate of 6℃ / min and pyrolyzed and carbonized at 800℃ for 3 h. After natural cooling to room temperature, the product was ground to obtain the pyrolysis product. Step 3, acid washing and purification: The pyrolysis product was dispersed in a 3 mM sulfuric acid solution and allowed to stand at 40°C for 6 hours to remove unstable metal nanoparticles or oxides. Then, the product was centrifuged, and the collected solid was washed with deionized water until neutral. It was then vacuum dried at 80°C for 10 hours to obtain the metal-organic framework ZIF-8-derived Fenton-like catalyst.

[0037] Example 2 A method for preparing a ZIF-8-derived Fenton-like catalyst from a metal-organic framework includes the following steps: Step 1, Preparation of copper-doped ZIF-8 composite material: 60 mmol of 2-methylimidazole was dissolved in 100 mL of methanol to obtain a ligand solution; 2 mmol of zinc nitrate hexahydrate and 0.2 mmol of copper acetylacetonate were dissolved in 100 mL of methanol to obtain a metal salt solution; under stirring conditions, the metal salt solution was rapidly added to the ligand solution, and the reaction was allowed to proceed at room temperature for 6 hours; after the reaction was completed, the solid was centrifuged, washed three times with methanol, and dried under vacuum at 60 °C for 12 h to obtain the Cu-doped ZIF-8 precursor; Step 2, high-temperature pyrolysis to prepare catalyst: The Cu-doped ZIF-8 precursor was placed in a tube furnace, and argon gas was introduced at a flow rate of 80 mL / min to purge the air. Under an inert atmosphere, the temperature was increased to 900℃ at a heating rate of 4℃ / min and pyrolyzed and carbonized at 900℃ for 1.5 h. After natural cooling to room temperature, the product was ground to obtain the pyrolysis product. Step 3, acid washing and purification: The pyrolysis product was dispersed in 1 mM hydrochloric acid solution and allowed to stand at 80°C for 4 hours to remove unstable metal nanoparticles or oxides. Then, the product was centrifuged, and the collected solid was washed with deionized water until neutral. It was then vacuum dried at 60°C for 12 h to obtain the metal-organic framework ZIF-8-derived Fenton-like catalyst.

[0038] Comparative Example 1 A method for preparing a ZIF-8-derived Fenton-like catalyst from a metal-organic framework includes the following steps: Step 1, Preparation of copper-doped ZIF-8 composite material: 80 mmol of 2-methylimidazole was dissolved in 100 mL of methanol to obtain a ligand solution; 2 mmol of zinc nitrate hexahydrate and 0.1 mmol of copper nitrate were dissolved in 100 mL of methanol to obtain a metal salt solution; under stirring conditions, the metal salt solution was rapidly added to the ligand solution, and the reaction was allowed to proceed at room temperature for 8 hours; after the reaction was completed, the solid was centrifuged, washed three times with methanol, and dried under vacuum at 70 °C for 10 h to obtain the Cu-doped ZIF-8 precursor; Step 2, high-temperature pyrolysis to prepare catalyst: Cu-doped ZIF-8 precursor was placed in a tube furnace, and high-purity nitrogen was introduced at a gas flow rate of 100 mL / min to purge the air. Under an inert atmosphere, the temperature was raised to 900℃ at a heating rate of 5℃ / min and pyrolyzed and carbonized at 900℃ for 2 h. After natural cooling to room temperature, the product was ground to obtain the pyrolysis product. Step 3, acid washing and purification: The pyrolysis product was dispersed in 2 mM sulfuric acid solution and allowed to stand at 60°C for 5 hours to remove unstable metal nanoparticles or oxides. Then, the product was centrifuged, and the collected solid was washed with deionized water until neutral. It was then vacuum dried at 70°C for 12 hours to obtain the metal-organic framework ZIF-8-derived Fenton-like catalyst.

[0039] Comparative Example 2 A method for preparing a ZIF-8-derived Fenton-like catalyst from a metal-organic framework includes the following steps: Step 1, Preparation of copper-doped ZIF-8 composite material: 80 mmol of 2-methylimidazole was dissolved in 100 mL of methanol to obtain a ligand solution; 2 mmol of zinc nitrate hexahydrate and 0.1 mmol of copper sulfate were dissolved in 100 mL of methanol to obtain a metal salt solution; under stirring conditions, the metal salt solution was rapidly added to the ligand solution, and the reaction was allowed to proceed at room temperature for 8 hours; after the reaction was completed, the solid was centrifuged, washed three times with methanol, and dried under vacuum at 70 °C for 10 h to obtain the Cu-doped ZIF-8 precursor; Step 2, high-temperature pyrolysis to prepare catalyst: Cu-doped ZIF-8 precursor was placed in a tube furnace, and high-purity nitrogen was introduced at a gas flow rate of 100 mL / min to purge the air. Under an inert atmosphere, the temperature was raised to 900℃ at a heating rate of 5℃ / min and pyrolyzed and carbonized at 900℃ for 2 h. After natural cooling to room temperature, the product was ground to obtain the pyrolysis product. Step 3, acid washing and purification: The pyrolysis product was dispersed in 2 mM sulfuric acid solution and allowed to stand at 60°C for 5 hours to remove unstable metal nanoparticles or oxides. Then, the product was centrifuged, and the collected solid was washed with deionized water until neutral. It was then vacuum dried at 70°C for 12 hours to obtain the metal-organic framework ZIF-8-derived Fenton-like catalyst.

[0040] The ZIF-8-derived Fenton-like catalyst derived from the metal-organic framework prepared in Example 2 was analyzed by scanning electron microscopy and nitrogen adsorption-desorption specific surface area and pore size analysis. The results are as follows: Figures 1-2 As shown, by Figures 1-2 It can be seen that the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 has an amorphous porous carbon structure with a specific surface area of ​​970~1170 m². 2 / g, mainly microporous, with an average pore size of about 1.5 nm.

[0041] Fourier transform infrared spectroscopy analysis was performed on the ZIF-8-derived Fenton-like catalyst prepared in Example 2, and the results are as follows: Figure 3 As shown, combined with Figure 1 and Figure 3 It can be seen that Cu is uniformly dispersed in the nitrogen-doped carbon framework in an atomic state, forming Cu-N coordination bonds, and there is no obvious aggregation of copper nanoparticles.

[0042] Test Example 1 Degradation of micropollutants experiment: 100 mL of a 50 mg / L phenol aqueous solution (pH=6.35) was prepared and placed in a 250 mL beaker. The reaction was carried out in a water bath at 25°C with a stirring frequency of 300 rpm. 0.25 mM persulfate and 100 mg / L catalyst were added to the phenol aqueous solution to initiate the reaction. The catalyst was one of the ZIF-8-derived Fenton-like catalysts derived from the metal-organic framework prepared in Examples 1-2 and Comparative Examples 1-2. After the reaction started, samples were taken every 2 minutes, with 1 mL taken each time as the test solution. Immediately after sampling, 50 μL of 0.1 mol / L Na2S2O3 aqueous solution was added to the test solution to terminate the reaction. The solution was filtered through a 0.22 μm PTFE membrane, and the concentration of phenol in the test solution after catalyst treatment was determined by high performance liquid chromatography (HPLC). The results are shown in Table 1.

[0043] Table 1

[0044] After the reaction was completed (10 min), 10 mL of sample was taken and the dissolution of copper was determined by flame atomic absorption spectrometry. No copper dissolution was detected in Examples 1-2 and Comparative Examples 1-2.

[0045] Test Example 2 Quencher-free experiment: The Fenton-like catalyst derived from the metal-organic framework ZIF-8 prepared in Example 2 was used as the "catalyst" in the "Degradation of Micropollutants Experiment" to evaluate the degradation performance of phenol activated by persulfate. Figure 4 "Control" in Chinese.

[0046] Three parallel experiments were conducted following the above experiment without quencher: In the parallel experiments, a quencher was added along with persulfate. The quencher was one of methanol (MeOH), furfuryl alcohol (FFA), and superoxide dismutase (SOD). The final concentration of methanol was 250 mM, the final concentration of furfuryl alcohol was 20 mM, and the final concentration of superoxide dismutase was 20 U / mL.

[0047] Sulfate radicals SO4 in the system were quenched by adding MeOH. ·- And hydroxyl radicals (·OH), added to the FFA quenching system 1 O2, added to the SOD quenching system to eliminate superoxide radicals. 2- To detect the active substances involved in the degradation reaction, the results are as follows: Figure 4 As shown, by Figure 4 It can be seen that, compared with the absence of a quencher, the degradation performance after adding MeOH remained almost unchanged, the addition of SOD showed little change, and the addition of FFA significantly reduced the degradation performance, indicating the presence of [a quencher] in the system.1 O2 participates in degradation. 1 O2 is the main active substance in the degradation process.

[0048] Test Example 3 2,6-Dimethylpyridine N-oxide (DMPO) was chosen as SO4. ·- And ·OH scavenger, 4-amino-2,2,6,6-tetramethylpiperidine (TEMP) as 1 Electron spin resonance (EPR) measurements were performed using O2 trapping agents. Results are as follows: Figure 5 As shown, by Figure 5 As shown in (a), no •OH / SO4 was detected in the electron paramagnetic resonance spectrum of the ZIF-8-derived Fenton-like catalyst prepared in Example 2. ·- Free radical signal. (From) Figure 5 As can be seen from (b), a significant electron paramagnetic resonance spectrum can be observed in the Fenton-like catalyst derived from the metal-organic framework ZIF-8 prepared in Example 2. 1 The 1:1:1 triplet characteristic ESR signal of O2 further illustrates that the ZIF-8-derived Fenton-like catalyst derived from the metal-organic framework prepared in Example 2 generates a large amount of O2 during the catalytic degradation reaction. 1 O2 reactive oxygen species.

[0049] Test Example 4 Premixing experiments are used to determine whether an electron transfer process exists in the system.

[0050] Premixing experiment: 0.25 mM persulfate and 100 mg / L catalyst were first added to deionized water and pre-stirred for 5 or 10 min. Then, phenol was added to start the reaction. The concentration of phenol in deionized water was 50 mg / L. After the reaction started, samples were taken at 0 min, 1 min, 2.5 min, 5 min, 7.5 min, 10 min, and 15 min, with 1 mL taken each time as the test solution. Immediately after sampling, 50 μL of 0.1 mol / L Na2S2O3 aqueous solution was added to the test solution to terminate the reaction. The solution was filtered through a 0.22 μm PTFE membrane, and the concentration of phenol in the test solution after catalyst treatment was determined by HPLC. The degradation effect after 5 min of pre-stirring is as follows: Figure 6 As shown in "Premix for 5 min", the degradation effect of pre-stirring for 10 min is as shown in "Premix for 10 min".

[0051] Following the premixing experiment described above, parallel experiments were then conducted: in the parallel experiments, phenol, PMS, and the catalyst were added simultaneously as... Figure 6 "Premix for 0 minutes" in the middle.

[0052] Depend on Figure 6It can be seen that the inhibition of phenol removal effect is enhanced with the increase of premixing time, which indicates that there is no non-radical pathway for pollutant-mediated electron transfer process in the system.

[0053] In-situ Raman spectroscopy was used to detect high-valence metal species in the system after 15 min of reaction in a "premixed 0 min" state. Results are as follows: Figure 7 As shown, by Figure 7 It can be seen that high-valence copper non-radical species Cu(III) are generated during the reaction.

[0054] Test Example 5 To investigate the effects of coexisting anions and natural organic matter in the pollutant solution on the reaction system, appropriate concentrations of chemical reagents were added to the phenol aqueous solution before the addition of persulfate. These reagents were sodium chloride (NaCl), sodium nitrate (NaNO3), sodium dihydrogen phosphate (NaH2PO4), and humic acid (HA). The final concentrations of NaCl, NaNO3, and NaH2PO4 in the phenol aqueous solution were 50 mM, and the final concentration of HA was 2 mM. The metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 was used as the "catalyst" in the "premixing experiment (premixing 0 min)" to assess the degradation performance of phenol activated by persulfate. Figure 8 "Comparison" in Chinese.

[0055] Depend on Figure 8 It can be seen that none of the coexisting anions have a significant effect on the removal rate of phenol.

[0056] Test Example 6 The effect of pH value of the pollutant solution on degradation performance was investigated. When the pH of the phenol aqueous solution was 3, 5, 6.35, 7, or 9, the ZIF-8-derived Fenton-like catalyst prepared in Example 2 was used as the "catalyst" in the "premixing experiment (premixing 0 min)" to activate and degrade the pollutant using persulfate. The degradation performance was as follows: Figure 9 As shown, the pH value of the pollutant solution is adjusted using dilute sulfuric acid or sodium hydroxide aqueous solution, wherein the concentration of H2SO4 in the dilute sulfuric acid is 0.1 M, and the concentration of sodium hydroxide (NaOH) in the sodium hydroxide aqueous solution is 0.1 M.

[0057] Depend on Figure 9 It can be seen that the degradation performance of phenol by the metal-organic framework ZIF-8-derived Fenton-like catalyst prepared in Example 2 is basically not inhibited by pH.

[0058] Test Example 7 The ZIF-8 metal-organic framework-derived Fenton-like catalyst prepared in Example 2 was used as the "catalyst" in the "premixing experiment (premixing 0 min)" to activate and degrade phenol with persulfate. The reacted catalyst was collected by vacuum filtration and vacuum drying at 50°C for 4 hours to serve as the catalyst sample for the next premixing experiment (premixing 0 min). The above steps were repeated 5 times to evaluate the catalyst recycling effect. Since catalyst loss may occur during the recovery process, multiple parallel experiments were conducted under the same conditions to ensure sufficient catalyst for multiple experiments. This allowed for the collection of more catalyst samples, ensuring the reliability and accuracy of the experiments. The average value of the results from multiple parallel experiments was plotted. Figure 10 The result is as follows Figure 10 As shown, by Figure 10 It is known that the Fenton-like catalyst derived from the metal-organic framework ZIF-8 is recyclable and has excellent performance.

[0059] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A Fenton-like catalyst derived from a metal-organic framework ZIF-8, characterized in that, The Fenton-like catalyst comprises a nitrogen-doped carbon framework and copper uniformly dispersed in the nitrogen-doped carbon framework in an atomic state through Cu-N coordination bonds. The nitrogen-doped carbon framework is composed of 2-methylimidazole and zinc nitrate hexahydrate.

2. The Fenton-like catalyst according to claim 1, characterized in that, The Fenton-like catalyst has an amorphous porous carbon structure.

3. The Fenton-like catalyst according to claim 1, characterized in that, The specific surface area of ​​the Fenton-like catalyst is 970~1170 m². 2 / g, with an average pore size of 1.2~1.6 nm.

4. The method for preparing the ZIF-8-derived Fenton-like catalyst of the metal-organic framework as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Dissolve 2-methylimidazole in a first organic solvent to obtain a ligand solution; dissolve zinc nitrate hexahydrate and copper salt in a second organic solvent to obtain a metal salt solution; add the metal salt solution to the ligand solution under stirring, and then allow the reaction to stand at room temperature for 6-12 hours. After the reaction is completed, perform post-processing to obtain the Cu-doped ZIF-8 precursor; wherein the molar ratio of 2-methylimidazole, zinc nitrate hexahydrate and copper salt is (1200-1400):(5-50):(1-4). Step 2: Under an inert atmosphere, the Cu-doped ZIF-8 precursor is pyrolyzed and carbonized at 800~950 ℃ for 1~3 h, cooled, and ground to obtain the pyrolysis product; Step 3: Disperse the pyrolysis product in an acid solution and let it stand at 40-80 °C for 4-6 hours. After post-processing, obtain the metal-organic framework ZIF-8-derived Fenton-like catalyst.

5. The preparation method according to claim 4, characterized in that, The copper salt is at least one of copper acetylacetonate, copper chloride, copper nitrate, and copper sulfate.

6. The preparation method according to claim 4, characterized in that, The first organic solvent includes methanol; the second organic solvent includes methanol.

7. The preparation method according to claim 4, characterized in that, An inert atmosphere is formed by purging and removing air with an inert gas, wherein the inert gas is high-purity nitrogen or argon, and the gas flow rate is 50~150 mL / min.

8. The preparation method according to claim 4, characterized in that, The acid solution is a 0.5~3 mM sulfuric acid solution or hydrochloric acid solution; The post-processing operation consists of centrifugation, washing, and vacuum drying in sequence. The vacuum drying temperature is 40~80 ℃, and the vacuum drying time is 8~12 h.

9. The application of the ZIF-8 metal-organic framework-derived Fenton-like catalyst as described in any one of claims 1 to 3 in the activation of persulfate-degrading phenol wastewater.

10. The application according to claim 9, characterized in that, The pH of the phenol wastewater is 3-9.

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