Cobalt atom-derived carbon material Fenton catalyst and its preparation method and application

Abstract

The present invention discloses a cobalt-atom-derived carbon material Fenton-like catalyst, its preparation method, and application, relating to the technical field of Fenton-like catalysts. The present invention utilizes a pore confinement strategy to confine cobalt acetylacetonate within ZIF-8, a catalyst synthesized from zinc nitrate hexahydrate and dimethylimidazole, and then pyrolyzes the resulting Co-doped carbon material. This method retains the original ZIF-8 pore structure while introducing Co to form Co-N-C single-atom sites, significantly enhancing its performance in activating PMS and reducing the reaction energy for PMS activation, thereby promoting the decomposition of PMS to generate reactive oxygen species for efficient degradation of organic pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of Fenton-like catalysts, and in particular to a cobalt atom-derived carbon material Fenton-like catalyst and a preparation method and application thereof. Background Art

[0002] Metal-organic frameworks (MOFs) offer advantages such as high surface area, tunable pore structures, and abundant active sites, offering the potential to revolutionize existing advanced water treatment technologies. Their in situ generation of active species can effectively degrade pollutants, making MOFs highly promising for the removal of poly(propylene glycol) (PPCP) contaminants. However, due to the scarcity of water-stable MOFs and the insufficient active sites of some MOFs for peroxymonosulfate (PMS) activation, further manipulation is needed. MOF-derived carbon materials can maintain the original MOF pore structure while also increasing active sites for enhanced water stability. Among them, ZIF-8 (a zeolite-like imidazolate framework) exhibits excellent water stability and is easy to prepare. However, it still suffers from catalytic limitations, lacking active sites for activating oxidants such as PMS in the Fenton reaction. Further manipulation is needed to design novel structures for efficient water purification. Summary of the Invention

[0003] The present invention provides a cobalt atom-derived carbon material Fenton-like catalyst, its preparation method and application. Through the pore confinement strategy, the Co element is introduced into the ZIF-8 metal-organic framework and then pyrolyzed to prepare an efficient Fenton-like catalyst, thereby helping to activate PMS and enhance its Fenton-like performance.

[0004] In a first aspect, the present invention provides a method for preparing a cobalt atom-derived carbon material Fenton catalyst, comprising the following steps:

[0005] S1. Mix 2-methylimidazole and anhydrous methanol and disperse them uniformly by ultrasonication to prepare solution A;

[0006] S2, mixing zinc nitrate hexahydrate, cobalt acetylacetonate and anhydrous methanol and uniformly dispersing them by ultrasonication to prepare solution B;

[0007] S3, ultrasonically mixing solution A and solution B, reacting them, separating to obtain a precipitate, washing it with anhydrous methanol, and drying it to obtain a first product;

[0008] S4, ultrasonically dispersing the first product, 2-methylimidazole, and anhydrous methanol, and then placing them in an autoclave for reaction; then centrifuging to obtain a solid product, washing it, and drying it to obtain a second product;

[0009] S5. The second product is placed in a quartz boat and placed in a tube furnace for heating and calcining, and then naturally cooled to room temperature to obtain a catalyst.

[0010] Furthermore, the usage ratio of 2-methylimidazole to anhydrous methanol in S1 is 48 mmol:100 mL.

[0011] Furthermore, the usage ratio of zinc nitrate hexahydrate, cobalt (III) acetylacetonate and anhydrous methanol in S2 is 12 mmol:3.5 mmol:100 mL.

[0012] Furthermore, solution A and solution B in S3 were mixed and ultrasonicated for 10 minutes, and then reacted at 65° C. for 24 hours; the drying temperature was 60° C., and the drying time was 8 hours.

[0013] Furthermore, the usage ratio of the first product, 2-methylimidazole and anhydrous methanol in S4 is 1 g:1 g:50 mL.

[0014] Furthermore, the reaction temperature in the S4 autoclave was 140° C. and the reaction time was 4 h. After drying, the solid product was washed with anhydrous methanol and dried at 65° C. for 8 h.

[0015] Furthermore, the S5 tube furnace was heated to 1000 °C at a heating rate of 5 °C / min and kept at 1000 °C for 1 h.

[0016] In a second aspect, the present invention provides a Fenton catalyst of a cobalt atom-derived carbon material obtained by the above method.

[0017] In a third aspect, the present invention provides an application of the above-mentioned cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage, wherein the cobalt atom-derived carbon material Fenton catalyst and PMS are simultaneously added to sewage containing norfloxacin.

[0018] Furthermore, the mass ratio of the cobalt atom-derived carbon material Fenton catalyst to PMS is 2:15.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The present invention confines cobalt acetylacetonate in ZIF-8 synthesized by zinc nitrate hexahydrate and dimethylimidazole through a pore confinement strategy, and obtains a Co-doped carbon material by thermal decomposition. The original pore structure of ZIF-8 is retained and Co is introduced. Co is targeted through step S4 so that it is stably coordinated in the ZIF framework to form an active site, forming a Co-NC single-atom site, which greatly enhances its performance in activating PMS and reduces the reaction energy of activating PMS, thereby promoting the decomposition of PMS to generate reactive oxygen species and efficiently degrade organic pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Transmission electron microscopy image of CoSACs catalyst (left) and electron spectrometer surface scan of different elements (right);

[0022] Figure 2 The figure is a comparison of the diffraction peaks of the powder crystals of the preparation examples and comparative examples of the present invention and standard pure ZIF-8;

[0023] Figure 3 The nitrogen adsorption isotherms of the preparation examples, comparative examples and standard pure ZIF-8 in the present invention are shown;

[0024] Figure 4 This is a Fenton-like degradation curve of norfloxacin prepared in the examples and comparative examples of the present invention. DETAILED DESCRIPTION

[0025] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments, but the present invention is not limited thereto.

[0026] Preparation Example

[0027] S1. 2-Methylimidazole (3.94 g, 48 mmol) was mixed with 100 mL of anhydrous methanol by pore confinement strategy and ultrasonicated for 10 min to disperse uniformly to prepare solution A.

[0028] S2. Mix zinc nitrate hexahydrate (3.57 g, 12 mmol), cobalt (III) acetylacetonate (1.25 g, 3.5 mmol) and 100 mL of anhydrous methanol and ultrasonicate for 10 min to disperse them uniformly to prepare solution B.

[0029] S3. Solution A and solution B were mixed by ultrasonication for 10 min and then reacted at 65°C for 24 h. The resulting precipitate (gray-green) was separated and cleaned with anhydrous methanol, and dried at 60°C for 8 h to obtain the first product.

[0030] S4. Next, 1 g of the dried gray-green precipitate (i.e., the first product), 1 g of 2-methylimidazole, and 50 mL of anhydrous methanol were dispersed by ultrasonication for 10 minutes. The mixture was then placed in a 100 mL Teflon-lined autoclave and reacted at 140°C for 4 hours. The resulting precipitate (purple in color) was separated and washed several times with anhydrous methanol. The product was then dried at 65°C for 8 hours to obtain the second product.

[0031] S5. Place 300 mg of the dried purple powder in a quartz boat and place the boat in a tube furnace. Heat the tube furnace to 1000°C at a rate of 5°C / min and hold at 1000°C for 1 h. Allow the mixture to cool naturally to room temperature to yield the catalyst, designated CoSACs.

[0032] Comparative Example 1

[0033] S1. Mix 2-methylimidazole (3.94 g, 48 mmol) with 100 mL of anhydrous methanol and ultrasonicate for 10 min to disperse evenly to prepare solution A.

[0034] S2. Mix zinc nitrate hexahydrate (3.57 g, 12 mmol) and 100 mL of anhydrous methanol and ultrasonicate for 10 min to disperse uniformly to prepare solution B.

[0035] S3. Finally, solution A and solution B were mixed by ultrasonication for 10 minutes and then reacted at 65°C for 24 hours. The resulting precipitate (white) was separated and cleaned with anhydrous methanol. It was then dried at 60°C for 8 hours to obtain ZIF-8.

[0036] S4. Place 300 mg of dried ZIF-8 powder in a quartz boat and place the boat in a tube furnace. Heat the tube furnace to 1000°C at a rate of 5°C / min and maintain at 1000°C for 1 hour. Then cool naturally to room temperature to obtain the catalyst, designated ZIF-8-NC.

[0037] Comparative Example 2

[0038] S1. 2-Methylimidazole (3.94 g, 48 mmol) was mixed with 100 mL of anhydrous methanol by pore confinement strategy and ultrasonicated for 10 min to disperse uniformly to prepare solution A.

[0039] S2. Mix zinc nitrate hexahydrate (3.57 g, 12 mmol), cobalt (III) acetylacetonate (1.25 g, 3.5 mmol) and 100 mL of anhydrous methanol and ultrasonicate for 10 min to disperse them uniformly to prepare solution B.

[0040] S3. Solution A and solution B were mixed by ultrasonication for 10 min and then reacted at 65°C for 24 h. The resulting precipitate (gray-green) was separated and cleaned with anhydrous methanol, and dried at 60°C for 8 h to obtain the first product.

[0041] S4. Place the first product in a quartz boat, which is then placed in a tube furnace. The tube furnace is heated to 1000°C at a rate of 5°C / min and held at 1000°C for 1 hour. The mixture is then cooled naturally to room temperature to obtain the catalyst, designated Co@ZIF-8-NC.

[0042] The morphology of CoSACs was observed using a transmission electron microscope and the surface of CoSACs was scanned using an electron spectrometer. Figure 1 As shown, Figure 1 The uniform distribution of the elements was shown, demonstrating the successful introduction of Co active sites.

[0043] X-ray diffraction tests were performed on CoSACs, ZIF-8-NC, ZIF-8 and Co@ZIF-8-NC. Figure 2 As shown, Figure 2 It shows that most of the derived materials after carbonization are amorphous carbon and nitrogen. The characteristic peak of Co appears at more than 40 degrees in Co@ZIF-8-NC, proving that there is Co leakage.

[0044] Adsorption detection:

[0045] For each adsorption test, 100 mL of a 20 mg / L norfloxacin (NFC) solution was placed in a 100 mL wide-mouth glass vial. The solution was magnetically stirred at 600 rpm at room temperature (25°C). After the addition of 3.0 mg of CoSACs, the timer began. At the specified time points, 700 μL of the solution was sampled using a 1000 μL pipette. The solution was filtered through a 0.22 μm polyethersulfone membrane using a disposable syringe to remove solid particles and then transferred to a 2 mL screw-cap vial. Sampling times were 0, 1, 3, 5, 8, 10, 15, 30, 45, and 60 minutes (unit: min).

[0046] Repeat the above operation and replace CoSACs with ZIF-8-NC materials for adsorption test. The results are as follows Figure 3 shown.

[0047] pass Figure 3 The adsorption-desorption nitrogen isotherm test found that the pore structure of the carbonized derivative material did not completely collapse, which means that CoSACs can inherit the pore structure of the original ZIF-8.

[0048] Catalytic detection:

[0049] For each degradation experiment, 100 mL of a 20 mg / L NFC solution was placed in a 100 mL wide-mouth glass vial. The solution was magnetically stirred at 600 rpm at room temperature (25°C). 4.0 mg of carbonized material (CoSACs, ZIF-8-NC, and Co@ZIF-8-NC materials were each subjected to a separate degradation experiment) and 30 mg of PMS were added, and the timer began. (For a PMS blank experiment, only 30 mg of PMS was added.) At the specified time points, 700 μL of the solution was sampled using a 1000 μL pipette. The solution was filtered through a 0.22 μm polyethersulfone filter using a disposable syringe to remove solid particles and then transferred to a 2 mL screw-cap vial. Sampling was performed at 0, 1, 3, 5, 8, 10, 15, 30, 45, and 60 minutes (unit: min).

[0050] Before conducting the degradation experiment, 100 μL of 0.5 mol / L sodium thiosulfate solution needs to be added to a 2 mL screw-cap injection bottle in advance to allow sodium thiosulfate to undergo a redox reaction with unreacted PMS to avoid the influence of unreacted PMS on the experimental results.

[0051] Figure 4 The Fenton-like removal performance of CoSACs, ZIF-8-NC and Co@ZIF-8-NC for norfloxacin (NFC) is shown. In order to exclude the influence of adsorption, the adsorption test results are added to Figure 4 Within 30 minutes, the removal percentages ranked in the following order: CoSACs (92.6%) > Co@ZIF-8-NC (46.4%) > ZIF-8-NC (10.4%). This means that under the same experimental conditions, ZIF-8-NC was barely able to activate PMS for NFC degradation. In contrast, the incorporation of Co significantly boosted the catalyst's ability to activate PMS for pollutant degradation, resulting in the highest catalytic reaction rate.

[0052] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art may make changes and modifications to the present invention. If these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered to be within the scope of protection of the present invention.

Claims

1. Application of a cobalt atom-derived carbon material Fenton catalyst for norfloxacin in wastewater treatment, characterized by: A cobalt atom-derived carbon material-based Fenton catalyst and peroxymonosulfate are added simultaneously to wastewater containing norfloxacin; The preparation method of the cobalt atom-derived carbon material Fenton catalyst comprises the following steps: S1. Mix 2-methylimidazole and anhydrous methanol and disperse them uniformly by ultrasonication to prepare solution A; S2, mixing zinc nitrate hexahydrate, cobalt acetylacetonate and anhydrous methanol and uniformly dispersing them by ultrasonication to prepare solution B; S3, ultrasonically mixing solution A and solution B, reacting them, separating to obtain a precipitate, washing it with anhydrous methanol, and drying it to obtain a first product; S4. Ultrasonic dispersion of the first product, 2-methylimidazole, and anhydrous methanol was performed, followed by reaction in an autoclave; the reaction temperature in the autoclave was set at 140° C. for 4 hours; a solid product was obtained by centrifugation, cleaned, and dried to obtain a second product; S5. The second product is placed in a quartz boat and placed in a tube furnace for heating and calcining, and then naturally cooled to room temperature to obtain a catalyst.

2. The use of the cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage according to claim 1, characterized in that: The usage ratio of 2-methylimidazole to anhydrous methanol in S1 is 48 mmol:100 mL.

3. The use of the cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage according to claim 1, characterized in that: The usage ratio of zinc nitrate hexahydrate, cobalt acetylacetonate and anhydrous methanol in S2 is 12 mmol:3.5 mmol:100 mL.

4. The use of the cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage according to claim 1, characterized in that: In S3, solution A and solution B were mixed and ultrasonicated for 10 minutes, and then reacted at 65°C for 24 hours; the drying temperature was 60°C and the drying time was 8 hours.

5. The use of the cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage according to claim 1, characterized in that: The usage ratio of the first product, 2-methylimidazole and anhydrous methanol in S4 is 1 g:1 g:50 mL.

6. Use of the cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage according to claim 1, characterized in that: After drying, the solid product was washed with anhydrous methanol and dried at 65 °C for 8 h.

7. Use of the cobalt atom-derived carbon material Fenton catalyst in treating norfloxacin in sewage according to claim 1, characterized in that: The S5 tube furnace was heated to 1000 °C at a heating rate of 5 °C / min and kept at 1000 °C for 1 h.

8. Use of the cobalt atom-derived carbon material Fenton catalyst for treating norfloxacin in sewage according to claim 1, characterized in that: The mass ratio of the cobalt atom-derived carbon material Fenton catalyst to peroxymonosulfate is 2:15.

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