COF-loaded Fe3O4-MnO2 catalyst as well as preparation method and application thereof
By loading Fe3O4-MnO2 catalyst on COF, the problem of easy agglomeration of the catalyst is solved, the activation efficiency of PMS and the degradation effect of TC are improved, and efficient TC degradation is achieved.
Patent Information
- Application Number
- CN202510548048.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-28
- Publication Date
- 2025-08-01
AI Technical Summary
The existing Fe3O4-MnO2 bimetallic catalysts are prone to agglomeration in solution, have poor dispersion and stability, limit their catalytic activity, and are not efficient when activated permonosulfate (PMS), making it difficult to effectively degrade tetracycline (TC).
The Fe3O4-MnO2 composite was prepared by hydrothermal synthesis by using a covalent organic framework (COF)-supported Fe3O4-MnO2 catalyst, and the Fe3O4-MnO2 composite was supported by hydrothermal synthesis, and the Fe3O4-MnO2@COF composite was formed, and the dispersion and stability were improved by using the porous structure of COF and the high specific surface area, and the catalytic activity was enhanced.
The Fe3O4-MnO2 catalyst is uniformly distributed in COF pores, which improves the activation efficiency of PMS, significantly improves the degradation efficiency of TC, reaching 98.5%, and improves the dispersion and stability of the catalyst.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalytic addition, and particularly relates to a COF-supported Fe3O4-MnO2 catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] As a typical broad-spectrum antibiotic, tetracycline (TC) has been widely used in the medical and livestock industries due to its broad-spectrum antibacterial properties, economic efficiency, and other advantages. In the water environment, TC can disrupt the balance of the aquatic ecosystem by inhibiting the microbial community structure, inducing the spread of drug-resistant genes, etc., and threaten human health through food chain enrichment. Therefore, it is urgent to develop an efficient advanced treatment technology.
[0003] In recent years, advanced oxidation processes based on sulfate radicals (SO4 2- ) have shown significant advantages in the treatment of refractory organic pollutants due to their strong oxidation ability, good environmental adaptability, and high degradation rate. The core of this process lies in the efficient activation of peroxymonosulfate (PMS) to generate reactive oxygen species. As a common iron-based oxide containing abundant Fe 2+ , Fe3O4 can improve the rate of catalyzing PMS to produce SO4 2- . However, the surface Fe 2+ is easily oxidized to Fe 3+ , resulting in the passivation of active sites. Introducing other transition metals to construct a bimetallic structure with Fe3O4 can promote the cyclic regeneration of Fe 2+ / Fe 3+ . At the same time, the electron transfer efficiency and the activation efficiency of PMS can be improved through the synergistic effect between metals, enhancing the oxidation ability of the reaction. In recent years, due to its large specific surface area, low cost, high activity, and strong oxidizing property, MnO2 has been widely used in water treatment technology. Therefore, nano-MnO2 can be compounded with Fe3O4 to form a bimetallic catalyst.
[0004] Although the Fe3O4-MnO2 bimetallic catalyst shows potential catalytic advantages, it is easy to agglomerate in solution, with poor dispersibility and stability, which may limit its catalytic activity. As a new type of porous organic crystal, covalent organic framework (COF) shows unique advantages in the field of catalyst carriers due to its high specific surface area, adjustable pore structure, and excellent chemical stability, especially the regular pore channels constructed by its strong covalent bonds (such as C=N, C=C, C-N, etc.). At present, the application of COF materials mainly focuses on gas adsorption and storage, photocatalysis, and pollutant adsorption, etc., and the research on PMS activation is relatively limited. Therefore, a new type of catalyst is needed to activate PMS to degrade TC. Summary of the Invention
[0005] The object of the present invention is to provide a preparation method of a COF-supported Fe3O4-MnO2 catalyst to solve the above technical problems existing in the prior art.
[0006] The second object of the present invention also lies in providing a COF-supported Fe3O4-MnO2 catalyst.
[0007] The second object of the present invention also lies in providing an application of a COF-supported Fe3O4-MnO2 catalyst.
[0008] To achieve the above object, a preparation method of a COF-supported Fe3O4-MnO2 catalyst of the present invention adopts the following technical solution: A preparation method of a COF-supported Fe3O4-MnO2 catalyst includes the following steps:
[0009] 1) Prepare a Fe3O4-MnO2 solid composite by a hydrothermal synthesis method;
[0010] 2) Add the Fe3O4-MnO2 solid composite, TPA, and TAPB in step 1) into DMSO, perform ultrasonic treatment, and add HAC during the ultrasonic process; during this process, the amino group of TAPB and the aldehyde group of TPA form an imine-based COF through a Schiff base condensation reaction, and then Fe3O4-MnO2 is successfully loaded onto the imine-based COF to form a Fe3O4-MnO2@COF product;
[0011] 3) Centrifuge and separate the Fe3O4-MnO2@COF product in step 2), and collect the particulate solid.
[0012] After washing and drying, a Fe3O4-MnO2@COF catalyst powder is obtained.
[0013] In step 1), the Fe3O4-MnO2 solid composite is achieved through the following steps:
[0014] a) Dissolve FeCl3·6H2O in ethylene glycol and stir until completely dissolved;
[0015] b) Add NaAc·3H2O to the above solution and stir until homogeneous;
[0016] c) Transfer the solution obtained in step b) to a hydrothermal synthesis reaction kettle, cool after the reaction, filter out the product, wash and dry to obtain magnetic Fe3O4 particles.
[0017] d) Prepare a KMnO4 solution and a MnCl2 solution and mix them together to obtain a mixed solution;
[0018] e) Add the magnetic Fe3O4 particles in step c) into the mixed solution in step d), then transfer it to a hydrothermal synthesis reactor. After the reaction, cool it, filter out the product, wash and dry it to obtain
[0019] the Fe3O4-MnO2 solid composite.
[0020] In step c), the reaction temperature is 200 °C and the reaction time is 8 h.
[0021] In step d), the mixed solution is magnetically stirred at 35 °C for 30 min.
[0022] In step e), after adding the magnetic Fe3O4 particles, ultrasonically treat the mixed solution for 15 min, and then transfer it to a hydrothermal synthesis reactor.
[0023] In step e), the reaction conditions in the hydrothermal synthesis reactor are 150 °C and the reaction time is 30 min.
[0024] In step 2), the ultrasonication time is 15 min.
[0025] In step 3), the collected granular solid is successively washed alternately with methanol and tetrahydrofuran, and then dried.
[0026] A COF-supported Fe3O4-MnO2 catalyst is prepared by the above-mentioned preparation method of the COF-supported Fe3O4-MnO2 catalyst.
[0027] An application of a COF-supported Fe3O4-MnO2 catalyst in the degradation of TC.
[0028] Advantages of the present invention: In the COF-supported Fe3O4-MnO2 catalyst obtained in the present invention, it can be seen that the Fe3O4 / MnO2 bimetallic oxide is uniformly loaded into the pores of the porous network-like COF, and the corresponding element distribution is uniform. Moreover, it can well activate PMS to degrade TC. Description of the Drawings
[0029] Figure 1 are SEM images of the Fe3O4, MnO2, Fe3O4 / MnO2, and Fe3O4 / MnO2@COF composite catalyst powders of the present invention;
[0030] Figure 2 is the EDS analysis diagram of the Fe3O4 / MnO2@COF composite catalyst powder;
[0031] Figure 3 is the XRD analysis diagram of the Fe3O4 / MnO2@COF composite catalyst powder;
[0032] Figure 4 The influence on the degradation efficiency of TC under different systems and kinetic analysis Specific implementation method
[0033] Prepare the Fe3O4 / MnO2 bimetallic catalyst by hydrothermal synthesis method: Weigh 2.08 g of FeCl3·6H2O and dissolve it in 100 ml of ethylene glycol, stir until completely dissolved, weigh 5.24 g of NaAc·3H2O and add it to the above solution, magnetically stir at room temperature for 1 h until homogeneous. Transfer the stirred solution to a hydrothermal synthesis reaction kettle with a polytetrafluoroethylene liner, react at 200 °C for 8 h, then cool to room temperature. Filter out the obtained product and wash it alternately three times with deionized water and absolute ethanol. Finally, place it in a vacuum drying oven at 65 °C and dry for 5 h to obtain magnetic Fe3O4 particles. Prepare a KMnO4 solution with a concentration of 0.04 mol / L and a MnCl2 solution with a concentration of 0.06 mol / L. Take 36 ml of the KMnO4 solution and 39 ml of MnCl2·4H2O and mix them. Magnetically stir the mixed solution at 35 °C for 30 min. Add 0.10 g of the above-prepared Fe3O4 finished product, ultrasonically treat the mixed solution for 15 min, then transfer it to a hydrothermal synthesis reaction kettle with a polytetrafluoroethylene liner, and react at 150 °C for 30 min. Wait for it to cool naturally to room temperature, filter out the product, and the washing and drying methods are the same as above. That is, a magnetic Fe3O4 / MnO2 solid composite is obtained.
[0034] Form the Fe3O4 / MnO2@COF composite material by in-situ growth method: Add 0.35 g of the Fe3O4 / MnO2 solid composite, 0.13 g of TPA, and 0.22 g of TAPB to 120 ml of DMSO, ultrasonically treat for 15 min, and add 4 ml of 17.5 M HAC during the ultrasonic treatment. During this process, the amino group of TAPB and the aldehyde group of TPA form an imine-based COF through a Schiff base condensation reaction. Finally, Fe3O4 / MnO2 is successfully loaded onto the imine-based COF to form the Fe3O4 / MnO2@COF composite material. Centrifuge and collect the particulate solid of the obtained product at 4000 r / min, wash it alternately three times with methanol and tetrahydrofuran, and dry it in a vacuum drying oven for 5 h. The Fe3O4 / MnO2@COF composite catalyst powder can be obtained.
[0035] Perform SEM (scanning electron microscope) observation on Fe3O4 and MnO2 used in the above process, and the Fe3O4 / MnO2 and the finally obtained Fe3O4 / MnO2@COF composite catalyst powder in the above steps. The results are as Figure 1As shown. It can be found from (a) that Fe3O4 is in the shape of microspheres with an uneven surface. In figure (b), MnO2 is a flower-like sphere composed of many nanosheets, and its large specific surface area is conducive to the attachment of Fe3O4. Figure (c) shows that Fe3O4 particles have been evenly dispersed on the surface of the flower-like MnO2. The diameter of Fe3O4 / MnO2 is about 35 nm, and the aggregation phenomenon is obvious. It can be seen from figure (d) that Fe3O4 / MnO2 is loaded into the pores of COF. The COF layer has a porous network structure, and the diameter of Fe3O4 / MnO2@COF is about 50 nm, and the aggregation phenomenon is significantly improved.
[0036] EDS analysis was carried out on the obtained Fe3O4 / MnO2@COF composite catalyst powder, and the elemental composition of the Fe3O4 / MnO2@COF composite material was identified by EDS. As Figure 2 shown, the main elements of this composite catalyst are C, N, O, Fe, and Mn, and their distribution is relatively uniform, indicating that the composite effect of the catalyst is good, and it can further prove the successful preparation of the catalyst.
[0037] XRD analysis was carried out on the obtained Fe3O4 / MnO2@COF composite catalyst powder. As Figure 3 shown, obvious characteristic peaks of Fe3O4 appeared at five angles of 2θ = 30.1°, 35.3°, 43°, 56.9° and 62.6°, corresponding to the (220), (311), (400), (511), (440) five crystal planes in the magnetite standard card (85-1436) respectively, indicating that the prepared Fe3O4 has a good crystal form. Obvious characteristic peaks of MnO2 appeared at four angles of 2θ = 22.1°, 37.1°, 42.6° and 56.5°, corresponding to the (120), (131), (300) and (160) four crystal planes in the manganese dioxide standard card (14-0644) respectively, indicating that the prepared MnO2 has a good crystal form. A decrease in diffraction intensity was observed in the XRD pattern of Fe3O4 / MnO2@COF, because the addition of COF weakened the X-ray diffraction intensity of other substances. At the same time, the positions of the diffraction peaks in the composite spectrum remained basically unchanged and obvious diffraction peaks appeared at 37.1°, 42.5° and 55.9°, indicating the successful synthesis of Fe3O4 / MnO2@COF and the material retained the crystal structures of Fe3O4 and MnO2.
[0038] To investigate the efficiency of the composite catalyst in activating PMS for the degradation of TC, five catalytic systems were established, namely, those with the addition of PMS, Fe3O4 / MnO2, Fe3O4 / MnO2 + PMS, Fe3O4 / MnO2@COF, and Fe3O4 / MnO2@COF + PMS. The initial conditions were as follows: pH = 5, the dosage of the catalyst was 200 mg / L, the initial concentration of TC was 30 mg / L, the dosage of PMS was 0.07 g / L, and the reaction time was 60 min for all cases. The mass ratio of Fe3O4 / MnO2:COF was 1:1. The results are as Figure 4 shown. As Figure 4 (a) shows, PMS alone can only oxidize a part of TC, and the oxidation effect is limited. The efficiency of removing TC by Fe3O4 / MnO2 alone is the worst, only 27.5%, which is because Fe3O4 / MnO2 alone can only play an adsorption role. After adding PMS, the efficiency of Fe3O4 / MnO2 in removing TC is increased to 85%, which indicates that after adding PMS, the metal elements in the bimetallic catalyst activate PMS to generate active groups, and the synergistic effect between iron and manganese will also promote the activation of PMS. Relevant research shows that E0(Fe 3+ / Fe 2+ ) = 0.77 V and E0(Mn 4+ / Mn 3+ ) = 0.15 V. According to the principle of standard reduction potential, the reduction potential of Mn 3+ is relatively low. Therefore, Mn 3+ can act as a reducing agent to reduce Fe 3+ to Fe 2+ (see Equations 1 - 4), thereby generating free radicals more efficiently and further degrading organic pollutants. When Fe3O4 / MnO2 is loaded onto COF and PMS is added, the efficiency of the system in degrading TC can reach 98.5%, which indicates that the high surface area and porous structure of COF can adsorb TC and PMS, enhancing their reactivity. In addition, the organic framework of COF can not only reduce the agglomeration of Fe3O4 / MnO2 but also promote the electron transfer between Fe3O4 and MnO2, improving the activity of these two metal catalysts, synergistically activating PMS, and generating more SO4 2- and ·OH, enhancing the overall effect of the reaction.
[0039] Mn 3+ + Fe 3+ → Mn 4+ + Fe 2+ (1)
[0040] Fe 2+ + HSO5 - → Fe 3+ + SO4 - + OH -(2)
[0041] Fe 2+ + HSO5 - →Fe 3+ +·OH + SO4 2- (3)
[0042] Mn 4+ + HSO5 - →Mn 3+ + SO4 2- +·OH (4)
[0043] From Figure 4 (b), it can be seen that the degradation rate constant of the Fe3O4 / MnO2 + PMS system is 0.0338 min -1 . The degradation rate constant of the Fe3O4 / MnO2@COF + PMS system is 0.0666 min -1 . Therefore, Fe3O4 / MnO2@COF can efficiently activate PMS to degrade TC.
Claims
1. A preparation method of a COF-supported Fe3O4-MnO2 catalyst, characterized in that, It includes the following steps: 1) Prepare the Fe3O4-MnO2 solid composite by hydrothermal synthesis method; 2) Add the Fe3O4-MnO2 solid composite, TPA and TAPB in step 1) into DMSO, perform ultrasonic treatment, and add HAC during the ultrasonic process; during this process, the amino group of TAPB and the aldehyde group of TPA form an imine group COF through Schiff base condensation reaction, and then Fe3O4-MnO2 is successfully loaded onto the imine group COF to form the Fe3O4-MnO2@COF product; 3) Centrifuge and separate the Fe3O4-MnO2@COF product in step 2), collect the particulate solid, wash and dry it to obtain the Fe3O4-MnO2@COF catalyst powder.
2. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 1, characterized in that: In step 1), the Fe3O4-MnO2 solid composite is achieved through the following steps a) Dissolve FeCl3·6H2O in ethylene glycol and stir until completely dissolved; b) Add NaAc·3H2O into the above solution and stir until homogeneous; c) Transfer the solution obtained in step b) into a hydrothermal synthesis reactor, cool after the reaction, filter out the product, wash and dry it to obtain magnetic Fe3O4 particles. d) Prepare KMnO4 solution and MnCl2 solution and mix them together to obtain a mixed solution; e) Add the magnetic Fe3O4 particles in step c) into the mixed solution in step d), then transfer it into a hydrothermal synthesis reactor, cool after the reaction, filter out the product, wash and dry it to obtain the Fe3O4-MnO2 solid composite.
3. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 2, wherein: In step c), the reaction temperature is 200 °C and the reaction time is 8 h.
4. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 2, characterized in that: In step d), the mixed solution is magnetically stirred at 35 °C for 30 min.
5. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 2, wherein: In step e), after adding the magnetic Fe3O4 particles, ultrasonically treat the mixed solution for 15 min and then transfer it into a hydrothermal synthesis reactor.
6. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 2, characterized in that: In step e), the reaction conditions in the hydrothermal synthesis reactor are 150 °C and the reaction time is 30 min.
7. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 1, characterized in that: In step 2), the ultrasonic treatment time is 15 min.
8. The preparation method of the COF-supported Fe3O4-MnO2 catalyst according to claim 1, characterized in that: In step 3), the collected particulate solid is washed alternately with methanol and tetrahydrofuran in sequence and then dried.
9. A COF-supported Fe3O4-MnO2 catalyst, characterized in that: It is prepared by using the preparation method of the COF-supported Fe3O4-MnO2 catalyst described in claim 1.
10. Application of a COF-supported Fe3O4-MnO2 catalyst, characterized in that: Application in the degradation of tetracycline.