A composite photocatalyst doped with a metal organic framework and a covalent organic framework and a preparation method and application thereof

Abstract

The application discloses a kind of metal organic framework and covalent organic framework doped composite photocatalyst and its preparation method and application, belong to the technical field of heterogeneous fenton catalysis.The present application uses polyethylene imine modified 3,3'-diamino diphenyl dicarboxylic acid and iron trichloride hexahydrate as iron-based metal organic framework material building unit, 2,4,6-tris (4-formylphenyl) -1,3,5-triazine and p-phenylenediamine as covalent organic framework monomer, to build heterojunction PP-PEI / MOF@COF composite photocatalyst.The composite photocatalyst is wider in light response range, has good absorbance in the visible light region, is more likely to excite to generate photo-generated electrons, and has better photocatalytic performance.

Description

Technical Field

[0001] This invention belongs to the field of multiphase Fenton catalysis technology, and particularly relates to a composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks, its preparation method and application. Background Technology

[0002] After tetracycline administration, only a small portion of the drug is digested and absorbed during the body's metabolism; the majority of the unabsorbed drug is excreted as the original compound or metabolites and enters the environment. Tetracycline in the environment can cause bioaccumulation and biomagnification in the food chain, posing a serious threat to human and animal health and ecological security. Furthermore, prolonged exposure to tetracycline antibiotics in the natural environment may induce bacteria to transform into antibiotic-resistant bacteria, exacerbating the spread of antibiotic resistance. Therefore, removing large and even trace amounts of antibiotics from the aquatic environment has significant scientific and environmental implications.

[0003] Photocatalytic degradation oxidation technology is an advanced oxidation technology that is green and environmentally friendly, and has a good degradation effect on antibiotics in the aquatic environment. Metal-organic frameworks (MOFs) exhibit excellent catalytic performance when photoexcited, as the generated photoelectrons can be transferred to metal clusters through organic ligands. Iron-based MOFs contain a large number of iron-oxygen clusters and can directly utilize visible light for catalysis, showing broad application prospects in photocatalysis. However, due to problems such as high electron-hole recombination rates, low visible light utilization, and low utilization of active species, the purification effect of conventional iron-based MOFs is unsatisfactory. Therefore, designing and preparing catalysts with a wide light absorption range, low band gap energy, and high visible light photocatalytic activity is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks (PP-PEI / MOF@COF), along with its preparation method and applications.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a composite photocatalyst doped with a metal-organic framework and a covalent organic framework includes the following steps: Using 3,3'-diaminobiphenyl dicarboxylic acid as an organic ligand, ferric chloride hexahydrate as a metal ion, and N,N-dimethylacetamide as a reaction solution, the first reaction was carried out to obtain NH2-UIO-67-Fe; A second reaction was carried out using NH2-UIO-67-Fe and polyethyleneimine dilution as reaction substrates and methanol as reaction solution to obtain PEI / MOF. In this process, polyethyleneimine (PEI) was modified on the surface of NH2-UIO-67-Fe. Using PEI / MOF as the reaction substrate, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and p-phenylenediamine as covalent organic framework PP-COF monomers, o-dichlorobenzene and n-butanol as the reaction solution, and acetic acid solution as the regulator, a third reaction (aldehyde-amine condensation reaction) was carried out to obtain PP-PEI / MOF@COF composite material.

[0006] Furthermore, the molar ratio of 3,3'-diaminobiphenyl dicarboxylic acid and ferric chloride hexahydrate is 1:1; The ratio of NH2-UIO-67-Fe, polyethyleneimine diluent, and methanol is 30 mg: 0.1 mL: 15 mL. The mass ratio of PEI / MOF, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine, and p-phenylenediamine is 20 mg: 40 mg: 16.6 mg. The volume ratio of o-dichlorobenzene to n-butanol is 1:1.

[0007] Furthermore, the concentration of the acetic acid solution is 6 mol / L.

[0008] Furthermore, the first reaction was carried out at 130°C for 24 hours; The second reaction was carried out at 25°C for 12 hours. The third reaction was carried out at 120°C for 72 hours.

[0009] The present invention also provides a composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks prepared by the above preparation method.

[0010] This invention also provides an application of a composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks for the efficient photocatalytic degradation of tetracycline under visible light.

[0011] Furthermore, the concentration of tetracycline is 0.02 g / L, and the concentration of the composite photocatalyst doped with the metal-organic framework and the covalent organic framework is 0.02-0.1 g / L.

[0012] Furthermore, in the process of efficient photocatalytic degradation of tetracycline under visible light, the adsorption equilibrium time was 30 min and the degradation reaction time was 30 min.

[0013] Compared with the prior art, the present invention has the following advantages and technical effects: This invention synthesizes PP-PEI / MOF@COF composite photocatalysts by solvothermal synthesis of NH2-UIO-67-Fe, polyethyleneimine (PEI), and PP-COF (triazine covalent organic framework material). The synthesized PP-PEI / MOF@COF composite photocatalysts have a wider light response range, good absorbance in the visible light region, and are more easily excited to generate photogenerated electrons.

[0014] The composite photocatalyst prepared by this invention has a faster rate of photogenerated electron excitation and transfer, and superior photocatalytic performance.

[0015] The composite photocatalyst prepared by this invention has a small band gap, which is beneficial for the separation of photogenerated electrons and holes. It can also absorb and utilize visible light, requires less energy for photocatalytic excitation, has better photocatalytic performance, and has a high photocatalytic degradation effect on antibiotic substances in wastewater. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 Transmission electron microscopy image of the PP-PEI / MOF@COF composite photocatalyst prepared in Example 1; Figure 2 The diffraction patterns of the NH2-UIO-67-Fe, PEI / MOF and PP-PEI / MOF@COF composite photocatalysts in Example 1 are shown. Figure 3 Infrared spectra of the NH2-UIO-67-Fe, PEI / MOF and PP-PEI / MOF@COF composite photocatalysts in Example 1; Figure 4 Electrochemical impedance spectroscopy of the NH2-UIO-67-Fe, PEI / MOF and PP-PEI / MOF@COF composite photocatalysts in Example 1; Figure 5 The graph shows the cycling current curves of the NH2-UIO-67-Fe, PEI / MOF, and PP-PEI / MOF@COF composite photocatalysts in Example 1. Figure 6 The (Ahv) of the PP-PEI / MOF@COF composite photocatalyst in Example 1. 2 Plot the hv graph; Figure 7 The degradation of tetracycline by different concentrations of PP-PEI / MOF@COF composite photocatalyst in Example 1 is shown in the figure. Figure 8 This is a graph showing the degradation of tetracycline by different catalysts. Detailed Implementation

[0017] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0019] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0020] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0021] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0022] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0023] All raw materials used in this invention were purchased from the market.

[0024] This invention provides a composite photocatalyst based on a metal-organic framework and a covalent organic framework (PP-PEI / MOF@COF). Polyethyleneimine-modified 3,3'-diaminobiphenyl dicarboxylic acid and ferric chloride hexahydrate are used as iron-based metal-organic framework building blocks, while 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and p-phenylenediamine are used as covalent organic framework monomers to construct a heterojunction PP-PEI / MOF@COF composite material. The preparation method includes the following steps: Step 1, preparing NH2-UIO-67-Fe material using a one-pot method; Step 2, modifying the NH2-UIO-67-Fe surface with polyethyleneimine (PEI) by stirring at room temperature; Step 3, preparing the PP-PEI / MOF@COF composite material by aldehyde-amine condensation. Furthermore, this invention also discloses the application of this material in the adsorption and degradation of tetracycline. This invention employs metal-organic frameworks and covalent organic frameworks for doping to maximize the advantages of adsorption and degradation. It utilizes the synergistic effect of the electron-donating group -NH2 in the iron-based metal-organic framework and the triazine structure with electron-deficient properties of the covalent organic framework to promote the separation of photogenerated electrons and holes, thereby achieving the purpose of synergistic adsorption and degradation.

[0025] The specific technical solution is as follows: A method for preparing a composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks (PP-PEI / MOF@COF), comprising the following steps: Step 1: The reaction was carried out using 3,3'-diaminobiphenyl dicarboxylic acid as an organic ligand, ferric chloride hexahydrate as a metal ion, and N,N-dimethylacetamide as a reaction solution. The reaction product was washed with anhydrous ethanol and N,N-dimethylacetamide and dried to obtain NH2-UIO-67-Fe. Step 2: Using NH2-UIO-67-Fe and diluted polyethyleneimine (PEI) as the reaction substrate and methanol as the reaction solution, the reaction product was washed with methanol to obtain PEI / MOF; Step 3: Using PEI / MOF as the reaction substrate, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and p-phenylenediamine as covalent organic framework PP-COF monomers, o-dichlorobenzene and n-butanol as the reaction solution, and acetic acid solution as the regulator, the reaction was carried out. The reaction product was washed with ethanol, acetone and tetrahydrofuran and dried to obtain the PP-PEI / MOF@COF composite photocatalyst.

[0026] This invention is based on the aldehyde-amine condensation reaction, using a solvothermal synthesis method to synthesize a PP-PEI / MOF@COF composite photocatalyst from NH2-UIO-67-Fe, polyethyleneimine (PEI), and PP-COF. The amino-rich PEI coats NH2-UIO-67-Fe, providing more binding sites for PP-COF and facilitating the formation of a dense, uniform, and highly crystalline covalent organic framework (COF) shell. Compared to single metal-organic frameworks (MOFs), the composite material exhibits better stability due to the inclusion of chemically more stable PP-COF.

[0027] In step one of the following embodiments of the present invention, the molar ratio of 3,3'-diaminobiphenyl dicarboxylic acid and ferric chloride hexahydrate is 1:1; the amount of N,N-dimethylacetamide added is 40 mL. The reaction temperature is 130 °C, and the reaction time is 24 h.

[0028] This invention synthesizes NH2-UIO-67-Fe from 3,3'-diaminobiphenyl dicarboxylic acid and ferric chloride hexahydrate using a solvothermal synthesis method. The amino group and biphenyl ligand in the structure are beneficial to the excitation and transfer of photogenerated electrons, which can enhance the catalytic activity of the photocatalyst.

[0029] In step two of the following embodiments of the present invention, the amount of polyethyleneimine (PEI) diluent added is 100 μL, and the volume of methanol is 15 mL. The reaction temperature is 25 °C, and the reaction time is 12 h. The ratio of NH2-UIO-67-Fe, polyethyleneimine diluent, and methanol is 30 mg: 0.1 mL: 15 mL.

[0030] The reaction temperature of this invention is 25℃. PEI / MOF is synthesized from NH2-UIO-67-Fe and PEI. The preparation method is simple, and the amino-rich polymer PEI can protect the amino sites in NH2-UIO-67-Fe to ensure photocatalytic activity, and also provide binding sites for PP-COF.

[0031] In step three of the following embodiments of the present invention, the mass ratio of PEI / MOF, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine, and p-phenylenediamine is 20 mg:40 mg:16.6 mg; the volume ratio of o-dichlorobenzene to n-butanol is 1:1; and the volume ratio of p-phenylenediamine to acetic acid solution is 16.6 mg:0.6 mL. The concentration of the acetic acid solution is 6 mol / L. The reaction is carried out at 120 °C for 72 h.

[0032] This invention synthesizes a PP-PEI / MOF@COF composite photocatalyst from PP / MOF and PP-COF using a solvothermal synthesis method. The covalent bonding between the two materials is achieved through an aldehyde-amine condensation reaction between the aldehyde group and the amino group on the surface of the PEI / MOF material, resulting in a more stable and robust bond than traditional coordination bonds, electrostatic interactions, and van der Waals forces. It exhibits excellent light absorption performance in the 350-600 nm range, with a band gap of 2.40 eV; its impedance radius is smaller than that of a single NH2-UIO-67-Fe material, and its surface electron density is higher, which is beneficial for electron transfer during the photocatalytic process.

[0033] The above-described preparation method can be used to prepare composite photocatalysts doped with metal-organic frameworks and covalent organic frameworks. The components used in the synthesis of this composite photocatalyst include NH2-UIO-67-Fe, PEI, and PP-COF.

[0034] The composite photocatalyst doped with the metal-organic framework and covalent organic framework can be applied to antibiotic wastewater treatment, efficiently photocatalytically degrading tetracycline under visible light. During the efficient photocatalytic degradation of tetracycline under visible light, the concentration of tetracycline is 0.02 g / L, and the concentration of the composite photocatalyst doped with the metal-organic framework and covalent organic framework is 0.02-0.1 g / L. The adsorption equilibrium time is 30 min, and the degradation reaction time is 30 min.

[0035] The technical solution of the present invention will be further illustrated by the following embodiments.

[0036] Example 1 A method for preparing composite photocatalysts doped with metal-organic frameworks and covalent organic frameworks using a one-pot method and aldehyde-amine condensation, comprising the following steps: (1) Using 3,3'-diaminobiphenyl dicarboxylic acid as the organic ligand and ferric chloride hexahydrate as the metal ion, NH2-UIO-67-Fe was prepared by a one-pot method. The specific method is as follows: 68.00 mg of 3,3'-diaminobiphenyl dicarboxylic acid (0.25 mmol) and 67.60 mg of ferric chloride hexahydrate (0.25 mmol) were weighed into a 50 mL round-bottom flask, 10 mL of N,N-dimethylacetamide was added, and the mixture was sonicated for 15 min. Then, 1 mL of 6 mol / L acetic acid was added, and the mixture was heated and stirred at 130 °C for 24 h. The product was washed twice with N,N-dimethylacetamide and ethanol to remove the reaction precursor, and then dried under vacuum at 50 °C overnight to obtain NH2-UIO-67-Fe. (2) Using NH2-UIO-67-Fe and PEI dilution as reaction substrates, PEI / MOF was prepared by stirring at room temperature. The specific method is as follows: 30.00 mg of NH2-UIO-67-Fe was accurately weighed into a 25 mL Erlenmeyer flask, 15 mL of methanol was added, and the mixture was sonicated for 30 s. Then, 100 μL of PEI dilution was added to the Erlenmeyer flask, and the mixture was stirred at 400 r / min and room temperature (25 °C) for 12 h. After the reaction was completed, the mixture was washed twice with methanol to obtain PEI / MOF. (3) Using PEI / MOF as the reaction substrate, and 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and p-phenylenediamine as PP-COF monomers, PP-PEI / MOF@COF was prepared by aldehyde-amine condensation. The specific method is as follows: 20 mg of PEI / MOF, 40.00 mg of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine, 2.0 mL of o-dichlorobenzene, and 2.0 mL of [unclear text - possibly a conical flask] were added to a 25 mL Erlenmeyer flask. n-Butanol was added and stirred at room temperature for 3 hours. The resulting reaction solution and 16.60 mg of p-phenylenediamine were placed in a 100 mL Shrek tube, and 0.6 mL of 6 mol / L acetic acid was added under ultrasonic conditions. The mixture was degassed three times by freezing and then heated in an oil bath at 120 °C for 72 hours. After the reaction was completed, the mixture was washed sequentially with ethanol, acetone, and tetrahydrofuran, and then dried under vacuum at 70 °C overnight. The resulting PP-PEI / MOF@COF composite photocatalyst was stored in a dry container for later use.

[0037] Characterization of PP-PEI / MOF@COF composite photocatalyst I. Transmission Electron Microscopy Observation: The structure and microstructure of the photocatalytic material were investigated using a SU8010 field emission scanning electron microscope (SEM) from Tianmei (China) Scientific Instruments Co., Ltd., with an accelerating voltage of 10kV.

[0038] Figure 1 The image shown is a transmission electron microscope (TEM) image of the PP-PEI / MOF@COF composite photocatalyst prepared in Example 1. Figure 1 It can be seen that the PP-PEI / MOF@COF composite photocatalyst has an amorphous sheet-like structure modified on the surface of NH2-UIO-67-Fe.

[0039] II. XRD Analysis: The crystal structure of the composite photocatalytic material prepared in Example 1 was tested using an X-ray diffractometer equipped with CuKα radiation. The test range was 5°-80° and the scanning speed was 5° / min.

[0040] Figure 2The diffraction patterns of the NH2-UIO-67-Fe, PEI / MOF, and PP-PEI / MOF@COF composite photocatalysts in Example 1 are shown. The characteristic peaks of NH2-UIO-67-Fe are located at 6.23° (111) and 9.91° (022), while other peaks at 12.61°, 13.30°, and 19.05° correspond to the (113), (004), and (115) crystal planes, respectively. Figure 2 It can be seen that with the modification of PEI and COF, the XRD peaks of PEI / MOF and PP-PEI / MOF@COF gradually shift and weaken, and the crystallinity of the material decreases.

[0041] III. Infrared Analysis: The functional groups and chemical bonds on the surface of the composite photocatalytic material were detected using Fourier transform infrared spectroscopy, with a testing range of 500-4000 cm⁻¹. -1 The molecular structures of NH2-UIO-67-Fe, PEI / MOF, and PP-PEI / MOF@COF were characterized using Fourier transform infrared spectroscopy. The results are as follows: Figure 3 As shown.

[0042] from Figure 3 As can be seen, the absorption regions of the three materials are mainly in the range of 530-700 cm⁻¹. -1 725-925cm -1 1100-1700cm -1 and 2800-3400cm -1 There are differences within the range. 530-700cm -1 The absorption peaks within the PP-PEI / MOF are attributed to the Fe-O vibration. The characteristic peaks in NH2-UIO-67-Fe and PEI / MOF are prominent, indicating that Fe is coordinated with the ligand and is not affected by PEI modification. The absorption peaks in PP-PEI / MOF@COF are observed in the 530-700 cm⁻¹ range. -1 The absence of obvious absorption peaks indicates that the COF material was successfully modified on the NH2-UIO-67-Fe surface. (725-925 cm⁻¹) -1 795cm -1 With 880cm -1 The absorption peak at 822 cm⁻¹ originates from the stretching and bending vibrations of the CH group on the benzene ring. Compared to NH₂-UIO-67-Fe and PEI / MOF, PP-PEI / MOF exhibits a higher absorption peak at 822 cm⁻¹. -1 An additional absorption peak was observed in the 1100-1700 cm⁻¹ region, resulting from the bending vibration of the triazine ring compound. Furthermore, [the text abruptly ends here, likely due to an incomplete sentence or missing information]. -1 The absorption peaks at [value missing] are attributed to the CN / C=N and CO / C=O stretching vibrations. The lower characteristic peak intensities of the PP-PEI / MOF@COF composite material compared to these two may be due to reduced crystallinity of the composite material. The stretching vibrations of water molecules, OH, and NH are observed in the 2800-3400 cm⁻¹ range.-1 This causes a broad absorption peak. After the composite material is synthesized, the structure changes, which weakens, shifts, or causes the absorption peak to disappear.

[0043] IV. Electrochemical Impedance Spectroscopy and Cyclic Current Curve Analysis: The photoelectric performance of the composite photocatalyst material was tested using an electrochemical workstation. The main test items were electrochemical impedance spectroscopy and cyclic current curves. A three-electrode system was used for electrochemical performance testing. An Ag / AgCl electrode was used as the reference electrode, a platinum sheet electrode as the counter electrode, and a glassy carbon electrode (3 mm inner diameter) modified with the composite photocatalyst material was used as the working electrode. The electrolyte was a 0.1 M Na₂SO₄ solution. The three electrodes were connected to the electrochemical workstation. Test conditions: scan frequency range of 0.01-10 kHz, voltage amplitude of 10 mV.

[0044] Electrochemical impedance spectroscopy and cycling current curves of the photocatalyst PP-PEI / MOF@COF can be used to study its photogenerated electron excitation and transfer rates under illumination. The results are as follows: Figure 4 As shown in the figure, the smaller the radius of the EIS curve, the lower the charge transport impedance and the higher the separation rate of photogenerated electron-hole pairs. The EIS curves of NH2-UIO-67-Fe, PEI / MOF, and PP-PEI / MOF@COF are shown in the figure. Figure 4 As shown, it is evident that the impedance radius of the material gradually decreases as PEI and COF are modified on the MOF surface.

[0045] The ring area in a CV curve is an indicator used to evaluate the activity of an electrochemical reaction; a larger ring area indicates higher electrochemical activity. The CV curves for NH2-UIO-67-Fe, PEI / MOF, and PP-PEI / MOF@COF are shown below. Figure 5 As shown, the order of ring domain area size is: PP-PEI / MOF@COF > PEI / MOF > NH2-UIO-67-Fe. The COF-modified PP-PEI / MOF@COF has a larger electrochemical active region and a higher surface electron density than NH2-UIO-67-Fe, which is beneficial for electron transfer in the photocatalytic process.

[0046] V. Analysis of UV-Vis Diffuse Reflectance Spectra: Two standard white plates (filled with barium sulfate) were prepared. The prepared standard white plates were placed in the reference and sample slots, the baseline was adjusted, and the sample slot was removed. The sample from Example 1 was added to a diameter of approximately 1 cm in the center of the sample slot, flattened with a glass column, and then placed in the test chamber. The test wavelength range was 200-700 nm. The UV-Vis diffuse reflectance spectra were obtained, as shown below. Figure 6 As shown, PP-PEI / MOF@COF exhibits good light absorption performance in the 350-600nm range. Figure 6The inset is based on UV-Vis diffuse reflectance spectral data, expressed in Ahv. 2 Plotting hv, the calculated bandgap of PP-PEI / MOF@COF is 2.40 eV.

[0047] Application Example 1 1) Prepare a 20 mg / L tetracycline solution.

[0048] 2) Take the reactor, wash and dry it, place it under a 300W xenon lamp, add 100mL of tetracycline solution at 20mg / L, and then add PP-PEI / MOF@COF composite photocatalysts at concentrations of 0.02g / L, 0.05g / L, 0.08g / L and 0.10g / L respectively. Then start the magnetic stirrer.

[0049] 3) Dark reaction stage: Turn on the magnetic stirrer and react for 30 minutes in the dark.

[0050] 4) Photocatalytic reaction stage: Turn on the condenser system and the xenon lamp to begin photocatalysis. Take 1 mL of solution at 5, 10, 15, 20, and 30 minutes, centrifuge for 5 minutes, discard the supernatant, and analyze the peak area of ​​the supernatant using a liquid chromatograph. Record the data.

[0051] 5) The HPLC detection conditions used in this invention are as follows: Column: C18 (4.6 mm × 250 mm, 5 μm); Mobile phase: Phase A is 0.2% acetic acid, Phase B is acetonitrile, and Phase C is methanol, with isocratic elution (A:B:C = 76:14:10, V / V).

[0052] Flow rate: 1.0 mL / min; Detection wavelength: 350nm; Column temperature: 35℃; Injection volume: 10 μL.

[0053] Degradation diagrams of tetracycline by different concentrations of PP-PEI / MOF@COF composite photocatalyst were obtained, as shown below. Figure 7 As shown (the horizontal axis represents the dark reaction stage from -30 min to 0 min, with illumination starting from 0 min), it can be seen that, considering the degradation efficiency of tetracycline by different concentrations of PP-PEI / MOF@COF composite photocatalyst, the 0.08 g / L PP-PEI / MOF@COF composite photocatalyst achieved the highest degradation efficiency for tetracycline, reaching 79.34% within 30 min.

[0054] This demonstrates that the PP-PEI / MOF@COF composite photocatalyst of the present invention has excellent photocatalytic degradation performance, and the PP-PEI / MOF@COF composite photocatalyst prepared by the present invention can be applied to the treatment of antibiotic wastewater.

[0055] Comparative Example 1 Same as Example 1, except that the mass ratio of PEI / MOF, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and p-phenylenediamine is 20 mg: 20 mg: 8.3 mg.

[0056] Using the method described in Application Example 1, the catalyst prepared in this comparative example was used to remove tetracycline at a catalyst concentration of 0.08 g / L and a tetracycline concentration of 20 mg / L. The results are as follows... Figure 8 As shown, the degradation rate of tetracycline reached 65.43% after 30 minutes of degradation.

[0057] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a composite photocatalyst doped with a metal-organic framework and a covalent organic framework, characterized in that, Specifically, the following steps are included: Using 3,3'-diaminobiphenyl dicarboxylic acid as an organic ligand, ferric chloride hexahydrate as a metal ion, and N,N-dimethylacetamide as a reaction solution, the first reaction was carried out to obtain NH2-UIO-67-Fe; A second reaction was carried out using NH2-UIO-67-Fe and a diluted solution of polyethyleneimine as the reaction substrate and methanol as the reaction solution to obtain PEI / MOF. Using PEI / MOF as the reaction substrate, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and p-phenylenediamine as covalent organic framework PP-COF monomers, o-dichlorobenzene and n-butanol as the reaction solution, and acetic acid solution as the regulator, a third reaction was carried out to obtain the PP-PEI / MOF@COF composite photocatalyst.

2. The method for preparing the composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks according to claim 1, characterized in that, The molar ratio of 3,3'-diaminobiphenyl dicarboxylic acid and ferric chloride hexahydrate is 1:1; The ratio of NH2-UIO-67-Fe, polyethyleneimine diluent, and methanol is 30 mg: 0.1 mL: 15 mL. The mass ratio of PEI / MOF, 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine, and p-phenylenediamine is 20 mg: 40 mg: 16.6 mg. The volume ratio of o-dichlorobenzene to n-butanol is 1:

1.

3. The method for preparing the composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks according to claim 1, characterized in that, The concentration of the acetic acid solution is 6 mol / L.

4. The method for preparing the composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks according to claim 1, characterized in that, The first reaction was carried out at 130°C for 24 hours. The second reaction was carried out at room temperature for 12 hours. The third reaction was carried out at 120°C for 72 hours.

5. A composite photocatalyst doped with metal-organic frameworks and covalent organic frameworks, prepared by the preparation method according to any one of claims 1-4.

6. The application of a composite photocatalyst doped with a metal-organic framework and a covalent organic framework as described in claim 5 for the efficient photocatalytic degradation of tetracycline under visible light.

7. The application according to claim 6, characterized in that, The concentration of the tetracycline is 0.02 g / L, and the concentration of the composite photocatalyst doped with the metal-organic framework and the covalent organic framework is 0.02-0.1 g / L.

8. The application according to claim 6, characterized in that, In the process of efficient photocatalytic degradation of tetracycline under visible light, the adsorption equilibrium time was 30 min and the degradation reaction time was 30 min.

Images