Purple-based cofs material and its photocatalytic degradation of medical and animal husbandry wastewater tandem plant growth device

Abstract

The application discloses a type of viologen-based covalent organic framework material and a synthesis method and application thereof. The viologen structure is expanded by introducing an electron donor unit, the stability of a viologen free radical is greatly enhanced, the cycle performance of a molecule is improved, the viologen-based covalent organic framework material obtained by using the viologen structure has good thermal stability and cycle stability, and has the advantages of reversible oxidation-reduction peaks and the like, and can be used as a catalyst for photocatalytic degradation of tetracycline antibiotic drugs. The photocatalytic degradation medical livestock wastewater tandem plant growth device built by combining the catalyst with a circulating pump, a metal mesh and the like can be directly used as a "wastewater" to "fertilizer water" device for agricultural irrigation, has a high degradation efficiency, high cycle stability and can promote the development of a plant root system.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology of photocatalytic materials, specifically involving the preparation and application of a class of viologen-based covalent organic framework materials and a photocatalytic degradation device for medical and livestock wastewater in series with plant growth. Background Technology

[0002] Antibiotics are widely used in medicine and animal husbandry due to their effectiveness in treating bacterial infections. However, the production and overuse of antibiotics result in the discharge of large amounts of antibiotic wastewater into the environment. Although the concentration of antibiotic residues in water systems is low, it can still cause extremely negative environmental impacts, such as antibiotic resistance in bacteria, damage to ecosystems, and potential risks to human health. Several efficient and economical technologies for removing antibiotics from wastewater have been developed, including adsorption, microbial degradation, electrolysis, photocatalysis, and membrane separation. Among these, photocatalysis has attracted widespread attention due to its environmental friendliness, economy, and high efficiency. However, the performance of photocatalysis largely depends on the photocatalyst used; therefore, designing a low-cost and efficient photocatalytic material is crucial. Organic photovoltaic materials have attracted widespread attention among photocatalytic materials due to their abundance, low cost, and environmental friendliness. Conjugated radical cations have wide applications in catalysis, energy storage, and electrochromic displays due to their unique properties; furthermore, conjugated radical cations are widely used in photocatalytic water treatment because the free radicals they generate can effectively degrade pollutants.

[0003] Covalent organic frameworks (COFs) are crystalline organic materials characterized by pre-designed polygonal networks with highly ordered channels. When the symmetry and planarity of each monomer are fixed, the resulting COFs can evolve into two-dimensional (2D) periodic frameworks, which are further coaxially stacked together through overlapping π interactions. This endows COFs with outstanding light absorption and strong electrical conductivity. Most reported COFs are semiconductor materials with band gaps of 1.5–3.0 eV. Due to their covalent nature, these materials are robust and stable in air and various solvents, only beginning to degrade at high temperatures, thus making their photoelectric conversion performance unique in photocatalytic applications. COFs materials that are insoluble in most solvents have attracted much attention: (i) insoluble materials are easy to purify by simple washing, while soluble materials require more complex purification techniques; (ii) insoluble materials are easy to separate from suspensions, which greatly facilitates recycling without causing significant material loss, improves cost-effectiveness, and minimizes waste; (iii) convenient separation simplifies the regeneration and reuse of materials. These properties make COFs materials that are insoluble in most solvents particularly important in fields such as catalysis and pollutant removal, and they have been successfully used in catalysis, removal of pollutants from water and organic solvents, biomedical applications, and sensing.

[0004] Viologen analoges RV 2+ Selenium is an organic radical compound that readily generates cationic free radicals upon gaining electrons, and it has wide applications in optoelectronics. Selenium atoms combine with the viologen framework to form selenium-containing viologen (SeV). 2 + ), due to its free radical cation (SeV) + The excellent properties of SeV make it suitable as a photosensitizer and electron transfer agent in photocatalysis. However, existing preparation methods yield SeV... + SeV is unstable and readily dimers through intermolecular nitrogen coupling, thus limiting electron transfer processes. Furthermore, photocatalysis requires the selective transfer of electrons from viologen cations to the metal catalytic center while suppressing charge recombination and other pathways; the competition between these pathways also affects SeV. 2+ Its role in optoelectronic applications is limited. There are few reports on using viologen, a main group element, as a free radical to degrade pollutants, especially antibiotic pollutants. Existing photocatalytic water treatment devices only address the wastewater treatment stage and do not fully utilize the beneficial elements in the treated water.

[0005] Therefore, the SeV obtained by existing preparation methods + The instability of the material limits its electron transfer process, thus affecting its application in photocatalysis. Developing new organic photocatalytic degradation materials, especially selenium-containing viologen derivatives, to improve their photocatalytic performance is crucial. At the same time, designing a novel photocatalytic degradation device for medical and livestock wastewater in series with a plant growth device is essential to fully realize the economic and agricultural benefits of the treated wastewater. Summary of the Invention

[0006] SeV obtained by existing preparation methods + The instability of viologen-based covalent organic framework materials limits their electron transfer process and thus affects their application in photocatalysis. The first objective of this invention is to provide a class of viologen-based covalent organic framework materials. The second objective of this invention is to provide a method for synthesizing viologen-based covalent organic framework materials. The third objective of this invention is to provide a device for photocatalytic degradation of medical and livestock wastewater using viologen-based covalent organic framework materials.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention provides a class of viologen-based covalent organic framework materials, the structural units of which are shown below:

[0009]

[0010] In the formula, R1 is For any one of them, R2 is Any one of them.

[0011] Furthermore, the viologen-based covalent organic framework material has the following structural unit:

[0012]

[0013] The synthesis steps of the viologen-based covalent organic framework material include: dispersing monomer I and monomer II in a mixed solvent and reacting at 110-130℃ for 24-48h to obtain a suspension; cooling the suspension to room temperature, washing, drying, and grinding to obtain the viologen-based covalent organic framework material.

[0014] Wherein, monomer I is selected from any one of compounds 1 to 3.

[0015]

[0016] Monomer II is selected from any one of compounds 4 to 5.

[0017]

[0018] The preparation method of compound 5 in monomer II is as follows: Compound 6, compound 7 and copper acetate are dissolved in N,N-dimethylformamide (DMF), the resulting mixture is heated to 90-110℃ and stirred for 24-48 h, cooled to room temperature, dichloromethane is added to precipitate, and the mixture is separated by vacuum filtration and washed to obtain compound 4. The specific reaction is as follows:

[0019]

[0020] The molar ratio of monomer I to monomer II is 1:1 to 1:1.5.

[0021] The molar ratio of compound 6, compound 7 and copper acetate is 20:2:1.

[0022] A device for photocatalytic degradation of medical and livestock wastewater prepared from viologen-based covalent organic framework material includes a power unit, a catalytic unit, and a reuse unit. The power unit and the catalytic unit are connected. The wastewater treated by the catalytic unit flows directly into the tank of the reuse unit through a pipeline. The power unit consists of a peristaltic pump. The photocatalytic unit consists of a metal mesh supported by a cylindrical viologen-based covalent organic framework material and placed inside a high borosilicate glass hollow tube. The reuse unit consists of a hydroponic tank.

[0023] The above-mentioned viologen-based covalent organic framework materials are used in the photocatalytic degradation of antibiotics.

[0024] The application of the above-mentioned viologen-based covalent organic framework material photocatalytic degradation device for medical and livestock wastewater in wastewater treatment.

[0025] The above-mentioned viologen-based covalent organic framework materials are used in wastewater treatment in animal husbandry.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The method for synthesizing viologen-based covalent organic framework materials provided by the present invention expands the viologen structure by introducing electron donor units, and realizes the direct arylation of viologen molecules for the first time, which improves its free radical stability and electron transfer rate, and stabilizes the molecular structure. It solves the technical problem that the selenium-containing viologen obtained by the existing preparation method is unstable, which restricts its electron transfer and thus affects its application in photocatalysis. The method of preparing covalent organic framework materials by one-pot method uses inexpensive solvents, is simple, has high yield, can be synthesized in large quantities, and has a fast synthesis speed.

[0028] (2) The viologen-based covalent organic framework material provided by the present invention has extremely poor solubility in organic solvents. Under visible light excitation, it generates photogenerated electrons and photogenerated holes. Both the photogenerated holes and photogenerated electrons interact with antibiotics, exhibiting strong photocatalytic activity and good cycle stability. When used as a catalytic unit in a plant growth device for photocatalytic degradation of medical and livestock wastewater, the treated wastewater is rich in nitrogen nutrients and can be used as fertilizer to promote plant growth. Therefore, the viologen-based covalent organic framework material provided by the present invention can be used in the field of removing pollutants from water and organic solvents, and is particularly suitable for water treatment and agricultural applications. The development of such viologen-based covalent organic framework materials in wastewater treatment is of great significance. Attached Figure Description

[0029] Figure 1 The image shown is a field photo of the photocatalytic degradation device for medical and livestock wastewater connected in series with plant growth provided by this invention.

[0030] Figure 2 The image shows a metal mesh supported on a viologen-based covalent organic framework material provided by this invention.

[0031] Figure 3 The image shows a comparison of the XRD diffraction pattern and the calculated XRD pattern of the viologen-based covalent organic framework material provided by the present invention.

[0032] Figure 4 The image shown is a transmission electron microscope (TEM) image of the viologen-based covalent organic framework material provided by the present invention.

[0033] Figure 5 The image shown is a scanning electron microscope image of the viologen-based covalent organic framework material provided by the present invention.

[0034] Figure 6 The image shown is a solid-state NMR spectrum of the viologen-based covalent organic framework material provided by the present invention.

[0035] Figure 7 The diagram shows the thermogravimetric curve of the viologen-based covalent organic framework material provided by the present invention.

[0036] Figure 8 The image shown is an XPS plot of the viologen-based covalent organic framework material provided by the present invention.

[0037] Figure 9 The image shown is an electrochemical spectrum of the viologen-based covalent organic framework material provided by the present invention.

[0038] Figure 10 The image shown is a solid-state EPR electrochemical spectrum of the viologen-based covalent organic framework material provided by the present invention.

[0039] Figure 11 The graphs shown are performance test results of the viologen-based covalent organic framework material provided by the present invention under different conditions.

[0040] Figure 12 The diagram shown is a catalytic cycle test diagram of the viologen-based covalent organic framework material provided by the present invention. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0042] The present invention will now be described in further detail with reference to the accompanying drawings:

[0043] Example 1

[0044] The viologen-based covalent organic framework material provided in this embodiment was obtained by the coupling reaction of compound 3 and compound 5. The specific synthesis method is as follows:

[0045] 8 mg (0.025 mmol) of compound 3 and 17.6 mg (0.02 mmol) of compound 5 were dispersed in 2.5 mL of a triethylamine:toluene mixture of 1:1.5 and allowed to stand at 120 °C for 48 h to obtain a suspension. The suspension was cooled to room temperature and then washed sequentially with acetonitrile, diethyl ether, and dichloromethane. After drying and grinding, viologen-based covalent organic framework materials were obtained, the structural units of which are shown below:

[0046]

[0047] The synthesis method of compound 5 is as follows: compound 6 (1300 mg, 2.2 mmol), compound 7 (52 mg, 0.22 mmol), and copper acetate (6.0 mg, 0.03 mmol) were dissolved in dry DMF (10 mL); the resulting mixture was heated to 100 °C and stirred for 36 h, cooled to room temperature, and then added dropwise to 50 mL of dichloromethane; the precipitate formed was separated by vacuum filtration, and then thoroughly washed with dichloromethane and diethyl ether; after vacuum filtration, compound 4 was obtained as a yellow solid with a yield of 74%.

[0048] The chemical reaction formula is:

[0049]

[0050] Example 2

[0051] The viologen-based covalent organic framework material provided in this embodiment was obtained by the coupling reaction of compound 3 and compound 4. The specific synthesis method is as follows:

[0052] 8.0 mg (0.025 mmol) of compound 3 and 17.6 mg (0.03 mmol) of compound 4 were dispersed in 2.5 mL of a triethylamine:toluene mixture of 1:1.5 and allowed to stand at 120 °C for 48 h to obtain a suspension. After cooling the suspension to room temperature, it was washed sequentially with the organic solvents acetonitrile, diethyl ether, and dichloromethane, dried, and ground to obtain viologen-based covalent organic framework materials, the structural units of which are shown below:

[0053]

[0054] The synthesis method of compound 4 is as follows: compound 8 (1440 mg, 2.6 mmol), compound 9 (40 mg, 0.26 mmol), and copper acetate (6.0 mg, 0.03 mmol) were dissolved in dry DMF (10 mL); the resulting mixture was heated to 100 °C and stirred for 36 h, cooled to room temperature, and then added dropwise to 50 mL of dichloromethane; the precipitate formed was separated by vacuum filtration, and then thoroughly washed with dichloromethane and diethyl ether; after vacuum filtration, compound 4 was obtained as a yellow solid with a yield of 87%.

[0055] The chemical reaction formula is:

[0056]

[0057] Example 3

[0058] The viologen-based covalent organic framework material provided in this embodiment was obtained by the coupling reaction of compound 1 and compound 5. The specific synthesis method is as follows:

[0059] 7.9 mg (0.025 mmol) of compound 1 and 17.6 mg (0.02 mmol) of compound 5 were dispersed in 2.5 mL of a triethylamine:toluene mixture of 1:1.5 and allowed to stand at 120 °C for 48 h to obtain a suspension. The suspension was cooled to room temperature and then washed sequentially with acetonitrile, diethyl ether, and dichloromethane. After drying and grinding, viologen-based covalent organic framework materials were obtained, the structural units of which are shown below:

[0060]

[0061] Example 4

[0062] The viologen-based covalent organic framework material provided in this embodiment was obtained by the coupling reaction of compound 2 and compound 5, and the specific synthesis method is as follows:

[0063] 9.5 mg (0.025 mmol) of compound 2 and 17.6 mg (0.02 mmol) of compound 5 were dispersed in 2.5 mL of a triethylamine:toluene mixture of 1:1.5 and allowed to stand at 120 °C for 48 h to obtain a suspension. The suspension was cooled to room temperature and then washed sequentially with acetonitrile, diethyl ether, and dichloromethane. After drying and grinding, viologen-based covalent organic framework materials were obtained, the structural units of which are shown below:

[0064]

[0065] Example 5

[0066] Application of viologen-based covalent organic framework materials provided in Example 1

[0067] This embodiment, based on Examples 1-2, applies the viologen-based covalent organic framework material prepared by the above-mentioned coupling reaction in a medical and livestock wastewater treatment device. See Appendix for the device. Figure 1 As shown, it can be assembled and prepared through the following steps:

[0068] Step 1: Preparation of the core catalytic material monomer;

[0069] The photocatalytic functional material for a plant growth device cascaded in conjunction with medical and livestock wastewater photocatalytic degradation is prepared by the synthesis method disclosed in this patent. This material is a type of viologen-based covalent organic framework material with a hexagonal porous structure. Preparation of the monomers: Compounds 8, 9, and copper acetate are dispersed in dry N,N-dimethylformamide in a reaction tube. The resulting mixture is heated to 100°C and stirred for 36 hours. After cooling to room temperature, the mixture is added dropwise to 50 mL of dichloromethane. The resulting precipitate is separated by vacuum filtration and then thoroughly washed with dichloromethane and diethyl ether. After vacuum filtration, compound 5 is a yellow solid.

[0070] Step 2: Preparation and loading of core catalytic covalent organic framework materials;

[0071] (1) Pretreatment of metal mesh: Place the metal mesh in a 500mL beaker and clean it ultrasonically for 30 minutes with ultrapure water and anhydrous ethanol in sequence to remove the oil film on the metal surface; place the cleaned metal mesh in a vacuum oven and dry it for 1 hour; polish it with 800-grit and 400-grit diamond sandpaper in sequence until the surface is rough and dull; then place the metal mesh in a 500mL beaker again and clean it ultrasonically for 30 minutes with ultrapure water and anhydrous ethanol in sequence to remove the metal surface debris, and then dry it to complete the pretreatment of the metal.

[0072] (2) Preparation and loading of covalent organic framework materials;

[0073] Different monomer combinations were added to a specific mixed solvent in a pressure-resistant reaction flask and ultrasonically dispersed for 30 minutes. Then, the treated metal mesh was added to the flask, and the mixture was slowly heated to 120°C and reacted without stirring for 48 hours to obtain a suspension. After cooling the reaction solution to room temperature, the metal mesh was removed. A significant color change was observed in the metal mesh, indicating that some covalent organic framework material was loaded onto it. The mesh was washed three times sequentially with acetonitrile, diethyl ether, and dichloromethane, and then dried to obtain the metal mesh loaded with covalent organic framework material. (See Appendix for details.) Figure 2 As shown.

[0074] Step 3: Assembly of the core catalytic unit;

[0075] A metal mesh loaded with a covalent organic framework material is shaped into a hollow cylinder using a tubular mold. The cylindrical metal mesh is then inserted into a high borosilicate glass hollow tube. The tubular mold is then removed, and the processed metal mesh and high borosilicate glass are assembled together to form the core unit of the catalysis.

[0076] Step 4: Assemble a photocatalytic degradation device for medical and livestock wastewater in series with a plant growth device;

[0077] The photocatalytic degradation device for medical and livestock wastewater, connected in series with a plant growth system, mainly consists of three parts: a power unit, a catalytic unit, and a reuse unit. The power unit, composed of a peristaltic pump, pumps the medical and livestock wastewater from the storage tank into the catalytic unit. The photocatalytic unit is assembled according to the specific steps described in step three. The reuse unit consists of a hydroponic tank, which uses the photocatalytically degraded wastewater to hydroponically cultivate plants, promoting plant growth. The power unit, catalytic unit, and reuse unit are connected sequentially by external pipes and secured with a base plate. The fixation should be checked for looseness; if loose, it should be reinforced. Before testing, a sealing and pressure test should be performed. Connect a regular water storage bottle and the peristaltic pump to the above components. After one hour of circulation, if there is no leakage or change in liquid volume, it can be stored for later use. If any leaks occur, readjustment is required.

[0078] Step 5: Performance testing of the photocatalytic degradation of medical and livestock wastewater in series with a plant growth device.

[0079] (1) Performance testing of catalytic core materials

[0080] The photocatalytic activity of the core catalytic material was evaluated by assessing the relationship between the removal rate of tetracycline in tetracycline wastewater and time. The tetracycline degradation test was conducted using a 300W xenon lamp with an added filter (λ>420nm) and a radiation intensity of 100mW·cm⁻¹. -1 In each degradation experiment, the catalyst was added at a rate of 1 mg / 10 mL. -1 The tetracycline solution concentration is 20 mg·L⁻¹ -1 Before illumination, the solution was sonicated for 10 minutes and stirred in the dark for 1 hour to reach adsorption equilibrium. After the light was turned on, samples were taken every 20 minutes, and the concentration of the pollutant solution was measured using a UV-Vis spectrometer.

[0081] (2) Performance testing in a laboratory environment

[0082] The device performance was tested in a laboratory environment under a 300W xenon lamp with a filter (λ>420nm) and a radiation intensity of 100mW·cm. -2 The ambient temperature was 25℃, and the concentration of tetracycline antibiotic wastewater was 20 mg·L⁻¹. -1 Before illumination, the tetracycline antibiotic wastewater was sonicated for 10 minutes. After the lights were turned on, samples were taken every 20 minutes, and the concentration of the pollutant solution was measured using a UV-Vis spectrometer.

[0083] (3) Performance testing under natural light environment

[0084] The device performance testing under natural light conditions was conducted outdoors in a well-ventilated environment. The outdoor temperature on the day of the test was 21-24℃, and the irradiance of the catalytic section measured by the radiometer was 60-70 mW·cm⁻¹. -2 The irradiation intensity is lower than that under laboratory conditions. Place the device prepared in step four in a well-ventilated outdoor location. Add tetracycline antibiotic wastewater to the storage bottle, connect an external power source and a peristaltic pump, and check for leaks. Once the checks are complete and everything is in order, performance testing can be conducted. It should be noted that plant seeds used for hydroponic growth promotion in the degraded solution need to be soaked in water for 6 hours to promote earlier germination.

[0085] After the above steps, the test data of the catalytic core material are as follows: the degradation rate of tetracycline antibiotics is 97% under air conditions within 160 minutes; the degradation rate of tetracycline antibiotics is 51% under argon conditions; the degradation rate of tetracycline antibiotics is 96% under laboratory conditions; the degradation rate of tetracycline antibiotics is 94% under natural light conditions; and the root system of hydroponically cultivated plants shows that the root system of the catalytic core material group is more developed and longer than that of the control group.

[0086] The degradation rate under air conditions was significantly higher than that under argon conditions. Besides excellent photocatalytic activity, reusability and stability also have a significant impact on the practical industrial application of photocatalysts. Therefore, we conducted cyclic photocatalysis experiments to evaluate the reusability of the catalyst. After four cycles and 640 minutes of use, the catalyst maintained a 48% degradation rate under argon conditions and an 89% degradation rate under air conditions, with a performance loss of only 4.4%. This demonstrates the good cyclic stability of the viologen-based covalent organic framework material used in photodegradation. Furthermore, the surface morphology of the catalyst remained almost unchanged before and after use, further demonstrating the stability of the viologen-based covalent organic framework material.

[0087] The degradation pathway of pollutants under visible light irradiation using photocatalytic materials was deduced using high-performance liquid chromatography-mass spectrometry and ion chromatography. The active species attacked the active site of tetracycline, oxidizing the hydroxyl group and double bond. Next, further ring-opening occurred through oxidation and denitrification. As the active site was further attacked by the active species, it gradually degraded into small molecules with a molecular weight of approximately 100. The photocatalytic process did not stop after the decomposition of organic molecules; it proceeded towards the complete mineralization of organic matter, forming CO2, H2O, and NH4. + and NO3 - .

[0088] Therefore, the tests confirmed that viologen-based covalent organic framework materials are excellent photocatalytic degradation catalysts. Viologen molecules themselves can achieve rapid electron transfer. Modification of viologen with other structures or extended viologen enhances radical stability and electron transfer rate, while simultaneously stabilizing the molecular structure. Compared to metal oxides and complex molecules, this method avoids the use of metal elements, significantly reducing costs. The heterogeneous catalytic nature also results in extremely high recyclability, further improving its cost-effectiveness.

[0089] The present invention conducts relevant tests on the viologen-based covalent organic framework material, and the specific test results are shown in the appendix. Figure 3-7 .

[0090] From the appendix Figure 3Data shows that the viologen-based covalent organic framework material obtained by this invention exhibits multiple diffraction peaks at 3-10° (4.4, 5.4, 7.0). The experimentally obtained XRD pattern is consistent with the calculated value fitted by Material Studio, further proving that the synthesis method provided by this invention successfully constructed the viologen-based covalent organic framework material, and the broad peak at around 20° should be a manifestation of layered stacking.

[0091] Appendix Figure 4 and attached Figure 5 The images shown are transmission electron microscope (TEM) and scanning electron microscope (SEM) images of the viologen-based covalent organic framework material in Example 1 of this invention. It can be seen that the material exhibits a smooth nanorod and nanosheet structure with a width of 0.5-1.0 micrometers due to its layered stacking.

[0092] Appendix Figure 6 The solid-state NMR spectrum of the viologen-based covalent organic framework material in Example 1 of this invention shows that the asymmetric peak at 170 ppm can be attributed to carbon atoms in the ternary structure, while the asymmetric peak at 129 ppm can be attributed to the aromatic ring and carbon atoms and viologen units near the ternary structure, proving that the synthesis method provided by this invention successfully constructed the viologen-based covalent organic framework material.

[0093] Appendix Figure 7 The thermogravimetric curves show that the viologen-based covalent organic framework material remains relatively stable at 500℃ and retains about 60% of its initial mass after complete decomposition at 700℃, exhibiting good thermal stability.

[0094] Appendix Figure 8 The XPS plot further demonstrates the elemental composition and distribution of the viologen-based covalent organic framework material, further proving the successful construction of the material.

[0095] From the appendix Figure 9 Data shows that the viologen-based covalent organic framework material provided by this invention exhibits excellent light response. (See attached...) Figure 10 The data show that the electron paramagnetic resonance spectrum exhibits typical free radical signals. The g-factors (2.0055, 2.0024) of the viologen-based covalent organic framework material are almost equal to the g-factor of the free electrons (2.0023), indicating the characteristics of organic free radicals. This suggests that the viologen-based covalent organic framework material obtained in this invention possesses unique optical and electrochemical properties, making it potentially applicable to the field of photocatalysis.

[0096] From the appendix Figure 11 Data shows that a 97% degradation rate of the antibiotic tetracycline was achieved within 160 minutes under air conditions, and a 51% degradation rate was achieved under argon conditions; the degradation rate of the antibiotic tetracycline under laboratory conditions was 96%. (See attached...) Figure 12Data shows that after 4 cycles and 640 minutes of catalyst use, the organic framework material maintained a 48% degradation rate of the antibiotic tetracycline under argon conditions and an 89% degradation rate under air conditions, with a performance loss of only 4.4%.

[0097] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A class of viologen-based covalent organic framework materials, characterized in that, The structural unit of the viologen-based covalent organic framework material is shown below: In the formula, R1 is R2 is .

2. A method for synthesizing a viologen-based covalent organic framework material as described in claim 1, characterized in that, The synthesis steps of the viologen-based covalent organic framework material include: dispersing 0.025 mmol monomer I and 0.02 mmol monomer II in a mixed solvent of triethylamine and toluene with a volume ratio of 1:1.5, reacting at 120°C for 48 h to obtain a suspension; cooling the suspension to room temperature, washing, drying, and grinding to obtain the viologen-based covalent organic framework material. The structural formula of monomer I is as follows: ; The structural formula of monomer II is: .

3. The method for synthesizing viologen-based covalent organic framework materials as described in claim 2, characterized in that, The preparation method of compound 5 is as follows: compound 6, compound 7 and copper acetate are dissolved in N,N-dimethylformamide, the resulting mixture is heated to 100 °C and stirred for 36 h, cooled to room temperature, dichloromethane is added to precipitate, and the mixture is separated by vacuum filtration and washed to obtain compound 5; The structural formula of compound 6 is: The structural formula of compound 7 is .

4. The method for synthesizing viologen-based covalent organic framework materials as described in claim 3, characterized in that, The amount of compound 6 was 2.2 mol, the amount of compound 7 was 0.22 mol, and the amount of copper acetate was 0.03 mol.

5. The application of the viologen-based covalent organic framework material as described in claim 1 in the photocatalytic degradation of antibiotics.

6. The application of the viologen-based covalent organic framework material as described in claim 1 in wastewater treatment.

7. A photocatalytic degradation device for medical and livestock wastewater tandem with plant growth, prepared from viologen-based covalent organic framework material as described in claim 1, characterized in that... The photocatalytic component consists of a metal mesh supported by viologen-based covalent organic framework material, which is then packed into a high borosilicate glass hollow tube.

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