Preparation of Covalent Organic Framework Fiber Membrane and Its Application in Catalytic Degradation of Antibiotics

Abstract

The present invention relates to the field of photocatalytic water treatment of organic pollutants, and specifically to the preparation of covalent organic framework fiber membranes and their application in the catalytic degradation of antibiotics. The preparation process of the covalent organic framework fiber membrane includes: uniformly dispersing a functional COF photocatalyst in a casting agent and an organic solvent, stirring evenly to obtain a spinning solution, and using it for electrospinning. After electrospinning, drying is carried out to obtain the covalent organic framework fiber membrane. The covalent organic framework fiber membrane of the present invention exhibits good performance in photocatalytically degrading antibiotic pollution in the water environment, and at the same time overcomes the problems of low degradation efficiency, difficult recovery, and poor reuse effect of traditional photocatalysts. As a photocatalytic system that does not require the addition of additional oxidants, it can be applied to the removal of antibiotics in various water environments, with simple operation and high feasibility, and has good environmental and social benefits.

Description

Technical Field

[0001] The present invention relates to the field of photocatalytic water treatment of organic pollutants, and particularly to the preparation of covalent organic framework fiber membranes and their application in catalytic degradation of antibiotics. Background Art

[0002] As a class of compounds that can inhibit the proliferation of microorganisms, antibiotics are widely used in the prevention and treatment of infectious diseases in humans and animals. As a result, a large amount of antibiotics enter the environmental water bodies. Although the concentration level of antibiotics in natural water bodies is very low, most types of antibiotics are not easily degraded and are relatively stable in the water environment. Even at low concentration levels, antibiotics may directly be toxic to aquatic organisms. For example, they can cause poisoning of phytoplankton, inhibit the communication between microorganisms, and change the microbial community structure. In addition, the long-term existence of antibiotic pollution in the environment induces the occurrence of drug-resistant bacteria, which ultimately pose a hazard to human health during the process of biological magnification.

[0003] Using photocatalytic oxygen activation degradation technology to remove antibiotic pollution in water environment is a relatively new water treatment method at present. In this process, dissolved oxygen in water is converted into reactive oxygen species to break down antibiotic molecules, and further transformed into small molecule substances or mineralized. Moreover, the photocatalytic oxygen activation degradation technology has mild reaction conditions, is green and environmentally friendly, and has no secondary pollution. Among them, covalent organic framework (COF) is an emerging crystalline porous organic polymer, which has advantages such as large specific surface area, flexible and easy-to-regulate structure, controllable performance, and easy functionalization. It is often used as a photocatalytic oxygen activation degradation technology for organic pollution water treatment.

[0004] However, there are still deficiencies in the application of COF materials in the field of photocatalytic pollutant degradation. For example, it is difficult to recycle the photocatalytic materials after water treatment, the material has a low multiple reuse rate, and the photocatalytic degradation efficiency is low. Therefore, it is of great significance to develop a preparation method of covalent organic framework fiber membranes for removing antibiotics in photocatalytic water bodies.

[0005] In view of this, the present invention is specifically proposed to solve the above technical problems. Summary of the Invention

[0006] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide the preparation of covalent organic framework fiber membranes and their application in catalytic degradation of antibiotics. The preparation method of the covalent organic framework fiber membrane is simple and easy to implement, the equipment used is cheap and simple, large-scale sewage treatment can be realized, it is suitable for industrial development, multiple uses greatly save costs and improve the degradation efficiency. In addition, the present invention focuses on the actual application scenario, explores the degradation of antibiotic pollutants in water under natural sunlight irradiation, and optimizes the conditions of the photocatalytic system.

[0007] The present invention provides a method for preparing a covalent organic framework fiber membrane, comprising the following steps:

[0008] (1) Thoroughly mix an organic ligand with an aldehyde-terminal group and an organic ligand with a cyano-terminal group, add o-dichlorobenzene, n-butanol, and an aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene for mixing. After the mixed solution is subjected to vacuum freeze degassing three times, seal the bottle mouth and carry out the Knoevenagel condensation reaction to obtain a functional COF photocatalyst;

[0009] (2) Uniformly disperse the functional COF photocatalyst in a casting agent and an organic solvent, stir at a rotation speed of 400 - 600 r / min until the solution is uniform and free of particles to obtain a spinning solution for electrospinning. After electrospinning, dry it to obtain a covalent organic framework fiber membrane;

[0010] The casting agent is one of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF); the organic ligand with an aldehyde-terminal group is one of 1,3,6,8-tetrakis(4-formylphenyl)pyrene, 5,5',5'',5'''-(pyrene-1,3,6,8-tetraphenyl)tetrapyridinecarbaldehyde, and N,N,N',N'-tetrakis(4-formylphenyl)-1,4-benzenediamine; the organic ligand with a cyano-terminal group is one of 2,2'-bipyridine-5,5'-dicarbonitrile, terephthalonitrile, and 4,4'-biphenyldicarbonitrile.

[0011] Further, in the spinning solution, the concentration of the functional COF photocatalyst is 5 - 15 wt%, and the concentration of the casting agent is 10 - 20 wt%.

[0012] Further, the molar ratio of the organic ligand with an aldehyde-terminal group to the organic ligand with a cyano-terminal group is (1 - 3):(2 - 4).

[0013] Further, the concentration of the aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene is 1 - 5 mol / L, and the volume ratio of o-dichlorobenzene, n-butanol, and the aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene is (0.5 - 2):(0.5 - 2):(0.1 - 0.5).

[0014] Further, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, and acetone.

[0015] Furthermore, the parameters of the electrospinning are as follows: high voltage of 15 - 25 kV, low voltage of 0.25 kV; the distance between the roller and the receiving device is 30 cm, the receiving speed is 80 - 100 r / min; the injection speed is 0.2 - 0.5 mL / min; the translation speed of the electrospinning machine is 500 mm / min; during electrospinning, the air humidity is controlled at 50 - 65%; 5 - 10 mL of the spinning solution is used for each electrospinning; after the electrospinning, the drying temperature is 60 - 70 °C.

[0016] The present invention proposes the application of the covalent organic framework fiber membrane in the catalytic degradation of antibiotics. An aqueous solution containing antibiotic pollutants is added to the reaction pool, the covalent organic framework fiber membrane is fixed in the reaction pool, and a photocatalytic reaction is carried out under light conditions. During this period, samples are taken from the reaction pool to monitor the residual concentration of the pollutants.

[0017] Furthermore, the antibiotic is one or more of sulfamethoxazole, levofloxacin, norfloxacin, and tetracycline.

[0018] Furthermore, the light condition is one of natural sunlight, a xenon lamp with 1000 W / m 2 , λ > 420 nm, and an LED lamp. No additional oxidant is added to the photocatalytic reaction, and only the dissolved oxygen in the water body is utilized.

[0019] Furthermore, before the photocatalytic reaction, an adsorption process is carried out for 15 - 30 min under dark conditions.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention uses an organic ligand with an aldehyde - group - terminal group and an organic ligand with a cyano - group - terminal group to carry out the Knoevenagel condensation reaction to prepare a functional COF photocatalyst, then mixes it with a casting agent and an organic solvent to obtain a spinning solution, and finally obtains a covalent organic framework fiber membrane with a flexible and adjustable structure and high photocatalytic efficiency through electrospinning, which is used for photocatalytic degradation of antibiotic pollutants, thereby improving the degradation efficiency of antibiotic pollutants and increasing the number of times the covalent organic framework fiber membrane can be reused.

[0022] 2. The present invention can regulate the structure and properties of the COF material by selecting different types of organic ligands. The organic ligands in the COF material contain a π - conjugate system, which can absorb light of a specific wavelength, excite electrons to transition from the valence band to the conduction band to form electron - hole pairs. At the same time, the COF material has a highly ordered porous structure, providing a large number of active sites, increasing the contact area between light and the material, and improving the light absorption efficiency. The prepared nanofiber membrane has good mechanical strength, is easy to recover from the water body, and is suitable for large - scale applications.

[0023] 3. The covalent organic framework fiber membrane of the present invention has universality in treating antibiotic pollution in water bodies, can also achieve good antibiotic degradation efficiency under natural light conditions, has good degradation effects on different typical and commonly used antibiotics, and at the same time, the fiber membrane has good chemical stability, has no leaching risk in water bodies, does not require the addition of other oxidants, and only uses dissolved oxygen in water, without secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It shows the degradation effects of the covalent organic framework fiber membrane of the present invention on different antibiotic pollutants.

[0025] Figure 2 It shows the degradation effect of tetracycline after the covalent organic framework fiber membrane of the present invention is reused multiple times.

[0026] Figure 3 It is the SEM image of the functional COF photocatalyst of Example 1 of the present invention.

[0027] Figure 4 It is the SEM image of the covalent organic framework fiber membrane of Example 1 of the present invention.

[0028] Figure 5 It is the graph of the change of the water contact angle of the covalent organic framework fiber membrane of Example 1 of the present invention with time.

[0029] Figure 6 It is the graph of the change of the water contact angle of the covalent organic framework fiber membrane of Example 3 of the present invention with time.

[0030] Figure 7 It is the degradation activity graph of the covalent organic framework fiber membranes of Examples 1 - 3 of the present invention on tetracycline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] The present invention provides a preparation method of a covalent organic framework fiber membrane and its application in catalytic degradation of antibiotics, which will be described in detail below.

[0033] The present invention provides a preparation method of a covalent organic framework fiber membrane, including the preparation of a functional COF photocatalyst (hereinafter referred to as COF photocatalyst in the following embodiments) and electrospinning a covalent organic framework fiber membrane (hereinafter referred to as nanofiber membrane or COF nanofiber membrane in the following embodiments), including the following steps:

[0034] (a)Preparation of functional COF photocatalyst: Weigh the aldehyde organic ligand 1,3,6,8 - tetrakis(4 - formylphenyl)pyrene and the cyano organic ligand 2,2 - bipyridine - 5,5 - dicarbonitrile into a glass bottle, add the organic solvents o - dichlorobenzene and n - butanol, and ultrasonically disperse them evenly. After ultrasonic treatment, add an alkali solution to catalyze the reaction process. Conduct vacuum freeze - degassing on the glass bottle through three cycles of liquid nitrogen freezing - thawing to prevent the formation of other by - products caused by excessive oxidation reactions. The sealed glass bottle is placed in an oven for Knoevenagel condensation reaction. After the reaction, the solid product is obtained by filtration and washed with tetrahydrofuran until the washing liquid is colorless. After drying, the functional COF photocatalyst is obtained.

[0035] Among them, the ratio of 1,3,6,8 - tetrakis(4 - formylphenyl)pyrene, 2,2 - bipyridine - 5,5 - dicarbonitrile, o - dichlorobenzene, n - butanol and the alkali solution is: 29.6 mg: 23 mg: 1 mL: 1 mL: 0.2 mL. The alkali solution is one of potassium hydroxide solution and 1,8 - diazabicyclo[5,4,0]undec - 7 - ene aqueous solution. The ultrasonic time is 5 - 10 min, the condensation reaction temperature is 120 °C, and the reaction time is 72 h. The product drying temperature is 60 °C, and the drying time is 2 h.

[0036] (b)Electrospun covalent organic framework fiber membrane: The functional COF photocatalyst is stirred and mixed evenly with a casting agent and an organic solvent to obtain a uniform spinning solution for electrospinning. After electrospinning, it is dried to obtain a covalent organic framework fiber membrane.

[0037] Among them, the casting agent is one of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF), and the organic solvent is one or more of N,N - dimethylformamide, N,N - dimethylacetamide and acetone. The concentration of the COF photocatalyst is 5 - 15 wt%, and the concentration of the casting agent is 10 - 20 wt%. The stirring speed is 400 - 600 r / min. The parameters of electrospinning are a high voltage of 15 - 25 kV, a low voltage of 0.25 kV. The drum receiving distance is 30 cm, and the receiving speed is 80 - 100 r / min. The injection speed is 0.2 - 0.5 mL / min. The translation speed of the electrospinning machine is 500 mm / min. During electrospinning, the air humidity is controlled at 50 - 65%. Each electrospinning requires 5 - 10 mL of spinning solution. The drying temperature of the nanofiber membrane is 60 - 70 °C, and the drying time is 2 h.

[0038] The covalent organic framework fiber membrane prepared by the present invention exhibits outstanding efficiency in the degradation of antibiotic pollution. The specific steps are as follows: Add an aqueous solution containing antibiotic pollutants to the reaction pool, fix the covalent organic framework fiber membrane in the reaction pool, and under light conditions, take samples from the reaction pool at certain time intervals to detect the residual concentration of the pollutants.

[0039] Among them, the initial concentration of the antibiotic pollutant is 10 - 20 ppm. The antibiotic is one of sulfamethoxazole, levofloxacin, norfloxacin, and tetracycline. The light condition is one of natural sunlight, a xenon lamp with 1000 W / m 2 ², λ>420 nm, and an LED lamp. The sampling times are 0, 2, 5, 10, 15, 30, 45, and 60 min. It should be noted that no additional oxidant needs to be added during the photocatalytic reaction process.

[0040] Example 1: This example is an exemplary method for preparing a covalent organic framework fiber membrane, which includes:

[0041] Weigh 29.6 mg of 1,3,6,8 - tetra(4 - formylphenyl)pyrene and 23 mg of 2,2 - bipyridine - 5,5 - dicarbonitrile and place them in a glass bottle. Add 1 mL of o - dichlorobenzene and 1 mL of n - butanol, and ultrasonically treat for 5 min to disperse them evenly. After ultrasonic treatment, add 0.2 mL of a 5mol / L aqueous solution of 1,8 - diazabicyclo[5,4,0]undec - 7 - ene to catalyze the reaction. Perform vacuum freeze - degassing on the glass bottle through three cycles of liquid nitrogen freezing - thawing to prevent the generation of other by - products caused by excessive oxidation reactions. The sealed glass bottle is placed in an oven at 120 °C for reaction for 72 h. In the oven, 1,3,6,8 - tetra(4 - formylphenyl)pyrene and 2,2 - bipyridine - 5,5 - dicarbonitrile form a covalent organic framework through the Knoevenagel condensation reaction. After the reaction, the solid product in the glass bottle is obtained by suction filtration, washed with tetrahydrofuran until the washing liquid is colorless, and dried in an oven at 60 °C to obtain the COF photocatalyst, denoted as COF - 1. Add 5 wt% of the COF photocatalyst and 12wt% of polyacrylonitrile to a beaker, and then add 20 mL of N,N - dimethylformamide. Stir at a speed of 400 r / min for 12 h to make the spinning solution evenly dispersed. Then, perform electrospinning. Set the high voltage to 25 KV, the low voltage to 0.25 kV; the drum receiving distance to 30 cm, the receiving speed to 80 r / min; the injection speed to 0.2 mL / min; the translation speed to 0.5 cm / min. During electrospinning, the air humidity is controlled at 50 - 65%. Extract 10 mL of the spinning solution to obtain a 24*32 cm 2 covalent organic framework fiber membrane. After electrospinning, dry the fiber membrane in an oven at 60 °C for 2 h, denoted as PAN / COF - 1.

[0042] Photocatalytic Degradation Experiment of Tetracycline in Water by Covalent Organic Framework Fiber Membrane: Cut a 11*11 cm fiber membrane and fix it in an acrylic reaction cell. Add 100 mL of 10 ppm tetracycline solution to the reaction cell. Under the irradiation of a xenon lamp with 1000 W / m 2 , λ>420nm, take 1 mL of sample from the reaction cell after 0, 2, 5, 10, 15, 30, 45, 60 min, and use high performance liquid chromatography to detect the residual tetracycline concentration.

[0043] Example 2: This example is another exemplary method for preparing covalent organic framework fiber membranes. Different from Example 1, the ligands added are different, and it includes:

[0044] Weigh 29.8 mg of 5,5',5'',5'''-(pyrene-1,3,6,8-tetraphenyl)tetrapyridine aldehyde and 22.8 mg of 4,4'-biphenyldicarbonitrile and place them in a glass bottle. Add 1 mL of o-dichlorobenzene and 1 mL of n-butanol, and ultrasonically treat for 5 min to make them disperse evenly. After ultrasonic treatment, add 0.2 mL of 5 mol / L 1,8-diazabicyclo[5,4,0]undec-7-ene aqueous solution to catalyze the reaction. Perform vacuum freeze degassing on the glass bottle through three cycles of liquid nitrogen freezing-thawing to prevent the generation of other by-products caused by excessive oxidation reactions. The sealed glass bottle is placed in an oven at 120 °C for reaction for 72 h to form a covalent organic framework through Knoevenagel condensation reaction. After the reaction is completed, the solid product in the glass bottle is obtained by suction filtration, washed with tetrahydrofuran until the washing liquid is colorless, and dried in an oven at 60 °C to obtain a COF photocatalyst, denoted as COF-2. Add 5 wt% of the COF photocatalyst and 12 wt% of polyacrylonitrile to a beaker, and then add 20 mL of N,N-dimethylformamide, and stir at a speed of 400 r / min for 12 h to make the spinning solution disperse evenly. Then perform electrospinning, set the high voltage to 25 KV and the low voltage to 0.25 kV; the distance between the roller receiver is 30 cm, and the receiving speed is 80 r / min; the injection speed is 0.2 mL / min; the translation speed is 0.5 cm / min. During electrospinning, the air humidity is controlled at 50-65%. Extract 10 mL of the spinning solution to obtain a 24*32 cm 2 covalent organic framework fiber membrane. After electrospinning, dry the fiber membrane in an oven at 60 °C for 2 h, denoted as PAN / COF-2.

[0045] Photocatalytic Degradation Experiment of Tetracycline in Water by Covalent Organic Framework Fiber Membrane: Cut a 11*11 cm fiber membrane and fix it in an acrylic reaction cell. Add 100 mL of 10 ppm tetracycline solution to the reaction cell. Under the irradiation of a xenon lamp with 1000 W / m 2, under the irradiation of a xenon lamp with λ > 420 nm, 1 mL of the sample was taken from the reaction cell after 0, 2, 5, 10, 15, 30, 45, and 60 min, and its residual tetracycline concentration was detected by high performance liquid chromatography.

[0046] Example 3: This example is another exemplary method for preparing a covalent organic framework fiber membrane. Different from Example 1, the casting agent used is different, and it includes:

[0047] Weigh 29.8 mg of 5,5',5'',5'''-(pyrene-1,3,6,8-tetraphenyl)tetrapyridine aldehyde and 22.8 mg of 4,4'-biphenyldicarbonitrile and place them in a glass bottle. Add 1 mL of o-dichlorobenzene and 1 mL of n-butanol, and ultrasonically treat for 5 min to disperse them evenly. After ultrasonic treatment, add 0.2 mL of 5 mol / L 1,8-diazabicyclo[5,4,0]undec-7-ene aqueous solution to catalyze the reaction. The glass bottle was subjected to vacuum freeze degassing through three cycles of liquid nitrogen freezing-thawing to prevent the generation of other by-products caused by excessive oxidation reactions. The sealed glass bottle was placed in an oven at 120 °C for reaction for 72 h to form a covalent organic framework through the Knoevenagel condensation reaction. After the reaction, the solid product in the glass bottle was obtained by suction filtration, washed with tetrahydrofuran until the washing liquid was colorless, and dried in an oven at 60 °C to obtain the COF photocatalyst, denoted as COF-1. Add 5 wt% of the COF photocatalyst and 12 wt% of polyvinylidene fluoride to a beaker, and then add 20 mL of N,N-diethylacetamide, and stir at a speed of 400 r / min for 12 h to make the spinning solution evenly dispersed. Then electrospinning was carried out, with the high voltage set at 25 KV and the low voltage at 0.25 kV; the receiving distance of the roller was 30 cm, and the receiving speed was 80 r / min; the injection speed was 0.2 mL / min; the translation speed was 0.5 cm / min. During electrospinning, the air humidity was controlled at 50 - 65%. Extract 10 mL of the spinning solution to obtain a 2 covalent organic framework fiber membrane of 24 * 32 cm. After spinning, the fiber membrane was dried in an oven at 60 °C for 2 h, denoted as PVDF / COF-1.

[0048] Photocatalytic degradation experiment of tetracycline in water by the covalent organic framework fiber membrane: Cut a 11 * 11 cm fiber membrane and fix it in an acrylic reaction cell. Add 100 mL of 10 ppm tetracycline solution to the reaction cell, and under the irradiation of a xenon lamp with 1000 W / m 2 , λ > 420 nm, 1 mL of the sample was taken from the reaction cell after 0, 2, 5, 10, 15, 30, 45, and 60 min, and its residual tetracycline concentration was detected by high performance liquid chromatography.

[0049] As Figure 3As shown, it can be clearly observed that the COF photocatalyst prepared in Example 1 has a rod-like structure, with a complete morphology and high crystallinity. As Figure 4 shown, the fibrous structure of the membrane can be clearly observed. There is no large-scale material structure on the surface of the covalent organic framework fiber membrane of Example 1, indicating that the COF is evenly dispersed in the nanofiber membrane.

[0050] As Figure 5 shown, it can be seen that the COF nanofiber membrane of Example 1 completely absorbs water droplets within 200 ms, indicating good water absorption performance, which provides convenient conditions for sufficient contact and reaction with antibiotic sewage.

[0051] Figure 6 is the water contact angle change diagram of the covalent organic framework fiber membrane of Example 3. As time goes by, PVDF / COF-1 hardly absorbs water, indicating that the nanofiber membrane has strong hydrophobicity, which may be related to its low photocatalytic efficiency.

[0052] Figure 7 is the degradation activity diagram of the covalent organic framework fiber membranes of Examples 1-3 for tetracycline. Among them, the covalent organic framework fiber membrane in Example 1 has good degradation activity for tetracycline and achieves complete removal in 10 min.

[0053] Verification Example 1: Degradation effect on different antibiotic pollutants;

[0054] Tetracycline (TC), levofloxacin (LVX), acid orange 7 (AO7), and phenol were used as antibiotic pollutants at the same concentration respectively. The covalent organic framework fiber membrane of Example 1 was used, and the covalent organic framework fiber membrane was used to catalyze the degradation of antibiotics with reference to Example 1. Samples were taken from each reaction pool at different time points to detect the residual concentrations of different antibiotic pollutants.

[0055] From Figure 1 it can be seen that the covalent organic framework fiber membrane of Example 1 has good degradation effects on several typical and commonly used antibiotics, indicating that the covalent organic framework fiber membrane of the present invention has universality in the treatment of water body antibiotic pollution.

[0056] Verification Example 2: Degradation effect of tetracycline after multiple reuse;

[0057] Tetracycline (TC) was used as the antibiotic pollutant, and the covalent organic framework fiber membrane of Example 1 was used. The condition was natural light. The covalent organic framework fiber membrane was used to catalyze the degradation of antibiotics with reference to Example 1. After each use, the covalent organic framework fiber membrane was regenerated and then used again for the tetracycline degradation experiment, and the degradation efficiency after multiple reuse was recorded.

[0058] From Figure 2It can be seen that the covalent organic framework fiber membrane in Example 1 achieved a 100% tetracycline removal rate within 90 minutes and could also achieve good antibiotic degradation efficiency under natural light conditions. In the continuous flow reaction, the covalent organic framework fiber membrane of the present invention can treat 60 L·m -2 ·day -1 , providing support for industrial practical applications.

[0059] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. Application of a covalent organic framework fiber membrane in catalytic degradation of antibiotics, characterized in that, Including: (1) Thoroughly mix an organic ligand with an aldehyde - terminal group and an organic ligand with a cyano - terminal group evenly. Add o - dichlorobenzene, n - butanol, and an aqueous solution of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene for mixing. After the mixed solution is degassed by vacuum freezing three times, seal the bottle mouth and carry out the Knoevenagel condensation reaction to obtain a functional COF photocatalyst; (2) Uniformly disperse the functional COF photocatalyst in a casting agent and an organic solvent, stir at a rotation speed of 400 - 600 r / min until the solution is uniform and particle - free to obtain a spinning solution for electrospinning. After electrospinning, dry it to obtain a covalent organic framework fiber membrane. Add an aqueous solution containing antibiotic pollutants to the reaction pool, fix the covalent organic framework fiber membrane in the reaction pool, and carry out a photocatalytic reaction under light conditions. During this period, sample from the reaction pool to monitor the residual concentration of pollutants; The casting agent is one of polyacrylonitrile and polyvinylidene fluoride; the organic ligand with an aldehyde - terminal group is one of 1,3,6,8 - tetra(4 - formylphenyl)pyrene, 5,5',5'',5'''-(pyrene - 1,3,6,8 - tetraphenyl)tetrapyridine aldehyde, and N,N,N',N'-tetra(4 - formylphenyl)-1,4 - benzenediamine; the organic ligand with a cyano - terminal group is one of 2,2 - bipyridine - 5,5 - dicarbonitrile, terephthalonitrile, and 4,4'-biphenyldicarbonitrile; In the spinning solution, the concentration of the functional COF photocatalyst is 5 - 15 wt%, and the concentration of the casting agent is 10 - 20 wt%; The molar ratio of the organic ligand with an aldehyde - terminal group to the organic ligand with a cyano - terminal group is (1 - 3):(2 - 4); The concentration of the aqueous solution of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene is 1 - 5 mol / L, and the volume ratio of o - dichlorobenzene, n - butanol, and the aqueous solution of 1,8 - diazabicyclo[5.4.0]undec - 7 - ene is (0.5 - 2):(0.5 - 2):(0.1 - 0.5); The organic solvent is one or more of N,N - dimethylformamide, N,N - dimethylacetamide, and acetone; The parameters of the electrospinning are: high voltage 15 - 25 kV, low voltage 0.25 kV; drum receiving distance 30 cm, receiving speed 80 - 100 r / min; injection speed 0.2 - 0.5 mL / min; electrospinning machine translation speed 500 mm / min; during electrospinning, the air humidity is controlled at 50 - 65%; 5 - 10 mL of spinning solution is used for each electrospinning; the drying temperature after electrospinning is 60 - 70°C.

2. The application of the covalent organic framework fiber membrane according to claim 1 in the catalytic degradation of antibiotics, characterized in that, The antibiotic is one or more of sulfamethoxazole, levofloxacin, norfloxacin, and tetracycline.

3. The application of the covalent organic framework fiber membrane according to claim 1 in the catalytic degradation of antibiotics, characterized in that, The illumination condition is one of natural sunlight, a xenon lamp with 1000 W / m 2 , λ > 420 nm, and an LED lamp. No additional oxidant is added to the photocatalytic reaction, and only the dissolved oxygen in the water body is utilized.

4. The application of the covalent organic framework fiber membrane according to claim 1 in the catalytic degradation of antibiotics, characterized in that, Before carrying out the photocatalytic reaction, an adsorption process under dark conditions for 15 - 30 min is carried out.

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