A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst.

Abstract

This invention discloses a method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst. The method involves treating antibiotic wastewater using this photocatalyst. The preparation of the thiourea-based covalent organic framework photocatalyst includes the following steps: mixing 1,4-phenylene di(thiourea), benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde, an organic solvent, and an acid catalyst, and then performing a condensation reaction to obtain the thiourea-based covalent organic framework photocatalyst. This method has advantages such as good degradation effect, rapid degradation, convenient operation, simple steps, low cost, and no secondary pollution. It is a widely applicable method that can efficiently and thoroughly remove antibiotics from water. For example, norfloxacin can be 100% removed within 60 minutes.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic treatment of antibiotic wastewater, specifically relating to a method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst. Background Technology

[0002] With the development of industry and agriculture, large amounts of antibiotic wastewater are discharged into the aquatic environment, polluting the water environment and seriously endangering human health. Water pollution control has become a global challenge, and antibiotic wastewater, as a recalcitrant form of wastewater, has always been a hot research topic. Traditional wastewater treatment processes generally suffer from drawbacks such as high cost, slow reaction time, easy secondary pollution, and difficulty in treating low-concentration wastewater. In contrast, photocatalytic degradation technology has advantages such as ease of operation, low cost, high efficiency, and no secondary pollution, making it highly promising for degrading pollutants.

[0003] Covalent organic frameworks (COFs) are crystalline network materials composed of strong covalent bonds of symmetrical organic molecules. These materials possess advantages such as large specific surface area, low framework density, high porosity, controllable physicochemical properties, easy functionalization, and diverse synthesis strategies. COFs have demonstrated excellent performance in numerous fields, including heterogeneous catalysis, energy storage, sensing, adsorption, membrane separation, and biotherapy, and have experienced rapid development in the past decade. However, to date, reports on the application of COF materials in the photocatalytic degradation of antibiotics are still scarce. Furthermore, existing imine-bonded COFs suffer from poor charge separation efficiency, low conductivity, and chemical instability, which significantly limits their application in the photocatalytic degradation of antibiotics in water. Therefore, finding a covalent organic framework photocatalyst with high catalytic activity, stable physicochemical properties, and broad applicability is of great significance and an urgent need for the effective removal of antibiotics from water. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, which has good degradation effect, rapid degradation, convenient operation, simple steps, low cost, and no secondary pollution.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0006] A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, wherein the method utilizes the thiourea-based covalent organic framework photocatalyst to degrade antibiotic wastewater; the preparation method of the thiourea-based covalent organic framework photocatalyst includes the following steps: mixing 1,4-phenylene di(thiourea), benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde, an organic solvent and an acid catalyst, and carrying out a condensation reaction to obtain the thiourea-based covalent organic framework photocatalyst.

[0007] In a further improvement to the above method, the ratio of 1,4-phenylene di(thiourea), benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde, organic solvent, and acid catalyst is 34 mg:33 mg:1 mL:0.1 mL.

[0008] In a further improvement to the above method, the organic solvent is a mixed solvent of o-dichlorobenzene and N-methyl-2-pyrrolidone, wherein the volume ratio of o-dichlorobenzene to N-methyl-2-pyrrolidone in the mixed solvent is 1:1, and the acid catalyst is acetic acid.

[0009] In a further improvement to the above method, the temperature of the condensation reaction is 120°C and the time of the condensation reaction is 72 hours.

[0010] The above method is further improved by including the following treatment after mixing: freezing-pumping-thawing degassing of the mixed solution and vacuum sealing.

[0011] The above method is further improved by including the following treatment after the condensation reaction: washing, filtering and drying the reaction product; the washing is performed by washing three times with tetrahydrofuran and acetone respectively; the filtration is performed using a 0.22μm organic filter membrane; the drying is carried out under vacuum conditions; the drying temperature is 80℃; and the drying time is 24h.

[0012] A further improvement to the above method is that the degradation treatment involves mixing a thiourea-based covalent organic framework photocatalyst with antibiotic wastewater, stirring, and then carrying out a photocatalytic reaction under light conditions to complete the degradation of antibiotics in the water.

[0013] In a further improvement to the above method, the ratio of the thiourea-based covalent organic framework photocatalyst to antibiotic wastewater is 0.1g to 0.2g: 1L.

[0014] In a further improvement to the above method, the initial concentration of antibiotics in the antibiotic wastewater is 5 mg / L to 10 mg / L, the initial pH value of the antibiotic wastewater is 3 to 9, and the antibiotics in the antibiotic wastewater are at least one of norfloxacin, bisphenol A, and acetaminophen.

[0015] In a further improvement to the above method, the stirring is carried out in the dark, the stirring speed is 300 r / min to 400 r / min, the stirring time is 0.5 h to 1 h, and the photocatalytic reaction time is ≥ 1 h.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] (1) In view of the shortcomings of existing covalent organic framework photocatalysts, such as poor charge separation efficiency, low conductivity, and unstable chemical properties, and the resulting low degradation rate of antibiotics in water, this invention creatively proposes a method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst. The thiourea-based covalent organic framework photocatalyst (Bpt-COF) is prepared by an imine condensation reaction of 1,4-phenylene di(thiourea) and benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde (BTT). Compared with other covalent organic framework photocatalysts (Bab-COF, Bpd-COF), the thiourea-based covalent organic framework photocatalyst prepared in this invention has the following advantages: (a) It has raised "sea urchin-like" burrs, which can increase the site contact with pollutants and is beneficial to photocatalytic degradation; (b) It has strong absorption capacity and narrower optical band gap in the visible light range. Since the size of the optical band gap mainly affects the generation and transport of photogenerated charges and the generation of active species, a narrower optical band gap makes it easier to be excited to form electrons and holes and generate more active species, which is beneficial to improving the photocatalytic activity of the photocatalyst. At the same time, due to its stronger absorption capacity of visible light, it can absorb more sunlight, thereby improving the photocatalytic activity of the photocatalyst while improving the light energy utilization rate; (c) It has thiourea groups, which can enhance charge separation and enhance the effect of charge carriers, which is beneficial to improving the photocatalytic activity of the photocatalyst; (d) It has higher crystallinity, which is beneficial to improving the photocatalytic activity of the photocatalyst. Based on this, when the thiourea-based covalent organic framework photocatalyst prepared in this invention is used for the catalytic degradation of antibiotics in water, it can efficiently and thoroughly remove antibiotics from the water. Taking norfloxacin as an example, the method of this invention can achieve 100% removal of norfloxacin within 60 minutes. The photocatalytic degradation effect is significant, and it has the advantages of good degradation effect, rapid degradation, convenient operation, simple steps, low cost, and no secondary pollution. It is a widely applicable method that can efficiently and thoroughly remove antibiotics from water, and has high application and commercial value.

[0018] (2) In this invention, the method for preparing thiourea-based covalent organic framework photocatalysts can precisely control the nucleation and growth rates during the reaction process by optimizing the amounts of each raw material and the conditions of the condensation reaction, thereby achieving high-quality covalent organic framework crystals. In particular, even slight changes to the above conditions may result in the inability to obtain the corresponding thiourea-based covalent organic framework crystal structure.

[0019] (3) The method of the present invention uses a thiourea-based covalent organic framework photocatalyst, which is synthesized by forming the same imine linkage bond between 1,4-phenylene di(thiourea) and benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde. It is a fluffy powdery solid with pores distributed between micropores. It has the advantages of good adsorption performance, high catalytic activity, stable physicochemical properties, and wide applicability. It can also remain stable under high temperature, strong acid and strong alkali conditions, and has high practicality. Attached Figure Description

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0021] Figure 1 The images shown are SEM images of the covalent organic framework photocatalyst (Bab-COF), covalent organic framework photocatalyst (Bpd-COF), and thiourea-based covalent organic framework photocatalyst (Bpt-COF) in Example 1 of this invention, where (a) is Bab-COF, (b) is Bpd-COF, and (c) is Bpt-COF.

[0022] Figure 2 The images show the UV-Vis diffuse reflectance and optical bandgap diagrams of the covalent organic framework photocatalyst (Bab-COF), covalent organic framework photocatalyst (Bpd-COF), and thiourea-based covalent organic framework photocatalyst (Bpt-COF) in Example 1 of this invention, where (a) is the UV-Vis diffuse reflectance diagram and (b) is the optical bandgap diagram.

[0023] Figure 3 The XRD diffraction patterns of the covalent organic framework photocatalyst (Bab-COF), covalent organic framework photocatalyst (Bpd-COF), and thiourea-based covalent organic framework photocatalyst (Bpt-COF) in Example 1 of this invention are shown, where (a) is Bab-COF, (b) is Bpd-COF, and (c) is Bpt-COF.

[0024] Figure 4 The images show the fluorescence and photoluminescence spectra of the covalent organic framework photocatalyst (Bpd-COF) and the thiourea-based covalent organic framework photocatalyst (Bpt-COF) in Example 1 of this invention.

[0025] Figure 5 The graph shows the degradation effect of norfloxacin on covalent organic framework photocatalysts (Bab-COF), (Bpd-COF), and thiourea-based covalent organic framework photocatalysts (Bpt-COF) in Example 1 of this invention.

[0026] Figure 6The graph shows the degradation effect of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) on norfloxacin under different pH conditions in Example 2 of this invention.

[0027] Figure 7 The graph shows the degradation effect of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) on norfloxacin under the action of different organic matter in Example 3 of this invention.

[0028] Figure 8 The graph shows the degradation effect of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) on norfloxacin under different concentrations of organic matter in Example 4 of this invention. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0030] Example 1:

[0031] A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, specifically involving the degradation treatment of norfloxacin wastewater using a thiourea-based covalent organic framework photocatalyst, includes the following steps:

[0032] Weigh 6 mg of thiourea-based covalent organic framework photocatalyst (Bpt-COF) and add it to 60 mL of norfloxacin solution with a concentration of 5 mg / L and pH = 7.51. Stir magnetically at 400 r / min for 1 h in the dark to reach adsorption equilibrium. Then turn on the light source and irradiate under simulated sunlight (visible light with λ ≥ 420 nm) for 1 h to complete the degradation of norfloxacin in the water.

[0033] Control group 1: The photocatalyst used was a covalent organic framework photocatalyst (Bab-COF), and other conditions were the same.

[0034] Control group 2: The photocatalyst used was a covalent organic framework photocatalyst (Bpd-COF), and other conditions were the same.

[0035] Control group 3: The photocatalyst used was the trithiophene-based covalent organic framework photocatalyst (BTT-TPDA-COF) prepared in Example 1 of the existing patent CN114853113A, and other conditions were the same.

[0036] In this embodiment, a method for preparing a thiourea-based covalent organic framework photocatalyst (Bpt-COF) is employed, comprising the following steps:

[0037] (1) Weigh 33 mg of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde (BTT) and 34 mg of 1,4-phenylene di(thiourea) (PT) and mix them in a vacuum tube. Add 0.5 mL of o-dichlorobenzene and 0.5 mL of N-methyl-2-pyrrolidone respectively, and sonicate for 15 min to mix evenly. Then add 0.1 mL of acetic acid and sonicate for 3 min to mix evenly to obtain a mixture.

[0038] (2) The mixture in step (1) is degassed by three cycles of freezing-pumping-thawing. That is, after freezing it with liquid nitrogen, the gas in the frozen mixture is sucked out by an oil pump, and then thawing is performed. This process is repeated 3 times. Then, after vacuum sealing, it is heated at 120°C for 72 hours, and then taken out and cooled.

[0039] (3) The reaction product in step (2) was washed three times with tetrahydrofuran and acetone (10 mL each time), filtered with a 0.22 μm organic filter membrane, and then dried at 80 °C for 24 h under vacuum to obtain a thiourea-based covalent organic framework photocatalyst, denoted as Bpt-COF.

[0040] In this embodiment, the preparation method of the covalent organic framework photocatalyst (Bab-COF) includes the following steps:

[0041] (1) Weigh 33 mg of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde (BTT) and 16.2 mg of p-phenylenediamine (AB) and mix them in a vacuum tube. Add 1.5 mL of o-dichlorobenzene and 1.5 mL of n-butanol respectively, and sonicate for 3 min to mix evenly. Then add 0.15 mL of acetic acid and sonicate for 3 min to mix evenly to obtain a mixture.

[0042] (2) The mixture in step (1) was degassed by three cycles of freezing-pumping-thawing, vacuum sealed, heated at 120°C for 72 hours, and then taken out and cooled.

[0043] (3) The reaction product in step (2) was washed three times with tetrahydrofuran (10 mL each time), filtered with a 0.22 μm organic filter membrane, and then dried at 120 °C for 12 h under vacuum to obtain a covalent organic framework photocatalyst, denoted as Bab-COF.

[0044] In this embodiment, the preparation method of the covalent organic framework photocatalyst (Bpd-COF) includes the following steps:

[0045] (1) Weigh 33 mg of benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde (BTT) and 29.1 mg of 1,1'-(1,4-phenylene)diurea (PD) and mix them in a vacuum tube. Add 0.5 mL of o-dichlorobenzene and 0.5 mL of N-methyl-2-pyrrolidone respectively, and sonicate for 15 min to mix evenly. Then add 0.1 mL of acetic acid and sonicate for 3 min to mix evenly to obtain a mixture.

[0046] (2) The mixture in step (1) was degassed by three cycles of freezing-pumping-thawing, vacuum sealed, heated at 120°C for 72 hours, and then taken out and cooled.

[0047] (3) The reaction product in step (2) was washed three times with tetrahydrofuran and acetone (10 mL each time), filtered with a 0.22 μm organic filter membrane, and then dried at 80 °C for 24 h under vacuum to obtain a covalent organic framework photocatalyst, denoted as Bpd-COF.

[0048] During the magnetic stirring and photocatalysis process, 1 mL of sample was taken at regular intervals and filtered through a 0.22 μm filter. The absorbance of the filtrate was measured by liquid chromatography to determine the antibiotic concentration after adsorption and after light irradiation. This allowed us to obtain the adsorption effect and photocatalytic degradation effect of imine covalent organic framework materials with different imine functions on norfloxacin.

[0049] Figure 1 The images shown are SEM images of the covalent organic framework photocatalyst (Bab-COF), covalent organic framework photocatalyst (Bpd-COF), and thiourea-based covalent organic framework photocatalyst (Bpt-COF) from Example 1 of this invention, where (a) is Bab-COF, (b) is Bpd-COF, and (c) is Bpt-COF. Figure 1 It is evident that all three covalent organic framework materials possess a typical dendritic structure. Compared to Bab-COF and Bpd-COF, the raised "urchin-like" burrs of Bpt-COF increase the site contact with pollutants, which is beneficial for photocatalytic degradation.

[0050] Figure 2 The images show the UV-Vis diffuse reflectance and optical bandgap diagrams of the covalent organic framework photocatalysts (Bab-COF), (Bpd-COF), and (Bpt-COF) thiourea-based covalent organic framework photocatalysts in Example 1 of this invention, where (a) is the UV-Vis diffuse reflectance diagram and (b) is the optical bandgap diagram. Figure 2As can be seen, compared with Bab-COF and Bpd-COF, the thiourea-based covalent organic framework photocatalyst (Bpt-COF) of the present invention has a strong absorption capacity and a narrower optical band gap in the visible light range, and is more easily excited to form electrons and holes, thereby improving the photocatalytic performance and light energy utilization rate of the photocatalyst under visible light.

[0051] Figure 3 The images show the XRD diffraction patterns of the covalent organic framework photocatalyst (Bab-COF), covalent organic framework photocatalyst (Bpd-COF), and thiourea-based covalent organic framework photocatalyst (Bpt-COF) in Example 1 of this invention, where (a) is Bab-COF, (b) is Bpd-COF, and (c) is Bpt-COF. Figure 3 It can be seen that all three covalent organic framework materials contain the characteristic peak (100) of covalent organic frameworks, which is consistent with the crystal structure of COFs materials, indicating that the main body of these three materials is a covalent organic framework.

[0052] Figure 4 The images show the fluorescence and photoluminescence spectra of the covalent organic framework photocatalyst (Bpd-COF) and the thiourea-based covalent organic framework photocatalyst (Bpt-COF) in Example 1 of this invention. Figure 4 It can be seen that Bpt-COF shows a weaker fluorescence signal compared with Bpd-COF, which indicates that the introduction of thiourea groups on the imine bond can enhance charge separation and enhance the effect of charge carriers.

[0053] Figure 5 The images show the degradation effects of norfloxacin on covalent organic framework photocatalysts (Bab-COF), (Bpd-COF), and thiourea-based covalent organic framework photocatalysts (Bpt-COF) in Example 1 of this invention. Figure 5It was found that after 1 hour of dark reaction adsorption and 1 hour of light irradiation, the removal rates of norfloxacin by Bab-COF, Bpd-COF, and Bpt-COF were 49.9%, 75.1%, and 100.0%, respectively. Furthermore, the degradation effect of the trithienyl covalent organic framework photocatalyst (BTT-TPDA-COF) on norfloxacin was compared; BTT-TPDA-COF only achieved a removal rate of 80% for norfloxacin within 2 hours. Therefore, compared to the pure imine-bonded covalent organic framework material (Bab-COF) and the trithienyl covalent organic framework photocatalyst (BTT-TPDA-COF), the functional groups grafted onto imine bonds (Bpd-COF) and thiourea (Bpt-COF) are more effective in degrading the antibiotic norfloxacin. This is because the introduction of functional groups can break the exciton effect between imine bonds, regulate the polarization properties between the imine bonds and the building blocks, and further regulate the transport of charge carriers. Furthermore, among Bab-COF, Bpd-COF, and Bpt-COF, the thiourea-based covalent organic framework (Bpt-COF) exhibits the narrowest optical bandgap and demonstrates better photocatalytic activity, followed by Bpd-COF, with Bab-COF showing the weakest. The thiourea-based covalent organic framework photocatalyst of this invention exhibits the narrowest optical bandgap, the weakest fluorescence intensity, the most effective charge separation, and the best photocatalytic degradation effect.

[0054] Therefore, the photocatalytic degradation ability of antibiotics by different imine-functionalized covalent organic framework materials increases with narrowing of the optical band gap. In particular, the thiourea-based covalent organic framework photocatalyst (Bpt-COF) of the present invention has the narrowest band gap, which is more conducive to the material being excited by visible light and generating more photogenerated charges. This is more conducive to the transport and separation of photogenerated charge carriers, and greatly improves the photocatalytic effect of the material.

[0055] Example 2:

[0056] A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, specifically involving the degradation treatment of norfloxacin wastewater using a thiourea-based covalent organic framework photocatalyst, includes the following steps:

[0057] Four portions of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) prepared in Example 1, each 6 mg, were weighed and added to norfloxacin solutions with pH values ​​of 3, 5, 7, and 9 (the solution volume was 60 mL and the concentration was 5 mg / L). The solutions were magnetically stirred at 400 r / min for 1 h in the dark to reach adsorption equilibrium. Then, the light source was turned on and the solution was irradiated under simulated sunlight (visible light with λ≥420 nm) for 1 h to carry out the photocatalytic reaction and complete the degradation of norfloxacin in the water.

[0058] During the magnetic stirring and photocatalysis process, 1 mL of sample was taken every 15 min and filtered through a 0.22 μm filter. The filtrate was then analyzed by liquid chromatography to determine the antibiotic concentration after adsorption and after light irradiation, thereby obtaining the adsorption effect and photocatalytic degradation effect of Bpt-COF on norfloxacin.

[0059] Figure 6 This image shows the degradation effect of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) on norfloxacin under different pH conditions in Example 2 of this invention. Figure 6 It is known that the thiourea covalent organic framework photocatalyst (Bpt-COF) of the present invention achieves removal rates of 84.1%, 100.0%, 100%, and 100% for norfloxacin at pH values ​​of 3, 5, 7, and 9, respectively. pH value affects the charge of the material and the form in which norfloxacin exists. Different pH values ​​result in different surface charge properties of Bpt-COF based on its zeta potential, thus affecting the mutual adsorption of norfloxacin onto the Bpt-COF surface. The thiourea-based covalent organic framework photocatalyst (Bpt-COF) prepared in this invention exhibits excellent degradation performance at pH values ​​from 3 to 9. In particular, it shows better degradation performance for antibiotic wastewater at pH values ​​from 5 to 9, indicating that the thiourea-based covalent organic framework photocatalyst (Bpt-COF) of the present invention possesses strong stability and excellent adaptability.

[0060] Example 3:

[0061] A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, specifically involving the degradation treatment of norfloxacin wastewater using a thiourea-based covalent organic framework photocatalyst, includes the following steps:

[0062] Four portions of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) prepared in Example 1, each 6 mg, were weighed and added to four 60 mL portions of norfloxacin solution with a concentration of 5 mg / L and pH = 7.51. The mixture was then thoroughly dispersed. The nutrient source influencing factors in the solution were 5 mg / L of humic acid (HA), fulvic acid (FA), and sodium humate (HA-Na). The mixture was magnetically stirred at 400 r / min for 1 h under dark conditions to reach adsorption equilibrium. Then, the light source was turned on, and the mixture was irradiated under simulated sunlight (visible light with λ ≥ 420 nm) for 1 h to complete the degradation of norfloxacin in the water.

[0063] During the magnetic stirring and photocatalysis process, 1 mL of sample was taken every 15 min and filtered using a 0.22 μm filter. The filtrate was then analyzed by liquid chromatography to determine the antibiotic concentration after adsorption and after light irradiation, thereby obtaining the photocatalytic degradation effect of Bpt-COF on norfloxacin.

[0064] Figure 7 This image shows the degradation effect of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) on norfloxacin under the action of different organic matter in Example 3 of this invention. Figure 7 It can be seen that under the action of different organic matter, the removal rate of norfloxacin by the thiourea-based covalent organic framework photocatalyst (Bpt-COF) reached 100%. This indicates that the presence of organic matter has little effect on the photocatalytic degradation of norfloxacin by the thiourea-based covalent organic framework photocatalyst (Bpt-COF).

[0065] Example 4:

[0066] A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, specifically involving the degradation treatment of norfloxacin wastewater using a thiourea-based covalent organic framework photocatalyst, includes the following steps:

[0067] Four portions of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) prepared in Example 1, each 6 mg, were weighed and added to four 60 mL portions of norfloxacin solution with a concentration of 5 mg / L and pH = 7.51. The solutions contained nutrient source influencing factors at concentrations of 0 mg / L, 2.5 mg / L, 5 mg / L, and 10 mg / L sodium humate (HA-Na), respectively. The mixture was magnetically stirred at 400 r / min for 1 h in the dark to reach adsorption equilibrium. Then, the light source was turned on, and the mixture was irradiated under simulated sunlight (visible light with λ ≥ 420 nm) for 1 h to complete the degradation of norfloxacin in the water.

[0068] During the magnetic stirring and photocatalysis process, 1 mL of sample was taken every 15 min and filtered using a 0.22 μm filter. The filtrate was then analyzed by liquid chromatography to determine the antibiotic concentration after adsorption and after light irradiation, thereby obtaining the photocatalytic degradation effect of Bpt-COF on norfloxacin.

[0069] Figure 8 This image shows the degradation effect of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) on norfloxacin under different concentrations of organic matter in Example 4 of this invention. Figure 8 It can be seen that under different concentrations of organic matter, the removal rates of norfloxacin by the thiourea-based covalent organic framework photocatalyst (Bpt-COF) were 100%, 100%, 100%, and 95%, respectively. This demonstrates that the thiourea-based covalent organic framework photocatalyst (Bpt-COF) of this invention exhibits strong stability and excellent adaptability under organic matter conditions.

[0070] Example 5:

[0071] A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, specifically involving the degradation treatment of bisphenol A and acetaminophen wastewater using a thiourea-based covalent organic framework photocatalyst, includes the following steps:

[0072] Two portions of the thiourea-based covalent organic framework photocatalyst (Bpt-COF) prepared in Example 1, each 6 mg, were weighed and added to bisphenol A (BPA) solution and acetaminophen (ACE) solution (the volume of these solutions was 60 mL, the concentration was 5 mg / L, and the pH was 6.5), respectively. The mixture was stirred magnetically at 400 r / min for 1 h in the dark to reach adsorption equilibrium. Then, the light source was turned on, and the photocatalytic reaction was carried out under simulated sunlight (visible light with λ≥420 nm) for 1 h to complete the degradation of norfloxacin in the water.

[0073] During the magnetic stirring and photocatalysis process, 1 mL of sample was taken every 15 min and filtered using a 0.22 μm filter. The filtrate was then analyzed by liquid chromatography to determine the antibiotic concentrations after adsorption and after light irradiation, thus obtaining the photocatalytic degradation effect of Bpt-COF on various antibiotics.

[0074] The tests showed that after 1 hour of photocatalytic reaction, the thiourea-based covalent organic framework photocatalyst (Bpt-COF) achieved a 100% removal rate for both bisphenol A (BPA) and acetaminophen (ACE). This demonstrates that the thiourea-based covalent organic framework photocatalyst (Bpt-COF) of this invention exhibits highly efficient and thorough degradation effects on various antibiotics.

[0075] The results above show that, compared with other covalent organic framework photocatalysts (Bab-COF, Bpd-COF), the thiourea-based covalent organic framework photocatalyst prepared in this invention has the following advantages: (a) It has raised "sea urchin-like" burrs, which can increase the site contact with pollutants and is beneficial to photocatalytic degradation; (b) It has strong absorption capacity and a narrower optical band gap in the visible light range. Since the size of the optical band gap mainly affects the generation and transport of photogenerated charges and the generation of active species, a narrower optical band gap makes it easier to be excited to form electrons and holes and generate more active species, which is beneficial to improving the photocatalytic activity of the photocatalyst. At the same time, due to its stronger absorption capacity of visible light, it can absorb more sunlight, thereby improving the photocatalytic activity of the photocatalyst while improving the light energy utilization rate; (c) It has thiourea groups, which can enhance charge separation and enhance the effect of charge carriers, which is beneficial to improving the photocatalytic activity of the photocatalyst; (d) It has higher crystallinity, which is beneficial to improving the photocatalytic activity of the photocatalyst. Meanwhile, when the thiourea-based covalent organic framework photocatalyst prepared in this invention is used for the catalytic degradation of antibiotics in water, it can efficiently and thoroughly remove antibiotics from the water. It has the advantages of good degradation effect, rapid degradation, convenient operation, simple steps, low cost, and no secondary pollution. It is a widely applicable method that can efficiently and thoroughly remove antibiotics from water, and has high application and commercial value.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst, characterized in that, The method described herein utilizes a thiourea-based covalent organic framework photocatalyst to degrade antibiotic wastewater. The preparation method of the thiourea-based covalent organic framework photocatalyst includes the following steps: mixing 1,4-phenylene di(thiourea), benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde, an organic solvent, and an acid catalyst, and performing a condensation reaction to obtain the thiourea-based covalent organic framework photocatalyst; the ratio of 1,4-phenylene di(thiourea), benzo[1,2-b:3,4-b':5,6-b']trithiophene-2,5,8-trialdehyde, the organic solvent, and the acid catalyst is 34 mg:33 mg:1 mL:0.1 mL; the condensation reaction temperature is 120°C, and the condensation reaction time is 72 h.

2. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to claim 1, characterized in that, The organic solvent is a mixed solvent of o-dichlorobenzene and N-methyl-2-pyrrolidone, wherein the volume ratio of o-dichlorobenzene to N-methyl-2-pyrrolidone in the mixed solvent is 1:1, and the acid catalyst is acetic acid.

3. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to claim 2, characterized in that, The mixing process also includes the following steps: freezing-pumping-thawing the mixed solution for degassing, followed by vacuum sealing.

4. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to claim 3, characterized in that, The condensation reaction is followed by the following treatments: washing, filtering, and drying the reaction product; the washing is performed by washing three times with tetrahydrofuran and acetone respectively; the filtration is performed using a 0.22μm organic filter membrane; the drying is carried out under vacuum conditions; the drying temperature is 80℃; and the drying time is 24h.

5. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to any one of claims 1 to 4, characterized in that, The degradation process involves mixing a thiourea-based covalent organic framework photocatalyst with antibiotic wastewater, stirring, and then conducting a photocatalytic reaction under light conditions to complete the degradation of antibiotics in the water.

6. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to claim 5, characterized in that, The ratio of the thiourea-based covalent organic framework photocatalyst to antibiotic wastewater is 0.1g~0.2g∶1L.

7. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to claim 6, characterized in that, The initial concentration of antibiotics in the antibiotic wastewater is 5 mg / L to 10 mg / L, the initial pH value of the antibiotic wastewater is 3 to 9, and the antibiotics in the antibiotic wastewater are at least one of norfloxacin, bisphenol A, and acetaminophen.

8. The method for degrading antibiotics in water using a thiourea-based covalent organic framework photocatalyst according to claim 7, characterized in that, The stirring is carried out in the dark, the stirring speed is 300 r / min to 400 r / min, the stirring time is 0.5 h to 1 h, and the photocatalytic reaction time is ≥1 h.

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