Method for treating organic pollutant wastewater by using spacer covalent organic framework

Abstract

The invention discloses a method for treating organic pollutant wastewater by using a spacer covalent organic framework, which is used for degrading organic pollutants in wastewater by using the spacer covalent organic framework as a photocatalyst. Wherein the spacer covalent organic framework is at least one of an olefin spacer covalent organic framework, an alkyl spacer covalent organic framework and a benzene ring spacer covalent organic framework. According to the method for treating the organic pollutant wastewater by utilizing the spacer covalent organic framework, a pollutant degradation system which is efficient, high in selectivity and excellent in stability can be constructed under the action of the spacer covalent organic framework, so that the organic pollutants in the wastewater can be efficiently degraded; the method is particularly suitable for wastewater treatment and degradation of persistent organic pollutants, has the advantages of simple process, convenience in operation, low cost, high degradation efficiency, good degradation effect, good adaptability and the like, and is an efficient and controllable organic pollutant photocatalytic treatment strategy.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic treatment technology for organic wastewater, and relates to a method for treating organic pollutant wastewater using a spacer-based covalent organic framework. Background Technology

[0002] The increasing discharge of various organic pollutants into water bodies poses a serious threat to ecosystems and human health. At the same time, due to the complex structure and high stability of organic pollutants, they are difficult to degrade naturally in the environment, which has become a long-standing problem in the field of environmental governance.

[0003] In recent years, photocatalysis technology has attracted widespread attention as an environmentally friendly method for treating pollutants due to its simple operation, mild conditions, and high degradation efficiency. In photocatalytic reactions, superoxide radicals (·O2)... - ) and singlet oxygen ( 1 O2) are two important bioactive species. - It has a strong reducing ability and can quickly destroy the molecular structure of organic pollutants, but its reaction selectivity is poor and there are many side reactions. 1 O2, as a non-radical species, while possessing relatively mild oxidizing power, exhibits better selectivity, enabling the targeted degradation of certain pollutants. However, current technologies rely heavily on O2 alone. - or 1 O2 has significant limitations. Therefore, how to achieve O2 in the reaction system is a key issue. - and 1 The regulation and synergistic effects of O2 ratios remain a key challenge that urgently needs to be addressed in the field of environmental governance.

[0004] Covalent organic frameworks (COFs) have shown great potential in the photocatalytic degradation of organic pollutants due to their high designability, porous structure, and excellent stability. However, existing COF materials... - and 1 There are still shortcomings in the regulation and synergistic utilization of O2, making it difficult to fully leverage the complementary advantages of the two.

[0005] Therefore, there is an urgent need to construct a novel covalent organic framework material to achieve O2 - and 1 The controlled generation of O2 and the construction of a highly efficient, selective, and stable pollutant treatment system will overcome the limitations of existing photocatalytic technologies and achieve efficient removal of organic pollutants. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for treating organic pollutant wastewater using a spacer-based covalent organic framework, which has high degradation efficiency, good degradation effect and good adaptability.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for treating organic pollutant wastewater using a spacer-based covalent organic framework, wherein the method uses the spacer-based covalent organic framework as a photocatalyst to degrade the organic pollutants in the wastewater; wherein the spacer-based covalent organic framework is at least one of olefin spacer-based covalent organic framework, alkyl spacer-based covalent organic framework, and benzene ring spacer-based covalent organic framework.

[0008] A further improvement to the above method is that the olefin spacer covalent organic framework is prepared by reacting 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and thieno[3,2-b]thiophene-2,5-dicarboxaldehyde as raw materials under the conditions of organic solvent and catalyst to obtain the olefin spacer covalent organic framework.

[0009] A further improvement to the above method is that the alkyl spacer covalent organic framework is prepared by reacting 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and [2,2']-bisthiophene-5,5'-dicarboxaldehyde under the conditions of organic solvent and catalyst to obtain the alkyl spacer covalent organic framework.

[0010] A further improvement to the above method is that the preparation method of the benzene ring spacer covalent organic framework uses 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxaldehyde as raw materials, and reacts them under the conditions of organic solvent and catalyst to obtain the benzene ring spacer covalent organic framework.

[0011] In a further improvement to the above method, the mass ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to thieno[3,2-b]thiophene-2,5-dicarboxaldehyde is 21.3:17.6.

[0012] In a further improvement to the above method, the mass ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and [2,2']-bisthiophene-5,5'-dicarboxaldehyde is 21.3:20.

[0013] In a further improvement to the above method, the mass ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxaldehyde is 17.7:18.5.

[0014] In a further improvement to the above method, the preparation method of the olefin spacer covalent organic framework involves the following: the mass-to-volume ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to the organic solvent is 21.3 mg:1.5 mL; the organic solvent is a mixed solution of o-dichlorobenzene and n-butanediol, with a volume ratio of o-dichlorobenzene to n-butanediol of 1:2; the mass-to-volume ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to the catalyst is 21.3 mg:0.1 mL; the catalyst is acetic acid, with a concentration of 6 M; the reaction temperature is 120 °C; and the reaction time is 72 h.

[0015] In a further improvement to the above method, the preparation method of the alkyl spacer covalent organic framework involves the following: the mass-to-volume ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to the organic solvent is 21.3 mg:1 mL; the organic solvent is a mixed solution of o-dichlorobenzene and n-butanediol, with a volume ratio of o-dichlorobenzene to n-butanediol of 3:7; the mass-to-volume ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to the catalyst is 21.3 mg:0.1 mL; the catalyst is acetic acid, with a concentration of 6 M; the reaction temperature is 120 °C; and the reaction time is 72 h.

[0016] In a further improvement to the above method, the preparation method of the benzene ring spacer covalent organic framework involves the following: the mass-to-volume ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to the organic solvent is 17.7 mg:1 mL; the organic solvent is a mixed solution of o-dichlorobenzene and n-butanediol, with a volume ratio of o-dichlorobenzene to n-butanediol of 3:7; the mass-to-volume ratio of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine to the catalyst is 21.3 mg:0.1 mL; the catalyst is acetic acid, with a concentration of 6 M; the reaction temperature is 120 °C; and the reaction time is 72 h.

[0017] The above method is further improved by using spacer-based covalent organic frameworks as photocatalysts to degrade organic pollutants in wastewater, including the following steps: mixing spacer-based covalent organic frameworks with organic pollutant wastewater, and carrying out photocatalytic reaction under light conditions to complete the degradation of organic pollutants in wastewater.

[0018] In a further improvement to the above method, the ratio of the spacer-based covalent organic framework to the organic pollutant wastewater is 0.05 g to 0.3 g: 1 L.

[0019] The above method is further improved in that the initial concentration of organic pollutants in the organic pollutant wastewater is ≤5 mg / L.

[0020] In a further improvement to the above method, the organic pollutant is at least one of acetaminophen, 2,4-dichlorophenol, p-chlorophenol, p-hydroxyanisole, and tetracycline.

[0021] In a further improvement to the above method, the initial pH value of the organic pollutant wastewater is 5 to 9.

[0022] In a further improvement to the above method, the mixing is carried out in darkness; the stirring speed is controlled at 400 r / min to 500 r / min during the mixing process, and the stirring time is 1 hour.

[0023] In a further improvement to the above method, the photocatalytic reaction time is ≥10 min.

[0024] Compared with the prior art, the advantages of the present invention are as follows: (1) Addressing the difficulty of achieving O2 in existing covalent organic framework materials - and 1 The present invention addresses the shortcomings of O2 ratio regulation and synergistic effects, leading to difficulties in constructing efficient, selective, and stable pollutant treatment systems and in efficiently and controllably degrading organic pollutants in water. It creatively proposes a method for treating organic pollutant wastewater using a spacer-based covalent organic framework (SAPP). The SAPP serves as a photocatalyst for degrading organic pollutants in the wastewater. The SAPP is at least one of olefin-based, alkyl-based, or benzene-ring-based SAPP. Compared to traditional covalent organic framework photocatalysts, the SAPP used in this invention has the following advantages: (a) It possesses a highly ordered porous structure, maintaining a large specific surface area and suitable pore size distribution, enhancing the transport efficiency of reactants and products within the SAPP, thus improving the photocatalytic degradation rate; (b) By introducing different types of spacer groups (such as olefins, alkyl groups, and benzene rings) into the framework, the electronic structure and reactive site distribution can be effectively adjusted, achieving not only efficient and controllable degradation of O2 but also... - and 1 O2 generation was controlled (the ratio of free radicals to non-free radicals was adjusted between 9.9 and 2.0), and O2 generation was achieved. - and 1The synergistic effect of O2 enables the construction of a highly efficient, selective, and stable pollutant degradation system, significantly improving the degradation efficiency and effect on organic pollutants. This solves the problems of low free radical utilization, insufficient non-free radical activity, and difficulty in synergistic interaction between free radicals and non-free radicals in existing technologies. This invention utilizes a spacer-based covalent organic framework to treat organic pollutant wastewater. Under the action of the spacer-based covalent organic framework, a highly efficient, selective, and stable pollutant degradation system can be constructed, thereby efficiently degrading organic pollutants in wastewater. It is particularly suitable for wastewater treatment and the degradation of persistent organic pollutants, and has advantages such as simple process, convenient operation, low cost, high degradation efficiency, good degradation effect, and good adaptability. It is a highly efficient and controllable photocatalytic treatment strategy for organic pollutants.

[0025] (2) The spacer-based covalent organic framework used in this invention possesses excellent environmental adaptability and reusability. It maintains high degradation efficiency of organic pollutants in various types of natural water bodies (such as river water, landfill leachate, and pharmaceutical wastewater). Simultaneously, this spacer-based covalent organic framework exhibits good tolerance to changes in environmental conditions, operating efficiently in water bodies with varying pH levels and ionic strengths without significant activity reduction due to system complexity. Furthermore, the spacer-based covalent organic framework maintains stable structure and catalytic performance after multiple cycles, demonstrating good repeatability and durability. These characteristics significantly enhance the applicability and promotional value of the spacer-based covalent organic framework in complex real-world environments, enabling it to meet the needs of water treatment in various scenarios. Attached Figure Description

[0026] 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.

[0027] Figure 1 The XRD diffraction patterns are those of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) prepared in Example 1 of this invention.

[0028] Figure 2 Fourier transform infrared spectra of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) prepared in Example 1 of this invention.

[0029] Figure 3The diagram shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) on acetaminophen in Example 1 of the present invention.

[0030] Figure 4 The graph shows the degradation effect of the olefin spacer covalent organic framework (Tapt-TD COF) on acetaminophen under different capture agent conditions in Example 2 of this invention.

[0031] Figure 5 The graph shows the degradation effect of alkyl spacer covalent organic framework (Tapt-BD COF) on acetaminophen under different capture agent conditions in Example 2 of this invention.

[0032] Figure 6 This is a graph showing the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen under different scavenging agent conditions in Example 2 of the present invention.

[0033] Figure 7 This is a graph showing the contribution ratio of free radicals and non-free radicals during the degradation of acetaminophen by benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) in Example 2 of the present invention.

[0034] Figure 8 The graph shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen under different pH conditions in Example 3 of this invention.

[0035] Figure 9 The graph shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen at different temperatures in Example 4 of this invention.

[0036] Figure 10 The graph shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen in different natural water bodies in Example 5 of this invention.

[0037] Figure 11 This diagram illustrates the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen in Example 6 of this invention.

[0038] Figure 12 The Fourier transform infrared spectra of the benzene ring spacer covalent organic framework (Tapt-BDD COF) before and after recycling in Example 6 of the present invention are shown. Detailed Implementation

[0039] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1 A method for treating organic pollutant wastewater using a spacer-based covalent organic framework specifically involves using the spacer-based covalent organic framework as a photocatalyst to degrade acetaminophen in the wastewater, including the following steps: 12 mg of each of the following covalent organic frameworks were weighed: benzene ring spacer group covalent organic framework (Tapt-BDD COF), olefin spacer group covalent organic framework (Tapt-TD COF), and alkyl spacer group covalent organic framework (Tapt-BD COF). Each was added to 60 mL of acetaminophen solution with a concentration of 5 mg / L (pH 6.1). The mixture was magnetically stirred at 500 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 10 min to carry out a photocatalytic reaction, thus completing the degradation of acetaminophen in the wastewater.

[0041] In this embodiment, the preparation method of the benzene ring spacer covalent organic framework (Tapt-BDD COF) specifically involves using 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxaldehyde as raw materials, and carrying out an imine condensation reaction under the conditions of organic solvent and catalyst, including the following steps: (1) Weigh 17.7 mg of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and 18.5 mg of benzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxaldehyde and mix them in a vacuum tube. Add 0.3 mL of o-dichlorobenzene and 0.7 mL of n-butanediol respectively, sonicate for 10 min to mix evenly, then add 0.1 mL of 6M acetic acid, sonicate for 3 min, mix evenly to obtain a mixture.

[0042] (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.

[0043] (3) The reaction product in step (2) was washed three times with tetrahydrofuran and methanol (10 mL each time), filtered with a 0.22 μm organic filter membrane, and then dried at 80 °C for 12 h under vacuum to obtain a benzene ring spacer covalent organic framework, denoted as Tapt-BDD COF.

[0044] In this embodiment, the preparation method of the olefin spacer covalent organic framework (Tapt-TD COF) specifically involves using 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and thieno[3,2-b]thiophene-2,5-dicarboxaldehyde as raw materials, and carrying out an imine condensation reaction under the conditions of organic solvent and catalyst, including the following steps: (1) Weigh 21.3 mg of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and 17.6 mg of thieno[3,2-b]thiophene-2,5-dicarboxaldehyde and mix them in a vacuum tube. Add 0.5 mL of o-dichlorobenzene and 1 mL of n-butanediol to each tube and sonicate for 10 min to mix them evenly. Then add 0.1 mL of acetic acid and sonicate for 3 min to mix them evenly to obtain a mixture.

[0045] (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.

[0046] (3) The reaction product in step (2) was washed three times with tetrahydrofuran and methanol (10 mL each time), filtered with a 0.22 μm organic filter membrane, and then dried at 80 °C for 12 h under vacuum to obtain an olefin spacer covalent organic framework, denoted as Tapt-TD COF.

[0047] In this embodiment, the preparation method of the alkyl spacer covalent organic framework (Tapt-BD COF) specifically involves using 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and [2,2']-bisthiophene-5,5'-dicarboxaldehyde as raw materials, and carrying out an imine condensation reaction under the conditions of organic solvent and catalyst, including the following steps: (1) Weigh 21.3 mg of 2,4,6-tris(4-aldehydephenyl)-1,3,5-triazine and 20.0 mg of [2,2']-bisthiophene-5,5'-dicarboxaldehyde and mix them in a vacuum tube. Add 0.3 mL of o-dichlorobenzene and 0.7 mL of n-butanediol respectively, sonicate for 10 min to mix evenly, and then add 0.1 mL of acetic acid and sonicate for 3 min to mix evenly to obtain a mixture.

[0048] (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.

[0049] (3) The reaction product in step (2) was washed three times with tetrahydrofuran and methanol (10 mL each time), filtered with a 0.22 μm organic filter membrane, and then dried at 80 °C for 12 h under vacuum to obtain an alkyl spacer covalent organic framework, denoted as Tapt-BD COF.

[0050] Figure 1 The images show the XRD diffraction patterns of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) prepared in Example 1 of this invention. Figure 1 It can be seen that all three spacer-based covalent organic frameworks contain the characteristic peak (100) of the covalent organic skeleton, which is consistent with the crystal structure of COFs, indicating that the main body of these three materials is a covalent organic skeleton. In addition, from Tapt-TD COF to Tapt-BD COF and then to Tapt-BDD COF, the diffraction angle of the (100) plane gradually increases, indicating that the pore size of COFs gradually increases. At the same time, compared with Tapt-TD COF and Tapt-BD COF, Tapt-BDD COF has significantly enhanced skeleton rigidity and π conjugation due to the introduction of benzene ring spacer groups, making its interlayer stacking more ordered and its crystal structure more stable. Moreover, the extended conjugated structure facilitates the transport and separation of electrons in the skeleton, enhancing the photoresponse performance. This makes Tapt-BDD COF have better photocatalytic performance, which is conducive to achieving efficient degradation of organic pollutants under visible light irradiation.

[0051] Figure 2 These are Fourier transform infrared (FTIR) spectra of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) prepared in Example 1 of this invention. Figure 2 As can be seen, the formation of imine bonds was detected in the Fourier transform infrared spectra of the three different spacer group covalent organic frameworks of the present invention, confirming the successful preparation of the three different spacer group covalent organic frameworks.

[0052] During magnetic stirring and photocatalysis, 1 mL samples were 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 concentration of organic matter after adsorption and after light irradiation. This allowed for the determination of the adsorption and photocatalytic degradation effects of three covalent organic frameworks with different spacer groups on acetaminophen. The results are as follows: Figure 3 As shown.

[0053] Figure 3 This image shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) on acetaminophen in Example 1 of this invention. Figure 3 It can be seen that after 1 hour of dark reaction adsorption and 5 minutes of light irradiation, the removal rates of acetaminophen by Tapt-TD COF, Tapt-BD COF, and Tapt-BDD COF were 83.1%, 64.9%, and 95.6%, respectively, and their degradation rates were 0.33 min. -1 0.19 min -1 0.80 min -1 It is evident that all three covalent organic framework photocatalysts with different spacer groups can effectively remove acetaminophen, with the benzene ring spacer group (Tapt-BDD COF) showing the most significant degradation effect, exhibiting a higher reaction rate and degradation efficiency. This indicates that the framework spacer group structure has a significant impact on photocatalytic activity.

[0054] Example 2 A method for treating organic pollutant wastewater using a spacer-based covalent organic framework specifically involves: determining the free radicals and non-free radicals present in the spacer-based covalent organic framework to participate in the degradation of acetaminophen by adding a scavenging agent, including the following steps: Two portions of each of the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) prepared in Example 1, each 12 mg, were added to a solution of acetaminophen containing furfuryl alcohol and p-benzoquinone as capture agents (the solution volume was 60 mL, the concentration was 5 mg / L, and the pH was 6.1). The mixture was magnetically stirred at 500 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 10 min to carry out a photocatalytic reaction, thus completing the degradation of acetaminophen in the wastewater.

[0055] During the magnetic stirring and photocatalysis process, 1 mL samples were taken at 1, 3, 5, 7, and 10 min. The samples were filtered using a 0.22 μm filter head, and the filtrate was measured by liquid chromatography to determine the concentration of organic matter after adsorption and after light irradiation. This allowed us to obtain the photocatalytic degradation effect of three different spacer groups on the covalent organic framework and determine the contribution of free radicals and non-free radicals.

[0056] Figure 4 This image shows the degradation effect of the olefin spacer covalent organic framework (Tapt-TD COF) on acetaminophen under different trapping agent conditions in Example 2 of this invention. Figure 4 It was found that the addition of a superoxide radical scavenger significantly inhibited the degradation of acetaminophen by Tapt-TD COF, while the addition of a singlet oxygen scavenger only showed a slight inhibitory effect. This indicates that in the Tapt-TD COF catalytic system, superoxide radicals are the dominant active species, while singlet oxygen also participates in the reaction process, but its role is relatively minor. The ratio of free radicals to non-free radicals in the olefin spacer covalent organic framework (Tapt-TD COF) system is 9.9:1. Therefore, the olefin spacer structure mainly achieves efficient degradation of organic pollutants by promoting the generation of superoxide radicals.

[0057] Figure 5 This image shows the degradation effect of the alkyl spacer covalent organic framework (Tapt-BD COF) on acetaminophen under different scavenging agent conditions in Example 2 of this invention. Figure 5 It was found that the degradation of acetaminophen was significantly inhibited after the addition of a superoxide radical scavenger; simultaneously, the degradation rate was also significantly slowed down after the addition of a singlet oxygen scavenger. The ratio of free radicals to non-free radicals in the alkyl spacer covalent organic framework (Tapt-BD COF) system was 2.4:1. This indicates that both superoxide radicals and singlet oxygen play a role in the reaction process in the Tapt-BD COF catalytic system, but the overall degradation efficiency of Tapt-BDCOF is low, possibly due to a lack of effective utilization of active species.

[0058] Figure 6 This image shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen under different trapping agent conditions in Example 2 of this invention. Figure 6 It can be seen that the degradation efficiency of acetaminophen decreased significantly after the addition of a superoxide radical scavenger; and the degradation rate was also significantly inhibited after the addition of a singlet oxygen scavenger. The ratio of free radicals to non-free radicals in the benzene ring spacer covalent organic framework (Tapt-BDD COF) system was 2.0:1. This indicates that both superoxide radicals and singlet oxygen play key roles in the degradation process in the Tapt-BDD COF catalytic system.

[0059] Figure 7 This diagram illustrates the contribution ratios of free radicals and non-free radicals during the degradation of acetaminophen by the benzene ring spacer covalent organic framework (Tapt-BDD COF), olefin spacer covalent organic framework (Tapt-TD COF), and alkyl spacer covalent organic framework (Tapt-BD COF) in Example 2 of this invention. Figure 7 It is evident that the olefin-spacer covalent organic framework (Tapt-TDCOF) primarily relies on superoxide radicals for its function, with limited contributions from non-radicals; the alkyl-spacer covalent organic framework (Tapt-BD COF) involves both free radicals and non-radicals, exhibiting a certain synergistic effect; while the benzene-ring-spacer covalent organic framework (Tapt-BDD COF) achieves a more balanced contribution from both free radicals and non-radicals, further enhancing the role of singlet oxygen, thus resulting in a more significant synergistic degradation effect. This indicates that by rationally designing the skeletal spacer structure, the ratio of free radicals to non-radicals can be effectively controlled (within the range of 9.8-2.0), achieving synergistic regulation of both and ultimately improving photocatalytic degradation efficiency.

[0060] The results above show that experimental analysis of different spacer-based covalent organic frameworks (COFs) in the degradation of acetaminophen reveals that different spacer structures significantly affect the generation and relative proportions of active species in the photocatalyst. The olefin-spacer-based COF primarily relies on superoxide radicals for degradation, while the alkyl-spacer-based COF exhibits partial synergy between free radicals and non-free radicals. The benzene-ring-based COF achieves a more balanced contribution from both free radicals and non-free radicals, enhancing the role of singlet oxygen and ultimately exhibiting the best overall degradation effect. This indicates that the rational design of the spacer structure can regulate the generation mode of active species in the photocatalytic system, allowing free radicals and non-free radicals to complement each other in the degradation reaction, thereby optimizing the reaction pathway and improving the comprehensive degradation performance of photocatalysts for organic pollutants. This provides a practical basis for developing efficient, stable, and controllable methods for water pollution treatment.

[0061] Example 3 A method for treating organic pollutant wastewater using a spacer-based covalent organic framework specifically involves using a benzene ring spacer-based covalent organic framework as a photocatalyst to degrade acetaminophen in wastewater at different pH levels, including the following steps: Five portions of the benzene ring spacer covalent organic framework (Tapt-BDD COF) prepared in Example 1, each 12 mg, were weighed and added to acetaminophen solutions with pH values ​​of 3, 5, 7, 9, and 11 (the solution volume was 60 mL and the concentration was 5 mg / L). The solutions were magnetically stirred at 500 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 10 min to carry out a photocatalytic reaction, thus completing the degradation of acetaminophen in the wastewater.

[0062] During the magnetic stirring and photocatalysis process, 1 mL samples were taken at 1, 3, 5, 7, and 10 min. The samples were filtered using a 0.22 μm filter, and the filtrate was measured by liquid chromatography to determine the concentration of organic matter after adsorption and after light irradiation, thereby obtaining the adsorption effect and photocatalytic degradation effect of Tapt-BDD COF on acetaminophen.

[0063] Figure 8 This image shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen under different pH conditions in Example 3 of this invention. Figure 8 It is known that the benzene ring spacer covalent organic framework (Tapt-BDD COF) of the present invention achieved removal rates of 99.5%, 96.4%, 96.1%, 96.6%, and 99.2% for acetaminophen at pH values ​​of 3, 5, 7, 9, and 11, respectively. Generally, pH value affects the ionization degree of organic matter; under acidic or alkaline conditions, it may become charged, thereby altering its adsorption behavior and reactivity on the catalyst surface. However, the benzene ring spacer covalent organic framework (Tapt-BDD COF) prepared in this invention exhibits excellent degradation performance at pH values ​​from 3 to 11, indicating that the benzene ring spacer covalent organic framework (Tapt-BDD COF) of the present invention possesses strong stability and excellent adaptability.

[0064] Example 4: A method for treating organic pollutant wastewater using a spacer-based covalent organic framework specifically involves using a benzene ring spacer-based covalent organic framework as a photocatalyst to degrade acetaminophen under different temperature conditions, including the following steps: Four portions of the benzene ring spacer covalent organic framework (Tapt-BDD COF) prepared in Example 1 were weighed, each 12 mg, and added to acetaminophen solutions at temperatures of 5℃, 10℃, 25℃, and 45℃ (the solution volume was 60 mL and the concentration was 5 mg / L). The solutions were magnetically stirred at 500 r / min for 1 h in the dark to reach adsorption equilibrium. Then, the light source was turned on, and the solutions were irradiated under simulated sunlight (visible light with λ≥420 nm) for 10 min to carry out photocatalytic reaction, thus completing the degradation of acetaminophen in the wastewater.

[0065] Adsorption equilibrium refers to the state when the concentration of the adsorbate in the solution and the concentration on the surface of the adsorbent no longer change.

[0066] During the magnetic stirring and photocatalysis process, 1 mL samples were taken at 1, 3, 5, 7, and 10 min. The samples were filtered using a 0.22 μm filter, and the filtrate was measured by liquid chromatography to determine the concentration of organic matter after adsorption and after light irradiation, thereby obtaining the photocatalytic degradation effect of Tapt-BDD COF on acetaminophen.

[0067] Figure 9 This image shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen at different temperatures in Example 4 of this invention. Figure 9 It was found that when the reaction temperatures were 5℃, 10℃, 25℃, and 45℃, the removal rates of acetaminophen by the benzene ring spacer covalent organic framework (Tapt-BDD COF) were 95.8%, 95.8%, 95.4%, and 94.9%, respectively. These results confirm that the removal rate of acetaminophen by the benzene ring spacer covalent organic framework (Tapt-BDD COF) does not change significantly at different reaction temperatures, and also indicate that the benzene ring spacer covalent organic framework (Tapt-BDD COF) exhibits relatively stable activity within the temperature range of 5~45℃.

[0068] Example 5: A method for treating organic pollutant wastewater using a spacer-based covalent organic framework specifically involves using a benzene ring spacer-based covalent organic framework as a photocatalyst to degrade acetaminophen in different water bodies, including the following steps: Four portions of the benzene ring spacer covalent organic framework (Tapt-BDD COF) prepared in Example 1, each 12 mg, were weighed and added to acetaminophen solutions prepared from ultrapure water, lake water, landfill leachate, and pharmaceutical wastewater (the solution volume was 60 mL, concentration was 5 mg / L, and pH was 6.1). The solutions were magnetically stirred at 500 r / min for 1 h in the dark to reach adsorption equilibrium. Then, the light source was turned on, and the solutions were irradiated under simulated sunlight (visible light with λ≥420 nm) for 10 min to carry out photocatalytic reaction, thus completing the degradation of acetaminophen in the wastewater.

[0069] During the magnetic stirring and photocatalysis process, 1 mL samples were taken at 1, 3, 5, 7, and 10 min. The samples were filtered using a 0.22 μm filter, and the filtrate was measured by liquid chromatography to determine the concentration of organic matter after adsorption and after light irradiation, thereby obtaining the photocatalytic degradation effect of Tapt-BDD COF on acetaminophen.

[0070] Figure 10 This image shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen in different natural water bodies in Example 5 of this invention. From... Figure 10 It is evident that Tapt-BDD COF can achieve efficient degradation in natural water bodies (such as lakes), indicating that naturally occurring dissolved organic matter, ions, and impurities in the water have limited interference with its photocatalytic performance. In complex industrial water bodies (such as landfill leachate and pharmaceutical wastewater), Tapt-BDD COF still maintains excellent catalytic activity. In landfill leachate, the degradation efficiency is close to ideal conditions, and although the degradation rate is slightly reduced in pharmaceutical wastewater, it still achieves efficient removal of the target pollutants. These results demonstrate that the benzene ring spacer covalent organic framework can not only stably generate reactive oxygen species (including superoxide radicals and singlet oxygen) under different water quality conditions, maintaining the synergistic effect of free radicals and non-free radicals, but also possesses significant anti-interference ability and environmental adaptability, showing its broad application potential in the treatment of complex water pollution.

[0071] Example 6: A method for treating organic pollutant wastewater using a spacer-based covalent organic framework specifically involves using a benzene ring spacer-based covalent organic framework as a photocatalyst to degrade acetaminophen in different water bodies, including the following steps: Weigh 12 mg of the benzene ring spacer covalent organic framework (Tapt-BDD COF) prepared in Example 1 and add it to 60 mL of acetaminophen solution with a concentration of 5 mg / L and a pH of 6.1. Under dark conditions, the mixture is magnetically stirred at 500 r / min for 1 h to reach adsorption equilibrium. Then, the light source is turned on and the mixture is irradiated under simulated sunlight (visible light with λ≥420 nm) for 10 min to carry out a photocatalytic reaction, thereby completing the degradation of acetaminophen in the wastewater.

[0072] After degradation, the washed benzene ring spacer covalent organic framework was recovered and dried by heating at 80°C for 12 hours. The photocatalyst was then used to treat acetaminophen solutions.

[0073] Repeat the above steps four times to obtain the photocatalytic degradation effect of Tapt-BDD COF on acetaminophen.

[0074] Figure 11 This image shows the degradation effect of the benzene ring spacer covalent organic framework (Tapt-BDD COF) on acetaminophen in Example 6 of this invention. From... Figure 11 It can be seen that Tapt-BDD COF can still maintain a paracetamol removal efficiency of over 95% after five consecutive cycles, indicating that the photocatalyst has excellent cycle stability and reusability. This result shows that the benzene ring spacer covalent organic framework can maintain structural integrity and active species generation ability during long-term use, demonstrating good durability and practical application value.

[0075] Figure 12 These are Fourier transform infrared spectra of the benzene ring spacer covalent organic framework (Tapt-BDD COF) before and after recycling in Example 6 of this invention. Figure 12 It can be seen that after five cycles of use, the characteristic peak of the imine bond in the benzene ring spacer covalent organic framework is still clearly present, indicating that its framework structure remains intact and has not undergone significant degradation or damage. This further demonstrates that Tapt-BDD COF has excellent structural stability during repeated photocatalysis, providing a reliable guarantee for its long-term cyclic use.

[0076] The results above show that, compared with traditional covalent organic framework photocatalysts, the spacer-based covalent organic framework used in this invention has the following advantages: (a) It has a highly ordered porous structure, maintaining a large specific surface area and suitable pore size distribution, enhancing the transport efficiency of reactants and products within the spacer-based covalent organic framework, which is beneficial for improving the photocatalytic degradation rate; (b) By introducing different types of spacer groups (such as olefins, alkyl groups, and benzene rings) into the framework, the electronic structure and reactive site distribution can be effectively adjusted, not only achieving the desired effect on O2...- and 1 O2 generation is controlled (by regulating the ratio of free radicals to non-free radicals between 9.9 and 2.0), and the generation of O2 has been achieved. - and 1 The synergistic effect of O2 enables the construction of a highly efficient, selective, and stable pollutant degradation system, significantly improving the degradation efficiency and effect on organic pollutants. This solves the problems of low free radical utilization, insufficient non-free radical activity, and difficulty in synergistic interaction between free radicals and non-free radicals in existing technologies. Therefore, this invention utilizes a spacer-based covalent organic framework to treat organic pollutant wastewater. Under the action of the spacer-based covalent organic framework, a highly efficient, selective, and stable pollutant degradation system can be constructed, thereby efficiently degrading organic pollutants in wastewater. It is particularly suitable for wastewater treatment and the degradation of persistent organic pollutants, and has the advantages of simple process, convenient operation, low cost, high degradation efficiency, good degradation effect, and good adaptability. It is a highly efficient and controllable photocatalytic treatment strategy for organic pollutants.

[0077] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating organic contaminant wastewater using a spacer-based covalent organic framework, characterized in that, The method is to degrade and treat organic pollutants in wastewater by taking a light catalyst of a spacer covalent organic framework; the spacer covalent organic framework is at least one of an olefin spacer covalent organic framework, an alkyl spacer covalent organic framework, and a benzene ring spacer covalent organic framework.

2. The method of claim 1, wherein, The preparation method of the olefin spacer covalent organic framework is to take 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and thieno[3,2-b]thiophene-2,5-dicarboxaldehyde as raw materials, and to react under the condition of an organic solvent and a catalyst to obtain the olefin spacer covalent organic framework; The preparation method of the alkyl spacer covalent organic framework is to take 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and [2,2']-bithiophene-5,5'-dicarboxaldehyde as raw materials, and to react under the condition of an organic solvent and a catalyst to obtain the alkyl spacer covalent organic framework; The preparation method of the benzene ring spacer covalent organic framework is to take 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and benzene[1,2-b:4,5-b']dithiophene-2,6-dicarboxaldehyde as raw materials, and to react under the condition of an organic solvent and a catalyst to obtain the benzene ring spacer covalent organic framework.

3. The method of claim 2, wherein, The mass ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and the thieno[3,2-b]thiophene-2,5-dicarboxaldehyde is 21.3:17.6; The mass ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and the [2,2']-bithiophene-5,5'-dicarboxaldehyde is 21.3:20; The mass ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and the benzene[1,2-b:4,5-b']dithiophene-2,6-dicarboxaldehyde is 17.7:18.

5.

4. The method of claim 3, wherein, In the preparation method of the olefin spacer covalent organic framework, the mass-volume ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and the organic solvent is 21.3 mg:1.5 mL, the organic solvent is a mixed solution of o-dichlorobenzene and n-butandiol, the volume of the o-dichlorobenzene and the n-butandiol is 1:2, the mass-volume ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and the catalyst is 21.3 mg:0.1 mL, the catalyst is acetic acid, the concentration of the acetic acid is 6M, the temperature of the reaction is 120 DEG C, and the time of the reaction is 72 h. In the preparation method of the alkyl-spaced covalent organic framework, the mass-volume ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to the organic solvent is 21.3 mg: 1 mL, the organic solvent is a mixed solution of o-dichlorobenzene and n-butanediol, the volume of the o-dichlorobenzene and the n-butanediol is 3:7, the mass-volume ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to the catalyst is 21.3 mg: 0.1 mL, the catalyst is acetic acid, the concentration of the acetic acid is 6M, the temperature of the reaction is 120 DEG C, and the time of the reaction is 72h. In the preparation method of the benzene ring-spaced covalent organic framework, the mass-volume ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to the organic solvent is 17.7 mg: 1 mL, the organic solvent is a mixed solution of o-dichlorobenzene and n-butanediol, the volume of the o-dichlorobenzene and the n-butanediol is 3:7, the mass-volume ratio of the 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to the catalyst is 21.3 mg: 0.1 mL, the catalyst is acetic acid, the concentration of the acetic acid is 6M, the temperature of the reaction is 120 DEG C, and the time of the reaction is 72h.

5. The method according to any one of claims 1 to 4, characterized in that, The method for degrading and treating organic pollutants in wastewater by using the spaced covalent organic framework as a photocatalyst comprises the following steps: mixing the spaced covalent organic framework with the organic pollutant wastewater, and performing a photocatalytic reaction under light to complete the degradation of the organic pollutants in the wastewater.

6. The method of claim 5, wherein, The ratio of the spaced covalent organic framework to the organic pollutant wastewater is 0.05g-0.3g: 1L.

7. The method of claim 6, wherein, The initial concentration of the organic pollutants in the organic pollutant wastewater is ≤5mg / L; and the organic pollutants are at least one of acetaminophen, 2,4-dichlorophenol, p-chlorophenol, p-hydroxyanisole, and tetracycline.

8. The method of claim 7, wherein, The initial pH value of the organic pollutant wastewater is 5-9.

9. The method of claim 6, wherein, The mixing is performed in the dark; the stirring speed during the mixing is controlled to be 400r / min-500r / min, and the stirring time is 1h.

10. The method of claim 9, wherein, The time of the photocatalytic reaction is ≥10min.

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