Triazine ring-containing polyimide covalent organic framework material, preparation method and environmental application

Abstract

The invention belongs to the technical field of photo-assisted Fenton, and particularly relates to a triazine ring-containing polyimide covalent organic framework material, a preparation method and application thereof, and the material has good application in the aspect of activating potassium monopersulfate (PMS) to degrade organic pollutants. The preparation method of the triazine ring-containing polyimide covalent organic framework material comprises the following steps: taking 1, 4, 5, 8-naphthalene tetracarboxylic anhydride and melamine as synthesis precursors, and carrying out Schiff base reaction to obtain the triazine ring-containing polyimide covalent organic framework material. The polyimide covalent organic framework prepared by the preparation method disclosed by the invention has relatively strong anti-interference capability, relatively high singlet oxygen selectivity, relatively high catalytic degradation activity and cycling stability, and relatively high application prospect in the field of catalytic degradation of organic pollutants such as antibiotics.

Description

Technical Field

[0001] The invention relates to a preparation method of a triazine ring-containing polyimide covalent organic framework material and application of the material in assisting Fenton-like degradation of antibiotics, belonging to the technical field of photocatalysis and Fenton-like technologies. Background Art

[0002] In the context of increasingly severe environmental problems today, the residue of antibiotics in water bodies has become a major challenge. Traditional water treatment methods have certain limitations in removing antibiotics. The Fenton-like system based on monopersulfate (PMS) is considered to have great potential in solving the problem of antibiotic pollution. At present, the main methods for activating PMS include ultraviolet activation, thermal activation, transition metal activation, etc. However, thermal activation and ultraviolet activation require a lot of energy, and transition metal activation has the problem of metal ion leaching and secondary pollution. Finding a green and efficient solution for activating PMS is still a topic worth studying.

[0003] Photocatalysis is considered a green method for activating PMS because it can use sunlight and consumes less energy. The catalyst can generate photogenerated carriers under the excitation of visible light, which activate PMS and promote the formation of reactive oxygen species. A large number of studies have shown that the triazine ring has abundant nitrogen sites, and the lone pair of electrons enables it to act as a good electron donor. After being excited by light, the nitrogen atoms can interact with the photogenerated holes to promote the separation of carriers, thereby improving the efficiency of the photocatalytic reaction.

[0004] Covalent organic frameworks (COFs) have shown great potential in the field of photocatalysis due to their unique structure and properties. COFs have a highly ordered porous structure, which enables them to provide a large number of active sites, which is conducive to the separation and transport of photogenerated carriers. At the same time, COFs can regulate their optical and electronic properties through precise molecular design, thereby achieving efficient catalysis of specific reactions.

[0005] Singlet oxygen is a typical non-radical active substance. Due to its strong oxidation ability and long life, the catalyst shows high activity and stability in the photo-assisted Fenton degradation of antibiotics. So far, there is no precedent for introducing triazine rings to construct donor-acceptor COFs and using photogenerated holes to in situ oxidize PMS to produce singlet oxygen with high selectivity. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention aims to provide a triazine ring-containing polyimide covalent organic framework material, a preparation method and an application thereof. The present invention prepares a polyimide covalent organic framework with a donor-acceptor relationship for the first time. The introduction of the triazine ring generates photogenerated holes after being excited by visible light, in situ oxidizes PMS, promotes the highly selective generation of singlet oxygen, has strong anti-interference ability, and exhibits high catalytic activity and cyclic stability in the photo-assisted Fenton degradation of antibiotics.

[0007] The specific preparation process of the triazine ring-containing polyimide covalent organic framework material (PI-COF) includes the following steps: A certain amount of 1,4,5,8-naphthalenetetracarboxylic anhydride and melamine are added to N,N-dimethylformamide and ethylene glycol for ultrasonic dissolution, and then nitrogen bubbling is performed to expel the air to obtain a mixture, which is then transferred into a polytetrafluoroethylene high-pressure reactor for a closed hydrothermal reaction, and then filtered, washed and dried to obtain a polyimide covalent organic framework material (PI-COF) containing a triazine ring.

[0008] Furthermore, the molar ratio of 1,4,5,8-naphthalenetetracarboxylic anhydride to melamine is 1.36:1.

[0009] Furthermore, the volume ratio of N,N-dimethylformamide to ethylene glycol is 1:1.

[0010] Furthermore, the ultrasonic dissolution time was 15 min and the nitrogen bubbling time was 15 min.

[0011] Furthermore, the hydrothermal temperature was 180 °C and the hydrothermal time was 70 h.

[0012] Furthermore, the material is a nanorod-like structure, carbon, nitrogen and oxygen elements are evenly distributed on the material, and the material is prepared according to the preparation method.

[0013] The present invention claims to protect the use of the above-mentioned triazine ring-containing polyimide covalent organic framework (PI-COF) in the degradation of antibiotics.

[0014] Further, the antibiotics include levofloxacin.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention prepares a triazine ring-containing polyimide covalent organic framework based on a hydrothermal method. The polyimide covalent organic framework has strong anti-interference ability and high singlet oxygen selectivity in the advanced oxidation catalytic degradation of organic pollutants. It also has high catalytic degradation activity and cyclic stability. The absence of metal materials will not cause secondary pollution, and the framework has high application prospects in the field of antibiotic degradation. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1The XRD diagrams of the products of Example 1 and Comparative Example 1 are shown; Figure 2 FTIR images of the products of Example 1 and Comparative Example 1; Figure 3 The SEM images of the products of Example 1 and Comparative Example 1 are shown; Figure 4 HREM image and mapping image of the product of Example 1; Figure 5 The photo-assisted Fenton degradation activity diagram of the products of Example 1 and Comparative Example 1; Figure 6 is the EPR of the product of Example 1; Figure 7 This is the activity diagram of the product of Example 1 in photo-assisted Fenton degradation of LVX under the influence of 5 mM different ions and 5 mg / L humic acid; Figure 8 This is a cycle test diagram of the photo-assisted Fenton degradation of LVX by the product of Example 1. Fig. 9 This is the activity diagram of the product of Example 1 in degrading LVX under different water environments.

Claims

1. A method for preparing a triazine ring-containing polyimide covalent organic framework material, characterized in that The specific preparation steps are as follows: The first step: adding a certain amount of 1,4,5,8-naphthalenetetracarboxylic anhydride and melamine into N,N-dimethylformamide and ethylene glycol for ultrasonic dissolution, and then bubbling with nitrogen to expel air to obtain a mixture; Step 2: The mixture is transferred into a polytetrafluoroethylene high-pressure reactor for a closed hydrothermal reaction, and filtered, washed and dried to obtain a polyimide covalent organic framework material containing a triazine ring, which is denoted as PI-COF.

2. The preparation method according to claim 1, characterized in that: In the first step, the molar ratio of 1,4,5,8-naphthalenetetracarboxylic anhydride to melamine is 1.37:

1.

3. The preparation method according to claim 1, characterized in that: In the first step, the volume ratio of N,N-dimethylformamide to ethylene glycol is 1:

1.

4. The preparation method according to claim 1, characterized in that: In the first step, the ultrasonic dissolution time was 15 min and the nitrogen bubbling time was 15 min.

5. The preparation method according to claim 1, characterized in that: In the second step, the hydrothermal temperature was 180 °C and the hydrothermal time was 70 h.

6. The preparation method according to claim 1, characterized in that: In the third step, the filtering method is centrifugation, and after filtering, ethanol is used for centrifugal washing and drying to obtain a polyimide covalent organic framework material containing a triazine ring.

7. Use of the triazine ring-containing polyimide covalent organic framework according to claim 7 in antibiotic degradation.

8. The use according to claim 8, characterized in that: The antibiotics include levofloxacin.

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