Preparation method and application of pyridine nitrogen-containing pyrene-based covalent organic framework material

Abstract

The application discloses a preparation method and application of pyridine nitrogen-containing pyrene-based covalent organic framework material, and the material has good application in activating potassium monopersulfate (PMS) to degrade organic pollutants. The preparation method of the pyridine nitrogen-containing pyrene-based covalent organic framework material comprises the following steps: taking 1, 3, 6, 8-tetra-(p-aminophenyl)-pyrene and 2, 6-pyridine dicarboxaldehyde as synthetic precursors, and obtaining the pyridine nitrogen-containing pyrene-based covalent organic framework material through Schiff base reaction. By introducing the pyridine nitrogen structure, the application remarkably improves the ability of PMS activation, shows high efficient catalytic degradation capacity for bisphenol A, and has important application value and application prospect in degrading organic pollutants, and the material is stable and cannot cause secondary pollution, and can be recycled.

Description

Technical Field

[0001] This invention relates to a method for preparing a pyrene-based covalent organic framework material containing pyridine nitrogen and its application in the degradation of organic pollutants by activated PMS, belonging to the fields of materials and advanced oxidation technology. Background Technology

[0002] With the acceleration of industrialization, the emission of organic pollutants into the environment is increasing, posing a serious threat to the ecological environment and human health. Therefore, finding efficient and green methods for treating organic pollutants has become an important research topic in the environmental field.

[0003] Traditional methods for treating organic pollutants, such as physical adsorption and biodegradation, have certain limitations. Physical adsorption merely transfers pollutants from one phase to another, failing to completely degrade them; biodegradation is limited by environmental conditions and microbial adaptability, resulting in low treatment efficiency. Advanced oxidation technologies based on PMS, however, can effectively remove organic pollutants due to their strong oxidizing properties. Transition metals are widely used to activate PMS, but secondary pollution from metal ion leaching exists. Metal-free carbon materials can activate PMS to remove pollutants, but the activation effect is unsatisfactory and inefficient.

[0004] Covalent organic frameworks (COFs) are a novel class of porous crystalline materials. They possess a highly ordered structure, tunable pore size, and a functionalized framework, providing abundant active sites. They show great potential in activating persulfate degradation of organic pollutants. Using COFs to activate persulfate degradation of pollutants can fully utilize their large specific surface area, exposing more active sites for PMS activation. COF materials are easy to synthesize and do not generate secondary pollution, making them green and environmentally friendly catalysts. They hold promise as ideal materials for activating PMS to remove antibiotics, possessing significant theoretical and practical value in environmental remediation. Summary of the Invention

[0005] This invention discloses a method for preparing and applying a pyridine nitrogen-containing pyrene-based covalent organic framework, which exhibits good application in activating potassium persulfate (PMS) for the degradation of organic pollutants. The preparation method of this pyridine nitrogen-containing pyrene-based covalent organic framework material includes: using 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde as precursors, the pyridine nitrogen-containing pyrene-based covalent organic framework material is obtained through a Schiff base reaction. The material is synthesized via a hydrothermal method, resulting in a nanorod-like structure. The introduction of pyridine nitrogen increases the active sites of the material, significantly improving its ability to activate PMS. This material can effectively activate PMS to generate active species for the degradation of organic pollutants, exhibiting highly efficient catalytic degradation of bisphenol A. Furthermore, the material is stable, does not generate secondary pollution, and is recyclable, demonstrating significant application value and promising prospects in the degradation of organic pollutants.

[0006] Specifically, the preparation process of the pyridine nitrogen-containing pyrene-based covalent organic framework material (Tpy-PCBACOF) includes the following steps:

[0007] Step 1: Add a certain amount of 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde to 1,4-dioxane and 1,3,5-trimethylbenzene to dissolve them, then add a certain amount of acid catalyst, and bubble nitrogen gas through to remove air to obtain a mixture;

[0008] Step 2: The above mixture is transferred into a reactor for a closed hydrothermal reaction to obtain a pyrene-based covalent organic framework material with a nanorod structure containing pyridine nitrogen.

[0009] Furthermore, in the first step, the molar ratio of 1,3,6,8-tetra-(p-aminophenyl)-pyrene to 2,6-pyridinedicarboxaldehyde is 1:1.8-2.

[0010] Furthermore, in the first step, the acid catalyst is 0.5-1 mL of 6M acetic acid.

[0011] Furthermore, in the first step, the volume ratio of 1,4-dioxane to 1,3,5-trimethylbenzene is 1:0.9-1.

[0012] Furthermore, in the first step, the dissolution is performed by ultrasonic dissolution for 15-20 minutes; air is expelled by bubbling with nitrogen for 15-20 minutes.

[0013] Furthermore, in the second step, the hydrothermal temperature is 119-121℃ and the hydrothermal time is 72-72.5h.

[0014] A pyrene-containing covalent organic framework containing pyridine nitrogen, wherein the organic framework is prepared by the aforementioned preparation method.

[0015] The application of the pyridine nitrogen-containing pyrene covalent organic framework in the degradation of organic pollutants, wherein the organic pollutant is bisphenol A, and the application of the pyridine nitrogen-containing pyrene covalent organic framework in the presence of inorganic anions (0-5 mM) and humic acid (0-5 mg / L) in water.

[0016] The purpose of this invention is to provide the application of the Tpy-PCBA COF material as an advanced oxidation catalyst for catalytic activation of PMS, thereby improving the pollutant removal efficiency in water pollution treatment.

[0017] Beneficial technical effects:

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1) This invention is the first to prepare a pyrene-based covalent organic framework containing pyridine nitrogen. It has strong anti-interference ability and strong oxidation ability in the advanced oxidation catalytic degradation of organic pollutants. It also has high catalytic degradation activity and cycle stability. Since it is metal-free, it will not cause secondary pollution. It has high application prospects in the field of pollutant degradation.

[0020] 2) The material has a nanorod structure with carbon and nitrogen elements evenly distributed on the material, and has abundant active sites that are uniformly dispersed on the surface of the material.

[0021] 3) It has a large specific surface area and abundant active sites, which increases the contact between active sites and PMS, making PMS easier to be oxidized. Attached Figure Description

[0022] Figure 1 The image shows the XRD pattern of the product from Example 1.

[0023] Figure 2 The above is an FTIR spectrum of the product of Example 1 compared to the synthetic precursor;

[0024] Figure 3 TEM images of the products of Example 1 and Comparative Example 1;

[0025] Figure 4 This is a mapping diagram of the product of Example 1;

[0026] Figure 5 The N2 adsorption isotherm and pore size distribution of the pyridine nitrogen-containing pyrene-based covalent organic framework material obtained in Example 1 at 77 K are shown.

[0027] Figure 6 The images show the Fenton-like activity of the products from Example 1 and Comparative Example 1 in degrading bisphenol A.

[0028] Figure 7The activity diagram of Fenton-like degradation of bisphenol A by the product of Example 1 under the influence of different concentrations of inorganic anions (0-5mM) and different concentrations (0-5mg / L) of humic acid is shown.

[0029] Figure 8 This is a cyclic test diagram of the Fenton-like degradation of bisphenol A by the product of Example 1.

[0030] Figure 9 The diagram shows the activity of the product of Example 1 in degrading bisphenol A under different water conditions. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments. However, the scope of protection of the present invention is not limited to the following embodiments. Any non-essential adjustments and modifications made to the present invention based on the above description shall still fall within the scope of protection of the present invention.

[0032] Example 1

[0033] 0.15 mmol of 1,3,6,8-tetra-(p-aminophenyl)pyrene and 0.3 mmol of 2,6-pyridinedicarboxaldehyde were dissolved in 1.5 mL of 1,4-dioxane and 1.5 mL of 1,3,5-trimethylbenzene, and sonicated for 15 min. Then, 0.5 mL of 6M acetic acid was added, and the mixture was bubbled with nitrogen for 15 min. The mixture was then transferred to a polytetrafluoroethylene high-pressure reactor liner and heated at 120 °C for 72 h. After cooling to room temperature, the mixture was centrifuged and filtered, washed multiple times with water and ethanol, and dried at 70 °C for 12 h to obtain the Tpy-PCBACOF material.

[0034] Comparative Example 1

[0035] 0.15 mmol of 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 0.3 mmol of [2,2'-bipyridine]-6,6'-dicarboxaldehyde were dissolved in 1.5 mL of 1,4-dioxane and 1.5 mL of 1,3,5-trimethylbenzene, and sonicated for 15 min. Then, 0.5 mL of 6M acetic acid was added, and the mixture was bubbled with nitrogen for 15 min. The mixture was then transferred to a polytetrafluoroethylene high-pressure reactor liner and heated at 120 °C for 72 h. After cooling to room temperature, the mixture was centrifuged and filtered, washed multiple times with water and ethanol, and dried at 70 °C for 12 h to obtain the Typy-BD COF material.

[0036] The XRD pattern of the product obtained in Example 1 is shown below. Figure 1 As shown, by Figure 1 It can be seen that the appearance of the (100) crystal plane indicates that the product was successfully synthesized, the (001) crystal plane indicates that there is π-π stacking in COF, and the strong diffraction peaks indicate that COF is a crystalline material.

[0037] The FTIR spectra of the product and the precursor prepared in Example 1 are as follows: Figure 2 As shown, by Figure 2 It can be seen that after the reaction, the Ph-NH2 (3020cm) in TPy -1 ) and NH (3342cm -1 ) and C=O(1720cm) in PCBA -1 The characteristic adsorption peaks of the FT-IR spectra of precursors such as ) drop sharply, while C=N bonds appear in COF (1627 cm⁻¹). -1 The peak indicates that an imine bond was successfully formed via the Schiff base reaction, and Tpy-PCBA COF was synthesized.

[0038] TEM images of the products of Example 1 and Comparative Example 1 are shown below. Figure 3 As shown, the mapping diagram of Example 1 is as follows: Figure 4 As shown, by Figure 3 and Figure 4 It can be seen that Tpy-PCBACOF has a nanorod-like structure with C and N elements uniformly distributed on the COF surface, while Tpy-BD COF has a spherical structure. Tpy-PCBA COF is more likely to contact PMS. It is evident that the product structure changes significantly after changing the raw materials, demonstrating that the specific raw materials used in this invention have a very important influence on the product structure.

[0039] Figure 5 The attached diagram shows the nitrogen adsorption-desorption process and pore size distribution of the product from Example 1. Figure 5 It is known that the pore size of the Tpy-PCBA COF is 10.312 nm. Analysis and calculation show that its surface area is 403.005 m². 2 ·g -1 It is evident that the Tpy-PCBA COF has a large specific surface area, which is beneficial for increasing the contact area between COF and pollutants, and increasing the reaction sites and active sites for activating PMS.

[0040] Performance testing

[0041] The method for evaluating the degradation performance of simulated pollutants provided by this invention is as follows:

[0042] Weigh 10 mg each of the products obtained in Example 1 and Comparative Example 1, and add them to a 10 mg / L bisphenol A (BPA) solution. Stir the suspension with a magnetic stirrer. After reaching adsorption equilibrium, add 5 mM PMS. To obtain degradation kinetic data, take 1 mL of the solution at a specified time, filter it using a syringe with a 0.45 μm filter, and immediately add an equal volume of Na₂S₂O₃ to terminate the reaction. Then, analyze the concentration of the remaining BPA using high-performance liquid chromatography (HPLC, Shimadzu 2030C). After the reaction is complete, centrifuge and wash the catalyst, and then perform a cycle stability test.

[0043] Figure 6 The excellent catalytic degradation efficiency of Tpy-PCBA COF-activated PMS for pollutant BPA in Example 1 of this invention is shown in Figure a: as shown in Figure a, Tpy-PCBA COF can hardly adsorb BPA; as shown in Figure b, after adding PMS to the system, 100% removal of BPA was achieved within 10 minutes, while the removal rate of BPA by Tpy-BD COF is less than 10%.

[0044] In Example 1, Tpy-PCBACOF was used with different ions such as Cl in the range of 0-5 mM. - SO4 2- H2PO4 - And the activity of PMS in degrading BPA under the influence of humic acid (HA), such as Figure 7 As shown, Tpy-PCBA COF can achieve 100% removal of BPA within 20 minutes in environments with inorganic anions and HA in water, demonstrating strong anti-interference performance.

[0045] Cyclic test results of Tpy-PCBA-activated PMS for BPA degradation are as follows: Figure 8 As shown, the Type-PCBA exhibits good reusability and cycle stability.

[0046] In Example 1, the BPA removal effect of Tpy-PCBA-activated PMS in different water bodies is as follows: Figure 9 As shown, the catalyst maintains high degradation activity in different water bodies, demonstrating its great potential and environmental application value in the remediation of organic pollutants in the aquatic environment.

[0047] A comparison of Example 1 and Comparative Example 1 shows that different raw materials have a significant impact on the structural morphology of the product. This invention uses specific raw materials, namely 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde, to prepare a specific nanorod structure with C and N elements uniformly distributed on the COF surface, resulting in high catalytic activity. However, after changing the raw materials, the obtained product essentially lacks catalytic activity.

[0048] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention.

Claims

1. A method for preparing a pyridine nitrogen-containing pyrene-based covalent organic framework material, characterized in that, The raw material of the organic framework material is 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,6-pyridine dicarboxaldehyde; the specific preparation steps are as follows: Step 1: a certain amount of 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,6-pyridine dicarboxaldehyde are dissolved in 1,4-dioxane and 1,3,5-trimethylbenzene, then a certain amount of acid catalyst is added, nitrogen is bubbled to remove air to obtain a mixture; the molar ratio of 1,3,6,8-tetra-(p-aminophenyl)-pyrene to 2,6-pyridine dicarboxaldehyde is 1:1.8-2; the volume ratio of 1,4-dioxane to 1,3,5-trimethylbenzene is 1:0.9-1; Step 2: the above mixture is transferred into a reaction kettle for sealed hydrothermal reaction, the hydrothermal temperature is 119-121℃, the hydrothermal time is 72-72.5h, and a pyridine nitrogen-containing pyrene-based covalent organic framework material with nanorod structure is obtained.

2. The method of claim 1, wherein: In step 1, the acid catalyst is 0.5-1mL of acetic acid with a concentration of 6M.

3. The method of claim 1, wherein: In step 1, the dissolution is ultrasonic dissolution, the time is 15-20min; nitrogen is bubbled to remove air, the time is 15-20min.

4. A pyridine nitrogen-containing pyrene-based covalent organic framework, characterized in that, The organic framework has a nanorod structure, and carbon and nitrogen elements are uniformly distributed on the material, and the organic framework is prepared by the preparation method of any one of claims 1-3.

5. A pyridine nitrogen-containing pyrene-based covalent organic framework according to claim 4 for use in the degradation of organic pollutants.

6. Use according to claim 5, characterized in that, The organic pollutants are bisphenol A.

7. Use according to claim 5 or 6, characterized in that, The pyridine nitrogen-containing pyrene-based covalent organic framework is used in an environment with an inorganic anion concentration of 0-5mM and a humic acid concentration of 0-5mg / L in water. The pyridine nitrogen-containing pyrene-based covalent organic framework is used in an environment with an inorganic anion concentration of 0-5mM and a humic acid concentration of 0-5mg / L in water.

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