Preparation method and application of pyrenyl covalent organic framework material containing pyridine nitrogen

Abstract

The invention discloses a preparation method and application of a pyrenyl covalent organic framework material containing pyridine nitrogen. The material has good application in the aspect of activating potassium monopersulfate (PMS) to degrade organic pollutants. The preparation method of the pyrenyl covalent organic framework material containing pyridine nitrogen comprises the following steps: taking 1, 3, 6, 8-tetra-(p-aminophenyl)-pyrene and 2, 6-pyridinedicarboxaldehyde as synthesis precursors, and carrying out Schiff base reaction to obtain the pyrenyl covalent organic framework material containing pyridine nitrogen. By introducing a pyridine nitrogen structure, the PMS activation capacity is remarkably improved, the efficient catalytic degradation capacity on bisphenol A is shown, meanwhile, the material is stable in property, does not generate secondary pollution, can be recycled, and has important application value and application prospects in the aspect of organic pollutant degradation.

Description

Technical Field

[0001] The invention relates to a preparation method of a pyridine nitrogen-containing pyrene-based covalent organic framework material and application thereof in activating PMS to degrade organic pollutants, belonging to the technical field of materials and advanced oxidation. Background Art

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

[0003] Traditional methods for treating organic pollutants, such as physical adsorption and biodegradation, have certain limitations. Physical adsorption only transfers pollutants from one phase to another and cannot completely degrade them; biodegradation is limited by environmental conditions and microbial adaptability, and the treatment efficiency is low. Advanced oxidation technology based on PMS can effectively remove organic pollutants due to its strong oxidizing properties. Transition metals are widely used to activate PMS, but there is a problem of secondary pollution caused by metal ion leaching. Metal-free carbon materials can activate PMS to remove pollutants, but the activation effect is not ideal and the efficiency is low.

[0004] Covalent organic framework materials (COFs) are a new type of porous crystalline materials. They have a highly ordered structure, adjustable pore size and functionalized skeleton, which can provide abundant active sites. They show great potential in the field of activating persulfate to degrade organic pollutants. The use of COFs to activate persulfate to degrade pollutants can make full use of their advantages such as large specific surface area, and can expose more active sites to activate PMS. COFs materials are easy to synthesize and do not produce secondary pollution. They are green and environmentally friendly catalysts and are expected to become ideal materials for activating PMS to remove antibiotics. They have important theoretical and practical value in the field of environmental remediation. Summary of the invention

[0005] The invention discloses a preparation method and application of a pyridine nitrogen-containing pyrene-based covalent organic framework, 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: using 1,3,6,8-tetra-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde as synthesis precursors, and obtaining the pyridine nitrogen-containing pyrene-based covalent organic framework material by Schiff base reaction. The material is synthesized by a hydrothermal method, and the obtained material has a nanorod-like structure. The introduction of pyridine nitrogen increases the active sites of the material, and by introducing the pyridine nitrogen structure, the ability to activate PMS is significantly improved. The material can effectively activate PMS to generate active species to degrade organic pollutants, and shows efficient catalytic degradation ability for bisphenol A. At the same time, the material has stable properties and will not produce secondary pollution, and can be recycled, and has important application value and application prospects in degrading organic pollutants.

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

[0007] The first step is to add a certain amount of 1,3,6,8-tetrakis-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde into 1,4-dioxane and 1,3,5-trimethylbenzene to dissolve them, then add a certain amount of acid catalyst, and introduce nitrogen bubbling to expel air to obtain a mixture;

[0008] Step 2: Transfer the above mixture into a reactor for a closed hydrothermal reaction to obtain a nanorod-like structured pyridine nitrogen-containing pyrene-based covalent organic framework material.

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

[0010] Further, 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; and the air is expelled by nitrogen bubbling for 15-20 minutes.

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

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

[0015] An application of the pyridine nitrogen-containing pyrene-based 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-based covalent organic framework in an environment where inorganic anions (0-5mM) and humic acid (0-5mg / L) exist in water.

[0016] The purpose of the present invention is to provide the application of the Ty-PCBA COF material as an advanced oxidation catalyst for catalytic activation of PMS to improve 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:

[0019] 1) The present invention prepares for the first time a pyridine nitrogen-containing pyrene-based covalent organic framework, which has strong anti-interference ability and oxidation ability in the advanced oxidation catalytic degradation of organic pollutants, and at the same time has high catalytic degradation activity and cyclic stability. The metal-free material will not cause secondary pollution, and has high application prospects in the field of pollutant degradation.

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

[0021] 3) The large specific surface area and abundant active sites increase the contact between the active sites and PMS, making PMS more easily oxidized. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the XRD pattern of the product of Example 1;

[0023] Figure 2 FTIR graph of the product of Example 1 compared with the synthetic precursor;

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

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

[0026] Figure 5 The N of the pyridine nitrogen-containing pyrene-based covalent organic framework material obtained in Example 1 at 77K 2 Adsorption isotherm and pore size distribution diagram;

[0027] Figure 6 This is the Fenton-like degradation activity diagram of bisphenol A of the products of Example 1 and Comparative Example 1;

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

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

[0030] Fig. 9 This is the activity diagram of the product of Example 1 in degrading bisphenol A under different water environments. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with specific embodiments. However, the protection scope of the present invention is not limited to the following embodiments, and any non-essential adjustments and modifications made to the present invention based on the above invention content still fall within the protection scope of the present invention.

[0032] Example 1

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

[0034] Comparative Example 1

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

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

[0037] The FTIR images 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, Ph-NH 2 (3020cm -1 ) and NH(3342cm -1 ) and C=O in PCBA (1720cm -1 ) and other precursors decreased sharply, and at the same time, a C=N bond (1627 cm -1 ), indicating that the imine bond was successfully formed through the Schiff base reaction and Tpy-PCBA COF was synthesized.

[0038] TEM images of the products of Example 1 and Comparative Example 1 are as follows: 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-PCBA COF has a nanorod structure, and C and N elements are evenly distributed on the COF surface, while Tpy-BD COF has a spherical structure, and Tpy-PCBA COF is more likely to contact with PMS. It can be seen that after the raw materials are replaced, the product structure has changed significantly, and the specific raw materials of the present invention have a very important influence on the structure of the product.

[0039] Figure 5 The nitrogen adsorption-desorption diagram and pore size distribution diagram of the product of Example 1 are shown in FIG. Figure 5 It can be seen that the pore size of Tpy-PCBA COF is 10.312nm. After analysis and calculation, its surface area is 403.005m 2 ·g -1 It can be seen that the Tpy-PCBA COF has a large specific surface area, which is beneficial to increase the contact area between COF and pollutants and increase the reaction sites and active sites for activating PMS.

[0040] Performance Testing

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

[0042] Weigh 10 mg of each product obtained in Example 1 and Comparative Example 1, add them to a 10 mg / L bisphenol A (BPA) solution, and stir the suspension with a magnetic stirrer. After reaching adsorption equilibrium, add 5 mM PMS. In order to obtain degradation kinetic data, take out 1 mL of the solution at a specified time, filter it with a syringe with a 0.45 μm filter head, and immediately add an equal volume of Na 2 S 2 O 3The reaction was terminated. The concentration of the remaining BPA was then analyzed using high performance liquid chromatography (HPLC, Shimadzu 2030C). After the reaction was completed, the catalyst was centrifuged and washed, and then a cyclic stability test was performed.

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

[0044] In Example 1, Ty-PCBACOF was exposed to different ions such as Cl at 0-5 mM. - 、SO 4 2- , H 2 PO 4 - , and the activation of PMS to degrade BPA under the influence of humic acid (HA), such as Figure 7 As shown in the figure, Ty-PCBA COF can achieve 100% removal of BPA within 20 minutes in an environment of inorganic anions and HA in water, and has strong anti-interference performance.

[0045] The cycle test results of Tpy-PCBA activated PMS to degrade BPA are as follows Figure 8 As shown, it can be seen that Ty-PCBA has good reusability and cycle stability.

[0046] The removal effect of BPA by activating PMS in different water bodies by Ty-PCBA in Example 1 is as follows: Fig. 9 As shown, the catalyst still maintains a high degradation activity in different water bodies, demonstrating its great potential and environmental application value in the remediation of organic pollutants in aquatic environments.

[0047] From the comparison between Example 1 and Comparative Example 1, it can be seen that different raw materials have a very huge impact on the structural morphology of the product. The present invention uses specific raw materials, namely 1,3,6,8-tetrakis-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde to prepare a specific nanorod-like structure, and the C and N elements are evenly distributed on the COF surface, resulting in a higher catalytic activity. After the raw materials are replaced, the obtained product has basically no catalytic activity.

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

Claims

1. A method for preparing a pyridine nitrogen-containing pyrene-based covalent organic framework material, characterized in that: The raw materials of the organic framework material are 1,3,6,8-tetrakis-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde; the specific preparation steps are as follows: The first step is to add a certain amount of 1,3,6,8-tetrakis-(p-aminophenyl)-pyrene and 2,6-pyridinedicarboxaldehyde into 1,4-dioxane and 1,3,5-trimethylbenzene to dissolve them, then add a certain amount of acid catalyst, and introduce nitrogen bubbling to expel air to obtain a mixture; Step 2: Transfer the above mixture into a reactor for a closed hydrothermal reaction to obtain a nanorod-like structured pyridine nitrogen-containing pyrene-based covalent organic framework material.

2. The preparation method according to claim 1, characterized in that: In the first step, the molar ratio of 1,3,6,8-tetrakis-(p-aminophenyl)-pyrene to 2,6-pyridinedicarboxaldehyde is 1:1.8-2.

3. The preparation method according to claim 1, characterized in that: In the first step, the acid catalyst is 0.5-1 mL of 6M acetic acid.

4. The preparation method according to claim 1, characterized in that: In the first step, the volume ratio of 1,4-dioxane to 1,3,5-trimethylbenzene is 1:0.9-1.

5. The preparation method according to claim 1, characterized in that: In the first step, the dissolution is performed by ultrasonic dissolution for 15-20 minutes; and the air is expelled by nitrogen bubbling for 15-20 minutes.

6. The preparation method according to claim 1, characterized in that: In the second step, the hydrothermal temperature is 119-121°C, and the hydrothermal time is 72-72.5h.

7. A pyridine nitrogen-containing pyrenyl covalent organic framework, characterized in that: The organic framework has a nanorod-like structure, and carbon and nitrogen elements are evenly distributed on the material. The organic framework is prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the pyridine nitrogen-containing pyrenyl covalent organic framework as claimed in claim 7 in the degradation of organic pollutants.

9. The use according to claim 8, characterized in that: The organic pollutant is bisphenol A.

10. The use according to claim 8 or 9, characterized in that: The pyridine nitrogen-containing pyrene-based covalent organic framework is used in an environment where the inorganic anion concentration in water is 0-5 mM and the humic acid concentration is 0-5 mg / L.

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