A covalent organic framework material and a preparation method and application thereof

Abstract

This invention belongs to the field of porous organic materials technology, specifically relating to a covalent organic framework material, its preparation method, and its application. It is obtained by a high-temperature ammonia-aldehyde condensation reaction of 1,3,5-phenyltricarboxyhydrazide and 2,5-divinyl-1,4-phenylenedialdehyde, using azobisisobutyronitrile (AIBN) as an initiator, through the reaction of 1,2-ethylenedithiol and COF... BTH‑DVa The vinyl groups on the surface undergo a click reaction, achieving anchorage of thiol groups on the COF surface and the inner walls of the pores; wherein, COF BTH‑DVa The abundance of -N-N- sites and the post-modified thiol groups will endow SH-COF with... BTH‑DVa Multiple HMIs adsorption sites enable SH-COF BTH‑DVa The material exhibits excellent adsorption performance for HMIs, specifically in SH-COF. BTH‑DVa The material can realize the extraction of Pb from aqueous solution. 2+ It can remove efficiently and quickly.

Description

Technical Field

[0001] This invention belongs to the field of porous organic materials technology, specifically relating to a covalent organic framework material, its preparation method, and its application. Background Technology

[0002] Covalent organic frameworks (COFs) are porous crystalline polymers composed of organic molecules linked by covalent bonds. Due to their large specific surface area, ordered pore channels, excellent thermal and chemical stability, ease of functionalization, and tunable framework, they are widely used in adsorption, energy storage, drug delivery, and catalysis. Because COFs show promising application prospects in the adsorption and removal of heavy metal ions (HMIs), many novel COFs have been designed and synthesized for HMI adsorption and removal. However, the limited number of adsorption functional sites severely restricts the adsorption performance of COFs for HMIs. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing covalent organic framework materials, so that the prepared COFs have multiple adsorption functional sites, thereby effectively avoiding the problem of poor adsorption performance of COFs due to insufficient surface adsorption sites, and providing a technical basis for the rapid and efficient adsorption and removal of HMIs by COFs.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a covalent organic framework material includes the following steps:

[0006] (1) First, 1,3,5-benzenetricarboxyhydrazide (BTH) and 2,5-divinyl-1,4-benzenedialdehyde (DVa) were independently dispersed in a mixed solution of 1,4-dioxane and mesitylene, and then dissolved by sonication.

[0007] Subsequently, the two solutions were transferred to test tubes, sonicated until homogeneous, and then acetic acid solution was added.

[0008] After degassing through several (three or more) freeze-thaw cycles, the test tube (Shrek tube) is placed in an oil bath at 120℃~125℃ for reaction.

[0009] (2) The product of the oil bath reaction was washed with N,N-dimethylformamide, the precipitate obtained by washing was soaked in tetrahydrofuran, and then dried under vacuum to obtain (yellow powder) COF. BTH-DVa Material;

[0010] (3) COFBTH-DVa The material and azobisisobutyronitrile (AIBN) are transferred into a clean test tube, then 1,2-ethanedithiol is added, the stirring reaction is carried out at 80-85°C in a nitrogen atmosphere, the stirring reaction product is washed with acetone, the precipitate obtained by washing is vacuum dried, and SH-COF is obtained BTH-DVa Material.

[0011] In a preferred example, in step (1), the mass ratio of 1,3,5-benzene triformhydrazide to 2,5-divinyl-1,4-benzene dicarboxaldehyde is 25-26:27-28, and the mass-volume ratio of the mixed solution of 1,3,5-benzene triformhydrazide to 1,4-dioxane and mesitylene is 42g-43g:1L.

[0012] In a preferred example, the volume ratio of 1,4-dioxane to mesitylene is 1:1.

[0013] In a preferred example, in step (1), the mass-volume ratio of 1,3,5-benzene triformhydrazide to acetic acid solution is 42g-43g:1L, and the concentration of the acetic acid solution is 6mol / L.

[0014] In a preferred example, in step (1), the oil bath reaction time is 72h-75h.

[0015] In a preferred example, in step (2), the tetrahydrofuran soaking time is 8h-12h.

[0016] In a preferred example, in step (3), the COF BTH-DVa The mass ratio of the material to azobisisobutyronitrile is 4:1, and the COF BTH-DVa The mass-volume ratio of the material to 1,2-ethanedithiol is 25g:1L.

[0017] In a preferred example, in step (3), the stirring reaction time is 48h-50h.

[0018] By the above method, SH-COF BTH-DVa Material is successfully prepared. BTH-DVa The material is obtained by ammonia aldehyde condensation reaction of 1,3,5-benzene triformhydrazide and 2,5-divinyl-1,4-benzene dicarboxaldehyde at high temperature, and azobisisobutyronitrile (AIBN) is used as an initiator, 1,2-ethanedithiol and COF BTH-DVa The click reaction of the vinyl group on the surface of the COF realizes the anchoring of the mercapto group on the surface and the inner wall of the COF BTH-DVa The abundant -N-N- sites of the COF BTH-DVa and the post-modified mercapto group will endow the SH-COF BTH-DVaThe material presents excellent adsorption performance to the HMI, which is specifically shown in SH-COF BTH-DVa The material can realize efficient and rapid removal of Pb 2+ in an aqueous solution.

[0019] Based on a total inventive concept, another object of the present application is to provide the covalent organic framework material with multiple adsorption sites prepared by the preparation method and the application thereof in adsorption and removal of heavy metal ions, preferably adsorption and removal of Pb 2+ in an aqueous solution.

[0020] Compared with the prior art, the covalent organic framework material SH-COF BTH-DVa prepared by the method of the present application has multiple adsorption functional sites, which endows the COF with excellent heavy metal ion adsorption performance and realizes rapid and efficient removal of heavy metal ions in the environment. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The scanning electron microscope image (scale: 1 μm, detection environment: thermoluminescence detector, high voltage 10.00KV, working distance 5.0mm, magnification 120000 times, light spot 4.0) of SH-COF BTH-DVa prepared in Example 1.

[0022] Figure 2 The Fourier infrared curves of BTH, DVa, COF BTH-DVa and SH-COF BTH-DVa .

[0023] Figure 3 The adsorption isotherms of COF BTH-DVa and SH-COF BTH-DVa to Pb 2+ .

[0024] Figure 4 The adsorption equilibrium data and Langmuir adsorption model fitting curves of COF BTH-DVa and SH-COF BTH-DVa to Pb 2+ .

[0025] Figure 5 The adsorption kinetics performance curves of COF BTH-DVa and SH-COF BTH-DVa to Pb 2+ .

[0026] Figure 6 The pseudo-second-order kinetics fitting diagrams of COF BTH-DVa and SH-COF BTH-Dva to Pb 2+ . DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described with specific embodiments. It should be noted that the following described embodiments or technical features can be combined with each other to form new embodiments without conflict. In the present application, unless specified, all the parts and percentages are mass units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are the conventional methods in the art, unless specified.

[0028] As used herein, the terms "comprises", "comprising", "includes", "including", or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0029] When a range, preferably a range, or a range defined by a series of upper preferred values and lower preferred values of other values or parameters is expressed, it should be understood that all ranges formed by any one pair of range upper limit or preferred value and any range lower limit or preferred value are specifically disclosed, regardless of whether the range is disclosed separately. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0030] Example 1

[0031] A method for preparing a covalent organic framework material, comprising the following steps:

[0032] (1) First, 25.2 mg of 1,3,5-benzene trihydrazide (BTH) and 27.9 mg of 2,5-divinyl-1,4-benzene dicarboxaldehyde (DVa) were dissolved in a mixed solution of 3 mL of 1,4-dioxane and mesitylene, respectively, and ultrasonically dissolved;

[0033] Among them, the volume ratio of 1,4-dioxane and mesitylene is 1:1;

[0034] Then, the two solutions were transferred to a Schlenk tube, and after ultrasonic homogenization, 0.6 mL of 6 mol / L acetic acid solution was added;

[0035] The reaction solution was degassed by three freeze-thaw cycles, and then was placed in an oil bath at 120°C for 72h of reaction;

[0036] (2) The product of the oil bath reaction was washed with N,N-dimethylformamide, and the precipitate obtained by washing was soaked in 10 mL of tetrahydrofuran, and after 12h, the precipitate was centrifuged and vacuum dried to obtain COF BTH-DVa material;

[0037] (3) 100mg of COF BTH-DVa material and 25mg of azobisisobutyronitrile (AIBN) were transferred into a clean and dry 25mL Schlenk tube, followed by the addition of 4mL of 1,2-ethanedithiol, and then was stirred at 80°C for 48h in a nitrogen-filled atmosphere, and then the product of the stirring reaction was washed with acetone, and the precipitate obtained by washing was vacuum dried to obtain SH-COF BTH-DVa material.

[0038] Example 2

[0039] A method for preparing a covalent organic framework material, comprising the following steps:

[0040] (1) 50mg of 1,3,5-benzene trihydrazide (BTH) and 56mg of 2,5-divinyl-1,4-benzene dicarboxaldehyde (DVa) were respectively dissolved in 6mL of a mixed solution of 1,4-dioxane and mesitylene, and were ultrasonically dissolved;

[0041] Among them, the volume ratio of 1,4-dioxane and mesitylene is 1:1;

[0042] Then the two solutions were transferred into a Schlenk tube, and after ultrasonic homogenization, 0.6mL of 6mol / L acetic acid solution was added;

[0043] The reaction solution was degassed by three freeze-thaw cycles, and then was placed in an oil bath at 120°C for 72h of reaction;

[0044] (2) The product of the oil bath reaction was washed with N,N-dimethylformamide, and the precipitate obtained by washing was soaked in 10 mL of tetrahydrofuran, and after 12h, the precipitate was centrifuged and vacuum dried to obtain COF BTH-DVa material;

[0045] (3) 100mg of COF BTH-DVaThe material and 25 mg of azobisisobutyronitrile (AIBN) were transferred into a clean and dry 50 mL Schlenk tube, followed by the addition of 10 mL of 1,2-ethanedithiol, and the reaction was stirred at 80°C for 48 h in a nitrogen-filled atmosphere. The product of the stirred reaction was washed with acetone, and the obtained precipitate was vacuum dried to obtain SH-COF BTH-DVa Material.

[0046] Example 1

[0047] 10 mg of SH-COF prepared in Example 1 BTH-DVa was added to an aqueous solution containing 200 mg / L Pb 2+ and stirred for 12 h to allow adsorption to reach equilibrium.

[0048] Example 1

[0049] The SH-COF prepared in Example 1 BTH-DVa was subjected to morphology characterization, and the scanning electron microscope image showed that the SH-COF BTH-DVa was a tubular structure material with uniform growth of fine strips on the surface (as shown in Figure 1 ).

[0050] Example 1

[0051] The Fourier infrared curve (as shown in Figure 2 ) revealed that the aldehyde group characteristic peak (C=O, 1685 cm -1 ) of 2,5-divinyl-1,4-benzene dicarboxaldehyde (DVa) and the amino group characteristic peak (N-H, 3298 cm -1 ) of 1,3,5-benzene triformhydrazide (BTH) disappeared on the COF BTH-DVa curve, while the COF BTH-DVa had a clear characteristic peak of -C=N- at 1659 cm -1 , indicating that the amine aldehyde condensation reaction of DVa and BTH had successfully generated COF BTH-DVa ;

[0052] In addition, the SH-COF BTH-DVa retained the characteristic peaks of the COF BTH-DVa , and had a characteristic peak of S-H at 2348 cm -1 , proving that the thiol group had been successfully modified to the surface of the COF BTH-DVa .

[0053] Figure 3 and Figure 4 revealed that the SH-COF BTH-DVa and the COF BTH-DVa had a good adsorption effect on Pb 2+The adsorption process conforms to the Langmuir adsorption model, indicating that they are effective against Pb. 2+ It belongs to surface monolayer adsorption, and SH-COF BTH-DVa and COF BTH-DVa For Pb 2+ The maximum adsorption capacities were 1474 mg / g and 910 mg / g, respectively. These results fully demonstrate that SH-COF... BTH-DVa The synergistic effect of multiple adsorption sites of -NN- and -SH can indeed effectively enhance the adsorption of Pb by COFs. 2+ Adsorption capacity.

[0054] Figure 5 and Figure 6 The results showed that SH-COF BTH-DVa and COF BTH-DVa For Pb 2+ The adsorption follows second-order kinetics, proving that the adsorption process is chemisorption.

[0055] The above embodiments are merely preferred embodiments of the present invention. Any simple modifications, alterations, and substitutions made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. Use of a covalent organic framework material for the removal of heavy metal ions by adsorption, characterized in that, Removal of Pb 2+ from aqueous solutions by adsorption; The preparation method of the covalent organic framework material comprises the following steps: (1) independently dispersing 1,3,5-benzene triformhydrazide and 2,5-divinyl-1,4-benzene dicarboxaldehyde in a mixed solution of 1,4-dioxane and mesitylene respectively, and ultrasonically dissolving; Subsequently, the two solutions are transferred into test tubes, and after being uniformly ultrasonically treated, an acetic acid solution is added; After several freeze-thaw cycles and degassing, the test tubes are placed in an oil bath at a temperature of 120-125 DEG C for reaction; (2) The product of the oil bath reaction is washed with N,N-dimethylformamide, the precipitate obtained by washing is soaked with tetrahydrofuran, and then vacuum dried to obtain COF BTH-DVa material; (3) COF BTH-DVa material and azobisisobutyronitrile were transferred into a clean test tube, then 1,2-ethanedithiol was added, the stirring reaction was carried out at a temperature of 80-85°C in an atmosphere filled with nitrogen protection, the product of the stirring reaction was washed with acetone, the precipitate obtained by washing was vacuum dried to obtain SH-COF BTH-DVa material, the covalent organic framework material was SH-COF BTH-DVa material.

2. Use according to claim 1, characterized in that, In step (1), the mass ratio of 1,3,5-benzene triformhydrazide to 2,5-divinyl-1,4-benzene dicarboxaldehyde is 25-26:27-28, and the mass-volume ratio of 1,3,5-benzene triformhydrazide to the mixed solution of 1,4-dioxane and mesitylene is 42g-43g:1L.

3. Use according to claim 2, characterized in that, The volume ratio of 1,4-dioxane to mesitylene is 1:

1.

4. Use according to claim 1, characterized in that, In step (1), the mass-volume ratio of 1,3,5-benzene triformhydrazide to the acetic acid solution is 42g-43g:1L, and the concentration of the acetic acid solution is 6mol / L.

5. The use according to claim 1, characterized in that, In step (1), the time for oil bath reaction is 72h-75h.

6. Use according to claim 1, characterized in that, In step (2), the time for tetrahydrofuran soaking is 8h-12h.

7. The use according to claim 1, characterized in that, Step (3), COF BTH-DVa Material to azobisisobutyronitrile mass ratio of 4:1, COF BTH-DVa Material to 1,2-ethanedithiol mass volume ratio of 25 g:1 L.

8. The use according to claim 1, characterized in that, In step (3), the time for stirring reaction is 48h-50h.

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