Novel bipyridyl covalent organic framework material as well as preparation method and application thereof

Abstract

The invention relates to the field of adsorption separation, in particular to a novel bipyridyl covalent organic framework material as well as a preparation method and application thereof. The novel dipyridyl covalent organic framework material is prepared by introducing a dipyridyl group into the structure of the covalent organic framework material. The novel bipyridyl covalent organic framework material disclosed by the invention has the advantages of simplicity in preparation, high specific surface area, high porosity, high iodine adsorption performance and reproducibility. The novel bipyridyl covalent organic framework material disclosed by the invention is uniform and stable in structure and beneficial to large-scale adsorption; the iodine adsorption material also has excellent high chemical stability and thermal stability, can be used for iodine adsorption experiments at 75 DEG C, and is suitable for treating related radioactive accidents, environmental pollutants and other problems in practical fields.

Description

Technical Field

[0001] This invention relates to the field of adsorption separation, and in particular to a novel bipyridine-based covalent organic framework material, its preparation method, and its applications. Background Technology

[0002] Nuclear energy, as a highly efficient and low-carbon energy source, occupies an important position in the modern energy structure; however, its development has always been limited by the safe disposal of nuclear waste. Radioactive iodine (mainly including...) 129 I and 131 I) is a typical byproduct of nuclear fission, which has high mobility and biotoxicity, posing a long-term threat to public health and the ecological environment. 131 I has a shorter half-life (about 8 days), while 129 Iodine has an extremely long half-life (up to 15.7 million years), and both can pollute the environment through airborne diffusion or solid waste systems, and harm human health through the reproductive and metabolic systems, including increased risk of thyroid cancer, neonatal health problems, and ecosystem pollution. Therefore, the development of efficient and reliable iodine capture technology has become an urgent need in the field of nuclear safety.

[0003] Currently, the main methods for treating gaseous radioactive iodine include dry phase dust removal, deposition, membrane separation, and adsorption. Among these, adsorption is widely recognized as the most promising technology due to its simplicity, low cost, and suitability for dynamic enrichment processes. However, existing adsorbents still suffer from limitations such as limited adsorption capacity, insufficient stability, or complex preparation processes, making it difficult to meet the needs of high-performance iodine adsorbents in practical applications. Therefore, developing adsorbents with high specific surface area, adjustable pore structure, and excellent chemical stability to achieve efficient capture and long-term stable preservation of radioactive iodine is of great significance for promoting the safe utilization of nuclear energy and the prevention and control of environmental pollution. Summary of the Invention

[0004] Based on the above, this invention provides a novel bipyridine-based covalent organic framework material, its preparation method, and its application in iodine adsorption. The novel bipyridine-based covalent organic framework material (COF-TMBP) prepared by this invention possesses the advantages of high specific surface area, high porosity, and a high density of active pyridine groups that strongly interact with iodine molecules. COF-TMBP not only has advantages such as thermal stability, simple synthesis route, mild reaction conditions, and easy adsorption process, but also exhibits very high adsorption and regeneration performance in iodine vapor.

[0005] To achieve the above objectives, the present invention provides the following solution: One of the technical solutions of this invention is a novel bipyridine-based covalent organic framework material, the structural formula of which is shown below: .

[0006] The second technical solution of the present invention is a method for preparing the above-mentioned novel bipyridine-based covalent organic framework material, wherein 2,2',6,6'-tetramethyl-4,4'-bipyridine, 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde and a base are dissolved in a solvent and reacted to obtain the novel bipyridine-based covalent organic framework material.

[0007] The third technical solution of this invention is the application of the above-mentioned novel bipyridine-based covalent organic framework material in iodine adsorption.

[0008] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention successfully designed and prepared a novel bipyridine-based covalent organic framework material COF-TMBP. This COF material has the advantages of simple preparation, high specific surface area, high porosity, high adsorption performance, and recyclability. (2) The novel bipyridine-based covalent organic framework material COF-TMBP prepared by this invention has a uniform and stable structure, which is beneficial for large-scale adsorption; (3) COF-TMBP has excellent chemical and thermal stability and can perform iodine adsorption experiments at 75℃, making it suitable for dealing with practical problems such as radioactive accidents and environmental pollutants. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the synthetic route for the novel bipyridine-based covalent organic framework material COF-TMBP of this invention; Figure 2 This is the FT-IR image of the COF-TMBP prepared in Example 1 of this invention; Figure 3 This is a SEM schematic diagram of COF-TMBP in Embodiment 1 of the present invention; Figure 4 This is a TEM schematic diagram of the COF-TMBP in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the BET of COF-TMBP in Embodiment 1 of the present invention; Figure 6This is a schematic diagram of the TGA of COF-TMBP in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the adsorption kinetics of iodine by COF-TMBP prepared in Example 1 of the present invention; Figure 8 This is a test graph showing the adsorption cycle performance of iodine vapor by COF-TMBP prepared in Example 1 of this invention. Detailed Implementation

[0011] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0012] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0013] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0014] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0015] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0016] The present invention aims to propose a novel adsorbent material and its preparation method to overcome the technical bottlenecks in the adsorption of radioactive iodine in existing technologies, and to provide a more advanced and reliable solution for the treatment of radioactive iodine.

[0017] Covalent organic frameworks (COFs), as a novel type of porous organic framework material, possess advantages such as high crystallinity and tunable functionality, exhibiting excellent performance in adsorption separation, fluorescence detection, and electrochemistry. This invention constructs a novel bipyridine-based covalent organic framework material with high specific surface area, high porosity, and a high density of pyridine groups. In particular, the high density of pyridine groups exhibits a strong interaction with iodine, which is beneficial for improving the material's iodine adsorption performance. The COF material with a bipyridine structure synthesized in this invention is highly suitable for iodine adsorption applications and is applicable to addressing practical problems in areas such as radioactive accidents and environmental pollutants.

[0018] The first aspect of this invention provides a novel bipyridine-based covalent organic framework material, the structural formula of which is shown below: .

[0019] A second aspect of the present invention provides a method for preparing the above-mentioned novel bipyridine-based covalent organic framework material, wherein 2,2',6,6'-tetramethyl-4,4'-bipyridine, 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde and a base are dissolved in a solvent and reacted to obtain the novel bipyridine-based covalent organic framework material.

[0020] In some embodiments of the present invention, sonication is used to promote the dissolution of 2,2',6,6'-tetramethyl-4,4'-bipyridine, 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde and a base in a solvent. The present invention does not impose any particular limitation on the power of the ultrasound; any ultrasound power commonly used by those skilled in the art to promote dissolution can be employed.

[0021] In a preferred embodiment of the present invention, the molar ratio of 2,2',6,6'-tetramethyl-4,4'-bipyridine to 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde is 1:0.5-20.

[0022] In a preferred embodiment of the present invention, the alkali is sodium hydroxide; the concentration of the alkali in the solvent is 0.5-100 mg / ml.

[0023] In a preferred embodiment of the present invention, the solvent is a mixture of trimethylbenzene and methanol in a volume ratio of 1:0.1-20.

[0024] In a preferred embodiment of the present invention, the concentration of 2,2',6,6'-tetramethyl-4,4'-bipyridine in the solvent is 0.005-0.1 mol / L.

[0025] In a preferred embodiment of the present invention, the reaction temperature is 60℃-220℃ and the reaction time is 1-5 days.

[0026] In a preferred embodiment of the present invention, the reaction is further complicated by centrifugation, followed by washing and drying of the solid obtained by centrifugation.

[0027] In some embodiments of the present invention, the product is washed several times in sequence with DMF, THF, water and ethanol; the drying is specifically vacuum drying at 100°C.

[0028] The third aspect of this invention provides the application of the novel bipyridyl covalent organic framework material described above in iodine adsorption.

[0029] This invention introduces bipyridine groups into the structure of a covalent organic framework material for testing its iodine adsorption performance. Because COF-TMBP can form an ordered one-dimensional pore structure, and the high-density pyridine groups exhibit strong interactions with iodine, COF-TMBP possesses high iodine adsorption performance. Experiments demonstrate that COF-TMBP can efficiently adsorb iodine from iodine vapor, achieving an adsorption capacity as high as 9.27 g / g. COF-TMBP offers advantages such as simple preparation, high specific surface area, high porosity, high adsorption performance, and recyclability, making it particularly suitable for addressing practical problems related to radioactive accidents and environmental pollutants.

[0030] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0031] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] A schematic diagram of the synthetic route for the novel bipyridyl covalent organic framework material COF-TMBP in this invention is shown below. Figure 1 As shown.

[0033] Example 1: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (0.5 mmol, 106.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (40 ml), and methanol (40 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 180℃ for 3 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100℃ to obtain white COF-TMBP.

[0034] Figure 2 This is the FT-IR image of the COF-TMBP prepared in Example 1 of this invention; by Figure 2 It can be seen that the methyl peak of TMBP and the aldehyde peak of OHAT are transformed into the vinyl peak of COF-TMBP, indicating that COF-TMBP was successfully synthesized.

[0035] Figure 3 This is a SEM schematic diagram of COF-TMBP in Embodiment 1 of the present invention; by Figure 3 It can be seen that the SEM image of COF-TMBP exhibits a distinct multi-layered blocky structure.

[0036] Figure 4 This is a TEM schematic diagram of the COF-TMBP in Embodiment 1 of the present invention; by Figure 4 It can be seen that the TEM image of COF-TMBP also shows a two-dimensional layered morphological structure.

[0037] Figure 5 This is a schematic diagram of the BET operation of COF-TMBP in Embodiment 1 of the present invention; by Figure 5 As can be seen from the BET plot, COF-TMBP has a high specific surface area.

[0038] Figure 6 This is a schematic diagram of the TGA of COF-TMBP in Embodiment 1 of the present invention; by Figure 6 As can be seen from the TGA graph, COF-TMBP has high thermal stability.

[0039] Example 2: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (0.5 mmol, 106.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (30 ml), and methanol (30 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 180°C for 3 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the amount of tricresylbenzene added is 30 ml and the amount of methanol added is 30 ml).

[0040] Example 3: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (0.5 mmol, 106.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (20 ml), and methanol (60 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 180°C for 3 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the amount of tricresylbenzene added was 20 ml and the amount of methanol added was 60 ml).

[0041] Example 4: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (1 mmol, 212.3 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (40 ml), and methanol (40 ml) were added and sonicated for a period of time (approximately 15 minutes). The reaction mixture was dissolved in an oven at 180°C for 3 days. After the reaction was completed, the mixture was cooled and centrifuged. It was washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the amount of TMBP added was 1 mmol).

[0042] Example 5: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (1 mmol, 212.3 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (1 mmol, 620.4 mg), sodium hydroxide (350 mg), trimethylbenzene (40 ml), and methanol (40 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 180°C for 3 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the amount of TMBP added is 1 mmol and the amount of OHAT added is 1 mmol).

[0043] Example 6: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (0.5 mmol, 106.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (700 mg), trimethylbenzene (40 ml), and methanol (40 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 180°C for 3 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the amount of sodium hydroxide added is 700 mg).

[0044] Example 7: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (0.5 mmol, 106.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (40 ml), and methanol (40 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 120°C for 3 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the reaction system was reacted in an oven at 120°C).

[0045] Example 8: Preparation of COF-TMBP In a 100 ml reactor, 2,2',6,6'-tetramethyl-4,4'-bipyridine (TMBP) (0.5 mmol, 106.2 mg), 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde (OHAT) (0.5 mmol, 310.2 mg), sodium hydroxide (350 mg), trimethylbenzene (40 ml), and methanol (40 ml) were added and sonicated for a period of time (approximately 15 minutes). (min) until dissolved, then the reaction system was reacted in an oven at 180°C for 2 days. After the reaction was completed, it was cooled and centrifuged, washed 3 times with DMF, 3 times with THF, 3 times with water, and 3 times with ethanol. It was then vacuum dried at 100°C to obtain white COF-TMBP (i.e., the only difference from Example 1 is that the reaction system was reacted in an oven for 2 days).

[0046] Test Example 1: Adsorption of Iodine Vapor by COF-TMBP Before the experiment, 0.01 g of the COF-TMBP samples prepared in Examples 1-8 were added to 20 ml sample bottles and placed in a vacuum oven for thorough vacuum degassing and drying (100℃, 2-4 hours). Then, excess iodine was added to a sealable glass container, the sample bottles were placed in the glass container, sealed, and heated in a 75℃ oven. The bottles were removed at intervals and cooled to room temperature. The changes in the mass of COF-TMBP before and after iodine adsorption were measured.

[0047] Figure 7 This is a schematic diagram of the adsorption kinetics of iodine by COF-TMBP prepared in Example 1 of this invention; Figure 7 It can be seen that iodine adsorption increases linearly in the first 3 hours and reaches adsorption saturation in about 6 hours. This shows that the COF-TMBP in Example 1 has very high adsorption performance and a very fast adsorption rate for iodine, with an adsorption capacity of up to 9.27 g / g. This invention not only develops a novel bipyridine-based covalent organic framework material, but also exhibits high adsorption performance for iodine.

[0048] Table 1. Iodine adsorption capacity of COF-TMBP in Examples 1-8

[0049] Test Example 2: Cyclic Performance Test of Iodine Vapor Adsorption by Regenerated COF-TMBP Following the method described in Test Example 1, COF-TMBP from Example 1 was subjected to an iodine adsorption test. 300 mg of COF-TMBP after adsorbing iodine vapor (denoted as I2-COF-TMBP) was then stirred in 500 ml of ethanol at room temperature for 12 hours, washed three times, and filtered. The COF-TMBP was then vacuum dried at 100°C, and the weight change before and after iodine desorption was measured. The desorbed material was reused in the iodine adsorption experiment, with at least six cycles performed. The results are as follows: Figure 8 As shown.

[0050] Depend on Figure 8 It can be seen that after six cycles of adsorption in iodine vapor, COF-TMBP can still maintain more than 99% of its initial maximum adsorption capacity.

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A novel bipyridyl covalent organic framework material, characterized in that, The structural formula is as follows: 。 2. A method for preparing the novel bipyridyl covalent organic framework material according to claim 1, characterized in that, The novel bipyridine-based covalent organic framework material was obtained by reacting 2,2',6,6'-tetramethyl-4,4'-bipyridine, 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde and a base in a solvent.

3. The preparation method according to claim 2, characterized in that, The molar ratio of 2,2',6,6'-tetramethyl-4,4'-bipyridine to 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxane-octadecene-2,3,13,14-tetramethyl)tetrabenzaldehyde is 1:0.5-20.

4. The preparation method according to claim 2, characterized in that, The alkali is sodium hydroxide; the concentration of the alkali in the solvent is 0.5-100 mg / ml.

5. The preparation method according to claim 2, characterized in that, The solvent is a mixture of trimethylbenzene and methanol in a volume ratio of 1:0.1-20.

6. The preparation method according to claim 2, characterized in that, The concentration of the 2,2',6,6'-tetramethyl-4,4'-bipyridine in the solvent is 0.005-0.1 mol / L.

7. The preparation method according to claim 2, characterized in that, The reaction temperature is 60℃-220℃, and the reaction time is 1-5 days.

8. The preparation method according to claim 2, characterized in that, The reaction also includes centrifugation, followed by washing and drying of the solid obtained from centrifugation.

9. The application of the novel bipyridyl covalent organic framework material as described in claim 1 in iodine adsorption.

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