Crown ether covalent organic framework material and preparation method and application thereof

Abstract

The invention relates to a crown ether covalent organic framework material as well as a preparation method and application thereof. The preparation method comprises the following steps: dissolving a crown ether monomer and an amino monomer in an o-dichlorobenzene solvent, adding a catalyst acetic acid aqueous solution, and uniformly dispersing to form a reaction solution; the method comprises the following steps: freezing a reaction solution through a liquid nitrogen bath, vacuumizing, filling nitrogen, carrying out a heating reaction, and carrying out post-treatment operations such as washing and drying on a reaction product, so as to obtain the crown ether covalent organic framework material BADT-DB18C6-COF. The crown ether covalent organic framework material is formed by condensation of a crown ether aldehyde monomer and an amino monomer, the crown ether monomer is 4, 4 ', 4' ', 4 '''-(6, 7, 9, 10, 17, 18, 20, 21-octahydrodibenzo [B, K] [1, 4, 7, 10, 13, 16] hexaoxacyclo octadecene-2, 3, 13, 14-tetrayl) tetrabenzaldehyde, and the crown ether monomer is 4, 4 ', 4' ', 4'''-(6, 7, 9, 10, 17, 18, 20, 21-octahydrodibenzo [B, K] [1, 4, 7, 10, 13, 16] hexaoxacyclo octadecene-2, 3, 13, 14-tetrayl) tetrabenzaldehyde. The amino monomer is 4 ', 5'-bis (4-aminophenyl)-[1, 1 ': 2', 1 ''-terphenyl]-4, 4''-diamine. The crown ether covalent organic framework material BADT-DB18C6-COF prepared by the invention is mainly used as an adsorbent, is used for adsorbing and recovering uranium, thorium and americium ions from a solution, shows good adsorption capacity on radionuclides U-238, Th-232 and Am-243, and is particularly suitable for the field of spent fuel post-treatment in the nuclear industry.

Description

Technical Field

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

[0002] The rapid development of the nuclear energy industry has led to increasingly serious environmental release problems of radioactive nuclides (such as uranium, thorium, and americium). These nuclides have long half-lives and high biotoxicity, necessitating the use of highly efficient adsorption materials to address their pollution issues. Traditional adsorbents (such as activated carbon and zeolite) are limited by low selectivity and finite adsorption capacity. COFs, due to their designable structure, high stability, and functional diversity, have become a research hotspot in the field of radionuclide adsorption.

[0003] Covalent organic frameworks (COFs) not only possess stable and tunable porous structures, but also demonstrate potential in chemical adsorption and separation due to their highly designable functional group characteristics. The high crystallinity of COFs endows them with a regular and ordered pore structure, while the precise controllability of active sites within the framework provides unique advantages for applications such as catalysis, adsorption, and separation. Based on the successful application of COFs in the field of adsorbents, this invention develops a method for preparing and applying a radionuclide adsorbent material. Summary of the Invention

[0004] The purpose of this invention is to provide a crown ether-based covalent organic framework material, its preparation method, and its application. The prepared crown ether-based covalent organic framework material BADT-DB18C6-COF is used as an adsorbent for the efficient recovery of uranium ions, thorium ions, and americium ions from solution, exhibiting excellent adsorption performance. Furthermore, the preparation method is low in cost, simple to operate, and produces minimal pollution.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a crown ether-based covalent organic framework material, wherein the crown ether-based covalent organic framework material is BADT-DB18C6-COF, and the BADT-DB18C6-COF is formed by the condensation of a crown ether monomer and an amino monomer, wherein the crown ether monomer is 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 the amino monomer is 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine;

[0006] The BADT-DB18C6-COF has the following structural formula:

[0007]

[0008] The present invention also provides a method for preparing the crown ether-based covalent organic framework material, the method comprising the following steps:

[0009] S1. Preparation of reaction solution: Dissolve 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine and 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 in o-dichlorobenzene solvent, then add acetic acid solution and disperse evenly to obtain the reaction solution;

[0010] S2. Place the reaction solution in a liquid nitrogen bath for freezing, repeatedly evacuate and purge with nitrogen and seal the tube;

[0011] S3. Heating reaction. After the reaction is completed and cooled, the crown ether-based covalent organic framework material BADT-DB18C6-COF is obtained after washing and drying.

[0012] Further, step S1 includes the following specific steps: 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine and 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 are added to o-dichlorobenzene solvent and sonicated until dissolved; then acetic acid solution is added and sonicated again until acetic acid is evenly dispersed to obtain the reaction solution.

[0013] Further, in step S1, 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine and 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 are added to o-dichlorobenzene solvent and sonicated for 10-20 min until dissolved; then acetic acid solution is added and sonicated for another 5-10 min until the acetic acid is evenly dispersed to obtain the reaction solution.

[0014] Furthermore, in step S1, the reaction solution is prepared in a 10 ml Pyrex tube;

[0015] The volume of the o-dichlorobenzene solvent is 1-2 ml.

[0016] Further, in step S1, the concentration of 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 in the reaction solution is 0.012-0.024 mol / L.

[0017] Further, in step S1, the molar ratio of 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 to 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine is 1:1-1.3.

[0018] Furthermore, in step S1, the concentration of acetic acid in the reaction solution is 0.28-0.54 mol / L.

[0019] Furthermore, in step S2, the tube is sealed using a flame gun.

[0020] Furthermore, in step S2, the vacuuming-nitrogen filling process is repeated 3-5 times, with each vacuuming operation having a pressure of 3-5 Pa.

[0021] Furthermore, in step S3, the heating reaction is carried out in an oven at a temperature of 120℃-150℃ for a time of 3-5 days.

[0022] Furthermore, in the washing operation described in step S3, an anhydrous solvent is used for washing.

[0023] Furthermore, the anhydrous solvent is at least one of anhydrous tetrahydrofuran, anhydrous acetone, anhydrous methanol, and anhydrous N,N-dimethylacetamide.

[0024] Furthermore, step S3, the drying operation, is a heated vacuum drying process, wherein the temperature of the heated vacuum drying is 100-120℃ and the drying time is 6-12h.

[0025] This invention also provides an application of the crown ether-based covalent organic framework material, wherein the BADT-DB18C6-COF material is used to adsorb and recover radionuclides U-238, Th-232 and Am-243 from solution.

[0026] The beneficial effects of this invention are as follows: Using the crown ether-based covalent organic framework material, its preparation method, and its application provided by this invention, the crown ether monomer and amino monomer are dissolved in o-dichlorobenzene solvent, and an aqueous acetic acid catalyst is added and dispersed uniformly to form a reaction solution. The reaction solution is frozen in a liquid nitrogen bath, then evacuated and purged with nitrogen, and then heated to react. The reaction product is washed, dried, and other post-treatment operations to obtain the crown ether-based covalent organic framework material BADT-DB18C6-COF. The crown ether-based covalent organic framework material BADT-DB18C6-COF is synthesized by the condensation of a crown ether aldehyde monomer and an amino monomer. The crown ether monomer is 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 (DB18C6); the amino monomer is 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT). The crown ether-based covalent organic framework material BADT-DB18C6-COF prepared in this invention is mainly used as an adsorbent for the adsorption and recovery of uranium, thorium, and americium ions from solution. It exhibits good adsorption capacity for radionuclides U-238, Th-232, and Am-243, and is particularly suitable for spent fuel reprocessing in the nuclear industry. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the synthetic route for preparing the crown ether-based covalent organic framework material BADT-DB18C6-COF according to an embodiment of the present invention;

[0028] Figure 2 This is the X-ray crystal diffraction pattern of the BADT-DB18C6-COF material prepared in Example 1 of this invention;

[0029] Figure 3 This is an adsorption capacity diagram of BADT-DB18C6-COF prepared in Example 1 of the present invention for uranium ions under different nitric acid concentrations;

[0030] Figure 4 This is an adsorption capacity diagram of BADT-DB18C6-COF prepared in Example 1 of the present invention for thorium ions under different nitric acid concentrations. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be further described clearly and completely below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Based on the high crystallinity of COFs, which endows them with a regular and ordered pore structure, and the unique advantage of precisely controllable active sites in the framework, which can be applied to catalysis, adsorption, and separation, the inventors designed a technical solution for the enrichment of radionuclides such as uranium, thorium, and americium using COFs. By introducing 18-crown-6 into the main chain of COFs, the size coordination effect of the crown ether is utilized to significantly enhance the capture ability of target nuclides. This design can selectively adsorb uranyl ions (UO2) of specific sizes through the pore size sieving effect of the crown ether ring. 2+ ), Thorium ions (Th) 4+ ) and americium ions (Am 3+ Furthermore, the interlayer and pore interactions of COFs can be used to significantly enhance the coordination, electrostatic attraction, or redox reactions between nuclides, thereby achieving efficient and stable binding and thus greatly improving the adsorption capacity and selectivity of COFs for radionuclides in complex systems.

[0033] In the technical solution provided by the embodiments of the present invention, the crown ether monomer and the amino monomer are dissolved in o-dichlorobenzene solvent, ultrasonicated, and then an aqueous acetic acid catalyst is added; the mixture is frozen in a liquid nitrogen bath, then evacuated and purged with nitrogen, reacted at high temperature, and then washed, dried and other post-treatment operations are performed to obtain the crown ether-based covalent organic framework material BADT-DB18C6-COF; wherein, the crown ether monomer is 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 (DB18C6); the amino monomer is 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT). The crown ether-based covalent organic framework material BADT-DB18C6-COF prepared in this embodiment is mainly used as an adsorbent for the adsorption and recovery of uranium, thorium and americium ions from solution. It exhibits good adsorption capacity for radionuclides U-238, Th-232 and Am-243, and is particularly suitable for spent fuel reprocessing in the nuclear industry.

[0034] like Figure 1 As shown, this embodiment provides a crown ether-based covalent organic framework material.

[0035] A method for preparing BADT-DB18C6-COF, the method comprising the following steps:

[0036] S1. Preparation of reaction solution: Dissolve 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT) and 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 (DB18C6) in o-dichlorobenzene solvent, then add acetic acid solution and disperse evenly to obtain the reaction solution;

[0037] Optionally, step S1 includes the following specific steps: adding BADT and DB18C6 to o-dichlorobenzene solvent and sonicating until dissolved; then adding acetic acid solution and continuing sonication until acetic acid is evenly dispersed to obtain a reaction solution.

[0038] Specifically, in step S1, BADT and DB18C6 are added to o-dichlorobenzene solvent and sonicated for 10-20 minutes until dissolved; then acetic acid solution is added and sonicated for another 5-10 minutes until the acetic acid is evenly dispersed to obtain the reaction solution.

[0039] Specifically, in step S1, the reaction solution is prepared in a 10ml Pyrex tube; the volume of the o-dichlorobenzene solvent is 1-2ml.

[0040] Optionally, the concentration of DB18C6 dissolved in the reaction solution is 0.012-0.024 mol / L.

[0041] Optionally, the molar ratio of DB18C6 to BADT is 1:1-1.3.

[0042] Optionally, the concentration of acetic acid in the reaction solution is 0.28-0.54 mol / L.

[0043] S2. Place the reaction solution in a liquid nitrogen bath for freezing, repeatedly evacuate and purge with nitrogen and seal the tube;

[0044] Optionally, in step S2, the tube is sealed using a flame gun.

[0045] Specifically, in step S2, the vacuuming-nitrogen filling process is repeated 3-5 times, with each vacuuming operation having a pressure of 3-5 Pa.

[0046] S3. Heating reaction, after the reaction is completed and cooled, followed by washing and drying, to obtain the crown ether-based covalent organic framework material BADT-DB18C6-COF;

[0047] Optionally, in step S3, the heating reaction is carried out in an oven at a temperature of 120℃-150℃ for a time of 3-5 days.

[0048] Specifically, in the washing operation described in step S3, anhydrous solvent is used for washing.

[0049] Optionally, the anhydrous solvent is at least one of anhydrous tetrahydrofuran, anhydrous acetone, anhydrous methanol, and anhydrous N,N-dimethylacetamide.

[0050] In one specific embodiment, the mixture was washed three times with anhydrous N,N-dimethylacetamide, three times with anhydrous tetrahydrofuran, and three times with anhydrous methanol.

[0051] Specifically, the drying operation in step S3 is heating vacuum drying, the temperature of which is 100-120℃ and the drying time is 6-12h.

[0052] Specifically, in step S3, the obtained crown ether-based covalent organic framework material

[0053] BADT-DB18C6-COF is a white crystal, and its specific structural formula is shown below:

[0054]

[0055] The following examples further illustrate specific embodiments of the present invention.

[0056] Example 1: Preparation of crown ether-based covalent organic framework material BADT-DB18C6-COF-1

[0057] Add 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT) (0.024 mmol, 10.6 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 (DB18C6) (0.024 mmol, 18.65 mg) to a 10 ml Pyrex tube, add 1 ml of o-dichlorobenzene organic solvent, and sonicate for 10 min. The mixture was thoroughly mixed, and then 0.1 mL of a 6M acetic acid solution was added. The mixture was sonicated for 5 min to ensure uniform dispersion of the catalyst. The Pyrex tube containing the reaction solution was then placed in a liquid nitrogen bath for freezing. The tube was repeatedly evacuated and purged with nitrogen three times each, and then sealed with a flame torch. The tube was then placed in a 120°C oven for crystallization for 3 days. After the reaction was completed, the tube was washed three times with anhydrous N,N-dimethylacetamide, three times with anhydrous tetrahydrofuran, and three times with anhydrous methanol. The tube was then dried under vacuum at 100°C for 8 h to obtain 23.4 mg of white crystals, namely the crown ether covalent organic framework material BADT-DB18C6-COF-1, with a yield of 80%.

[0058] The X-ray diffraction pattern of the white crystal BADT-DB18C6-COF-1 obtained in Example 1 is as follows: Figure 2 As shown, the XRD characteristic diffraction peaks at 6.65°, 8.4°, and 15.05° are very sharp and obvious, indicating that the crown ether-based covalent organic framework material obtained in Example 1 is...

[0059] BADT-DB18C6-COF-1 exhibits long-range ordered crystallization properties.

[0060] Example 2: Preparation of crown ether-based covalent organic framework material BADT-DB18C6-COF-2

[0061] Add 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT) (0.024 mmol, 10.6 mg) and 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 (DB18C6) (DB18C6) (0.024 mmol, 18.65 mg) to a 10 ml Pyrex tube, and add 1.5 ml of [the solution / concentrate / concentrate]. The reaction mixture was prepared by sonicating 10 min with o-dichlorobenzene organic solvent until fully mixed. Then, 0.1 ml of 6M acetic acid solution was added to the catalyst, and sonication continued for 5 min to ensure uniform catalyst dispersion. The Pyrex tube containing the reaction solution was then placed in a liquid nitrogen bath for freezing. The tube was repeatedly evacuated and purged with nitrogen three times each, and sealed with a flame torch. It was then placed in a 120°C oven for crystallization for 3 days. After the reaction, the tube was washed three times with anhydrous N,N-dimethylacetamide, three times with anhydrous tetrahydrofuran, and three times with anhydrous methanol. Finally, it was vacuum dried at 100°C for 8 h to obtain 17.5 mg of white crystals, which is the crown ether-based covalent organic framework material.

[0062] BADT-DB18C6-COF-2, yield 60%.

[0063] Example 3: Preparation of crown ether-based covalent organic framework material BADT-DB18C6-COF-3

[0064] Add 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT) (0.024 mmol, 10.6 mg), and 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 (DB18C6) (0.024 mmol, 18.65 mg) to a 10 ml Pyrex tube, add 1.5 ml of o-dichlorobenzene organic solvent, and ultrafiltration... The mixture was sonicated for 10 minutes to ensure thorough mixing. Then, 0.1 mL of a 6M acetic acid solution was added, and sonication was continued for 5 minutes to ensure uniform dispersion of the catalyst. Subsequently, the Pyrex tube containing the reaction solution was placed in a liquid nitrogen bath for freezing. The tube was repeatedly evacuated and purged with nitrogen three times each, and sealed with a flame torch. It was then placed in a 120°C oven for crystallization for 4 days. After the reaction was completed, the tube was washed three times with anhydrous N,N-dimethylacetamide and three times with anhydrous methanol. Finally, it was vacuum dried at 100°C for 8 hours to obtain 16.1 mg of white crystals, namely the crown ether covalent organic framework material BADT-DB18C6-COF-3, with a yield of 55%.

[0065] Example 4: Preparation of crown ether-based covalent organic framework material BADT-DB18C6-COF-4

[0066] Add 4',5'-bis(4-aminophenyl)-[1,1':2',1”-terphenyl]-4,4”-diamine (BADT) (0.036 mmol, 15.9 mg), and 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 (DB18C6) (0.024 mmol, 18.65 mg) to a 10 ml Pyrex tube, add 1.5 ml of o-dichlorobenzene organic solvent, and ultrafiltration... The mixture was sonicated for 10 minutes to ensure thorough mixing. Then, 0.1 ml of a 6M acetic acid solution was added, and sonication was continued for 5 minutes to ensure uniform dispersion of the catalyst. Subsequently, the Pyrex tube containing the reaction solution was placed in a liquid nitrogen bath for freezing. The tube was repeatedly evacuated and purged with nitrogen three times each, and sealed with a flame torch. It was then placed in a 150°C oven for crystallization for 4 days. After the reaction was completed, the tube was washed three times with anhydrous N,N-dimethylacetamide and three times with anhydrous methanol. Finally, it was vacuum dried at 100°C for 8 hours to obtain 14.6 mg of white crystals, namely the crown ether covalent organic framework material BADT-DB18C6-COF-4, with a yield of 50%.

[0067] Application Example 1: Adsorption of uranyl ions by the crown ether-based covalent organic framework material BADT-DB18C6-COF

[0068] Before the experiment, 1 mg of each of the BADT-DB18C6-COF-1 to BADT-DB18C6-COF-4 samples obtained in Examples 1-4 above was weighed and added to 15 ml centrifuge tubes respectively.

[0069] Next, a 12 ml solution of uranyl ions with a concentration of approximately 200 mg / L was prepared. The pH of the solution was then adjusted to 3, and the precise concentration C0 of the uranium solution before adsorption was measured using X-ray fluorescence spectrometry (XRF). The solution was then divided into four equal portions of 3 ml each and added sequentially to centrifuge tubes (15 ml each) containing 1 mg of adsorbent. The tubes were sealed and placed in a constant-temperature water bath shaker. The adsorption conditions were set as follows: temperature 25°C, shaking time 5 hours. After adsorption was complete, the centrifuge tubes were removed, and the supernatant was collected using a syringe with a filter tip. The concentration C0 was measured using XRF. i The adsorption capacity q is calculated according to formula (1). e As shown in Table 1.

[0070] q e =(C0-C i )×V / m (1)

[0071] Table 1. Uranium adsorption capacity of BADT-DB18C6-COF-1 to BADT-DB18C6-COF-4

[0072] Material Name Uranium adsorption capacity (mg / g) BADT-DB18C6-COF-1 35.8 BADT-DB18C6-COF-2 26.6 BADT-DB18C6-COF-3 20.6 BADT-DB18C6-COF-4 15.9

[0073] In this application example, the nitric acid concentration in the prepared uranyl ion solution was adjusted to 0.3M and 3M, respectively, while other conditions remained unchanged. Using BADT-DB18C6-COF-1 as the adsorbent, the uranium adsorption capacity was as follows: Figure 3 As shown, the nitric acid concentration ranges from 10... -3 As M gradually increases from 0.3M to 3M, the amount of uranium adsorbed first decreases and then increases.

[0074] Application Example 2: Adsorption of Thorium Ions by Crown Ether-Based Covalent Organic Framework Material BADT-DB18C6-COF

[0075] Before the experiment, the BADT-DB18C6-COF-1 obtained in Examples 1-4 above were used...

[0076] Weigh 1 mg of each BADT-DB18C6-COF-4 sample and add them to 15 ml centrifuge tubes.

[0077] Next, a 12 ml thorium ion solution with a concentration of approximately 200 mg / L was prepared. The pH of the solution was then adjusted to 3, and the precise concentration C0 of the thorium solution before adsorption was measured using X-ray fluorescence spectrometry (XRF). The solution was then divided into four equal portions of 3 ml each and added sequentially to centrifuge tubes (15 ml each) containing 1 mg of adsorbent. The tubes were sealed and placed in a constant-temperature water bath shaker. The adsorption conditions were set as follows: temperature 25°C, shaking time 5 hours. After adsorption was complete, the centrifuge tubes were removed, and the supernatant was collected using a syringe with a filter tip. The concentration C0 was measured using XRF. i The adsorption capacity was calculated according to formula (1), as shown in Table 2.

[0078] Table 2 Thorium adsorption capacity of BADT-DB18C6-COF-1 to BADT-DB18C6-COF-4

[0079] Material Name Thorium adsorption capacity (mg / g) BADT-DB18C6-COF-1 63.7 BADT-DB18C6-COF-2 50.2 BADT-DB18C6-COF-3 42.9 BADT-DB18C6-COF-4 30.6

[0080] In this application example, the nitric acid concentration in the prepared thorium ion solution was adjusted to 0.3M and 3M, while other conditions remained unchanged. Using BADT-DB18C6-COF-1 as the adsorbent, the thorium adsorption capacity was as follows: Figure 4 As shown, the nitric acid concentration ranges from 10... -3 As M gradually increases from 0.3M to 3M, the thorium adsorption capacity shows a trend of first decreasing and then increasing.

[0081] Application Example 3: Adsorption of americium ions by the crown ether-based covalent organic framework material BADT-DB18C6-COF

[0082] Before the experiment, the BADT-DB18C6-COF-1 obtained in Examples 1-4 above were used...

[0083] Weigh 1 mg of each BADT-DB18C6-COF-4 sample and add them to 15 ml centrifuge tubes.

[0084] Next, a 12 ml americium ion solution with a concentration of approximately 200 mg / L was prepared. The pH of the solution was then adjusted to 3, and the precise concentration C0 of the americium solution before adsorption was measured using X-ray fluorescence spectrometry (XRF). The solution was then divided into four equal portions of 3 ml each and added sequentially to centrifuge tubes (15 ml each) containing 1 mg of adsorbent. The tubes were sealed and placed in a constant-temperature water bath shaker. The adsorption conditions were set as follows: temperature 25°C, shaking time 5 hours. After adsorption was complete, the centrifuge tubes were removed, and the supernatant was collected using a syringe with a filter tip. The concentration C0 was measured using XRF. i The adsorption capacity was calculated according to formula (1), as shown in Table 3.

[0085] Table 3. Thorium adsorption capacity of americium adsorbed by BADT-DB18C6-COF-1 to BADT-DB18C6-COF-4

[0086] Material Name Americium adsorption capacity (μg / g) BADT-DB18C6-COF-1 873.8 BADT-DB18C6-COF-2 700.9 BADT-DB18C6-COF-3 500.9 BADT-DB18C6-COF-4 400.8

[0087] The methods described in this invention are not limited to the specific embodiments described above. The embodiments are merely illustrative examples of this invention, and this invention can also be implemented in other specific ways or forms without departing from the spirit or essential characteristics of this invention. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of this invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of this invention.

Claims

1. A crown ether-based covalent organic framework material, characterized in that, The crown ether group covalent organic framework material is BADT-DB18C6-COF, which is condensed from a crown ether monomer and an amino monomer, wherein the crown ether monomer is 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl) tetrakisbenzaldehyde; and the amino monomer is 4',5'-bis(4-aminophenyl)-[1,1':2',1''-terphenyl]-4,4''-diamine. The BADT-DB18C6-COF has the following structural formula:

2. A method of preparing the crown ether-based covalent organic framework material of claim 1, wherein, The method comprises the following steps: S1, preparing a reaction solution: dissolving 4',5'-bis(4-aminophenyl)-[1,1':2',1''-terphenyl]-4,4''-diamine and 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl) tetrakisbenzaldehyde in o-dichlorobenzene solvent, then adding acetic acid solution and uniformly dispersing to obtain a reaction solution; S2, freezing the reaction solution in a liquid nitrogen bath, repeatedly vacuumizing-nitrogen filling and sealing the tube; S3, heating the reaction, after the reaction is completed and cooled, washing and drying treatment are performed to obtain the crown ether group covalent organic framework material BADT-DB18C6-COF.

3. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, Step S1 comprises the following specific steps: adding 4',5'-bis(4-aminophenyl)-[1,1':2',1''-terphenyl]-4,4''-diamine and 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl) tetrakisbenzaldehyde into o-dichlorobenzene solvent, ultrasonic treatment until dissolution; then adding acetic acid solution, continuing ultrasonic treatment until the acetic acid is uniformly dispersed to obtain a reaction solution.

4. The method for preparing a crown ether-based covalent organic framework material according to claim 3, characterized in that, In step S1, 4',5'-bis(4-aminophenyl)-[1,1':2',1''-terphenyl]-4,4''-diamine and 4,4',4'',4'''-(6,7,9,10,17,18,20,21-octahydrodibenzo[B,K][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl) tetrakisbenzaldehyde are added into o-dichlorobenzene solvent, ultrasonic treatment is performed for 10-20 min until dissolution; then acetic acid solution is added, ultrasonic treatment is continued for 5-10 min until the acetic acid is uniformly dispersed to obtain a reaction solution.

5. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S1, the reaction solution is prepared in a 10 ml pyrex tube. The volume of the o-dichlorobenzene solvent is 1-2 ml.

6. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S1, the volume of the acetic acid solution is 0.1-0.2 ml. In step S1, the volume of the acetic acid solution is 0.1-0.2 ml. The concentration of [B,K][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl)tetraphenylaldehyde in the reaction solution is 0.012-0.024 mol / L.

7. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S1, the concentration of acetic acid in the reaction solution is 0.28-0.54 mol / L. In step S2, the molar ratio of [B,K][1,4,7,10,13,16]hexaoxacyclooctadecine-2,3,13,14-tetrayl)tetraphenylaldehyde to 4',5'-bis(4-aminophenyl)-[1,1':2',1''-terphenyl]-4,4''-diamine is 1:1-1.

3.

8. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S1, the concentration of acetic acid in the reaction solution is 0.28-0.54 mol / L.

9. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S2, the tube is sealed with a flame spray gun.

10. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S2, the vacuum-nitrogen filling is a 3-5 cycle operation, and the pressure of each vacuum extraction is 3-5 Pa.

11. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S3, the heating reaction is carried out in an oven, the reaction temperature is 120-150 DEG C, and the reaction time is 3-5 days.

12. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, In step S3, the washing operation is carried out with anhydrous solvent.

13. The method for preparing a crown ether-based covalent organic framework material according to claim 12, characterized in that, The anhydrous solvent is at least one of anhydrous tetrahydrofuran, anhydrous acetone, anhydrous methanol, and anhydrous N,N-dimethylacetamide.

14. The method for preparing a crown ether-based covalent organic framework material according to claim 2, characterized in that, The drying operation in step S3 is heated vacuum drying, the temperature of the heated vacuum drying is 100-120 DEG C, and the drying time is 6-12 h.

15. Use of the crown ether-based covalent organic framework material of claim 1, wherein, The BADT-DB18C6-COF material is used for adsorbing and recovering radionuclides U-238, Th-232 and Am-243 from solution.

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