Silver ion functionalized covalent organic framework material as well as preparation method and application thereof

Abstract

The invention discloses a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption and a preparation method of the silver ion functionalized covalent organic framework material. The preparation method comprises the following steps: dissolving 2, 5 '-diamino-2, 2'-dipyridyl and trialdehyde phloroglucinol serving as reaction monomers in a solvent of o-dichlorobenzene and N, N-dimethylacetamide, and preparing a covalent organic framework material TpBpy containing a dipyridyl group by using acetic acid as a catalyst; and S2, by taking a bipyridine group as a silver ion chelation site, blending the covalent organic framework material TpBpy with a silver nitrate solution to prepare the silver ion loaded covalent organic framework material TpBpy-Ag. The preparation method of the silver ion functionalized covalent organic framework material provided by the invention is simple, convenient, universal and high in controllability, and the prepared silver ion functionalized covalent organic framework material shows excellent iodine adsorption capacity when being used for adsorbing and separating iodine.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of functional polymer materials, and in particular relates to a silver ion functionalized covalent organic framework material and a preparation method and application thereof. Background Art

[0002] As a safe, efficient, new type of high-quality clean energy, nuclear energy has the advantages of not emitting greenhouse gases and operating stably and reliably. The development of nuclear energy will inevitably produce 85 Kr, 133 Xe, 129 I. 131 I. 3 H and 14 C and other radioactive gases with a long half-life. Among them, radioactive iodine 131 I and 129 The release of I will cause radioactive pollution to the environment and participate in the metabolic process of iodine in the human body, causing serious harm to human health and the environment. At present, solid adsorption technology is mainly used to treat radioactive gaseous iodine at home and abroad. Nuclear power plants generally use nuclear-grade impregnated activated carbon as a material for radioactive iodine capture. However, its capture performance will be significantly reduced due to the long-term desorption and poisoning of the impregnant. Metal organic frameworks (MOFs) are a new type of adsorbent that has emerged in recent years. Their adsorption capacity for radioactive iodine is significantly affected by airflow conditions and radiation, and cannot achieve the expected separation effect.

[0003] Covalent organic frameworks (COFs) are a new type of crystalline porous materials with a highly ordered structure, which are composed of organic building units connected by strong covalent bonds. They have high specific surface area, regularly distributed pore structure, adjustable structural chemical properties, and excellent chemical and thermal stability. They show excellent application potential in the process of radioactive iodine capture. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, according to the first aspect of the present invention, a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption is provided, and its structure is shown in formula (I):

[0005]

[0006] Among them, the X-ray diffraction spectrum of the compound represented by formula (I) shows diffraction peaks at diffraction angles (2θ): 2θ=3.80°±0.2°, 2θ=5.90°±0.2°, and 2θ=26.84°±0.2°.

[0007] According to a second aspect of the present invention, there is provided a method for preparing a silver ion functionalized covalent organic framework material for radioactive isotope iodine adsorption, comprising: step S1, selecting 5,5'-diamino-2,2'-bipyridine and trialdehyde pyrogallol as reaction monomers, dissolving them in o-dichlorobenzene and N,N-dimethylacetamide solvents, using acetic acid as a catalyst, and preparing a covalent organic framework material TpBpy containing a bipyridine group; step S2, using the bipyridine group as a silver ion chelating site, blending the covalent organic framework material TpBpy with a silver nitrate solution, and preparing a silver ion-loaded covalent organic framework material TpBpy-Ag.

[0008] Preferably, the step S1 comprises: step S11, dissolving 5,5'-diamino-2,2'-bipyridine in o-dichlorobenzene to obtain a first mixed solution, dissolving trialdehyde phloroglucinol in N,N-dimethylacetamide to obtain a second mixed solution, and blending an acetic acid aqueous solution with the first mixed solution and the second mixed solution to obtain a mixed solution; step S12, subjecting the mixed solution obtained in the step S11 to ultrasonic treatment and then stirring it to obtain a stirred solution; step S13, transferring the stirred solution obtained in the step S12 to a pressure-resistant reaction tube, placing the reaction tube in a vacuum environment, and placing the vacuum reaction tube in an oven for reaction to obtain a reacted solution; step S14, filtering the reacted solution obtained in the step S13 to separate a solid product, and then washing it with N,N-dimethylacetamide and deionized water for multiple times in sequence to obtain a washed reaction product; step S15, subjecting the washed reaction product obtained in the step S14 to solvent exchange with acetone and then drying it in a vacuum oven.

[0009] Preferably, step S13 comprises: step (1), placing the reaction tube in liquid nitrogen and freezing it until the solution in the reaction tube changes from liquid to solid; step (2), connecting the reaction tube frozen in step (1) to a vacuum pump, and turning on the vacuum pump to evacuate the reaction tube; step (3), placing the vacuumed reaction tube in step (2) in deionized water at room temperature and letting it stand until the solution in the reaction tube changes from solid to liquid; step (4), repeating steps (1) to (3) multiple times.

[0010] Preferably, the step S2 comprises: step S21, preparing a silver nitrate solution, mixing the covalent organic framework material TpBpy obtained in the step S1 with the silver nitrate solution in a nitrogen-filled flask, and mechanically stirring at room temperature and in the dark to obtain a stirred solution; step S22, centrifuging the stirred solution obtained in the step S21 to obtain a separated solid, and washing it with acetone for multiple times; step S23, soaking the separated solid obtained in the step S22 in a dimethyl sulfoxide solution, filtering, washing it with acetone for multiple times, and placing it in an oven for vacuum drying to obtain a silver ion functionalized covalent organic framework material TpBpy-Ag.

[0011] Preferably, the concentration of the silver nitrate solution is 0.1 mol / L; the molar ratio of the silver nitrate to the covalent organic framework material TpBpy is 1:25.

[0012] Preferably, the molar ratio of the 5,5'-diamino-2,2'-bipyridine, the trialdehyde phloroglucinol, the o-dichlorobenzene, the N,N-dimethylacetamide, and the acetic acid is 1:1.5:160:10:12.

[0013] Preferably, the mixed solution obtained in step S11 is subjected to ultrasonic treatment for 10 minutes to 30 minutes.

[0014] According to a third aspect of the present invention, there is provided application of the above-mentioned silver ion functionalized covalent organic framework material in the adsorption of radioactive nuclide iodine.

[0015] According to a fourth aspect of the present invention, there is provided the use of the silver ion functionalized covalent organic framework material obtained by the preparation method of the silver ion functionalized covalent organic framework material in the adsorption of radioactive nuclide iodine.

[0016] Any of the above technical solutions of the present invention can achieve at least one of the following beneficial effects:

[0017] The silver ion functionalized TpBpy material prepared by the present invention has abundant silver ion sites and imine groups with strong adsorption effect on radioactive iodine in its pores, thereby achieving a significant improvement in adsorption rate and adsorption capacity.

[0018] The method for preparing the silver ion functionalized covalent organic framework material provided by the present invention is simple, universal and highly controllable. The prepared silver ion functionalized covalent organic framework material is used for the adsorption and separation of iodine and exhibits excellent iodine adsorption capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural diagram of the silver ion functionalized covalent organic framework material provided by the present invention.

[0020] Figure 2 Schematic diagram of the synthesis route of the silver ion functionalized covalent organic framework material according to an embodiment of the present invention.

[0021] Figure 3 The invention discloses an X-ray diffraction spectrum of a silver ion functionalized covalent organic framework material. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. The described embodiments should not be regarded as limiting the present application, and all other implementation schemes obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0023] Unless otherwise defined, all terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0024] According to a first aspect of the present invention, a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption is provided. The structure of the silver ion functionalized covalent organic framework material provided by the present invention is described below.

[0025] The present invention provides a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption, and its structure is shown in formula (I):

[0026]

[0027] Among them, the compound of formula (I) has an X-ray diffraction spectrum showing diffraction peaks at diffraction angles (2θ): 2θ=3.80°±0.2°, 2θ=5.90°±0.2°, and 2θ=26.84°±0.2°, corresponding to the (100), (200), and (001) crystal planes of the crystal, respectively. TpBpy-Ag reduces the regularity of the pores due to the silver loading in the pores, resulting in a decrease in the intensity of the corresponding diffraction peaks.

[0028] According to a second aspect of the present invention, a method for preparing a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption is provided. The preparation method provided by the present invention is described in detail below.

[0029] The method for preparing a silver ion functionalized covalent organic framework material provided by the present invention comprises: step S1, a step of preparing a covalent organic framework TpBpy. Step S2, a step of loading silver ions. The two steps are described in detail below.

[0030] Step S1, the step of preparing the covalent organic framework TpBpy. 5,5'-diamino-2,2'-bipyridine (Bpy) and trialdehyde phloroglucinol (Tp) are selected as reaction monomers, dissolved in o-dichlorobenzene (o-DCB) and N,N-dimethylacetamide (DMAc) solvents, and acetic acid is used as a catalyst to prepare the covalent organic framework material TpBpy containing bipyridine groups under solvent thermal reaction conditions. Step S1 specifically includes the following steps:

[0031] Step S11, dissolving Bpy in o-DCB to obtain a first mixed solution, dissolving Tp in DMAc to obtain a second mixed solution, and blending the acetic acid aqueous solution with the first mixed solution and the second mixed solution to obtain a mixed solution. Preferably, the molar ratio of Bpy, Tp, o-DCB, DMAc, and acetic acid is 1:1.5:160:10:12.

[0032] Step S12, after ultrasonic treatment, the mixed solution obtained in step S11 is stirred to be fully mixed and uniform, to obtain a stirred solution. Preferably, the mixed solution obtained in step S11 is subjected to ultrasonic treatment for 10 minutes to 30 minutes. Preferably, in step S11, mechanical stirring is performed at 30° C. to 50° C. and 500 rpm to 800 rpm for 1 hour to 3 hours. By subjecting the above-mentioned ultrasonic treatment and stirring based on the above-mentioned stirring conditions, the solution can be fully mixed and uniform, which is more conducive to improving the crystallinity of the synthesized product.

[0033] Step S13, transferring the stirred solution obtained in step S12 into a pressure-resistant reaction tube, then placing the reaction tube in a vacuum environment, and placing the vacuum reaction tube in an oven for reaction to obtain a reacted solution. The step of placing the reaction tube in a vacuum environment further includes the following steps:

[0034] (1) Liquid nitrogen freezing: The vacuum reaction tube is placed in liquid nitrogen for freezing until the solution in the reaction tube changes from liquid to solid. Preferably, the vacuum reaction tube is placed in liquid nitrogen for 10 to 15 minutes.

[0035] (2) Vacuuming: Connect the vacuum reaction tube frozen in the above (1) to a vacuum pump, start the vacuum pump to evacuate the reaction tube so that the reaction tube is in a high vacuum environment, then close the valve connecting the reaction tube and the vacuum pump, and turn off the vacuum pump. Preferably, the vacuum pump is continuously evacuated for 1 minute to 3 minutes.

[0036] (3) Thawing: Place the vacuum reaction tube in (2) above in deionized water at room temperature and let it stand until the solution in the reaction tube changes from solid to liquid. Preferably, let it stand in deionized water at room temperature for 5 to 10 minutes.

[0037] (4) Repeat the above steps (1) to (3) for multiple times. Preferably, the above steps (1) to (3) are repeated three times. By repeating the above steps, a high vacuum environment can be ensured in the reaction tube, thereby improving the yield of the reactants.

[0038] Step S14, filtering the reacted solution obtained in step S13 to separate the solid product, and then washing it with DMAc and deionized water for multiple times in sequence to obtain a washed reaction product. Preferably, washing with DMAc and deionized water for three to five times in sequence. Since the residual reaction solvent will block the pores and reduce the adsorption performance of the reaction product, the above-mentioned multiple washings can remove the residual reaction solvent in the reaction product and reduce the blockage of the pores.

[0039] Step S15, the reaction product after washing obtained in step S14 is subjected to solvent exchange with acetone and then placed in a vacuum oven for drying to further remove the reaction solvent remaining in the reaction product. Preferably, the time for the above-mentioned solvent exchange is 2 to 3 days. Preferably, the drying temperature of the vacuum oven is 120° C. to 150° C. Preferably, the drying time of the vacuum oven is 12 hours to 24 hours.

[0040] After the above steps, the covalent organic framework material TpBpy containing bipyridine groups can be obtained.

[0041] Step S2, silver ion loading step. Using the bipyridine group as the silver ion chelating site, the covalent organic framework material TpBpy is mixed with a silver nitrate solution to prepare a silver ion functionalized covalent organic framework material TpBpy-Ag. Step S2 specifically includes the following steps:

[0042] Step S21, prepare silver nitrate (AgNO 3 ) solution, the covalent organic framework material TpBpy obtained in step S1 and the prepared AgNO 3 The solutions are mixed in a flask filled with nitrogen and mechanically stirred at room temperature in the dark to obtain a stirred solution. Preferably, AgNO 3 The concentration of the solution is 0.1 mol / L. Preferably, the AgNO 3 The molar ratio of Ag to TpBpy is 1:25. Preferably, stirring is continued for 12 to 14 hours. After continuous stirring for a long time, Ag ions can be fully contacted with TpBpy, allowing as many Ag ions as possible to enter the pores of TpBpy, thereby achieving a higher Ag ion loading.

[0043] Step S22, centrifugally separate the stirred solution obtained in step S21 to obtain a separated solid, and wash it several times with sufficient acetone to remove excess AgNO 3Preferably, washing with acetone is performed three to five times.

[0044] Step S23, soaking the separated solid obtained in step S22 in a dimethyl sulfoxide (DMSO) solution, filtering, washing with acetone for multiple times, and placing in an oven for vacuum drying to obtain a silver ion functionalized covalent organic framework material TpBpy-Ag. Preferably, washing with acetone three to five times. Preferably, the concentration of the DMSO solution is 5 mg / mL to 10 mg / mL. Preferably, the temperature of the above-mentioned oven drying is 60°C to 90°C. Preferably, the above-mentioned oven drying time is 12 hours to 24 hours.

[0045] After the above steps, the silver ion functionalized covalent organic framework material TpBpy-Ag can be obtained.

[0046] According to a third aspect of the present invention, there is provided application of the above-mentioned silver ion functionalized covalent organic framework material in the adsorption of radioactive nuclide iodine.

[0047] According to a fourth aspect of the present invention, there is provided the use of the silver ion functionalized covalent organic framework material obtained by the preparation method of the silver ion functionalized covalent organic framework material in the adsorption of radioactive nuclide iodine.

[0048] In order to enable those skilled in the art to more clearly understand the technical solution of the present disclosure, the technical solution of the present disclosure will be described in detail below in conjunction with specific embodiments.

[0049] Example

[0050] The present application is illustrated below by way of examples, but this should not be construed as limiting the scope of the subject matter of the present application to the following examples. All technologies implemented based on the above content of the present application belong to the scope of the present application. The compounds or reagents used in the following examples can be purchased from commercial sources or prepared by conventional methods known to those skilled in the art; the experimental instruments used can be purchased from commercial sources.

[0051] (1) Preparation of covalent organic framework TpBpy:

[0052] Weigh 0.42g of Bpy and 0.32g of Tp and dissolve them in 20mL Lo-DCB and 5mL DMAc respectively, take 2mL of the prepared 6mol / L acetic acid aqueous solution and mix with the above two solutions, and ultrasonically treat for 10min. Mechanically stir for 1 hour at 30℃ and 500rpm. The stirred solution is transferred to a pressure-resistant vacuum reaction tube, and after three cycles of liquid nitrogen freezing-vacuuming-thawing, the reaction tube is ensured to be in a vacuum environment, and placed in a 120℃ oven for reaction for 3 days. After filtering, the obtained reaction solution is washed three times with DMAc (30mL) and deionized water (30mL), and then exchanged with acetone solvent for 2 days and placed in a 120℃ vacuum oven for 12h to obtain a covalent organic framework material TpBpy containing a bipyridine group.

[0053] (2) Preparation of silver ion functionalized covalent organic framework material TpBpy-Ag:

[0054] 200 mg of TpBpy was mixed with 500 mL of 0.1 mol / L AgNO 3 The solutions were mixed in a flask, which was filled with nitrogen and mechanically stirred for 12 h at room temperature in the dark. The stirred solution was centrifuged to separate the solids and washed with sufficient acetone to remove excess AgNO 3 To further improve the crystallinity of the material, the separated solid was immersed in a 5 mg / mL DMSO solution for 48 h, filtered, washed three times with acetone (30 mL), placed in an oven, and vacuum dried at 60 °C for 12 h to obtain the silver ion functionalized covalent organic framework material TpBpy-Ag.

[0055] Iodine adsorption performance test

[0056] The iodine adsorption performance of the silver ion functionalized covalent organic framework material TpBpy-Ag obtained by the preparation method provided by the present invention is tested as follows:

[0057] Three 5 mL glass vials containing TpBpy-Ag, elemental iodine and blank reference samples were placed in a 100 mL wide-mouth bottle and the wide-mouth bottle was sealed and then placed in an oven at 75°C. The small glass bottle containing the adsorbent was weighed and placed back into the wide-mouth bottle at regular intervals until its weight reached a stable value. The iodine adsorption capacity of the adsorbent was measured by the weight change of the adsorbent. The iodine adsorption capacity of the material was calculated according to formula (1):

[0058]

[0059] where q t It represents the iodine adsorption capacity of the material within time t, in g / g -1 ;m trepresents the weight of the vial containing the adsorbent at time t, in g; m 1 represents the initial weight of the vial containing the adsorbent, in g; m 0 Indicates the weight of the vial without adsorbent, in g; M t Indicates the weight of the reference sample at time t, in g; M 0 Indicates the initial weight of the reference sample in g.

[0060] Table 1 shows the comparison results of the adsorption performance of the conventional iodine adsorption material and the iodine adsorption performance of the silver ion functionalized covalent organic framework material TpBpy-Ag prepared by the preparation method provided by the present invention. Here, the conventional iodine adsorption material uses TEDA (1,4-diazabicyclo[2.2.2]octane) impregnated activated carbon.

[0061] Table 1 Comparison of iodine adsorption test results of TpBpy and TpBpy-Ag obtained by the present invention and impregnated activated carbon

[0062]

[0063] It can be seen from the above table that the adsorption of radioactive iodine by conventional TEDA-impregnated activated carbon is achieved, but it is difficult to achieve a high adsorption rate and a large adsorption capacity due to the limitation of the impregnant loading (less than 5%). The silver ion-functionalized TpBpy material prepared by the present invention contains abundant silver ion sites and imine groups that have a strong adsorption effect on radioactive iodine in its pores, achieving a significant improvement in the adsorption rate and adsorption capacity.

[0064] The method for preparing the silver ion functionalized covalent organic framework material provided by the present invention is simple, universal and highly controllable. The prepared silver ion functionalized covalent organic framework material is used for the adsorption and separation of iodine and exhibits excellent iodine adsorption capacity.

Claims

1. A covalent organic framework material functionalized with silver ions for radionuclide iodine adsorption, characterized in that: The structure is shown in formula (I): Among them, the X-ray diffraction spectrum of the compound represented by formula (I) shows diffraction peaks at diffraction angles (2θ): 2θ=3.80°±0.2°, 2θ=5.90°±0.2°, and 2θ=26.84°±0.2°.

2. A method for preparing a covalent organic framework material functionalized with silver ions for radionuclide iodine adsorption, characterized in that: include: Step S1, selecting 5,5'-diamino-2,2'-bipyridine and trialdehyde phloroglucinol as reaction monomers, dissolving them in o-dichlorobenzene and N,N-dimethylacetamide solvents, using acetic acid as a catalyst, to prepare a covalent organic framework material TpBpy containing a bipyridine group; Step S2, using the bipyridine group as the silver ion chelating site, mixing the covalent organic framework material TpBpy with a silver nitrate solution to prepare the silver ion loaded covalent organic framework material TpBpy-Ag.

3. The method for preparing a covalent organic framework material functionalized with silver ions for radionuclide iodine adsorption according to claim 2, characterized in that: The step S1 comprises: Step S11, dissolving 5,5'-diamino-2,2'-bipyridine in o-dichlorobenzene to obtain a first mixed solution, dissolving trialdehyde phloroglucinol in N,N-dimethylacetamide to obtain a second mixed solution, and blending acetic acid aqueous solution with the first mixed solution and the second mixed solution to obtain a mixed solution; Step S12, subjecting the mixed solution obtained in step S11 to ultrasonic treatment and then stirring the mixed solution to obtain a stirred solution; Step S13, transferring the stirred solution obtained in step S12 into a pressure-resistant reaction tube, placing the reaction tube in a vacuum environment, and placing the vacuum reaction tube in an oven for reaction to obtain a reacted solution; Step S14, filtering the reacted solution obtained in step S13 to separate a solid product, and then washing it with N,N-dimethylacetamide and deionized water for multiple times to obtain a washed reaction product; Step S15, using acetone to perform solvent exchange on the cleaned reaction product obtained in step S14 and then putting it into a vacuum oven for drying.

4. The method for preparing a covalent organic framework material functionalized with silver ions for radionuclide iodine adsorption according to claim 3, characterized in that: The step S13 comprises: Step (1), placing the reaction tube in liquid nitrogen to freeze until the solution in the reaction tube changes from liquid to solid; Step (2), connecting the reaction tube frozen in step (1) to a vacuum pump, and turning on the vacuum pump to evacuate the reaction tube; Step (3), placing the vacuum reaction tube in step (2) in deionized water at room temperature and leaving it to stand until the solution in the reaction tube changes from solid to liquid; Step (4), repeating steps (1) to (3) multiple times.

5. The method for preparing a covalent organic framework material functionalized with silver ions for radionuclide iodine adsorption according to claim 2, characterized in that: The step S2 comprises: Step S21, preparing a silver nitrate solution, mixing the covalent organic framework material TpBpy obtained in step S1 with the silver nitrate solution in a flask filled with nitrogen, and mechanically stirring at room temperature in the dark to obtain a stirred solution; Step S22, centrifugally separating the stirred solution obtained in step S21 to obtain a separated solid, and washing the solid with acetone for multiple times; Step S23, immersing the separated solid obtained in step S22 in a dimethyl sulfoxide solution, filtering, washing with acetone for multiple times, and placing in an oven for vacuum drying to obtain a silver ion functionalized covalent organic framework material TpBpy-Ag.

6. The method for preparing a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption according to claim 5, characterized in that: The concentration of the silver nitrate solution is 0.1 mol / L; The molar ratio of the silver nitrate to the covalent organic framework material TpBpy is 1:

25.

7. The method for preparing a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption according to any one of claims 2 to 6, characterized in that: The molar ratio of the 5,5'-diamino-2,2'-bipyridine, the trialdehyde pyroglutinol, the o-dichlorobenzene, the N,N-dimethylacetamide and the acetic acid is 1:1.5:160:10:

12.

8. The method for preparing a silver ion functionalized covalent organic framework material for radionuclide iodine adsorption according to any one of claims 2 to 6, characterized in that: The mixed solution obtained in step S11 is subjected to ultrasonic treatment for 10 to 30 minutes.

9. Use of the silver ion functionalized covalent organic framework material according to claim 1 in the adsorption of radionuclide iodine.

10. Use of the silver ion functionalized covalent organic framework material obtained by the method for preparing the silver ion functionalized covalent organic framework material according to any one of claims 2 to 7 in the adsorption of radioactive nuclide iodine.

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