A preparation method for amidoximated COFs material with dual functions of adsorption and detection of uranyl

Abstract

The invention belongs to the field of chemistry and environmental technology, and relates to a preparation method of amidoximated COFs material with adsorption and detection of uranyl bifunctional. The present invention uses 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde as raw materials, and obtains cyanated COFs material after reaction; The cyanated COFs material is subjected to amidoximation modification to obtain amidoximated COFs material with adsorption and detection of uranyl bifunctional. The amidoximated COFs material with adsorption and detection of uranyl bifunctional prepared by post-modification has high adsorption selectivity and faster adsorption kinetics (5.11mg / g / min) for uranyl, has unique and excellent adsorption performance for hexavalent uranium, is easy to recover and recycle, and is environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of chemistry and environmental technology, and in particular to a method for preparing an amidoximated COFs material with dual functions of adsorbing and detecting uranyl. Background Art

[0002] Uranium is a key element in the nuclear industry. Extracting uranium from the environment is beneficial to the sustainable development of the energy industry. However, uranium is also a global environmental pollutant with combined radioactive and chemical toxicity. Under natural conditions, the primary valence state of uranium is U(VI), which is characterized by high mobility, high radioactivity, and high toxicity. Its radiotoxicity is particularly significant, as its extremely long decay process is accompanied by the generation of gamma radiation. Radiotoxicity and chemotherapy can lead to irreversible human health and survival risks. However, the harsh environment and abundant interfering ions present challenges for uranium detection and recovery.

[0003] Covalent organic framework materials are a class of crystalline porous materials with a periodic structure that can achieve a precise combination of organic structural units. COFs have shown great potential in the adsorption and separation of metal ions due to their structural diversity, regular pore structure and large specific surface area. COFs modified with amidoxime groups are star materials for uranium adsorption due to their high selectivity for uranium. However, the traditional solvothermal synthesis method requires harsh conditions, such as high temperature and long reaction time. Moreover, most of the COFs materials modified with amidoxime are used for the single adsorption of uranium, and the development of COFs materials with dual functions of adsorption and detection still has certain challenges. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing an amidoximated COFs material with dual functions of adsorbing and detecting uranyl, so as to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing amidoximated COFs material with dual functions of adsorbing and detecting uranyl, comprising the following steps:

[0007] Using 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde as raw materials, cyanated COFs materials were obtained after reaction;

[0008] The cyanated COFs material is subjected to amidoximation modification to obtain the amidoximated COFs material having the dual functions of adsorbing and detecting uranyl.

[0009] Furthermore, the preparation steps of the cyanated COFs material include:

[0010] Ultrasonic mixing of 3,4-diaminobenzonitrile, 2-hydroxy-1,3,5-benzenetricarboxaldehyde and acetonitrile to obtain a mixed solution;

[0011] Add acetic acid to the mixed solution and stir, then allow to react at room temperature. After the reaction is complete, centrifuge, wash, and vacuum dry to obtain a cyanated COFs material.

[0012] Preferably, the molar ratio of the 3,4-diaminobenzonitrile to 2-hydroxy-1,3,5-benzenetricarboxaldehyde is 3:1-5.

[0013] Preferably, the concentration of the acetic acid is 12M.

[0014] Preferably, the volume ratio of the acetic acid to the mixed solution is 7:50.

[0015] Preferably, the volume ratio of the sum of the molar amounts of 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde to acetonitrile is 4-8 mmol:250 mL.

[0016] Preferably, the ultrasonic mixing time is 5 to 10 minutes.

[0017] Preferably, the stirring time is 10 minutes.

[0018] Preferably, the static reaction time is 3 to 5 days.

[0019] Preferably, the washing is performed at least once using ethanol.

[0020] Furthermore, the amidoximation modification step includes:

[0021] The cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate are mixed with ethanol and water, and heated and stirred under nitrogen protection for reaction. After the reaction is completed, the solid product is collected by centrifugation, washed and vacuum dried to obtain the amidoximated COFs material with the dual functions of adsorbing and detecting uranyl.

[0022] Preferably, the mass ratio of the cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate is 1:1-10:1-10.

[0023] Preferably, the ratio of the sum of the masses of the cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate to the sum of the volumes of ethanol and water is 3-21 g:300 mL.

[0024] Preferably, the volume ratio of ethanol to water is 9:1.

[0025] Preferably, the heating temperature is 70-90°C.

[0026] Preferably, the stirring time is 6 to 10 hours.

[0027] Preferably, the washing is performed by alternating washing with water and ethanol at least once.

[0028] The second technical solution of the present invention is to provide an amidoximated COFs material prepared by the above preparation method.

[0029] The third technical solution of the present invention is to provide an application of the amidoximated COFs material as an adsorption material for adsorbing uranium in water.

[0030] Furthermore, the application method steps are: adding the amidoximated COFs material as an adsorption material into the water body to adsorb and enrich hexavalent uranium, the adsorption time is 5-1440 minutes, the addition amount is 10-100 mg / L, the pH of the water body is 2-12, and the adsorption temperature is 25-45°C.

[0031] The fourth technical solution of the present invention is to provide an application of the above-mentioned amidoximated COFs material in detecting uranium in water.

[0032] Furthermore, the application method comprises the following steps: adding the amidoximated COFs material to a solvent to prepare a stock solution with a concentration of 1 to 25 mg / L, adding a uranyl ion solution to the stock solution with a concentration of 0 to 30 μM, testing the fluorescence emission spectrum before and after the addition of uranyl ions in a fluorescence spectrophotometer to obtain a change in fluorescence emission intensity, drawing a curve showing the change in fluorescence emission intensity versus uranium concentration, and then detecting the uranium concentration in the water body.

[0033] Preferably, the solvent is DMF, DMAc, ethanol, THF or water.

[0034] The present invention discloses the following technical effects:

[0035] The present invention first uses 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde as raw materials to prepare a COFs material with a cyano group. The amidoximated COFs material with the dual functions of adsorbing and detecting uranyl obtained by post-modification has high adsorption selectivity and fast adsorption kinetics for uranyl.

[0036] The prepared adsorption material of the present invention has unique and excellent adsorption performance for hexavalent uranium, is easy to recycle and recycle, and is environmentally friendly.

[0037] The material prepared by the present invention is simple in method, uses environmentally friendly, non-toxic and harmless raw materials with low cost, can be synthesized at room temperature, avoids the harsh conditions of traditional solvent thermal synthesis, and can also be used for fluorescence analysis to detect uranium with a low detection limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 SEM images of COF-AO, where a is low magnification and b is high magnification;

[0040] Figure 2 IR spectra of 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 3,4-diaminobenzonitrile, COF-CN, and COF-AO in Example 1;

[0041] Figure 3 The graph of the adsorption amount of hexavalent uranium of COF-AO at different concentrations versus adsorption time;

[0042] Figure 4 This is the cyclic regeneration performance diagram of the adsorption process of COF-AO;

[0043] Figure 5 The diagrams are the comparison of the adsorption amount of COF-AO for different metals in simulated seawater and the selectivity coefficients of COF-AO for different metals, where a is the adsorption amount comparison diagram and b is the selectivity coefficient diagram.

[0044] Figure 6 Specific surface area and pore distribution diagram of COF-AO, where a is the specific surface area and b is the pore distribution;

[0045] Figure 7 Solid-state NMR images of COF-AO and COF-CN;

[0046] Figure 8 Fluorescence excitation and emission spectra of COF-AO;

[0047] Figure 9 The fluorescence emission spectra of COF-AO added to different uranium concentrations and the fluorescence emission spectra of COF-AO added to 0-30μM UO2 2+ Fluorescence calibration curve within the concentration range, where a is the fluorescence emission spectrum and b is the fluorescence calibration curve. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0049] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0050] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0051] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] The raw materials and reagents used in the specific embodiment of the present invention are all commercially available products.

[0054] Example 1

[0055] The preparation steps of amidoximated COFs materials with dual functions of adsorption and detection of uranyl are as follows:

[0056] S1. Ultrasonic mixing of 3,4-diaminobenzonitrile, 2-hydroxy-1,3,5-benzenetricarboxaldehyde, and acetonitrile in a ratio of 3 mmol:2 mmol:250 mL (5 min) to obtain a mixed solution;

[0057] S2. Add acetic acid solution with an initial concentration of 12 M to the mixed solution, with the volume ratio of acetic acid solution to the mixed solution being 7:50, stir for 10 minutes, and allow to react at room temperature for 3 days. After the reaction is completed, centrifuge, wash the reaction product with ethanol several times, and vacuum dry it at 60°C for 24 hours to obtain a cyanated COFs material, which is recorded as COF-CN;

[0058] S3. Mix the cyanated COFs material, hydroxylamine hydrochloride, anhydrous potassium carbonate, anhydrous ethanol and ultrapure water in a ratio of 1g:2g:2g:270mL:30mL, stir and reflux under nitrogen protection, heat in an oil bath at 85°C for 8h, centrifuge after the reaction, repeatedly wash the reaction product with water and ethanol, and vacuum dry at 60°C for 24h to obtain the amidoximated COFs material, recorded as COF-AO.

[0059] Example 2

[0060] Compared with Example 1, the only difference is that the mass ratio of the cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate is 1:1.5:2.

[0061] Example 3

[0062] Compared with Example 1, the only difference is that the mass ratio of the cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate is 1:2:1.5.

[0063] Example 4

[0064] Compared with Example 1, the only difference is that the molar ratio of 2-hydroxy-1,3,5-benzenetricarboxaldehyde to 3,4-diaminobenzonitrile is 1:1.

[0065] Example 5

[0066] Compared with Example 1, the only difference is that the molar ratio of 2-hydroxy-1,3,5-benzenetricarboxaldehyde to 3,4-diaminobenzonitrile is 3:1.

[0067] Example 6

[0068] Compared with Example 1, the only difference is that the number of days for the static reaction in step S2 is 4 days.

[0069] Example 7

[0070] Compared with Example 1, the only difference is that the number of days for the static reaction in step S2 is 5 days.

[0071] Example 8

[0072] Compared with Example 1, the only difference is that the oil bath heating time in step S3 is 7 hours.

[0073] Example 9

[0074] Compared with Example 1, the only difference is that the oil bath heating time in step S3 is 9 hours.

[0075] Example 10

[0076] Compared with Example 1, the only difference is that the oil bath heating time in step S3 is 10 hours.

[0077] Comparative Example 1

[0078] The preparation steps of amidoximated COFs materials are as follows:

[0079] S1. Ultrasonic mixing of terephthalonitrile, 1,3,5-tris-(4-formylphenyl)benzene, n-butanol, and o-chlorodiphenyl in a ratio of 4 mmol:1 mmol:2.5 mL:22.5 mL was performed (5 min) to obtain a mixed solution;

[0080] S2. The prepared mixed solution was then subjected to three liquid nitrogen freeze-thaw cycles and sealed under vacuum. After heating at 120°C for three days, the wet solid was transferred to tetrahydrofuran (THF) and ethanol for Soxhlet extraction and washing for three days. After vacuum drying at 100°C for 10 hours, the cyanated COFs material was obtained, which was designated as HDU-102.

[0081] S3. HDU-102 (100 mg) was soaked in anhydrous ethanol (17.5 mL) for 20 min and then reacted with hydroxylamine hydrochloride (0.445 g) and trimethylamine (0.9 mL) at 85°C for 6 h. The product was then washed with ethanol and ultrapure water and dried at room temperature to obtain the amidoximated COFs material, designated HDU-102-AO.

[0082] Test Example 1

[0083] Adsorption experiment:

[0084] The amidoximated COFs material prepared in Example 1 was added as an adsorbent into 50 mL of uranyl solution (concentration: 100 mg / L), with the adsorbent dosage being 0.5 mg, 1 mg, or 2 mg.

[0085] Test Example 2

[0086] Detection experiment:

[0087] The amidoximated COFs materials prepared in Example 1 and Comparative Example 1 were added to DMF to prepare stock solutions of 1 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L, and then mixed with uranyl ion solutions of different concentrations (0-30 μM). The fluorescence emission spectra were measured on a fluorescence spectrophotometer.

[0088] When the amidoximated COF material prepared in Comparative Example 1 was added to DMF, no fluorescence phenomenon occurred.

[0089] Figure 1 The SEM image of COF-AO, where a is low magnification and b is high magnification, is shown in Figure 2. Figure 1It can be seen that the amidoximated COFs material has a porous rod-like structure, and the porous structure is conducive to the adsorption of uranium.

[0090] Figure 2 is the infrared spectrum of 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 3,4-diaminobenzonitrile, COF-CN and COF-AO in Example 1, Figure 2 It can be seen that -CHO (~1688cm -1 ) and the stretching vibration peak of -NH2 (~3440cm -1 ) completely disappeared, and the vibration peak of C=N (~1644cm -1 ) characteristic new peak, proving the successful synthesis of COF-CN. Compared with COF-CN, in the infrared spectrum of COF-AO, -CN (~2226cm -1 ) vibration peak disappears, and CN (~1483cm -1 ) and NO(~931cm -1 ), proving the successful oximation of the amidine and indicating the successful synthesis of the material.

[0091] Figure 3 The graph of the adsorption amount of COF-AO for different concentrations of hexavalent uranium (concentrations of 25 mg / L, 50 mg / L, and 100 mg / L) versus adsorption time is shown in Figure 2. Figure 3 It can be seen that the COF-AO material can reach a uranium adsorption capacity of more than 229.9 mg / g within 45 min, with rapid adsorption kinetics (5.11 mg / g / min).

[0092] The COF-AO prepared in Example 1 was subjected to a cyclic regeneration experiment. The steps were as follows: After the COF-AO first adsorbed uranium and reached adsorption equilibrium, the COF-AO was regenerated using a Na2CO3 solution with a pH of 11 as the eluent and stirred for 1 hour. The resulting suspension was filtered and washed multiple times with ultrapure water. The resulting material was dried and used in another adsorption experiment. The results are shown in Figure 2. Figure 4 shown.

[0093] Figure 4 The performance diagram of the COF-AO adsorption process cycle regeneration is shown in Figure 2. Figure 4 It can be seen that COF-AO as a uranium adsorbent still has strong adsorption performance after 5 cycles of regeneration, indicating that the adsorption material of the present invention has stable performance and high reuse rate.

[0094] The COF-AO prepared in Example 1 was subjected to a uranium adsorption experiment in simulated seawater to determine its adsorption effect on hexavalent uranium. The steps were as follows: a 1L simulated seawater (UO2 2+ ,Ba 2+ ,Ca 2+ ,Cu 2+ ,Fe 3+ ,Mg 2+ , Na + ,VO3 - ), the concentration was 300μg / L, 2mg COF-AO was added, stirred and adsorbed for 24h, and tested by ICP-MS. The experimental results are as follows Figure 5 shown.

[0095] Figure 5 The adsorption amount comparison diagram of COF-AO for different metals in simulated seawater and the selectivity coefficient diagram of COF-AO for different metals are shown in Figure 1, where a is the adsorption amount comparison diagram and b is the selectivity coefficient diagram. Figure 5 It can be seen that after 24 h of adsorption in 1 L of simulated seawater, COF-AO has a high selectivity for uranium.

[0096] The COF-AO prepared in Example 1 was subjected to nitrogen adsorption-desorption test, and the results were as follows: Figure 6 shown.

[0097] Figure 6 The specific surface area and pore distribution diagram of COF-AO, where a is the specific surface area and b is the pore distribution. Figure 6 It can be seen that COF-AO has a mesoporous structure, and the porous structure is conducive to the adsorption of uranium.

[0098] The COF-AO and COF-CN prepared in Example 1 were 13 C solid-state nuclear magnetic test, the experimental results are as follows Figure 7 shown.

[0099] Figure 7 is the solid-state NMR image of COF-AO and COF-CN, Figure 7 It can be seen that the solid 13 In the CNMR spectrum, the cyano group at 107 ppm disappeared and was replaced by the amidoxime group at 161 ppm, confirming the conversion of the cyano group to the amidoxime group and demonstrating the successful synthesis of COF-AO.

[0100] The COF-AO prepared in Example 1 was subjected to fluorescence testing, and the experimental results are as follows: Figure 8 shown.

[0101] Figure 8The fluorescence excitation and emission spectra of COF-AO are shown in Figure 2. Figure 8 It can be seen that the optimal excitation wavelength of COF-AO is 220 nm, and the optimal emission wavelength is 465 nm.

[0102] The 1 mg / L COF-AO stock solution (2.7 mL) prepared in Example 1 was added to test solutions with different uranium concentrations (0-30 μM), and fluorescence testing was performed.

[0103] Figure 9 The fluorescence emission spectra of COF-AO added to different uranium concentrations and the fluorescence emission spectra of COF-AO added to 0-30μM UO2 2+ Fluorescence calibration curve within the concentration range, where a is the fluorescence emission spectrum and b is the fluorescence calibration curve. Figure 9 It can be seen that the fluorescence intensity of COF-AO weakens with the increase of uranium concentration until it is basically quenched.

[0104] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing amidoximated COFs material with dual functions of adsorption and detection of uranyl, characterized in that the steps include: Using 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde as raw materials, cyanated COFs materials were obtained after reaction; The cyanated COFs material is subjected to amidoximation modification to obtain the amidoximated COFs material having the dual functions of adsorbing and detecting uranyl.

2. The preparation method according to claim 1, characterized in that The preparation steps of the cyanated COFs material include: Ultrasonic mixing of 3,4-diaminobenzonitrile, 2-hydroxy-1,3,5-benzenetricarboxaldehyde and acetonitrile to obtain a mixed solution; Add acetic acid to the mixed solution and stir, then allow to react at room temperature. After the reaction is complete, centrifuge, wash, and vacuum dry to obtain a cyanated COFs material.

3. The preparation method according to claim 2, characterized in that The molar ratio of the 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde is 3:1-5; the volume ratio of the sum of the molar amounts of 3,4-diaminobenzonitrile and 2-hydroxy-1,3,5-benzenetricarboxaldehyde to acetonitrile is 4-8 mmol:250 mL; the concentration of the acetic acid is 12 M; and the volume ratio of the acetic acid to the mixed solution is 7:

50.

4. The preparation method according to claim 2, characterized in that The ultrasonic mixing time is 5 to 10 minutes; the stirring time is 10 minutes; and the static reaction time is 3 to 5 days.

5. The preparation method according to claim 1, characterized in that The amidoximation modification step comprises: The cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate are mixed with ethanol and water, and heated and stirred under nitrogen protection for reaction. After the reaction is completed, the solid product is collected by centrifugation, washed and vacuum dried to obtain the amidoximated COFs material with the dual functions of adsorbing and detecting uranyl.

6. The preparation method according to claim 5, characterized in that The mass ratio of the cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate is 1:1~10:1~10; the ratio of the sum of the mass of the cyanated COFs material, hydroxylamine hydrochloride and anhydrous potassium carbonate to the sum of the volumes of ethanol and water is 3~21g:300mL; the volume ratio of the ethanol and water is 9:

1.

7. The preparation method according to claim 5, characterized in that The heating temperature is 70-90° C.; the stirring time is 6-10 hours.

8. An amidoximated COFs material prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the amidoximated COFs material as claimed in claim 8 as an adsorption material for adsorbing uranium in water.

10. Use of the amidoximated COFs material according to claim 8 in detecting uranium in water.

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