A kind of amine functionalized covalent organic framework material and its preparation method and application in adsorption of radioactive iodine

Abstract

The present invention belongs to the field of functionalized materials and application technology, and relates to an amine-functionalized covalent organic framework material, a preparation method thereof, and an adsorption application for radioactive iodine. Toluene-2,4-diisocyanate and an aminating material are used to achieve post-modification functionalization of a hydroxyl-containing porous material under mild conditions. The amine-functionalized organic covalent framework material prepared by the present invention has a large specific surface area and a permanently developed pore structure, with many reactive functional groups and easy modification. It has excellent iodine adsorption capacity in both gas and liquid phases, can be recycled and reused, and is energy-saving and environmentally friendly. The preparation method of the present invention is simple, efficient, highly safe, and has low equipment requirements. It provides a universal method for strengthening the interaction between neutral molecules and the host material, is suitable for large-scale industrial production, and has broad market prospects.

Description

Technical field:

[0001] This invention belongs to the field of functionalized materials and their applications, specifically relating to amine-functionalized covalent organic framework materials, their preparation methods, and their applications in the adsorption of radioactive iodine. Specifically, the invention relates to a synthesis process for post-modified functionalized covalent organic framework materials, enabling efficient synthesis under relatively mild conditions. This process involves introducing amine functional groups through chemical reactions to modify the structure of porous materials, as well as the application of these materials in areas such as gas adsorption and nuclear wastewater treatment. Background technology:

[0002] Nuclear energy is considered one of the most efficient and long-term carbon-free energy sources, but it produces a large amount of radioactive waste during the fuel reprocessing process. Especially after the Fukushima nuclear accident, the treatment of nuclear waste and nuclear wastewater has become an international focus. Nuclear waste contains some radioactive elements, such as 129 I. 90 Sr. 131 I, and 106 Ru. Among them, 129 Iodine has a long half-life of 1.57 million years, posing a long-term risk to the biosphere. In particular, iodine molecules dissolved in water can be easily ingested by humans through the food chain, potentially damaging the thyroid gland and causing other health problems. Therefore, radioactive elements, particularly radioactive iodine, must be captured from nuclear waste and contaminated water before release into the ecosystem to ensure the safe use of nuclear energy.

[0003] Covalent organic frameworks (COFs) are porous crystalline structures formed by organic molecules linked by covalent bonds, with highly ordered pore structures and adjustable chemical functions. Compared with traditional metal-organic frameworks (MOFs), the building blocks of COFs are organic molecules linked by covalent bonds, rather than metal ions. Due to this structural characteristic, COFs exhibit softer and more diverse porous properties, giving them more flexibility in functionalization. For example, by introducing nucleophilic groups, such as imine bonds generated by Schiff base reactions, their affinity for radioactive iodine can be effectively improved, and the introduction of carboxyl groups (-COOH) can improve the adsorption performance of COFs for metal ions, making them suitable for heavy metal removal and catalytic reactions. These functionalized materials have shown broad application potential in multiple fields due to their high specific surface area, adjustable porosity and excellent stability, especially in water pollution adsorption, gas storage and adsorption.

[0004] Recently, Fu, Liu, and others reported the use of AC4trimTpPaSO3 for radioiodine adsorption. Using a COF with sulfonic acid groups as a raw material, AC4trimTpPaSO3 was modified with aminotriazole cations onto the anionic COF via an ionic liquid solution process (ILSP). This resulted in a five-fold improvement in the iodine adsorption kinetics (K80% rate) of the ionic liquid (IL)-modified COF (AC4tirmTpPaSO3) compared to the original COF. In their work, Tang and Huang employed IL-induced dynamic complexation of iodine anions within an IL@MOF composite, enhancing its electrostatic adsorption capacity and resulting in a highly efficient iodine capture adsorbent. However, the synthesis of ionic liquids is typically complex, requiring precise reaction conditions and high-purity raw materials, resulting in high synthesis costs. While the low volatility of ionic liquids reduces air pollution, their poor biodegradability can lead to long-term environmental persistence and potential long-term pollution. The high viscosity of ionic liquids during COF modification also makes washing difficult, making it crucial to identify suitable alternative materials to ionic liquids to enhance the adsorption capacity of COFs. Summary of the invention:

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an amine-functionalized covalent organic framework material, a preparation method thereof, and an application for the adsorption of radioactive iodine. The amine-functionalized covalent organic framework material is obtained by post-modifying COF with toluene diisocyanate (TDI) and N-aminoethylpiperazine (AEP). The material has high stability and strong ability to adsorb pollutants in liquid and gas phases.

[0006] To achieve the above objectives, the present invention provides an amine-functionalized covalent organic framework material, which is obtained by post-modifying a hydroxyl-containing porous material with toluene diisocyanate (TDI) and an aminating material. The hydroxyl-containing porous material is one or more of TpPa-OH-COF, MOF-808, and MXene. The TpPa-OH-COF is formed by condensing 2,5-diaminobenzene-1,4-diol dihydrochloride (Pa-(OH)2·2HCl) and trialdehyde phloroglucinol (TP). The MXene is titanium carbide. The aminating material is a piperazine compound with an amino group.

[0007] The present invention also provides a method for preparing the amino-functionalized organic covalent framework material, which comprises the following steps:

[0008] (1) adding a hydroxyl-containing porous material powder to dimethyl sulfoxide, stirring uniformly to obtain a suspension, adding toluene-2,4-diisocyanate (TDI) to the suspension, stirring uniformly, reacting at room temperature for 12 to 18 hours, separating the solid and the liquid, and drying to obtain a toluene-2,4-diisocyanate-modified porous material; the hydroxyl-containing porous material is one or more of TpPa-OH-COF, MOF-808, and MXene;

[0009] (2) adding toluene-2,4-diisocyanate modified porous material powder to the aminated material, stirring and reacting at room temperature for 24 hours, finally, separating the solid and the liquid, washing the solid with dimethylformamide and 1,4-dioxane in turn, and freeze-drying to obtain an amino-functionalized organic covalent framework material; the aminated material is a piperazine compound with an amino group.

[0010] In the above step (1), the mass ratio of the hydroxyl-containing porous material powder to toluene-2,4-diisocyanate is 1:(2-3).

[0011] The stirring reaction at room temperature in the above step (2) must be carried out under a nitrogen atmosphere.

[0012] Preferably, the drying in step (1) must be carried out under vacuum freezing conditions for 24 hours.

[0013] In a preferred embodiment, in step (2) of the above method, the degree of amino functionalization of the final product can be controlled by controlling the ratio of the hydroxyl-containing porous material to toluene-2,4-diisocyanate.

[0014] The amination material is N-aminoethylpiperazine (AEP) or N-(2-aminoethyl)piperazine-1,4-diethylamine (AEPD) or other piperazine compounds with amino groups.

[0015] The TpPa-OH-COF of the present invention is prepared by condensing 2,5-diaminobenzene-1,4-diol dihydrochloride (Pa-(OH)2·2HCl) and trialdehyde phloroglucinol (TP). The specific preparation method is as follows:

[0016] Trialdehyde phloroglucinol (TP) and 2,5-diaminobenzene-1,4-diol dihydrochloride (Pa-(OH)2·2HCl) were added to a mixed solvent containing mesitylene and 1,4-dioxane to obtain a suspension. Acetic acid was added to the suspension and ultrasonicated to form a reaction system I. The reaction system I was added to a reactor and nitrogen was introduced to expel air. The system was then calcined at 120°C under vacuum for three days. Finally, the solid-liquid separation was performed, and the solid was washed with dimethylformamide and 1,4-dioxane in sequence and dried under vacuum to obtain TpPa-OH-COF powder.

[0017] The mixed solvent containing mesitylene and 1,4-dioxane of the present invention is prepared by mixing mesitylene and 1,4-dioxane in a volume ratio of 1:1.

[0018] The molar ratio of the trialdehyde phloroglucinol to 2,5-diaminobenzene-1,4-diol dihydrochloride is 2:3.

[0019] The concentration of acetic acid in the reaction system I of the present invention is 6M, and the volume ratio of acetic acid to the mixed solvent is 1:3-5.

[0020] The vacuum drying temperature of the present invention is 80° C. and the time is 24 hours.

[0021] The present invention also provides an amino-functionalized organic covalent framework material prepared by the above preparation method.

[0022] The present invention also provides application of the above-mentioned amino-functionalized organic covalent framework material in adsorbing radioactive iodine gas.

[0023] The present invention also provides application of the amino-functionalized organic covalent framework material in adsorbing iodine in a liquid phase.

[0024] The present invention also provides the use of the amino-functionalized organic covalent framework material in nuclear waste gas adsorption or nuclear sewage treatment, which can adsorb iodine in nuclear waste gas or nuclear sewage.

[0025] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0026] (1) The present invention utilizes toluene diisocyanate (TDI) and N-aminoethylpiperazine (AEP) to post-modify hydroxy COF to form a covalent organic framework adsorbent with high selectivity, good reproducibility, and convenient solid-liquid separation, which can efficiently adsorb and remove radioactive iodine from liquid and gas phases;

[0027] (2) The TpPa-TDI-AEP prepared by the present invention has a large specific surface area, a large number of reactive functional groups in the material, and is easy to modify; the amino-based COF material TpPa-TDI-AEP has a permanently open pore structure;

[0028] (3) The amino-based COF adsorbent of the present invention exhibited excellent iodine adsorption capacity in the gas phase and liquid phase, which were 6.81 g / g and 1570.50 mg / g, respectively, which were 2.4 times and 5 times higher than those of the unmodified covalent organic framework material. After repeating 5 times, the selective adsorption rate of iodine was still as high as 85.63%.

[0029] (4) The TpPa-TDI-AEP prepared in the present invention has a strong affinity for iodine molecules; the amino-functionalized covalent organic framework material reacts with iodine molecules to dynamically form a polyiodine complex, which has a strong electrostatic interaction with the covalent organic framework. Due to the reversibility of polyiodide formation, the composite material also exhibits excellent recyclability. This work provides a general method for strengthening the interaction between neutral molecules and host materials, which can find application in various adsorption-based separation processes.

[0030] (5) The material modification scheme of the present invention is achieved by stirring COF powder in a solvent at room temperature. The method is simple, efficient, safe, requires low equipment, is energy-saving and environmentally friendly, is easy to monitor, improves the uniformity and stability of the product, and is suitable for large-scale industrial production.

[0031] In summary, the amino-functionalized organic covalent framework material prepared by the present invention has a huge specific surface area and a permanently developed pore structure, has many reactive functional groups, and is easy to modify; it has excellent iodine adsorption capacity in both gas and liquid phases, can be recycled and reused, and is energy-saving and environmentally friendly; the preparation method of the present invention is simple, efficient, highly safe, and has low equipment requirements. It provides a general method for strengthening the interaction between neutral molecules and the main material, is suitable for large-scale industrial production, and has broad market prospects. Description of the drawings:

[0032] Figure 1 Schematic diagram of the structure of the COF prototype (TpPa-OH-COF) involved in the present invention.

[0033] Figure 2 The present invention relates to the preparation process and structural diagram of the amino-functionalized organic covalent framework TpPa-TDI-AEP.

[0034] Figure 3 This is a SEM image of TpPa-OH-COF prepared in Example 1 of the present invention.

[0035] Figure 4 This is a SEM image of TpPa-TDI-AEP prepared in Example 1 of the present invention.

[0036] Figure 5 These are FTIR graphs of TpPa-OH-COF, TpPa-TDI-AEP and two precursors prepared in Example 1 of the present invention.

[0037] Figure 6 The TpPa-OH-COF and TpPa-TDI-AEP branches (SI and S-II) prepared in Example 1 of the present invention are simulated with DFT calculations of iodine molecules.

[0038] Figure 7 This is a graph showing the regeneration performance of TpPa-TDI-AEP prepared in Example 1 of the present invention after iodine adsorption. Specific implementation method:

[0039] The present invention will be described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0040] Example 1:

[0041] This embodiment relates to a method for preparing an amine-functionalized organic covalent framework material, and the specific steps are as follows:

[0042] Step 1: 0.3 mmol of trialdehyde phloroglucinol (TP) and 0.45 mmol of 2,5-diaminobenzene-1,4-diol dihydrochloride (Pa-(OH)2·2HCl) were added to 3 mL of a mixed solution containing mesitylene and 1,4-dioxane to obtain a suspension, and then 0.7 mL of acetic acid was added to the suspension, and ultrasonication was performed to obtain a uniform dispersion. The concentration of acetic acid in the dispersion was 6 M. Then, N2 was filled into the reactor to remove air, and then the reactor was sealed. The reactor was placed in an oven at 120°C and calcined for 3 days to obtain a TpPa-OH-COF sample. Finally, the obtained sample was thoroughly washed with an organic solvent until the solution was clear, centrifuged, and the sample obtained after centrifugation was dried in a vacuum chamber at 80°C for 24 hours to obtain purified TpPa-OH-COF.

[0043] The mixed solution is prepared by mixing mesitylene and 1,4-dioxane in a volume ratio of 1:1;

[0044] Step 2: 50 mg of the prepared purified TpPa-OH-COF powder and 30 mL of dimethyl sulfoxide (DMSO) were placed in a 100 mL flask; then 120 mg of toluene-2,4-diisocyanate (TDI) was added, and the mixture was stirred continuously for 18 hours. The resulting precipitate was thoroughly washed with dioxane and centrifuged, and freeze-dried to obtain the product TpPa-TDI;

[0045] Step 3: The obtained TpPa-TDI (60 mg) was placed in another 100 mL flask, and 25 mL of N-aminoethylpiperazine (AEP) was added. The mixture was stirred at 25°C under N2 atmosphere for 24 h. The obtained precipitate was thoroughly washed with dioxane and freeze-dried to obtain an amino-functionalized organic covalent framework material, which was recorded as TpPa-TDI-AEP.

[0046] The prepared TpPa-OH-COF and TpPa-TDI-AEP were characterized by SEM. Figure 3 and Figure 4 As shown. Figure 3In the study, TpPa-OH-COF exhibited a nanoribbon morphology with diameters of 100-250 nm. In contrast, TpPa-TDI-AEP exhibited a more fluffy cauliflower-like structure. Furthermore, randomly stacked TpPa-TDI-AEP nanosheets were observed. This morphological transformation is associated with the reorganization of the crystal structure and the corresponding space-filling effect resulting from the introduction of amine groups. The amine groups introduced greater steric hindrance within the framework, promoting the formation of more complex and diverse structures. The cauliflower-like morphology not only increased the material's porosity but also provided more active sites for molecular adsorption and reaction.

[0047] The functional group characteristics of TP, Pa-(OH)2·2HCl, TpPa-OH-COF and TpPa-TDI-AEP were studied by Fourier transform infrared spectroscopy (FT-IR). Figure 5 As shown. The aldehyde group of TP condenses with the amino group of Pa-(OH)2·2HCl through the Schiff base reaction to generate TpPa-OH-COF. The HC=O peak of TP and Pa-(OH)2·2HCl belong to -NH 2 The vibration bands of TpPa-OH-COF disappear together. In the Fourier transform infrared spectrum of TpPa-OH-COF, at 3350 cm -1 A broad peak attributable to OH stretching vibration was observed nearby, corresponding to the spectrum of Pa-(OH)2·2HCl at the same position. -1 The peaks at 3220 cm-1 are attributed to the formation of C-N bonds and C=O bonds, respectively. -1 A characteristic NH peak was observed at 3350 cm-1, which was formed by the condensation of the -NH2 group of Pa-(OH)2·2HCl and the hydroxyl group of TP. Compared with TpPa-OH-COF, TpPa-TDI-AEP has a -1 The hydroxyl vibration peak at 1620 cm disappeared, indicating that the cyanate group of TDI reacted successfully with the -OH group of TpPa-OH-COF. -1 The CN peak at is significantly stronger, which is due to the increase of CN bonds in the reaction between TDI and AEP, indicating the success of amine functionalization.

[0048] Example 2:

[0049] This embodiment relates to a method for preparing an amine-functionalized organic covalent framework material, and the specific steps are as follows:

[0050] Step 1: 0.3 mmol of trialdehyde phloroglucinol, 0.45 mmol of 2,5-diaminobenzene-1,4-diol dihydrochloride, 3 mL of a mixed solution containing mesitylene and 1,4-dioxane, and 0.7 mL of acetic acid were added to a reactor, and ultrasonicated to obtain a uniform dispersion. The concentration of acetic acid in the dispersion was 6 M. Then, nitrogen was introduced into the reactor to remove air, and the reactor was sealed. The reactor was placed in an oven at 120°C and calcined for 3 days to obtain a TpPa-OH-COF sample. Finally, the obtained sample was thoroughly washed with an organic solvent until the solution was clear, centrifuged, and the sample obtained after centrifugation was dried in a vacuum chamber at 80°C for 1 day to obtain purified TpPa-OH-COF.

[0051] The mixed solution is prepared by mixing mesitylene and 1,4-dioxane in a volume ratio of 1:1;

[0052] Step 2: 50 mg of the prepared purified TpPa-OH-COF powder and 30 mL of dimethyl sulfoxide (DMSO) were placed in a 100 mL flask, and then 120 mg of toluene-2,4-diisocyanate (TDI) was added. The mixture was stirred continuously for 18 h. The resulting precipitate was thoroughly washed with dioxane and centrifuged, and freeze-dried to obtain the product TpPa-TDI;

[0053] Step 3: The obtained TpPa-TDI (60 mg) was placed in another 100 mL flask, and 30 ml of DMSO and 100 mg of N-(2-aminoethyl)piperazine-1,4-diethylamine (AEPD) were added. The mixture was stirred at 25 ° C. under N2 atmosphere for 24 h. The obtained precipitate was thoroughly washed with dioxane and freeze-dried to obtain an amino-functionalized organic covalent framework material, which was recorded as TpPa-TDI-AEPD.

[0054] Example 3:

[0055] This embodiment relates to a method for preparing an amine-functionalized MXene material, and the specific steps are as follows:

[0056] Step 1: First, 3g of Ti3AlC2 as the raw material for synthesizing MXene was added to a 100mL polytetrafluoroethylene reactor, and then 60mL of hydrofluoric acid was added dropwise to the reaction system. After mixing evenly, the reactor was sealed and reacted at 70°C for 48h. After that, the mixture was taken out and washed with ultrapure water and dried in a vacuum drying oven. Then, 1.8g of the dried powder was dispersed in 40mL DMSO and intercalated at 70°C for 18h. After completion, it was washed with ultrapure water and vacuum dried for 24h to obtain MXene.

[0057] Step 2: 200 mg of the prepared MXene and 30 mL of dimethyl sulfoxide (DMSO) were placed in a 100 mL flask, and then 120 mg of toluene-2,4-diisocyanate (TDI) was added. The mixture was stirred continuously for 18 h, washed thoroughly with dioxane, centrifuged, and freeze-dried to obtain MXene-TDI.

[0058] Step 3: Place the obtained MXene-TDI in another 100 mL flask, add 25 mL AEP, and stir the mixture at 25 ° C and N2 atmosphere for 24 hours. The obtained precipitate is thoroughly washed with dioxane and freeze-dried to obtain an amino-functionalized organic covalent framework material, which is recorded as MXene-TDI-AEP.

[0059] Comparative Example 1:

[0060] This comparative example is to prepare a prototype COF without post-modification, namely TpPa-OH-COF, and the specific steps are as follows: 0.3 mmol of trialdehyde phloroglucinol, 0.45 mmol of 2,5-diaminobenzene-1,4-diol dihydrochloride, 3 mL of a mixed solution containing mesitylene and 1,4-dioxane, and 0.7 mL of acetic acid are added to a reactor, and ultrasonication is performed to obtain a uniform dispersion, wherein the concentration of acetic acid in the dispersion is 6 M; then, N2 is filled into the reactor to remove air, and then the reactor is sealed; the reactor is placed in an oven at 120°C and calcined for 3 days to obtain a TpPa-OH-COF sample; finally, the obtained TpPa-OH-COF sample is thoroughly washed with an organic solvent until the solution is clear, centrifuged, and the sample obtained after centrifugation is dried in a vacuum chamber at 80°C for 1 day to obtain purified TpPa-OH-COF.

[0061] Comparative Example 2:

[0062] This comparative example is to prepare COF modified with only TDI, namely TpPa-TDI, and the specific steps are as follows:

[0063] Step 1: 0.3 mmol of trialdehyde phloroglucinol, 0.45 mmol of 2,5-diaminobenzene-1,4-diol dihydrochloride, 3 mL of a mixed solution containing mesitylene and 1,4-dioxane, and 0.7 mL of acetic acid were added to a reactor, and ultrasonication was performed to obtain a uniform dispersion. The concentration of acetic acid in the dispersion was 6 M. Then, nitrogen was introduced into the reactor to remove air, and the reactor was sealed. The reactor was placed in an oven at 120° C. and calcined for 3 days to obtain a TpPa-OH-COF sample. Finally, the obtained TpPa-OH-COF sample was thoroughly washed with an organic solvent until the solution was clear, centrifuged, and the sample obtained after centrifugation was dried in a vacuum chamber at 80° C. for 1 day to obtain purified TpPa-OH-COF.

[0064] Step 2: 50 mg of the prepared TpPa-OH-COF powder and 30 mL of dimethyl sulfoxide (DMSO) were placed in a 100 mL flask; then 60 mg of toluene-2,4-diisocyanate (TDI) was added, and the mixture was stirred continuously for 18 h. The mixture was thoroughly washed with dioxane and centrifuged, and freeze-dried to obtain TpPa-TDI.

[0065] Example 4:

[0066] This example involves a comparative experiment on the radioactive iodine adsorption effects of TpPa-TDI-AEP prepared in Example 1, TpPa-OH-COF prepared in Comparative Example 1, and TpPa-TDI prepared in Comparative Example 2 in gas phase and liquid phase, as follows:

[0067] The TpPa-TDI-AEP prepared in Example 1 was placed in 50 ml of an iodine-containing n-hexane solution. The residual iodine concentration in the solution after adsorption was measured using a UV-visible spectrophotometer (TU-1810, Beijing General Instrument Co., Ltd.) at an ambient temperature of 25°C, an initial iodine concentration of 500 mg / L, and an adsorption time of 96 hours. The iodine adsorption capacity of TpPa-TDI-AEP in the liquid phase was measured to be 1570.50 mg / g. The iodine vapor (I2) adsorption capacity of TpPa-TDI-AEP was investigated gravimetrically by placing 10 mg of TpPa-TDI-AEP and 0.5 g of iodine in a sealed container, evaporating the iodine at an ambient temperature of 75°C, and adsorbing for 72 hours. The iodine adsorption capacity of TpPa-TDI-AEP in the gas phase was measured to be 6.81 g / g.

[0068] The TpPa-OH-COF prepared in Comparative Example 1 was placed in 50 ml of iodine-containing n-hexane solution. The residual concentration of the iodine solution after adsorption was measured using a UV-Vis spectrophotometer (TU-1810, Beijing General Instrument Co., Ltd.) at an ambient temperature of 25°C, an initial iodine concentration of 500 mg / L, and an adsorption time of 96 hours. The iodine adsorption capacity of TpPa-OH-COF in the liquid phase was measured to be 327.41 mg / g. The iodine vapor (I2) adsorption capacity of TpPa-TDI-AEP was investigated gravimetrically by placing 10 mg of TpPa-OH-COF and 0.5 g of iodine in a sealed container. The iodine was evaporated at an ambient temperature of 75°C and adsorbed for 72 hours. The iodine adsorption capacity of TpPa-OH-COF in the gas phase was measured to be 2.84 g / g.

[0069] The TpPa-TDI prepared in Comparative Example 2 was placed in 50 ml of an iodine-containing n-hexane solution. The residual iodine concentration in the solution after adsorption was measured using a UV-Vis spectrophotometer (TU-1810, Beijing General Instrument Co., Ltd.) at an ambient temperature of 25°C, an initial iodine concentration of 500 mg / L, and an adsorption time of 96 hours. The iodine adsorption capacity of TpPa-TDI in the liquid phase was measured to be 567.30 mg / g. The iodine vapor (I2) adsorption capacity of TpPa-TDI-AEP was investigated gravimetrically by placing 10 mg of TpPa-TDI and 0.5 g of iodine in a sealed container, evaporating the iodine at an ambient temperature of 75°C, and adsorbing for 72 hours. The iodine adsorption capacity of TpPa-TDI in the gas phase was measured to be 3.96 g / g.

[0070] The above description shows that the adsorption amount of iodine in the liquid phase and the gas phase by TpPa-TDI-AEP prepared in Example 1 is significantly higher than that of TpPa-OH-COF and TpPa-TDI.

[0071] Example 5:

[0072] In this example, density functional theory (DFT) calculations were performed on TpPa-OH-COF and TpPa-TDI-AEP to further explore the role of the grafted functional groups in promoting the adsorption of iodine molecules. Using SI (TpPa-OH-COF) and S-II (TpPa-TDI-AEP) as model molecules, DFT calculations were performed to obtain the optimized geometric structures between the host framework and the guest iodine and to calculate their binding energies with the iodine molecules, as shown in Figure 2. Figure 6 The calculated binding energy between SI and I2 is -28.05 kJ / mol, and the calculated binding energy between S-II and I2 is -80.34 kJ / mol, indicating that TpPa-TDI-AEP has a stronger affinity for iodine molecules.

[0073] Example 6:

[0074] This example relates to the regeneration experiment after iodine adsorption of TpPa-TDI-AEP prepared in Example 1. The iodine adsorption method of Example 4 is used to test the material. After the first iodine adsorption, the material is treated and the second iodine adsorption is performed. The material is recycled for 5 times. The iodine adsorption efficiency of each time is as follows: Figure 7 After five cycles of use, the ratio of the selective adsorption of iodine by TpPa-TDI-AEP to the initial adsorption was still as high as 85.63%, indicating that TpPa-TDI-AEP has excellent regeneration function.

Claims

1. An amine-functionalized covalent organic framework material, characterized in that: The hydroxyl-containing porous material is obtained by post-modification using toluene diisocyanate and an amination material; the amination material is a piperazine compound with an amino group; the hydroxyl-containing porous material is TpPa-OH-COF, and the TpPa-OH-COF is formed by condensation of 2,5-diaminobenzene-1,4-diol dihydrochloride and trialdehyde phloroglucinol.

2. A method for preparing the amino-functionalized covalent organic framework material according to claim 1, characterized in that: The specific steps are as follows: (1) Adding hydroxyl-containing porous material powder to dimethyl sulfoxide, stirring evenly to obtain a suspension, adding toluene-2,4-diisocyanate to the suspension, stirring evenly, stirring and reacting at room temperature, solid-liquid separation, freeze-drying, and obtaining a toluene-2,4-diisocyanate-modified porous material; (2) Adding toluene-2,4-diisocyanate modified porous material powder to an aminated material, stirring and reacting at room temperature, and finally, performing solid-liquid separation, solid washing, and freeze-drying to obtain an amino-functionalized covalent organic framework material; the aminated material is a piperazine compound with an amino group.

3. The method for preparing an amine-functionalized covalent organic framework material according to claim 2, wherein: The TpPa-OH-COF is prepared by condensing 2,5-diaminobenzene-1,4-diol dihydrochloride and trialdehyde phloroglucinol. The specific preparation method is as follows: Trialdehyde phloroglucinol (TP) and 2,5-diaminobenzene-1,4-diol dihydrochloride (Pa-(OH)2·2HCl) were added to a mixed solvent containing mesitylene and 1,4-dioxane to obtain a suspension. Acetic acid was added to the suspension and ultrasonicated to form a reaction system I. Reaction system I was added to a reactor and nitrogen was introduced to expel air. The system was then calcined in a vacuum for three days. Finally, solid-liquid separation was performed, the solid was washed, and vacuum drying was performed to obtain TpPa-OH-COF powder.

4. The method for preparing an amine-functionalized covalent organic framework material according to claim 3, wherein: The mixed solvent containing mesitylene and 1,4-dioxane is a mixture of mesitylene and 1,4-dioxane in a volume ratio of 1:1; the molar ratio of trialdehyde phloroglucinol and 2,5-diaminobenzene-1,4-diol dihydrochloride is 2:3; the concentration of acetic acid in the reaction system I is 6 M, and the volume ratio of acetic acid to the mixed solvent is 1:3~5.

5. The method for preparing an amino-functionalized covalent organic framework material according to claim 2, wherein: The mass ratio of the hydroxyl-containing porous material powder to toluene-2,4-diisocyanate is 1:(2~3); the stirring reaction at room temperature must be carried out under a nitrogen atmosphere.

6. The method for preparing an amino-functionalized covalent organic framework material according to claim 2, wherein: The amino functionalization degree of the final product is controlled by controlling the ratio of the hydroxyl-containing porous material to toluene-2,4-diisocyanate.

7. Use of the amine-functionalized organic covalent framework material according to claim 1 or the amine-functionalized organic covalent framework material prepared by the preparation method according to claim 2 in adsorbing radioactive iodine gas.

8. Use of the amine-functionalized organic covalent framework material according to claim 1 or the amine-functionalized organic covalent framework material prepared by the preparation method according to claim 2 in adsorbing iodine in a liquid phase.

9. Use of the amine-functionalized organic covalent framework material according to claim 1 or the amine-functionalized organic covalent framework material prepared by the preparation method according to claim 2 in nuclear waste gas adsorption or nuclear wastewater treatment, characterized in that: It can absorb iodine in nuclear waste gas or nuclear wastewater.

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