A supergravity method trifluoroacetic anhydride modified IRMOF-3 adsorbent and a preparation method and application thereof

Abstract

The application discloses a supergravity method trifluoroacetic anhydride modified IRMOF-3 adsorbent and a preparation method and application thereof, and belongs to the technical field of adsorption method iodine removal. The IRMOF-3 crystal material is synthesized by using a solvent thermal method. Then, a modified solution is prepared. After that, the obtained activated IRMOF-3 crystal powder is dispersed in the modified solution to form a suspension, and then the suspension is placed in a supergravity reactor to perform a reaction. Under the action of a huge shearing force generated by the supergravity field, the modified solution rapidly penetrates into the pore channel of the IRMOF-3, and trifluoroacetic anhydride is caused to contact the amino functional group of the IRMOF-3 and to occur amidation reaction, so that a trifluoromethyl-CF3 hydrophobic group is grafted on the pore channel surface and the outer surface of the IRMOF-3. Finally, the IRMOF-3 adsorbent is obtained by modification. The adsorption capacity of the prepared adsorbent is increased by 41.2% compared with that of the unmodified IRMOF-3 under the same conditions.

Description

Technical Field

[0001] This invention relates to a method for capturing radioactive iodine in nuclear waste gas, specifically to a trifluoroacetic anhydride-modified IRMOF-3 adsorbent prepared by supergravity and its application, belonging to the technical field of adsorption-based iodine removal. Background Technology

[0002] With the rapid development of nuclear energy, the treatment of radioactive waste gases generated during nuclear fuel reprocessing and nuclear accident handling has become increasingly prominent. Radioactive iodine isotopes (mainly...) 129 I and 131 (I) Due to its high volatility, long half-life, and tendency to accumulate in the human thyroid gland, it has become a key focus of nuclear facility exhaust gas treatment. During nuclear fuel reprocessing, spent fuel is usually dissolved in boiling acidic solutions (such as 3 M HNO3), resulting in exhaust gases containing not only radioactive iodine but also a large amount of water vapor. Water molecules and iodine species compete for adsorption on the adsorbent surface, significantly reducing iodine capture capacity and kinetic efficiency.

[0003] Metal-organic frameworks (MOFs) have shown broad application prospects in gas adsorption and separation due to their extremely high specific surface area, tunable pore structure, and abundant functional sites. Among them, IRMof-3, as a typical MOF material containing free amino (-NH2) functional groups, is considered an ideal matrix for iodine adsorption functionalization because its amino sites can be chemically modified to introduce specific functional groups. However, existing technologies have the following problems in practical applications: First, actual nuclear facility exhaust gases usually contain a certain amount of water vapor, and the competition between water molecules and iodine at adsorption sites is severe, resulting in a significant decrease in the iodine adsorption capacity of IRMof-3 in humid environments; Second, traditional post-modification methods (such as room temperature stirring) for functionalizing IRMof-3 usually suffer from long reaction times (several hours to several days), uneven mass transfer, and easy destruction of pore structure; Currently, there is a lack of a preparation method that can rapidly, efficiently, and uniformly introduce hydrophobic groups to improve the wet iodine adsorption performance of the material.

[0004] Therefore, developing a modified IRMOF-3 adsorbent material that combines high adsorption capacity, excellent humidity tolerance, and high efficiency is a key requirement for achieving efficient removal of radioactive iodine from post-treatment waste gas. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an adsorbent that utilizes supergravity technology to enhance the mass transfer process, rapidly hydrophobically modifying IRMof-3 with trifluoroacetic anhydride (TFAA), along with its preparation method and applications. This method, by introducing a strongly hydrophobic trifluoromethyl (-CF3) group, significantly improves the material's hydrophobicity in humid environments and its selective adsorption capacity for iodine vapor while maintaining the structural integrity of the IRMof-3 framework.

[0006] This invention discloses a method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent using a supergravity method, comprising the following steps: Step 1: Synthesize IRMOF-3 crystal material using a solvothermal method. Zinc nitrate hexahydrate and 2-aminoterephthalic acid were dissolved separately in organic solvents and mixed. A mixture of triethylamine and organic solvent was then added dropwise, and the mixture was heated to react. After the reaction was completed, the mixture was cooled, centrifuged, and washed with organic solvent. Finally, the product was dried under vacuum to obtain activated IRMOF-3 crystal powder. Step 2: Prepare the modified solution. Add trifluoroacetic anhydride (TFAA) dropwise to anhydrous dichloromethane (DCM) and mix thoroughly to prepare the modified solution; Step 3: Hypergravity reaction modification. The activated IRMof-3 crystal powder obtained in Step 1 is dispersed in the modification solution of Step 2 to form a suspension. The suspension is then placed in a hypergravity reactor for reaction. Under the enormous shear force generated by the hypergravity field, the modification solution rapidly penetrates into the pores of IRMof-3, promoting efficient contact between trifluoroacetic anhydride and the amino functional groups of IRMof-3 and causing an amidation reaction. Trifluoromethyl (-CF3) hydrophobic groups are grafted onto the pore surface and outer surface of IRMof-3. Step 4: Post-processing. The reacted material is centrifuged and repeatedly washed with anhydrous dichloromethane to remove unreacted trifluoroacetic anhydride. Finally, it is vacuum dried to obtain the modified IRMOF-3 adsorbent with -CF3 hydrophobic groups grafted onto its surface.

[0007] Further, the mass ratio of zinc nitrate hexahydrate, 2-aminoterephthalic acid, and triethylamine in step 1 is (0.04~0.06): (0.03~0.04): (1.4~1.6), preferably 0.05:0.036:1.45.

[0008] Further, in step 1, the organic solvent is N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), ethanol (EtOH), or methanol (MeOH); preferably ethanol; and ultrasonication is used during mixing, with the ultrasonic oscillation time being 1 to 10 minutes.

[0009] Furthermore, in step 1, the heating reaction temperature is 70~80℃, and the time is 1~3 hours.

[0010] Furthermore, in the modified solution of step 2, the volume ratio of trifluoroacetic anhydride (TFAA) to anhydrous dichloromethane (DCM) is 1:(500~125). Furthermore, in step 3, the mass ratio of IRMof-3 crystal powder to the volume ratio of the modified solution in the suspension is 10-20 mg / mL, preferably 15 mg / mL.

[0011] Furthermore, in step 3, the hypergravity reactor is a rotating packed bed or a high-speed centrifuge, the hypergravity level is controlled at 150~200 g (multiple of gravitational acceleration), the reaction temperature is room temperature, and the reaction time is 1~3 hours; the hypergravity level is preferably 179 g, and the reaction time is preferably 2 hours.

[0012] Furthermore, the vacuum drying temperature in steps 1 and 4 is 50~70℃, and the time is 10~14 hours.

[0013] This invention also discloses an application of a metal covalent organic framework material in iodine adsorption. The metal covalent organic framework material is prepared by the above-mentioned preparation method of metal covalent organic framework material and is used to capture gaseous iodine in a humid gas stream containing water vapor.

[0014] Step 1: Place the trifluoroacetic anhydride modified IRMOF-3 adsorbent for adsorption in a sealed adsorption container; for wet iodine adsorption, place a saturated salt solution in a sealed container to control the relative humidity of the system. Step 2: After adsorption is complete, open the sealed adsorption container and heat to desorb until the mass of the iodine-containing adsorbent no longer changes, at which point desorption is complete.

[0015] Further, in step 1, the ratio of the amount of trifluoroacetic anhydride modified IRMOF-3 adsorbent by the supergravity method to the amount of adsorbed iodine is (50~55) mg: 200 mg; the adsorption temperature is 65~85℃, preferably 80℃; and the adsorption time is 1~24 h.

[0016] Furthermore, in step 1, the relative humidity of the adsorption system is controlled to be 18% by adding a saturated calcium chloride solution to a sealed container.

[0017] Furthermore, in step 2, the desorption temperature is 140-160℃.

[0018] Beneficial effects of the present invention Compared with the prior art, the present invention has the following advantages: 1. Excellent wet iodine adsorption performance: By introducing strongly hydrophobic -CF3 groups on the surface of IRMOF-3 channels, the iodine adsorption capacity of the modified material reaches 1.92 g / g under static adsorption conditions of 80℃ and 18% relative humidity, which is 41.2% higher than the adsorption capacity of unmodified IRMOF-3 under the same conditions (1.36 g / g). Moreover, the adsorption capacity is maintained at 83.8% of that under dry conditions in a humid environment, which significantly improves the iodine capture ability of the material in a water vapor environment.

[0019] 2. High preparation efficiency and intact structure: The mass transfer process is enhanced by using the centrifugal method, shortening the reaction time from 24 hours required by the traditional room temperature stirring method to 2 hours, significantly improving the reaction efficiency. Furthermore, the modified material prepared by the centrifugal method exhibits intact crystal morphology under scanning electron microscopy, significantly superior to that prepared by the room temperature stirring method. This indicates that the rapid reaction effectively reduces the prolonged immersion of the IRMof-3 framework in solvents and byproducts, avoiding excessive damage to the pore structure.

[0020] 3. Good grafting uniformity: The micro-mixing characteristics of the supergravity field ensure the uniformity of TFAA grafting on the inner and outer surfaces of IRMOF-3. The EDS elemental distribution map shows that the F element is uniformly distributed on the material surface, avoiding the problems of local over-reaction or incomplete grafting.

[0021] 4. Good cycle stability: After 5 adsorption-desorption cycles, the material can still maintain more than 80% of the initial adsorption capacity. TG analysis shows that the material maintains good crystal structure stability and thermal stability during the cycle, and has excellent regeneration performance and practical application potential.

[0022] Based on the above reasons, the use of the modified IRMOF-3 adsorbent by the supergravity method of the present invention for radioactive iodine capture has advantages such as high adsorption capacity, excellent humidity tolerance, high preparation efficiency, and good regeneration performance, and can be widely promoted in the fields of nuclear waste treatment and radioactive waste gas purification. Attached Figure Description

[0023] Figure 1 The images shown are scanning electron microscope (SEM) images of the adsorbents prepared in Examples 1-4 and Comparative Examples 1-2 of this invention; wherein, a is IRMOF-3 (Comparative Example 1), b is IRMOF-3-CF3-40 (Example 1), c is IRMOF-3-CF3-80 (Example 2), d is IRMOF-3-CF3-120 (Example 3), e is IRMOF-3-CF3-160 (Example 4), and f is IRMOF-3-CF3-120. (Comparative Example 2); gk is the EDS elemental distribution map of IRMOF-3-CF3-120 (Example 3).

[0024] Figure 2 The XRD patterns are those of the adsorbents prepared in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0025] Figure 3 The graphs show the adsorption performance comparison of the adsorbents prepared in Example 3 and Comparative Example 1 of the present invention; wherein, (a) is the iodine vapor adsorption curve at 80℃, (b) is the water adsorption curve at 18% RH at 80℃, and (c) is the wet iodine vapor adsorption curve at 18% RH at 80℃.

[0026] Figure 4 The graphs show the stability and cycling performance of the adsorbent prepared in Example 4 of this invention; where (a) is the XRD pattern before and after adsorption cycle, (b) is the TG curve before adsorption and after desorption, and (c) is the performance graph of 5 adsorption-desorption cycles. Detailed Implementation

[0027] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Comparative Example 1 (1) Synthesis of IRMof-3: 0.05 g of zinc nitrate hexahydrate and 0.036 g of 2-aminoterephthalic acid were weighed, dissolved in ethanol, and sonicated for 5 min to mix evenly. 2 mL of triethylamine was added to 20 mL of ethanol and slowly added dropwise to the above mixed solution under magnetic stirring. The mixture was heated at 75 °C for 2 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The solid product was collected by centrifugation, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 60 °C for 12 hours to obtain activated IRMof-3 powder.

[0029] (2) Post-processing: The obtained product is used directly as an adsorbent without any modification treatment, and is denoted as IRMOF-3.

[0030] Example 1 (1) Synthesis of IRMof-3: 0.05 g of zinc nitrate hexahydrate and 0.036 g of 2-aminoterephthalic acid were weighed, dissolved separately in ethanol, and sonicated for 5 min to mix thoroughly. 2 mL of triethylamine was added to 20 mL of ethanol, and then slowly added dropwise to the above mixed solution under magnetic stirring. The mixture was heated at 75 °C for 2 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature. The solid product was collected by centrifugation, washed three times with anhydrous ethanol, and dried in a vacuum drying oven at 60 °C for 12 hours to obtain activated IRMof-3 powder.

[0031] (2) Preparation of modified solution: Take 40 μL of trifluoroacetic anhydride (TFAA) and disperse it in 20 mL of anhydrous dichloromethane. The volume ratio of trifluoroacetic anhydride (TFAA) to anhydrous dichloromethane is 1:500.

[0032] (3) Hypergravity reaction modification: Weigh 300 mg of the above activated IRMof-3 powder, add it to the modification solution, mix evenly and ultrasonically disperse for 5 minutes to form a uniform suspension; transfer the above suspension to a hypergravity reactor, adjust the rotation speed to 2000 rpm, corresponding to a hypergravity level of 179 g, and react at room temperature for 2 hours.

[0033] (4) Post-processing: After the reaction is completed, the solid product is collected by centrifugation and washed three times with anhydrous dichloromethane to remove unreacted trifluoroacetic anhydride and byproduct trifluoroacetic acid. The product is then dried in a vacuum drying oven at 60 °C for 12 hours to obtain trifluoroacetic anhydride modified IRMOF-3 adsorbent, denoted as IRMOF-3-CF3-40.

[0034] Example 2 (1) Synthesis of IRMOF-3: Activated IRMOF-3 powder was prepared according to the method described in step (1) of Example 1.

[0035] (2) Preparation of modified solution: Take 80 μL of trifluoroacetic anhydride (TFAA) and disperse it in 20 mL of anhydrous dichloromethane. The volume ratio of trifluoroacetic anhydride (TFAA) to anhydrous dichloromethane is 1:250.

[0036] (3) Hypergravity reaction modification: Same as step (3) in Example 1.

[0037] (4) Post-processing: Same as step (4) in Example 1, to obtain trifluoroacetic anhydride modified IRMOF-3 adsorbent, denoted as IRMOF-3-CF3-80.

[0038] Example 3 (1) Synthesis of IRMOF-3: Activated IRMOF-3 powder was prepared according to the method described in step (1) of Example 1.

[0039] (2) Preparation of modified solution: Take 120 μL of trifluoroacetic anhydride (TFAA) and disperse it in 20 mL of anhydrous dichloromethane. The volume ratio of trifluoroacetic anhydride (TFAA) to anhydrous dichloromethane is 1:167.

[0040] (3) Hypergravity reaction modification: Same as step (3) in Example 1.

[0041] (4) Post-treatment: Same as step (4) in Example 1, to obtain trifluoroacetic anhydride modified IRMOF-3 adsorbent, denoted as IRMOF-3-CF3-120.

[0042] Example 4 (1) Synthesis of IRMOF-3: Activated IRMOF-3 powder was prepared according to the method described in step (1) of Example 1.

[0043] (2) Preparation of modified solution: Take 160 μL of trifluoroacetic anhydride (TFAA) and disperse it in 20 mL of anhydrous dichloromethane. The volume ratio of trifluoroacetic anhydride (TFAA) to anhydrous dichloromethane is 1:125.

[0044] (3) Hypergravity reaction modification: Same as step (3) in Example 1.

[0045] (4) Post-processing: Same as step (4) in Example 1, to obtain trifluoroacetic anhydride modified IRMOF-3 adsorbent, denoted as IRMOF-3-CF3-160.

[0046] Comparative Example 2 (1) Synthesis of IRMOF-3: Activated IRMOF-3 powder was prepared according to the method described in step (1) of Example 1.

[0047] (2) Preparation of modified solution: Take 120 μL of trifluoroacetic anhydride (TFAA) and disperse it in 20 mL of anhydrous dichloromethane. The volume ratio of trifluoroacetic anhydride (TFAA) to anhydrous dichloromethane is 1:167.

[0048] (3) Room temperature stirring reaction modification: Transfer the above mixed solution to a sealed bottle and stir magnetically for 24 hours at room temperature.

[0049] (4) Post-treatment: Same as step (4) in Example 1, to obtain the trifluoroacetic anhydride modified IRMOF-3 adsorbent, denoted as IRMOF-3-CF3-120. .

[0050] Performance testing 1. Scanning electron microscope (SEM) image Scanning electron microscope (SEM) images of Examples 1-4 and Comparative Examples 1-2 are shown below. Figure 1 As shown, the original IRMof-3 crystal exhibits a smooth, angular, regular polyhedral morphology. Figure 1 (a) When the amount of TFAA is low, the crystal morphology of the modified material (IRMOF-3-CF3-40 / 80) does not change significantly compared with the original sample. The crystal outline remains intact and the surface is still smooth. This indicates that at this dosage, the modification reaction has little macroscopic effect on the crystal structure. Figure 1(b, c) As the dosage increased, the crystal surface of the IRMOF-3-CF3-120 / 160 sample began to roughen, showing minor signs of etching or deposition, but the overall polyhedral framework and boundaries of the crystal remained clearly maintained, and no large-area collapse occurred. Figure 1 (d, e). This phenomenon suggests that within this dosage range, the modification reaction has significantly acted on the crystal surface, but has not yet shaken the stability of its overall structure. However, when using the conventional stirring method, IRMOF-3-CF3-120 The morphology of the sample underwent a catastrophic change; the crystal structure completely collapsed, transforming into an amorphous, severely aggregated blocky or fragmented morphology, and the original polyhedral features completely disappeared. Figure 1 (f) As reaction time increases, the material undergoes a progressive degradation process from structural preservation to surface modification and finally to bulk hydrolysis and collapse.

[0051] Figure 1 The image in GK is an EDS elemental distribution diagram of IRMof-3-CF3-120 prepared in Example 3. Fluorine (F) is uniformly distributed on the material surface, without obvious local enrichment or deficiency, indicating that trifluoroacetic anhydride was successfully grafted onto the IRMof-3 framework using a centrifugal method.

[0052] 2. Powder X-ray diffraction (XRD) images X-ray diffraction (XRD) analysis was performed on Examples 1-4 and Comparative Examples 1-2. Figure 2 As shown, the XRD patterns of Examples 1-4 are basically consistent with the characteristic peak positions of IRMof-3 in Comparative Example 1, indicating that the rapid modification process under hypergravity did not destroy the crystal framework structure of IRMof-3. The reduced crystallinity in Comparative Example 2 is due to the damage to the crystal structure caused by the trifluoroacetic acid byproduct generated during the long-term reaction.

[0053] 3. Static iodine adsorption performance test The static iodine adsorption capacity of the adsorbent was determined by a gravimetric method. First, the mass of an empty small glass bottle was accurately weighed and recorded as m0. An appropriate amount of trifluoroacetic anhydride-modified IRMOF-3 adsorbent (obtained by gravity method) was placed in the small glass bottle and accurately weighed, recorded as m1 (total mass of the small glass bottle and adsorbent). The small glass bottle containing the adsorbent and excess solid iodine were sealed together in a wide-mouth bottle, ensuring good airtightness. The sealed wide-mouth bottle was placed in a constant-temperature oven at a set temperature for static adsorption. The small glass bottle was removed at regular intervals, cooled to room temperature, and weighed, recorded as m2. This process continued until two consecutive weighings showed no change in mass, indicating adsorption equilibrium had been reached. The saturated iodine adsorption capacity was calculated using the following formula: Q = (m2–m1) / (m1–m0). For wet iodine adsorption, a small glass bottle containing a saturated salt solution was placed inside the sealed wide-mouth bottle to control the relative humidity of the system. Test results ( Figure 3 (a)-(c) in the text show: (1) Under dry conditions: the adsorption capacity of IRMOF-3 was 1.93 g / g, and that of IRMOF-3-CF3-120 was 2.29 g / g, which was 18.7% higher than that of IRMOF-3.

[0054] (2) Water adsorption (18% RH): The water adsorption capacity of IRMOF-3 is 78 mg / g, and that of IRMOF-3-CF3-120 is 42 mg / g, indicating that the introduction of -CF3 significantly reduces the water adsorption capacity.

[0055] (3) Wet iodine vapor (18% RH): The adsorption capacity of IRMOF-3 was 1.36 g / g (a decrease of 29.5%), and that of IRMOF-3-CF3-120 was 1.92 g / g (a decrease of 16.2%), indicating that the fluorinated sample has excellent moisture resistance.

[0056] 4. Cyclic performance test The stability and cyclic regeneration performance of the IRMOF-3-CF3-120 prepared in Example 3 were tested, and the results are as follows: Figure 4 As shown.

[0057] (1) Thermal stability: The thermogravimetric analyzer was used to test the temperature at a rate of 10℃ / min under N2 atmosphere.

[0058] (2) Cyclic performance: The adsorption steps are the same as the humid adsorption method in performance test 3; after adsorption is completed, take out the small glass bottle containing the adsorbent and place it in an oven at 150°C for heat treatment desorption. The desorption time is 6 hours until the mass of the iodine-containing adsorbent no longer changes and the desorption is completed; repeat 5 times.

[0059] Figure 4 (a) shows the XRD patterns before and after the adsorption cycle. After the adsorption-desorption cycle, the characteristic peak positions are consistent with those before adsorption, indicating that the material has good structural stability. The diffraction peak intensities of I2@IRMOF-3-CF3-120 after adsorption are significantly reduced, indicating a decrease in crystallinity. This is because after a large number of iodine molecules enter the MOF channels, they interact strongly with the framework. Iodine molecules accumulate in the channels and occupy the channel space, which disrupts the long-range order of the framework, thus causing a decrease in the intensity of the XRD diffraction peaks.

[0060] Figure 4 (b) shows the TG curves before and after adsorption and desorption. The material did not show significant mass loss below 400℃, but began to decompose above 400℃, indicating good thermal stability.

[0061] Figure 4Figure (c) shows the performance of five adsorption-desorption cycles. The initial adsorption capacity was 1.916 g / g, which decreased to 1.832 g / g after the second cycle (95.6% retention), 1.751 g / g after the third cycle (91.4% retention), 1.658 g / g after the fourth cycle (86.5% retention), and 1.565 g / g after the fifth cycle (81.7% retention). After five cycles, the adsorption capacity retention was greater than 80%, which is still higher than the initial adsorption capacity of unmodified IRMof-3 (1.36 g / g), demonstrating good regeneration performance.

[0062] In summary, the TFAA-modified IRMof-3 adsorbent provided by the present invention exhibits significant advantages in preparation efficiency, structural preservation, and iodine adsorption performance under humid conditions, making it suitable for the efficient capture of radioactive iodine in humid atmospheres in the field of nuclear waste treatment.

[0063] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent using a centrifugal method, characterized in that, Includes the following steps: Step 1: Synthesis of IRMOF-3 crystal material by solvothermal method: Zinc nitrate hexahydrate and 2-aminoterephthalic acid were dissolved in organic solvents and mixed. A mixture of triethylamine and organic solvent was added dropwise and heated to react. After the reaction was completed, the mixture was cooled, centrifuged, and washed with organic solvent. Finally, the product was dried under vacuum to obtain activated IRMOF-3 crystal powder. Step 2: Prepare the modified solution: Add trifluoroacetic anhydride dropwise into anhydrous dichloromethane and mix well to prepare the modified solution; Step 3: Hypergravity reaction modification: The activated IRMof-3 crystal powder obtained in Step 1 is dispersed in the modification solution of Step 2 to form a suspension. The suspension is then placed in a hypergravity reactor for reaction. Under the huge shear force generated by the hypergravity field, the modification solution rapidly penetrates into the pores of IRMof-3, and promotes efficient contact between trifluoroacetic anhydride and the amino functional groups of IRMof-3 and an amidation reaction. Trifluoromethyl hydrophobic groups are grafted onto the pore surface and outer surface of IRMof-3. Step 4: Post-treatment: The reacted material is centrifuged and repeatedly washed with anhydrous dichloromethane to remove unreacted trifluoroacetic anhydride. Finally, it is vacuum dried to obtain the modified IRMOF-3 adsorbent with -CF3 hydrophobic groups grafted onto its surface.

2. The method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent by centrifugal force according to claim 1, characterized in that, The mass ratio of zinc nitrate hexahydrate, 2-aminoterephthalic acid, and triethylamine in step 1 is (0.04~0.06): (0.03~0.04): (1.4~1.6); the organic solvent in step 1 is N,N-dimethylacetamide, N,N-dimethylformamide, ethanol, or methanol.

3. The method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent by centrifugal force according to claim 1, characterized in that, The heating reaction in step 1 is carried out at a temperature of 70-80°C for 1-3 hours.

4. The method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent by centrifugal force according to claim 1, characterized in that, In the modified solution of step 2, the volume ratio of trifluoroacetic anhydride to anhydrous dichloromethane is 1:(500~125).

5. The method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent by centrifugal force according to claim 1, characterized in that, In step 3, the mass ratio of IRMOF-3 crystal powder to the volume ratio of the modified solution in the suspension is 10-20 mg / mL; the hypergravity reactor in step 3 is a rotating packed bed or a high-speed centrifuge, the hypergravity level is controlled at 150-200 g, the reaction temperature is room temperature, and the reaction time is 1-3 hours.

6. The method for preparing trifluoroacetic anhydride-modified IRMOF-3 adsorbent by centrifugal force according to claim 1, characterized in that, The vacuum drying temperature in steps 1 and 4 is 50~70℃, and the time is 10~14 hours.

7. A trifluoroacetic anhydride modified IRMOF-3 adsorbent prepared by any one of claims 1-6 using a supergravity method.

8. The application of a trifluoroacetic anhydride-modified IRMOF-3 adsorbent prepared by any one of claims 1-6 in iodine adsorption, characterized in that, Used to capture gaseous iodine in humid air currents containing water vapor.

9. The application according to claim 8, characterized in that, include: Step 1: Place the trifluoroacetic anhydride modified IRMOF-3 adsorbent for adsorption in a sealed adsorption container; for wet iodine adsorption, place a saturated salt solution in a sealed container to control the relative humidity of the system. Step 2: After adsorption is complete, open the sealed adsorption container and heat to desorb until the mass of the iodine-containing adsorbent no longer changes, at which point desorption is complete.

10. The application according to claim 9, characterized in that, In step 1, the ratio of the amount of trifluoroacetic anhydride-modified IRMOF-3 adsorbent and the amount of iodine adsorbed by the centrifugal method is (50~55) mg: 200 mg; the adsorption temperature is 65~85℃, preferably 80℃; the adsorption time is 1~24h; in step 1, the relative humidity of the adsorption system is controlled to be 18% by adding saturated calcium chloride solution to a sealed container; in step 2, the desorption temperature is 140-160℃.

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