A method of capturing gaseous radioactive iodine and methyl iodide

Abstract

The application discloses a method for capturing gaseous radioactive iodine and methyl iodine, comprising: loading elemental iodine or methyl iodine into a container, loading an adsorbent into another container, placing the two containers in a jar and sealing the jar, and placing the jar in an oven; after a contact time, taking out the jar and cooling to room temperature; determining the static adsorption capacity of the adsorbent by the mass difference before and after the adsorbent, and completing the capture of gaseous iodine and methyl iodine. The application uses full-silicon zeolite nanosheet NSL-1 as an adsorbent, which is a kind of zeolite molecular sieve material, has a nanosheet shape, a rich pore structure, high hydrophobicity, thermal stability and acid stability, and thus effectively captures gaseous iodine and methyl iodine. The adsorbent has a simple preparation method, can be mass-produced, is easy to regenerate, can be reused, and saves cost. In addition, even under humid conditions and after nitrogen oxide treatment, the full-silicon zeolite nanosheet NSL-1 still maintains good capture capacity, and the adsorption capacity is much higher than that of commercial mordenite.

Description

Technical Field

[0001] This invention belongs to the field of radioactive gas processing technology, and more specifically, this invention relates to a method for capturing gaseous radioactive iodine and methyl iodine. Background Technology

[0002] Nuclear energy, as a sustainable and low-carbon energy source, is expected to play a more important role in the future. However, safety issues still pose challenges to its operation. One major safety concern is the volatile radioactive waste generated during spent fuel reprocessing, particularly radionuclides. 129 I and 131 I exists primarily as molecular iodine (I2) and organic iodides (such as methyl iodine and ethyl iodine). 129 I has a very long half-life, approximately 1.57 × 10⁻⁶. 7 Year, 131 Iodine has a high specific activity and a short half-life of about 8 days. These iodine isotopes pose a serious threat to the environment or severely affect human metabolism by damaging the thyroid gland, and must be removed before being emitted into waste gases.

[0003] Compared to traditional wet scrubbing processes for capturing radioactive iodine, solid-state adsorption methods require simpler operation, lower maintenance costs, and avoidance of highly corrosive solutions. Therefore, the development of various iodine-capturing adsorbents has attracted increasing attention, including silver-based materials, bismuth-based materials, zeolites, aerogels, metal-organic frameworks, and covalent organic polymers. Most of these studies focus on I2 adsorption capacity, with only a few addressing CH3I capture. Given the coexistence of radioactive molecular iodine and organic iodides in the waste gas stream, developing adsorbents capable of simultaneously and effectively capturing them is particularly important. Furthermore, in addition to volatile iodine, the waste gas generated during spent fuel reprocessing also contains large amounts of water vapor and nitrogen oxides. Maintaining the stability of the adsorbent and its good adsorption performance under nitrogen oxide and high humidity conditions is also a significant challenge. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] In order to achieve these objectives and other advantages according to the present invention, an application of all-silica zeolite nanosheets NSL-1 is provided, which are used to capture gaseous radioactive iodine and methyl iodine.

[0006] A method for capturing gaseous radioactive iodine and methyl iodine includes:

[0007] Weigh out elemental iodine or methyl iodine and place it in a container. Then, place the adsorbent in another container. Put the two containers in a wide-mouth bottle and seal it. Place the bottle in an oven. After a period of contact, remove the bottle and cool it to room temperature. Determine the static adsorption capacity of the adsorbent by the mass difference before and after the process. The collection of gaseous iodine and methyl iodine is completed. The adsorbent is NSL-1 all-silica zeolite nanosheets.

[0008] Preferably, the mass ratio of elemental iodine or methyl iodine to the adsorbent is 1:5 to 10.

[0009] Preferably, the temperature of the oven is 60–80°C.

[0010] Preferably, the static adsorption capacity of the adsorbent is obtained by weighing to determine the mass of the adsorbent before and after the adsorption.

[0011] Preferably, the preparation method of the all-silica zeolite nanosheets NSL-1 includes: dissolving tetraethyl orthosilicate and tetrapropylammonium hydroxide in water, stirring, adding an aqueous solution of ammonium fluoride and continuing to stir, then transferring it to a reaction vessel and reacting at a certain temperature, filtering the white product, and calcining to obtain all-silica zeolite nanosheets NSL-1.

[0012] Preferably, the molar ratio of tetraethyl orthosilicate, tetrapropylammonium hydroxide, water and ammonium fluoride is 1:y:110:x, where x = 0 to 1.4 and y = 0.05 to 0.2.

[0013] Preferably, after dissolving tetraethyl orthosilicate and tetrapropylammonium hydroxide in water, the stirring temperature is 60–90°C and the stirring time is 12–36 h; the reaction temperature after transferring to the reactor is 100–140°C and the reaction time is 80–120 h; the calcination temperature is 400–600°C.

[0014] Preferably, the all-silica zeolite nanosheets NSL-1 are first subjected to NO treatment before capturing gaseous radioactive iodine and methyl iodine. X The treatment method includes: exposing all-silica zeolite nanosheets NSL-1 to NO. X In a closed gas-filled device, NSL-1 all-silica zeolite nanosheets are reacted with NO. X The gases were in full contact for 24 hours; among them, NO X The gas is generated by the reaction of Cu and concentrated nitric acid, specifically by exposing all-silica zeolite nanosheets NSL-1 to a generator containing a mixture of Cu powder and excess concentrated nitric acid, in which NO is generated. X The mass fraction of the gas is 0-20%, and the corresponding mass-to-volume ratio of Cu powder and excess concentrated nitric acid is 145.3-581.2 mg: 2-4 mL, with the concentrated nitric acid having a mass fraction of 65%.

[0015] Preferably, before the all-silica zeolite nanosheets NSL-1 capture gaseous radioactive iodine and methyl iodine under certain humidity conditions, the containers containing elemental iodine or methyl iodine and the container containing all-silica zeolite nanosheets NSL-1 are placed into a wide-mouth bottle, and at the same time, a container filled with a saturated halide salt aqueous solution is placed in the wide-mouth bottle. The containers containing all-silica zeolite nanosheets NSL-1, elemental iodine or methyl iodine, and halide salt aqueous solution have the same volume, and the saturated halide salt aqueous solution includes saturated magnesium chloride aqueous solution, saturated sodium bromide aqueous solution, saturated sodium chloride aqueous solution, and saturated potassium chloride aqueous solution.

[0016] To improve the adsorption capacity of all-silica zeolite nanosheets NSL-1 for gaseous radioactive iodine and methyl iodine, the all-silica zeolite nanosheets NSL-1 were modified to obtain modified all-silica zeolite nanosheets NSL-1. The preparation method of modified all-silica zeolite nanosheets NSL-1 includes:

[0017] Step 1: Add aluminum chloride solution and urea to sodium hydroxide solution, stir for 20-60 minutes and let stand; then transfer to high pressure reactor, add acetamide, pressurize and react for 1-3 hours. After the reaction is completed, separate solid and liquid, dry and disperse in 10%-25% polyethylene glycol-400 solution, filter to obtain layered aluminum hydroxide particles.

[0018] Step 2: Mix the calcined all-silica zeolite nanosheets NSL-1 with the layered aluminum hydroxide particles obtained in Step 1 to obtain mixed solid particles, wherein the mass ratio of all-silica zeolite nanosheets NSL-1 to layered aluminum hydroxide powder is 50:1-3; load copper onto the mixed solid particles to obtain modified all-silica zeolite nanosheets NSL-1. The loading method includes: immersing the mixed powder in Cu(NO3)2 solution, ultrasonically vibrating, then adding polyethyleneimine, continuing to add NaOH solution dropwise and stirring for 20-50 min to adjust the pH to 8-10 to obtain a mixed solution; placing the mixed solution in a constant temperature water bath at 30-50℃ for 30-80 min, adding hydrazine hydrate dropwise to the mixed solution, and stirring slowly to allow the reduced Cu to be loaded onto the mixed solid particles; filtering and drying to obtain modified all-silica zeolite nanosheets NSL-1.

[0019] In step one, the concentration of aluminum chloride solution is 0.2–1 mol / L, the concentration of sodium hydroxide is 0.5–3 mol / L, and the volume-to-mass ratio of aluminum chloride solution, urea, sodium hydroxide, acetamide, and polyethylene glycol-400 is 5–12 mL: 0.2–1 mL: 8–20 mL: 2–7 mg: 150–400 mL; the applied pressure is 1.2 × 10⁻⁶. 4 ~2.5×10 4 kPa;

[0020] In step two, the concentration of Cu(NO3)2 solution is 0.003-0.05 mol / L, and the mass-volume ratio of all-silica zeolite nanosheets NSL-1, Cu(NO3)2 solution, polyethyleneimine, and hydrazine hydrate is 50 mg: 30-250 mL: 10-30 mg: 15-80 mg.

[0021] The present invention offers at least the following advantages: The method for capturing gaseous radioactive iodine and methyl iodine disclosed herein utilizes all-silica zeolite nanosheets NSL-1 as an adsorbent. NSL-1 is an example of a zeolite molecular sieve material, exhibiting a nanosheet structure with abundant pores, high hydrophobicity, thermal stability, and acid stability, thereby effectively capturing gaseous iodine and methyl iodine. The adsorbent is simple to prepare, can be mass-produced, is easily regenerated, and can be reused, saving costs. Furthermore, the method of the present invention maintains good capture capacity even under humid conditions and after treatment with nitrogen oxides, with an adsorption capacity far exceeding that of commercial mordenite zeolite.

[0022] Meanwhile, this invention uses aluminum chloride, urea, sodium hydroxide and acetamide to prepare layered aluminum hydroxide. All-silica zeolite nanosheets NSL-1 and layered aluminum oxide are mixed at a mass ratio of 50:1 to 3 to obtain mixed solid particles with a certain silicon-aluminum ratio. Then, elemental copper is deposited on the surface of the mixed solid particles, which increases the adsorption surface area of ​​the modified all-silica zeolite nanosheets NSL-1 and further improves the adsorption capacity for radioactive gaseous iodine and methyl iodine.

[0023] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0024] Figure 1 This is an adsorption kinetic diagram of gaseous iodine capture in Example 1 of the present invention;

[0025] Figure 2 This is an adsorption kinetic diagram of methyl iodine capture in Example 2 of the present invention;

[0026] Figure 3 This is a graph showing the adsorption amount of gaseous iodine captured under different humidity conditions in Examples 3-7 of the present invention;

[0027] Figure 4 The graphs show the adsorption amounts of gaseous iodine captured after treatment with different concentrations of nitrogen oxides in Examples 8-11 of the present invention.

[0028] Figure 5 This is an adsorption kinetic diagram of gaseous iodine capture in Example 12 of the present invention;

[0029] Figure 6 This is an adsorption kinetic diagram of methyl iodine capture in Example 13 of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0031] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0032] Example 1:

[0033] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0034] Nine 30mg portions of all-silica zeolite nanosheets (NSL-1) were weighed and placed into nine 5mL glass vials. Then, 3g of iodine was weighed and placed into another nine 5mL glass vials. Two vials (all-silica zeolite nanosheets NSL-1 + iodine) were placed in a 100mL wide-mouth bottle and sealed. A total of nine groups were placed in a 75℃ oven. After drying for 10, 20, 30, 45, 60, 90, 120, 180, and 240 minutes respectively... Take out a wide-mouth bottle and cool it to room temperature; repeat the process 3 times. The static adsorption capacity is determined by the mass difference of the adsorbent before and after the process. The adsorption capacity of all-silica zeolite nanosheets NSL-1 for gaseous iodine at different contact times is calculated to be 310±42mg / g, 432±28mg / g, 502±30mg / g, 553±35mg / g, 532±26mg / g, 548±33mg / g, 559±31mg / g, 555±44mg / g, and 562±38mg / g, respectively.

[0035] The preparation method of all-silica zeolite nanosheets NSL-1 includes: dissolving 1 mol of tetraethyl orthosilicate and 0.1 mol of tetrapropylammonium hydroxide in 110 mol of water, stirring at 90°C for 24 h, adding 0.12 mol of ammonium fluoride aqueous solution and stirring for another 24 h, then transferring to a reaction vessel and reacting at 120°C for 96 h, filtering the white product, and calcining at 550°C to obtain all-silica zeolite nanosheets NSL-1.

[0036] Example 2:

[0037] This embodiment provides a method for capturing gaseous methyl iodine, including:

[0038] Nine 30mg portions of all-silica zeolite nanosheets NSL-1 were weighed and placed into nine 5mL glass vials. Then, 3g of methyl iodine was weighed and placed into another nine 5mL glass vials. Two vials (all-silica zeolite nanosheets NSL-1 + methyl iodine) were placed in a 100mL wide-mouth bottle and sealed. A total of nine groups were placed in a 75℃ oven. The ovens were then heated at 10min, 20min, 30min, 45min, 60min, 90min, 120min, 180min, and 240min. After n, a wide-mouth bottle was taken out and cooled to room temperature; the process was repeated 3 times, and the static adsorption capacity was determined by the mass difference of the adsorbent before and after. The adsorption capacity of all-silica zeolite nanosheets NSL-1 for methyl iodine at different contact times was calculated to be 115±30mg / g, 156±20mg / g, 175±33mg / g, 222±18mg / g, 262±27mg / g, 255±30mg / g, 264±16mg / g, 248±27mg / g, and 256±33mg / g, respectively.

[0039] Example 3:

[0040] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0041] 30 mg of all-silica zeolite nanosheets NSL-1 and 30 mg of commercial mordenite zeolite MOR were weighed and placed into two 5 mL glass vials. Then, 3 g of iodine was weighed and placed into another 5 mL glass vial. The three glass vials were placed in a 100 mL wide-mouth bottle and sealed with a cap. The bottle was placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. The process was repeated three times. The static adsorption capacity was determined by the mass difference of the adsorbent before and after the process. The adsorption capacity of all-silica zeolite nanosheets NSL-1 and mordenite zeolite MOR for gaseous iodine was calculated to be 556 ± 14 mg / g and 132 ± 20 mg / g, respectively.

[0042] Example 4:

[0043] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0044] 30 mg of all-silica zeolite nanosheets NSL-1 and 30 mg of commercial mordenite zeolite MOR were weighed and placed into two 5 mL glass vials. 3 g of iodine was weighed and placed into one 5 mL glass vial. 5 mL of saturated magnesium chloride aqueous solution (27% RH) was placed into one 5 mL glass vial. The four glass vials were placed in a 100 mL wide-mouth bottle and sealed. The vials were placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. This process was repeated three times. The static adsorption capacity was determined by the difference in mass of the adsorbent before and after the process. The adsorption capacities of all-silica zeolite nanosheets NSL-1 and mordenite zeolite MOR for gaseous iodine were calculated to be 531 ± 33 mg / g and 23 ± 9 mg / g, respectively.

[0045] Example 5:

[0046] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0047] 30 mg of all-silica zeolite nanosheets NSL-1 and 30 mg of commercial mordenite MOR were weighed and placed into two 5 mL glass vials, respectively. 3 g of iodine was weighed and placed into one 5 mL glass vial. 5 mL of saturated sodium bromide aqueous solution (50% RH) was placed into one 5 mL glass vial. The four vials were placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. This process was repeated three times. The static adsorption capacity was determined by the difference in mass of the adsorbent before and after the process. The adsorption capacities of all-silica zeolite nanosheets NSL-1 and mordenite MOR for gaseous iodine were calculated to be 547 ± 28 mg / g and 28 ± 17 mg / g, respectively.

[0048] Example 6:

[0049] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0050] 30 mg of all-silica zeolite nanosheets NSL-1 and 30 mg of commercial mordenite MOR were weighed and placed into two 5 mL glass vials, respectively. 3 g of iodine was weighed and placed into one 5 mL glass vial. 5 mL of saturated sodium chloride aqueous solution (75% RH) was placed into one 5 mL glass vial. The four vials were placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. This process was repeated three times. The static adsorption capacity was determined by the difference in mass of the adsorbent before and after the process. The adsorption capacities of all-silica zeolite nanosheets NSL-1 and mordenite MOR for gaseous iodine were calculated to be 530 ± 46 mg / g and 12 ± 5 mg / g, respectively.

[0051] Example 7:

[0052] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0053] 30 mg of all-silica zeolite nanosheets NSL-1 and 30 mg of commercial mordenite MOR were weighed and placed into two 5 mL glass vials, respectively. 3 g of iodine was weighed and placed into one 5 mL glass vial. 5 mL of saturated potassium chloride aqueous solution (80% RH) was placed into one 5 mL glass vial. The four vials were placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. This process was repeated three times. The static adsorption capacity was determined by the difference in mass of the adsorbent before and after the process. The adsorption capacities of all-silica zeolite nanosheets NSL-1 and mordenite MOR for gaseous iodine were calculated to be 543 ± 35 mg / g and 28 ± 10 mg / g, respectively.

[0054] Example 8:

[0055] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0056] 30 mg each of NSL-1 all-silica zeolite nanosheets, CSL-1 commercial all-silica zeolite, MOR commercial mordenite, and NaY commercial octahedral zeolite were weighed and placed into four 5 mL glass vials. 3 g of iodine was weighed and placed into one 5 mL glass vial. The five vials were placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. The static adsorption capacity was determined by the mass difference of the adsorbent before and after the process. The adsorption capacities of NSL-1 all-silica zeolite nanosheets, CSL-1 commercial all-silica zeolite, MOR mordenite, and NaY octahedral zeolite for gaseous iodine were calculated to be 537 mg / g, 454 mg / g, 144 mg / g, and 24 mg / g, respectively.

[0057] Example 9:

[0058] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0059] Weigh out 5% NO respectively X After 24 hours of treatment, 30 mg each of all-silica zeolite nanosheets NSL-1, commercial all-silica zeolite CSL-1, commercial mordenite MOR, and commercial octahedral zeolite NaY were placed in four 5 mL glass vials. 3 g of iodine was weighed and placed in one 5 mL glass vial. The five vials were placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75 °C oven. After 60 min, the wide-mouth bottle was removed and cooled to room temperature. The static adsorption capacity was determined by the mass difference of the adsorbent before and after treatment. The adsorption capacities of all-silica zeolite nanosheets NSL-1, commercial all-silica zeolite CSL-1, mordenite MOR, and octahedral zeolite NaY for gaseous iodine were calculated to be 500 mg / g, 420 mg / g, 55 mg / g, and 48 mg / g, respectively.

[0060] Among them, NO X The method for processing all-silica zeolite nanosheets NSL-1 includes: weighing 145.3 mg of copper powder and 2 ml of concentrated nitric acid (65% by mass) and reacting them in a 2800 ml sealed container; simultaneously, placing 30 mg of all-silica zeolite nanosheets NSL-1 into the sealed container; and allowing the all-silica zeolite nanosheets NSL-1 to react with NO in the sealed container. X Full contact, with an exposure time of 24 hours.

[0061] Example 10:

[0062] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0063] Weigh out 10% NO respectively X After 24 hours of treatment, 30 mg each of all-silica zeolite nanosheets NSL-1, commercial all-silica zeolite CSL-1, commercial mordenite MOR, and commercial octahedral zeolite NaY were placed in four 5 mL glass vials. 3 g of iodine was weighed and placed in one 5 mL glass vial. The five vials were then placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75°C oven. After 60 minutes, the wide-mouth bottle was removed and cooled to room temperature. The static adsorption capacity was determined by the mass difference of the adsorbent before and after treatment. The adsorption capacities of all-silica zeolite nanosheets NSL-1, commercial all-silica zeolite CSL-1, mordenite MOR, and octahedral zeolite NaY for gaseous iodine were calculated to be 435 mg / g, 360 mg / g, 0 mg / g, and 0 mg / g, respectively. Among these, NO... X The method for processing all-silica zeolite nanosheets NSL-1 is the same as in Example 9, except that the amount of copper powder used in the sealed device is 290.6 mg and the amount of concentrated nitric acid is 3 ml.

[0064] Example 11:

[0065] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0066] Weigh out 20% NO respectively XAfter 24 hours of treatment, 30 mg each of all-silica zeolite nanosheets NSL-1, commercial all-silica zeolite CSL-1, commercial mordenite MOR, and commercial octahedral zeolite NaY were placed in four 5 mL glass vials. 3 g of iodine was weighed and placed in one 5 mL glass vial. The five vials were then placed in a 100 mL wide-mouth bottle, sealed, and placed in a 75 °C oven. After 60 minutes, the wide-mouth bottle was removed and cooled to room temperature. The static adsorption capacity was determined by the mass difference of the adsorbent before and after treatment. The adsorption capacities of all-silica zeolite nanosheets NSL-1, commercial all-silica zeolite CSL-1, mordenite MOR, and octahedral zeolite NaY for gaseous iodine were calculated to be 457 mg / g, 2922 mg / g, 0 mg / g, and 0 mg / g, respectively. Among these, NO... X The method for processing all-silica zeolite nanosheets NSL-1 is the same as in Example 9, except that the amount of copper powder used in the sealed device is 581.2 mg and the amount of concentrated nitric acid is 4 mL.

[0067] Example 12:

[0068] This embodiment provides a method for capturing gaseous radioactive iodine, including:

[0069] Nine 30mg portions of modified all-silica zeolite nanosheets NSL-1 were weighed and placed into nine 5mL glass vials. Then, 3g of iodine was weighed and placed into another nine 5mL glass vials. Two vials (all-silica zeolite nanosheets NSL-1 + iodine) were placed in a 100mL wide-mouth bottle and sealed. A total of nine groups were placed in a 75℃ oven and dried for 10, 20, 30, 45, 60, 90, 120, 180, and 240 minutes. Then, a wide-mouth bottle was taken out and cooled to room temperature; the process was repeated 3 times, and the static adsorption capacity was determined by the mass difference of the adsorbent before and after. The adsorption capacity of all-silica zeolite nanosheets NSL-1 for gaseous iodine at different contact times was calculated to be 324±29 mg / g, 457±24 mg / g, 529±31 mg / g, 568±32 mg / g, 562±22 mg / g, 565±28 mg / g, 572±35 mg / g, 578±32 mg / g, and 580±26 mg / g, respectively.

[0070] The preparation method of modified all-silica zeolite nanosheets NSL-1 includes:

[0071] Step 1: Add 100 mL of 0.5 mol / L aluminum chloride solution and 10 mL of urea to 150 mL of 1 mol / L sodium hydroxide solution, stir for 30 min, and let stand; then transfer to an autoclave, add 25 mg of acetamide, and pressurize to 2.2 × 10⁻⁶. 4kPa, react for 2 hours, after the reaction is completed, the solid and liquid are separated, and after drying, the solid pulverized material is dispersed in 2500 mL of polyethylene glycol-400 solution with a mass fraction of 10% to 25%, and filtered to obtain layered aluminum hydroxide particles;

[0072] Step 2: Mix 500 mg of the all-silica zeolite nanosheets NSL-1 obtained from calcination in Example 1 with 20 mg of layered aluminum hydroxide particles obtained in Step 1 to obtain mixed solid particles; load copper onto the mixed solid particles to obtain modified all-silica zeolite nanosheets NSL-1. The loading method includes: immersing the mixed powder in 2000 mL of 0.05 mol / L Cu(NO3)2 solution, ultrasonically vibrating, then adding 150 mg of polyethyleneimine, adding NaOH solution dropwise and stirring for 30 min to adjust the pH to 8 to obtain a mixed solution; placing the mixed solution in a constant temperature water bath and maintaining the temperature at 40°C for 50 min, adding 200 mg of hydrazine hydrate dropwise to the mixed solution, and stirring slowly to load the reduced Cu onto the mixed solid particles; filtering and drying to obtain modified all-silica zeolite nanosheets NSL-1.

[0073] Example 13

[0074] This embodiment provides a method for capturing gaseous methyl iodine, including:

[0075] Nine 30 mg portions of modified all-silica zeolite nanosheets NSL-1 were weighed and placed into nine 5 mL glass vials. The preparation method of modified all-silica zeolite nanosheets NSL-1 was the same as in Example 12. Then, 3 g of methyl iodine was weighed and placed into another nine 5 mL glass vials. Two vials (all-silica zeolite nanosheets NSL-1 + methyl iodine) were placed in a 100 mL wide-mouth bottle and sealed. A total of nine groups were placed in a 75 °C oven. The ovens were heated at 10 min, 20 min, 30 min, 45 min, 60 min, 90 min, and 120 °C. After 1 min, 180 min, and 240 min, a wide-mouth bottle was removed and cooled to room temperature. This was repeated 3 times. The static adsorption capacity was determined by the mass difference of the adsorbent before and after the reaction. The adsorption capacity of all-silica zeolite nanosheets NSL-1 for methyl iodine at different contact times was calculated to be 138±24 mg / g, 176±25 mg / g, 196±28 mg / g, 247±15 mg / g, 288±32 mg / g, 296±27 mg / g, 301±19 mg / g, 290±24 mg / g, and 298±32 mg / g, respectively.

[0076] Figure 1 This is the adsorption kinetics diagram for capturing gaseous iodine in Example 1. From... Figure 1It can be seen that the adsorption of I2 by the all-silica zeolite nanosheets NSL-1 gradually increases with the increase of contact time. The all-silica zeolite nanosheets NSL-1 can reach equilibrium within 45 min, and the maximum adsorption capacity is 553±35 mg / g.

[0077] Figure 2 This is the adsorption kinetics diagram for the capture of methyl iodine in Example 2. From... Figure 2 It can be seen that the adsorption of CH3I by the all-silica zeolite nanosheets NSL-1 gradually increases with increasing contact time. The adsorbent can reach equilibrium within 60 min, and the maximum adsorption capacity is 262±27 mg / g.

[0078] Figure 3 This is a graph showing the adsorption amount of gaseous iodine captured under different humidity conditions in Examples 3-7. Figure 3 In the text, NSL-1 indicates the use of all-silica zeolite nanosheets (NSL-1) to adsorb gaseous iodine, while MOR indicates the use of commercially available mordenite zeolite (MOR) to adsorb gaseous iodine. Data analysis shows that under different humidity conditions (dry, 27% RH, 50% RH, 75% RH, 80% RH), the all-silica zeolite nanosheets (NSL-1) have a higher capacity for capturing gaseous iodine than the commercially available mordenite zeolite (MOR), highlighting the intrinsic hydrophobicity of all-silica zeolite.

[0079] Figure 4 This is a graph showing the adsorption capacity of gaseous iodine after treatment with different concentrations of nitrogen oxides in Examples 8-11. Figure 4 In the text, NSL-1 indicates the use of all-silica zeolite nanosheets (NSL-1) to adsorb gaseous iodine, CSL-1 indicates the use of commercially available all-silica zeolite (CSL-1) to adsorb gaseous iodine, MOR indicates the use of commercially available mordenite (MOR) to adsorb gaseous iodine, and NaY indicates the use of commercially available octahedral zeolite (NaY) to adsorb gaseous iodine. Data analysis was conducted to determine the adsorption of gaseous iodine using different concentrations of nitrogen oxides (0%, 5%, 10%, 20%). X After treatment, the ability of NSL-1 all-silica zeolite nanosheets to capture gaseous iodine is higher than that of commercial all-silica zeolite CSL-1, mordenite MOR and octahedral zeolite NaY, and it has good antioxidant properties and acid stability.

[0080] Figure 5 This is an adsorption kinetic diagram of gaseous iodine captured by the modified all-silica zeolite nanosheets NSL-1 prepared in Example 12. Figure 6 The adsorption kinetics diagram for methyl iodine capture by the modified all-silica zeolite nanosheets NSL-1 prepared in Example 13 is shown below. Figure 5 and Figure 6 As can be seen, compared with Example 1, the modified all-silica zeolite nanosheets NSL-1 mixed with layered aluminum hydroxide and loaded with copper in Examples 12 and 13 have better adsorption effects on gaseous iodine and methyl iodine.

[0081] In the above-mentioned method for capturing gaseous radioactive iodine and methyl iodine, all-silica zeolite is used as the adsorbent. After the addition of ammonium fluoride, the zeolite structure becomes nanosheet-like, possessing abundant pores, high hydrophobicity, and nitrogen oxide stability, thus effectively capturing gaseous iodine and methyl iodine. The preparation method of all-silica zeolite nanosheets NSL-1 is simple, can be mass-produced, is easily regenerated, and can be reused, saving costs. Furthermore, the method of this invention maintains good capturing ability even under humid conditions and after nitrogen oxide treatment, with an adsorption capacity far exceeding that of commercial mordenite zeolite.

[0082] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0083] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for capturing gaseous radioactive iodine and methyl iodine, characterized in that, The adsorbent used to capture gaseous radioactive iodine and methyl iodine is modified all-silica zeolite nanosheets NSL-1; The method for capturing gaseous radioactive iodine and methyl iodine using the modified all-silica zeolite nanosheets NSL-1 includes: Weigh out elemental iodine or methyl iodine and put it into a container. Then put the adsorbent into another container. Place the two containers into a wide-mouth bottle and seal it. Place the bottle in an oven. After a period of contact, remove the bottle and cool it to room temperature. Determine the static adsorption capacity of the adsorbent by the mass difference before and after the process. This completes the capture of gaseous iodine and methyl iodine. The preparation methods of modified all-silica zeolite nanosheets NSL-1 include: Step 1: Add aluminum chloride solution and urea to sodium hydroxide solution, stir for 20-60 minutes and let stand; then transfer to high pressure reactor, add acetamide, pressurize and react for 1-3 hours. After the reaction is completed, separate solid and liquid, dry and disperse in 10%-25% polyethylene glycol-400 solution, filter to obtain layered aluminum hydroxide particles. Step 2: Mix the calcined all-silica zeolite nanosheets NSL-1 with the layered aluminum hydroxide particles obtained in Step 1 to obtain mixed solid particles, wherein the mass ratio of all-silica zeolite nanosheets NSL-1 to layered aluminum hydroxide powder is 50:1~3; load copper onto the mixed solid particles to obtain modified all-silica zeolite nanosheets NSL-1. The loading method includes: immersing the mixed powder in Cu(NO3)2 solution, ultrasonically vibrating, then adding polyethyleneimine, continuing to add NaOH solution dropwise and stirring for 20~50 min to adjust the pH to 8~10 to obtain a mixed solution; placing the mixed solution in a constant temperature water bath at 30~50℃ for 30~80 min, adding hydrazine hydrate dropwise to the mixed solution, stirring slowly, so that the reduced Cu is loaded onto the mixed solid particles, filtering and drying to obtain modified all-silica zeolite nanosheets NSL-1.

2. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 1, characterized in that, The mass ratio of elemental iodine or methyl iodine to the adsorbent is 1:5~10.

3. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 1, characterized in that, The oven temperature is 60~80℃.

4. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 1, characterized in that, The static adsorption capacity of the adsorbent was obtained by weighing to determine the mass of the adsorbent before and after the adsorption.

5. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 1, characterized in that, The preparation method of the all-silica zeolite nanosheets NSL-1 includes: dissolving tetraethyl orthosilicate and tetrapropylammonium hydroxide in water, stirring, adding ammonium fluoride aqueous solution and continuing to stir, then transferring to a reaction vessel and reacting at a certain temperature, filtering the white product, and calcining to obtain all-silica zeolite nanosheets NSL-1.

6. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 5, characterized in that, The molar ratio of tetraethyl orthosilicate, tetrapropylammonium hydroxide, water and ammonium fluoride is 1 : y : 110 : x, where x = 0~1.4 and y = 0.05~0.

2.

7. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 5, characterized in that, After dissolving tetraethyl orthosilicate and tetrapropylammonium hydroxide in water, the stirring temperature is 60~90℃ and the stirring time is 12~36h; after transferring to the reaction vessel, the reaction temperature is 100~140℃ and the reaction time is 80~120h; the calcination temperature is 400~600℃.

8. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 1, characterized in that, The modified all-silica zeolite nanosheets NSL-1 are first subjected to NO before capturing gaseous radioactive iodine and methyl iodine. X The treatment method includes: exposing modified all-silica zeolite nanosheets NSL-1 to NO. X In a closed gas-filled device, modified all-silica zeolite nanosheets NSL-1 were reacted with NO. X The gases were in full contact for 24 hours; among them, NO X The gas is generated by the reaction of Cu and concentrated nitric acid, specifically by exposing modified all-silica zeolite nanosheets NSL-1 to a generator containing a mixture of Cu powder and excess concentrated nitric acid, in which NO is generated. X The mass fraction of the gas is 0~20%, and the corresponding mass-to-volume ratio of Cu powder and excess concentrated nitric acid is 145.3~581.2 mg : 2~4 mL, with the mass fraction of concentrated nitric acid being 65%.

9. The method for capturing gaseous radioactive iodine and methyl iodine as described in claim 1, characterized in that, Before the modified all-silica zeolite nanosheets NSL-1 capture gaseous radioactive iodine and methyl iodine under certain humidity conditions, a container containing elemental iodine or methyl iodine and a container containing modified all-silica zeolite nanosheets NSL-1 are placed into a wide-mouth bottle. At the same time, a container filled with a saturated halide salt aqueous solution is placed in the wide-mouth bottle. The containers containing modified all-silica zeolite nanosheets NSL-1, elemental iodine or methyl iodine, and halide salt aqueous solution have the same volume. The saturated halide salt aqueous solution includes saturated magnesium chloride aqueous solution, saturated sodium bromide aqueous solution, saturated sodium chloride aqueous solution, or saturated potassium chloride aqueous solution.

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