Multi-scale radon gas adsorption material and preparation method thereof

Abstract

The invention provides a multi-scale radon gas adsorption material and a preparation method thereof.According to the multi-scale radon gas adsorption material and the preparation method thereof, benzyl dichloride serves as a monomer, anhydrous FeCl3 serves as a catalyst, 1, 2-dichloroethane serves as a dispersion phase solvent, organic silicon or alkane serves as a continuous phase, activated carbon and the continuous phase are evenly mixed, a solvothermal method is combined, and one-pot large-scale preparation of AC / TCN / MOF is achieved; the constructed'activated carbon-tubular carbon nanofiber-metal organic framework 'material has an accurate hierarchical porous structure, the micropore diameter of the multi-scale radon gas adsorption material prepared by the method is 0.35-0.44 nm, and the problem that the interaction force between the activated carbon material and target gas is relatively weak is solved.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials technology, and in particular to a multi-scale radon adsorption material and its preparation method. Background Technology

[0002] Radon (Rn-222) is a naturally occurring radioactive gas that decays from elements such as uranium and radium. It is colorless and odorless, and long-term inhalation increases the risk of lung cancer, especially in high-radon environments such as uranium mines, basements, and densely populated areas, requiring focused control. Porous material adsorption is a common separation and purification technique that utilizes the unique structure and surface properties of porous materials to separate target substances from mixtures. This method is widely used in chemistry, biology, and environmental fields, offering advantages such as high efficiency, simplicity, and environmental friendliness.

[0003] Activated carbon, with its well-developed microporous structure, large specific surface area, acid and alkali resistance, radiation resistance, and low cost, is an important adsorbent material for radioactive gas treatment. When radioactive gas migrates to the surface of activated carbon, it is rapidly adsorbed, reducing the concentration of the surrounding radioactive gas. Under the influence of the concentration gradient, the high concentration of radioactive gas continues to diffuse into the unsaturated activated carbon until the gas adsorption reaches its maximum value and reaches equilibrium with the surrounding gas concentration.

[0004] Currently, activated carbon radon reduction technology suffers from limitations. Due to the wide micropore size distribution of activated carbon (0-2 nm), it cannot precisely match the kinetic diameter of radon (0.417 nm), resulting in only weak van der Waals interactions between activated carbon and the gas, and the adsorption performance needs further improvement.

[0005] The above problems urgently need to be addressed. Summary of the Invention

[0006] This invention discloses a multi-scale radon adsorption material, its preparation method, and its application, aiming to solve the technical problems existing in the prior art.

[0007] The present invention adopts the following technical solution: According to a first aspect of the present invention, the present invention provides a method for preparing a multi-scale radon adsorbent material, the method comprising the following steps: The preparation of activated carbon / tubular polymer nanofibers involves dissolving monomers in a dispersant to form a dispersion solution, mixing activated carbon and polydimethylsiloxane to form a mixed solution, adding the dispersion solution to the mixed solution, and then adding a catalyst solution. The reaction is carried out at 60-100℃ for 6-10 h. After filtration and washing, a solid is obtained. The solid is then subjected to Soxhlet extraction and vacuum drying to obtain activated carbon / tubular polymer nanofibers. Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined under vacuum and cooled to room temperature to obtain activated carbon / tubular carbon nanofibers. Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular carbon nanofibers are added to an oxidant for reaction, cooled to room temperature, washed and dried to obtain carboxyl-modified activated carbon / tubular carbon nanofibers. Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite material: The obtained carboxyl-modified activated carbon / tubular carbon nanofiber was dispersed in an organic solvent, Zn(NO3)2·6H2O was added, and then 2-methylimidazole solution was added and stirred evenly. After centrifugation, the precipitate was collected and washed to obtain multi-scale adsorption material.

[0008] In one possible implementation, the monomer includes any one of p-dichlorobenzyl, m-dichlorobenzyl, or o-dichlorobenzyl.

[0009] In one possible implementation, the dispersant comprises any one of 1,2-dichloroethane, n-hexane, cyclohexane, and n-heptane, and the ratio of the catalyst to the monomer is 1.6:1.

[0010] In one possible implementation, the catalyst solution is prepared by dissolving the catalyst in a 1,2-dichloroethane solution, wherein the catalyst is anhydrous FeCl3, and the concentration of the catalyst in the catalyst solution is 75 mg / mL; the filtration is followed by washing with 1,2-dichloroethane and anhydrous ethanol.

[0011] In one possible implementation, the activated carbon / tubular polymer nanofibers are calcined under vacuum at a temperature of 600-700°C for 5 hours.

[0012] In one possible implementation, the oxidant is a mixed solution of H2O and HNO3, wherein the volume ratio of H2O to HNO3 in the mixed solution is 1:1; after cooling to room temperature, the solution is washed with deionized water and anhydrous ethanol until it is neutral; the drying temperature is 60~80℃; and the drying time is 7 h.

[0013] In one possible implementation, the reaction temperature of the activated carbon / tubular carbon nanofibers added to the oxidant is 100~120℃, and the reaction time is 4h.

[0014] In one possible implementation, the organic solvent is methanol; the 2-methylimidazole solution is 2-methylimidazole dissolved in methanol, and the concentration of 2-methylimidazole in the 2-methylimidazole solution is 0.016 g / mL; the molar ratio of the activated carbon / tubular carbon nanofibers to the Zn(NO3)2·6H2O is 1:1; the stirring time is 5-6 hours; and the washing is performed using anhydrous ethanol.

[0015] According to a second aspect of the present invention, the present invention provides a multi-scale radon gas adsorption material, which is prepared by the preparation method described above, and the pore size of the multi-scale radon gas adsorption material is 0.35-0.44 nm.

[0016] The technical solution adopted in this invention can achieve the following beneficial effects: This invention provides a multi-scale radon adsorbent material, its preparation method, and its application. Using benzyl dichloroethylene as the monomer, anhydrous FeCl3 as the catalyst, 1,2-dichloroethane (DCE) as the dispersed phase solvent, and organosilicon or alkanes as the continuous phase, activated carbon is uniformly mixed with the continuous phase. Combined with a solvothermal method, a one-pot large-scale preparation of AC / TCN / MOF is achieved, constructing an "activated carbon-tubular carbon nanofiber-metal-organic framework" material with a precise multi-level pore structure. The multi-scale radon adsorbent material prepared by this method has a pore size of 0.35-0.44 nm, solving the problem of weak interaction between activated carbon materials and the target gas. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, forming part of the present invention. The illustrative embodiments of the present invention and their descriptions explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 1 of the present invention; Figure 2 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 2 of the present invention; Figure 3 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 3 of the present invention; Figure 4 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 4 of the present invention; Figure 5 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 5 of the present invention; Figure 6 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 6 of the present invention; Figure 7 This is a micropore size distribution diagram of the prior art activated carbon of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0019] Example 1 Preparation of activated carbon / tubular polymer nanofibers: 10 g of benzyl p-dichloroethane was weighed and dissolved in 500 mL of 1,2-dichloroethane. Under mechanical stirring, this solution was added to a three-necked flask containing 4 L of polydimethylsiloxane mixed with activated carbon. Then, 300 mL of a solution of 20 g of anhydrous FeCl3 in 1,2-dichloroethane was added. The system was reacted at 60–100 °C for 6–10 h. Afterward, the mixture was filtered and washed with 1,2-dichloroethane and anhydrous ethanol until the filtrate was colorless and transparent, yielding a reddish-brown solid. The solid was subjected to Soxhlet extraction with anhydrous ethanol and then vacuum dried to obtain activated carbon / tubular polymer nanofibers.

[0020] Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined at 600-700℃ for 5 h under vacuum conditions and then cooled to room temperature in the furnace to obtain activated carbon / tubular carbon nanofibers.

[0021] Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: A mixed solution of H₂O / HNO₃ (volume ratio 1:1) was used as the oxidant for liquid-phase oxidation treatment of carbon materials. 3 g of activated carbon / tubular carbon nanofibers were weighed and added to a three-necked flask containing 1 L of the H₂O / HNO₃ mixed solution under magnetic stirring. The system was reacted at 100–120 °C for 4 h. After the solution cooled to room temperature, it was washed with deionized water and anhydrous ethanol until the solution was neutral. The product was dried in a vacuum oven at 60–80 °C for 7 h to obtain carboxyl-modified activated carbon / tubular carbon nanofiber solids.

[0022] Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite materials: The obtained 3 g of carboxyl-modified activated carbon / tubular carbon nanofiber solid was dispersed in 500 mL of methanol and sonicated for 30 min to obtain a suspension. 3 g of Zn(NO3)2·6H2O was added to the suspension, and the mixture was magnetically stirred at 1000 r / min for 45 min. Subsequently, 8 g of 2-methylimidazole was added to 500 mL of methanol and rapidly added to the stirred suspension, and the mixture was stirred at room temperature for 6 h. Finally, the precipitate was collected by centrifugation and washed with anhydrous ethanol to obtain the multi-scale adsorption material (i.e., activated carbon / tubular carbon nanofiber / metal-organic framework composite material).

[0023] Pore ​​size distribution tests were performed on multi-scale adsorption materials.

[0024] First, the multi-scale adsorbent material was prepared into uniform particles. Then, it was pretreated in a vacuum at 150°C for 12 hours to remove adsorbed gases and moisture from the surface. Next, the material was placed in an adsorption instrument (Micromeritics ASAP 2460, USA), with the liquid nitrogen temperature set to 77K. Adsorption isotherms were measured by gradually increasing the nitrogen pressure. The Horvath-Kawazoe (HK) method was used to calculate the pore size distribution of the microporous material based on the nitrogen adsorption isotherm. Its core principle is to average the interaction potential energy between the adsorbate and adsorbent using a thermodynamic model, establishing the relationship between filling pressure and effective pore size. Finally, the HK equation was applied to convert the adsorption data into pore size distribution, and the micropore size was inferred from the potential energy parameters to obtain the micropore size distribution. The calculated pore size of the multi-scale adsorbent material was 0.4459 nm.

[0025] Example 2 Preparation of activated carbon / tubular polymer nanofibers: 30 g of m-dichlorobenzyl was weighed and dissolved in 500 mL of 1,2-dichloroethane. Under mechanical stirring, this solution was added to a three-necked flask containing 6 L of polydimethylsiloxane mixed with activated carbon. Then, 300 mL of a solution of 30 g of anhydrous FeCl3 in 1,2-dichloroethane was added. The reaction was continued at 60 °C for 6 h. Afterward, the mixture was filtered and washed with 1,2-dichloroethane and anhydrous ethanol until the filtrate was colorless and transparent, yielding a reddish-brown solid. The solid was subjected to Soxhlet extraction with anhydrous ethanol and then vacuum dried to obtain activated carbon / tubular polymer nanofibers.

[0026] Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined at 700℃ for 5 h under vacuum conditions and then cooled to room temperature in the furnace to obtain activated carbon / tubular carbon nanofibers.

[0027] Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: Weigh 3 g of activated carbon / tubular carbon nanofibers and add them to a three-necked flask containing 1 L of a 1:1 volume ratio of H₂O and HNO₃ under magnetic stirring. React the mixture at 100 °C for 4 h. After cooling to room temperature, wash the solution with deionized water and anhydrous ethanol until neutral. Dry the product in a vacuum oven at 60 °C for 7 h to obtain carboxyl-modified activated carbon / tubular carbon nanofiber solid.

[0028] Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite materials: The obtained 3 g of carboxyl-modified activated carbon / tubular carbon nanofiber solid was dispersed in 500 mL of methanol and sonicated for 30 min to obtain a suspension. 3 g of Zn(NO3)2·6H2O was added to the suspension, and the mixture was magnetically stirred at 1000 r / min for 45 min. Subsequently, 8 g of 2-methylimidazole was added to 500 mL of methanol and rapidly added to the stirred suspension, and the mixture was stirred at room temperature for 6 h. Finally, the precipitate was collected by centrifugation and washed with anhydrous ethanol to obtain the multi-scale adsorption material (i.e., activated carbon / tubular carbon nanofiber / metal-organic framework composite material).

[0029] Pore ​​size distribution tests were performed on multi-scale adsorption materials.

[0030] First, the multi-scale adsorbent material was prepared into uniform particles. Then, it was pretreated in a vacuum at 150°C for 12 hours to remove adsorbed gases and moisture from the surface. Next, the material was placed in an adsorption apparatus with liquid nitrogen at 77K. Adsorption isotherms were measured by gradually increasing the nitrogen pressure. The Horvath-Kawazoe (HK) method calculates the pore size distribution of the microporous material based on the nitrogen adsorption isotherm. Its core principle is to average the interaction potential energy between the adsorbate and adsorbent using a thermodynamic model, establishing the relationship between filling pressure and effective pore size. Finally, the HK equation was applied to convert the adsorption amount data into pore size distribution, and the micropore size was inferred from the potential energy parameters to obtain the micropore size distribution. The calculated pore size of the multi-scale adsorbent material was 0.3501 nm.

[0031] Example 3 Preparation of activated carbon / tubular polymer nanofibers: 30 g of o-dichlorobenzyl was weighed and dissolved in 500 mL of 1,2-dichloroethane. Under mechanical stirring, this solution was added to a three-necked flask containing 6 L of polydimethylsiloxane mixed with activated carbon. Then, 300 mL of a solution of 30 g of anhydrous FeCl3 in 1,2-dichloroethane was added. The reaction was continued at 60 °C for 6 h. Afterward, the mixture was filtered and washed with 1,2-dichloroethane and anhydrous ethanol until the filtrate was colorless and transparent, yielding a reddish-brown solid. The solid was subjected to Soxhlet extraction with anhydrous ethanol and then vacuum dried to obtain activated carbon / tubular polymer nanofibers.

[0032] Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined at 700℃ for 5 h under vacuum conditions and then cooled to room temperature in the furnace to obtain activated carbon / tubular carbon nanofibers.

[0033] Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: Weigh 3 g of activated carbon / tubular carbon nanofibers and add them to a three-necked flask containing 1 L of a 1:1 volume ratio of H₂O and HNO₃ under magnetic stirring. React the mixture at 100 °C for 4 h. After cooling to room temperature, wash the solution with deionized water and anhydrous ethanol until neutral. Dry the product in a vacuum oven at 60 °C for 7 h to obtain carboxyl-modified activated carbon / tubular carbon nanofiber solid.

[0034] Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite materials: The obtained 3 g of carboxyl-modified activated carbon / tubular carbon nanofiber solid was dispersed in 500 mL of methanol and sonicated for 30 min to obtain a suspension. 3 g of Zn(NO3)2·6H2O was added to the suspension, and the mixture was magnetically stirred at 1000 r / min for 45 min. Subsequently, 8 g of 2-methylimidazole was added to 500 mL of methanol and rapidly added to the stirred suspension, and the mixture was stirred at room temperature for 6 h. Finally, the precipitate was collected by centrifugation and washed with anhydrous ethanol to obtain the multi-scale adsorption material (i.e., activated carbon / tubular carbon nanofiber / metal-organic framework composite material).

[0035] Pore ​​size distribution tests were performed on multi-scale adsorption materials.

[0036] First, the multi-scale adsorbent material was prepared into uniform particles. Then, it was pretreated in a vacuum at 150°C for 12 hours to remove adsorbed gases and moisture from the surface. Next, the material was placed in an adsorption apparatus with liquid nitrogen at 77K. Adsorption isotherms were measured by gradually increasing the nitrogen pressure. The Horvath-Kawazoe (HK) method calculates the pore size distribution of the microporous material based on the nitrogen adsorption isotherm. Its core principle is to average the interaction potential energy between the adsorbate and adsorbent using a thermodynamic model, establishing the relationship between filling pressure and effective pore size. Finally, the HK equation was applied to convert the adsorption amount data into pore size distribution, and the micropore size was inferred from the potential energy parameters to obtain the micropore size distribution. The calculated pore size of the multi-scale adsorbent material was 0.3532 nm.

[0037] Example 4 Preparation of activated carbon / tubular polymer nanofibers: 30 g of p-dichlorobenzyl was weighed and dissolved in 500 mL of 1,2-dichloroethane. Under mechanical stirring, this solution was added to a three-necked flask containing 6 L of n-hexane mixed with activated carbon. Then, 300 mL of a 1,2-dichloroethane solution containing 30 g of anhydrous FeCl3 was added. The reaction was continued at 60 °C for 6 h. Afterward, the mixture was filtered and washed with 1,2-dichloroethane and anhydrous ethanol until the filtrate was colorless and transparent, yielding a reddish-brown solid. The solid was subjected to Soxhlet extraction with anhydrous ethanol and then vacuum dried to obtain activated carbon / tubular polymer nanofibers.

[0038] Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined at 700℃ for 5 h under vacuum conditions and then cooled to room temperature in the furnace to obtain activated carbon / tubular carbon nanofibers.

[0039] Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: Weigh 3 g of activated carbon / tubular carbon nanofibers and add them to a three-necked flask containing 1 L of a 1:1 volume ratio of H₂O and HNO₃ under magnetic stirring. React the mixture at 100 °C for 4 h. After cooling to room temperature, wash the solution with deionized water and anhydrous ethanol until neutral. Dry the product in a vacuum oven at 60 °C for 7 h to obtain carboxyl-modified activated carbon / tubular carbon nanofiber solid.

[0040] Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite materials: The obtained 3 g of carboxyl-modified activated carbon / tubular carbon nanofiber solid was dispersed in 500 mL of methanol and sonicated for 30 min to obtain a suspension. 3 g of Zn(NO3)2·6H2O was added to the suspension, and the mixture was magnetically stirred at 1000 r / min for 45 min. Subsequently, 8 g of 2-methylimidazole was added to 500 mL of methanol and rapidly added to the stirred suspension, and the mixture was stirred at room temperature for 6 h. Finally, the precipitate was collected by centrifugation and washed with anhydrous ethanol to obtain the multi-scale adsorption material (i.e., activated carbon / tubular carbon nanofiber / metal-organic framework composite material).

[0041] Pore ​​size distribution tests were performed on multi-scale adsorption materials.

[0042] First, the multi-scale adsorbent material was prepared into uniform particles. Then, it was pretreated in a vacuum at 150°C for 12 hours to remove adsorbed gases and moisture from the surface. Next, the material was placed in an adsorption apparatus with liquid nitrogen at 77K. Adsorption isotherms were measured by gradually increasing the nitrogen pressure. The Horvath-Kawazoe (HK) method calculates the pore size distribution of the microporous material based on the nitrogen adsorption isotherm. Its core principle is to average the interaction potential energy between the adsorbate and adsorbent using a thermodynamic model, establishing the relationship between filling pressure and effective pore size. Finally, the HK equation was applied to convert the adsorption amount data into pore size distribution, and the micropore size was inferred from the potential energy parameters to obtain the micropore size distribution. The calculated pore size of the multi-scale adsorbent material was 0.3554 nm.

[0043] Example 5 Preparation of activated carbon / tubular polymer nanofibers: 30 g of benzyl p-dichloroethane was weighed and dissolved in 500 mL of 1,2-dichloroethane. Under mechanical stirring, this solution was added to a three-necked flask containing 6 L of cyclohexane mixed with activated carbon. Then, 300 mL of a 1,2-dichloroethane solution containing 30 g of anhydrous FeCl3 was added. The reaction was continued at 60 °C for 6 h. Afterward, the mixture was filtered and washed with 1,2-dichloroethane and anhydrous ethanol until the filtrate was colorless and transparent, yielding a reddish-brown solid. The solid was subjected to Soxhlet extraction with anhydrous ethanol and then vacuum dried to obtain activated carbon / tubular polymer nanofibers.

[0044] Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined at 700℃ for 5 h under vacuum conditions and then cooled to room temperature in the furnace to obtain activated carbon / tubular carbon nanofibers.

[0045] Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: Weigh 3 g of activated carbon / tubular carbon nanofibers and add them to a three-necked flask containing 1 L of a 1:1 volume ratio of H₂O and HNO₃ under magnetic stirring. React the mixture at 100 °C for 4 h. After cooling to room temperature, wash the solution with deionized water and anhydrous ethanol until neutral. Dry the product in a vacuum oven at 60 °C for 7 h to obtain carboxyl-modified activated carbon / tubular carbon nanofiber solid.

[0046] Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite materials: The obtained 3 g of carboxyl-modified activated carbon / tubular carbon nanofiber solid was dispersed in 500 mL of methanol and sonicated for 30 min to obtain a suspension. 3 g of Zn(NO3)2·6H2O was added to the suspension, and the mixture was magnetically stirred at 1000 r / min for 45 min. Subsequently, 8 g of 2-methylimidazole was added to 500 mL of methanol and rapidly added to the stirred suspension, and the mixture was stirred at room temperature for 6 h. Finally, the precipitate was collected by centrifugation and washed with anhydrous ethanol to obtain the multi-scale adsorption material (i.e., activated carbon / tubular carbon nanofiber / metal-organic framework composite material).

[0047] Pore ​​size distribution tests were performed on multi-scale adsorption materials.

[0048] First, the multi-scale adsorbent material was prepared into uniform particles. Then, it was pretreated in a vacuum at 150°C for 12 hours to remove adsorbed gases and moisture from the surface. Next, the material was placed in an adsorption apparatus with liquid nitrogen at 77K. Adsorption isotherms were measured by gradually increasing the nitrogen pressure. The Horvath-Kawazoe (HK) method calculates the pore size distribution of the microporous material based on the nitrogen adsorption isotherm. Its core principle is to average the interaction potential energy between the adsorbate and adsorbent using a thermodynamic model, establishing the relationship between filling pressure and effective pore size. Finally, the HK equation was applied to convert the adsorption amount data into pore size distribution, and the micropore size was inferred from the potential energy parameters to obtain the micropore size distribution. The calculated pore size of the multi-scale adsorbent material was 0.3553 nm.

[0049] Example 6 Preparation of activated carbon / tubular polymer nanofibers: 30 g of benzyl p-dichloroethane was weighed and dissolved in 500 mL of 1,2-dichloroethane. Under mechanical stirring, this solution was added to a three-necked flask containing 6 L of n-heptane mixed with activated carbon. Then, 300 mL of a solution of 1,2-dichloroethane containing 30 g of anhydrous FeCl3 was added. The reaction was continued at 60 °C for 6 h. Afterward, the mixture was filtered and washed with 1,2-dichloroethane and anhydrous ethanol until the filtrate was colorless and transparent, yielding a reddish-brown solid. The solid was subjected to Soxhlet extraction with anhydrous ethanol and then vacuum dried to obtain activated carbon / tubular polymer nanofibers.

[0050] Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined at 700℃ for 5 h under vacuum conditions and then cooled to room temperature in the furnace to obtain activated carbon / tubular carbon nanofibers.

[0051] Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: Weigh 3 g of activated carbon / tubular carbon nanofibers and add them to a three-necked flask containing 1 L of a 1:1 volume ratio of H₂O and HNO₃ under magnetic stirring. React the mixture at 100 °C for 4 h. After cooling to room temperature, wash the solution with deionized water and anhydrous ethanol until neutral. Dry the product in a vacuum oven at 60 °C for 7 h to obtain carboxyl-modified activated carbon / tubular carbon nanofiber solid.

[0052] Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite materials: 3 g of the obtained carboxyl-modified activated carbon / tubular carbon nanofiber solid was dispersed in 500 mL of methanol and sonicated for 30 min to obtain a suspension. 3 g of Zn(NO3)2·6H2O was added to the suspension, and the mixture was magnetically stirred at 600–1000 r / min for 45 min. Subsequently, 8 g of 2-methylimidazole was added to 500 mL of methanol and rapidly added to the stirred suspension. The mixture was stirred at room temperature for 5–6 h. Finally, the precipitate was collected by centrifugation and washed with anhydrous ethanol to obtain the multi-scale adsorption material (i.e., activated carbon / tubular carbon nanofiber / metal-organic framework composite material).

[0053] Pore ​​size distribution tests were performed on multi-scale adsorption materials.

[0054] First, the multi-scale adsorbent material was prepared into uniform particles. Then, it was pretreated in a vacuum at 150°C for 12 hours to remove adsorbed gases and moisture from the surface. Next, the material was placed in an adsorption apparatus with liquid nitrogen at 77K. Adsorption isotherms were measured by gradually increasing the nitrogen pressure. The Horvath-Kawazoe (HK) method calculates the pore size distribution of the microporous material based on the nitrogen adsorption isotherm. Its core principle is to average the interaction potential energy between the adsorbate and adsorbent using a thermodynamic model, establishing the relationship between filling pressure and effective pore size. Finally, the HK equation was applied to convert the adsorption amount data into pore size distribution, and the micropore size was inferred from the potential energy parameters to obtain the micropore size distribution. The calculated pore size of the multi-scale adsorbent material was 0.3621 nm.

[0055] Table 1. Aperture results for different embodiments

[0056] The monomers used in Examples 1 and 4-5 were p-dichlorobenzyl. The continuous phase in Example 1 was polydimethylsiloxane, the continuous phase in Example 4 was n-hexane, the continuous phase in Example 5 was cyclohexane, and the continuous phase in Example 6 was n-heptane. As shown in Table 1, Example 1 had the best adsorption effect (pore size 0.4459 nm) because the radon kinetic diameter is 0.417 nm, which is larger than and close to the kinetic diameter, resulting in the strongest interaction force.

[0057] The monomers in Examples 2 and 3 were m-dichlorobenzyl and o-dichlorobenzyl. Compared with Example 1, Example 1 had the best adsorption effect, with a pore size of 0.4459 nm, which is close to the kinetic diameter of radon gas.

[0058] Figure 1 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 1 of the present invention; Figure 2 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 2 of the present invention; Figure 3 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 3 of the present invention; Figure 4 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 4 of the present invention; Figure 5 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 5 of the present invention; Figure 6 A pore size distribution diagram of the multi-scale radon adsorption material provided in Embodiment 6 of the present invention; Figure 7 This is a micropore size distribution diagram of the activated carbon in the prior art of this invention. As shown in Figure 7, the activated carbon pore size distribution has broad peaks, indicating uneven distribution. Figure 1-6As can be seen, the pore size is the value corresponding to the peak value of the narrow peak. The pore size distribution of the composite material is a narrow peak, and the pore size distribution is concentrated in a small size range, indicating that the pore size uniformity in the material is high.

[0059] This invention uses benzyl dichlorophosphate as the monomer, anhydrous FeCl3 as the catalyst, 1,2-dichloroethane as the dispersed phase solvent, and organosilicon or alkanes as the continuous phase. Activated carbon is uniformly mixed with the continuous phase, and a solvothermal method is used to achieve large-scale one-pot preparation of AC / TCN / MOF. This invention employs a multi-scale control strategy of "macro-micro-nano-molecular". At the "macro-scale," based on activated carbon as the framework, the radioactive inert gas radon adsorption system is further designed with "macro-micro-nano-molecular" multi-scale control to construct a highly efficient multi-level adsorption structure. At the "micro-nano scale," tubular carbon nanofibers (TCN) are selected. This material has a bipolar porous structure, providing ultra-high specific surface area nanopores on the tube walls and large interconnected channels on the core that facilitate mass transfer. At the "molecular scale," metal-organic framework (MOF) materials are selected. These materials have abundant porosity and tunable surface properties, showing great application potential in gas adsorption and separation. By constructing a multi-level porous composite material of "activated carbon-tubular carbon nanofiber-metal-organic framework" with a diameter matching the radon kinetics, the "pore confinement" effect is utilized to solve the problem of weak interaction between activated carbon and target gas.

[0060] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing a multi-scale radon adsorption material, characterized in that, The preparation steps include the following: The preparation of activated carbon / tubular polymer nanofibers involves dissolving monomers in a dispersant to form a dispersion solution, mixing activated carbon with a continuous phase to form a mixed solution, adding the dispersion solution to the mixed solution, then adding a catalyst solution, and reacting at 60~100℃ for 6~10 h. After filtration and washing, a solid is obtained. The solid is then subjected to Soxhlet extraction and vacuum drying to obtain activated carbon / tubular polymer nanofibers. Preparation of activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular polymer nanofibers were calcined under vacuum and cooled to room temperature to obtain activated carbon / tubular carbon nanofibers. Preparation of carboxyl-modified activated carbon / tubular carbon nanofibers: The obtained activated carbon / tubular carbon nanofibers are added to an oxidant for reaction, cooled to room temperature, washed and dried to obtain carboxyl-modified activated carbon / tubular carbon nanofibers. Preparation of activated carbon / tubular carbon nanofiber / metal-organic framework composite material: The obtained carboxyl-modified activated carbon / tubular carbon nanofiber was dispersed in an organic solvent, Zn(NO3)2·6H2O was added, and then 2-methylimidazole solution was added and stirred evenly. After centrifugation, the precipitate was collected and washed to obtain multi-scale adsorption material.

2. The preparation method according to claim 1, characterized in that, The monomer includes any one of p-dichlorobenzyl, m-dichlorobenzyl, and o-dichlorobenzyl.

3. The preparation method according to claim 1, characterized in that, The continuous phase includes any one of polydimethylsiloxane, n-hexane, cyclohexane, and n-heptane; the dispersant is 1,2-dichloroethane; and the concentration of the monomer in the dispersion solution is 120 mg / mL.

4. The preparation method according to claim 2, characterized in that, The catalyst solution is prepared by dissolving the catalyst in a 1,2-dichloroethane solution. The catalyst is anhydrous FeCl3, and the concentration of the anhydrous FeCl3 in the catalyst solution is 75 mg / mL. The volume ratio of the catalyst to the monomer is 1.6:

1.

5. The preparation method according to claim 1, characterized in that, The filter was then washed with 1,2-dichloroethane and anhydrous ethanol.

6. The preparation method according to claim 1, characterized in that, The activated carbon / tubular polymer nanofibers were calcined under vacuum at a temperature of 600-700℃ for 5 hours.

7. The preparation method according to claim 1, characterized in that, The oxidant is a mixed solution of H2O and HNO3, wherein the volume ratio of H2O to HNO3 in the mixed solution is 1:1; after cooling to room temperature, the solution is washed with deionized water and anhydrous ethanol until it is neutral; the drying temperature is 60~80℃ and the drying time is 7 h.

8. The preparation method according to claim 1, characterized in that, The reaction temperature for adding activated carbon / tubular carbon nanofibers to the oxidant is 100~120℃, and the reaction time is 4h.

9. The preparation method according to claim 1, characterized in that, The organic solvent is methanol; the 2-methylimidazole solution is 2-methylimidazole dissolved in methanol, and the concentration of 2-methylimidazole in the 2-methylimidazole solution is 0.016 g / mL; The molar ratio of activated carbon / tubular carbon nanofibers to Zn(NO3)2·6H2O is 1:1; the stirring time is 5-6 hours; and the washing is performed using anhydrous ethanol.

10. A multi-scale radon gas adsorption material, characterized in that, The multi-scale radon adsorption material is prepared by the preparation method according to any one of claims 1-9, and the pore size of the multi-scale radon adsorption material is 0.35-0.44 nm.

Images