A method for preparing an adsorbent and the adsorbent itself.

Abstract

This application provides a method for preparing an adsorbent and an adsorbent. The preparation method includes the following steps: immersing adsorbent particles in an acidic solution for a first predetermined time; washing the adsorbent particles and immersing them in an alkaline solution for a second predetermined time; washing and drying the adsorbent particles; and immersing the adsorbent particles in a bismuth salt solution for a third predetermined time. The adsorbent prepared by the method of this application has good adsorption performance.

Description

Technical Field

[0001] This application relates to the field of radionuclide adsorption technology, and in particular to a method for preparing an adsorbent and the adsorbent itself. Background Technology

[0002] The integrated fast reactor dry reprocessing method uses a metal chloride eutectic molten salt (LiCl-KCl) as the electrolytic medium to dissolve radionuclides in spent fuel as metal chlorides. Then, an electrolytic refining process is used to electrolytically separate U and Pu from the spent fuel, as well as to separate and extract transuranic and actinide nuclides. The reactor temperature in this process is typically above 600 degrees Celsius. At this temperature, LiCl and KCl exist as liquid metal molten salts, while various actinide, lanthanide, and alkali metal chlorides (such as LaCl3, NdCl3, CsCl, and SrCl2) and other fragmented element chlorides volatilize from the system. These chlorides are transferred through metal pipes and deposit inside the equipment, causing significant radioactive contamination and placing immense pressure on subsequent decontamination of nuclear power components.

[0003] In related technologies, radioactive gas adsorbent materials are mostly used for the adsorption and functionalization of radionuclides at low temperatures, ultra-low temperatures, and liquid phases, such as activated carbon, ion exchange resins, MOF (Metal-Organic Frameworks), and COF (Covalent Organic Frameworks). However, their selective adsorption of metal chlorides is not strong, making them unsuitable for the high-temperature and high-irradiation environment of integrated fast reactors, resulting in poor adsorption performance. Summary of the Invention

[0004] In view of this, the main objective of the embodiments of this application is to provide a method for preparing an adsorbent and an adsorbent for improving adsorption effect.

[0005] To achieve the above objectives, the technical solution of this application embodiment is implemented as follows: The first aspect of this application provides a method for preparing an adsorbent, the method comprising the following steps: The adsorbent particles are immersed in an acidic solution for a first set time. The adsorbent particles are washed and then soaked in an alkaline solution for a second set time. The adsorbent particles are cleaned and then dried. The adsorbent particles are immersed in a bismuth salt solution for a third set time.

[0006] In one embodiment, the acidic solution is a nitric acid solution; and / or, The alkaline solution is a sodium hydroxide solution; and / or, The bismuth salt solution is a bismuth nitrate solution.

[0007] In one embodiment, before immersing the adsorbent particles in an acidic solution for a first predetermined time, the preparation method further includes: The raw materials, deionized water, and foaming agent are mixed and stirred to form a mixture; wherein the raw materials include zeolite molecular sieves; The mixture is dried to form a ceramic green body; The ceramic green body is sintered to form a porous ceramic, and the porous ceramic is crushed and sieved to obtain the adsorbent particles.

[0008] In one embodiment, the raw materials further include sodium salt of isobutylene-maleic anhydride copolymer and sodium carboxymethyl cellulose. Before mixing the raw materials, deionized water, and foaming agent to form a mixture, the preparation method further includes: The zeolite molecular sieve is crushed and sieved. The sodium salt of isobutylene-maleic anhydride copolymer and the sodium carboxymethyl cellulose are added to the sieved zeolite molecular sieve and mixed by shaking to obtain the raw material.

[0009] In one embodiment, the foaming agent is triethanolamine dodecyl sulfate.

[0010] In one embodiment, after mixing and stirring the raw materials, deionized water, and foaming agent to form a mixture, the preparation method further includes: The mixture is allowed to stand at room temperature to foam for a fourth set time.

[0011] In one embodiment, the acidic solution is a nitric acid solution, the concentration of which is greater than or equal to 0.5 mol / L and less than or equal to 2 mol / L; and / or, The alkaline solution is a sodium hydroxide solution, wherein the concentration of the sodium hydroxide solution is greater than or equal to 1 mol / L and less than or equal to 4 mol / L; and / or, The bismuth salt solution is a bismuth nitrate solution, and the concentration of the bismuth nitrate solution is greater than 0 mol / L and less than or equal to 1 mol / L.

[0012] In one embodiment, the adsorbent particles are soaked in a bismuth salt solution for a third predetermined time to obtain a mixed solution; the preparation method further includes: The mixed solution was dehydrated and dried in an inert atmosphere furnace at a set temperature to obtain the adsorbent with bismuth active groups loaded on its surface.

[0013] In one embodiment, the set temperature is greater than or equal to 250°C and less than or equal to 350°C.

[0014] A second aspect of this application provides an adsorbent prepared by any of the above-described methods, wherein the surface of the adsorbent is loaded with bismuth active groups.

[0015] This application provides a method for preparing an adsorbent and the adsorbent itself. On one hand, adsorbent particles are immersed in an acidic solution for a first predetermined time, and after washing, they are immersed in an alkaline solution for a second predetermined time. This acid-base activation of the adsorbent imparts more pores to its surface, significantly increasing the adsorption flux for metal chlorides and improving its adsorption effect. On the other hand, the adsorbent particles are dried and then immersed in a bismuth salt solution for a third predetermined time. This allows the surface of the adsorbent to be loaded with bismuth active groups, utilizing the high-temperature stable phase BiOCl formed by the combination of bismuth and chlorides to achieve strong locking of metal chlorides. Thus, the adsorbent possesses not only the original physical adsorption effect but also a greater number of chemical adsorption active sites. Meanwhile, since the high-temperature stability of Bi-O groups is usually higher than 1200℃, it is more stable than organic surface functional groups in related technologies, such as ion exchangers and quaternary ammonium salts. This makes the adsorbent more suitable for the high-temperature and high-irradiation environment in the integrated fast reactor, resulting in better adsorption performance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the steps of a method for preparing an adsorbent according to an embodiment of this application; Figure 2 This is a flowchart illustrating a method for preparing an adsorbent according to another embodiment of this application.

[0017] Explanation of reference numerals in the attached figures 10. Crucible; 20. Oven; 30. High-temperature muffle furnace; 40. Adsorbent; 50. Inert atmosphere furnace; 60. Raw material; 70. Adsorbent granules. Detailed Implementation

[0018] In the description of the embodiments of this application, technical terms such as "first," "second," and "third" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] One embodiment of this application provides a method for preparing adsorbent 40. Please refer to [link to relevant documentation]. Figure 1 and Figure 2 The preparation method includes the following steps: Step S1: Immerse the adsorbent particles 70 in an acidic solution for a first set time.

[0021] Step S2: Clean the adsorbent particles 70 and soak them in an alkaline solution for a second set time.

[0022] Step S3: Clean the adsorbent particles 70 and dry them.

[0023] Step S4: Immerse the adsorbent particles 70 in a bismuth salt solution for a third set time.

[0024] Specifically, the adsorbent particles 70 are porous particles with adsorption effect, and the specific type of raw material 60 used to form the adsorbent particles 70 can be set according to the actual situation.

[0025] For example, the raw material 60 forming the adsorbent particles 70 includes at least a zeolite molecular sieve. For instance, 5A zeolite molecular sieve has a complex crystal structure mainly composed of elements such as Si, Al, and O, with its crystal structure primarily being M... x / n [(AlO2) x [·(SiO2)y·mH2O]. The oxides of Si and Al impart high thermal stability, typically above 1000℃, which can effectively ensure the structural stability of the integrated fast reactor at high temperatures above 600℃. In particular, the optimized design of complex mesopores can maintain stable physical adsorption sites under high and ultra-high temperature conditions.

[0026] In step S1, the adsorbent particles 70 are immersed in an acidic solution for a first set time, i.e., the adsorbent particles 70 are subjected to acid washing and activation treatment. This process imparts more pores to the surface of the adsorbent particles 70, especially activating and expanding the pores for the molecular size of high-temperature gaseous metal chlorides. The specific type of acidic solution can be determined according to actual conditions. Preferably, the acidic solution is a nitric acid solution, which can achieve a better acid activation effect. Of course, in other embodiments, a sulfuric acid solution can also be used as the acidic solution.

[0027] The adsorbent particles 70 need to be immersed in an acidic solution for a first set time, which can be set according to actual conditions. For example, the first set time is greater than or equal to 50 minutes, such as 50 minutes or 1 hour. This ensures a better pore-expanding effect on the surface of the adsorbent particles 70.

[0028] In step S2, the adsorbent particles 70 can be washed with a large amount of deionized water. Afterward, the washed adsorbent particles 70 are subjected to alkaline activation treatment, which further enriches the surface of the adsorbent particles 70 with more pores, especially activating and expanding the pores for the molecular size of high-temperature gaseous metal chlorides. The specific type of alkaline solution can be determined according to actual conditions. Preferably, the alkaline solution is a sodium hydroxide solution, which can achieve a better alkaline activation effect.

[0029] The adsorbent particles 70 need to be soaked in an alkaline solution for a second set time, which can be set according to actual conditions. For example, the second set time is greater than or equal to 5 hours, such as 5 hours or 6 hours. This ensures a better pore-expanding effect on the surface of the adsorbent particles 70.

[0030] In step S3, the adsorbent particles 70 may be washed with a large amount of deionized water. Afterwards, the adsorbent particles 70 are dried to keep them dry.

[0031] In step S4, the adsorbent particles 70 are immersed in a bismuth salt solution. The Bi reacts with the matrix at high temperature to spontaneously combine and form stable Bi-O groups, providing additional chemical adsorption active sites for the adsorption of high-temperature metal chlorides. Thus, the surface functionalization modification of the adsorbent particles 70 can be achieved.

[0032] The specific type of bismuth salt solution can be determined according to the actual situation. Preferably, the bismuth salt solution is a bismuth nitrate solution. Using a bismuth nitrate solution can better achieve the loading of Bi active groups.

[0033] It should be noted that bismuth salt solutions correspond to acidic solutions. For example, an acidic solution is a nitric acid solution, and a bismuth salt solution is a bismuth nitrate solution.

[0034] Another embodiment of this application provides an adsorbent 40, which is prepared by the preparation method of adsorbent 40 described in any embodiment of this application, and the surface of the adsorbent 40 is loaded with bismuth active groups.

[0035] In related technologies, ceramic-based porous materials, primarily mullite, alumina, and kaolin, are used for adsorption and filtration of high-temperature radioactive gases, typically for treating high-temperature gaseous I2 and Cl2 radioactive gases. However, the physicochemical properties of gaseous metal chlorides in integrated fast reactors differ from those of gaseous I2, and the temperature of the adsorbent also differs. Typically, the temperature in integrated fast reactors is much higher than the temperature at the tail end of nuclear power plants where gaseous I2 exists. According to gas diffusion theory, the adsorption flux for radioactive gases theoretically decreases with increasing temperature. Therefore, without functional modification, it will be difficult to achieve adsorption and filtration of high-temperature gaseous metal chlorides.

[0036] In the preparation method of the adsorbent 40 in this embodiment, on the one hand, the adsorbent particles 70 are immersed in an acidic solution for a first set time, and after being washed, the adsorbent particles 70 are immersed in an alkaline solution for a second set time. This acid-base activation of the adsorbent 40 imparts more pores to its surface, significantly increasing the adsorption flux of the adsorbent 40 for metal chlorides and improving its adsorption effect. On the other hand, the adsorbent particles 70 are dried and then immersed in a bismuth salt solution for a third set time. This allows the surface of the adsorbent 40 to be loaded with bismuth active groups, utilizing the high-temperature stable phase BiOCl formed by the combination of bismuth and chlorides to achieve strong locking of metal chlorides. Therefore, the adsorbent 40 possesses not only the original physical adsorption effect but also a richer number of chemical adsorption active sites. Meanwhile, since the high-temperature stability of Bi-O groups is usually higher than 1200℃, it is more stable than organic surface functional groups in related technologies, such as ion exchangers and quaternary ammonium salts. This makes adsorbent 40 suitable for the high-temperature and strong-irradiation environment in the integrated fast reactor, resulting in good adsorption effect of adsorbent 40.

[0037] In related technologies, porous ceramic-based gas adsorbents only involve physical adsorption processes, resulting in rapid desorption at high temperatures. However, the adsorbent 40 prepared using the method described in this application provides a richer array of chemical adsorption active sites on top of the existing physical adsorption. By combining physical and chemical adsorption, it effectively overcomes the problems of high-temperature stability and insufficient gas adsorption flux. Furthermore, acid-base activation treatment and pore expansion, along with surface inorganic functionalization modification, significantly enhance its adsorption flux for metal chlorides. Loading Bi functional groups, which have selective adsorption effects on chlorides, further improves its adsorption performance.

[0038] The specific formation method of the adsorbent particles 70 can be set according to the actual situation.

[0039] For example, please refer to Figure 1 Before immersing the adsorbent particles 70 in an acidic solution for a first set time, the preparation method further includes the following steps: Raw material 60, deionized water and foaming agent are mixed and stirred to form a mixture; wherein, raw material 60 includes zeolite molecular sieve.

[0040] The mixture is dried to form a ceramic green body.

[0041] Ceramic green bodies are sintered to form porous ceramics, which are then crushed and sieved to obtain adsorbent particles 70. This allows for better recrystallization and porosity control of zeolite molecular sieves, enhancing their specific adsorption effect on high-temperature gaseous metal chlorides. The unique pore crystal structure of zeolite molecular sieves (such as 5A molecular sieve) enables the robust adsorption of large molecular particles, including Cs.

[0042] Specifically, the type of foaming agent can be determined according to the actual situation. For example, the foaming agent could be triethanolamine dodecyl sulfate.

[0043] By mixing and stirring raw material 60, deionized water, and foaming agent, a porous and viscous mixture can be formed. After drying the mixture to form a ceramic green body, and then sintering it to form a porous ceramic, followed by crushing and sieving, adsorbent particles 70 can be obtained. This effectively achieves the goal of high-temperature recrystallization.

[0044] In related technologies, radionuclide adsorbents are mainly composed of traditional adsorption and filtration materials such as activated carbon and ion exchange resins, or novel functionalized adsorbent materials, including COF and MOF. Although the above adsorbents have good adsorption effects on radionuclides in the aqueous phase, including Cs and Sr, they face the problem of significantly reduced adsorption effects when faced with high-temperature gaseous radionuclides. At the same time, in the ultra-high temperature environment of integrated fast reactors, some of these adsorbents will vaporize or melt, exhibiting poor high-temperature stability and failing to adapt to the ultra-high temperatures above 600°C in integrated fast reactors.

[0045] The raw material 60 in this embodiment includes zeolite molecular sieves, which have good high-temperature resistance (melting point exceeding 1000℃). The surface functionalization modification used is mainly inorganic modification, which also has high-temperature stability. It can better ensure that it maintains its structural stability in the high-temperature environment of the integrated fast reactor above 600℃. In particular, the optimized design of complex mesopores can maintain stable physical adsorption sites under high and ultra-high temperature conditions.

[0046] It should be noted that raw material 60 may include other materials besides zeolite molecular sieves.

[0047] For example, raw material 60 also includes sodium isobutylene-maleic anhydride copolymer (ISOBAM-104) and sodium carboxymethyl cellulose. Before mixing raw material 60, deionized water, and foaming agent to form a mixture, the preparation method further includes the following steps: Zeolite molecular sieves are crushed and sieved. Sodium isobutylene-maleic anhydride copolymer and sodium carboxymethyl cellulose are added to the sieved zeolite molecular sieves and the mixture is shaken and mixed to obtain raw material 60. This process effectively improves the dispersion and water retention of the mixture, thereby enhancing the strength and sintering performance of the ceramic green body.

[0048] In one embodiment, after mixing and stirring the raw material 60, deionized water, and foaming agent to form a mixture, the preparation method further includes: The mixture is allowed to stand at room temperature to foam for a set time. This promotes the formation of a porous structure.

[0049] The specific concentrations of acidic solutions, alkaline solutions, and bismuth salt solutions can be set according to the actual situation.

[0050] For example, the acidic solution is a nitric acid solution with a concentration greater than or equal to 0.5 mol / L and less than or equal to 2 mol / L. For example, 0.5, 1, or 2 mol / L. Controlling the concentration of the nitric acid solution within this range allows for better acid washing and activation of the adsorbent particles 70.

[0051] For example, the alkaline solution is a sodium hydroxide solution with a concentration greater than or equal to 1 mol / L and less than or equal to 4 mol / L. For instance, concentrations of 1, 2, 3, or 4 mol / L. Controlling the concentration of the sodium hydroxide solution within this range allows for better alkaline washing and activation of the adsorbent particles 70.

[0052] For example, the bismuth salt solution is a bismuth nitrate solution with a concentration greater than 0 mol / L and less than or equal to 1 mol / L, such as 0.5 or 1 mol / L. Controlling the concentration of the bismuth nitrate solution within this range allows for better loading of Bi active groups onto the adsorbent particles 70.

[0053] In one embodiment, please refer to Figure 1 The adsorbent particles 70 are immersed in a bismuth salt solution for a third set time to obtain a mixed solution. The preparation method also includes the following steps: The mixed solution is dehydrated and dried in an inert atmosphere furnace 50 at a set temperature to obtain an adsorbent 40 with bismuth active groups loaded on its surface.

[0054] Specifically, since Bi reacts and spontaneously combines with the matrix at high temperature to form stable Bi-O groups, the mixed solution can be dehydrated and dried in an inert atmosphere furnace 50 at a set temperature to complete the loading of Bi active groups.

[0055] It should be noted that the specific temperature setting can be adjusted according to the actual situation.

[0056] For example, the set temperature is greater than or equal to 250°C and less than or equal to 350°C. Such as 250°C, 300°C, or 350°C. Preferably, the set temperature is 300°C.

[0057] In one specific embodiment, please refer to Figure 1 The preparation method of adsorbent 40 includes a green preparation stage, a high-temperature recrystallization stage, and a surface functionalization modification stage.

[0058] In the green body preparation stage: 5A molecular sieves are crushed and sieved to 40 mesh using a ball mill. A certain amount of ISOBAM-104 and sodium carboxymethyl cellulose are added to the powder, and the mixture is shaken in a shaker for 5 minutes. The uniformly shaken powder is poured into crucible 10, and deionized water and triethanolamine dodecyl sulfate are added and stirred until a porous and viscous state is reached. After the crucible 10 is allowed to stand and foam at room temperature for a period of time, it is placed in an oven 20 to dry.

[0059] During the high-temperature recrystallization stage, the dried ceramic green is placed in a high-temperature muffle furnace 30 and sintered into porous ceramics according to certain process parameters. After cooling to room temperature, it is removed. Then, the sintered porous ceramic is crushed and passed through a 40-mesh sieve to remove fine particles.

[0060] In the surface functionalization modification stage, porous adsorbent particles 70 were immersed in HNO3 solution and modified at room temperature for 1 hour. Then, the surface of adsorbent 40 was washed with a large amount of deionized water. After washing, the adsorbent particles 70 were immersed in NaOH solution and modified at high temperature for 6 hours. Then, the surface of adsorbent 40 was washed with a large amount of deionized water and placed in oven 20 to dry. After drying, the adsorbent particles 70 were immersed in Bi(NO3)3 solution of a certain concentration and modified at room temperature for 8 hours. Then, they were transferred to inert atmosphere furnace 50 and dehydrated and dried at 300℃ for 2 hours to complete the loading of Bi active groups.

[0061] During the green body preparation stage, the amount of ISOBAM-104 sample added is 0.1~5wt%, meaning the mass of ISOBAM-104 accounts for 0.1~5wt% of the mass of the 5A molecular sieve. The amount of sodium carboxymethyl cellulose sample added is 0.1~3wt%, meaning the mass of sodium carboxymethyl cellulose accounts for 0.1~3wt% of the mass of the 5A molecular sieve. The static foaming time is generally 6~24 hours, and the drying time in an oven at 20°C is not less than 6 hours.

[0062] Compared to commercially available 5A molecular sieves without pore-expanding stimulation, the adsorbent 40 in this embodiment exhibits significantly enhanced selectivity for high-temperature CsCl vapor. Simultaneously, through Bi functionalization loading on its surface, robust chemical binding sites are formed, and the Bi-O functional groups on its surface can rapidly and firmly bind Cl ions, thereby improving the overall adsorption effect through chemisorption. In one embodiment, an adsorption verification test was conducted on the adsorbent 40 prepared by the method for preparing adsorbent 40.

[0063] Specifically, a fixed amount of adsorbent 40 (3g) was loaded into the column, and both ends of the column were sealed with metal mesh. A certain mass of mixed metal chloride CsCl (total mass 1.5g) was placed at the front end of the column, placed in a ceramic crucible 10, and placed in the high-temperature zone of a muffle furnace near the argon cylinder. The argon gas flow rate was set to 100mL / min, and then the heating operation was started, with the equilibrium temperature set at 700℃ and the heating rate at 10℃ / min. During this process, the three-way valve in the middle was closed, so that the carrier gas did not pass through the adsorption column. Samples were taken every half hour below the valve, and deionized water was used as the absorbent. The concentration of CsCl in the gas source phase was tested. After that, the three-way valve was closed, and the valve of the adsorption column was opened. The argon gas carrying the high-temperature metal chloride vapor began to be adsorbed by the adsorbent 40 (the temperature zone of the adsorption column was 700℃). Samples were taken at regular intervals until 8 hours later, then sampling was stopped, and the cooling operation began. The concentrations of Cs and Cl in the absorbent were quantified by ICP-MS, and adsorption breakthrough curves were plotted.

[0064] The functionalized (negative Bi) molecular sieve exhibits excellent adsorption performance for CsCl vapor, with a saturated adsorption capacity of up to 477 mg / g. Under the same conditions, this performance surpasses that of montmorillonite (134 mg / g) from the Korea Atomic Energy Research Institute (KEARI), kaolin (367 mg / g) from the US EPA, and activated alumina (287 mg / g) from Oak Ridge National Laboratory, placing it among the world's leading adsorption performers. Furthermore, the porous ceramic-based adsorbent 40, prepared using the same method as adsorbent 40 and with inorganic surface modification, retains good adsorption capacity even after high-temperature adsorption experiments at 700℃, demonstrating strong thermal stability. This indicates better industrial applicability compared to activated carbon, ZIF, COF, and MOF materials studied in related technologies (which generally decompose above 200℃).

[0065] In the description of this application, the references to terms such as "in one embodiment," "in some embodiments," "in a specific embodiment," or "exemplary," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the embodiments of this application. In this application, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine the different embodiments or examples described in this application, as well as the features of the different embodiments or examples.

[0066] The above are merely preferred embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the protection scope of this application.

Claims

1. A method for preparing an adsorbent, characterized in that, The preparation method includes the following steps: The adsorbent particles are immersed in an acidic solution for a first set time. The adsorbent particles are washed and then soaked in an alkaline solution for a second set time. The adsorbent particles are cleaned and then dried. The adsorbent particles are immersed in a bismuth salt solution for a third set time.

2. The method for preparing the adsorbent according to claim 1, characterized in that, The acidic solution is a nitric acid solution; and / or, The alkaline solution is a sodium hydroxide solution; and / or, The bismuth salt solution is a bismuth nitrate solution.

3. The method for preparing the adsorbent according to claim 1 or 2, characterized in that, Before immersing the adsorbent particles in an acidic solution for a first predetermined time, the preparation method further includes: The raw materials, deionized water, and foaming agent are mixed and stirred to form a mixture; wherein the raw materials include zeolite molecular sieves; The mixture is dried to form a ceramic green body; The ceramic green body is sintered to form a porous ceramic, and the porous ceramic is crushed and sieved to obtain the adsorbent particles.

4. The method for preparing the adsorbent according to claim 3, characterized in that, The raw materials also include sodium salt of isobutylene-maleic anhydride copolymer and sodium carboxymethyl cellulose. Before mixing and stirring the raw materials, deionized water, and foaming agent to form a mixture, the preparation method further includes: The zeolite molecular sieve is crushed and sieved. The sodium salt of isobutylene-maleic anhydride copolymer and the sodium carboxymethyl cellulose are added to the sieved zeolite molecular sieve and mixed by shaking to obtain the raw material.

5. The method for preparing the adsorbent according to claim 3, characterized in that, The foaming agent is triethanolamine dodecyl sulfate.

6. The method for preparing the adsorbent according to claim 3, characterized in that, After mixing and stirring the raw materials, deionized water, and foaming agent to form a mixture, the preparation method further includes: The mixture is allowed to stand at room temperature to foam for a fourth set time.

7. The method for preparing the adsorbent according to claim 1, characterized in that, The acidic solution is a nitric acid solution, wherein the concentration of the nitric acid solution is greater than or equal to 0.5 mol / L and less than or equal to 2 mol / L; and / or, The alkaline solution is a sodium hydroxide solution, wherein the concentration of the sodium hydroxide solution is greater than or equal to 1 mol / L and less than or equal to 4 mol / L; and / or, The bismuth salt solution is a bismuth nitrate solution, and the concentration of the bismuth nitrate solution is greater than 0 mol / L and less than or equal to 1 mol / L.

8. The method for preparing the adsorbent according to claim 1 or 2, characterized in that, The adsorbent particles are soaked in a bismuth salt solution for a third predetermined time to obtain a mixed solution. The preparation method further includes: The mixed solution was dehydrated and dried in an inert atmosphere furnace at a set temperature to obtain the adsorbent with bismuth active groups loaded on its surface.

9. The method for preparing the adsorbent according to claim 8, characterized in that, The set temperature is greater than or equal to 250°C and less than or equal to 350°C.

10. An adsorbent, characterized in that, The adsorbent is prepared by the method of any one of claims 1-9, and the surface of the adsorbent is loaded with bismuth active groups.

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