Method for removing nickel-63 from radioactive waste liquid

Abstract

Embodiments of the present application provide a method for removing nickel-63 from radioactive waste liquid. The method comprises: mixing an adsorbent and the radioactive waste liquid to form a suspension; oscillating the suspension to adsorb the radioactive waste liquid by the adsorbent; after the adsorbent adsorbs in the radioactive waste liquid for a predetermined time, filtering the suspension and collecting the adsorbent enriched with nickel-63 to obtain radioactive waste liquid with reduced nickel-63 content; wherein the adsorbent comprises at least one of: a metal-organic framework material, a metal-organic framework material and a gamma-Al2O3 composite material, and a metal-organic framework material and a molecular sieve composite material. The method for removing nickel-63 from radioactive waste liquid provided by the embodiments of the present application removes nickel-63 in the radioactive waste liquid by using the metal-organic framework material and its composite material, which is simple to operate, low in cost, and does not produce secondary pollution.

Description

Technical Field

[0001] The embodiments of this application relate to the field of radioactive waste treatment technology, specifically to a method for removing nickel-63 from radioactive waste. Background Technology

[0002] Nickel-63 has wide applications in vacuum electronic devices (pre-ionization sources), gas chromatographs (electron capture detectors, ECDs), toxic agent alarms, and radiation-voltage isotope batteries. However, the preparation of nickel-63 inevitably generates radioactive waste containing nickel-63. Nickel-63 is a moderately toxic nuclide with a half-life of up to 100 years, posing a long-term radiation risk to humans and the environment. Therefore, it is necessary to remove or reduce the activity of nickel-63 in the radioactive waste to facilitate the treatment of radioactive waste.

[0003] Among related technologies, commonly used methods for treating radioactive waste liquids include precipitation, ion exchange, evaporation and concentration, solvent extraction, membrane treatment, electrodialysis, and magnetic separation. However, only a portion of these methods are used to remove nickel-63, and these methods are cumbersome, expensive, and can cause secondary pollution. Summary of the Invention

[0004] In view of the above problems, embodiments of this application provide a method for removing nickel-63 from radioactive waste liquid, comprising: mixing an adsorbent and radioactive waste liquid to form a suspension; shaking the suspension to adsorb the radioactive waste liquid using the adsorbent; after the adsorbent has adsorbed in the radioactive waste liquid for a predetermined time, filtering the suspension and collecting the adsorbent enriched with nickel-63 to obtain radioactive waste liquid with reduced nickel-63 content; wherein the adsorbent comprises at least one of the following: metal-organic framework materials, metal-organic framework materials and γ-Al2O3 composite materials, and metal-organic framework materials and molecular sieve composite materials.

[0005] The method for removing nickel-63 from radioactive waste provided in the embodiments of this application removes nickel-63 from radioactive waste through adsorption. This method is simple to operate, low in cost, and does not generate secondary pollution. The adsorbents used in the embodiments of this application are metal-organic framework materials, metal-organic framework and γ-Al₂O₃ composite materials, and metal-organic framework and molecular sieve composite materials. The inventors have found through research that these materials have good adsorption effects on nickel-63. Therefore, adsorption can achieve a good removal effect of nickel-63 from radioactive waste. Attached Figure Description

[0006] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings.

[0007] Figure 1 This is a schematic flowchart of the method for removing nickel-63 from radioactive waste liquid provided in the embodiments of this application.

[0008] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner that does not affect the understanding of those skilled in the art. Detailed Implementation

[0009] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. It should also be noted that, without conflict, the embodiments and features in the embodiments of this application can be combined with each other to obtain new embodiments.

[0010] This application provides a method for removing nickel-63 from radioactive waste liquid. The radioactive waste liquid can be generated during the preparation of nickel-63, or it can be other waste liquid containing nickel-63; this application does not limit the method. In this embodiment, nickel-63 is removed from the radioactive waste liquid by adsorption.

[0011] Figure 1 This is a schematic flowchart of the method for removing nickel-63 from radioactive waste liquid provided in the embodiments of this application. Figure 1 As shown, the method for removing nickel-63 from radioactive waste liquid may include steps S101 to S103. Specifically, in step S101, the adsorbent and radioactive waste liquid are mixed to form a suspension; in step S102, the suspension is shaken to allow the adsorbent to adsorb the radioactive waste liquid; in step S103, after the adsorbent has adsorbed in the radioactive waste liquid for a predetermined time, the suspension is filtered and the adsorbent enriched with nickel-63 is collected, resulting in radioactive waste liquid with reduced nickel-63 content.

[0012] In step S101, the adsorbent and radioactive waste liquid are mixed so that the adsorbent can contact and adsorb nickel-63 in the radioactive waste liquid. In some embodiments, the adsorbent and radioactive waste liquid can be mixed in a closed sample container to prevent the radioactive waste liquid from polluting the environment.

[0013] In step S102, the suspension is shaken to allow the adsorbent to adsorb the radioactive waste liquid. In some embodiments, the sample container can be placed in a shaker, and the adsorbent and radioactive waste liquid in the sample can be shaken to achieve adsorption. Shaking allows the nickel-63 in the radioactive waste liquid to come into full contact with the adsorbent, so that the nickel-63 can be adsorbed by the adsorbent.

[0014] In step S103, after a predetermined adsorption time, most of the nickel-63 in the radioactive waste liquid has been adsorbed by the adsorbent, and nickel-63 is enriched on the adsorbent. The adsorbent enriched with nickel-63 is filtered out and collected by filtering the suspension, so as to separate nickel-63 from the radioactive waste liquid, thereby obtaining radioactive waste liquid with reduced nickel-63 content.

[0015] The adsorbent includes at least one of the following: metal-organic frameworks (MOFs), composites of metal-organic frameworks and γ-Al2O3 (MOFs@γ-Al2O3), and composites of metal-organic frameworks and molecular sieves (MOFs@molecular sieve).

[0016] For example, the molecular sieve can be 4A zeolite, ZSM-5, SAPO-34, SSZ-13, Ti-MCM-41, etc., and this application does not limit it. The particle size of the metal-organic framework material can be 0.05-100 μm.

[0017] Metal-organic frameworks (MOFs) are a class of porous crystalline materials with periodic structures, formed by the self-assembly of metal centers (composed of metal ions or clusters) and bridging ligands. The inventors of this application have discovered that MOFs and their composites exhibit excellent adsorption performance for nickel-63. Specifically, MOFs possess diverse, designable, and tunable structures, are porous, and have unique structural characteristics such as large specific surface areas and unsaturated metal coordination sites, thus demonstrating excellent adsorption performance for nickel-63.

[0018] The method for removing nickel-63 from radioactive waste provided in the embodiments of this application removes nickel-63 from the radioactive waste through adsorption. This method is simple to operate, low in cost, and does not generate secondary pollution. The adsorbents used in the embodiments of this application are metal-organic framework materials and their composites (i.e., MOFs, MOFs@γ-Al2O3, MOFs@molecular sieves). These materials have good adsorption effects on nickel-63; therefore, adsorption can achieve a good removal effect of nickel-63 from radioactive waste.

[0019] In some embodiments, the pore size of the adsorbent is greater than or equal to that of nickel ions (Ni). 2+ The diameter of a nickel ion. By making the pore size of the adsorbent greater than or equal to the diameter of nickel ions, it is easier for nickel ions to enter the pores of the adsorbent and be adsorbed by the adsorbent.

[0020] In some embodiments, the metal-organic framework material may include at least one of the following: copper-based metal-organic framework material, zirconium-based metal-organic framework material, aluminum-based metal-organic framework material, iron-based metal-organic framework material, chromium-based metal-organic framework material, and zinc-based metal-organic framework material.

[0021] For example, the metal-organic framework material can be HKUST-1, UiO-66(Zr), UiO-66(Zr)-NH2, UiO-66-MSA, UiO-66(Zr)-(COOH)2, UiO-67(Zr), MOF-801(Zr), PCN-777(Zr), MIL-53(Al), MIL-96(Al), CAU-10(Al), MIL-100(Fe), MIL-101(Fe), MIL-88A(Fe), MIL-88B(Fe), NH2-MIL-88B(Fe), MIL-101(Cr), ZIF-8, or other materials with a pore size greater than or equal to the diameter of a nickel ion. Metal-organic framework materials.

[0022] In some embodiments, step S102 may include: maintaining the suspension in a constant temperature environment at a predetermined temperature and shaking it to adsorb radioactive waste liquid using an adsorbent.

[0023] In this embodiment, a constant temperature environment at a predetermined temperature is beneficial for maximizing the adsorption performance of the adsorbent, enabling it to better adsorb nickel-63. In some embodiments, depending on the specific type of adsorbent, the predetermined temperature may be in the range of 10-50°C.

[0024] In some embodiments, maintaining the suspension in a constant temperature environment at a predetermined temperature and shaking it includes: placing the suspension in a sample container and sealing the sample container; placing the sample container in a constant temperature shaker; adjusting the temperature of the constant temperature shaker to a predetermined temperature; and shaking the sample container.

[0025] The sample container provides space for the adsorbent to adsorb nickel-63 from the radioactive waste liquid. Sealing the sample container prevents the radioactive waste liquid from overflowing during agitation and causing radioactive contamination to the external environment. In some embodiments, the sample container can be made of a radiation-shielding material to prevent damage from the radioactive nickel-63 or injury to operators from the beta rays emitted by nickel-63. The volume of the sample container can be 10-1000 mL, and the adsorption time can be 1-24 h. In some embodiments, the sample container can be a specially customized centrifuge tube, reagent bottle, etc.

[0026] A thermostatic shaker can agitate a sample container while maintaining it at a constant, predetermined temperature. By agitating the sample container, the radioactive waste liquid and adsorbent within it are shaken, ensuring thorough mixing and allowing nickel-63 in the radioactive waste liquid to come into full contact with and be adsorbed by the adsorbent. The rotation speed of the thermostatic shaker can range from 50 to 200 rpm.

[0027] In some embodiments, the amount of adsorbent used is determined based on the volume of the radioactive waste liquid. It is understood that, given a fixed nickel-63 concentration, the volume of the radioactive waste liquid determines the amount of nickel-63. Determining the amount of adsorbent used based on the volume of the radioactive waste liquid ensures that the nickel-63 in the radioactive waste liquid is fully adsorbed while avoiding waste of the adsorbent. In this embodiment, the amount of adsorbent used can be 0.1-100 g·L⁻¹. -1 That is, 0.1-100g of adsorbent can be used for adsorption treatment per liter of radioactive waste liquid.

[0028] In some embodiments, filtering the suspension and collecting the nickel-63-enriched adsorbent includes: filtration of the suspension to obtain a nickel-63-enriched adsorbent and a radioactive waste liquid with reduced nickel-63 content. For example, a vacuum pump can be used to filter the suspension.

[0029] In this embodiment, filtration of the suspension after the shaking adsorption process accelerates the separation of radioactive waste and adsorbent. Simultaneously, it prevents other harmful components in the radioactive waste from entering the external environment and causing pollution. Specifically, a vacuum filtration device can be used to filter and collect the nickel-63-enriched adsorbent.

[0030] In some embodiments, metal salts and corresponding organic ligands can be dissolved in a solvent in a certain proportion and reacted to synthesize metal-organic framework materials. The solvent used can be water or an organic solvent. Synthesis methods include, but are not limited to, the following: hydrothermal method and microwave method. When synthesizing metal-organic framework materials, a suitable method can be selected according to actual needs.

[0031] Specifically, taking UiO-66(Zr)-(COOH)2 as an example, the synthesis method may include the following steps: At room temperature, 2.3 g ZrCl4 (0.01 mol) and 4.3 g pyromellitic acid (PMA, 0.017 mol) are added to 50 mL of deionized water. After being dispersed evenly, the mixed solution is placed in a high-temperature and high-pressure reactor, and the temperature is raised from room temperature to 100°C at a rate of 1°C / min and maintained for 24 hours. After naturally cooling to room temperature, the gel is washed three times with deionized water. Subsequently, the washed gel is dispersed in ultrapure water (gel to ultrapure water volume ratio of approximately 1:4-5), placed in a reactor, and the temperature is raised from room temperature to 100°C at a rate of 0.5°C / min and maintained for 24 hours. After naturally cooling to room temperature, the gel is washed three times with deionized water and acetone, respectively. After washing, the product was dried at 70°C for 16 hours to obtain UiO-66(Zr)-(COOH)2, which is a white powder.

[0032] After synthesizing UiO-66(Zr)-(COOH)2, it can be used as an adsorbent to adsorb nickel-63 from radioactive waste. For example, 0.1 g of UiO-66(Zr)-(COOH)2 and 20 mL of radioactive waste containing nickel-63 can be placed in a 50 mL centrifuge tube. The amount of adsorbent used (i.e., the amount of UiO-66(Zr)-(COOH)2 per 1 L of solution, in g·L⁻¹) is specified. -1 ) is 5g·L -1 The centrifuge tubes containing the adsorbent and the radioactive waste containing nickel-63 were then placed in a constant-temperature shaker, set at 25°C and 200 rpm, and shaken for 4 hours for adsorption. After shaking, the container was removed, and the suspension formed by the mixture of adsorbent and radioactive waste was poured into a prepared vacuum filtration device for filtration, thereby obtaining an adsorbent enriched with nickel-63 and radioactive waste with reduced nickel-63 content.

[0033] In some embodiments, metal-organic framework materials can be loaded onto the surface of γ-Al₂O₃ to synthesize metal-organic framework-γ-Al₂O₃ composite materials. Loading methods include, but are not limited to, lamination and in-situ growth methods. During synthesis, a suitable loading method can be selected according to actual needs.

[0034] Specifically, taking the HKUST-1@γ-Al2O3 composite material as an example of a metal-organic framework material and γ-Al2O3 composite material, the synthesis method can include the following steps: HKUST-1 is loaded onto the surface of γ-Al2O3 that has been pre-activated at 200℃ using a layer-by-layer (LBL, also known as liquid phase epitaxy) method to obtain the HKUST-1@γ-Al2O3 composite material. The impregnation sequence of γ-Al2O3 is as follows: 1) Impregnation in an ethanol solution of 50 mM trimesic acid for 40 minutes; 2) Impregnation in ethanol for 5 minutes; 3) Impregnation in an ethanol solution of 50 mM Cu(CH3COO)2·3H2O for 20 minutes; 4) Impregnation in ethanol for 5 minutes. Steps 1)-4) constitute one cycle, and this impregnation cycle is repeated four times. The product is then dried at 50℃ for 30 minutes to obtain the HKUST-1@γ-Al2O3 composite material.

[0035] After synthesizing the HKUST-1@γ-Al2O3 composite material, it can be used as an adsorbent to adsorb nickel-63 from radioactive waste. For example, 1 g of HKUST-1@γ-Al2O3 composite material and 200 mL of radioactive waste containing nickel-63 can be placed in a 500 mL reagent bottle. The amount of adsorbent used (i.e., the amount of HKUST-1@γ-Al2O3 composite material per 1 L of solution, in g·L⁻¹) is specified. -1 ) is 5g·L -1 The reagent bottle containing the adsorbent and the radioactive waste liquid containing nickel-63 was placed in a constant-temperature shaker, set at 20°C and 100 rpm, and shaken for 24 hours for adsorption. After shaking, the reagent bottle was removed, and the suspension was poured into a prepared vacuum filtration device for filtration, thereby obtaining the adsorbent enriched with nickel-63 and the radioactive waste liquid with reduced nickel-63 content.

[0036] In some embodiments, a molecular sieve or a composite material of a molecular sieve and a metal, along with a corresponding organic ligand, are mixed in a solvent and reacted to synthesize a metal-organic framework material and a molecular sieve composite material. The solvent used can be water or an organic solvent. Synthesis methods include, but are not limited to, hydrothermal methods and microwave methods.

[0037] In some embodiments, when the molecular sieve contains the metal required for synthesizing metal-organic framework materials, the molecular sieve can be mixed with the corresponding organic ligand in a solvent and reacted to obtain MOFs@molecular sieve. When the molecular sieve does not contain the required metal, the composite material of the molecular sieve and the metal and the corresponding organic ligand can be mixed with a solvent and reacted to obtain MOFs@molecular sieve.

[0038] Specifically, taking the MIL-53@4A zeolite molecular sieve composite material as an example of a metal-organic framework material and molecular sieve composite, the synthesis method may include the following steps: At room temperature, 0.955 g of 4A zeolite and 0.599 g of terephthalic acid (organic ligand, molar ratio 1:1) are added to 45 ml of deionized water and stirred for 2 h. The mixed solution is then placed in a reaction vessel and reacted at 150 °C for 8 h. After the reaction vessel cools, the precursor is obtained by filtration. The precursor is dissolved in 45 ml of N,N-dimethylformamide (DMF) and reacted at 150 °C for 20 h. After cooling, the mixture is filtered to obtain the MIL-53@4A zeolite molecular sieve composite material.

[0039] After synthesizing the MIL-53@4A zeolite molecular sieve composite material, it can be used as an adsorbent to adsorb nickel-63 from radioactive waste. For example, 1 g of the MIL-53@4A zeolite molecular sieve composite material and 200 mL of radioactive waste containing nickel-63 can be placed in a 500 mL reagent bottle. The amount of adsorbent used (i.e., the amount of MIL-53@4A zeolite molecular sieve composite material per 1 L of solution, in g·L⁻¹) is specified. -1 ) is 5g·L -1 The reagent bottle containing the adsorbent and the radioactive waste liquid containing nickel-63 was placed in a constant-temperature shaker, set at 25°C and 140 rpm, and shaken for 8 hours for adsorption. After shaking, the container was removed, and the suspension was poured into a prepared vacuum filtration device for filtration, thereby obtaining the adsorbent enriched with nickel-63 and the radioactive waste liquid with reduced nickel-63 content.

[0040] In summary, the method for removing nickel-63 from radioactive waste provided in this application is a low-energy, simple, and green method for removing nickel-63 from radioactive waste. It does not require complex steps or strong acid and alkali reagents for pollution. Nickel-63 can be removed simply by adsorption, resulting in an adsorbent enriched with nickel-63 and radioactive waste with reduced nickel-63 content.

[0041] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for removing nickel-63 from radioactive waste liquid, characterized in that, include: The adsorbent and radioactive waste liquid are mixed to form a suspension; The suspension is agitated to allow the adsorbent to adsorb the radioactive waste liquid. After the adsorbent adsorbs in the radioactive waste liquid for a predetermined time, the suspension is filtered and the adsorbent enriched with nickel-63 is collected to obtain radioactive waste liquid with reduced nickel-63 content. The adsorbent is a composite material of metal-organic framework and molecular sieve. The method further includes: mixing a molecular sieve or a composite material of a molecular sieve and a metal and a corresponding organic ligand in a solvent, and reacting to synthesize the metal-organic framework material and the molecular sieve composite material.

2. The method according to claim 1, characterized in that, The oscillation of the suspension includes: The suspension is kept in a constant temperature environment at a predetermined temperature and shaken to utilize the adsorbent to adsorb the radioactive waste liquid.

3. The method according to claim 2, characterized in that, The step of maintaining the suspension in a constant temperature environment at a predetermined temperature and then agitating it includes: Place the suspension in a sample container and seal the sample container; Place the sample container inside a constant temperature shaker; Adjust the temperature of the thermostatic oscillator to the predetermined temperature; The sample container is shaken.

4. The method according to claim 3, characterized in that, The amount of adsorbent to be used is determined based on the volume of the radioactive waste liquid.

5. The method according to claim 1, characterized in that, The process of filtering the suspension and collecting the adsorbent enriched with nickel-63 includes: The suspension was filtered to obtain an adsorbent enriched with nickel-63 and a radioactive waste liquid with reduced nickel-63 content.

6. The method according to claim 1, characterized in that, The pore size of the adsorbent is greater than or equal to the diameter of a nickel ion.

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