Radioactive organic solid waste treatment method based on ionic liquid

Abstract

The invention discloses a radioactive organic solid waste treatment method based on ionic liquid, which comprises the following steps: pretreatment and dissolution: crushing radioactive organic solid waste, adding functionalized ionic liquid to form a mixed system, controlling temperature and pressure, and stirring to fully dissolve the organic solid waste; catalytic oxidation mineralization: adding a catalyst and an oxidizing agent into the mixed system, transferring the mixed system into a catalytic oxidation reaction device, and carrying out a reaction under certain temperature and pressure conditions to mineralize organic components into CO2 and H2O; radionuclide separation: adopting a selective extraction or ion exchange method to separate radionuclide from the reacted system, and obtaining a solid phase or an organic phase rich in radionuclide and a purified ionic liquid phase after separation; regeneration and circulation of the ionic liquid: regenerating the purified ionic liquid phase, removing moisture and low-boiling-point impurities in the ionic liquid phase, and realizing regeneration and circulation of the ionic liquid.

Description

Technical Field

[0001] This invention relates to the field of radioactive waste treatment technology, and in particular to a method for treating radioactive organic solid waste based on ionic liquids. Background Technology

[0002] Currently, in the field of radioactive organic solid waste treatment, traditional treatment technologies generally suffer from technical limitations and insufficient environmental safety, making it difficult to meet the core requirements of modern environmental protection for volume reduction, harmlessness, and resource recovery. The drawbacks of various treatment methods are becoming increasingly prominent. Among them, incineration, as an early and widely used volume reduction technology, can achieve a certain degree of volume reduction of solid waste, but its potential secondary pollution risk is extremely harmful. During the high-temperature incineration process, chlorine-containing and benzene-containing components in organic solid waste easily react with flue gas to generate dioxins, highly toxic persistent organic pollutants. These substances are chemically very stable, difficult to degrade naturally, and have strong carcinogenic, teratogenic, and mutagenic properties. Once they diffuse into the atmosphere, soil, or water bodies through flue gas, they will form a cross-regional ecological pollution chain, causing long-term and irreversible impacts on the survival of animals and plants and human health. More importantly, the incineration process cannot effectively fix or eliminate radionuclides. The nuclides may escape in the form of aerosols with the incineration flue gas or remain in the bottom ash and fly ash. This not only increases the difficulty of subsequent flue gas purification and residue treatment, but also expands the spread of radioactive pollution and further increases the cost of environmental management.

[0003] Conventional chemical treatment methods, such as oxidation, reduction, and hydrolysis, also have significant shortcomings. Their core limitation lies in the difficulty of achieving complete mineralization of organic solid waste. These methods often involve chemical reagents reacting with the organic components in the solid waste, attempting to destroy the molecular structure of organic pollutants. However, due to the complex composition of radioactive organic solid waste, some organic components form complexes with radionuclides, greatly hindering the chemical reaction. This results in a large amount of incompletely decomposed organic pollutants and unseparated radionuclides remaining in the treated products. These residual pollutants not only fail to meet environmental emission or safe disposal standards but also require secondary treatment in subsequent stages. This not only increases the complexity and economic cost of the overall treatment process but also poses additional risks of pollutant leakage and diffusion during secondary treatment. Furthermore, the chemical reagents used in the chemical treatment process may react with radionuclides in unknown ways, generating more toxic byproducts, further exacerbating the uncertainty of environmental pollution and making it difficult to achieve the goal of harmless disposal of radioactive organic solid waste. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for treating radioactive organic solid waste based on ionic liquids.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for treating radioactive organic solid waste based on ionic liquids, characterized by comprising the following steps: Pretreatment and dissolution: After the radioactive organic solid waste is crushed, functionalized ionic liquid is added to form a mixed system. Temperature and pressure are controlled, and stirring is used to fully dissolve the organic solid waste. Catalytic oxidation mineralization: A catalyst and an oxidant are added to the mixture and transferred to a catalytic oxidation reactor. The mixture is then reacted under certain temperature and pressure conditions to mineralize the organic components into CO2 and H2O. Radionuclide separation: Radionuclides are separated from the reaction system using selective extraction or ion exchange methods. The separated solid or organic phases are rich in radionuclides, as well as the purified ionic liquid phase. Ionic liquid regeneration and recycling: The purified ionic liquid phase is regenerated to remove water and low-boiling-point impurities, thereby realizing the regeneration and recycling of the ionic liquid.

[0006] Furthermore, it also includes radionuclide curing, which involves adding a curing agent to the separated solid or organic phase rich in radionuclides, stirring thoroughly to make it uniform, pouring it into a mold, and curing it for a period of time under certain temperature and humidity conditions, thereby achieving the curing of radionuclides by utilizing the adsorption and encapsulation effects of the curing agent.

[0007] Furthermore, the cations of the functionalized ionic liquid include imidazoles, pyridines, or quaternary ammonium salts containing sulfonic acid groups, carboxyl groups, or hydroxyl groups, and the anions include [BF4]. - [PF6] - Or [NTf2] - .

[0008] Furthermore, the catalyst is supported on mesoporous SiO2, Al2O3 or activated carbon and loaded with transition metal oxides or noble metals, or functionalized ionic liquids with catalytic oxidation activity.

[0009] Furthermore, the oxidant is H2O2, O3, O2, or air.

[0010] Furthermore, the regeneration method of the ionic liquid includes vacuum distillation or activated carbon adsorption.

[0011] Furthermore, the radioactive organic solid waste has a particle size of less than 2 mm after being crushed.

[0012] Furthermore, the dissolution temperature of the radioactive organic solid waste is 50-150℃.

[0013] Furthermore, in the process of separating radionuclides, crown ether extractants or ion exchange resins are used for cationic nuclides, and amine extractants are used for oxyanionic nuclides.

[0014] Furthermore, the crown ether extractant includes 18-crown-6, and the amine extractant includes tri-n-octylamine.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This method utilizes ionic liquid dissolution and catalytic oxidation to treat radioactive organic solid waste, simultaneously solidifying radionuclides. The process generates no secondary pollution, and the ionic liquid is recyclable, aligning with green chemistry principles. The ionic liquid, catalyst, oxidant, and radionuclide solidification method can be flexibly selected based on different waste types to meet diverse treatment needs. It possesses strong practicality and innovation.

[0016] Ionic liquids, as novel green media, possess unique properties such as low vapor pressure, non-flammability, high thermal stability, good solubility, and ionic conductivity, demonstrating application potential in multiple fields. They exhibit excellent solubility for organic materials, such as plastics and cellulose, and under certain conditions, can convert solid organic materials into liquid hydrocarbons. Furthermore, catalytic oxidation can achieve the mineralization of liquid organic matter. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0018] To enhance understanding of the present invention, we will now describe it in further detail with reference to the accompanying drawings. These embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0019] like Figure 1 As shown, a specific embodiment of a method for treating radioactive organic solid waste based on ionic liquids includes the following steps: (1) Selection of ionic liquids Ionic liquids with specific structures and properties are selected to ensure they possess excellent solubility for the main components of radioactive organic solid waste. Furthermore, they exhibit high chemical stability, minimizing adverse reactions with radionuclides during treatment, thus ensuring the safety and stability of the process. (2) Pretreatment and dissolution First, the radioactive organic solid waste is pre-treated by crushing to achieve a particle size of less than 2 mm. Then, the crushed solid waste is added to a sealed dissolution vessel containing a selected ionic liquid.

[0020] During the dissolution process, the temperature is controlled within the range of 50-150℃. This temperature range can ensure the activity of the ionic liquid while avoiding potential risks caused by excessively high temperatures. At the same time, stirring is carried out for 1-3 hours to allow the solid waste components to fully diffuse and dissolve in the ionic liquid, ultimately forming a uniform and stable solution system.

[0021] (3) Catalytic oxidation mineralization A suitable catalyst, or alternatively, an ionic liquid with catalytic activity, is added to the solution obtained after the dissolution step. Then, oxygen or air is introduced as an oxidant, and the mixture is transferred to a dedicated catalytic oxidation reactor. Within this reactor, the reaction temperature and pressure are controlled to promote the oxidation reaction between the organic components dissolved in the ionic liquid and the oxidant, ultimately resulting in carbon dioxide and water. The carbon dioxide and water vapor produced are expelled from the reaction system with the gas flow and subsequently separated from the system through condensation, absorption, or other methods. (4) Radionuclide separation Radionuclides are separated using selective extraction or ion exchange methods. For cationic nuclides such as cesium and strontium, crown ether extractants (such as 18-crown-6) or ion exchange resins are added; for oxyanionic nuclides such as uranium and plutonium, amine extractants (such as tri-n-octylamine) are added. After separation, a solid or organic phase rich in radionuclides and a purified ionic liquid phase are obtained.

[0022] (5) Radionuclide solidification For the solid or organic phase rich in radionuclides obtained after the separation of ionic liquids, cement, bentonite and other curing agents are added, and the mixture is stirred thoroughly to make it uniform. Then it is poured into a mold and cured for a period of time under suitable temperature and humidity. The radionuclides are cured by the adsorption and encapsulation of the curing agent.

[0023] (6) Ionic liquid regeneration and circulation The purified ionic liquid phase is regenerated by removing moisture and low-boiling-point impurities through vacuum distillation at a temperature of 120-180℃ and a pressure ≤1kPa. The regenerated ionic liquid can then be recycled for the next batch of radioactive organic solid waste treatment, achieving circular utilization.

[0024] The following specific examples further illustrate this point.

[0025] Example 1: Treatment of cesium-containing radioactive waste resin (1) Pretreatment and dissolution: 20g of cesium-containing radioactive waste resin was crushed to a particle size of about 1-3mm, and 200g of functionalized ionic liquid was added. The mixture was stirred at 120℃ and 300r / min for 3h to dissolve the waste resin and form a brown solution.

[0026] (2) Catalytic oxidation mineralization: 5g of supported MnO2 / SiO2 catalyst and 100mL of 30% hydrogen peroxide solution were added to the above mixture, and the reaction was carried out at 150℃ and 1MPa for 5h. After the reaction was completed, the radioactive cesium remained in the ionic liquid phase.

[0027] (3) Separation of radionuclides: After cooling to room temperature, a chloroform solution of 18-crown-6 was added, and cesium ions were separated by liquid-liquid extraction. After repeating the extraction three times, a cesium-containing organic phase and a purified ionic liquid phase were obtained.

[0028] (4) Radionuclide solidification: A solidifying agent is added to the organic phase of cesium, and the solidification of cesium is achieved by utilizing the adsorption and encapsulation effects of the solidifying agent.

[0029] (5) Ionic liquid regeneration and recycling: The purified ionic liquid phase is distilled under reduced pressure at 150℃ and 0.5kPa for 2h to remove water and residual chloroform, and the regenerated ionic liquid is obtained for recycling.

[0030] Example 2: Treatment of uranium-containing radioactive filter paper (1) Pretreatment and dissolution: Cut 30g of uranium-containing radioactive filter paper into pieces about 2mm×2mm in size, add 300g of functionalized ionic liquid, and stir for 2h at 100℃ and 400r / min until the filter paper is basically dissolved.

[0031] (2) Catalytic oxidation mineralization: A supported Pd / Al2O3 catalyst with a Pd loading of 5 wt% was added to the solution, and O2 was introduced. The reaction was carried out at 180 °C for 6 h. After the reaction, uranium was present in the ionic liquid phase.

[0032] (3) Separation of radionuclides: A kerosene solution containing tri-n-octylamine (TOA) was added, and uranium ions were separated by liquid-liquid extraction. After extraction, a uranium-containing organic phase and a purified ionic liquid phase were obtained. (4) Radionuclide solidification: A solidifying agent is added to the uranium-containing organic phase, and the solidification of cesium is achieved by utilizing the adsorption and encapsulation effects of the solidifying agent.

[0033] (5) Regeneration and recycling of ionic liquid: The ionic liquid phase is distilled under reduced pressure at 160℃ and 0.3kPa to obtain the regenerated ionic liquid, which is then recycled.

[0034] The above specific embodiments are only for illustrating the technical concept and structural features of the present invention, and are intended to enable those skilled in the art to implement them. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and essence of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for treating radioactive organic solid waste based on ionic liquids, characterized in that, Includes the following steps: Pretreatment and dissolution: After the radioactive organic solid waste is crushed, functionalized ionic liquid is added to form a mixed system. Temperature and pressure are controlled, and stirring is used to fully dissolve the organic solid waste. Catalytic oxidation mineralization: A catalyst and an oxidant are added to the mixture and transferred to a catalytic oxidation reactor. The mixture is then reacted under certain temperature and pressure conditions to mineralize the organic components into CO2 and H2O. Radionuclide separation: Radionuclides are separated from the reaction system using selective extraction or ion exchange methods. The separated solid or organic phases are rich in radionuclides, as well as the purified ionic liquid phase. Ionic liquid regeneration and recycling: The purified ionic liquid phase is regenerated to remove water and low-boiling-point impurities, thereby realizing the regeneration and recycling of the ionic liquid.

2. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: It also includes radionuclide curing, which involves adding a curing agent to the separated solid or organic phase rich in radionuclides, stirring thoroughly to make it uniform, pouring it into a mold, and curing it for a period of time under certain temperature and humidity, thereby achieving the curing of radionuclides by utilizing the adsorption and encapsulation effect of the curing agent.

3. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: The functionalized ionic liquid's cations include imidazoles, pyridines, or quaternary ammonium salts containing sulfonic acid, carboxyl, or hydroxyl groups, and its anions include [BF4]. - [PF6] - Or [NTf2] - .

4. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: The catalyst is supported on mesoporous SiO2, Al2O3 or activated carbon and loaded with transition metal oxides or noble metals, or functionalized ionic liquids with catalytic oxidation activity.

5. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: The oxidant is H2O2, O3, O2 or air.

6. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: The regeneration methods for the ionic liquid include vacuum distillation or activated carbon adsorption.

7. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: The radioactive organic solid waste has a particle size of less than 2 mm after being crushed.

8. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: The dissolution temperature of the radioactive organic solid waste is 50-150℃.

9. The method for treating radioactive organic solid waste based on ionic liquids according to claim 1, characterized in that: In the process of separating radionuclides, crown ether extractants or ion exchange resins are used for cationic nuclides, and amine extractants are used for oxyanionic nuclides.

10. The method for treating radioactive organic solid waste based on ionic liquids according to claim 9, characterized in that: The crown ether extractant includes 18-crown-6, and the amine extractant includes tri-n-octylamine.

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