A single-atom catalyst for catalytic oxidation removal of TBP in radioactive waste liquid and a preparation method thereof

Abstract

The application discloses a single-atom catalyst for catalytic oxidation removal of TBP in radioactive waste liquid and a preparation method thereof, and comprises the following steps: S1, porous carbon material is uniformly mixed with a metal salt solution through ultrasonic stirring, and then dried under vacuum conditions, so that the metal salt is loaded on the porous carbon material; S2, the porous carbon material loaded with the metal salt is mixed with a cyanamide compound, and then subjected to low-temperature calcination at a first temperature in a protective gas environment to obtain reduced metal nanoparticles, and then subjected to high-temperature calcination at a second temperature to form a metal-carbon superstructure, and finally subjected to surface treatment to obtain the single-atom catalyst. The single-atom catalyst prepared by the application has excellent catalytic activity, which is much higher than that of existing catalysts, and can directly oxidize and degrade TBP in radioactive waste liquid into small-molecule acids, carbon dioxide and water, thereby avoiding pollution and damage to the membrane, and enabling the radioactive waste liquid to reach a level that can directly enter a membrane system for membrane treatment.

Description

Technical Field

[0001] This invention belongs to the field of radioactive wastewater treatment technology, specifically relating to a single-atom catalyst for catalytic oxidation to remove TBP from radioactive waste liquid and its preparation method. Background Technology

[0002] Currently, low- and intermediate-level radioactive waste from nuclear facilities is primarily treated using evaporation and ion exchange processes, followed by cement solidification of the resulting concentrate and waste resin. However, with the increasing scale of nuclear facility processing, the discharge of low- and intermediate-level radioactive waste has also increased significantly. Existing evaporation and ion exchange processes are becoming increasingly inadequate for large-scale radioactive waste treatment.

[0003] The high investment costs and excessive generation of secondary waste such as waste resin make it unsuitable for large-scale radioactive waste treatment. Therefore, it is necessary to adjust the large-scale treatment process for low- and intermediate-level radioactive waste, taking environmental friendliness, economic efficiency, and waste minimization as guiding principles. Appropriate treatment processes should be selected based on the characteristics of the waste liquid to further reduce investment costs, operating costs, and the amount of secondary waste generated.

[0004] Using membrane treatment technology as a pretreatment technique in evaporation processes can significantly reduce the investment and operating costs of evaporators. This process has been widely used in the civilian sector and can also be applied to the treatment of low- and intermediate-level radioactive waste. However, membranes are sensitive to organic matter in wastewater, which can cause fouling or damage. Therefore, the organic matter content in the membrane feed water must be strictly controlled. However, low- and intermediate-level radioactive waste from nuclear facilities contains high concentrations of the organic compound tributyl phosphate (TBP), making direct membrane treatment impossible without its removal.

[0005] Currently, commonly used TBP treatment technologies include biochemical technology, adsorption technology, electrocatalytic oxidation technology, and advanced oxidation technologies such as ozone catalytic oxidation and hydrogen peroxide catalytic oxidation. Since radioactive wastewater contains only TBP or small amounts of toxic organic matter such as kerosene as extractants, and does not contain carbon sources for microbial growth, and the wastewater is radioactive, it cannot provide an environment for microbial growth. Therefore, biochemical technology is unsuitable for treating organic matter in radioactive wastewater. Adsorption technology commonly uses macroporous resins or activated carbon as adsorbents. However, using adsorbents generates large amounts of regenerated wastewater and waste resin or activated carbon, significantly increasing the amount of secondary pollutants, making it unsuitable for removing organic matter from radioactive wastewater. Advanced oxidation technologies can be categorized based on the type of oxidant, including electrocatalytic oxidation, ozone catalytic oxidation, hydrogen peroxide catalytic oxidation, photocatalytic oxidation, and air catalytic oxidation. Catalysts are the core materials of this technology, but current catalysts used in advanced oxidation technologies to treat TBP-containing radioactive wastewater are insufficient to directly oxidize and degrade TBP to a level suitable for membrane treatment. Therefore, developing a catalyst that can efficiently remove organic matter is key to the successful application of advanced oxidation technology in the treatment of TBP in radioactive waste. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the existing technology by providing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid and its preparation method. The single-atom catalyst has excellent catalytic effect, which is far superior to that of existing catalysts. It can directly oxidize and degrade TBP in radioactive waste liquid into small molecule acids, carbon dioxide and water, avoiding fouling and damage to the membrane, so that the radioactive waste liquid can reach the level of being directly introduced into the membrane system for membrane treatment technology.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0008] According to a first aspect of the present invention, a method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste is provided, comprising:

[0009] S1, the porous carbon material and the metal salt solution are ultrasonically stirred and mixed, and then dried under vacuum conditions, so that the metal salt is loaded on the porous carbon material.

[0010] S2 involves thoroughly mixing porous carbon materials loaded with metal salts with cyanamide compounds, and then calcining them at a low temperature in a protective gas environment to obtain reduced metal nanoparticles. In the second temperature, the mixture is calcined at a high temperature to form a metal-carbon superstructure, which is then surface-treated to obtain a single-atom catalyst.

[0011] Preferably, the specific surface area of ​​the porous carbon material is 700–1200 m².2 / g, pore volume 0.3~0.6cm 3 / g, abrasion strength of 90-97%, and compressive strength of 30-50N.

[0012] Preferably, the porous carbon material is prepared by the following method:

[0013] The nuclear-grade ion exchange resin was subjected to hydrothermal oxidation treatment, wherein the hydrothermal oxidation temperature was 100–250℃, the pressure was 1–6MPa, and the time was 2–12h.

[0014] The porous carbon material is prepared by drying the nuclear-grade ion exchange resin after hydrothermal oxidation treatment and then performing high-temperature carbonization treatment in an inert environment. The high-temperature carbonization temperature is 600-1100℃ and the time is 2-12h.

[0015] Preferably, the nuclear-grade ion exchange resin is an anion exchange resin or a cation exchange resin, and the nuclear-grade ion exchange resin has a sphericity greater than 90%, a uniformity coefficient ≤ 1.2, and a particle size variation range of ± 0.100 mm.

[0016] Preferably, the metal salt solution is an aqueous chloride solution of a transition metal, wherein the transition metal is one or more of copper, iron, nickel, and cerium, and the loading amount of the metal salt on the porous carbon material is 0.2-4.0 wt.%, wherein the loading amount is expressed as the ratio of the mass of the transition metal element to the mass of the carrier.

[0017] Preferably, the mass ratio of the porous carbon material loaded with metal salt to the cyanamide compound is 1:(0.2-3).

[0018] Preferably, the first temperature is 200-500℃, the calcination time is 3-8h, and the heating rate is 3-8℃ / min; the second temperature is 800-1200℃, the calcination time is 2-5h, and the heating rate is 3-8℃ / min.

[0019] Preferably, the surface treatment includes:

[0020] First, high-temperature acid washing and immersion are used to remove residual metal nanoclusters on the surface, then the solution is eluted to neutral, and then dried.

[0021] The conditions for high-temperature pickling and soaking are as follows: use 1.0-2.0 mol / L H2SO4 or hydrochloric acid solution, and treat for 5-10 hours at 70-150℃ under normal or pressurized nitrogen atmosphere.

[0022] According to a second aspect of the present invention, a single-atom catalyst for catalytic oxidation to remove TBP from radioactive waste is provided, which is prepared by the preparation method described above.

[0023] Preferably, the single-atom catalyst has a particle size of 0.3–1.2 mm and a specific surface area of ​​600–1000 m². 2 / g, pore volume 0.2~0.5cm 3 / g, abrasion strength of 90-97%, and compressive strength of 38-45N.

[0024] Beneficial effects:

[0025] This invention relates to a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste and its preparation method. The preparation method is simple, uses readily available raw materials, and the single-atom catalyst exhibits high catalytic activity and excellent catalytic effect, far exceeding that of existing catalysts. When used for the catalytic oxidation removal of tributyl phosphate (TBP) from radioactive waste, TBP can achieve 100% mineralization, decomposing into carbon dioxide, water, and a small amount of small-molecule acids. This allows the radioactive waste to reach a level suitable for direct treatment using membrane systems, thus avoiding membrane fouling and damage. Furthermore, the single-atom catalyst demonstrates good stability, long service life, and low secondary waste generation, reducing the amount of solid waste disposal. This benefits both environmental protection and lowers disposal costs, making it highly suitable for TBP removal from radioactive waste. In addition, the raw material for the catalyst support is nuclear-grade resin, allowing for the disposal of spent catalysts along with other spent resins. The treatment process is mature and requires no additional equipment, facilitating its widespread application in nuclear facility waste. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the preparation method of a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid according to an embodiment of the present invention.

[0027] Figure 2 The figures show the results of performance tests ③ and ④ in this embodiment of the invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0029] Example 1

[0030] This embodiment discloses a method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, comprising:

[0031] S1, after mixing the porous carbon material and the metal salt solution by ultrasonic stirring, the mixture is dried under vacuum conditions, so that the metal salt is loaded onto the porous carbon material. The porous carbon material serves as a catalyst support, and the metal salt provides the metal elements required for the active components in the catalyst.

[0032] S2 involves thoroughly mixing porous carbon materials loaded with metal salts with cyanamide compounds in a specific ratio. Under a protective gas environment, the mixture is first calcined at a low temperature to obtain reduced metal nanoparticles, and then calcined at a high temperature to form a metal-carbon superstructure (denoted as the MC superstructure, where M represents metal). After surface treatment, a single-atom catalyst with the MC superstructure is obtained. This MC superstructure possesses a hierarchical porous structure and a high distribution of metal active sites, resulting in extremely high catalytic activity in catalytic oxidation technologies.

[0033] In some embodiments, the specific surface area of ​​the porous carbon material is preferably 700–1200 m². 2 / g, with a pore volume preferably of 0.3–0.6 cm³. 3 / g. More preferably, the porous carbon material also has good wear strength and compressive strength, with the wear strength preferably being 90-97% and the compressive strength preferably being 30-50N.

[0034] In some embodiments, the porous carbon material is prepared using nuclear-grade ion exchange resin as raw material, and is obtained through hydrothermal oxidation-high-temperature carbonization, specifically including the following steps:

[0035] (1) The nuclear-grade ion exchange resin is subjected to hydrothermal oxidation treatment, wherein the hydrothermal oxidation adopts air wet oxidation, the hydrothermal oxidation temperature is 100-250℃, and typical but non-limiting hydrothermal oxidation temperatures can be 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, 220℃ and 250℃, the pressure is 1-6MPa, and typical but non-limiting hydrothermal oxidation pressures can be 1MPa, 2MPa, 3MPa, 4MPa, 5MPa and 6MPa, and the time is 2-12h;

[0036] (2) The nuclear-grade ion exchange resin after hydrothermal oxidation is dried and then subjected to high-temperature carbonization in an inert environment to obtain the porous carbon material. The high-temperature carbonization temperature is 600-1100℃, and typical but non-limiting high-temperature carbonization temperatures can be 600℃, 700℃, 800℃, 900℃, 1000℃ and 1100℃, and the time is 2-12h.

[0037] In some embodiments, the nuclear-grade ion exchange resin can be an anion exchange resin or a cation exchange resin. The nuclear-grade ion exchange resin preferably has a sphericity greater than 90%, a uniformity coefficient preferably ≤1.2, a particle size variation range of ±0.100 mm, wherein particles smaller than 0.3 mm do not exceed 0.2% of the total volume, and an average crushing strength ≥350 g / particle, to ensure that the catalyst has high strength and uniform particle size, thereby improving the efficiency of the catalytic oxidation reaction.

[0038] In some embodiments, the metal salt solution is preferably a chloride solution of a transition metal, and the active component in this catalyst is a transition metal. More preferably, the transition metal is one or more divalent transition metals such as copper, iron, nickel, and cerium, and its chloride is represented as MCl2. The loading amount of the metal salt on the porous carbon material (i.e., the mass ratio of the metal element to the porous carbon material support) is 0.2-4.0 wt.%.

[0039] In some embodiments, the mass ratio of the porous carbon material loaded with metal salt to the cyanamide compound is 1:(0.2-3). In this embodiment, the cyanamide compound is preferably dicyandiamide.

[0040] In some embodiments, the protective gas environment in step S2 is preferably a nitrogen environment.

[0041] In some embodiments, the first temperature is 200-500℃, typically but not limitingly, it can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, and 500℃, with a calcination time of 3-8 hours and a heating rate of 3-8℃ / min; the second temperature is 800-1200℃, typically but not limitingly, it can be 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, and 1200℃, with a calcination time of 2-5 hours and a heating rate of 3-8℃ / min. The heating rate controlled at 3-8℃ / min in this method ensures the dispersion of the active components of the catalyst, thereby guaranteeing the catalytic effect. The selection of the calcination temperature ensures both the strength of the catalyst and the bonding strength between the active components and the support, preventing the active components from leaching from the support surface during the reaction and extending the catalyst's lifespan.

[0042] In some embodiments, the surface treatment includes the following steps:

[0043] The MC superstructure sample was first subjected to high-temperature acid washing to remove residual metal nanoclusters on the surface. The sample was then eluted to neutral pH and subsequently dried. The preferred conditions for high-temperature acid washing were: 1.0-2.0 mol / L H₂SO₄ or hydrochloric acid solution, treated at 70-150℃ under normal or pressurized nitrogen atmosphere for 5-10 hours to remove residual metal nanoparticles or clusters from the sample surface.

[0044] This embodiment also discloses a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which is prepared by the preparation method described above.

[0045] In some embodiments, the single-atom catalyst has uniform particle size, preferably 0.3–1.2 mm; high strength, preferably 90–97% abrasion strength and 38–45 N compressive strength; and large specific surface area, preferably 600–1000 m². 2 / g, pore volume 0.2~0.5cm 3 / g.

[0046] The method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid in this invention embodiment is simple, uses readily available raw materials, and yields a single-atom catalyst with high catalytic activity and excellent catalytic effect, far exceeding that of existing catalysts. When used for the catalytic oxidation removal of tributyl phosphate (TBP) from radioactive waste liquid, TBP can achieve 100% mineralization, decomposing into carbon dioxide, water, and a small amount of small-molecule acids. This allows the radioactive waste liquid to be directly treated using membrane systems, thus avoiding membrane fouling and damage. Furthermore, this single-atom catalyst exhibits good stability, long service life, and low secondary waste generation, reducing the amount of solid waste disposal. This benefits both environmental protection and lowers disposal costs, making it highly suitable for TBP removal from radioactive waste liquid. In addition, the raw material for the support of this single-atom catalyst is nuclear-grade resin, allowing for the disposal of spent catalysts along with other spent resins. The treatment process is mature and requires no additional equipment, facilitating its widespread application in nuclear facility waste liquid treatment.

[0047] The following are several specific preparation examples to illustrate the single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid and its preparation method in the embodiments of the present invention, as detailed below:

[0048] Preparation Example 1

[0049] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid includes the following steps:

[0050] (1) Place 100g of nuclear-grade cation exchange resin and 200mL of deionized water in a hydrothermal oxidation reactor, fill with oxygen to maintain the pressure inside the reactor at 6MPa, raise the temperature to 200℃, maintain the constant temperature, perform hydrothermal oxidation for 6h, cool down and take it out, dry it at 120℃, and then place it in an atmosphere muffle furnace and calcine it at 800℃ in a nitrogen atmosphere for 6h (i.e., high-temperature carbonization treatment) to obtain porous carbon material used as a catalyst support.

[0051] (2) The prepared porous carbon material for catalyst support is mixed evenly with a mixed solution of ferric chloride and cerium chloride, wherein the amount of iron is added at 2% of the catalyst ratio and the amount of cerium is added at 0.2% of the catalyst ratio; then, it is ultrasonically stirred at 50°C under vacuum for 6 hours, and then placed in a vacuum drying oven to dry, thereby obtaining the porous carbon material loaded with ferric chloride and cerium chloride.

[0052] (3) The carbon porous material loaded with metal salt was mixed with dicyandiamide at a mass ratio of 1:1 and calcined at 400℃ (i.e., the first temperature) for 5 hours in a nitrogen atmosphere (i.e., low temperature calcination) with a heating rate of 6℃ / min. Then, it was calcined at 1000℃ (i.e., the second temperature) in a nitrogen atmosphere for 3 hours (i.e., high temperature calcination) to obtain a sample with MC superstructure.

[0053] (4) The sample with the MC superstructure was immersed in 1.0 mol / L H2SO4 solution at 80°C under a nitrogen atmosphere for 8 hours to remove the residual Ni nanoparticles or clusters on the surface. Then, it was rinsed with deionized water until neutral and then dried in an oven at 120°C to obtain a single-atom catalyst named FeC-1.

[0054] Preparation Example 2

[0055] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0056] In Preparation Example 2, a nuclear-grade anion exchange resin was used instead of the nuclear-grade cation exchange resin in Preparation Example, and the resulting single-atom catalyst was named FeC-1.

[0057] Preparation Example 3

[0058] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0059] The hydrothermal oxidation temperature was 120℃, the hydrothermal oxidation time was 4h, the high-temperature carbonization temperature was 600℃, the high-temperature carbonization time was 4h, and the obtained single-atom catalyst was named FeC-3.

[0060] Preparation Example 4

[0061] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0062] The hydrothermal oxidation temperature was 250℃, the hydrothermal oxidation time was 2h, the high-temperature carbonization temperature was 1100℃, the high-temperature carbonization time was 1h, and the obtained single-atom catalyst was named FeC-4.

[0063] Preparation Example 5

[0064] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0065] The active component iron was added at a rate of 3.5% of the catalyst ratio, and cerium was added at a rate of 0.5% of the catalyst ratio. The resulting single-atom catalyst was named FeC-5.

[0066] Preparation Example 6

[0067] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0068] The single-atom catalyst prepared by using a carbon porous material loaded with ferric chloride and cerium chloride in a mass ratio of 1:0.2 to dicyandiamide was named FeC-6.

[0069] Preparation Example 7

[0070] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0071] The single-atom catalyst prepared by loading ferric chloride and cerium chloride onto a porous carbon material with a mass ratio of 1:3 to dicyandiamide was named FeC-7.

[0072] Preparation Example 8

[0073] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0074] The first temperature was 500℃ and the calcination time was 3h; the second temperature was 1200℃ and the calcination time was 2h; the obtained single-atom catalyst was named FeC-8.

[0075] Preparation Example 9

[0076] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0077] The first temperature was 200℃, and the calcination time was 6 hours; the second temperature was 800℃, and the calcination time was 5 hours; the obtained single-atom catalyst was named FeC-9.

[0078] Preparation Example 10

[0079] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0080] In Preparation Example 10, a 2.0 mol / L hydrochloric acid solution was used instead of the 1.0 mol / L H2SO4 solution in Preparation Example 1, and the resulting single-atom catalyst was named FeC-10.

[0081] Preparation Example 11

[0082] A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, which differs from Preparation Example 1 in that:

[0083] In Preparation Example 11, a mixed solution of copper chloride, nickel chloride, and cerium chloride was used instead of the mixed solution of ferric chloride and cerium chloride in Preparation Example 1. That is, the active components were Cu, Ni, and Ce. Iron was added at 2% of the catalyst ratio, nickel at 1% of the catalyst ratio, and cerium at 0.2% of the catalyst ratio. The resulting single-atom catalyst was named CuC-1.

[0084] Performance test experiment ①

[0085] Radioactive wastewater was simulated using a TBP-simulated feed solution with a TBP concentration of 150 mg / L, a TOC (total organic carbon) concentration of 81 mg / L, a sodium nitrate concentration of 25 g / L, and a neutral pH. Equal amounts of the single-atom catalysts prepared in Examples 1-11 of this invention, as well as purchased alumina-based catalysts (named Al-C), activated carbon-based catalysts (named AC-C), and silicon-aluminum-based catalysts (named Si-C), were used for ozone catalytic treatment of the above-mentioned TBP-simulated feed solution wastewater. The mass ratio of ozone to TBP was 1:1, and the hydraulic residence time of the catalyst (i.e., the contact reaction time between the wastewater and the catalyst) was 30 min. After 8 hours of continuous and stable operation, samples were taken to detect the removal rates of TBP and TOC. The experimental results are shown in Table 1.

[0086] Table 1 Results of Performance Test ①

[0087]

[0088] As can be seen from Table 1, the single-atom catalysts prepared by the invention preparation examples 1 to 11 have excellent catalytic effects when used for ozone catalytic oxidation to remove TBP from waste liquid. TBP removal is 100% achieved, and the TOC removal rate is over 92%, which is far higher than the catalytic effect of existing commercial catalysts.

[0089] Performance test experiment ②

[0090] The difference between this performance test ② and performance test ① is that the simulated TBP wastewater used for ozone catalytic removal treatment was replaced with the simulated TBP wastewater used for hydrogen peroxide catalytic removal treatment. The test results are shown in Table 2.

[0091] Table 2 Results of Performance Test ②

[0092]

[0093] As can be seen from Table 2, the single-atom catalysts prepared by Examples 1 to 11 of the present invention have excellent catalytic effects when used for the catalytic oxidation of hydrogen peroxide to remove TBP from waste liquid. TBP removal is 100% achieved, and the TOC removal rate is over 90%, which is far superior to the catalytic effect of existing commercial catalysts.

[0094] Performance test experiment ③

[0095] The single-atom catalyst prepared in Example 1 of this invention was used to treat TBP-simulated feed wastewater to investigate the catalyst's lifespan. The composition and reaction conditions of the TBP-simulated feed were the same as in performance test ①, except that performance test ③ was run continuously for 15 days to examine the catalyst's stability. The test results are as follows: Figure 2 As shown.

[0096] Performance test experiment ④

[0097] The test conditions and objectives of this performance test are the same as those of performance test ③, the difference being:

[0098] Performance test ③ was used for ozone catalytic removal of the aforementioned TBP simulated wastewater, while performance test ④ was used for hydrogen peroxide catalytic removal of the aforementioned TBP simulated wastewater. The test results are as follows: Figure 2 As shown.

[0099] Depend on Figure 2 It can be seen that the single-atom catalyst prepared by the method of the present invention, when used for ozone catalytic oxidation and hydrogen peroxide catalytic oxidation to remove TBP from waste liquid, did not show a decrease in catalytic activity after 15 days of continuous operation, indicating that the catalyst has good stability and a long service life.

[0100] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, comprising: S1, the porous carbon material and the metal salt solution are ultrasonically stirred and then dried under vacuum, so that the metal salt is loaded onto the porous carbon material. The porous carbon material is prepared by hydrothermal oxidation-high temperature carbonization using nuclear-grade ion exchange resin as raw material. The specific surface area of ​​the porous carbon material is 700~1200 m². 2 / g, pore volume 0.3~0.6cm 3 / g; S2, porous carbon material loaded with metal salt is thoroughly mixed with cyanamide compounds, and under a protective gas environment, it is first calcined at a low temperature at a first temperature to obtain reduced metal nanoparticles, and then calcined at a high temperature at a second temperature to form a metal-carbon superstructure. After surface treatment, a single-atom catalyst is obtained. The first temperature is 200-500℃, the calcination time is 3-8h, and the heating rate is 3-8℃ / min; the second temperature is 800-1200℃, the calcination time is 2-5h, and the heating rate is 3-8℃ / min; the surface treatment includes first removing residual metal nanoclusters on the surface by high-temperature acid washing and immersion, then eluting to neutral, and then drying. The conditions for high-temperature pickling and soaking are as follows: using 1.0~2.0 mol / L H2SO4 or hydrochloric acid solution, at 70~150℃, under normal pressure or pressurized nitrogen atmosphere for 5~10 hours.

2. The method for preparing the single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid according to claim 1, characterized in that, The compressive strength of the porous carbon material is 30~50N.

3. The method for preparing the single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid according to claim 1, characterized in that, The porous carbon material is prepared by the following method: The nuclear-grade ion exchange resin is subjected to hydrothermal oxidation treatment, wherein the hydrothermal oxidation temperature is 100~250℃, the pressure is 1~6MPa, and the time is 2~12h. The porous carbon material is prepared by drying the nuclear-grade ion exchange resin after hydrothermal oxidation treatment and then performing high-temperature carbonization treatment in an inert environment. The high-temperature carbonization temperature is 600~1100℃ and the time is 2~12h.

4. The method for preparing the single-atom catalyst for catalytic oxidation removal of TBP from radioactive waste liquid according to claim 3, characterized in that, The nuclear-grade ion exchange resin has a sphericity greater than 90%, a uniformity coefficient ≤ 1.2, and a particle size variation range of ±0.100 mm.

5. The method for preparing the single-atom catalyst for catalytic oxidation removal of TBP from radioactive waste liquid according to claim 1, characterized in that, The metal salt solution is a chloride solution of a transition metal, wherein the transition metal is one or more of copper, iron, nickel, and cerium, and the loading amount of the metal salt on the porous carbon material is 0.2-4.0 wt.%.

6. The method for preparing the single-atom catalyst for catalytic oxidation removal of TBP from radioactive waste liquid according to claim 1, characterized in that, The mass ratio of porous carbon material loaded with metal salt to cyanamide compound is 1:(0.2~3).

7. A single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.

8. The single-atom catalyst for the catalytic oxidation removal of TBP from radioactive waste liquid according to claim 7, characterized in that, The single-atom catalyst has a particle size of 0.3~1.2 mm and a specific surface area of ​​600~1000 m². 2 / g, pore volume 0.2~0.5cm 3 / g, with a compressive strength of 38~45N.

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