An electrochemical uranium extraction system and a method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction.

Abstract

This invention discloses an electrochemical uranium extraction system and a method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction, comprising: Step 1, synthesizing MoO x Nanosheets; Step 2: Using a uranium source and the MoO prepared in Step 1 x U-MoO was synthesized using nanosheets as raw materials. x Nanosheets. This invention successfully introduces isolated uranyl into MoO. x Nanosheets were used to extract uranium from uranium-containing wastewater, achieving highly efficient electrochemical reduction and deposition of uranium in fluorine-containing wastewater. During electrolysis, isolated uranyl-MoO₂... x This creates an interfacial hydrogen spillover effect, enabling the regeneration of uranium active sites and ensuring the continuous reduction and deposition of uranyl. Furthermore, when combined with an electrochemical uranium extraction system, it can also achieve uranium extraction in seawater or other uranium-containing wastewater.

Description

Technical Field

[0001] This invention belongs to the field of uranium-containing wastewater treatment technology. More specifically, this invention relates to an electrochemical uranium extraction system and a method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction. Background Technology

[0002] Uranium is a key nuclear fuel in nuclear power plants, and fluoride- and uranium-containing wastewater is generated during the conversion and enrichment steps of the fuel cycle. Currently, nuclear fuel enrichment mainly relies on gas centrifugation, which converts uranium into gaseous uranium hexafluoride molecules, achieving enrichment and separation of uranium in a high-speed centrifuge. Therefore, fluoride- and uranium-containing wastewater is generated during the production of uranium enrichment plants and nuclear fuel (assembly) manufacturing plants. The main sources are process tail gas scrubbing fluid, acid mist purification tower scrubbing fluid in exhaust purification centers, container cleaning fluid, accident cleaning fluid, and waste liquid generated from equipment maintenance. Fluoride- and uranium-containing wastewater poses a certain degree of environmental harm and must be effectively treated before discharge. The state has strict discharge standards for fluoride- or uranium-containing wastewater: the uranium concentration in the discharged wastewater must not exceed 0.05 mg / L, and the fluoride concentration must not exceed 10 mg / L. Therefore, it is crucial to extract and recycle uranium from fluoride- and uranium-containing wastewater during the nuclear fuel cycle. Currently, the domestic process for treating fluoride- and uranium-containing wastewater mainly relies on the traditional method of ammonium salt precipitation combined with adsorption. Traditional processes are cumbersome, inefficient, and have low adsorption capacity. Therefore, there is a need to develop a new, low-cost, simple, green, and efficient method for extracting uranium from fluoride- and uranium-containing wastewater. Compared with traditional methods, electrochemical uranium extraction has significant advantages. The electrochemical method uses an external electric field, F... - CO3 2- Anions migrate towards the anode via coulombic action, reducing the interference of fluoride ions on the reduction and extraction of uranium. Simultaneously, uranyl ions accumulate at the cathode and are reduced to uranium oxide, which is deposited on the electrode surface. Furthermore, the electrochemical adsorption kinetics are faster, the extraction concentration range is wider, and it is not limited by adsorption capacity. Research on high-efficiency electrochemical uranium recovery technology from fluorine-containing uranium solutions has significant social and economic benefits. Novel electrochemical adsorption materials can effectively improve production efficiency, reduce production costs, save labor and material expenses, and generate less solid waste, thus reducing subsequent waste treatment costs and generating significant economic benefits for nuclear plants. Moreover, by reducing uranium through high-efficiency electrochemical adsorption, it is easier to recover and utilize uranium from depleted uranium materials, conserving uranium resources, reducing uranium mining, and possessing potential economic benefits for the future development of nuclear power. Summary of the Invention

[0003] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0004] To achieve these objectives and other advantages according to the present invention, a method for preparing electrochemically extracted molybdenum oxide-based nanosheets is characterized by comprising the following steps:

[0005] Step 1: Synthesis of MoO x Nanosheets, x < 3;

[0006] Step 2: Using a uranium source and the MoO prepared in Step 1 x U-MoO was synthesized using nanosheets as raw materials. x Nanosheets.

[0007] Preferably, in step one, MoO is synthesized. x The methods for nanosheets include:

[0008] Molybdenum metal powder was mixed with 1-butanol, and then hydrogen peroxide was added. The mixture was stirred for a certain period of time to form a pure yellow solution. The final solution was transferred to an autoclave, heated and kept at that temperature for a certain period of time, and the precipitate was concentrated by centrifugation. The precipitate was washed several times with anhydrous ethanol and deionized water, and then dried overnight to obtain MoO2. x Nanosheets.

[0009] Preferably, the molybdenum metal powder, 1-butanol, and hydrogen peroxide are used in a ratio of 1-6 mmol: 12-80 mL: 1-10 mL, and the mass fraction of hydrogen peroxide is 10-40 wt%.

[0010] Preferably, the stirring time after adding hydrogen peroxide is 10-60 min, the heating temperature of the autoclave is 120-180℃, the holding time is 6-24 h, and the overnight drying temperature is 40-80℃.

[0011] Preferably, in step two, U-MoO is synthesized. x The methods for nanosheets include:

[0012] Will MoO x Nanosheets and UO2(NO3)2·6H2O were dispersed in deionized water, and photocatalysis was performed for a certain period of time to ensure the fixation and reduction of uranyl. After the reaction was completed, the precipitate was concentrated by centrifugation and dried overnight at a certain temperature to obtain U-MoO2. x Nanosheets.

[0013] Preferably, MoO x The mass-to-volume ratio of nanosheets, UO2(NO3)2·6H2O and deionized water is 50–200 mg: 1–15 mg: 5–30 mL.

[0014] Preferably, the photocatalytic time is 1–12 h and the overnight drying temperature is 40–80 °C.

[0015] A U-MoO with electrochemical uranium extraction function x Application of nanosheets, the U-MoO x Nanosheets are used for the extraction of uranium from uranium-containing wastewater.

[0016] Preferably, the U-MoO x Experimental methods for applying nanomaterials to electrochemical uranium extraction include: using an electrochemical workstation with Ag / AgCl and Pt wires as the reference and counter electrodes, respectively, and preparing a 3.5M potassium chloride solution as the electrolyte; and adding U-MoO... x Nanomaterial samples, carbon black, and a 0.5 wt% Nafion solution were dissolved in alcohol and ultrasonically treated for 0.5 h to obtain a uniform ink containing U-MoO. x The mass-to-volume ratio of nanomaterial sample, carbon black, Nafion solution, and alcohol was 1–10 mg: 1–10 mg: 10–70 μL: 1–8 mL; then, the ink was brushed onto 1 × 2 cm carbon paper as the working electrode, and the U-MoO was subjected to potentiostatic method. x The reducing power of nanomaterials on U(VI) was determined.

[0017] An electrochemical uranium extraction system, the structure of which includes:

[0018] A floating plate with a PVC fixed mesh tube on its upper surface, on which a solar panel is laid;

[0019] An electrode pool is located below the float plate and is connected to the PVC fixed mesh pipe by a steel wire rope. The upper and lower ends of the electrode pool are respectively provided with water inlets, and an aluminum plate is installed in the water inlet. The aluminum plate is provided with multiple small holes. The top of the electrode pool is provided with multiple exhaust ports, and the exhaust ports are connected to the atmosphere through flexible hoses.

[0020] The electrode cell is externally equipped with a counterweight mechanism, which includes:

[0021] A base plate is disposed at the bottom of the electrode cell;

[0022] A top plate is disposed at the upper end of the electrode pool, a connecting column is connected between the bottom plate and the top plate, and the steel wire rope is detachably connected to the top plate;

[0023] The electrode cell is internally provided with a platinum electrode, a first cathode plate and a second cathode plate, wherein the first cathode plate and the second cathode plate are connected by a tin bronze plate.

[0024] The solar panel is connected to a controller, which is connected to a battery for energy storage and a pure sine wave inverter. The pure sine wave inverter is connected to a high-frequency power supply. The platinum electrode, the first cathode plate, and the second cathode plate are connected to the high-frequency power supply via cables.

[0025] Carbon paper is disposed on the first cathode plate and the second cathode plate, and the carbon paper is coated with ink. The method for preparing the ink includes: U-MoO x Nanosheet samples, carbon black, and a 0.5 wt% Nafion solution were dissolved in alcohol and ultrasonically treated for 0.5 h to obtain a uniform ink containing U-MoO. x The mass-to-volume ratio of nanosheet sample, carbon black, Nafion solution and alcohol was 1–10 mg: 1–10 mg: 10–70 μL: 1–8 mL.

[0026] This invention includes at least the following beneficial effects: This invention successfully introduces isolated uranyl into MoO. x Nanosheets enabled highly efficient electrochemical reduction and deposition of uranium in fluoride- and uranium-containing wastewater. (3 g / LF) - Under conditions of coexistence with 100 ppm uranium, U-MoO x The nanosheet uranium extraction efficiency reached 95.26%, and 7.13 mg of uranium was desorbed within two hours after applying a positive voltage of 1.5V. In solution systems with different fluorine-to-uranium ratios, U-MoO₂… x The extraction efficiency of uranyl was maintained at 90%. U-MoO x It exhibits good cycling stability in multiple U(VI) capture test cycles and demonstrates excellent resistance to ion interference. In uranium enrichment experiments, yellow uranium oxide was extracted with an adsorption capacity as high as 2382 mg / g. The introduction of isolated uranyl with MoO x An interfacial bond structure is formed between them, which lowers the reduction potential of uranyl. During electrolysis, isolated uranyl-MoO x This creates an interfacial hydrogen spillover effect, enabling the regeneration of uranium active sites and ensuring the continuous reduction and deposition of uranyl.

[0027] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0028] Figure 1 MoO prepared in Example 1 x TEM image of nanosheets;

[0029] Figure 2 U-MoO prepared in Example 1 x TEM image of nanosheets;

[0030] Figure 3 U-MoO prepared in Example 1 x EDX elemental mapping image of nanosheets;

[0031] Figure 4 MoO prepared in Example 1 x Nanosheets and U-MoO x XRD patterns of nanosheets;

[0032] Figure 5 MoO prepared in Example 1 x Nanosheets and U-MoO x O1s XPS spectra of nanosheets;

[0033] Figure 6 MoO prepared in Example 1 x Nanosheets and U-MoO x ESR spectrum of nanosheets;

[0034] Figure 7 For 100ppm U(VI) and 3000ppm F - Under coexistence conditions, MoO x Nanosheets and U-MoO x The extraction efficiency of uranium from nanosheets;

[0035] Figure 8 For 50ppm U(VI) and 3000ppm F - Under coexistence conditions, MoO x Nanosheets and U-MoO x The extraction efficiency of uranium from nanosheets;

[0036] Figure 9 for U-MoO x Physicochemical adsorption capacity diagram of nanosheets;

[0037] Figure 10 for U-MoO x Resolution efficiency of nanosheets;

[0038] Figure 11 The time-current curves for electrochemical uranium desorption are shown.

[0039] Figure 12 For 100ppm and 3000ppm F - Under coexistence conditions, U-MoO x Nanosheet cycling performance testing;

[0040] Figure 13 For different fluorine-uranium ratios U-MoO xPerformance testing of nanosheets;

[0041] Figure 14 U-MoO at different pH values x Performance testing of nanosheets;

[0042] Figure 15 Performance testing of U-MoO under single anion interference x Performance testing of nanosheets;

[0043] Figure 16 Optical photographs before and after uranium extraction;

[0044] Figure 17 for U-MoO x and MoO x Linear voltammetric scan curves of nanosheets in the presence of uranium;

[0045] Figure 18 for U-MoO x Nanosheets and MoO x O1s XPS spectrum of uranium electroreduction from nanosheets;

[0046] Figure 19 for U-MoO x Nanosheets and MoO x ESR after uranium electroreduction by nanosheets;

[0047] Figure 20 for U-MoO x Nanosheets and MoO x Temperature-programmed reduction curve of nanosheets;

[0048] Figure 21 To determine the U-MoO in the presence of 0.5M sodium sulfate x Nanosheets and MoO x Linear voltammetric scan curves of nanosheets;

[0049] Figure 22 To achieve U-MoO₂ under conditions of coexistence with 8 ppm uranium in light or heavy water x Adsorption kinetics of uranium;

[0050] Figure 23 This is an elemental diagram of U-MoOx nanosheets after uranium extraction.

[0051] Figure 24 The U 4f XPS spectrum of U-MoOx nanosheets after uranium extraction;

[0052] Figure 25 XRD patterns of U-MoOx nanosheets after uranium extraction;

[0053] Figure 26A schematic diagram of the electrochemical uranium extraction system;

[0054] Figure 27 This is a schematic diagram of the electrode cell structure;

[0055] Figure 28 This is a schematic diagram of the cross-sectional structure of the electrode cell;

[0056] Figure 29 This is a schematic diagram of the internal structure of the electrode cell. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0058] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0059] Example 1

[0060] This embodiment provides a method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction, comprising the following steps:

[0061] Step 1: Synthesize MoO using a solvothermal process x Nanosheets: 2 mmol of molybdenum metal powder was mixed with 24 mL of 1-butanol in a 50 mL beaker, then 3 mL of hydrogen peroxide (30 wt%) was added, and the mixture was stirred for 30 min to form a pure yellow solution. The final solution was transferred to a 50 mL autoclave and kept at 140 °C for 12 hours. The precipitate was then concentrated by centrifugation, washed three times with anhydrous ethanol and deionized water, and then dried overnight at 60 °C to obtain MoO2 nanosheets. x Nanosheets;

[0062] Step 2: Preparation of U-MoO by low-temperature photoreduction method x Nanosheets: 100mg MoO x Nanosheets and 6 mg of UO2(NO3)2·6H2O were dispersed in 10 mL of deionized water, and photocatalysis was performed for 3 h to ensure the fixation and reduction of uranyl. After the reaction, the precipitate was concentrated by centrifugation and dried overnight at 60 °C to obtain U-MoO2. x Nanosheets.

[0063] Electrochemical experiments were conducted using an electrochemical workstation (CHI 760E electrochemical analyzer) and a three-electrode system. Ag / AgCl and Pt wire were used as the reference and counter electrodes, respectively, and a 3.5M potassium chloride solution was used as the electrolyte. Before the experiment, 5 mg of U-MoO2 was added... xNanosheet samples, 3 mg carbon black, and 35 μL Nafion solution (0.5 wt%) were dissolved in 2 mL of alcohol and sonicated for 0.5 h to obtain a uniform ink. The solution was then brushed onto a 1 × 2 cm carbon felt. Electrochemical performance was tested using a potentiostatic method with specific voltage parameters. Linear sweep voltammetry (LSV) curves of U(VI) reduction in 0.5 Na₂SO₄ electrolyte containing U(VI) were obtained. The scan rate was 2 mV / s, and the potential window range was 0 V to -1 V. UO₂ was determined using UV-Vis spectrophotometry at 651.8 nm and ICP-OES (inductively coupled plasma optical emission spectrometry). 2+ The concentration of CO3. In the single interfering ion performance test... 2- Cl - C2O4 2- SO4 2- NO3 - All were 1 g / L.

[0064] The MoO prepared in Example 1 was observed using transmission electron microscopy. x and U-MoO x Morphological characteristics. For example... Figure 1 and Figure 2 As shown, when a single uranium atom is introduced, U-MoO x MoO remains unchanged x The nanosheet-like morphology of the ultrathin nanosheets indicates that uranium single-atom doping significantly affects U-MoO₂. x The morphology is not affected. For example... Figure 3 As shown, U-MoO x It exhibits three elements, including Mo, O, and U, and these three elements are dispersed throughout the nanosheet. Furthermore, U-MoO... x The uranium content in the nanosheets is relatively low, and the uranium is uniformly dispersed on the nanosheets without spatial separation.

[0065] To investigate the phase composition of the two materials, XRD analysis was performed on the prepared samples. Figure 4 XRD patterns show that MoO x and U-MoO x All showed similarities to MoO 2.69 (JCPDS#70-0615) Similar characteristic diffraction peaks indicate that uranium doping significantly affects MoO₂. x The phase composition was unaffected. Figure 5 The O1s XPS spectra showed two distinct peaks at 529.9 eV and 531.8 eV, corresponding to lattice oxygen atoms near O vacancies and oxygen species adsorbed at oxygen vacancies, respectively, confirming the presence of oxygen vacancy defects in both materials. Meanwhile, in U-MoO...x An additional peak appeared at 535 eV in the O 1s XPS spectrum, which is likely due to uranium oxide. Further verification of the MoOx nanosheets and U-MoO... x Oxygen vacancies in the nanosheets were measured using electron spin resonance (ESR). Figure 6 As shown, MoOx nanosheets and U-MoO x The nanosheets all exhibited significant ESR signals and similar vacancy defect concentrations, indicating that the addition of isolated uranyl did not affect the original MoO₂. x Vacancy concentration in nanosheets.

[0066] Because of the introduction of isolated uranyl, the effect on MoO x The uranium extraction performance of nanosheets and U-MoOx nanosheets in fluorine-containing uranium solutions was tested. The extraction performance was assessed at 100 ppm U(VI) and 3000 ppm F. - MoO2 was tested under coexistence conditions. x Nanosheets and U-MoO x The uranium extraction efficiency of nanosheets as working electrodes varies over time. For example... Figure 7 As shown, after 7 hours of electrochemical extraction, the calculated extraction efficiencies of the two electrode materials were 95.26% and 72.25%, respectively. It can be seen that F... - The strong coordination with uranyl significantly prolongs the uranium extraction time, but due to the presence of isolated uranyl, U-MoO x The extraction efficiency is much greater than that of MoO x .

[0067] Because F- significantly interferes with the reduction and extraction of uranyl, the reduction and extraction of uranyl by the two materials at a low uranium concentration of 50 ppm were compared while keeping the F- concentration constant. Figure 8 As shown. At lower uranium concentrations, MoO x and U-MoO x The uranium extraction efficiencies were 83.65% and 93.9%, respectively. In the presence of isolated uranyl, U-MoO₂ could be observed. x The adsorption kinetics for uranium are higher than those for MoO. x , in MoO x When adsorption equilibrium is reached, U-MoO x It can continue to reduce deposited uranyl. Therefore, through performance comparison, U-MoO x It is the electrode material with the best uranium extraction performance. Furthermore, to demonstrate that the electrochemical process is primarily characterized by electrochemical adsorption rather than physicochemical adsorption, the adsorption capacities of uranium by electroadsorption and physiadsorption were compared, such as... Figure 9 As shown, U-MoO xElectro-adsorption capacity is much greater than that of physicochemical adsorption, therefore it can be concluded that the electrochemical uranium extraction process is mainly based on the electrochemical adsorption of uranium.

[0068] like Figure 10 and Figure 11 As shown, U-MoO2 extracted at 100 ppm for 7 hours... x Electrodesorption was performed on the electrode sheet to evaluate its ability to desorb uranium. The desorption voltage was set to +1.5V, the electrolyte was 80mL of 0.1mol K₂CO₃, and the desorption time was 2h. At +1.5V, the current was 10–15mA. After two hours of positive voltage desorption, the desorption efficiency was calculated to be 89.09%. Therefore, U-MoO₂… x Nanosheets also have excellent uranium desorption capabilities.

[0069] like Figure 12 As shown, further extraction-desorption experiments were conducted to verify the U-MoO2 content. x Cyclic stability of nanosheets. After 5 cycles, U-MoO x The extraction efficiency of uranium from the nanosheets was over 90%, indicating that U-MoO x Nanosheets exhibit good cycling performance. At lower uranium concentrations, U-MoO₂... x Nanosheets still exhibit excellent uranium extraction performance. To further investigate U-MoO₂... x The electrochemical uranium extraction performance of U-MoO under different fluorine-uranium ratios was tested. x The uranium extraction efficiency was measured. The uranium concentration was maintained at 100 ppm, and the fluoride ion concentrations were 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, and 30 g / L, respectively. Figure 13 As shown, increasing the fluorine-to-uranium ratio did not significantly reduce uranium extraction efficiency. At a fluorine-to-uranium ratio of 1:300, U-MoO x The uranium extraction efficiency was as high as 92.8%. These results indicate that U-MoO x As an electrode material for electrochemical uranium extraction, it has excellent uranium extraction capabilities.

[0070] However, in actual uranium extraction from fluoride- and uranium-containing wastewater, the acidity / alkalinity of the solution and the influence of numerous anions must also be considered. Therefore, Figure 14 and Figure 15 Performance test results are shown under 100 ppm uranium conditions, different pH gradients, and single ion interference. It can be seen that U-MoO x It is applicable across a wide pH range, achieving uranium extraction efficiencies exceeding 90%. Under the coexistence of a single anion, CO3... 2- Cl - C2O4 2- SO4 2-The effect on uranium reduction and extraction is almost negligible. This is particularly true in CO3. 2- In its presence, the extraction efficiency of uranium reaches as high as 98.79%. And in NO3... - In existence, U-MoO x The reduced efficiency of uranium extraction is due to some of the electrical energy being used for NO3. - The reduction. To calculate its maximum adsorption capacity, at 500 ppm uranium and 30 g / LF... - Performance tests were conducted under conditions of coexistence with numerous interfering ions. Optical photographs were taken before and after uranium extraction, such as... Figure 16 As shown, after 7 hours of extraction, a large amount of yellow uranium crystals appeared on the electrode plate, with a maximum uranium adsorption capacity of 2382 mg / g. In conclusion, U-MoO₂ is a suitable method for treating high-fluoride uranium-containing wastewater. x It is feasible to use this as an electrode material in conjunction with an electrochemical method for uranium extraction.

[0071] To explore the mechanism of isolated uranyl-enhanced electrochemical uranium extraction, MoO2 was tested in a 100 ppm uranium solution containing 3 g / LF- using a three-electrode system. x and U-MoO x The linear voltammetric scan curve (LSV). For example... Figure 17 As shown, peak values ​​appeared at -0.38V and -0.59V, corresponding to U-MoO, respectively. x and MoO x The reduction potential of U(VI) to U(VI) is given. This indicates that the introduction of isolated uranyl significantly reduces the reduction potential of U-MoO. x The reduction potential of U(VI) greatly improves the efficiency of electrochemical uranium extraction.

[0072] To further verify isolated uranyl-supported MoO x The mechanism of nanosheet performance enhancement, for U-MoO after reaction x and MoO x The XPS O 1s was analyzed. For example... Figure 18 As shown, after 7 hours of electrochemical reaction, U-MoO x The oxygen vacancy O1s spectrum is significantly larger than that of MoO. x This indicates that U-MoO2 after electrochemical uranium extraction x The U-MoO₂ material has more oxygen vacancy defects. Since both materials initially have roughly equivalent oxygen vacancy concentrations, this indicates that U-MoO₂ has more oxygen vacancy defects. x Vacancies are generated during the electrochemical reaction, such as Figure 19 As shown, the signal of oxygen vacancies in the two materials was further investigated using ESR. After electrochemical reduction of uranium extraction, U-MoO x Showing more than MoO xA stronger ESR signal indicates U-MoO x During the electrochemical reaction, oxygen vacancies are generated while uranyl fills the vacancies, thus achieving continuous confined reduction of uranyl at the vacancies.

[0073] like Figure 20 , Figure 21 and Figure 22 As shown, for U-MoO x with MoO x The performance enhancement mechanism of introducing metallic cobalt was verified by TPR, KIE, and material reduction potential tests. The temperature-programmed experiment was conducted using a PCA-1200 semi-automatic chemical analyzer. 50 mg U-MoO₂ was taken... x Nanosheets and MoO x Nanosheet samples were loaded into a high-temperature resistant U-shaped manifold quartz reactor. The temperature was programmed to 300°C, and the reactor was purged with helium at a rate of 40 mL / min for 30 min. After the helium cooled to room temperature, baseline zeroing was performed. Once the baseline was zeroed, a 5% Ar / H₂ mixture was switched, and the temperature was programmed to 1100°C at a rate of 5°C / min. Figure 20 The TPR (temperature programmed reduction) curve shown indicates that MoO x Two reduction peaks appeared at 749℃ and 1015℃, while U-MoO x Reduction peaks appeared at 707℃ and 972℃. Clearly, U-MoO... x The reduction temperature compared to MoO x The decrease was observed. Meanwhile, the LSV curve tested in the presence of only 0.5 M sodium sulfate showed that U-MoO... x with MoO x Peaks appeared at -0.398V and -0.493V respectively, as shown below. Figure 21 As shown, in contrast, U-MoO x The reduction potential is lower than that of MoO x The reduction potential. These all indicate that the introduction of isolated uranyl makes U-MoO x It is more easily reduced. This is because the hydrogen spillover effect leads to U-MoO₂... x To form a hydrogen-rich surface, and to further confirm the hydrogen spillover effect, isotope kinetic effects (KIE) tests were performed in 8 ppm uranium, such as... Figure 22 As shown, U-MoO x The reaction rate constants for heavy water and light water are 0.0049 min. -1 and 0.0107min -1 They are labeled K respectively. D and K H K D and K HThe calculated ratio was 2.184, which indicates that U-MoO x The adsorbed hydrogen species participate in the reduction reaction of uranyl. Combined with the above characterization, this demonstrates that U-MoO x In electrochemical uranium extraction, a hydrogen spillover effect exists, where an active metal adsorbs hydrogen species from the solution and activates them into protons, which are then transferred to MoO. x Above, making MoO x The rapid reduction of metal elements in the uranyl group continuously generates vacancies, which in turn promotes the rapid confined reduction of uranyl and its deposition on U-MoO. x Nanosheet surface.

[0074] To determine the crystal structure and existing forms of uranium, U-MoO2 was collected after electrochemical extraction. x Nanosheets were characterized. For example... Figure 23 As shown, after the reaction, U-MoO x The TME images of the nanosheets indicate that no structural changes occurred, and that U-MoO2 remained unchanged after the reaction. x The elemental mapping of the nanosheets revealed that uranium (U) was distributed throughout the entire nanosheet, confirming the extraction of uranium from fluorine- and uranium-containing wastewater. XRD and XPS characterization techniques were used to determine the species and valence state of the uranium. Figure 24 and Figure 25 As shown in the U 4f high-resolution spectrum, the extracted uranium species simultaneously contain U(VI) and U(IV). Based on the integrated area, 67.25% of U(VI) is reduced to U(IV). The XRD pattern records uranium species such as K₂UO₄ (JCPDS#72-2228) and UO₂ (JCPDS#73-1715), corresponding to the hexavalent and tetravalent valence states of uranium in XPS. The presence of K₂MoO₄ (JCPDS#72-0735) crystals is due to the presence of MoO₂. x The presence of molybdenum in a low valence state allows it to reduce hexavalent uranyl, thus forming this crystal.

[0075] The above results demonstrate that in fluorine-containing uranium-containing systems, the complexation of fluoride ions with uranyl significantly increases the difficulty of electrochemical uranium extraction. This invention successfully introduces isolated uranyl groups into MoO₂. x Nanosheets enabled highly efficient electrochemical reduction and deposition of uranium in fluoride- and uranium-containing wastewater. (3 g / LF) - Under conditions of coexistence with 100 ppm uranium, U-MoO x The nanosheet uranium extraction efficiency reached 95.26%, and 7.13 mg of uranium was desorbed within two hours after applying a positive voltage of 1.5V. In solution systems with different fluorine-to-uranium ratios, U-MoO₂… x The extraction efficiency of uranyl was maintained at 90%. U-MoO xThe nanosheets exhibited good cycling stability in multiple U(VI) capture tests and demonstrated excellent resistance to ion interference. In uranium enrichment experiments, yellow uranium oxide was extracted with an adsorption capacity as high as 2382 mg / g. Mechanistic studies showed that the introduction of isolated uranyl groups and MoO2... x An interfacial bond structure is formed between them, which lowers the reduction potential of uranyl. During electrolysis, isolated uranyl-MoO x This creates an interfacial hydrogen spillover effect, enabling the regeneration of uranium active sites and ensuring the continuous reduction and deposition of uranyl.

[0076] U-MoO prepared using Example 1 x Nanosheets for uranium extraction from seawater, such as Figure 26 , Figure 27 , Figure 28 and Figure 29 As shown, the structure of the electrochemical uranium extraction system includes:

[0077] A floating plate 1 has a PVC fixed mesh pipe 2 on its upper surface, and a solar panel (not shown) is laid on the PVC fixed mesh pipe 2.

[0078] Electrode pool 3 is located below the float plate 1 and is connected to the PVC fixed mesh pipe 2 by steel wire rope 4. Water inlets 5 are respectively provided at the upper and lower ends of electrode pool 3. An aluminum plate 6 is installed in the water inlet 5 and has multiple small holes. Multiple exhaust ports 7 are provided at the top of electrode pool 3 and are connected to the atmosphere through a flexible hose (not shown).

[0079] The electrode cell 3 is externally provided with a counterweight mechanism, which includes:

[0080] The base plate 8 is disposed at the bottom of the electrode cell 3;

[0081] The top plate 9 is located at the upper end of the electrode pool 3. A connecting column 10 connects the bottom plate 8 and the top plate 9. The steel wire rope 4 is detachably connected to the top plate 9.

[0082] The electrode cell 3 is provided with a platinum electrode 11, a first cathode plate 12 and a second cathode plate 13, wherein the first cathode plate 12 and the second cathode plate 13 are connected by a tin bronze plate 14.

[0083] The solar panel is connected to a controller, which is connected to a battery for energy storage and a pure sine wave inverter. The pure sine wave inverter is connected to a high-frequency power supply. The platinum electrode 11, the first cathode plate 12, and the second cathode plate 13 are connected to the high-frequency power supply via cables.

[0084] Carbon paper is disposed on the first cathode plate 12 and the second cathode plate 13, and ink is coated on the carbon paper. The method for preparing the ink includes: U-MoO x Nanomaterial samples, carbon black, and a 0.5 wt% Nafion solution were dissolved in alcohol and ultrasonically treated for 0.5 h to obtain a uniform ink containing U-MoO. x The mass-to-volume ratio of nanomaterial sample, carbon black, Nafion solution and alcohol was 1–10 mg: 1–10 mg: 10–70 μL: 1–8 mL.

[0085] In operation, the electrochemical uranium extraction device of this invention uses a float plate 1 to suspend the electrode cell 3 in seawater or other uranium-containing wastewater. Solar panels installed on a PVC fixed mesh pipe 2 provide power to the entire device. The solar panels store electrical energy in batteries via a controller, or directly power a sine wave inverter via the controller. The inverter outputs 220V AC power at 50Hz. High-frequency power is supplied to the output of the inverter via cables, supplying high-frequency power to the platinum electrode 11, the first cathode plate 12, and the second cathode plate 13 of the electrode cell 3. Seawater or other uranium-containing wastewater enters the electrode cell 3 through two inlets 5. The first and second cathode plates 12 and 13 are coated with U-MoO. x When the ink in the nanomaterial sample is electrolyzed, platinum electrode 11 serves as the anode, and the first cathode plate 12 and the second cathode plate 13 serve as the cathodes. U(VI) in seawater or other uranium-containing wastewater is reduced and adsorbed onto the surfaces of the first cathode plate 12 and the second cathode plate 13, thus realizing U-MoO x The purpose of using nanomaterials for uranium extraction is as follows: The first cathode plate 12 and the second cathode plate, connected by a tin bronze plate 14, together form the cathode. This arrangement increases the surface area of ​​the cathode, thereby increasing the contact area between the cathode and the uranium-containing wastewater (seawater), and thus increasing the mass of uranium reduced and adsorbed by the cathode. To prevent small marine organisms such as shellfish and fish from entering the electrode pool 3, the inlet 5 of the electrode pool 3 is equipped with a perforated aluminum plate 6, which filters the seawater. To prevent the large amount of hydrogen gas generated during electrolysis from affecting the experimental results, an exhaust port 7 is installed at the top of the electrode pool 3. The exhaust port 7 is connected to the atmosphere through a flexible hose, releasing excess gas into the environment. The counterweight mechanism is made of 316L stainless steel, ensuring that the electrode pool 3 can be completely submerged in seawater while also resisting a certain degree of overturning effect of waves on the entire electrochemical uranium extraction device.

[0086] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0087] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction, characterized in that, Includes the following steps: Step 1: Synthesis of MoO x Nanosheets, x < 3; Step 2: Add MoO x Nanosheets and UO2(NO3)2·6H2O were dispersed in deionized water, and photocatalysis was performed for a certain period of time to ensure the fixation and reduction of uranyl. After the reaction was completed, the precipitate was concentrated by centrifugation and dried overnight at a certain temperature to obtain U-MoO2. x Nanosheets; MoO x The mass-to-volume ratio of nanosheets, UO2(NO3)2·6H2O, and deionized water was 50~200 mg : 1~15 mg : 5~30 mL; The photocatalytic time was 1–12 h, and the overnight drying temperature was 40–80 °C. The U-MoO x The application of nanosheets in the extraction of uranium from uranium-containing wastewater includes: using an electrochemical workstation with Ag / AgCl and Pt wire as the reference and counter electrodes, respectively, and preparing a 3.5 M potassium chloride solution as the electrolyte; Will U-MoO x Nanomaterial samples, carbon black, and a 0.5 wt% Nafion solution were dissolved in alcohol and ultrasonically treated for 0.5 h to obtain a uniform ink containing U-MoO. x The mass-to-volume ratio of nanomaterial sample, carbon black, Nafion solution, and alcohol was 1–10 mg : 1–10 mg : 10–70 μL : 1–8 mL; then, the ink was brushed onto 1 × 2 cm carbon paper as the working electrode, and the U-MoO was subjected to potentiostatic method. x The reducing power of nanomaterials on U(VI) was determined.

2. The method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction as described in claim 1, characterized in that, In step one, MoO is synthesized. x The methods for nanosheets include: Molybdenum metal powder was mixed with 1-butanol, and then hydrogen peroxide was added. The mixture was stirred for a certain period of time to form a pure yellow solution. The final solution was transferred to an autoclave, heated and kept at that temperature for a certain period of time, and the sediment was concentrated by centrifugation. The sediment was washed several times with anhydrous ethanol and deionized water, and then dried overnight to obtain MoO2. x Nanosheets.

3. The method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction as described in claim 2, characterized in that, The molybdenum metal powder, 1-butanol, and hydrogen peroxide are used in a ratio of 1-6 mmol : 12-80 mL : 1-10 mL, and the mass fraction of hydrogen peroxide is 10-40 wt%.

4. The method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction as described in claim 2, characterized in that, The stirring time after adding hydrogen peroxide is 10~60 min, the heating temperature of the autoclave is 120~180℃, the holding time is 6~24 h, and the overnight drying temperature is 40~80℃.

5. An electrochemical uranium extraction system, comprising U-MoO prepared using the method for preparing molybdenum oxide-based nanosheets for electrochemical uranium extraction according to any one of claims 1-4. x Nanosheets, characterized in that, The structure of the electrochemical uranium extraction system includes: A floating plate with a PVC fixed mesh tube on its upper surface, on which a solar panel is laid; An electrode pool is located below the float plate and is connected to the PVC fixed mesh pipe by a steel wire rope. The upper and lower ends of the electrode pool are respectively provided with water inlets, and an aluminum plate is installed in the water inlet. The aluminum plate is provided with multiple small holes. The top of the electrode pool is provided with multiple exhaust ports, and the exhaust ports are connected to the atmosphere through flexible hoses. The electrode cell is externally equipped with a counterweight mechanism, which includes: A base plate is disposed at the bottom of the electrode cell; A top plate is disposed at the upper end of the electrode pool, a connecting column is connected between the bottom plate and the top plate, and the steel wire rope is detachably connected to the top plate; The electrode cell is internally provided with a platinum electrode, a first cathode plate and a second cathode plate, wherein the first cathode plate and the second cathode plate are connected by a tin bronze plate. The solar panel is connected to a controller, which is connected to a battery for energy storage and a pure sine wave inverter. The pure sine wave inverter is connected to a high-frequency power supply. The platinum electrode, the first cathode plate, and the second cathode plate are connected to the high-frequency power supply via cables. Carbon paper is disposed on the first cathode plate and the second cathode plate, and the carbon paper is coated with ink. The method for preparing the ink includes: U-MoO x Nanosheet samples, carbon black, and a 0.5 wt% Nafion solution were dissolved in alcohol and ultrasonically treated for 0.5 h to obtain a uniform ink containing U-MoO. x The mass-to-volume ratio of nanosheet sample, carbon black, Nafion solution and alcohol was 1~10 mg : 1~10 mg : 10~70 μL : 1~8 mL.

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