Preparation of flaky bimetal oxide for electrochemical uranium extraction and application of flaky bimetal oxide in nuclear wastewater treatment

Abstract

The invention discloses preparation of a flaky bimetal oxide for electrochemical uranium extraction and application of the flaky bimetal oxide in nuclear wastewater treatment, and belongs to the technical field of nuclear wastewater treatment, metal oxides and nanomaterials, and the preparation method comprises the following steps: adding single-layer graphene oxide into high-purity water, stirring and dispersing, sequentially adding ammonium formate and formic acid, and carrying out ultrasonic dispersion to obtain a solution A; the preparation method comprises the following steps: adding Bi (NO3) 3.5 H2O and Ce (NO3) 3.6 H2O into high-purity water, and ultrasonically dispersing uniformly to obtain a solution B; putting the solution A into an oil bath pan for preheating and heat preservation, dropwise adding the solution B, carrying out heat preservation and centrifugal washing, then collecting precipitates, and putting the precipitates into a freeze-drying machine for freeze-drying to obtain a flaky bimetallic oxide precursor; the precursor of the flaky bimetallic oxide is evenly laid on a porcelain boat, the porcelain boat is put into a high-temperature furnace to be subjected to pyrolysis oxidation, and the flaky bimetallic oxide Bi2O3-CeO2 is obtained. The flaky bimetal oxide Bi2O3-CeO2 prepared by the method disclosed by the invention has relatively high uranium extraction efficiency and analysis efficiency, can be used for uranium extraction and analysis for multiple times, and can meet the requirement of long-term recycling.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear wastewater treatment, metal oxides and nanomaterials, and more specifically, to the preparation of a sheet-like bimetallic oxide for electrochemical uranium extraction and its application in nuclear wastewater treatment. Background Art

[0002] With the development of the nuclear industry, a large amount of uranium-containing wastewater is produced during the nuclear power fuel cycle, which poses a radioactive risk to the environment and leads to the loss of precious uranium resources. Traditional methods such as adsorption and ion exchange are not effective in treating high-concentration uranium (U>100mg / L) and fluoride ions (F - Up to 30g / L) coexisting wastewater is inefficient because F - It will interfere with the complex form of uranium and affect the extraction effect. The electrochemical reduction method can convert U(VI) into an insoluble crystalline product, thereby improving the extraction efficiency of uranium, which brings new ideas for improving the extraction efficiency of uranium in complex environments. Carbonaceous electrode materials modified with surface functional groups can effectively extract uranium from nuclear wastewater through electrochemistry, indicating that electrochemical uranium extraction can be carried out at high concentrations of F - The traditional design of electrochemical uranium extraction electrode materials is to introduce functional groups that bind to U(VI). However, due to the presence of F in uranium production wastewater, - The molar ratio of / U(VI) reaches 10 3 , the type of uranium belongs to UO 2 F x And with a lot of F - Conventional electrode materials are inefficient and unstable in the actual system of high-fluorine uranium-containing wastewater. Therefore, it is necessary to rationally design an electrode material that can improve the uranium recovery efficiency for electrochemical uranium extraction from fluorine-containing nuclear fuel wastewater. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages according to the present invention, a method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction is provided, comprising the following steps:

[0005] Step 1: adding a monolayer graphene oxide to high-purity water, and then stirring and dispersing until the monolayer graphene oxide is completely dispersed, adding ammonium formate and formic acid in sequence, and then ultrasonically dispersing to obtain a solution A with the monolayer graphene oxide as a carrier;

[0006] Step 2: Bi(NO 3 ) 3 ·5H 2 O and Ce(NO 3 )3 6H 2 O was added into high-purity water and then dispersed evenly by ultrasonic to obtain Bi 3+ and Ce 3+ is the metal-loaded solution B;

[0007] Step 3, after preheating solution A in an oil bath, slowly drip solution B, keep warm for a period of time, collect the precipitate after centrifugal washing, and freeze-dry in a freeze dryer to obtain a precursor of a flaky bismuth-cerium bimetallic oxide;

[0008] Step 4: The precursor of the flaky bismuth-cerium bimetallic oxide is evenly spread on a porcelain boat, and then placed in a high-temperature furnace for pyrolysis and oxidation for a period of time to obtain a flaky bimetallic oxide Bi 2 O 3 -CeO 2 .

[0009] Preferably, in step 1, in solution A, the mass volume ratio of single-layer graphene oxide, high-purity water, formic acid and ammonium formate is 5-20 mg: 50-200 ml: 1-5 g: 90-360 μL.

[0010] Preferably, in step 1, the stirring and dispersing time is 24 to 48 hours, and the ultrasonic dispersing time is 1 to 2 hours.

[0011] Preferably, in step 2, in solution B, Bi(NO 3 ) 3 ·5H 2 O、Ce(NO 3 ) 3 6H 2 O. The mass-to-volume ratio of high-purity water is 0.24-1g:0.6-2.4g:20-100mL.

[0012] Preferably, in step 3, the preheating temperature of the oil bath is 75-85° C., the dropping speed of solution B is 5-10 ml / min, the insulation time is 1-2 h, and the freeze-drying time is 24-48 h.

[0013] Preferably, in step 4, the heating rate of the pyrolysis oxidation is 1-5°C / min, the pyrolysis oxidation temperature is 650-750°C, and the holding time is 2-6h.

[0014] An application of a flaky bimetallic oxide in nuclear wastewater treatment, wherein the flaky bimetallic oxide is applied as a catalyst for electrochemical uranium extraction in nuclear wastewater treatment, wherein the flaky bimetallic oxide is loaded on a carbon felt electrode as a working electrode, and uranium is electrochemically extracted from uranium-containing nuclear wastewater, and the specific method includes:

[0015] S1. Dispersing the flaky bimetallic oxide as a catalyst in a mixed solution of anhydrous ethanol and Nafion solution and ultrasonically treating it to obtain a homogeneous catalyst solution, ultrasonically treating the carbon felt with a mixture of ethanol and deionized water, and then immersing the carbon felt in the homogeneous catalyst solution for 6 to 12 hours, taking it out and drying it to achieve the loading of the flaky bimetallic oxide on the carbon felt, and in a conventional three-electrode system of an electrochemical workstation, using a fluorine-containing uranium-containing solution as a nuclear waste water simulation solution, using a platinum wire and Ag / AgCl as a counter electrode and a reference electrode, respectively, and using a carbon felt electrode as a working electrode, an electrochemical uranium extraction experiment is performed;

[0016] S2. Place the working electrode after electrochemical uranium extraction in a sodium carbonate electrolyte, apply a constant positive potential, desorb the working electrode, and place the desorbed working electrode again in a simulated nuclear waste water solution to conduct a cyclic uranium extraction experiment; then conduct electrochemical uranium extraction experiments at different pH values ​​and under different interfering ions according to the method of S1.

[0017] Preferably, in S1, the mass volume ratio of catalyst, anhydrous ethanol and Nafion solution is 5-20 mg: 2-8 ml: 10-30 uL, the ultrasonic treatment time is 10-20 min, and the loading amount of catalyst is fixed at 3-5 mg / cm 2 .

[0018] Preferably, in said S2, the constant positive potential is 1-2V.

[0019] Preferably, in said S1, UO in the simulated nuclear wastewater solution 2 2+ Concentration ≥ 100 mg / L, F - Concentration ≥30g / L.

[0020] In order to further improve the extraction capacity of uranium from fluorine-uranium wastewater by flake bimetallic oxides, the scheme of step 1 is replaced by:

[0021] S11, dispersing the hydrated titanium dioxide powder in anhydrous ethanol, stirring and mixing evenly, adding 3-aminopropyltriethoxysilane, dispersing by ultrasonic at 50-80kHz for 20-40min, refluxing at 80-90°C for 6-12h, cooling to room temperature, centrifuging, washing and drying to obtain the aminated hydrated titanium dioxide powder; wherein the amount ratio of the hydrated titanium dioxide powder, 3-aminopropyltriethoxysilane and anhydrous ethanol is 1-5g:0.5-1mL:50-150mL;

[0022] S12, adding a monolayer graphene oxide to high-purity water, and then stirring and dispersing until the monolayer graphene oxide is completely dispersed to obtain a dispersion; adding aminated hydrated titanium dioxide powder and surfactant F127 to the dispersion, stirring and heating to 60-80° C., keeping warm for 1-3 hours, and cooling to room temperature to obtain a mixed dispersion; wherein the amount ratio of the monolayer graphene oxide, the aminated hydrated titanium dioxide powder and the surfactant F127 is 5-20 mg: 1-10 mg: 0.01-0.5 mg;

[0023] S13, adding ammonium formate and formic acid to the mixed dispersion in sequence, and then dispersing by ultrasonication to obtain a solution A with a single-layer graphene oxide as a carrier.

[0024] The present invention has at least the following beneficial effects:

[0025] (1) The flaky bismuth-cerium bimetallic oxide prepared by the present invention 2 O 3 -CeO 2 It has a high uranium extraction efficiency. - The extraction capacity in uranium wastewater with a concentration of up to 30 g / L reached 1505.8 mg / g;

[0026] (2) The flaky bismuth-cerium bimetallic oxide Bi of the present invention 2 O 3 -CeO 2 Has high parsing efficiency;

[0027] (3) The flake bismuth-cerium bimetallic oxide of the present invention 2 O 3 -CeO 2 It has a high uranium extraction efficiency under different pH conditions and can adapt to the acidic and alkaline wastewater produced in different nuclear fuel production stages;

[0028] (4) The flake bismuth-cerium bimetallic oxide of the present invention 2 O 3 -CeO 2 The extraction efficiency is still high in uranium wastewater with common interfering ions;

[0029] (5) The flake bismuth-cerium bimetallic oxide of the present invention 2 O 3 -CeO 2 It can be used for uranium extraction and analysis multiple times and can meet the needs of long-term recycling.

[0030] (6) When the present invention uses a monolayer graphene oxide to prepare a solution A with a monolayer graphene oxide as a carrier, an aminated hydrated titanium dioxide powder is added thereto, and the monolayer graphene oxide and the aminated hydrated titanium dioxide powder are dispersed by using the tri-prepolymer surfactant F127 to prevent particle agglomeration; at the same time, F127 guides the arrangement and bonding between the monolayer graphene oxide and the aminated hydrated titanium dioxide powder, improves the tightness of the bonding between the two, promotes the interlayer intercalation mesoporous structure, and increases the specific surface area of ​​the graphene oxide-aminated hydrated titanium dioxide powder composite powder; the results show that the flaky bismuth-cerium bimetallic oxide Bi prepared by adding the aminated hydrated titanium dioxide powder 2 O 3 -CeO 2 It has stronger uranium extraction capability.

[0031] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The flaky bismuth-cerium bimetallic oxide Bi prepared in Example 1 of the present invention 2 O 3 -CeO 2 SEM images of

[0033] Figure 2 The flaky bismuth-cerium bimetallic oxide Bi prepared in Example 1 of the present invention 2 O 3 -CeO 2 High-resolution transmission electron microscopy images of

[0034] Figure 3 The flaky bismuth-cerium bimetallic oxide Bi prepared in Example 1 of the present invention 2 O 3 -CeO 2 EDS element mapping images;

[0035] Figure 4 The XRD patterns of Example 1, Comparative Example 1 and Comparative Example 2 of the present invention are shown in FIG.

[0036] Figure 5 The flaky bismuth-cerium bimetallic oxide Bi prepared in Example 1 of the present invention 2 O 3 -CeO 2 , Comparative Example 1 prepared sheet metal oxide Bi 2 O 3 , Comparative Example 2 prepared flake metal oxide CeO 2 Graph of uranium extraction efficiency within 300 min;

[0037] Figure 6 The bismuth-cerium bimetallic oxide Bi loaded in the application example 1 of the present invention 2 O 3 -CeO 2 The deposition state of uranium on the carbon felt electrode at different times;

[0038] Figure 7 The bismuth-cerium bimetallic oxide Bi loaded in the application example 1 of the present invention 2 O 3 -CeO 2 Graph of desorption efficiency of uranium in 0.1M sodium carbonate desorption solution;

[0039] Figure 8 The bismuth-cerium bimetallic oxide Bi loaded in the application example 1 of the present invention 2 O 3 -CeO 2 Plots of uranium extraction efficiency and extracted mass with initial concentration;

[0040] Fig. 9 The flaky bismuth-cerium bimetallic oxide Bi under different pH conditions in Example 1 of the present invention 2 O 3 -CeO 2 Graph of uranium extraction efficiency;

[0041] Fig.10 For Application Example 1 of the present invention, - After adding different interfering ions in the presence of Bi-Ce bimetallic oxide 2 O 3 -CeO 2 Graph of uranium extraction efficiency;

[0042] Fig.11 Example 1 of the present invention is a sheet-like bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Graph of uranium extraction efficiency for recycling use;

[0043] Fig.12 This is a diagram of uranium extraction efficiency in real nuclear waste water in Application Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0045] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0046] Example 1

[0047] A flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The preparation method comprises the following steps:

[0048] Step 1: Add 5 mg of monolayer graphene oxide to 50 mL of high-purity water, and then stir for 24 h to disperse until the monolayer graphene oxide is completely dispersed, add 1.26 g of ammonium formate and 90 uL of formic acid in sequence, and then ultrasonically disperse for 1 h to obtain a solution A with the monolayer graphene oxide as the carrier;

[0049] Step 2: 0.24 g Bi(NO 3 ) 3 ·5H 2 O and 0.6g Ce(NO 3 ) 3 6H 2 O was added into 20 mL of high-purity water and then dispersed evenly by ultrasonication to obtain Bi 3+ and Ce 3+ is the metal-loaded solution B;

[0050] Step 3: Preheat solution A in a 75°C oil bath, then slowly drip the loading solution B at a rate of 5 ml / min, keep warm for 1 hour, then collect the precipitate after centrifugal washing, and freeze dry it in a freeze dryer for 24 hours to obtain a flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Precursor of

[0051] Step 4: Flake Bismuth-Cerium Bimetallic Oxide 2 O 3 -CeO 2 The precursor was evenly spread on a porcelain boat, placed in a high-temperature furnace, and heated to 650°C at a rate of 1°C / min for 2h to obtain a flaky bimetallic oxide Bi 2 O 3 -CeO 2 .

[0052] Example 2

[0053] A flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The preparation method comprises the following steps:

[0054] Step 1: Add 10 mg of monolayer graphene oxide into 100 mL of high-purity water, and then stir for 48 h to disperse until the monolayer graphene oxide is completely dispersed, add 2.52 g of ammonium formate and 180 uL of formic acid in sequence, and then ultrasonically disperse for 2 h to obtain a solution A with the monolayer graphene oxide as the carrier;

[0055] Step 2: 0.48 g Bi(NO 3 ) 3 ·5H 2 O and 1.2g Ce(NO 3 ) 3 6H 2 O was added into 40 mL of high-purity water and then ultrasonically dispersed to obtain Bi 3+ and Ce 3+ is the metal-loaded solution B;

[0056] Step 3, preheating solution A in an oil bath at 85°C, then slowly dripping solution B at a rate of 10 ml / min, keeping warm for 2 hours, then collecting the precipitate after centrifugal washing, and freeze-drying it in a freeze dryer for 48 hours to obtain a precursor of a flaky bimetallic oxide;

[0057] Step 4: The precursor of the flaky bimetallic oxide is evenly spread on a porcelain boat, placed in a high-temperature furnace, and pyrolyzed and oxidized at 750°C at a heating rate of 5°C / min for 6 hours to obtain a flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 .

[0058] Example 3

[0059] A flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The preparation method is different from Example 1 in that the scheme of step 1 is replaced by:

[0060] S11, dispersing 1 g of hydrated titanium dioxide powder in 50 mL of anhydrous ethanol, stirring and mixing evenly, adding 0.5 mL of 3-aminopropyltriethoxysilane, dispersing by ultrasonic at 60 kHz for 40 min, reflux at 80° C. for 6 h, cooling to room temperature, centrifuging, washing, and drying to obtain amino-hydrated titanium dioxide powder;

[0061] S12, adding 5 mg of monolayer graphene oxide to 50 mL of high-purity water, and then stirring and dispersing for 24 hours until the monolayer graphene oxide is completely dispersed to obtain a dispersion; adding 1 mg of amino-hydrated titanium dioxide powder and 0.1 mg of surfactant F127 to the dispersion, stirring and heating to 80° C., keeping the temperature for 2 hours, and cooling to room temperature to obtain a mixed dispersion;

[0062] S13. Add 1.26 g of ammonium formate and 90 μL of formic acid to the mixed dispersion in sequence, and then disperse it ultrasonically for 1 hour to obtain a solution A with a single-layer graphene oxide as a carrier.

[0063] The methods and process parameters of steps 2 to 4 of this embodiment are the same as those of embodiment 1.

[0064] Example 4

[0065] A flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The preparation method is different from Example 1 in that the scheme of step 1 is replaced by:

[0066] S11, dispersing 2.5 g of hydrated titanium dioxide powder in 50 mL of anhydrous ethanol, stirring and mixing evenly, adding 1 mL of 3-aminopropyltriethoxysilane, dispersing by ultrasonic at 60 kHz for 40 min, reflux at 90 ° C for 6 h, cooling to room temperature, centrifuging, washing, and drying to obtain amino hydrated titanium dioxide powder;

[0067] S12, adding 5 mg of monolayer graphene oxide to 50 mL of high-purity water, and then stirring and dispersing for 24 hours until the monolayer graphene oxide is completely dispersed to obtain a dispersion; adding 2 mg of amino-hydrated titanium dioxide powder and 0.3 mg of surfactant F127 to the dispersion, stirring and heating to 80° C., keeping the temperature for 2 hours, and cooling to room temperature to obtain a mixed dispersion;

[0068] S13. Add 1.26 g of ammonium formate and 90 μL of formic acid to the mixed dispersion in sequence, and then disperse it ultrasonically for 1 hour to obtain a solution A with a single-layer graphene oxide as a carrier.

[0069] The methods and process parameters of steps 2 to 4 of this embodiment are the same as those of embodiment 1.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is that in step 2 of this comparative example, only Bi(NO 3 ) 3 ·5H 2 O, without adding Ce(NO 3 ) 3 6H 2 O, and finally obtain the sheet metal oxide Bi 2 O 3 .

[0072] Comparative Example 2

[0073] The difference between this comparative example and Example 1 is that in step 2 of this comparative example, only Ce(NO 3 ) 3 6H 2 O, without adding Bi(NO 3 ) 3 ·5H 2 O, and finally obtain the flake metal oxide CeO 2 .

[0074] Comparative Example 3

[0075] A flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The preparation method of Example 3 is different from that of Example 3 in that the hydrated titanium dioxide powder is not aminated in this comparative example, and step 1 is replaced by:

[0076] S11, adding 5 mg of monolayer graphene oxide to 50 mL of high-purity water, and then stirring and dispersing for 24 hours until the monolayer graphene oxide is completely dispersed to obtain a dispersion; adding 1 mg of hydrated titanium dioxide powder and 0.1 mg of surfactant F127 to the dispersion, stirring and heating to 80° C., keeping the temperature for 2 hours, and cooling to room temperature to obtain a mixed dispersion;

[0077] S12. 1.26 g of ammonium formate and 90 μL of formic acid were added to the mixed dispersion in sequence, and then ultrasonically dispersed for 1 h to obtain a solution A with a single-layer graphene oxide as a carrier.

[0078] The methods and process parameters of steps 2 to 4 of this embodiment are the same as those of embodiment 3.

[0079] Comparative Example 4

[0080] A flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The preparation method of the present comparative example is different from that of Example 1 in that the steps of the present comparative example are as follows:

[0081] Step 1: Add 5 mg of monolayer graphene oxide to 50 mL of high-purity water, and then stir for 24 h to disperse until the monolayer graphene oxide is completely dispersed, add 1.26 g of ammonium formate and 90 uL of formic acid in sequence, and then ultrasonically disperse for 1 h to obtain a solution A with the monolayer graphene oxide as the carrier;

[0082] Step 2: 0.24 g Bi(NO 3 ) 3 ·5H 2 O and 0.6g Ce(NO 3 ) 3 6H2 O was added into 20 mL of high-purity water and then dispersed evenly by ultrasonication to obtain Bi 3+ and Ce 3+ is the metal-loaded solution B;

[0083] Disperse 1 g of hydrated titanium dioxide powder in 50 mL of anhydrous ethanol, stir and mix evenly, add 0.5 mL of 3-aminopropyltriethoxysilane, disperse under 60 kHz ultrasonication for 40 min, reflux at 80 °C for 6 h, cool to room temperature, centrifuge, wash and dry to obtain amino hydrated titanium dioxide powder, add 1 mg of amino hydrated titanium dioxide powder and 0.1 mg of surfactant F127 to solution B;

[0084] Step 3: Preheat solution A in a 75°C oil bath, then slowly drip the loading solution B at a rate of 5 ml / min, keep warm for 1 hour, then collect the precipitate after centrifugal washing, and freeze dry it in a freeze dryer for 24 hours to obtain a flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Precursor of

[0085] Step 4: Flake Bismuth-Cerium Bimetallic Oxide 2 O 3 -CeO 2 The precursor was evenly spread on a porcelain boat, placed in a high-temperature furnace, and heated to 650°C at a rate of 1°C / min for 2h to obtain a flaky bimetallic oxide Bi 2 O 3 -CeO 2 .

[0086] from Figure 1 It can be seen that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 It appears in micron-scale flake form; Figure 2 It can be seen that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The interplanar spacings are 0.31nm and 0.32nm respectively; Figure 3 It can be seen that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 It is composed of Bi, O, and Ce elements uniformly; Figure 4 It can be seen from the XRD pattern that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Show Bi 2 O3 and CeO 2 The characteristic peaks of the composite phase, while the flake metal oxide Bi 2 O 3 and flake metal oxide CeO 2 They showed Bi 2 O 3 and CeO 2 The single-phase characteristic peaks of the bimetallic oxides in Bi 2 O 3 -CeO 2 Co-existence.

[0087] Application Example 1

[0088] The flaky bismuth-cerium bimetallic oxide Bi obtained in Example 1 2 O 3 -CeO 2 The electrochemical performance test in simulated nuclear waste water includes the following steps:

[0089] S1. A 2×3 cm carbon felt was used as a carrier and subjected to ultrasonic treatment with a mixture of ethanol and deionized water. 18 mg of the sheet-like bimetallic oxide Bi prepared in Example 1 was added. 2 O 3 -CeO 2 The carbon felt was dispersed in a mixed solution of 2 ml of anhydrous ethanol and 30 μL of Nafion solution, transferred and ultrasonicated for 20 min to obtain a homogeneous catalyst solution, and then the carbon felt was immersed in the homogeneous catalyst solution for 6 h, taken out and dried to achieve the formation of the bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Loaded on carbon felt, the loading amount is 3mg / cm 2 In a conventional three-electrode system on an electrochemical workstation (CHI660), in 50 ml of high-fluorine uranium solution (U concentration and F concentration were 100 mg / L and 30 g / L, respectively), platinum wire and Ag / AgCl were used as the counter electrode and reference electrode, respectively, and the bismuth-cerium bimetallic oxide Bi was loaded. 2 O 3 -CeO 2 The carbon felt electrode was used as the working electrode to complete the corresponding electrochemical uranium extraction experiment.

[0090] S2, placing the working electrode after uranium extraction in a 0.1M sodium carbonate electrolyte, applying a constant positive potential of 1.5V, desorbing the working electrode, placing the desorbed working electrode again in a simulated solution, performing a cyclic electrochemical uranium extraction experiment, and performing electrochemical uranium extraction experiments at different pH values ​​and different interfering ions;

[0091] S3. Prepare the working electrode according to the method of S1, and use a common electrolytic cell to carry out the actual nuclear waste water electrochemical uranium extraction experiment.

[0092] At the same time, according to the method of Application Example 1, the flaky bismuth-cerium bimetallic oxide Bi prepared in Examples 2 to 4 was 2 O 3 -CeO 2 , Comparative Example 1 prepared sheet metal oxide Bi 2 O 3 , Comparative Example 2 prepared flake metal oxide CeO 2 , Comparative Examples 3-4 prepared flaky bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Conduct electrochemical performance tests in simulated nuclear wastewater.

[0093] from Figure 5 It can be seen that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The uranium extraction efficiency is 95%, respectively Bi 2 O 3 and CeO 2 1.3 and 1.5 times of Figure 6 It can be seen that during the uranium extraction process, the macroscopic crystals of uranium grow on the flake-supported bimetallic oxide Bi 2 O 3 -CeO 2 On carbon felt electrode; Figure 7 It can be seen that after a typical electrochemical desorption process, the crystalline product is released into a dilute sodium carbonate solution. 2 O 3 -CeO 2 The desorption efficiency of uranium is 95.1%; Figure 8 It can be seen that when the initial uranium concentration is within 50-500 mg / L, the bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 It still has a high uranium extraction efficiency (>90%), with a maximum extraction capacity of 1505.8 mg / g (F - The concentration is 30 g / L), while the flake bismuth-cerium bimetallic oxide Bi prepared in Example 3 and Example 4 2 O 3 -CeO 2 Under the same conditions, the maximum uranium extraction capacity was 1765.2 mg / g and 1744.8 mg / g respectively, which was higher than that of the flaky bismuth-cerium bimetallic oxide Bi prepared in Example 1.2 O 3 -CeO 2 The extraction capacity of uranium has been significantly improved. The flaky bismuth-cerium bimetallic oxide Bi prepared in Comparative Examples 3 and 4 2 O 3 -CeO 2 Under the same conditions, the maximum uranium extraction capacities were 1051.5 mg / g and 1248.0 mg / g respectively; Fig. 9 It can be seen that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The uranium extraction efficiency in the pH range of 3 to 10 was >90%, indicating that the bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 Adaptability to uranium extraction in various situations, such as acidic wastewater from nuclear fuel element manufacturing and alkaline wastewater from uranium enrichment; Fig.10 It can be seen that with common interfering ions such as CO 3 2- 、NO 3 - , Cl - 、SO 4 2- , C 2 O 4 2- and NH 4 + The coexistence of flaky metal oxides Bi 2 O 3 and flake metal oxide CeO 2 The uranium extraction efficiency of the bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 The extraction efficiency decreases minimally; Fig.11 It can be seen that the flake bismuth-cerium bimetallic oxide Bi 2 O 3 -CeO 2 It worked well in 10 uranium extraction and desorption cycles, indicating that it can be used in long-term cycles. Fig.12 As shown, the uranium extraction efficiency in real nuclear wastewater can reach up to 92.6%.

[0094] The number of devices and processing scales described here are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be obvious to those skilled in the art.

[0095] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction, characterized in that: The following steps are involved: Step 1: adding a monolayer graphene oxide to high-purity water, and then stirring and dispersing until the monolayer graphene oxide is completely dispersed, adding ammonium formate and formic acid in sequence, and then ultrasonically dispersing to obtain a solution A with the monolayer graphene oxide as a carrier; Step 2: Add Bi(NO3)3·5H2O and Ce(NO3)3·6H2O into high-purity water, and then disperse them evenly with ultrasound to obtain Bi 3+ and Ce 3+ is the metal-loaded solution B; Step 3, after preheating solution A in an oil bath, slowly drip solution B, keep warm for a period of time, collect the precipitate after centrifugal washing, and freeze-dry in a freeze dryer to obtain a precursor of a flaky bismuth-cerium bimetallic oxide; Step 4: The precursor of the flaky bismuth-cerium bimetallic oxide is evenly spread on a porcelain boat, and placed in a high-temperature furnace for pyrolysis and oxidation for a period of time to obtain the flaky bimetallic oxide Bi2O3-CeO2.

2. The method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction according to claim 1, characterized in that: In the step 1, in solution A, the mass volume ratio of the single-layer graphene oxide, high-purity water, formic acid, and ammonium formate is 5-20 mg: 50-200 ml: 1-5 g: 90-360 μL.

3. The method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction according to claim 1, characterized in that: In the step 1, the stirring and dispersing time is 24 to 48 hours, and the ultrasonic dispersing time is 1 to 2 hours.

4. The method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction according to claim 1, characterized in that: In the step 2, in solution B, the mass volume ratio of Bi(NO3)3·5H2O, Ce(NO3)3·6H2O and high-purity water is 0.24-1g:0.6-2.4g:20-100mL.

5. The method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction according to claim 1, characterized in that: In the step 3, the preheating temperature of the oil bath is 75-85° C., the dropping speed of solution B is 5-10 ml / min, the insulation time is 1-2 h, and the freeze-drying time is 24-48 h.

6. The method for preparing a sheet-like bimetallic oxide for electrochemical uranium extraction according to claim 1, characterized in that: In the step 4, the heating rate of the pyrolysis oxidation is 1 to 5°C / min, the pyrolysis oxidation temperature is 650 to 750°C, and the insulation time is 2 to 6 hours.

7. Application of a flaky bimetallic oxide in nuclear wastewater treatment, wherein the flaky bimetallic oxide is prepared by the method for preparing a flaky bimetallic oxide for electrochemical uranium extraction according to any one of claims 1 to 6, characterized in that: The flaky bimetallic oxide is used as a catalyst for electrochemical uranium extraction in nuclear wastewater treatment. The flaky bimetallic oxide is loaded on a carbon felt electrode as a working electrode to electrochemically extract uranium from uranium-containing nuclear wastewater. The specific method includes: S1. Dispersing the flaky bimetallic oxide as a catalyst in a mixed solution of anhydrous ethanol and Nafion solution and ultrasonically treating it to obtain a homogeneous catalyst solution, ultrasonically treating the carbon felt with a mixture of ethanol and deionized water, and then immersing the carbon felt in the homogeneous catalyst solution for 6 to 12 hours, taking it out and drying it to achieve the loading of the flaky bimetallic oxide on the carbon felt, and in a conventional three-electrode system of an electrochemical workstation, using a fluorine-containing uranium-containing solution as a nuclear waste water simulation solution, using a platinum wire and Ag / AgCl as a counter electrode and a reference electrode, respectively, and using a carbon felt electrode as a working electrode, an electrochemical uranium extraction experiment is performed; S2. Place the working electrode after electrochemical uranium extraction in a sodium carbonate electrolyte, apply a constant positive potential, desorb the working electrode, and place the desorbed working electrode again in a simulated nuclear waste water solution to conduct a cyclic uranium extraction experiment; then conduct electrochemical uranium extraction experiments at different pH values ​​and under different interfering ions according to the method of S1.

8. The use of the flaky bimetallic oxide according to claim 7 in nuclear waste water treatment, characterized in that: In S1, the mass volume ratio of catalyst, anhydrous ethanol and Nafion solution is 5-20 mg: 2-8 ml: 10-30 uL, the ultrasonic treatment time is 10-20 min, and the loading amount of catalyst is fixed at 3-5 mg / cm 2 .

9. The use of the flaky bimetallic oxide according to claim 7 in nuclear waste water treatment, characterized in that: In the S2, the constant positive potential is 1-2V.

10. The use of the flaky bimetallic oxide in nuclear waste water treatment according to claim 7, characterized in that: In S1, UO2 in the simulated nuclear wastewater solution 2+ Concentration ≥ 100 mg / L, F - Concentration ≥30g / L.

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