A material for uranium extraction, a method of preparation and an extraction method

Abstract

The application belongs to the technical field of water pollution treatment, and particularly relates to a material for uranium extraction, a preparation method and an extraction method. The material for uranium extraction is a doped BiFeO3 material, and the doping substance is a Sm-Mn mixture, a La-Co mixture, In2Se3 or g-C3N4. The application improves the extraction rate of uranium.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water pollution treatment, and particularly relates to a material for uranium extraction, a preparation method and an extraction method. BACKGROUND

[0002] Environment and energy are closely related to human life and social development. Nuclear energy, as a clean and green energy source, can alleviate dependence on fossil fuels and reduce greenhouse gas emissions. Uranium (U) is the most important element for nuclear energy utilization due to its high energy density. A large amount of uranium-containing U(VI) water may be produced during the mining and use of uranium, which may cause serious pollution and resource waste if discharged without treatment. In addition, uranium element U(VI) exists in seawater, and its reserves are about 1000 times those of land. Therefore, the extraction of U(VI) from uranium-containing water has become one of the central issues of energy saving, environmental management and green energy development.

[0003] At present, there are many methods for the extraction of U(VI) from uranium-containing water, such as chemical precipitation, organic solvent extraction, evaporation concentration, ion exchange, adsorption, etc. However, in practical application, all these methods have various problems, such as large amount of reagent energy consumption and easy production of secondary U(Ⅵ) substances, etc. Recently, photocatalytic technology using sunlight to degrade pollutants is considered as a green technology to solve current energy and environmental problems. However, the separation efficiency of photo-generated electron-hole pairs is usually low. Therefore, an effective method of band modulation and charge separation is still to be explored for photocatalysts. In recent years, the introduction of piezoelectric ferroelectric semiconductors has shown high catalytic activity in photocatalytic reactions, which is mainly due to the polarization electric field promoting the separation and transfer of photo-generated carriers. The polarization electric field strength generated by piezoelectric ferroelectric materials is much larger than the built-in electric field strength generated by heterojunctions, and is controllable, which helps to regulate the band structure of photocatalysts and more effectively accelerate the separation and transfer of photo-generated carriers, thereby improving their catalytic activity. On the one hand, under the action of mechanical force, the non-equilibrium surface charge and polarization electric field of piezoelectric materials themselves can trigger electrochemical reactions, thereby triggering a series of reactions to realize piezoelectric catalysis. On the other hand, the polarization electric field induced by mechanical force can provide sufficient driving force for the bulk and surface separation of photo-generated carriers, so that electrons and holes will be quickly attracted to the surface of the catalyst to improve the separation efficiency of photo-generated carriers. At the same time, this polarization electric field will also cause the conduction band and valence band of the photocatalyst to tilt, promoting the extension of the charge lifetime, thereby helping to improve its catalytic performance. Therefore, through piezoelectric catalysis and piezoelectric photocatalysis, the catalytic reduction of U(VI) in uranium water can be effectively improved.

[0004] Traditional piezoelectric materials possess excellent insulation and a wide band gap, which makes it difficult for electrons to transition from the valence band to the conduction band. Furthermore, the number of free charge carriers available under thermal equilibrium is limited, thus limiting their application as photocatalysts. Bismuth ferrite (BiFeO3), a non-toxic, harmless, and environmentally friendly perovskite-structured multiferroic material, has a band gap of approximately 2.2 eV, making it more advantageous for absorbing solar light compared to traditional ferroelectric or piezoelectric materials. Due to its narrow band gap, tunable electronic structure, and high light absorption coefficient, BiFeO3 exhibits excellent photocatalytic performance in the visible and ultraviolet light ranges. In addition, BiFeO3 also possesses piezoelectric effects and spontaneous polarization characteristics, with a maximum spontaneous polarization intensity exceeding 100 μC / cm. 2 piezoelectric coefficient (d 33 With a heat capacity of approximately 100 pm / V, and good chemical and structural stability as well as radiation resistance, BiFeO3 is an ideal material for simultaneously and effectively utilizing both light and mechanical energy.

[0005] Patent application publication number CN 112342385 A discloses an apparatus, method and application for extracting uranium from uranium-containing wastewater or seawater. It uses TiO2, Fe2O3, ZnO, Cu2O, CdS, g-C3N4 or BiFeO3 for photocatalysis. When TiO2 is used, the uranium removal efficiency reaches 42%, which needs to be further improved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a material, preparation method and extraction method for uranium extraction, thereby improving the uranium extraction rate.

[0007] This invention provides a material for uranium extraction, wherein the material for uranium extraction is a doped BiFeO3 material, and the dopant is a mixture of Sm and Mn, a mixture of La and Co, In2Se3 or g-C3N4.

[0008] Preferably, the molar ratio of the Sm, Mn mixture and BiFeO3 is 1:8-12, and the molar ratio of Sm and Mn is 1-2:1-2; the molar ratio of the La, Co mixture and BiFeO3 is 1:8-12, and the molar ratio of La and Co is 1-2:1-2.

[0009] Preferably, the molar ratio of In2Se3 to BiFeO3 is 1-6:20, and the molar ratio of g-C3N4 to BiFeO3 is 1-4:20.

[0010] This invention provides a method for preparing the material for uranium extraction, wherein bismuth nitrate, ferric nitrate and dopant are mixed, reacted in an alkaline environment, centrifuged, washed and dried to obtain the material for uranium extraction; the dopant is a mixture of samarium nitrate and manganese acetate, In2Se3, g-C3N4, or a mixture of lanthanum nitrate and cobalt nitrate.

[0011] Optionally, the solvent used when mixing bismuth nitrate, ferric nitrate, and the dopant is a nitric acid solution.

[0012] Optionally, sodium hydroxide is added to form the alkaline environment.

[0013] Optionally, the reaction temperature is 160-200℃.

[0014] Optionally, the washing solution is ethanol and deionized water.

[0015] This invention provides an extraction method for uranium extraction, comprising the following steps: adding the material for uranium extraction to a solution containing uranium, adjusting the pH value to 4-5.5 (preferably 5, the adjusting substance being hydrochloric acid (concentration can be 0.1mol / L) or ammonia water), mixing evenly in a dark environment, and precipitating uranyl ions under mechanical force to separate them from the solution, thereby extracting uranium.

[0016] Optionally, the mechanical force is ultrasonic oscillation, with a power of 80-200 W (preferably 100 W) and a frequency of 28-50 kHz (preferably 40 kHz); during the application of the mechanical force, light radiation treatment is also included, with a light intensity of 300-500 mW / cm².

[0017] The beneficial effect of this invention is that the BiFeO3 material doped with this invention can reduce the easily migratable uranium U(VI) in low-concentration uranium solutions to the insoluble and difficult-to-migrate U(IV), which can be used for uranium extraction.

[0018] This invention provides a method for treating uranium-containing U(VI) water using piezoelectric photocatalytic reduction of a material for uranium extraction. Through a series of comparative experiments, the feasibility of extracting uranium from U(VI) water using doped BiFeO3 materials via piezoelectric catalysis and piezoelectric photocatalytic reduction is demonstrated, achieving a maximum extraction rate of up to 99.6% U(VI) from the uranium-containing U(VI) aqueous solution. The mechanism of this invention is based on the piezoelectric effect and piezoelectric photoelectron effect. Under mechanical force (such as ultrasonic oscillation), the non-equilibrium surface charge and polarized electric field accumulated in the doped BiFeO3 material can initiate electrochemical reactions, thereby triggering a series of reactions to achieve piezoelectric catalysis. When external light and mechanical stress are applied to the material simultaneously, photogenerated electron-hole pairs are generated. Under the action of mechanical vibration, the piezoelectric material deforms, leading to polarization and thus forming a built-in electric field. Piezoelectric photocatalysis can utilize this built-in electric field to accelerate the separation of photogenerated carriers, effectively improving catalytic activity. This method further reduces U(VI) in uranium-containing U(VI) water to a precipitate U(Ⅳ) compound, thus extracting U(VI). It effectively utilizes environmental mechanical energy such as noise, waves, vibration, and sunlight to extract uranium (U(VI)) from the solution. Furthermore, the piezoelectric photocatalytic reduction method using doped BiFeO3 materials offers advantages such as high selectivity, non-toxicity, low energy consumption, and the ability to be carried out at room temperature and pressure. Attached Figure Description

[0019] Figure 1 The extraction rate of uranium from Sm and Mn-doped BiFeO3 under ultrasonic oscillation (piezoelectric catalysis) is given.

[0020] Figure 2 The extraction rate of uranium by the BiFeO3 / In2Se3 composite catalyst material under ultrasonic oscillation (piezoelectric catalysis) is given.

[0021] Figure 3 The extraction rates of uranium from BiFeO3 / In2Se3 composite catalysts under ultrasonic oscillation (piezoelectric catalysis) and ultrasonic oscillation combined with light irradiation (piezoelectric-photocatalysis) are measured.

[0022] Figure 4 The extraction rate of uranium by the BiFeO3 / g-C3N4 composite catalyst material under ultrasonic oscillation (piezoelectric catalysis) is given.

[0023] Figure 5 The extraction rate of uranium from La and Co-doped BiFeO3 under ultrasonic oscillation (piezoelectric catalysis) is given. Detailed Implementation

[0024] Example 1 Preparation of BiFeO3 3 mmol of bismuth nitrate (Bi(NO3)3•5H2O) was dissolved in 20 mL of 1 mol / L nitric acid solution and stirred until homogeneous. Then, 3 mmol of ferric nitrate (Fe(NO3)3•9H2O) was added, and the mixture was magnetically stirred for 30 min. Next, 50 mL of 2 mol / L NaOH solution was added, and the mixture was stirred for 60 min to obtain a dark brown suspension. This suspension was poured into a reaction vessel lined with polytetrafluoroethylene and reacted at 180 °C for 72 h. The resulting product was centrifuged, washed three times each with ethanol and deionized water, and dried in a vacuum drying oven for 12 h to obtain BiFeO3 powder.

[0025] Example 2 Preparation of Sm-doped BiFeO3 2.7 mmol of bismuth nitrate (Bi(NO3)3•5H2O) was dissolved in 20 mL of 1 mol / L nitric acid solution. After stirring until homogeneous, 3 mmol of ferric nitrate (Fe(NO3)3•9H2O) and 0.3 mmol of samarium nitrate (Sm(NO3)3•6H2O) were added. The mixture was magnetically stirred for 30 min, and then 50 mL of 2 mol / L NaOH solution was added. The mixture was stirred for 60 min to obtain a dark brown suspension. This suspension was poured into a reaction vessel lined with polytetrafluoroethylene and reacted at 180 °C for 72 h. The resulting product was centrifuged, washed three times each with ethanol and deionized water, and dried in a vacuum drying oven for 12 h to obtain Sm-doped BiFeO3 powder with an Sm molar ratio of 10%.

[0026] Example 3 Preparation of Mn-doped BiFeO3 powder 3 mmol of bismuth nitrate (Bi(NO3)3•5H2O) was dissolved in 20 mL of 1 mol / L nitric acid solution. After stirring until homogeneous, 2.7 mmol of ferric nitrate (Fe(NO3)3•9H2O) and 0.3 mmol of manganese acetate (Mn(CH3COO)2•4H2O) were added. The mixture was magnetically stirred for 30 min, and then 50 mL of 2 mol / L NaOH solution was added. The mixture was stirred for 60 min to obtain a dark brown suspension. This suspension was poured into a reaction vessel lined with polytetrafluoroethylene and reacted at 180 °C for 72 h. The resulting product was centrifuged, washed three times each with ethanol and deionized water, and dried in a vacuum drying oven for 12 h to obtain Mn-doped BiFeO3 powder with a Mn molar ratio of 10%.

[0027] Example 4 Preparation of Sm, Mn co-doped BiFeO3 2.7 mmol of bismuth nitrate (Bi(NO3)3•5H2O) was dissolved in 20 mL of 1 mol / L nitric acid solution. After stirring, 2.7 mmol of ferric nitrate (Fe(NO3)3•9H2O), 0.3 mmol of samarium nitrate (Sm(NO3)3•6H2O), and 0.3 mmol of manganese acetate (Mn(CH3COO)2•4H2O) were added. The mixture was magnetically stirred for 30 min, and then 50 mL of 2 mol / L NaOH solution was added. The mixture was stirred for 60 min to obtain a dark brown suspension. This suspension was poured into a reaction vessel lined with polytetrafluoroethylene and reacted at 180 °C for 72 h. The resulting product was centrifuged, washed three times each with ethanol and deionized water, and dried in a vacuum drying oven for 12 h to obtain Sm,Mn co-doped BiFeO3 powder with a molar ratio of 10%.

[0028] Example 5 This embodiment describes a method for extracting U(VI) from uranium U(VI) solution using Sm, Mn co-doped BiFeO3 piezoelectric catalyst, comprising the following steps: 1) Sm, Mn co-doped BiFeO3 materials were prepared by hydrothermal method (as in Example 4); 2) 50 mg of nano-Sm,Mn co-doped BiFeO3 material was added to 50 mL of uranium U(VI) aqueous solution. The pH of the solution was adjusted to 5 with 0.1 mol / L HCl, and the solution was placed in a 20 ºC constant-temperature ultrasonic cleaner (ultrasonic oscillation power of 100 W and frequency of 40 kHz). The uranium concentration in the uranium-containing U(VI) aqueous solution was 20 mg / L. The uranium concentration in the uranium-containing U(VI) aqueous solution was measured every 30 min. The experimental results showed that Sm,Mn co-doped BiFeO3 could fix U(VI) in the U(VI) aqueous solution, up to a maximum of 99.3%.

[0029] The extraction performance of the doped BiFeO3 materials from Examples 2-3 was tested according to the method described in Example 5, and the results were as follows: Figure 1 As shown in the uranium extraction rates, it can be seen that the extraction rate of the doped BiFeO3 material in Example 4 is higher than that of the doped BiFeO3 materials in Examples 2-3.

[0030] Example 6 BiFeO3 / In2Se3 composite material Dissolve 3 mmol of bismuth nitrate (Bi(NO3)3•5H2O) in 20 ml of 1 mol / L nitric acid solution, stir well, and then add 3 mmol of ferric nitrate (Fe(NO3)3•9H2O), and a certain concentration of In2Se3 powder (controlling the molar ratio of In2Se3 to BiFeO3 to be 1:20, 2:20, 4:20, and 6:20, respectively).Figure 2 The BiFeO3 / In2Se3-1 mixture (i.e., the molar ratio of In2Se3 to BiFeO3 is 1:20, and so on) was magnetically stirred for 30 min, then 50 ml of a 2 mol / L NaOH solution was added, and the mixture was stirred for 60 min to obtain a suspension. This suspension was then poured into a reaction vessel lined with polytetrafluoroethylene (PTFE) and reacted at 180 °C for 72 h. The resulting product was centrifuged, washed three times each with ethanol and deionized water, and dried in a vacuum drying oven for 12 h to obtain the BiFeO3 / In2Se3 composite material.

[0031] Example 7 This embodiment describes a method for extracting U(VI) from uranium U(VI) solution using a BiFeO3 / In2Se3 composite material, including the following steps: 1) BiFeO3 / In2Se3 composite material was prepared using the hydrothermal method of Example 6; 2) 50 mg of the BiFeO3 / In2Se3 composite material was added to 50 mL of uranium U(VI) aqueous solution. The pH of the solution was adjusted to 5 with 0.1 mol / L HCl, and the solution was placed in a 20 ºC constant-temperature ultrasonic cleaner (ultrasonic oscillation power of 100 W and frequency of 40 kHz). The uranium concentration in the uranium-containing U(VI) aqueous solution was 20 mg / L. The uranium concentration in the uranium-containing U(VI) aqueous solution was measured every 30 min. The experimental results show that the BiFeO3 / In2Se3 composite material can fix U(VI) in the U(VI) aqueous solution. Specific results are as follows: Figure 2 As shown, the extraction rate is highest, reaching 98.0%, when the molar ratio of In2Se3 to BiFeO3 is 4:20.

[0032] Example 8 Based on Example 7, the molar ratio of In₂Se₃ and BiFeO₃ was controlled at 4:20. While placed in a 20°C constant-temperature ultrasonic cleaner, the mixture was also subjected to light radiation treatment, with the light intensity controlled at 300-500 mW / cm². The results were compared with the extraction method without light radiation treatment. Figure 3 As shown, it can be seen that the maximum efficiency can reach 98.8% under the combined effect of ultrasonic oscillation and light irradiation.

[0033] Example 9 Referring to Example 6, In2Se3 was replaced with g-C3N4, and the molar ratio of g-C3N4 to BiFeO3 was controlled to be 1:10. Other aspects were the same as in Example 6, and g-C3N4 / BiFeO3 composite material was prepared.

[0034] Uranium U(VI) was extracted according to the method described in Example 7, and the experimental results are as follows: Figure 4As shown.

[0035] Example 10 Following the same procedure as in Example 2, samarium nitrate was replaced with lanthanum nitrate, manganese acetate was replaced with cobalt nitrate, and all other aspects were the same as in Example 2, to prepare a cobalt / BiFeO3 composite material.

[0036] Uranium (U(VI)) was extracted according to the method described in Example 5, and the experimental results are as follows: Figure 5 As shown.

[0037] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0038] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A material for uranium extraction, characterized in that, The material used for uranium extraction is a doped BiFeO3 material, and the dopant is a mixture of Sm and Mn, a mixture of La and Co, In2Se3, or g-C3N4.

2. The material as described in claim 1, characterized in that, The molar ratio of the Sm, Mn mixture and BiFeO3 is 1:8-12, and the molar ratio of Sm and Mn is 1-2:1-2; the molar ratio of the La, Co mixture and BiFeO3 is 1:8-12, and the molar ratio of La and Co is 1-2:1-2.

3. The material as described in claim 1, characterized in that, The molar ratio of In2Se3 to BiFeO3 is 1-6:20; the molar ratio of g-C3N4 to BiFeO3 is 1-4:

20.

4. A method for preparing a material for uranium extraction as described in any one of claims 1-3, characterized in that, Bismuth nitrate, ferric nitrate, and dopant are mixed and reacted in an alkaline environment. The mixture is then centrifuged, washed, and dried to obtain a material for uranium extraction. The dopant is a mixture of samarium nitrate and manganese acetate, In2Se3, g-C3N4, or a mixture of lanthanum nitrate and cobalt nitrate.

5. The preparation method according to claim 4, characterized in that, The solvent used when mixing bismuth nitrate, ferric nitrate, and doping materials is a nitric acid solution.

6. The preparation method according to claim 4, characterized in that, Sodium hydroxide is added to create the alkaline environment.

7. The preparation method according to claim 4, characterized in that, The reaction temperature is 160-200℃.

8. The preparation method according to claim 4, characterized in that, The washing solution is ethanol and deionized water.

9. An extraction method for uranium extraction, characterized in that, The steps are as follows: add the material for uranium extraction as described in any one of claims 1-3 to a solution containing uranium, adjust the pH value to 4-5.5, mix evenly in a dark environment, and precipitate uranyl ions under mechanical force to separate them from the solution, thereby extracting uranium.

10. The extraction method for uranium extraction as described in claim 9, characterized in that, The mechanical force is ultrasonic oscillation, with a power of 80-200 W and a frequency of 28-50 kHz; during the application of the mechanical force, light radiation treatment is also included, with a light intensity of 300-500 mW / cm².

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