A cone self-assembled copper microsphere electrode for removing uranium in water and a preparation method and application thereof

Abstract

The application provides a kind of cone self-assembly copper microsphere electrode for removing uranium in water and a preparation method and application thereof, and relates to the technical field of water treatment and environmental management.The electrode is prepared by liquid phase reaction of copper sulfate pentahydrate, tannic acid, sodium hydroxide and ascorbic acid to form Cu microspheres self-assembled by cone units, and further loaded on the surface of carbon paper to construct a cone self-assembly copper microsphere electrode.The electrode preparation process is simple, without complex template and high temperature treatment;efficient removal of uranium in water can be realized under low voltage condition of 0.8 V.In the process of electrochemical treatment, UO2 2+ is reduced to U3O8, the electrode has excellent anti-biofouling performance and practical water applicability, and has good application prospect.

Description

Technical Field

[0001] This invention relates to the field of water treatment and environmental governance technology, and in particular to a cone-shaped self-assembled copper microsphere electrode for removing uranium from water, its preparation method, and its application. Background Technology

[0002] Uranium exists primarily in water as highly soluble uranyl ions (UO2). 2+ Uranium exists in the form of (6-6 valences), where uranium is in the hexavalent state. Currently, the most widely used technology in the field of uranium removal is physicochemical adsorption, which mainly utilizes specific groups (such as geminitroxime groups, AO) on the adsorbent to react with UO2. 2+ Adsorption occurs via a method that employs external electric fields. However, this method suffers from drawbacks such as slow adsorption kinetics and insufficient adsorption capacity. In contrast, electrochemical techniques drive and regulate the adsorption of UO2 using an external electric field. 2+ The capture and reduction process fundamentally changes the traditional adsorption method's reliance on passive diffusion for mass transfer, thus significantly improving kinetics and capacity. However, existing electrochemical systems still face several limitations: firstly, the operating voltage is generally higher than 2 V, resulting in high energy consumption; secondly, the electrode fabrication process is complex and costly; and thirdly, biofouling caused by microbial attachment in complex aquatic environments can significantly reduce the electrode's uranium removal efficiency.

[0003] In summary, developing an electrochemical uranium removal electrode that is easy to prepare, low in cost, can operate efficiently under low voltage conditions, and has anti-biofouling properties for the efficient removal and recovery of uranium in water is of significant research importance and application value. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing electrochemical uranium removal technologies in water, such as complex electrode preparation processes, high costs, high operating voltages, and susceptibility to biofouling. It provides a method for preparing a cone-shaped self-assembled Cu microsphere electrode that is simple to prepare, low in cost, can operate efficiently at low voltages, and has excellent resistance to biofouling, as well as its application.

[0005] The technical solution of this invention is implemented as follows: A method for preparing a cone-shaped self-assembled copper microsphere electrode for uranium removal from water includes the following steps: S1: Mix copper sulfate and tannic acid in an aqueous solution, first allowing the tannic acid to react with the Cu... 2+ Coordination occurs and some Cu 2+ Reduced to Cu + Then, adjust the pH of the aqueous solution system to 8-10, and add ascorbic acid to mix, thus obtaining the reaction mixture system. S2: The reaction mixture is subjected to a sealed heating reaction. During this process, ascorbic acid further reacts Cu. +Reduced to Cu 0 Tannic acid adsorbed on Cu 0 The specific crystal facets inhibit growth in this direction, thereby forming a cone-shaped structural unit, which further self-assembles into microspheres. After the reaction is completed, the mixture is cooled to room temperature, and the reaction product is transferred to a centrifuge tube for centrifugation. The lower precipitate is collected. The precipitate is then washed multiple times with deionized water until the washing solution is neutral. Finally, it is washed with anhydrous ethanol and dried to obtain cone-shaped self-assembled copper microspheres for constructing electrodes. S3: Load the cone-shaped self-assembled copper microspheres onto the electrode substrate to obtain the cone-shaped self-assembled copper microsphere electrode for electrochemical removal of uranium.

[0006] A further embodiment is that the molar ratio of copper sulfate, tannic acid and ascorbic acid is 1:0.02~0.4:2~6.

[0007] A further embodiment is that the molar ratio of copper sulfate, tannic acid and ascorbic acid is 1:0.08~0.25:3~5.

[0008] A further option is that, in step S1, the pH of the aqueous solution system is adjusted to 8-10 using an alkaline solution, wherein the concentration of the alkaline solution is 0.5-1.0 mol / L; The alkaline solution is a sodium hydroxide solution and / or a potassium hydroxide solution.

[0009] A further embodiment is that the heating reaction temperature is 80 ℃~90 ℃, and the reaction time is 1~5 h; The heating reaction process also includes stirring at a speed of 300~1000 r / min.

[0010] A further embodiment is that, in step S3, the self-assembled copper microspheres of the cone, acetylene black, 5 wt.% Nafion solution and anhydrous ethanol are used to prepare an electrode slurry. The electrode slurry is then coated onto an electrode substrate at 60 ℃~80 ℃ and dried to obtain the self-assembled copper microsphere electrode of the cone. The electrode substrate includes carbon paper, carbon cloth, graphite sheet or titanium sheet. The mass-to-volume ratio of the self-assembled copper microspheres, acetylene black, 5 wt.% Nafion solution, and anhydrous ethanol in the cone is 1~2 mg: 0.1~0.3 mg: 1~5 μL: 10~30 μL; This invention provides a cone-shaped self-assembled copper microsphere prepared by the preparation method described above.

[0011] The present invention also provides a cone-shaped self-assembled copper microsphere electrode prepared by the preparation method described above.

[0012] This invention provides an application of the above-described cone-shaped self-assembled copper microsphere or the above-described cone-shaped self-assembled copper microsphere electrode in the electrochemical removal of uranium from water.

[0013] This invention provides a method for electrochemical removal of uranium from water, the specific method of which is as follows: The self-assembled Cu microsphere electrode with a cone shape was used as the working electrode, and a graphite rod was used as the auxiliary electrode. An electrochemical treatment system was constructed by placing the electrode in an aqueous solution containing uranium. An electrochemical treatment was performed by applying a voltage of 0.2~1.0 V, which caused U(VI) to be enriched and reduced and precipitated, thereby achieving efficient removal and recovery of uranium in water. Alternatively, the conical self-assembled copper microspheres can be loaded onto an electrode substrate to obtain a conical self-assembled copper microsphere electrode. The conical self-assembled copper microsphere electrode can be used as the working electrode, and a graphite rod can be used as the auxiliary electrode. The electrode is placed in a uranium-containing aqueous solution to construct an electrochemical treatment system. A voltage of 0.2~1.0 V is applied for electrochemical treatment to enrich and reduce U(VI) precipitation, thereby achieving efficient removal and recovery of uranium from water. The water body includes tap water, groundwater, surface water, or seawater.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation process of the cone self-assembled Cu microsphere electrode of the present invention is simple, the raw materials used are inexpensive, and no complex templates or high-temperature calcination are required in the preparation of active components. The electrode construction method is simple and has good potential for scale-up preparation and practical application.

[0015] (2) The cone-shaped self-assembled Cu microspheres loaded on the electrode surface of the present invention are formed by the self-assembly of multiple cone-shaped structural units. The cone-shaped units form abundant micro- and nano-channels, which can provide UO2. 2+ It provides ample electrochemical reaction sites, thereby enhancing the reduction effect of the electrode on uranium; when used as a working electrode to treat a 20 mg / L uranium-containing solution, it can reach the removal equilibrium within 30 min, with a uranium removal efficiency of up to 95.9%.

[0016] (3) The cone-shaped self-assembled Cu microsphere electrode of the present invention has good antibacterial and anti-biofouling properties, which can effectively inhibit the attachment and reproduction of microorganisms in water on the electrode surface, and is conducive to maintaining the stable uranium removal performance of the electrode in complex water environment.

[0017] (4) The cone-shaped self-assembled Cu microsphere electrode of the present invention can achieve efficient removal of uranium at a low applied voltage. Its preferred working voltage is only 0.8 V, which is lower than the working voltage of more than 2 V in the existing electrochemical uranium removal system, which is beneficial to reduce the energy consumption of the electrochemical process.

[0018] (5) During the electrochemical treatment process, the UO2 in the water body2+ U3O8 precipitate can be formed on the electrode surface through reduction, thereby achieving the removal and enrichment of uranium and avoiding complex elution processes. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 These are scanning electron microscope (SEM) images of the active copper-based materials obtained in Example 1 and various comparative examples of the present invention; wherein, Figure 1 In this context, 'a' refers to the Micro-Cu prepared in Example 1. Figure 1 In the figure, b represents the VC-Cu prepared in Comparative Example 1. Figure 1 In this context, 'c' represents the C-Cu prepared in Comparative Example 2. Figure 1 In this context, d represents the Cu(B) prepared in Comparative Example 3. Figure 1 In this context, 'e' represents Cu2O prepared in Comparative Example 4.

[0021] Figure 2 The X-ray diffraction (XRD) patterns of Micro-Cu prepared in Example 1, Cu(B) prepared in Comparative Example 3, and Cu2O prepared in Comparative Example 4 are shown.

[0022] Figure 3 This is a graph showing the change in electrochemical uranium removal efficiency over time for the electrodes obtained in Example 1 and each comparative example of the performance test of this invention.

[0023] Figure 4 The graph shows the electrochemical uranium removal efficiency of the Micro-Cu electrode prepared in Example 1 of the 2nd performance test of the present invention under different voltages.

[0024] Figure 5 The graph shows the electrochemical uranium removal capacity performance of the Micro-Cu electrode prepared in Example 1 of Performance Test Example 3 of the present invention at different initial uranium concentrations.

[0025] Figure 6 This is a bar chart showing the electrochemical uranium removal efficiency of the Micro-Cu electrode prepared in Example 1 of Performance Test Example 4 of the present invention in various single interfering ion systems.

[0026] Figure 7 This is a comparison chart of the electrochemical uranium removal efficiency of the Micro-Cu electrode prepared in Example 1 of Performance Test Example 5 of the present invention in four actual water bodies: tap water, groundwater, surface water and seawater.

[0027] Figure 8 This is a graph showing the antibacterial performance of the Micro-Cu electrode against Escherichia coli and Staphylococcus aureus in Performance Test Example 6 of the present invention.

[0028] Figure 9 This is a characterization diagram of the uranium product obtained by electrochemical reduction in Performance Test Example 7 of the present invention; wherein, Figure 9 In the image, 'a' represents a transmission electron microscope (TEM) image. Figure 9 In this diagram, b represents the Raman spectrum; Figure 9 In the figure, c represents the fine X-ray photoelectron spectroscopy (XPS) spectrum of the U 4f orbital. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0031] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0032] Example 1 - Fabrication of a cone-shaped self-assembled Cu microsphere electrode (1) Add 1.24 g of copper sulfate pentahydrate to 10 mL of deionized water and sonicate until completely dissolved to obtain a 0.5 mol / L copper sulfate pentahydrate aqueous solution; add 1.06 g of tannic acid to 20 mL of deionized water and sonicate until completely dissolved to obtain a 0.03 mol / L tannic acid aqueous solution; add 0.64 g of sodium hydroxide to 20 mL of deionized water and sonicate until completely dissolved to obtain a 0.8 mol / L sodium hydroxide aqueous solution; add 3.52 g of ascorbic acid to 20 mL of deionized water and sonicate until completely dissolved to obtain a 1 mol / L ascorbic acid aqueous solution.

[0033] (2) Under continuous magnetic stirring, the copper sulfate pentahydrate aqueous solution and tannic acid aqueous solution are mixed evenly, and then the sodium hydroxide aqueous solution is added dropwise to adjust the pH of the mixed system to 8-9. Then the ascorbic acid aqueous solution is added and mixed evenly to obtain the reaction mixture system.

[0034] (3) Transfer the reaction mixture obtained in step (2) into a thick-walled pressure-resistant glass bottle and seal it. Place it in an oil bath at 80°C and heat it for 2 h under magnetic stirring at a stirring speed of 600 r / min. (4) After the reaction is completed, cool to room temperature, transfer the reaction product to a centrifuge tube, centrifuge at 6000 rpm, and collect the lower precipitate. Then wash the precipitate with deionized water several times until the washing solution is neutral, and wash it with anhydrous ethanol for the last time. After washing, place the precipitate in a vacuum oven at 60 ℃ and dry for 6 h to obtain a cone-shaped self-assembled Cu microsphere for constructing the electrode, named Micro-Cu.

[0035] (5) The Micro-Cu, acetylene black, 5 wt.% Nafion solution and anhydrous ethanol obtained in step (4) are mixed evenly in a ratio of 1 mg: 0.2 mg: 2 μL: 20 μL to form an electrode slurry; then the electrode slurry is drop-coated onto the surface of carbon paper on a 70 ℃ heating plate and dried to obtain a cone-shaped self-assembled Cu microsphere electrode for electrochemical removal of uranium, named Micro-Cu electrode.

[0036] Comparative Example 1 - Control electrode prepared without the addition of tannic acid Except for the absence of tannic acid in Example 1 and the use of an equal volume of deionized water instead of tannic acid aqueous solution, the other raw material ratios, solution addition order, pH control, oil bath reaction temperature and time, centrifugation speed, washing and drying processes were all the same as in Example 1, resulting in a Cu product prepared without the addition of tannic acid, which was named VC-Cu.

[0037] Subsequently, following the same electrode slurry preparation and drop-coating method as in Example 1, VC-Cu was loaded onto the surface of carbon paper to obtain a VC-Cu control electrode.

[0038] Comparative Example 2 - Commercial Cu Microspheres Comparative Electrode Commercial Cu microspheres purchased from Shanghai Aladdin Reagent Co., Ltd. were used as the comparative active component. The purity of the commercial Cu microspheres was ≥99.9%, the particle size was about 1 μm, and they were named C-Cu.

[0039] Subsequently, following the same electrode slurry preparation and drop-coating method as in Example 1, C-Cu was loaded onto the surface of carbon paper to obtain a C-Cu control electrode.

[0040] Comparative Example 3-Cu Nanoparticle Contrast Electrode Copper nanoparticles were prepared according to the synthesis method disclosed in Comparative Example 1 of application publication number CN 117626015 A: 0.37 mol / L copper chloride solution and 5 mol / L sodium borohydride solution were prepared using deionized water at 0 ℃; 2 mL of copper chloride solution was quickly added to 2 mL of sodium borohydride solution, and the reaction was carried out under ice-water bath conditions until no bubbles were generated; after the reaction was completed, the mixture was filtered, washed three times each with deionized water and acetone, and dried under vacuum at 60 ℃ for 12 h to obtain copper nanomaterials, named Cu(B).

[0041] Subsequently, following the same electrode slurry preparation and drop-coating method as in Example 1, Cu(B) was loaded onto the surface of carbon paper to obtain a Cu(B) control electrode.

[0042] Comparative Example 4 - Cu2O microsphere contrast electrode 0.96 g of copper sulfate pentahydrate was dissolved in 20 mL of deionized water to obtain solution A; 0.80 g of sodium hydroxide was dissolved in 20 mL of deionized water to obtain solution B; 1.29 g of glucose was dissolved in 20 mL of deionized water to obtain solution C; solution A was slowly poured into solution B and heated to 70℃; then solution C was added, and the reaction was allowed to proceed for 30 min; after the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed with deionized water and anhydrous ethanol, and dried to obtain cuprous oxide microspheres, which were named Cu2O.

[0043] Subsequently, following the same electrode slurry preparation and drop-coating method as in Example 1, Cu2O was loaded onto the surface of carbon paper to obtain a Cu2O control electrode.

[0044] Material characterization The microstructure of the electrode active components obtained in Example 1 and each comparative example was observed using scanning electron microscopy (SEM). Figure 1 As shown in Figure a, the Micro-Cu obtained in Example 1 exhibits a microsphere structure formed by the self-assembly of multifaceted pyramidal units, with a particle size of approximately 4 μm. Abundant micro- and nano-channels are formed between the pyramidal units, which facilitates the exposure of more electrochemical reaction sites and promotes the mass transfer of uranyl ions. Figure 1 As shown in b, the VC-Cu obtained in Comparative Example 1 without the addition of tannic acid mainly exhibits an octahedral structure and does not form the regular cone-shaped self-assembled microsphere structure as in Example 1, indicating that tannic acid plays an important role in regulating the growth of Cu crystal faces and the formation of cone-shaped self-assembled structures.

[0045] In addition, such as Figure 1 As shown in c in Comparative Example 2, the commercial Cu microspheres C-Cu are solid microspheres with an average particle size of approximately 1 μm; Figure 1 As shown in d, the Cu(B) obtained in Comparative Example 3 is in the form of nanoparticles; as Figure 1 As shown in e, the Cu2O obtained in Comparative Example 4 is a solid spherical structure with a size of approximately 4 μm.

[0046] The above results indicate that the Micro-Cu obtained in Example 1 has a cone-shaped self-assembled microsphere structure that differs from the comparative examples, and its abundant micro-nano channel structure is beneficial for constructing an efficient electrochemical uranium removal interface.

[0047] The crystal structures of the active components obtained in Example 1, Comparative Example 3, and Comparative Example 4 were characterized using X-ray diffraction (XRD). Figure 2 As shown, the Micro-Cu obtained in Example 1 exhibits characteristic diffraction peaks of typical face-centered cubic metallic Cu, which are consistent with the standard card PDF#04-0836, indicating that the obtained Micro-Cu is mainly metallic Cu phase. The Cu(B) obtained in Comparative Example 3 is prone to oxidation due to the lack of a protective agent during preparation, thus exhibiting some diffraction peaks attributed to Cu2O; the diffraction peaks of Cu2O obtained in Comparative Example 4 are consistent with the Cu2O standard card PDF#05-0667.

[0048] The results above indicate that Example 1 successfully prepared a metal Cu microsphere with a cone-shaped self-assembled structure.

[0049] [Performance Test Example 1] Comparison of electrochemical uranium removal efficiency between Example 1 and various comparative examples Test method: Using the Micro-Cu electrode obtained in Example 1 and the comparative electrodes obtained in each comparative example as working electrodes, and graphite rods as auxiliary electrodes, an electrochemical uranium removal system was constructed. Uranyl nitrate hexahydrate UO2(NO3)2·6H2O was dissolved in deionized water to prepare a uranium-containing solution with an initial U(VI) concentration of 20 mg / L. The mass ratio of the active component loaded in the electrode to the volume of the uranium-containing solution was controlled at 0.05 g:1 L. A voltage of 0.8 V was applied, and the electrochemical uranium removal experiment was carried out at room temperature for 60 min. After the reaction, the solution was filtered through a 0.22 μm filter membrane, and the uranium concentration in the solution was determined by the azoarsine method using a UV-Vis spectrometer.

[0050] The results are as follows Figure 3As shown, under the same test conditions, the Micro-Cu electrode obtained in Example 1 exhibited the highest uranium removal efficiency and the fastest removal kinetics, reaching removal equilibrium within 30 min with a uranium removal efficiency as high as 95.9%. In contrast, the VC-Cu electrode obtained in Comparative Example 1 had a uranium removal efficiency of 25.3% within 30 min; the C-Cu electrode obtained in Comparative Example 2 had a uranium removal efficiency of only 12.9% within 30 min; the Cu(B) electrode obtained in Comparative Example 3 had a uranium removal efficiency of 64.4% within 30 min, reaching 78.4% at equilibrium; and the Cu2O electrode obtained in Comparative Example 4 exhibited lower electrochemical uranium removal activity, with a removal efficiency of only 5.6% at 60 min.

[0051] The above results indicate that the cone-shaped self-assembled Cu microsphere electrode obtained in Example 1 has superior electrochemical uranium removal performance.

[0052] [Performance Test Example 2] Example 1: Electrochemical uranium removal efficiency at different voltages This test examines the electrochemical uranium removal efficiency of the Micro-Cu electrode prepared in Example 1 under different voltages. The test results are as follows: Figure 4 As shown, the electrochemical uranium removal efficiency gradually increased over 60 minutes with increasing voltage, reaching a peak at 0.8 V. Specifically, the removal efficiencies were 61.9%, 70.1%, 77.6%, 98.5%, and 93.9% at voltages of 0.2, 0.4, 0.6, 0.8, and 1.0 V, respectively.

[0053] The above results indicate that the Micro-Cu electrode obtained in Example 1 can achieve efficient removal of uranium from water at a relatively low voltage, with a preferred operating voltage of 0.8 V.

[0054] [Performance Test Example 3] Electrochemical uranium removal capacity of Example 1 This test investigated the electrochemical uranium removal capacity of the Micro-Cu electrode prepared in Example 1 under different initial U(VI) concentrations. The test results are as follows: Figure 5 As shown, when the initial uranium concentration increased from 5 mg / L to 80 mg / L, the electrochemical uranium removal efficiency of this system still reached 91.4% within 180 min, with an unsaturated capacity as high as 1462.4 mg g. -1 This indicates that the Micro-Cu electrode obtained in Example 1 has excellent uranium enrichment and removal capabilities.

[0055] [Performance Test Example 4] Electrochemical Uranium Removal Efficiency of Example 1 under Single Ion Interference This test investigated the effect of common coexisting ions in actual water bodies on the electrochemical uranium removal efficiency of the Micro-Cu electrode prepared in Example 1. The initial concentration of U(VI) was 20 mg / L, and 1000 mg / L of Li was added. + 、Rb + K + Ba 2+ 、Sr 2+ Ca 2+ Mg 2+ ; 20 mg / L Mn 2+ Zn 2+ Fe 2+ Co 2+ Ni 2+ VO3 - ; 1000 mg / L of F - ,Br - NO 3- SO4 2 CO3 2- As an interfering ion, and adjusting the system pH to 6, all other conditions were the same as in performance test example 1. The test results are as follows: Figure 6 As shown, even in the presence of various interfering ions, the uranium removal efficiency of the Micro-Cu electrode can still be stably maintained above 80% within 60 min, confirming that the Micro-Cu electrode has good resistance to ion interference and is suitable for electrochemical uranium removal in complex aquatic environments.

[0056] [Performance Test Example 5] Uranium Removal Performance in Different Aqueous Media To further verify the application potential of the Micro-Cu electrode obtained in Example 1 in real aquatic environments, the Micro-Cu electrode was used in electrochemical uranium removal experiments in four actual water media: tap water, groundwater (well water), surface water (river water), and seawater. After filtration through a 0.45 μm filter membrane, UO2(NO3)2·6H2O was added to each water body to adjust the initial U(VI) concentration to 10 mg / L. Other conditions were the same as in Performance Test Example 1. The test results are as follows: Figure 7 As shown, within 60 min, the uranium removal efficiency of the Micro-Cu electrode in tap water, groundwater, surface water and seawater reached 93.3%, 81.9%, 91.1% and 88.2%, respectively, indicating that the cone-shaped self-assembled Cu microsphere electrode of the present invention can achieve efficient and stable uranium removal in different actual water media.

[0057] [Performance Test Example 6] Antibacterial performance of Example 1 The antibacterial properties of the Micro-Cu electrode were investigated using an in vitro antibacterial experiment. Two widely distributed bacteria were selected: Escherichia coli (E. coli) E. coli ) and Staphylococcus aureus ( S. aureus The target was a carbon paper electrode (approximately 2 cm × 2 cm in area) containing 10 mg Micro-Cu. 1 × 10⁻⁶ mg of Micro-Cu was added. 6 10 mL of CFU / mL bacterial suspension was co-cultured at 37 °C for 16–24 h. The biofilm was then carefully washed off using PBS elution buffer. The obtained bacterial suspension was diluted to an appropriate concentration and then inoculated onto nutrient agar medium and incubated at 37 °C for 24 h. Results are as follows: Figure 8 As shown, compared with the blank control group carbon paper, the experimental group had almost no bacterial colony adhesion, indicating that the Micro-Cu electrode has an effective inhibitory effect on bacterial growth and has excellent anti-biofouling ability.

[0058] [Performance Test Example 7] Structural Characterization of Uranium Products The microstructure and phase characteristics of the reduced uranium product obtained after treatment with the Micro-Cu electrode in Performance Test Example 1 were characterized. Figure 9 In the image, 'a' is a TEM image of the uranium product, showing that it is in the form of nanoparticles. Figure 9 In the figure, b represents the Raman spectrum at 503 cm⁻¹. - ¹ and 806 cm - The characteristic peak at ¹ represents the vibrational mode of the UO bond in a typical U3O8; Figure 9 The c in the figure represents the XPS fine spectrum of the U 4f orbital, which shows that the valence state of uranium consists of part +5 and part +6 valence, consistent with the crystal structure characteristics of U3O8.

[0059] The above results indicate that U(VI) is reduced and recovered in the form of U3O8 without the need for complex elution steps.

[0060] Example 2 - Fabrication of a cone-shaped self-assembled Cu microsphere electrode (1) Add 1.24 g of copper sulfate pentahydrate to 10 mL of deionized water and sonicate until completely dissolved to obtain a 0.5 mol / L copper sulfate pentahydrate aqueous solution; add 0.7 g of tannic acid to 20 mL of deionized water and sonicate until completely dissolved to obtain a 0.02 mol / L tannic acid aqueous solution; add 0.64 g of sodium hydroxide to 20 mL of deionized water and sonicate until completely dissolved to obtain a 0.8 mol / L sodium hydroxide aqueous solution; add 3.52 g of ascorbic acid to 20 mL of deionized water and sonicate until completely dissolved to obtain a 1 mol / L ascorbic acid aqueous solution.

[0061] (2) Under continuous magnetic stirring, the copper sulfate pentahydrate aqueous solution and tannic acid aqueous solution are mixed evenly, and then the sodium hydroxide aqueous solution is added dropwise to adjust the pH of the mixed system to 8-9. Then the ascorbic acid aqueous solution is added and mixed evenly to obtain the reaction mixture system.

[0062] The subsequent steps are the same as in Example 1.

[0063] Example 3 - Fabrication of a cone-shaped self-assembled Cu microsphere electrode (1) Add 1.24 g of copper sulfate pentahydrate to 10 mL of deionized water and sonicate until completely dissolved to obtain a 0.5 mol / L copper sulfate pentahydrate aqueous solution; add 1.62 g of tannic acid to 20 mL of deionized water and sonicate until completely dissolved to obtain a 0.05 mol / L tannic acid aqueous solution; add 0.64 g of sodium hydroxide to 20 mL of deionized water and sonicate until completely dissolved to obtain a 0.8 mol / L sodium hydroxide aqueous solution; add 3.52 g of ascorbic acid to 20 mL of deionized water and sonicate until completely dissolved to obtain a 1 mol / L ascorbic acid aqueous solution.

[0064] (2) Under continuous magnetic stirring, the copper sulfate pentahydrate aqueous solution and tannic acid aqueous solution are mixed evenly, and then the sodium hydroxide aqueous solution is added dropwise to adjust the pH of the mixed system to 8-9. Then the ascorbic acid aqueous solution is added and mixed evenly to obtain the reaction mixture system.

[0065] The subsequent steps are the same as in Example 1.

[0066] Comparative Example 5 - Cu2O polycrystalline microspheres (contrast electrode) Cu₂O polycrystalline microspheres were prepared according to the synthesis method disclosed in Example 2 of application publication number CN107473258B. (1) Synthesis of copper hydroxide Add 19.2000g of anhydrous copper sulfate to a 1L single-necked flask and dissolve it with 504mL of deionized water. After the solution turns clear blue, add 96mL of 5M sodium hydroxide solution dropwise at a rate of 6mL / min and continue stirring for 60 minutes. Centrifuge at 10000r / min to separate the resulting dark blue suspension and wash the separated solid product once with deionized water.

[0067] (2) Synthesis of copper hydroxide-tannic acid The copper hydroxide obtained in step 1) was redispersed in 588 mL of deionized water to obtain a dispersion. While stirring, 12 mL of a 40 mg / mL tannic acid aqueous solution was added directly to the dispersion, and the reaction was continued for 60 minutes. The resulting dark green suspension was separated by centrifugation at 10000 rpm, and the separated solid product was washed once with deionized water.

[0068] (3) Reduction reaction The copper hydroxide tannic acid obtained in step 2) was redispersed in 80 mL of deionized water to form a dispersion. Under stirring, 120 mL of 0.5 M ascorbic acid aqueous solution was added dropwise to the dispersion at a rate of 5 mL / min. The reaction was continued for 2 hours at room temperature with stirring. The resulting orange suspension was separated by centrifugation at 12000 r / min. The separated product was washed three times with deionized water. The precipitate was collected after freeze-drying. Finally, polycrystalline microspheres assembled from cuprous oxide nanocrystals were obtained.

[0069] Subsequently, following the same electrode slurry preparation and drop-coating method as in Example 1, Cu2O polycrystalline microspheres were loaded onto the surface of carbon paper to obtain a Cu2O polycrystalline microsphere comparison electrode.

[0070] The test showed that when a voltage of 0.8 V was applied, the uranium removal efficiency was 5.8% after 60 minutes.

[0071] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a cone-shaped self-assembled copper microsphere electrode for removing uranium from water, characterized in that, Includes the following steps: S1: Mix copper sulfate and tannic acid into an aqueous solution, adjust the pH of the aqueous solution to 8-10, and then add ascorbic acid solution and mix to obtain a reaction mixture. The molar ratio of copper sulfate, tannic acid, and ascorbic acid is 1:0.02~0.4:2~6; S2: The reaction mixture is heated to obtain cone-shaped self-assembled copper microspheres; The heating reaction is carried out at a temperature of 80 ℃~90 ℃ for a time of 1~5 h. S3: Prepare an electrode slurry by mixing the self-assembled copper microspheres with the cone, acetylene black, 5 wt.% Nafion solution and anhydrous ethanol. Apply the electrode slurry to the electrode substrate at 60 ℃~80 ℃ to obtain the self-assembled copper microsphere electrode with the cone. The electrode substrate includes carbon paper, carbon cloth, graphite sheet, or titanium sheet.

2. The method for preparing a cone-shaped self-assembled copper microsphere electrode for uranium removal from water according to claim 1, characterized in that, The molar ratio of copper sulfate, tannic acid and ascorbic acid is 1:0.08~0.25:3~5.

3. The method for preparing a cone-shaped self-assembled copper microsphere electrode for uranium removal from water according to claim 1, characterized in that, In step S1, the pH of the aqueous solution system is adjusted to 8-10 using an alkaline solution, wherein the concentration of the alkaline solution is 0.5-1.0 mol / L. The alkaline solution is a sodium hydroxide solution and / or a potassium hydroxide solution.

4. The method for preparing a cone-shaped self-assembled copper microsphere electrode for uranium removal from water according to claim 1, characterized in that, The heating reaction process also includes stirring at a speed of 300~1000 r / min.

5. The method for preparing a cone-shaped self-assembled copper microsphere electrode for uranium removal from water according to claim 1, characterized in that, The mass-to-volume ratio of the self-assembled copper microspheres, acetylene black, 5 wt.% Nafion solution, and anhydrous ethanol in the cone is (1~2) mg:(0.1~0.3) mg:(1~5) μL:(10~30) μL.

6. A cone-shaped self-assembled copper microsphere prepared by the preparation method according to any one of claims 1 to 5.

7. A cone-shaped self-assembled copper microsphere electrode prepared by the preparation method according to any one of claims 1 to 5.

8. The application of a cone-shaped self-assembled copper microsphere electrode as described in claim 6 or as described in claim 7 in the electrochemical removal of uranium from water.

9. A method for electrochemical removal of uranium from water, characterized in that, Using the cone-shaped self-assembled copper microsphere electrode as described in claim 7 as the working electrode, an electrochemical treatment system was constructed. Electrochemical treatment was performed at a voltage of 0.2~1.0 V to remove UO2 from the water. 2+ Reduction and precipitation occur, achieving the removal, enrichment, and recovery of uranium in water; Alternatively, the cone-shaped self-assembled copper microspheres as described in claim 6 can be loaded onto an electrode substrate to obtain a cone-shaped self-assembled copper microsphere electrode. Using this cone-shaped self-assembled copper microsphere electrode as the working electrode, an electrochemical treatment system can be constructed. Electrochemical treatment can be performed at a voltage of 0.2~1.0 V to reduce UO2 in the water. 2+ Reduction and precipitation occur, achieving the removal, enrichment, and recovery of uranium in water; The water body includes tap water, groundwater, surface water, or seawater.

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