Preparation method and application of graphite felt electrode material for electrochemical seawater uranium extraction

Abstract

The invention discloses a preparation method and application of an electrochemical seawater uranium extraction graphite felt electrode material, and belongs to the technical field of electrode materials. S2, preparing cyano diazonium salt; s3, taking the pretreated graphite felt as a substrate, taking cyanobenzene diazonium salt as a raw material, and growing the cyanobenzene diazonium salt on the graphite felt by adopting an electrochemical in-situ grafting method to obtain a p-cyanobenzene functional group loaded graphite felt; and S4, putting the graphite felt loaded with the cyanogen functional group into an alkaline alcohol solution of hydroxylamine hydrochloride, and carrying out a heating reaction to obtain the oximation functional group modified graphite felt electrode catalyst. According to the preparation method and the application of the electrochemical seawater uranium extraction graphite felt electrode material, the activity and the stability of an electrocatalyst are improved, and the preparation method and the application have important significance in promoting the commercialization process of a seawater electrocatalysis uranium extraction catalyst.

Description

Technical Field

[0001] This invention relates to the field of electrode materials technology, and in particular to a method for preparing and applying an electrochemical seawater uranium extraction graphite felt electrode material. Background Technology

[0002] Uranium is a key element in green nuclear energy. It primarily originates from terrestrial uranium mines, but reserves are limited. The ocean contains abundant dissolved uranium resources, but the concentration is extremely low. Processing seawater, with its low uranium concentration, high salinity, and complex ionic environment, is technically challenging. Therefore, research on the rapid and selective recovery of uranium from seawater is of great significance to the sustainable development of the nuclear industry.

[0003] Currently, common methods for extracting uranium from seawater include adsorption, membrane separation, photocatalytic reduction, and electrochemical reduction. Adsorption and membrane separation, as simple physical methods, have been widely studied, but their extraction efficiency is low and they are easily affected by various complex factors in seawater. Photocatalytic reduction, while offering advantages such as low cost and no pollution, has low efficiency and requires electrode material separation of the uranium-containing precipitate after electro-extraction. Electrochemical technology, due to its rapid adsorption rate, strong adsorption capacity, and excellent selectivity, shows great potential in cathode uranium extraction; for example, electrochemical methods can effectively enrich low-concentration uranium ions on the electrode surface during extraction, exhibiting high selectivity and excellent adsorption capacity. However, in complex multi-metal ion systems, these electrochemical extraction systems struggle to simultaneously possess low potential, high selectivity, and excellent extraction capacity. Furthermore, while electrochemical reduction is highly efficient in uranium extraction, similar to photocatalytic reduction, it also requires post-extraction processing. Furthermore, the electrochemical uranium extraction process at the cathode is typically coupled with an anodic oxidation reaction, specifically an oxygen evolution reaction with a theoretical potential of 1.23 V, thus forming a complete electrolytic cell. This electrolytic cell usually operates at a voltage exceeding 1.5 V, resulting in high energy consumption. Therefore, providing a high-efficiency, low-energy-consumption, and low-cost electrochemical seawater uranium extraction electrode material is crucial for achieving efficient seawater electrolytic uranium extraction. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying an electrochemical seawater uranium extraction graphite felt electrode material to solve the above-mentioned problems.

[0005] This invention provides a method for preparing an electrochemical seawater uranium extraction graphite felt electrode material, comprising the following steps: S1. Pretreatment of graphite felt; Preparation of S2 and cyanobenzene diazonium salt; S3. Using pretreated graphite felt as a substrate and cyanobenzene diazonium salt as a raw material, the cyanobenzene diazonium salt is grown on the graphite felt by electrochemical in-situ grafting method to obtain graphite felt loaded with cyanobenzene functional groups. S4. After heating the graphite felt loaded with cyano functional groups into an alkaline alcoholic solution of hydroxylamine hydrochloride, a graphite felt electrode material modified with oxime functional groups is obtained.

[0006] Preferably, in the above-mentioned method for preparing an electrochemical seawater uranium extraction graphite felt electrode material, the specific process of graphite felt pretreatment in step S1 is as follows: the graphite felt is soaked in an ethanol solution and ultrasonically treated for 3 minutes, then removed and washed with deionized water until neutral.

[0007] Preferably, in the above-mentioned method for preparing an electrochemical seawater uranium extraction graphite felt electrode material, the preparation method of cyanophenyl diazonium salt in step S2 is as follows: dissolve p-aminobenzonitrile in deionized water, add sodium nitrite and HBF4, stir at 5-15℃ for 1 hour, then wash the solid product with diethyl ether, rinse and filter with deionized water, and dry to obtain cyanophenyl diazonium salt.

[0008] Preferably, in the above-mentioned method for preparing an electrochemical seawater uranium extraction graphite felt electrode material, the electrochemical in-situ grafting method in step S3 specifically involves: mixing cyanobenzene diazonium salt and acetonitrile solution uniformly in a certain proportion as an electrolyte; fixing the graphite felt obtained in step S1 with an electrode clamp; Ag Using AgCl as the reference electrode and a platinum sheet electrode as the counter electrode, a voltage of 0 to -2V is applied to perform in-situ modification of the graphite felt.

[0009] Preferably, in the above-mentioned method for preparing an electrochemical seawater uranium extraction graphite felt electrode material, in step S4, the graphite felt loaded with cyano functional groups is placed in an alkaline alcohol solution of hydroxylamine hydrochloride and heated at 60-100°C for 24 hours to obtain a graphite felt electrode material modified with oxime functional groups.

[0010] This invention provides an application of the graphite felt electrode material obtained by the preparation method of the electrochemical seawater uranium extraction graphite felt electrode material as described above, wherein the graphite felt electrode material is applied to the seawater electrocatalytic uranium extraction reaction.

[0011] Specifically, the method involves using graphite felt electrode material as the working electrode and seawater as the electrolyte to carry out an electrocatalytic uranium extraction reaction.

[0012] Therefore, the preparation method and application of the electrochemical seawater uranium extraction graphite felt electrode material described above in this invention utilizes low-cost graphite felt as a substrate. The abundant pores in the graphite felt generate bubble flow, achieving self-cleaning and effectively suppressing product accumulation on the catalyst surface. It also exhibits good stability in seawater. By modifying the graphite felt with oxime functional groups, it can spontaneously capture uranyl ions during seawater electrolysis, achieving an enrichment effect. Modification on low-cost graphite felt effectively reduces the industrialization cost of the catalyst. Furthermore, a novel method for preparing an oxime-modified porous graphite felt electrode material is provided. Using graphite felt with abundant pores, excellent conductivity, and a large specific surface area as a substrate, oxime functional groups that can act as uranyl groups are modified to obtain a highly active and stable seawater electrolysis uranium extraction reaction electrode material.

[0013] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0014] Figure 1 These are SEM and EDS images of the electrochemical seawater uranium extraction graphite felt electrode material of Example 1 of the present invention, wherein (a) is the SEM image of pure graphite felt at 200µm, (b) is the SEM image of graphite felt with uranium products attached to the surface at 10µm, and (c) is the SEM image of graphite felt with uranium products attached to the surface at 30µm. Figure 2 This is the XRD pattern of the graphite felt with attached uranium products in Example 1 of the present invention; Figure 3 This is a comparison diagram of the uranium extraction effect of the modified graphite felt catalyst before and after applying a potential in Example 1 of the present invention; Figure 4 These are impedance diagrams of the graphite felt before and after modification in Embodiment 1 of the present invention. Detailed Implementation

[0015] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0016] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0017] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0018] Example 1 An electrochemical seawater uranium extraction graphite felt electrode material, the preparation method of which is as follows: (1) The size is 2 A 2cm graphite felt was immersed in an ethanol solution and sonicated for 3 minutes. After being removed, it was washed with deionized water until neutral, placed in a beaker, transferred to a forced-air drying oven, heated to 60℃, and kept at that temperature for 6 hours to obtain the pretreated graphite felt.

[0019] (2) Add 1.1g sodium nitrite to 5mL of deionized water until dissolved; add 1.7g p-aminobenzonitrile to 20mL of deionized water, stir at 5-15℃ for 10min, then add sodium nitrite solution to 6mL of HBF4 solution, continue stirring for 1h to obtain precipitate, wash repeatedly with ethanol and deionized water, and then dry to obtain p-cyanophenyl diazonium salt.

[0020] (3) Fix the graphite felt obtained in step (1) with an electrode clamp, Ag AgCl was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. A voltage of -0.6V was applied, and the electrode was immersed in an acetonitrile solution of 50mM p-cyanophenyl diazonium salt. After electrolysis for 5 seconds, the electrode was removed, washed with deionized water, and dried in an oven at 60℃ for 3 hours. After removal, 1.0g of hydroxylamine hydrochloride, 1.5g of triethylamine, and 20mL of ethanol were added to the reaction flask. The reaction was heated at 85℃ for 24 hours. The electrode was then washed with deionized water until neutral and dried to obtain the oxime-modified graphite felt electrode material.

[0021] Example 2 A carbon-based porous uranium extraction electrode material is prepared by the following method: (1) The size is 2 A 2cm graphite felt was immersed in an ethanol solution and sonicated for 3 minutes. After being removed, it was washed with deionized water until neutral, placed in a beaker, transferred to a forced-air drying oven, heated to 60℃, and kept at that temperature for 6 hours to obtain the pretreated graphite felt.

[0022] (2) Add 1.5g sodium nitrite to 5mL of deionized water until dissolved; add 2.5g p-aminobenzonitrile to 20mL of deionized water, stir at 5-15℃ for 10min, then add sodium nitrite solution to 6mL of HBF4 solution, continue stirring for 1.5h to obtain precipitate, wash repeatedly with ethanol and deionized water, and then dry to obtain p-cyanophenyl diazonium salt.

[0023] (3) Fix the graphite felt obtained in step (1) with an electrode clamp, Ag AgCl was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. A voltage of -0.2V was applied, and the electrode was immersed in an acetonitrile solution of 100mM p-cyanophenyl diazonium salt. After electrolysis for 20 seconds, the electrode was removed, washed with deionized water, and dried in an oven at 70℃ for 3 hours. After removal, 1.5g of hydroxylamine hydrochloride, 2.5g of triethylamine, and 30 mL of ethanol were added to the reaction flask. The reaction was heated at 100℃ for 12 hours. The electrode was then washed with deionized water until neutral and dried to obtain the oxime-modified graphite felt electrode material.

[0024] Example 3 An electrochemical seawater uranium extraction graphite felt electrode material, the preparation method of which is as follows: (1) The size is 2 A 2cm graphite felt was immersed in an ethanol solution and sonicated for 3 minutes. After being removed, it was washed with deionized water until neutral, placed in a beaker, transferred to a forced-air drying oven, heated to 60℃, and kept at that temperature for 6 hours to obtain the pretreated graphite felt.

[0025] (2) Add 1.5g sodium nitrite to 10mL of deionized water until dissolved; add 2.5g p-aminobenzonitrile to 20mL of deionized water, stir at 10-25℃ for 5min, then add sodium nitrite solution to 5mL of HBF4 solution, continue stirring for 2h to obtain precipitate, wash repeatedly with ethanol and deionized water, and then dry to obtain p-cyanophenyl diazonium salt.

[0026] (3) Fix the graphite felt obtained in step (1) with an electrode clamp, Ag AgCl was used as the reference electrode, and a platinum sheet electrode was used as the counter electrode. A voltage of -1.0V was applied, and the electrode was immersed in an acetonitrile solution of 10mM p-cyanophenyl diazonium salt. After electrolysis for 30 seconds, the electrode was removed, washed with deionized water, and dried in an oven at 60℃ for 3 hours. After removal, 1.0g of hydroxylamine hydrochloride, 2.0g of triethylamine, and 20 mL of ethanol were added to the reaction flask. The reaction was heated at 110℃ for 12 hours. The electrode was then washed with deionized water until neutral and dried to obtain the oxime-modified graphite felt electrode material.

[0027] Experimental testing: The structures of the graphite felt electrode materials prepared in Example 1 before and after oxime modification were characterized, and the results are as follows. Figure 1-2 As shown, the electrochemical performance was tested, and the results are as follows. Figure 3-4 As shown.

[0028] Structural morphology and elemental characterization of graphite felt catalysts before and after oxime modification: Depend on Figure 1 As shown in (a)-(c), the morphology of the graphite felt electrode material before and after oxime modification can be observed using scanning electron microscopy (SEM). Figure 1 As shown in (a), the surface of unmodified graphite felt material is smooth. Figure 1 As shown in (b), the uranium solid extracted by electrocatalysis partially adheres to the surface of the electrode material. Figure 1 As shown in (c), the elemental distribution information was characterized by EDS attached to the scanning electron microscope. The uniform distribution of each element in the microscopic region of the uranium product sample indicates that the extracted uranium product was successfully generated.

[0029] Depend on Figure 2 It can be seen that when X-ray diffraction (XRD) is used to characterize the elemental composition of the solid product after electrocatalytic uranium extraction from the electrode material, the yellow product attached to the electrode surface shows obvious XRD diffraction peak information of Na2O(UO3·H2O)x.

[0030] Cathode uranium extraction performance test: An IT test was conducted using a two-electrode system, a single-cell electrolyzer, in natural seawater at a voltage of -1.5V. Figure 3 As can be seen, the graphite felt electrode material prepared in Example 1 exhibits excellent uranium extraction performance. Under applied voltage, the removal rate reaches 93% after 13 hours of reaction. In contrast, the removal efficiency of uranium ions in simple adsorption tests is only about 20%. The electrolyte is natural seawater with added uranyl nitrate hexahydrate, prepared to a uranium concentration of 50 ppm.

[0031] Impedance tests were performed on the graphite felt before and after modification using a three-electrode system and a single-cell electrolytic cell. Figure 4 It can be seen that the impedance of the graphite felt electrode material prepared in Example 1 increases after functional group modification, which indicates that the modified functional groups occupy some of the active sites on the graphite felt, which is beneficial to improving the efficiency of uranium extraction.

[0032] The uranium extraction performance test results of Examples 2 and 3 are basically consistent with those of Example 1.

[0033] Therefore, this invention employs the above-mentioned preparation method and application of an electrochemical seawater uranium extraction graphite felt electrode material. Using graphite felt with abundant pores, excellent conductivity, and large specific surface area as a substrate, it is modified with oxime functional groups that can act as uranyl groups to obtain a highly active and stable electrocatalyst for seawater electrolysis uranium extraction. The abundant pores in the graphite felt generate bubble flow, achieving self-cleaning of the electrocatalyst and reducing product accumulation on the surface of the electrocatalyst.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an electrochemical uranium extraction seawater graphite felt electrode material, characterized in that, The method comprises the following steps: S1, pretreatment of the graphite felt; S2, preparation of the diazonium salt of cyanobenzene; S3, using the pretreated graphite felt as a substrate and the diazonium salt of cyanobenzene as raw material, growing on the graphite felt by an electrochemical in-situ grafting method to obtain the graphite felt loaded with cyanobenzene functional groups; S4, placing the graphite felt loaded with cyanobenzene functional groups into an alkaline alcohol solution of hydroxylamine hydrochloride for heating reaction to obtain the graphite felt electrode material modified with oxime functional groups.

2. The preparation method of the electrochemical seawater uranium extraction graphite felt electrode material according to claim 1, characterized in that, The specific process of the graphite felt pretreatment in the step S1 is as follows: the graphite felt is soaked in an ethanol solution and taken out after ultrasonic treatment for 3 min, and then washed with deionized water until neutral.

3. The method for preparing an electrochemical seawater uranium extraction graphite felt electrode material according to claim 1, characterized in that, The preparation method of the diazonium salt of cyanobenzene in the step S2 is as follows: p-aminobenzonitrile is dissolved in deionized water, sodium nitrite and HBF4 are added, and stirred at 5-15℃ for 1 h, then the solid product is washed with diethyl ether, washed with deionized water, filtered and dried to obtain the diazonium salt of cyanobenzene.

4. The method for preparing an electrochemical seawater uranium extraction graphite felt electrode material according to claim 1, characterized in that, The electrochemical in-situ grafting method in step S3 is as follows: mixing cyano benzene diazonium salt and acetonitrile solution in proportion to make them uniform as an electrolyte, fixing the graphite felt obtained in step S1 with an electrode clamp, and applying a voltage of 0 to -2V to the graphite felt to modify it in-situ. AgCl is used as a reference electrode, a platinum sheet electrode is used as a counter electrode, a voltage of 0 to -2V is applied, and the graphite felt is modified in-situ.

5. The method for preparing an electrochemical seawater uranium extraction graphite felt electrode material according to claim 1, characterized in that, In the step S4, the graphite felt loaded with cyanobenzene functional groups is placed into an alkaline alcohol solution of hydroxylamine hydrochloride for heating reaction at 60-100℃ for 24 h to obtain the graphite felt electrode material modified with oxime functional groups.

6. The use of the graphite felt electrode material obtained by the method for preparing the electrochemical uranium extraction from seawater graphite felt electrode material according to any one of claims 1 to 5, characterized in that, The graphite felt electrode material is applied to the electrocatalytic uranium extraction reaction of seawater.

7. Use of a graphite felt electrode material according to claim 6, characterized in that The graphite felt electrode material is used as a working electrode, and the seawater is used as an electrolyte to perform the electrocatalytic uranium extraction reaction.

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