An iron monatomic phosphonic group electrode for removing uranium and a preparation method and application thereof

Abstract

This invention relates to the fields of water treatment and environmental treatment technology, and in particular to an iron single-atom phosphate group electrode for uranium removal, its preparation method, and its application. The preparation method includes: mixing an iron source, a support, and an active site modifier, grinding them to obtain a powder mixture; calcining the powder mixture under a protective atmosphere to obtain an iron single-atom catalyst; mixing the iron single-atom catalyst, water, and a phosphorus source, and performing a hydrothermal reaction to obtain a phosphate group-modified iron single-atom catalyst; coating the phosphate group-modified iron single-atom catalyst onto a carbon fiber substrate to obtain the uranium-removing iron single-atom phosphate group electrode; the support includes at least one of chitosan, silica, and sodium alginate. The iron single-atom phosphate group electrode prepared by this invention exhibits high selectivity for uranium, achieving a uranium removal efficiency of over 95% within 75 minutes, and maintaining over 90% removal efficiency after 8 cycles, while also having a wide operating pH range.

Description

Technical Field

[0001] This invention relates to the fields of water treatment and environmental treatment technology, and in particular to an iron single-atom phosphate group electrode for uranium removal, its preparation method, and its application. Background Technology

[0002] Uranium is a common radioactive metal widely found in nature and in some industrial activities, such as mining and nuclear energy production. Due to its long half-life and strong radioactivity, uranium causes long-term pollution to water bodies, soil, and the biological environment. Especially in nuclear wastewater discharge and mining wastewater treatment, uranium concentrations can far exceed environmental standards, seriously endangering ecosystems and human health. Traditional uranium removal technologies, including chemical precipitation, adsorption, and reverse osmosis, can reduce uranium concentration to some extent, but these methods often suffer from high processing costs, complex operations, and secondary pollution, making them unsuitable for large-scale, high-efficiency treatment.

[0003] In recent years, electrochemical removal technology has become an effective means of solving water pollution problems due to its advantages such as rapid reaction, simple operation, and low energy consumption. The selection of electrode materials is one of the key factors affecting the efficiency of electrochemical removal; excellent electrode materials can not only improve removal efficiency but also enhance the stability and durability of the catalyst. However, existing electrode materials exhibit poor selectivity for uranium in wastewater treatment, resulting in low uranium removal efficiency. Therefore, developing a highly efficient, stable, selective electrode with broad application prospects for the selective removal of uranium has significant scientific research value and practical application significance. Summary of the Invention

[0004] The purpose of this invention is to provide an iron single-atom phosphate group electrode for uranium removal, its preparation method and application, so as to solve the problems of low efficiency, poor stability and short service life of existing electrode materials in the uranium removal process.

[0005] To achieve the above objectives, the present invention provides a method for preparing an iron single-atom phosphate group electrode with uranium removed, comprising the following preparation steps:

[0006] S1. Mix the iron source, carrier, and active site regulator, and grind them to obtain a mixture powder;

[0007] S2. Under a protective atmosphere, the mixture powder is calcined to obtain an iron single-atom catalyst;

[0008] S3. Mix the iron single-atom catalyst, water, and phosphorus source, and perform a hydrothermal reaction to obtain an iron single-atom catalyst modified with phosphate groups.

[0009] S4. The iron single-atom catalyst modified with phosphate groups is coated on a carbon fiber substrate to obtain an iron single-atom phosphate group electrode for uranium removal.

[0010] The carrier in S1 includes at least one of chitosan, silica, and sodium alginate.

[0011] In this invention, the mass ratio of iron source, carrier, and active site regulator in S1 is 60-80 mg: 0.5-1 g: 6-8 g.

[0012] In this invention, the iron source in S1 includes at least one of ferric nitrate, ferric sulfate, and ferric chloride, preferably ferric nitrate, and the active site regulator includes at least one of potassium chloride, sodium chloride, and potassium sulfate, preferably potassium chloride.

[0013] In this invention, the grinding time in S1 is 5-8 hours.

[0014] In this invention, the protective atmosphere in S2 includes nitrogen or argon, the heating rate of calcination in S2 is 3-5℃ / min, the calcination temperature is 800-900℃, and the holding time of calcination is 2-2.5h.

[0015] In this invention, the mass-to-volume ratio of iron single-atom catalyst, water, and phosphorus source in S3 is 40-60 mg: 60-80 mL: 1.2-1.5 mL.

[0016] In this invention, the phosphorus source includes at least one of phytic acid, sodium phytate, and sodium phosphate, preferably phytic acid.

[0017] In this invention, after mixing in step S3, the mixture is sequentially stirred and sonicated before undergoing a hydrothermal reaction. The stirring time is 0.5-1 h, and the sonication time is 0.2-0.5 h.

[0018] In this invention, the temperature of the hydrothermal reaction in S3 is 95-100℃, and the time of the hydrothermal reaction is 12-15h.

[0019] In this invention, after the hydrothermal reaction in step S3 is completed, the hydrothermal reaction product is washed sequentially with ethanol and water, and then dried in a vacuum drying oven to obtain a phosphate-modified iron single-atom catalyst. The drying temperature is 45-60℃.

[0020] In this invention, the carbon fiber substrate material in S4 includes carbon cloth electrode, carbon felt electrode or carbon paper electrode, preferably carbon cloth electrode, and the thickness of the iron single-atom catalyst modified with phosphate group is 0.2-0.4 mm.

[0021] The present invention also provides an iron single-atom phosphate electrode with uranium removed, prepared by the above-described method for preparing an iron single-atom phosphate electrode with uranium removed.

[0022] This invention also provides the application of the aforementioned iron-monophosphate group electrode for uranium removal in wastewater uranium removal. The wastewater includes uranium-containing wastewater from mineral mining or nuclear energy production.

[0023] The present invention has the following beneficial effects:

[0024] This invention provides a method for preparing an iron single-atom phosphate group electrode for uranium removal, comprising the following preparation steps: S1, mixing an iron source, a support, and an active site modifier, and grinding them to obtain a mixture powder; S2, calcining the mixture powder under a protective atmosphere to obtain an iron single-atom catalyst; S3, mixing the iron single-atom catalyst, water, and a phosphorus source, and performing a hydrothermal reaction to obtain a phosphate group-modified iron single-atom catalyst; S4, coating the phosphate group-modified iron single-atom catalyst onto a carbon fiber substrate to obtain an iron single-atom phosphate group electrode for uranium removal; the support in S1 includes at least one of chitosan, silica, and sodium alginate.

[0025] This invention prepares an iron single-atom catalyst through grinding and calcination; a phosphorus source (phosphate group) is loaded onto the surface of the iron single-atom catalyst via a hydrothermal reaction, forming a composite structure with low charge transfer resistance and a large electrochemical active area, thereby improving the electrode's uranium removal efficiency. Simultaneously, the phosphate group (-PO4) is utilized... 3- ) and uranyl ions (UO2) 2+ The strong coordination ability between the phosphate group and uranyl ion enhances the selectivity for uranium. Furthermore, the coordination ability between the phosphate group and uranyl ion is less affected by pH, thus allowing the electrode to remove uranium under a relatively wide pH range.

[0026] The carrier selected in this invention includes at least one of chitosan, silica, and sodium alginate, which has a large specific surface area. Furthermore, the addition of an active site modifier (templating agent) during calcination forms a large number of porous structures on the carrier surface, further increasing the specific surface area and providing more active sites for iron source anchoring and subsequent loading of phosphorus source (phosphate groups) and adsorption of uranium. This also effectively reduces the migration and loss of the iron source during use, improving the stability and lifespan of the electrode.

[0027] The preparation method provided by this invention is simple and low-cost, applicable to water treatment equipment of different scales, and has broad application prospects.

[0028] The iron-containing single-atom phosphate electrode for uranium removal prepared by the method of this invention has an internal resistance of only 11.8-13.5 Ω, and can selectively remove uranium from wastewater, achieving a uranium removal efficiency of over 95% within a 75-minute treatment time. Furthermore, it maintains a high uranium removal efficiency at pH values ​​of 4-8, and after 8 cycles of use, the removal efficiency remains above 90%, demonstrating strong stability and pH adaptability. It can be widely applied to water treatment equipment of different scales, showing good market prospects and application potential.

[0029] 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

[0030] Figure 1 This is a graph showing the charge transfer internal resistance test results of the iron single-atom phosphate group electrodes with uranium removed prepared in Examples 1-3 of this invention;

[0031] Figure 2 The graph shows the charge transfer internal resistance test results of the iron single-atom electrode prepared in Comparative Example 1 and the carbon electrode prepared in Comparative Example 2 of this invention.

[0032] Figure 3 This is a graph showing the electrochemical active area test results of the iron single-atom phosphate group electrode with uranium removed prepared in Examples 1-3 of this invention;

[0033] Figure 4 The graph shows the electrochemical active area test results of the iron single-atom electrode prepared in Comparative Example 1 and the carbon electrode prepared in Comparative Example 2.

[0034] Figure 5 The graph shows the test results of the uranium removal efficiency of the iron single-atom phosphate group electrode prepared in Examples 1-3 of this invention.

[0035] Figure 6 The graph shows the test results of uranium removal efficiency of the iron single-atom electrode prepared in Comparative Example 1 and the carbon electrode prepared in Comparative Example 2 of this invention.

[0036] Figure 7 The graph shows the uranium removal efficiency test results of the iron single-atom phosphate group electrode for uranium removal prepared in Example 2 of this invention under different pH conditions (pH 4, 5, 6, 7, and 8);

[0037] Figure 8 This is a graph showing the uranium removal efficiency test results of the iron single-atom phosphate group electrode prepared in Example 2 of this invention after 8 cycles. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0039] Example 1

[0040] A method for preparing an iron single-atom phosphate group electrode with uranium removed includes the following preparation steps:

[0041] S1. Mix 60mg of ferric nitrate, 1g of chitosan, and 7g of potassium chloride, and grind them in an agate mortar for 5 hours to obtain a powdered mixture.

[0042] S2. Under a nitrogen atmosphere, the mixed powder was placed in a tube furnace and heated to 850°C at a heating rate of 3°C / min, and then held at that temperature for 2.5 hours for calcination to obtain an iron single-atom catalyst.

[0043] S3. Mix 60 mg of iron single-atom catalyst, 60 mL of water, and 1.5 mL of phytic acid. Stir for 1 h, then sonicate in an ultrasonicator for 0.2 h. Transfer to a polytetrafluoroethylene reactor and hydrothermally react at 100 °C for 12 h. Wash the hydrothermal reaction product with ethanol and water in sequence, then place it in a vacuum drying oven and dry at 50 °C to obtain the phosphate group modified iron single-atom catalyst.

[0044] S4. The iron single-atom catalyst modified with phosphate groups is coated on the surface of the carbon cloth electrode with a coating thickness of 0.2 mm to obtain the iron single-atom phosphate group electrode with uranium removal, denoted as FeNC / PO4-1.

[0045] Example 2

[0046] A method for preparing an iron single-atom phosphate group electrode with uranium removed includes the following preparation steps:

[0047] S1. Mix 80mg of ferric nitrate, 0.7g of chitosan, and 6g of potassium chloride, and grind them in an agate mortar for 6 hours to obtain a powdered mixture.

[0048] S2. Under a nitrogen atmosphere, the mixed powder was placed in a tube furnace and heated to 900°C at a heating rate of 4°C / min, and then held at that temperature for 2 hours for calcination to obtain an iron single-atom catalyst.

[0049] S3. Mix 40 mg of iron single-atom catalyst, 80 mL of water, and 1.2 mL of phytic acid, stir for 0.6 h, and then sonicate in an ultrasonicator for 0.5 h. Then transfer to a polytetrafluoroethylene reactor and hydrothermally react at 95 °C for 14 h. Wash the hydrothermal reaction product with ethanol and water in sequence, and then dry it in a vacuum drying oven at 45 °C to obtain the phosphate group modified iron single-atom catalyst.

[0050] S4. The iron single-atom catalyst modified with phosphate groups is coated on the surface of the carbon cloth electrode with a coating thickness of 0.3 mm to obtain the iron single-atom phosphate group electrode with uranium removal, denoted as FeNC / PO4-2.

[0051] Example 3

[0052] A method for preparing an iron single-atom phosphate group electrode with uranium removed includes the following preparation steps:

[0053] S1. Mix 70mg of ferric nitrate, 0.5g of chitosan, and 8g of potassium chloride, and grind them in an agate mortar for 8 hours to obtain a powdered mixture.

[0054] S2. Under a nitrogen atmosphere, the mixed powder was placed in a tube furnace and heated to 800°C at a heating rate of 5°C / min, and then held at that temperature for 2.2 hours for calcination to obtain an iron single-atom catalyst.

[0055] S3. Mix 50 mg of iron single-atom catalyst, 70 mL of water, and 1.3 mL of phytic acid. Stir for 0.5 h, then sonicate in an ultrasonicator for 0.4 h. Transfer to a polytetrafluoroethylene reactor and hydrothermally react at 98 °C for 15 h. Wash the hydrothermal reaction product with ethanol and water in sequence, then place it in a vacuum drying oven and dry at 60 °C to obtain the phosphate group modified iron single-atom catalyst.

[0056] S4. The iron single-atom catalyst modified with phosphate groups is coated on the surface of the carbon cloth electrode with a coating thickness of 0.4 mm to obtain the iron single-atom phosphate group electrode with uranium removal, denoted as FeNC / PO4-3.

[0057] Comparative Example 1

[0058] A method for preparing an iron single-atom electrode includes the following preparation steps:

[0059] S1. Mix 80mg of ferric nitrate, 0.7g of chitosan, and 6g of potassium chloride, and grind them in an agate mortar for 6 hours to obtain a powdered mixture.

[0060] S2. Under a nitrogen atmosphere, the mixed powder was placed in a tube furnace and heated to 900°C at a heating rate of 4°C / min, and then held at that temperature for 2 hours for calcination to obtain an iron single-atom catalyst.

[0061] S3. Coat the surface of the carbon cloth electrode with an iron single-atom catalyst to a thickness of 0.3 mm to obtain an iron single-atom electrode, denoted as FeNC.

[0062] Comparative Example 2

[0063] A method for preparing a carbon electrode includes the following preparation steps:

[0064] S1. Mix 0.7g of chitosan and 6g of potassium chloride, and grind them in an agate mortar for 6 hours to obtain a powdered mixture.

[0065] S2. Under a nitrogen atmosphere, the mixed powder is placed in a tube furnace and heated to 900°C at a heating rate of 4°C / min, then held at that temperature for 2 hours for calcination to obtain a carbon catalyst.

[0066] S3. Coat the carbon catalyst onto the surface of the carbon cloth electrode with a coating thickness of 0.3 mm to obtain the carbon electrode, denoted as the C electrode.

[0067] Performance testing:

[0068] The charge transfer resistance of the uranium-removed iron single-atom phosphate group electrodes prepared in Examples 1-3 was tested using an electrochemical workstation, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the charge transfer resistance of FeNC / PO4-1 prepared in Example 1 is 12.4Ω, the charge transfer resistance of FeNC / PO4-2 prepared in Example 2 is 11.8Ω, and the charge transfer resistance of FeNC / PO4-3 prepared in Example 3 is 13.5Ω.

[0069] The charge transfer resistance of the iron single-atom electrode prepared in Comparative Example 1 and the carbon electrode prepared in Comparative Example 2 were tested using an electrochemical workstation, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the charge transfer resistance of FeNC prepared in Comparative Example 1 is 25.6Ω, and the charge transfer resistance of C electrode (C) prepared in Comparative Example 2 is 48.5Ω.

[0070] The electrochemical active area of ​​the uranium-removed iron single-atom phosphate electrodes prepared in Examples 1-3 was tested using an electrochemical workstation, and the results are as follows: Figure 3 As shown. From Figure 3 It can be seen that the electrochemically active area of ​​FeNC / PO4-1 prepared in Example 1 is 115 cm². 2 The FeNC / PO4-2 prepared in Example 2 has an electrochemically active area of ​​125 cm². 2 The FeNC / PO4-3 prepared in Example 3 has an electrochemically active area of ​​111 cm². 2 .

[0071] The electrochemical active areas of the iron single-atom electrode prepared in Comparative Example 1 and the carbon electrode prepared in Comparative Example 2 were measured using an electrochemical workstation. The results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the electrochemically active area of ​​the FeNC prepared in Comparative Example 1 is 45.6 cm². 2 The electrochemically active area of ​​the C electrode (C) prepared in Comparative Example 2 was 12.3 cm². 2 .

[0072] Using the iron monophosphate electrode with uranium removed prepared in Examples 1-3 as the anode and the titanium sheet electrode as the cathode, respectively, the electrodes were placed in 100 mL of a mixed solution containing multiple coexisting ions (the mixed solution included: uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, wherein the concentrations of uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions were all 10 mg / L, and the pH of the mixed solution was 5.0). The experimental temperature was 25 °C, and the current density was 10 mA / cm². 2 Under these conditions, the uranium removal effect is as follows: Figure 5 As shown. From Figure 5 It can be seen that within 75 minutes, the FeNC / PO4-1 prepared in Example 1 achieved a uranium removal efficiency of 98.9%, the FeNC / PO4-2 prepared in Example 2 achieved a uranium removal efficiency of 99.8%, and the FeNC / PO4-3 prepared in Example 3 achieved a uranium removal efficiency of 95%. This confirms that the iron single-atom phosphate group electrode for uranium removal prepared by the method of the present invention has high selectivity and removal efficiency for uranium.

[0073] Using an iron single-atom electrode prepared in Comparative Example 1 and a carbon electrode prepared in Comparative Example 2 as anodes, and a titanium sheet electrode as cathode, respectively, they were placed in 100 mL of a mixed solution containing multiple coexisting ions (the mixed solution included: uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, wherein the concentrations of uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions were all 10 mg / L, and the pH of the mixed solution was 5.0). The experimental temperature was 25℃, and the current density was 10 mA / cm². 2 Under these conditions, the uranium removal effect is as follows: Figure 6 As shown. From Figure 6 It can be seen that the removal efficiency of FeNC prepared in Comparative Example 1 for uranium was 48.2% within 75 min, and the removal efficiency of C electrode (C) prepared in Comparative Example 2 for uranium was 29.3%, both of which were significantly lower than the iron single-atom phosphate group electrodes for uranium removal prepared in Examples 1-3 of this invention.

[0074] Using the uranium-removed iron monophosphate electrode prepared in Example 2 as the anode and a titanium sheet electrode as the cathode, the electrode was placed in 100 mL of a mixed solution containing multiple coexisting ions at different pH values ​​(pH 4, 5, 6, 7, and 8). The mixed solution contained uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, with each concentration of uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions being 10 mg / L. The experimental temperature was 25 °C, and the current density was 10 mA / cm². 2 Under these conditions, the uranium removal effect is as follows: Figure 7 As shown. From Figure 7 It can be seen that the FeNC / PO4-2 prepared in Example 2 has a uranium removal efficiency of 95.2%-99.8% over a wide pH range (4-8), which confirms that the iron single-atom phosphate group electrode for uranium removal prepared in this invention has a wide pH range and high efficiency in uranium removal.

[0075] Using the uranium-removed iron monophosphate electrode prepared in Example 2 as the anode and a titanium sheet electrode as the cathode, the electrode was placed in 100 mL of a mixed solution containing multiple coexisting ions (the mixed solution included: uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, wherein the concentrations of uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions were all 10 mg / L, and the pH of the mixed solution was 5.0) and a uranium solution (uranium concentration 10 mg / L, pH 5.0). The experiment was conducted at a temperature of 25 °C and a current density of 10 mA / cm². 2 Under the specified conditions, the uranium was degraded for 75 minutes, then the mixed solution was replaced (composition and pH remained unchanged), and the cycle was repeated 8 times. The efficiency of uranium removal was recorded each time, and the results are as follows: Figure 8 As shown. From Figure 8 It can be seen that the uranium removal efficiency reaches 97.7% by the 8th cycle, confirming that the uranium-removing iron single-atom phosphate group electrode prepared by the method of the present invention has excellent cycle stability and long service life.

[0076] 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 iron single-atom phosphate group electrode with uranium removed, characterized in that, The preparation steps include the following: S1. Mix the iron source, carrier, and active site regulator, and grind them to obtain a mixture powder; S2. Under a protective atmosphere, the mixture powder is calcined to obtain an iron single-atom catalyst; S3. Mix the iron single-atom catalyst, water, and phosphorus source, and perform a hydrothermal reaction to obtain an iron single-atom catalyst modified with phosphate groups. S4. The iron single-atom catalyst modified with phosphate groups is coated on a carbon fiber substrate to obtain an iron single-atom phosphate group electrode for uranium removal. The carrier in S1 includes at least one of chitosan, silica, and sodium alginate; The iron source in S1 includes at least one of ferric nitrate, ferric sulfate, and ferric chloride, and the active site modifier includes at least one of potassium chloride, sodium chloride, and potassium sulfate.

2. The method for preparing an iron single-atom phosphate group electrode for uranium removal according to claim 1, characterized in that, The mass ratio of iron source, carrier, and active site regulator in S1 is 60-80 mg: 0.5-1 g: 6-8 g.

3. The method for preparing an iron single-atom phosphate group electrode for removing uranium according to claim 1, characterized in that, The heating rate for calcination in S2 is 3-5℃ / min, the calcination temperature is 800-900℃, and the holding time for calcination is 2-2.5h.

4. The method for preparing an iron single-atom phosphate group electrode for uranium removal according to claim 1, characterized in that, The mass-to-volume ratio of iron single-atom catalyst, water, and phosphorus source in S3 is 40-60 mg: 60-80 mL: 1.2-1.5 mL.

5. The method for preparing an iron single-atom phosphate group electrode for uranium removal according to claim 1, characterized in that, The phosphorus source includes at least one of phytic acid, sodium phytate, and sodium phosphate.

6. The method for preparing an iron single-atom phosphate group electrode for removing uranium according to claim 1, characterized in that, The hydrothermal reaction temperature in S3 is 95-100℃, and the hydrothermal reaction time is 12-15h.

7. The method for preparing an iron single-atom phosphate group electrode for removing uranium according to claim 1, characterized in that, The carbon fiber substrate material in S4 includes carbon cloth electrode, carbon felt electrode or carbon paper electrode, and the coating thickness of the iron single-atom catalyst modified with phosphate groups is 0.2-0.4 mm.

8. The uranium-removed iron single-atom phosphate group electrode prepared by the method for preparing an iron single-atom phosphate group electrode according to any one of claims 1-7.

9. The application of the iron single-atom phosphate group electrode for uranium removal as described in claim 8 in the removal of uranium from wastewater.

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