Iron monatomic phosphate group electrode for removing uranium as well as preparation method and application of iron monatomic phosphate group electrode

Abstract

The invention relates to the technical field of water treatment and environment treatment, in particular to an iron monatomic phosphate group electrode for removing uranium and a preparation method and application thereof.The preparation method comprises the steps that an iron source, a carrier and an active site regulator are mixed and ground, and mixture powder is obtained; under a protective atmosphere, calcining the mixture powder to obtain an iron monatomic catalyst; the method comprises the following steps: mixing an iron monatomic catalyst, water and a phosphorus source, and carrying out hydrothermal reaction to obtain a phosphate group modified iron monatomic catalyst; coating the phosphate group modified iron monatomic catalyst in a carbon fiber substrate material to obtain the uranium-removed iron monatomic phosphate group electrode; the carrier comprises at least one of chitosan, silicon dioxide and sodium alginate. The prepared iron monatomic phosphate group electrode is high in uranium selectivity, the uranium removal efficiency reaches 95% or above within 75 min, the removal efficiency is still kept 90% or above after 8 cycle periods, and the iron monatomic phosphate group electrode has a wide pH application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment and environmental treatment, in particular to an iron monatomic phosphate group electrode for removing uranium and a preparation method and application thereof. BACKGROUND

[0002] Uranium is a common radioactive metal that exists widely in nature and some industrial activities, such as mineral exploitation and nuclear energy production. Due to its long half-life and strong radioactivity, the presence of uranium causes long-term pollution to water bodies, soil and biological environment. Especially in the discharge of nuclear wastewater and the treatment of mine wastewater, the concentration of uranium may be much higher than the environmental standard, which seriously endangers the ecological system and human health. Traditional uranium removal technologies, including chemical precipitation, adsorption and reverse osmosis, can reduce the concentration of uranium to some extent, but these methods often have problems such as high treatment cost, complex operation and secondary pollution, which are difficult to meet the demand of large-scale and efficient treatment.

[0003] In recent years, electrochemical removal technology has become an effective means to solve water pollution problems due to its rapid reaction, simple operation and low energy consumption. The selection of electrode material is one of the key factors affecting the efficiency of electrochemical removal. An excellent electrode material not only can improve the removal efficiency, but also can improve the stability and durability of the catalyst. However, the existing electrode materials have poor selectivity for uranium in wastewater treatment, which leads to low removal efficiency of uranium. Therefore, it is of great scientific research value and practical application significance to develop an electrode that can selectively remove uranium with high efficiency, stability and selectivity and has wide application prospect. SUMMARY

[0004] The purpose of the present application is to provide an iron monatomic phosphate group electrode for removing uranium and a preparation method and application thereof, in order to solve the problems of low efficiency, poor stability and short service life of existing electrode materials in the process of removing uranium.

[0005] To achieve the above-mentioned purpose, the present application provides a preparation method of an iron monatomic phosphate group electrode for removing uranium, which comprises the following preparation steps: S1, mixing an iron source, a carrier and an active site regulator, grinding to obtain a mixture powder; S2, calcining the mixture powder under a protective atmosphere to obtain an iron monatomic catalyst; S3, mixing the iron monatomic catalyst, water and a phosphorus source, and hydrothermal reaction to obtain a phosphoric acid group modified iron monatomic catalyst; S4, coating the phosphoric acid group modified iron monatomic catalyst on a carbon fiber base material to obtain an iron monatomic phosphate group electrode for removing uranium; The carrier in S1 includes at least one of chitosan, silicon dioxide and sodium alginate.

[0006] In the present application, the mass ratio of the iron source, the carrier and the active site regulator in S1 is 60-80 mg: 0.5-1 g: 6-8 g.

[0007] In the present application, the iron source in S1 includes at least one of ferric nitrate, ferric sulfate and ferric chloride, and preferably ferric nitrate; and the active site regulator includes at least one of potassium chloride, sodium chloride and potassium sulfate, and preferably potassium chloride.

[0008] In the present application, the grinding time in S1 is 5-8 h.

[0009] In the present application, the protective atmosphere in S2 includes nitrogen or argon, the temperature rising rate of the calcination in S2 is 3-5℃ / min, the calcination temperature is 800-900℃, and the holding time of the calcination is 2-2.5 h.

[0010] In the present application, the mass-volume ratio of the iron single-atom catalyst, water and the phosphorus source in S3 is 40-60 mg: 60-80 mL: 1.2-1.5 mL.

[0011] In the present application, the phosphorus source includes at least one of phytic acid, sodium phytate and sodium phosphate, and preferably phytic acid.

[0012] In the present application, after mixing in S3, the mixture is sequentially subjected to stirring and ultrasonic treatment and then subjected to hydrothermal reaction. The stirring time is 0.5-1 h, and the ultrasonic treatment time is 0.2-0.5 h.

[0013] In the present application, the hydrothermal reaction temperature in S3 is 95-100℃, and the hydrothermal reaction time is 12-15 h.

[0014] In the present application, after the hydrothermal reaction in S3 is completed, the hydrothermal reaction product is sequentially washed with ethanol and water and then dried in a vacuum drying box to obtain the phosphoric group modified iron single-atom catalyst. The drying temperature is 45-60℃.

[0015] In the present application, the carbon fiber base material in S4 includes a carbon cloth electrode, a carbon felt electrode or a carbon paper electrode, and preferably a carbon cloth electrode. The phosphoric group modified iron single-atom catalyst is coated to a thickness of 0.2-0.4 mm.

[0016] The present application also provides a uranium-removing iron single-atom phosphoric group electrode prepared by the preparation method of the uranium-removing iron single-atom phosphoric group electrode.

[0017] The present application also provides the application of the uranium-removing iron single-atom phosphoric group electrode in wastewater uranium removal. The wastewater includes uranium-containing wastewater generated in mineral exploitation or uranium-containing wastewater generated in nuclear energy production.

[0018] The present invention has the following beneficial effects: 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a charge transfer resistance test result graph of the uranium-removed iron monatomic phosphoric group electrode prepared in the present application embodiment 1-3; Figure 2 is a charge transfer resistance test result graph of the iron monatomic electrode prepared in the present application comparative example 1, and the carbon electrode prepared in the present application comparative example 2; Figure 3 is an electrochemical active area test result graph of the uranium-removed iron monatomic phosphoric group electrode prepared in the present application embodiment 1-3; Figure 4 is an electrochemical active area test result graph of the iron monatomic electrode prepared in the present application comparative example 1, and the carbon electrode prepared in the present application comparative example 2; Figure 5 is a uranium removal efficiency test result graph of the uranium-removed iron monatomic phosphoric group electrode prepared in the present application embodiment 1-3; Figure 6 is a uranium removal efficiency test result graph of the iron monatomic electrode prepared in the present application comparative example 1, and the carbon electrode prepared in the present application comparative example 2; Figure 7 is a uranium removal efficiency test result graph of the uranium-removed iron monatomic phosphoric group electrode prepared in the present application embodiment 2 under different pH (pH is 4, 5, 6, 7, 8 respectively) conditions; Figure 8 is a uranium removal efficiency test result graph of the uranium-removed iron monatomic phosphoric group electrode prepared in the present application embodiment 2 after 8 cycles. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with the drawings and embodiments. Unless otherwise defined, the technical terms or scientific terms used in the present application shall be the commonly understood meanings by those skilled in the art. The features mentioned in the present application or the features mentioned in the specific examples can be combined arbitrarily, and these specific examples are only used to illustrate the present application and not to limit the scope of the present application.

[0026] Embodiment 1 A preparation method of a uranium-removed iron monatomic phosphoric group electrode, comprising the following preparation steps: S1, mix 60 mg of ferric nitrate, 1 g of chitosan, and 7 g of potassium chloride, grind in a agate mortar for 5 h to obtain a mixture powder; S2, under a nitrogen atmosphere, place the mixture powder in a tube furnace, heat to 850℃ at a heating rate of 3℃ / min, and then keep the temperature for 2.5 h to perform calcination, to obtain an iron monatomic catalyst; S3, mix the iron monatomic catalyst 60 mg, water 60 mL and phytic acid 1.5 mL, stir for 1 h, then place in an ultrasonic device and ultrasonic for 0.2 h, then transfer to a polytetrafluoroethylene reaction kettle, and hydrothermally react at 100 DEG C for 12 h, then wash the hydrothermal reaction product with ethanol and water in sequence, and place in a vacuum drying box and dry at 50 DEG C to obtain the phosphoric group modified iron monatomic catalyst; S4, coat the phosphoric group modified iron monatomic catalyst on the surface of a carbon cloth electrode with a coating thickness of 0.2 mm to obtain a uranium removal iron monatomic phosphoric group electrode, denoted as FeNC / PO4-1.

[0027] Example 2 A preparation method of a uranium removal iron monatomic phosphoric group electrode, comprising the following preparation steps: S1, mix iron nitrate 80 mg, chitosan 0.7 g and potassium chloride 6 g, grind in a agate mortar for 6 h to obtain a mixture powder; S2, under a nitrogen atmosphere, heat the mixture powder to 900 DEG C at a temperature increasing rate of 4 DEG C / min, and then keep the temperature for 2 h to perform calcination, to obtain an iron monatomic catalyst; S3, mix the iron monatomic catalyst 40 mg, water 80 mL and phytic acid 1.2 mL, stir for 0.6 h, then place in an ultrasonic device and ultrasonic for 0.5 h, then transfer to a polytetrafluoroethylene reaction kettle, and hydrothermally react at 95 DEG C for 14 h, then wash the hydrothermal reaction product with ethanol and water in sequence, and place in a vacuum drying box and dry at 45 DEG C to obtain the phosphoric group modified iron monatomic catalyst; S4, coat the phosphoric group modified iron monatomic catalyst on the surface of a carbon cloth electrode with a coating thickness of 0.3 mm to obtain a uranium removal iron monatomic phosphoric group electrode, denoted as FeNC / PO4-2.

[0028] Example 3 A preparation method of a uranium removal iron monatomic phosphoric group electrode, comprising the following preparation steps: S1, mix iron nitrate 70 mg, chitosan 0.5 g and potassium chloride 8 g, grind in a agate mortar for 8 h to obtain a mixture powder; S2, under a nitrogen atmosphere, heat the mixture powder to 800 DEG C at a temperature increasing rate of 5 DEG C / min, and then keep the temperature for 2.2 h to perform calcination, to obtain an iron monatomic catalyst; S3, mix the iron monatomic catalyst 50 mg, water 70 mL and phytic acid 1.3 mL, stir for 0.5 h, then ultrasonic in an ultrasonic device for 0.4 h, then transfer to a polytetrafluoroethylene reaction kettle, and hydrothermally react at 98 ℃ for 15 h, then wash the hydrothermal reaction product with ethanol and water in sequence, and dry in a vacuum drying box at 60 ℃ to obtain the phosphoric group modified iron monatomic catalyst; S4, coat the phosphoric group modified iron monatomic catalyst on the surface of a carbon cloth electrode with a coating thickness of 0.4 mm to obtain a uranium-removed iron monatomic phosphoric group electrode, denoted as FeNC / PO4-3.

[0029] Comparative Example 1 A method for preparing an iron monatomic electrode, comprising the following preparation steps: S1, mix ferric nitrate 80 mg, chitosan 0.7 g and potassium chloride 6 g, grind in a agate mortar for 6 h to obtain a mixture powder; S2, place the mixture powder in a tube furnace under a nitrogen atmosphere, heat to 900 ℃ at a heating rate of 4 ℃ / min, and then heat for 2 h to calcine, to obtain an iron monatomic catalyst; S3, coat the iron monatomic catalyst on the surface of a carbon cloth electrode with a coating thickness of 0.3 mm to obtain an iron monatomic electrode, denoted as FeNC.

[0030] Comparative Example 2 A method for preparing a carbon electrode, comprising the following preparation steps: S1, mix chitosan 0.7 g and potassium chloride 6 g, grind in a agate mortar for 6 h to obtain a mixture powder; S2, place the mixture powder in a tube furnace under a nitrogen atmosphere, heat to 900 ℃ at a heating rate of 4 ℃ / min, and then heat for 2 h to calcine, to obtain a carbon catalyst; S3, coat the carbon catalyst on the surface of a carbon cloth electrode with a coating thickness of 0.3 mm to obtain a carbon electrode, denoted as C electrode.

[0031] Performance test: The charge transfer resistance of the uranium-removed iron monatomic phosphoric group electrode prepared in Examples 1-3 was tested by an electrochemical workstation, and the results are shown in Figure 1 From Figure 1 It can be seen that the charge transfer resistance of FeNC / PO4-1 prepared in Example 1 is 12.4 Ω, the charge transfer resistance of FeNC / PO4-2 prepared in Example 2 is 11.8 Ω, and the charge transfer resistance of FeNC / PO4-3 prepared in Example 3 is 13.5 Ω.

[0032] 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.

[0033] 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 .

[0034] 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 .

[0035] 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.

[0036] The iron monatomic electrode prepared in Comparative Example 1 and the carbon electrode prepared in Comparative Example 2 were used as an anode, and a titanium sheet electrode was used as a cathode, and then the electrodes were placed in 100 mL of a mixed solution containing multiple coexisting ions (the mixed solution contained uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, and the concentrations of the 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). Under the conditions of an experimental temperature of 25°C and a current density of 10 mA / cm 2 , the uranium removal effect was as shown in Figure 6 . It can be seen from Figure 6 that the uranium removal efficiency of the FeNC prepared in Comparative Example 1 was 48.2% within 75 min, and the uranium removal efficiency of the C electrode (C) prepared in Comparative Example 2 was 29.3%, both of which were significantly lower than the uranium removal efficiency of the iron monatomic phosphate group electrode prepared in Examples 1-3.

[0037] The uranium removal iron monatomic phosphate group electrode prepared in Example 2 was used as an anode, and a titanium sheet electrode was used as a cathode, and then the electrodes were placed in 100 mL of a mixed solution containing multiple coexisting ions at different pH values (pH values were 4, 5, 6, 7, and 8, respectively) (the mixed solution contained uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, and the concentrations of the uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions were all 10 mg / L). Under the conditions of an experimental temperature of 25°C and a current density of 10 mA / cm 2 , the uranium removal effect was as shown in Figure 7 . It can be seen from Figure 7 that the uranium removal efficiency of the FeNC / PO4-2 prepared in Example 2 was 95.2%-99.8% within a relatively wide pH range (4-8), which confirmed that the uranium removal iron monatomic phosphate group electrode prepared in the application had a relatively wide pH use range and a high uranium removal efficiency.

[0038] The uranium removal iron monatomic phosphate group electrode prepared in Example 2 was used as an anode, and a titanium sheet electrode was used as a cathode, and then the electrodes were placed in 100 mL of a mixed solution containing multiple coexisting ions (the mixed solution contained uranium ions, chloride ions, nitrate ions, bicarbonate ions, sodium ions, potassium ions, and magnesium ions, and the concentrations of the 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 uranium concentration was 10 mg / L, and the pH was 5.0). Under the conditions of an experimental temperature of 25°C and a current density of 10 mA / cm 2The solution was replaced with fresh solution (same composition and pH) and the cycle was repeated 8 times. The efficiency of uranium removal was recorded each time and the results are shown in Table 1. Figure 8 As can be seen from Table 1, the efficiency of uranium removal was as high as 97.7% after 8 cycles, which demonstrates that the uranium-removing iron monatomic phosphonic group electrode prepared by the preparation method of the present application has excellent cycle stability and long service life. Figure 8

[0039] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.​

Claims

1. A method for preparing an iron monatomic phosphonate group electrode for removing uranium, characterized by, The preparation method comprises the following steps: S1, mixing, grinding the iron source, carrier and active site regulator to obtain a mixture powder; S2, calcining the mixture powder under a protective atmosphere to obtain an iron monatomic catalyst; S3, mixing the iron monatomic catalyst, water and phosphorus source, and hydrothermally reacting to obtain a phosphoric group modified iron monatomic catalyst; S4, coating the phosphoric group modified iron monatomic catalyst on a carbon fiber base material to obtain a uranium removal iron monatomic phosphoric group electrode; The carrier in S1 comprises at least one of chitosan, silicon dioxide and sodium alginate.

2. The method of claim 1, wherein the method is characterized by: The mass ratio of the iron source, carrier and active site regulator in S1 is 60-80 mg: 0.5-1 g: 6-8 g.

3. The method of claim 1, wherein the method is characterized by: The iron source in S1 comprises at least one of ferric nitrate, ferric sulfate and ferric chloride, and the active site regulator comprises at least one of potassium chloride, sodium chloride and potassium sulfate.

4. The method of claim 1, wherein the method is characterized by: The temperature rising rate of the calcination in S2 is 3-5 ℃ / min, the temperature of the calcination is 800-900 ℃, and the holding time of the calcination is 2-2.5 h.

5. The method of claim 1, wherein the method is characterized by: The mass-volume ratio of the iron monatomic catalyst, water and phosphorus source in S3 is 40-60 mg: 60-80 mL: 1.2-1.5 mL.

6. The method of claim 1, wherein the method is characterized by: The phosphorus source comprises at least one of phytic acid, sodium phytate and sodium phosphate.

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

8. The method for preparing an iron single-atom phosphate group electrode for removing uranium according to claim 1, characterized in that, The carbon fiber base material in S4 comprises a carbon cloth electrode, a carbon felt electrode or a carbon paper electrode, and the thickness of the phosphoric group modified iron monatomic catalyst is 0.2-0.4 mm.

9. A uranium removal iron monatomic phosphoric group electrode prepared by the preparation method of the uranium removal iron monatomic phosphoric group electrode according to any one of claims 1-8.

10. The uranium removal iron monatomic phosphoric group electrode according to claim 9 is applied to wastewater uranium removal.

Images