Fe3o4-cnt / mgo-atp / sa electrode material and application thereof

Abstract

The application relates to the technical field of soil remediation, in particular to a Fe3O4-CNT / MgO-ATP / SA electrode material and application thereof. The conventional auxiliary electrode used in the electrokinetic remediation technology has poor mechanical performance and poor removal effect on heavy metal ions in the soil. In view of the above problems, the application provides a Fe3O4-CNT / MgO-ATP / SA electrode material, which is obtained by encapsulating modified MgO attapulgite rod soil and Fe3O4 magnetized carbon nanotubes in a crosslinked network structure formed by sodium alginate to obtain an auxiliary electrode material. The obtained auxiliary electrode material has good conductivity, environmental protection and corrosion resistance. The MgO-ATP in the auxiliary electrode material has good adsorption capacity for heavy metal ions. The Fe3O4-CNT endows the auxiliary electrode material with excellent conductivity. The crosslinked network structure of the auxiliary electrode material has good mechanical strength and stability.

Description

Technical Field

[0001] This invention relates to the field of soil remediation technology, specifically to a Fe3O4-CNT / MgO-ATP / SA electrode material and its application. Background Technology

[0002] With rapid industrialization, soil pollution has become increasingly serious, especially heavy metal pollution, which poses a significant threat to the environment and human health. While traditional physical, chemical, and biological remediation technologies have alleviated soil pollution to some extent, they suffer from low remediation efficiency, high costs, and a tendency to cause secondary pollution. In recent years, electrokinetic remediation technology has attracted widespread attention due to its ability to effectively remove heavy metal ions from soil. However, the performance of the auxiliary electrode significantly impacts remediation efficiency during the electrokinetic remediation process. Existing electrode materials generally suffer from poor conductivity, insufficient stability, and susceptibility to corrosion, making it difficult to meet the demands for long-term, efficient, and low-cost remediation. Therefore, developing an auxiliary electrode material with high conductivity, excellent adsorption properties, strong corrosion resistance, and environmental friendliness has become an urgent problem to be solved in the field of soil pollution remediation.

[0003] Most current auxiliary electrodes, such as the Chinese invention patent CN 114029332 A which discloses an apparatus and method for electro-remediation of cadmium-contaminated soil using an activated graphene auxiliary electrode, have the following drawbacks: the combination of activated graphene and filter paper may be subject to mechanical wear or structural damage during long-term use, which may affect the durability and efficiency of the remediation effect and cause secondary pollution to water bodies and soil. Summary of the Invention

[0004] A problem with existing technologies is that conventional auxiliary electrodes used in electroremediation technologies have poor mechanical properties, making it difficult to achieve a 70% removal rate of heavy metal ions from soil. To address these issues, this invention provides a Fe3O4-CNT / MgO-ATP / SA electrode material, the preparation method of which includes the following steps:

[0005] (1) ATP powder and soluble magnesium salt undergo a hydrothermal reaction under alkaline conditions. The reaction liquid is separated into solid and liquid to obtain a solid product. The obtained solid product is placed at high temperature and calcined in air to obtain MgO-ATP loaded with magnesium oxide particles.

[0006] (2) Acidified carbon nanotubes with Fe 2+ Fe 3+ The soluble salts and surfactants were mixed evenly in an aqueous solution, the pH of the solution was adjusted to be alkaline, and the reaction was stirred until the iron oxides were adsorbed on the walls of the acidified carbon nanotubes. The solid products in the solution were collected by magnetic attraction to obtain Fe3O4-CNT.

[0007] (3) Mix and disperse MgO-ATP and Fe3O4-CNT in deionized water to obtain Fe3O4-CNT / MgO-ATP suspension;

[0008] (4) SA aqueous solution was added dropwise to Fe3O4-CNT / MgO-ATP suspension while stirring. After the reaction was completed, the reaction solution was filtered. The obtained filter cake was freeze-dried and then heat-treated at high temperature under nitrogen atmosphere to obtain the final product.

[0009] Preferably, the temperature of the hydrothermal reaction in step (1) is not lower than 120°C and the hydrothermal time is not less than 6 hours.

[0010] Preferably, the high-temperature calcination temperature in step (1) is not higher than 500°C and the calcination time is not less than 2 hours.

[0011] Preferably, in step (2), the acidified carbon nanotubes are obtained by adding carbon nanotubes to a dilute nitric acid aqueous solution for oxidation.

[0012] Preferably, the surfactant is SDS.

[0013] Preferably, the mass ratio of MgO-ATP to Fe3O4-CNT in step (3) is 0.1-2:1.

[0014] Preferably, in step (3), the mass ratio of MgO-ATP to Fe3O4-CNT is 1:1.

[0015] Preferably, the mass ratio of SA in step (4) to MgO-ATP and Fe3O4-CNT in step (3) is 1:1:1.

[0016] Preferably, the temperature of the high-temperature heat treatment in step (4) is not higher than 450°C and the heat treatment time is not less than 2 hours.

[0017] Preferably, the freeze-drying time in step (4) is not less than 24 hours.

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

[0019] (1) In this invention, magnesium oxide modified attapulgite (MgO-ATP) and magnetized carbon nanotubes (Fe3O4-CNT) are encapsulated in a cross-linked network structure formed by sodium alginate to obtain an auxiliary electrode material. The obtained auxiliary electrode material has good conductivity, environmental friendliness and corrosion resistance. MgO-ATP in the auxiliary electrode material has good adsorption capacity for heavy metal ions, Fe3O4-CNT gives the auxiliary electrode material excellent conductivity, and the cross-linked network structure of the auxiliary electrode material has good mechanical strength and stability.

[0020] (2) The Fe3O4-CNT in the auxiliary electrode material obtained in this invention is magnetic. Compared with CNT / MgO-ATP / SA, the magnetic properties of Fe3O4-CNT / MgO-ATP / SA enable Fe3O4-CNT / MgO-ATP / SA to undergo magnetic adsorption and recycling under the action of an external magnetic field. In addition to having good ferromagnetism, Fe3O4 also has good conductivity. After Fe3O4 is combined with CNT, the conductivity of the obtained Fe3O4-CNT / MgO-ATP / SA is further improved, enhancing the current response in the electro-repair process and helping to further improve the efficiency of the electrochemical reaction.

[0021] (3) If Fe3O4 in Fe3O4-CNT / MgO-ATP / SA obtained in this invention is replaced with Fe2O3, the obtained Fe2O3-CNT / MgO-ATP / SA has a smaller magnetic field, making it difficult to collect and separate. Furthermore, Fe2O3 has poor conductivity and cannot significantly improve the removal efficiency of heavy metal pollutant ions by Fe2O3-CNT / MgO-ATP / SA during electrokinetic remediation. Attached image description:

[0022] Figure 1 : Schematic diagram of the test principle structure of the electric repair device used in this invention.

[0023] Figure 2 XRD comparison diagrams of the electrode materials obtained in Examples 1-3. Detailed implementation method:

[0024] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0025] Example 1

[0026] (1) Weigh 20g of ATP and add it to 100mL of MgCl·6H2O aqueous solution with a concentration of 1mol / L. Stir and mix evenly. Adjust the pH of the solution to 10 with 2mol / L NaOH and then transfer it to a polytetrafluoroethylene high-pressure reactor. Hydrothermal reaction is carried out at 120℃ for 6h. After the reaction is completed, cool to room temperature, collect the solid product by centrifugation, and dry it in an oven at 60℃. After drying, grind and sieve to obtain solid powder with an average particle size of 100 mesh. Place the obtained solid powder in a muffle furnace for calcination at a temperature of 500℃ for 2h. The heating rate of the muffle furnace is 10℃ / min. After calcination, MgO-ATP is obtained.

[0027] (2) Carbon nanotubes and 5 mol / L nitric acid aqueous solution were mixed evenly at a solid-liquid ratio of 1:4 and stirred at 60°C for 3 h. Then, the filtrate was washed with vacuum filtration and distilled water until neutral and dried to obtain acidified carbon nanotubes.

[0028] (3) Dissolve 1g of acidified carbon nanotubes in 100mL of distilled water and disperse them by ultrasonication at 40℃ for 30min to obtain an acidified carbon nanotube solution.

[0029] (4) Weigh 2.7g FeCl3·6H2O, 1g FeCl2·4H2O (Fe 3+ and Fe 2+ The molar ratio of 2:1) and 1g SDS were dispersed in 200mL of distilled water and stirred until evenly dispersed. Then, the mixture was stirred and mixed evenly with the carbon nanotube solution obtained in step (3). Ammonia water was added dropwise while stirring at 80℃. The dropwise addition rate of ammonia water was 1-2s / drop. When the pH was added to 8, the mixture was stirred and reacted for 60min. After the reaction was completed, a magnet was placed in the reaction solution to adsorb the solid product in the reaction solution by magnetic attraction. The obtained solid product was washed three times with acetone and dried at 80℃ for 24h. Then, it was placed in a tube furnace under nitrogen protection and calcined at 550℃ for 1h. The heating rate of the tube furnace was 3℃ / min. -1 This yields Fe3O4-CNT;

[0030] (5) Prepare 50 mL of 10 mg / mL Fe3O4-CNT aqueous solution;

[0031] (6) Take 5g of MgO-ATP and disperse it evenly in 50mL of deionized water to obtain MgO-ATP suspension;

[0032] (7) Add all of the Fe3O4-CNT aqueous solution from step (5) to the MgO-ATP suspension obtained in step (6) while adding the solution and stirring magnetically. The adding speed is 1-2 s / drop. After the addition is complete, disperse the solution by ultrasound (ultrasound power is 20W) for 2 hours and then stir (stirring speed is 500 rpm) for 6 hours to obtain a Fe3O4-CNT / MgO-ATP mixed suspension.

[0033] (8) Add 50 mL of 10 g·L⁻¹ -1 SA aqueous solution was added dropwise to the Fe3O4-CNT / MgO-ATP mixed suspension obtained in step (7), and the mixture was stirred at room temperature for 3 hours. After the reaction was completed, the reaction solution was filtered, and the obtained filter cake was frozen in an ultra-low temperature freezer (-80℃) for 12 hours, and then freeze-dried in a freeze dryer (-50℃, 10Pa) for 24 hours. The obtained sample was placed in a tube furnace and calcined at 450℃ for 30 minutes under nitrogen protection. The heating rate of the tube furnace was 3℃ / min. -1Thus, the Fe3O4-CNT / MgO-ATP / SA electrode material is obtained.

[0034] Example 2 is the same as Example 1, except that in step (5) of Example 2, the volume of the 10 mg / mL Fe3O4-CNT aqueous solution is 100 mL.

[0035] Example 3 is the same as Example 1, except that the volume of the 10 mg / mL Fe3O4-CNT aqueous solution in step (5) of Example 3 is 200 mL.

[0036] Comparative Example 1

[0037] A CNT / MgO-ATP / SA electrode material is prepared as follows:

[0038] (1) Weigh 20g of ATP and add it to 100mL of MgCl·6H2O aqueous solution with a concentration of 1mol / L. Stir and mix evenly. Adjust the pH of the solution to 10 with 2mol / L NaOH. Then transfer it to a polytetrafluoroethylene high-pressure reactor and hydrothermally react at 120℃ for 6h. After the reaction is completed, cool to room temperature, collect the solid product by centrifugation, and dry it in an oven at 60℃. After drying, grind and sieve to obtain solid powder with an average particle size of 100 mesh. Place the obtained solid powder in a muffle furnace for calcination at a temperature of 500℃ for 2h. The heating rate of the muffle furnace is 10℃ / min. After calcination, MgO-ATP is obtained.

[0039] (2) Carbon nanotubes and 5 mol / L nitric acid aqueous solution were mixed evenly at a solid-liquid ratio of 1:4 and stirred at 60°C for 3 h. Then, the filtrate was washed with vacuum filtration and distilled water until neutral and dried to obtain acidified carbon nanotubes.

[0040] (3) Dissolve 1g of acidified carbon nanotubes in 100mL of distilled water and disperse them by ultrasonication at 40℃ for 30min to obtain an acidified carbon nanotube solution.

[0041] (4) The acidified carbon nanotube solution obtained in step (3) is dried at 80°C for 24 hours to obtain acidified CNT powder;

[0042] (5) Prepare 50 mL of 10 mg / mL acidified CNT powder aqueous solution;

[0043] (6) Take 5g of MgO-ATP and disperse it evenly in 50mL of deionized water to obtain MgO-ATP suspension;

[0044] (7) Add all the acidified CNT powder aqueous solution obtained in step (5) to the MgO-ATP suspension obtained in step (6) while adding and stirring magnetically. The adding speed is 1-2 s / drop. After the addition is completed, disperse by ultrasound (ultrasound power is 20W) for 2 hours, and then stir (stirring speed is 500 rpm) for 6 hours to obtain CNT / MgO-ATP mixed suspension.

[0045] (8) Add 50 mL of 10 g·L⁻¹ -1 SA aqueous solution was added dropwise to the CNT / MgO-ATP mixed suspension obtained in step (7), and the mixture was stirred at room temperature for 3 hours. After the reaction was completed, the reaction solution was filtered, and the obtained filter cake was frozen in an ultra-low temperature freezer (-80℃) for 12 hours, and then freeze-dried in a freeze dryer (-50℃, 10Pa) for 24 hours. The obtained sample was placed in a tube furnace and calcined at 450℃ for 30 minutes under nitrogen protection. The heating rate of the tube furnace was 3℃ / min. -1 Thus, the CNT / MgO-ATP / SA electrode material is obtained.

[0046] Comparative Example 2

[0047] A Fe2O3-CNT / MgO-ATP / SA electrode material is prepared by the following method:

[0048] (1) Weigh 20g of ATP and add it to 100mL of MgCl·6H2O aqueous solution with a concentration of 1mol / L. Stir and mix evenly. Adjust the pH of the solution to 10 with 2mol / L NaOH and then transfer it to a polytetrafluoroethylene high-pressure reactor. Hydrothermal reaction is carried out at 120℃ for 6h. After the reaction is completed, cool to room temperature, collect the solid product by centrifugation, and dry it in an oven at 60℃. After drying, grind and sieve to obtain solid powder with an average particle size of 100 mesh. Place the obtained solid powder in a muffle furnace for calcination at a temperature of 500℃ for 2h. The heating rate of the muffle furnace is 10℃ / min. After calcination, MgO-ATP is obtained.

[0049] (2) Carbon nanotubes and 5 mol / L nitric acid aqueous solution were mixed evenly at a solid-liquid ratio of 1:4 and stirred at 60°C for 3 h. Then, the filtrate was washed with vacuum filtration and distilled water until neutral and dried to obtain acidified carbon nanotubes.

[0050] (3) Dissolve 1g of acidified carbon nanotubes in 100mL of distilled water and disperse them by ultrasonication at 40℃ for 30min to obtain an acidified carbon nanotube solution.

[0051] (4) Weigh 2.7g FeCl3·6H2O and 1g SDS and disperse them in 200mL distilled water. After stirring and dispersing evenly, mix them with the carbon nanotube solution obtained in step (3). Add ammonia water dropwise while stirring at 80℃. The dropwise rate of ammonia water is 1-2s / drop. When the pH is 8, stir and react for 60min. After the reaction is complete, place a magnet in the reaction solution to adsorb the solid product in the reaction solution by magnetic attraction. Wash the obtained solid product three times with acetone and dry it at 80℃ for 24h. Place it in a tube furnace under nitrogen protection and calcine it at 550℃ for 1h. The heating rate of the tube furnace is 3℃ / min. -1 This yields Fe2O3-CNT;

[0052] (5) Prepare 50 mL of 10 mg / mL Fe2O3-CNT aqueous solution;

[0053] (6) Take 5g of MgO-ATP and disperse it evenly in 50mL of deionized water to obtain MgO-ATP suspension;

[0054] (7) Add all of the Fe2O3-CNT aqueous solution from step (5) to the MgO-ATP suspension obtained in step (6) while adding the solution and stirring magnetically. The adding speed is 1-2 s / drop. After the addition is complete, disperse the solution by ultrasound (ultrasound power is 20W) for 2 hours and then stir (stirring speed is 500 rpm) for 6 hours to obtain a Fe2O3-CNT / MgO-ATP mixed suspension.

[0055] (8) Add 50 mL of 10 g·L⁻¹ -1 SA aqueous solution was added dropwise to the Fe2O3-CNT / MgO-ATP mixed suspension obtained in step (7), and the mixture was stirred at room temperature for 3 hours. After the reaction was completed, the reaction solution was filtered, and the obtained filter cake was frozen in an ultra-low temperature freezer (-80℃) for 12 hours, and then freeze-dried in a freeze dryer (-50℃, 10Pa) for 24 hours. The obtained sample was placed in a tube furnace and calcined at 450℃ for 30 minutes under nitrogen protection. The heating rate of the tube furnace was 3℃ / min. -1 Thus, the Fe2O3-CNT / MgO-ATP / SA electrode material is obtained.

[0056] The XRD patterns of the electrode materials obtained in Examples 1-3 are shown in the appendix to the instruction manual. Figure 2As shown, the test results indicate that the electrode materials obtained in Examples 1-3 all exhibited Fe3O4 (220), (422), and (440) crystal plane peaks at 2θ = 29.6°, 53.8°, and 62.1°, respectively; CNT (002) and (100) crystal plane peaks at 26.6° and 42.7°, respectively; MgO (111), (310), and (222) crystal plane peaks at 2θ = 27.8°, 73.5°, and 76.6°, respectively; and APT (110), (130), (040), (400), and (161) crystal plane peaks at 2θ = 5.8°, 17.8°, 19.8°, 21.8°, and 36.1°, respectively. The XRD characteristic peaks of sodium alginate were not obvious because it is an amorphous polymer, typically exhibiting broad and disordered diffraction peaks.

[0057] Performance testing

[0058] Experiments were conducted on the electrokinetic remediation effects of the electrode materials obtained in Examples 1-3 and Comparative Example 1 on the removal of heavy metal particles from soil. The specific test methods are as follows:

[0059] The electric repair device used in the experiment has the same structure as conventional electric repair devices in this field. A schematic diagram of the specific test principle is shown in the attached instruction manual. Figure 1 As shown, the device includes a soil remediation chamber (length × width × height = 15cm × 10cm × 10cm), a cathode chamber (length × width × height = 5cm × 10cm × 10cm), an anode chamber (length × width × height = 5cm × 10cm × 10cm), an adjustable DC regulated power supply, and two high-purity graphite electrode plates (length × width × thickness = 10cm × 10cm × 1cm). The cathode electrolyte is a mixture of 1 mol / L citric acid aqueous solution (CA) and 0.02 mol / L sodium dodecyl sulfate aqueous solution (SDS) in a volume ratio of 1:1, and the anolyte is a 1 mol / L citric acid aqueous solution (CA). The electrode materials obtained in Examples 1-3 and Comparative Examples 1-2 were pressed into sheets and used as auxiliary electrode sheets (length × width × thickness = 5cm × 3.5cm × 0.2cm) for the electroremediation devices, assembling five different electroremediation devices (only the type of auxiliary electrode sheet differed), and were tested under the same experimental conditions. The height of the cathode electrolyte or anolyte is the same as the height of the heavy metal contaminated soil sample in the soil remediation chamber. An auxiliary electrode is placed between the soil and the cathode or anolyte chamber and covered with fiber filter paper, then fixed with a perforated acrylic plate. The soil remediation chamber is separated from the cathode or anolyte chamber by a composite membrane formed by the perforated acrylic and filter paper. The perforated acrylic surface has a pore diameter of 1 mm and a pore density of 9 pores per square centimeter; the filter paper is a medium-speed filter paper with a pore diameter of 30 μm.

[0060] The principle of the electric repair experiment test is as follows:

[0061] During the experiment, a 600g sample of heavy metal contaminated soil was placed in the soil remediation chamber and compacted evenly. The high-purity graphite electrode plate was energized by the adjustable DC regulated power supply in the electric remediation device through the wires. Under the action of the electric field, cadmium and zinc metal ions in the heavy metal contaminated soil sample migrated to the cathode chamber by electromigration or electroosmosis. After the reaction was completed, the soil in the soil remediation chamber was purified.

[0062] Referring to "HJ832-2017 Microwave Digestion Method for Total Metal Elements in Soil and Sediment", this experiment digested the sample with hydrochloric acid (HCl)-perchloric acid (HClO4)-hydrofluoric acid (HF)-nitric acid (HNO3). The digestion process was completed using an acid removal instrument and a microwave digestion instrument. After dilution, the content of heavy metals in the electrically remediated contaminated soil was determined by flame atomic absorption spectrophotometer.

[0063] The preparation method for heavy metal contaminated soil samples is as follows:

[0064] Cadmium nitrate and zinc nitrate were selected as heavy metal pollutants. 826.26 mg of cadmium nitrate and 6.82 g of zinc nitrate were dissolved in 500 mL of deionized water. The heavy metal solution was added sequentially to 3 kg of soil, maintaining a moisture content of 30%. The soil was stirred for 10 minutes every 2 hours, for a total of 4 times, to promote uniform distribution of heavy metal ions in the soil. The prepared contaminated soil sample was placed in a fume hood and left to stand for 60 days until all moisture evaporated, then stored for later use, thus obtaining the heavy metal contaminated soil sample. The concentration of Cd in the heavy metal contaminated soil sample was determined. 2+ The initial concentration was 76.58 mg / kg, Zn 2+ The initial concentration was 320.38 mg / kg.

[0065] During the testing process, a graphite electrode plate was used as the main electrode, and the materials of Examples 1-3 and Comparative Examples 1-2 were used as auxiliary electrode sheets. The voltage gradient was 1.5V / cm, and the repair time was 7 days. The test results are shown in Table 1.

[0066] Table 1

[0067] Test Items <![CDATA[Cd after treatment 2+ Concentration (mg / kg)]]> <![CDATA[Cd 2+ Removal rate (%) <![CDATA[Zn after treatment 2+ Concentration (mg / kg)]]> <![CDATA[Zn 2+ Removal rate (%) Example 1 27.18 64.51 136.75 57.32 Example 2 10.58 86.18 87.95 72.55 Example 3 19.45 74.60 102.27 68.08 Comparative Example 1 43.92 42.65 189.92 40.72 Comparative Example 2 36.59 52.22 167.56 47.70

[0068] Note: The processed Cd in Table 1 2+ Concentration refers to the concentration of Cd in heavy metal contaminated soil samples after electrokinetic remediation. 2+ Concentration; Zn after treatment 2+ Concentration refers to the concentration of Zn in heavy metal contaminated soil samples after electroremediation. 2+ concentration.

[0069] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A Fe3O4-CNT / MgO-ATP / SA electrode material for electrokinetic remediation of heavy metals in soil, characterized in that, The preparation method includes the following steps: (1) Weigh 20g of ATP and add it to 100mL of MgCl•6H2O aqueous solution with a concentration of 1mol / L. Stir and mix evenly. Adjust the pH of the solution to 10 with 2mol / L NaOH and then transfer it to a polytetrafluoroethylene high-pressure reactor. Hydrothermal reaction is carried out at 120℃ for 6h. After the reaction is completed, cool to room temperature, collect the solid product by centrifugation, and dry it in an oven at 60℃. After drying, grind and sieve to obtain solid powder with an average particle size of 100 mesh. Place the obtained solid powder in a muffle furnace for calcination at a temperature of 500℃ for 2h. The heating rate of the muffle furnace is 10℃ / min. After calcination, MgO-ATP is obtained. (2) Carbon nanotubes and 5 mol / L nitric acid aqueous solution were mixed evenly at a solid-liquid ratio of 1:4 and stirred at 60°C for 3 h. Then, the filtrate was washed with vacuum filtration and distilled water until neutral and dried to obtain acidified carbon nanotubes. (3) Dissolve 1g of acidified carbon nanotubes in 100mL of distilled water and disperse them by ultrasonication at 40℃ for 30min to obtain an acidified carbon nanotube solution; (4) Weigh 2.7 g FeCl3·6H2O, 1 g FeCl2·4H2O and 1 g SDS and disperse them in 200 mL of distilled water. After stirring and dispersing evenly, mix them with the carbon nanotube solution obtained in step (3). Add ammonia water dropwise while stirring at 80 °C. The dropwise rate of ammonia water is 1-2 s / drop. When the pH=8 is reached, stir and react for 60 min. After the reaction is completed, place a magnet in the reaction solution to adsorb the solid product in the reaction solution by magnetic attraction. The obtained solid product is washed three times with acetone and dried at 80 °C for 24 h. Then, it is placed in a tube furnace under nitrogen protection and calcined at 550 °C for 1 h. The heating rate of the tube furnace is 3 °C / min. -1 This yields Fe3O4-CNT, FeCl3·6H2O, and FeCl2·4H2O. 3+ with Fe 2+ The molar ratio is 2:1; (5) Prepare 100 mL of 10 mg / mL Fe3O4-CNT aqueous solution; (6) Take 5g of MgO-ATP and disperse it evenly in 50mL of deionized water to obtain MgO-ATP suspension; (7) Add all of the Fe3O4-CNT aqueous solution from step (5) to the MgO-ATP suspension obtained in step (6) while adding the solution and stirring magnetically. The adding speed is 1-2 s / drop. After the addition is complete, disperse the solution by ultrasound for 2 hours and then stir for 6 hours to obtain a Fe3O4-CNT / MgO-ATP mixed suspension. The ultrasound power is 20W and the stirring speed is 500 rpm. (8) Add 50 mL of 10 g·L⁻¹ -1 SA aqueous solution was added dropwise to the Fe3O4-CNT / MgO-ATP mixed suspension obtained in step (7), and the mixture was stirred at room temperature for 3 hours. After the reaction was completed, the reaction solution was filtered, and the obtained filter cake was frozen in an ultra-low temperature freezer for 12 hours and then freeze-dried in a freeze dryer for 24 hours. The obtained sample was placed in a tube furnace and calcined at 450°C for 30 minutes under nitrogen protection. The heating rate of the tube furnace was 3°C / min. -1 The Fe3O4-CNT / MgO-ATP / SA electrode material was obtained by using an ultra-low temperature freezer at -80℃, a freeze dryer at -50℃, and a freeze dryer at a pressure of 10Pa.

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