Preparation method of magnetic spinel adsorption electrode and application thereof

Abstract

The application belongs to the technical field of environmental electrocatalytic electrode preparation, and particularly relates to a preparation method of a magnetic spinel adsorption electrode and application thereof. The specific preparation steps are as follows: 1) dispersing the magnetic spinel catalyst in an electrolyte to form a suspension system; 2) constructing a double-electrode electrochemical system in the suspension system by taking foamed nickel as a cathode; and 3) stirring the suspension system, performing electrolysis reaction, and obtaining the magnetic spinel adsorption electrode after drying. The prepared adsorption electrode does not need to add an additional binder to realize the fixation of the magnetic spinel catalyst on the foamed nickel substrate, overcomes the problem of sharp reduction of the number of active sites and conductivity caused by the binder, and greatly improves the electrode catalytic degradation capacity. In addition, the preparation method does not need to consume additional binders and organic solvents, can effectively reduce the synthesis cost of the spinel electrode and reduce the discharge of waste liquid, and is an environmentally friendly catalyst synthesis method.

Description

Technical Field

[0001] This invention belongs to the field of environmental electrocatalytic electrode preparation technology, specifically relating to a method for preparing a magnetic spinel adsorption type electrode and its application. Background Technology

[0002] Over the past few decades, water pollution has become a serious environmental problem affecting our health. To effectively remove emerging pollutants from water (such as endocrine disruptors), advanced oxidation technologies based on persulfate electrocatalytic activation have attracted widespread attention from researchers due to their low energy consumption and environmental friendliness.

[0003] To date, researchers have developed various persulfate electro-activation catalysts for water pollution remediation, such as perovskite oxides, spinel oxides, metal sulfides, and layered bimetallic hydroxides. Among these catalysts, spinel oxides (AB₂O₄) are considered promising persulfate electro-activation catalysts due to their high stability and catalytic activity. A key aspect of persulfate-based electrocatalytic activation of advanced oxidation technologies is the preparation of highly active electrocatalytic electrodes. Coating is a commonly used method for preparing electrocatalytic electrodes. However, this method requires additional binders and organic solvents, which can cover the catalyst's active sites and reduce electrode conductivity, significantly decreasing the electrode's ability to electrocatalytically activate persulfate, thus substantially reducing the catalytic degradation efficiency of new pollutants. Therefore, developing new methods for preparing highly active persulfate electrocatalytic activation electrodes is of significant practical importance.

[0004] The magnetic spinel adsorption electrode prepared in this invention can fix the magnetic spinel catalyst on a nickel foam substrate without the addition of additional binders, overcoming the problem of a sharp reduction in the number of effective active sites and conductivity of the catalyst caused by binders, thereby greatly improving the electrode's ability to catalyze the degradation of new pollutants in water. Simultaneously, the magnetic spinel catalyst on this electrode is uniformly distributed, which helps expose the active sites. Furthermore, the preparation method proposed in this paper does not require additional binders and organic solvents, effectively reducing the synthesis cost of the spinel electrode and reducing wastewater discharge, making it an environmentally friendly catalyst synthesis method. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a method for preparing a magnetic spinel adsorption electrode and its application. The main technical solution involves the successful preparation of a magnetic spinel adsorption electrode through an environmentally friendly magnetoelectric synergistic method. Its formation is the result of the combined action of a magnetic field and an electric field. Under this action, the magnetic spinel catalyst can be directionally and uniformly adsorbed onto nickel foam, which helps expose the catalytic active sites and overcomes the problem of a sharp decrease in the number of effective active sites and conductivity of the catalyst caused by binders. This significantly improves the electrode's ability to catalyze the activation of persulfate and the degradation of new pollutants in water.

[0006] The objective of this invention can be achieved through the following methods:

[0007] This invention provides a method for preparing a magnetic spinel adsorption type electrode, comprising the following steps:

[0008] (1) The magnetic spinel catalyst is dispersed in the electrolyte to form a suspension system;

[0009] (2) In a suspension system, a two-electrode electrochemical system was constructed using nickel foam as the cathode;

[0010] (3) An electrolysis reaction is carried out through a dual-electrode electrochemical system. After the reaction is completed, the magnetic spinel adsorption electrode is obtained.

[0011] As one embodiment of the present invention, in step (1), the magnetic spinel is AFe2O4, wherein A is a divalent metal, and A includes one of Zn, Co, Cu, Ni, Mn, Mg and Fe.

[0012] As one embodiment of the present invention, in step (1), the magnetic spinel includes one or more of ZnFe2O4, CoFe2O4, CuFe2O4, NiFe2O4, MnFe2O4, MgFe2O4, and Fe3O4.

[0013] In one embodiment of the present invention, in step (1), the electrolyte includes one or more of sodium sulfate solution, sodium chloride solution, potassium sulfate solution, and potassium chloride solution. The concentration of the electrolyte is 10 mmol / L or higher, preferably 10-100 mmol / L.

[0014] As one embodiment of the present invention, in step (1), the dispersion method is ultrasonic or stirring, and the dispersion time is 10 min or more, preferably 10-30 min.

[0015] As one embodiment of the present invention, in step (1), the ratio of magnetic spinel catalyst to electrolyte is 5-20 mg: 50 mL, preferably 13-20 mg: 50 mL.

[0016] As one embodiment of the present invention, in step (2), the anode in the dual-electrode electrochemical system is an electrode that can be used as an anode, such as a ruthenium-iridium-titanium electrode, a graphite rod electrode, or a Pt electrode.

[0017] In one embodiment of the present invention, in step (3), the current density during the electrolysis reaction is 0.5-10 mA / cm². 2 Preferably 0.5-4 mA / cm 2 If the current is too high, the deposition will be too fast, resulting in poor uniformity and thus poor performance.

[0018] In one embodiment of the present invention, in step (3), the electrolysis reaction time is 10 min or more, preferably 10-30 min.

[0019] In one embodiment of the present invention, during step (3), the suspension system is stirred at a speed of 400-800 rpm, preferably 600 rpm, during the electrolysis reaction. Stirring is to disperse the catalyst, which is beneficial for the uniform adsorption of magnetic spinel.

[0020] As one embodiment of the present invention, in step (3), the obtained magnetic spinel adsorption electrode is further dried; the drying temperature is 60-105℃ and the time is 6-12h.

[0021] As one embodiment of the present invention, the preparation method does not require the consumption of additional binders and organic solvents.

[0022] This invention also provides the application of the magnetic spinel adsorption electrode prepared by the above method in the catalytic activation of persulfate degradation of pollutants. Pollutants include bisphenol A, tetracycline hydrochloride, ciprofloxacin, glyphosate, and chlorophenols.

[0023] The magnetic spinel adsorption electrode obtained by this invention has magnetic spinel adsorbed on the surface in a loosely packed state, which can be desorbed by subsequent ultrasonic treatment. The method of this invention is simple to prepare, can be mass-produced, and has good stability.

[0024] If magnetic spinel is coated on the surface of nickel foam, its microstructure is uneven and tightly stacked, resulting in fewer exposed effective active sites and a sharp decrease in conductivity.

[0025] If magnetic spinel is generated in situ on the surface of nickel foam, its microstructure is dense with few effective active sites. It is prone to falling off after multiple reactions, and the effect decreases significantly after falling off. It is difficult to easily recover the catalyst and it is difficult to easily regenerate after deactivation.

[0026] The magnetic spinel catalyst of the present invention can be directionally and uniformly adsorbed on nickel foam. The orientation is determined by the magnetic field, and the uniformity is determined by the electric field. This is because magnetic materials are bound to be adsorbed on nickel foam. However, if an electric field is added, hydrogen evolution will occur during electrolysis. The generation of hydrogen will cause the over-stacked catalyst particles to fall off, thereby making the adsorption electrode grow uniformly on the surface of nickel foam.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The preparation of magnetic spinel adsorption type electrode and its catalytic degradation of new pollutants in wastewater were achieved;

[0029] (2) The proposed new preparation method can fix the magnetic spinel catalyst on the nickel foam substrate without the need for additional binders, overcoming the problem of a sharp decrease in the number of effective active sites and conductivity of the catalyst caused by binders. At the same time, the magnetic spinel catalyst on the electrode is uniformly distributed, which helps to expose the active sites and greatly improves the electrode's ability to catalyze the activation of persulfate and the degradation of new pollutants in water.

[0030] (3) The preparation method proposed in this paper does not require additional binders and organic solvents, which can effectively reduce the synthesis cost of spinel electrodes and reduce the discharge of waste liquid. It is an environmentally friendly catalyst synthesis method. Attached Figure Description

[0031] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1 Images of the magnetic spinel adsorption electrode prepared in Example 1 (left, ZnFe2O4@NF) and the magnetic spinel coated electrode prepared in Comparative Example 2 (right, ZnFe2O4 / NF);

[0033] Figure 2 The graph shows the effect of Example 1, Comparative Example 1, and Comparative Example 2 on the degradation performance of the new pollutant. In the graph, a is the effect of different systems on the degradation performance of bisphenol A by catalytic activation of persulfate, and b is the corresponding pseudo-first-order kinetic fitting curve.

[0034] Figure 3 The graph shows the effect of different spinel adsorption amounts prepared in Examples 1-4 on the degradation performance of new pollutants. In this graph, a is the effect of different ZnFe2O4 adsorption amounts on the catalytic activation of persulfate degradation of bisphenol A, and b is the corresponding pseudo-first-order kinetic fitting curve. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following examples are implemented under the premise of the technical solution of the present invention, providing detailed implementation methods and specific operating procedures, which will help those skilled in the art to further understand the present invention. It should be noted that the scope of protection of the present invention is not limited to the following embodiments; any adjustments and improvements made under the concept of the present invention are all within the scope of protection of the present invention.

[0036] The magnetic spinel adsorption electrode prepared by this invention can fix the magnetic spinel catalyst on a nickel foam substrate without the need for additional binders, overcoming the problem of a sharp reduction in the number of effective active sites and conductivity caused by binders, thereby greatly improving the electrode's ability to catalytically degrade new pollutants in water. Simultaneously, the magnetic spinel catalyst on this electrode is uniformly distributed, which helps expose the active sites. Furthermore, the preparation method proposed in this invention does not require additional binders and organic solvents, effectively reducing the synthesis cost of the spinel electrode and reducing wastewater discharge, making it an environmentally friendly catalyst synthesis method.

[0037] Example 1

[0038] (1) 15 mg ZnFe2O4 was sonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0039] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0040] (3) At 2mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0041] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF or ZnFe2O4@NF-0.3 g·L⁻¹). -1 );

[0042] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF or ZnFe2O4@NF-0.3 g·L) -1 The system was composed of ruthenium-iridium-titanium electrodes and a performance evaluation system. Then, under stirring conditions, 0.1 g·L⁻¹ of the ruthenium-iridium-titanium electrode was added. -1 A potassium persulfate complex salt that provides 2 mA / cm 2 The current density, and the degradation concentration is 2 mg·L⁻¹ -1The catalytic activity of bisphenol A was measured, and it was found that the degradation rate of bisphenol A reached 85% within 80 minutes. The concentration of bisphenol A was determined by high performance liquid chromatography.

[0043] Simultaneously, using this magnetic ZnFe2O4 adsorption electrode, it also exhibits good degradation effects on pollutants such as tetracycline hydrochloride, ciprofloxacin, glyphosate, and chlorinated phenols.

[0044] The adsorption electrode can be desorbed and recovered by ultrasonic treatment to obtain ZnFe2O4 particles.

[0045] Example 2

[0046] (1) Disperse 5 mg ZnFe2O4 in 50 mL of 10 mmol / L sodium sulfate solution by sonication for 10 min to form a suspension system;

[0047] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0048] (3) At 2mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0049] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.1g·L). -1 );

[0050] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.1g·L) -1 In the presence of potassium persulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 20.5% within 80 min.

[0051] Example 3

[0052] (1) 10 mg ZnFe2O4 was ultrasonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0053] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0054] (3) At 2mA / cm 2Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0055] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.2g·L). -1 );

[0056] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.2g·L) -1 In the presence of potassium persulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 52.8% within 80 min.

[0057] Example 4

[0058] (1) Disperse 20 mg ZnFe2O4 in 50 mL of 10 mmol / L sodium sulfate solution by sonication for 10 min to form a suspension system;

[0059] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0060] (3) At 2mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0061] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.4g·L). -1 );

[0062] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.4g·L) -1 In the presence of potassium persulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 77.5% within 80 min.

[0063] Example 5

[0064] (1) 15 mg ZnFe2O4 was sonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0065] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0066] (3) At 4mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0067] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.3g·L). -1 -4mA / cm 2 );

[0068] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.3g·L) -1 -4mA / cm 2 In the presence of potassium persulfate complex salt and 4 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 90.1% within 80 min.

[0069] Example 6

[0070] (1) 15 mg ZnFe2O4 was sonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0071] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0072] (3) At 10mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0073] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.3g·L). -1 -10mA / cm 2 );

[0074] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF-0.3g·L) -1 -10mA / cm 2 In the presence of potassium persulfate complex salt and 10 mA / cm 2The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 25.6% within 80 min.

[0075] Example 7

[0076] (1) 15 mg CoFe2O4 was sonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0077] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0078] (3) At 2mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0079] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic CoFe2O4 adsorption electrode (CoFe2O4@NF-0.3g·L). -1 );

[0080] (5) The prepared magnetic CoFe2O4 adsorption electrode (CoFe2O4@NF-0.3g·L) -1 In the presence of potassium persulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 92.8% within 80 min.

[0081] Example 8

[0082] (1) 15 mg MnFe2O4 was sonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0083] (2) In the system obtained in (1), with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0084] (3) At 2mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0085] (4) After the reaction in (3) is completed, the cathode is dried in an oven at 60°C to obtain a magnetic MnFe2O4 adsorption electrode (MnFe2O4@NF-0.3g·L). -1 );

[0086] (5) The prepared magnetic MnFe2O4 adsorption electrode (MnFe2O4@NF-0.3g·L) -1 In the presence of potassium persulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 95.8% within 80 min.

[0087] Comparative Example 1

[0088] (1) In 50 mL of 10 mmol / L sodium sulfate solution, with an area of ​​6 cm² 2 A two-electrode electrochemical system was constructed using nickel foam as the cathode and ruthenium-iridium-titanium as the anode.

[0089] (2) At 2mA / cm 2 Under a current density of 100 rpm, the suspension system was slowly stirred (600 rpm) and the electrolysis reaction was carried out for 10 min.

[0090] (3) After the reaction in (3) is completed, the cathode is placed in a 60°C oven for drying to obtain a non-magnetic ZnFe2O4 electrode (NF);

[0091] (4) The prepared non-magnetic ZnFe2O4 electrode (NF) was placed in the presence of potassium peroxymonosulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 18.1% within 80 min.

[0092] Comparative Example 2

[0093] (1) 15 mg ZnFe2O4 was sonicated for 10 min to disperse it in a mixed solution containing 250 μL deionized water, 750 μL anhydrous ethanol and 30 μL Nafion solution (5 wt%) to form a suspension system;

[0094] (2) The entire suspension system obtained in (1) was dripped onto a surface with an area of ​​6 cm². 2 On the nickel foam;

[0095] (3) The drop-coated nickel foam obtained in (2) was dried in an oven at 60°C to obtain a magnetic ZnFe2O4 coated electrode (ZnFe2O4 / NF);

[0096] (4) The prepared magnetic ZnFe2O4-coated electrode (ZnFe2O4 / NF) with an unevenly packed morphology was placed in the presence of potassium peroxymonosulfate composite salt and 2 mA / cm 2The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 34.0% within 80 min.

[0097] Comparative Example 3

[0098] (1) 15 mg ZnFe2O4 was sonicated for 10 min to disperse it in 50 mL of 10 mmol / L sodium sulfate solution to form a suspension system;

[0099] (2) Stir the suspension system slowly (600 rpm) and let it stand for 10 min without current supply;

[0100] (3) The cathode treated in (2) was placed in a 60°C oven for drying to obtain a ZnFe2O4 adsorption electrode (ZnFe2O4@NF-no electric field);

[0101] (4) The prepared ZnFe2O4 adsorption electrode (ZnFe2O4@NF-no electric field) was placed in the presence of potassium peroxymonosulfate complex salt and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by decreasing the current density. The test method was the same as in Example 1. It was found that the degradation rate of bisphenol A reached 67.5% within 80 min.

[0102] The preparation method of the comparative magnetic adsorption electrode is basically the same as that of Example 1, except that: nickel foam is placed in a suspension system, and a two-electrode electrochemical system is not constructed. Instead, the suspension system is slowly stirred for 20 minutes, and the electrode is prepared by relying on the magnetic adsorption of ZnFe2O4.

[0103] The magnetic spinel adsorption type electrode prepared in Example 1 of this invention is as follows: Figure 1 As shown in the left figure, the magnetic spinel-coated electrode prepared in Comparative Example 2 is as follows: Figure 1 As shown in the right figure;

[0104] The effects of Example 1, Comparative Example 1, and Comparative Example 2 on the degradation performance of new pollutants are as follows: Figure 2 As shown;

[0105] The effects of different spinel adsorption capacities prepared in Examples 1-4 on the degradation performance of new pollutants are as follows: Figure 3 As shown.

[0106] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a magnetic spinel adsorption type electrode, characterized in that, Includes the following steps: (1) The magnetic spinel catalyst is dispersed in the electrolyte to form a suspension system; (2) In the suspension system, a two-electrode electrochemical system is constructed using nickel foam as the cathode; (3) An electrolysis reaction is carried out through a two-electrode electrochemical system. After the reaction is completed, the magnetic spinel adsorption type electrode is obtained. In step (1), the magnetic spinel is one or more of ZnFe2O4, CoFe2O4, and MnFe2O4; In step (1), the ratio of magnetic spinel catalyst to electrolyte is 15-20 mg: 50 mL; In step (3), the current density during the electrolysis reaction is 0.5~4 mA / cm². 2 .

2. The method for preparing a magnetic spinel adsorption type electrode according to claim 1, characterized in that, In step (1), the electrolyte includes one or more of sodium sulfate solution, sodium chloride solution, potassium sulfate solution, and potassium chloride solution.

3. The method for preparing a magnetic spinel adsorption type electrode according to claim 1, characterized in that, In step (2), the anode in the dual-electrode electrochemical system is one of the following: ruthenium-iridium-titanium electrode, graphite rod electrode, and Pt electrode.

4. The method for preparing a magnetic spinel adsorption type electrode according to claim 1, characterized in that, In step (3), the electrolysis reaction takes 10-30 min.

5. The method for preparing a magnetic spinel adsorption type electrode according to claim 1, characterized in that, In step (3), during the electrolysis reaction, the suspension system is stirred at a speed of 400-800 rpm.

6. The method for preparing a magnetic spinel adsorption type electrode according to claim 1, characterized in that, In step (3), the obtained magnetic spinel adsorption electrode is also dried; the drying temperature is 60~105 °C and the time is 6-12h.

7. The application of a magnetic spinel adsorption electrode prepared by the method described in claim 1 in the catalytic activation of persulfate degradation of pollutants.

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