Preparation method and application of magnetic spinel adsorption type electrode

Abstract

The invention belongs to the technical field of environmental electro-catalysis electrode preparation, and particularly relates to a preparation method and application of a magnetic spinel adsorption type electrode. The preparation method comprises the following specific preparation steps: 1) dispersing a magnetic spinel catalyst in an electrolyte to form a suspension system; 2) constructing a dual-electrode electrochemical system by taking foamed nickel as a cathode in the suspension system; and (3) stirring the suspension system, carrying out electrolytic reaction, and drying to obtain the magnetic spinel adsorption type electrode. According to the prepared adsorption type electrode, the magnetic spinel catalyst can be fixed on the foamed nickel substrate without adding an additional binder, the problem that the number of active sites and the conductivity are suddenly reduced due to the binder is solved, and the catalytic degradation capacity of the electrode is greatly improved. Besides, 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 environment-friendly catalyst synthesis method.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental electrocatalytic electrode preparation, and in particular relates to a preparation method of a magnetic spinel adsorption-type electrode and application thereof. Background Art

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

[0003] So far, through the efforts of researchers, various persulfate electroactivation catalysts for water pollution remediation have been developed, such as perovskite-type oxides, spinel-type oxides, metal sulfides, layered double hydroxides, etc. Among these catalysts, spinel-type oxides (AB2O4) are considered to be promising persulfate electroactivation catalysts due to their high stability and high catalytic activity. The key to advanced oxidation technology based on persulfate electrocatalytic activation is the preparation of highly active electrocatalytic electrodes. The coating method is currently a commonly used method for preparing electrocatalytic electrodes. However, this method requires additional binders and organic solvents during the preparation process, which will cover the catalyst active sites and reduce the electrode conductivity, greatly reducing the ability of the electrode to electrocatalytically activate persulfate, thereby significantly reducing the catalytic degradation efficiency of new pollutants. Therefore, the development of new methods for preparing highly active persulfate electrocatalytic activation electrodes is of great practical significance.

[0004] The magnetic spinel adsorption electrode prepared by the present invention can fix the magnetic spinel catalyst on the nickel foam substrate without the addition of additional binders, overcoming the problem of a sharp decrease in the number of effective active sites and conductivity of the catalyst caused by the binder, thereby greatly improving the ability of the electrode to catalytically degrade new pollutants in water. At the same time, the magnetic spinel catalyst on the electrode is evenly distributed, which helps to expose the active sites. In addition, the preparation method proposed in this article does not require the consumption of 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. Summary of the Invention

[0005] The present invention addresses 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 is to successfully prepare a magnetic spinel adsorption electrode using an environmentally friendly magnetoelectric synergy method. Its formation results from the combined action of magnetic and electric fields, under which the magnetic spinel catalyst can be uniformly and directionally adsorbed on the nickel foam, facilitating the exposure of catalytically active sites and overcoming the problem of a sudden decrease in the number of effective active sites and conductivity of the catalyst caused by the binder. This significantly improves the electrode's ability to catalytically activate persulfate and degrade new pollutants in water.

[0006] The purpose of the present invention can be achieved by the following solutions:

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

[0008] (1) dispersing the magnetic spinel catalyst 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 electrolytic reaction is carried out through a double-electrode electrochemical system. After the reaction is completed, the magnetic spinel adsorption type electrode is obtained.

[0011] As an 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 an 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] As one embodiment of the present invention, in step (1), the electrolyte comprises 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 above, preferably 10-100 mmol / L.

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

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

[0016] As an 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] As an embodiment of the present invention, in step (3), the current density during the electrolysis reaction is 0.5-10 mA / cm 2 , preferably 0.5-4 mA / cm 2 If the current is too large, the deposition will be too fast and the uniformity will be poor, resulting in poor performance.

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

[0019] As an embodiment of the present invention, in step (3), during the electrolysis reaction, the suspension system is stirred at a stirring speed of 400-800 rpm, preferably 600 rpm. The stirring is to disperse the catalyst and facilitate uniform adsorption of the magnetic spinel.

[0020] As an embodiment of the present invention, in step (3), the obtained magnetic spinel adsorption-type electrode is further subjected to a drying treatment; the drying temperature is 60-105° C., and the drying time is 6-12 hours.

[0021] As an embodiment of the present invention, the preparation method does not require consumption of additional binder and organic solvent.

[0022] The present invention also provides an application of the magnetic spinel adsorption electrode prepared by the preparation method in catalytic activation of persulfate to degrade pollutants, including bisphenol A, tetracycline hydrochloride, ciprofloxacin, glyphosate, chlorinated phenols, and the like.

[0023] The magnetic spinel adsorption type electrode obtained by the present invention has magnetic spinel adsorbed on the surface in a fluffy stacked state, which can be desorbed by subsequent ultrasonic treatment. The method of the present invention is simple to prepare, can be prepared on a large scale, and has good stability.

[0024] For example, when magnetic spinel is coated on the surface of nickel foam, its microstructure is uneven and tightly stacked, resulting in few exposed active sites and a sharp drop 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 easy to fall off after multiple reactions, and its effect decreases significantly after falling off. It is difficult to simply recover the catalyst and it is difficult to simply regenerate after deactivation.

[0026] The magnetic spinel catalyst of the present invention can be uniformly adsorbed on the nickel foam in a directional manner. The orientation is determined by the magnetic field, and the uniformity is determined by the electric field. This is because the magnetic material is inevitably adsorbed on the nickel foam. However, if an electric field is added, hydrogen evolution will occur during electrolysis. The generation of hydrogen causes excessively stacked catalyst particles to fall off, thereby allowing the adsorption-type electrode to grow uniformly on the surface of the nickel foam.

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

[0028] (1) The preparation of magnetic spinel adsorption electrodes and their 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 addition of additional binders, overcoming the problem of a sudden decrease in the number of effective active sites and conductivity of the catalyst caused by the binder. At the same time, the magnetic spinel catalyst on the electrode is evenly distributed, which helps to expose the active sites and greatly improves the electrode's ability to catalyze the activation of persulfate and degrade new pollutants in water.

[0030] (3) The preparation method proposed in this paper does not require the consumption of additional binders and organic solvents, can effectively reduce the synthesis cost of spinel electrodes and reduce the discharge of waste liquid, and is an environmentally friendly catalyst synthesis method. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0033] Figure 2 Graphs showing the effects of Example 1, Comparative Example 1, and Comparative Example 2 on the degradation performance of new pollutants, wherein a is a graph showing the effects of different systems on the degradation performance of bisphenol A by catalytically activated peroxymonosulfate, and b is the corresponding pseudo-first-order kinetic fitting curve;

[0034] Figure 3 Figure 1 is a graph showing the effect of different spinel adsorption amounts on the degradation performance of new pollutants prepared in Examples 1-4, wherein a is a graph showing the effect of different ZnFe2O4 adsorption amounts on the catalytic activation of peroxymonosulfate for the degradation of bisphenol A, and b is the corresponding pseudo-first-order kinetic fitting curve; DETAILED DESCRIPTION

[0035] The present invention is described in detail below 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, provide detailed implementation methods and specific operating procedures, and will help those skilled in the art to further understand the present invention. It should be pointed out that the scope of protection of the present invention is not limited to the following embodiments, and a number of adjustments and improvements made under the premise of the concept of the present invention all fall within the scope of protection of the present invention.

[0036] The magnetic spinel adsorption electrode prepared by the present invention can fix the magnetic spinel catalyst on the foam nickel substrate without the addition of additional binder, overcoming the problem of a sharp decrease in the number of effective active sites and conductivity of the catalyst caused by the binder, thereby greatly improving the ability of the electrode to catalytically degrade new pollutants in water. At the same time, the magnetic spinel catalyst on the electrode is evenly distributed, which helps to expose the active sites. In addition, the preparation method proposed by the present invention does not require the consumption of 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.

[0037] Example 1

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

[0039] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0041] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying to obtain a magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF or ZnFe2O4@NF-0.3g·L -1 );

[0042] (5) The prepared magnetic ZnFe2O4 adsorption electrode (ZnFe2O4@NF or ZnFe2O4@NF-0.3g·L -1 ) and ruthenium-iridium-titanium electrode to form a performance evaluation system, and then 0.1g·L -1 Potassium peroxymonosulfate complex and provides 2mA / cm 2 The current density and the degradation concentration were 2 mg·L -1The catalytic activity of bisphenol A was tested by high performance liquid chromatography (HPLC).

[0043] At the same time, the magnetic ZnFe2O4 adsorption electrode can be used to degrade pollutants such as tetracycline hydrochloride, ciprofloxacin, glyphosate, and chlorophenol, and it also has a good degradation effect.

[0044] The adsorption-type electrode can be subjected to ultrasonic treatment to desorb and recover ZnFe2O4 particles.

[0045] Example 2

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

[0047] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0049] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying 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 and 2 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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) Disperse 10 mg of ZnFe2O4 in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0053] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0055] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying 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 and 2 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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) 20 mg of ZnFe2O4 was dispersed in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0059] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0061] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying 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 and 2 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 of ZnFe2O4 was dispersed in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0065] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0067] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying 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 and 4 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 of ZnFe2O4 was dispersed in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0071] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0073] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying 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 and 10 mA / cm 2The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 of CoFe2O4 was dispersed in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0077] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0079] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying to obtain a magnetic CoFe2O4 adsorption type 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 and 2 mA / cm 2 The catalytic activity of bisphenol A was measured by degrading bisphenol A at a current density of 100 nm. 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 of MnFe2O4 was dispersed in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0083] (2) In the system obtained in (1), an area of ​​6 cm 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0085] (4) The cathode after the reaction in (3) was placed in a 60°C oven for drying 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 and 2 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 50mL of 10mmol / L sodium sulfate solution, a 2 The nickel foam is used as cathode and ruthenium-iridium-titanium as anode to construct a dual-electrode electrochemical system;

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

[0090] (3) drying the cathode after the reaction in (3) in an oven at 60°C to obtain a non-magnetic ZnFe2O4 electrode (NF);

[0091] (4) The prepared non-magnetic ZnFe2O4 electrode (NF) was placed in the presence of potassium persulfate complex salt and 2 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 of ZnFe2O4 was dispersed in a mixture of 250 μL of deionized water, 750 μL of anhydrous ethanol, and 30 μL of Nafion solution (5 wt%) by ultrasonication for 10 min to form a suspension system;

[0094] (2) Apply the suspension system obtained in (1) to an area of ​​6 cm 2 On the nickel foam;

[0095] (3) drying the drop-coated nickel foam obtained in (2) 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 uneven and tightly stacked morphology was placed in the presence of potassium persulfate complex salt and 2 mA / cm 2The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 of ZnFe2O4 was dispersed in 50 mL of 10 mmol / L sodium sulfate solution by ultrasonication for 10 min to form a suspension system;

[0099] (2) Slowly stir the suspension system (600 rpm) and leave it for 10 min without current supply;

[0100] (3) The cathode treated in (2) was placed in an oven at 60°C for drying to obtain a ZnFe2O4 adsorption-type 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 persulfate complex salt and 2 mA / cm 2 The catalytic activity of the catalyst was tested by degrading bisphenol A at a current density of 100 nm. 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 magnetic adsorption type electrode in this comparative example is basically the same as that in Example 1, except that the nickel foam is placed in the suspension system, and no dual-electrode electrochemical system is constructed. The suspension system is simply 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 the present 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 the adsorption capacity of different spinels prepared in Examples 1-4 on the degradation performance of new pollutants are shown in Figure 2. Figure 3 shown.

[0106] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications 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: The steps include: (1) dispersing the magnetic spinel catalyst in an electrolyte to form a suspension system; (2) In a suspension system, a dual-electrode electrochemical system is constructed using nickel foam as the cathode; (3) An electrolytic reaction is carried out through a double-electrode electrochemical system. After the reaction is completed, the magnetic spinel adsorption electrode is obtained.

2. The method for preparing a magnetic spinel adsorption-type electrode according to claim 1, characterized in that: In step (1), the magnetic spinel includes one or more of ZnFe2O4, CoFe2O4, CuFe2O4, NiFe2O4, MnFe2O4, MgFe2O4, and Fe3O4.

3. 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.

4. The method for preparing a magnetic spinel adsorption-type electrode according to claim 1, characterized in that: In step (1), the usage ratio of magnetic spinel catalyst and electrolyte is 5-20 mg:50 mL.

5. 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 a ruthenium-iridium-titanium electrode, a graphite rod electrode, and a Pt electrode.

6. The method for preparing a magnetic spinel adsorption-type electrode according to claim 1, characterized in that: In step (3), the current density during the electrolysis reaction is 0.5 to 10 mA / cm 2 .

7. The method for preparing a magnetic spinel adsorption-type electrode according to claim 1, characterized in that: In step (3), the electrolysis reaction time is 10-30 minutes.

8. 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 stirring speed of 400-800 rpm.

9. 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-type electrode is further subjected to a drying treatment; the drying treatment temperature is 60-105° C. and the time is 6-12 hours.

10. Use of the magnetic spinel adsorption-type electrode prepared by the preparation method according to claim 1 in catalytic activation of persulfate to degrade pollutants.

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