In-situ analysis device and method for producing hydroxyl radicals by electro-Fenton method

Abstract

The invention discloses an in-situ analysis device and method for hydroxyl radicals produced by an electro-Fenton method, and relates to the technical field of electrochemical analysis, the device comprises a metal shielding shell, a micrometer displacement sliding table, an in-situ electrolytic tank, a high-resolution camera, a shockproof optical platform, an electrochemical workstation and a data analysis computer; the shockproof optical platform is arranged on the bottom surface in the metal shielding shell; the in-situ electrolytic tank, a micrometer displacement sliding table and a high-resolution camera for observing the in-situ electrolytic tank in real time are arranged on the shockproof optical platform; a first working electrode is arranged on the micrometer displacement sliding table; a second working electrode is arranged in the in-situ electrolytic tank; the electrochemical workstation is electrically connected with the first working electrode and the second working electrode respectively and is used for acquiring electrochemical signals in real time; the data analysis computer is electrically connected with the electrochemical workstation and is used for analyzing, processing and displaying electrochemical data in real time; the problems that the reaction process cannot be dynamically monitored and the sensitivity is low in the prior art are solved.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical analysis, and in particular to an in-situ analysis device and method for generating hydroxyl radicals by an electro-Fenton method. Background Art

[0002] Hydroxyl radical (•OH) is one of the most oxidizing substances among reactive oxygen species (ROS). Its detection is of great value in the fields of environmental pollutant degradation, photo / electrocatalytic mechanism research, and biological oxidative stress reaction analysis. However, due to the extremely short lifetime (nanosecond level) of •OH, low concentration and extremely high reactivity, its direct detection in real time faces great challenges. The commonly used methods for detecting hydroxyl radicals include electron spin resonance (ESR), high performance liquid chromatography (HPLC), spectrophotometry, fluorescence spectrophotometry, etc. Electron spin resonance (Electron invented Spin invented Resonance) or electron paramagnetic resonance (Electron invented Paramagnetic invented Resonance) was developed in 1945. Its main research objects are free radicals with unpaired electrons and transition metal ions and their compounds. First, a spin trap (such as DMPO) is used to form a stable spin adduct (DMPO-OH) with the hydroxyl radical (•OH), and then the signal intensity is analyzed by ESR spectroscopy. The ESR spectrum of the spin adduct produced by it and ·OH shows a characteristic spectral line that is particularly easy to identify, which is shown as a spectral signal intensity of 1:2:2:1. The free radical structure information obtained through the characteristic spectral line is highly specific. However, this detection method has many defects: 1. Poor real-time performance: the sample needs to be processed offline, and the reaction process cannot be dynamically monitored; 2. The detection limit is usually ≥1 μM, which is difficult to meet the needs of low-concentration systems; 3. Strong equipment dependence: large ESR instruments and professional operators are required, which is costly.

[0003] Although indirect detection methods such as spectrophotometry and high performance liquid chromatography are simpler to operate than ESR, and are not highly equipment-dependent, and do not require professional operators to operate, they can use •OH to oxidize specific substrates to generate color-developing substances or use salicylic acid, DMSO, etc. as capture agents, separate and detect •OH reaction products through HPLC, and indirectly reflect •OH concentration through absorbance changes. Although the above detection methods provide a variety of hydroxyl radical •OH detection pathways, they are all offline operations, with cumbersome analysis steps and long cycles, and cannot dynamically track the hydroxyl radical •OH generation kinetics. In the process of studying some reaction mechanisms, such as the generation of •OH and O in certain electrode materials under a certain potential range, 2If there is a competitive relationship between the generation of •OH and the formation of •OH, then by real-time monitoring of the generation and decay process of •OH, researchers can have a deeper understanding of the reaction path of •OH in the electrocatalytic reaction. Dynamic real-time tracking of the generation kinetics of •OH by hydroxyl radicals can help reveal the reaction mechanism of •OH under different environments, help to deeply understand the reaction mechanism of the electrode surface, and provide a certain basis for optimizing the electrocatalytic reaction conditions. However, in selecting a suitable hydroxyl radical detection method, it is necessary to comprehensively consider factors such as detection sensitivity, specificity, operation complexity and cost. Spectrophotometry and fluorescence photometry are suitable for high-throughput detection, while ESR and laser-induced fluorescence imaging are suitable for high specificity and high precision. HPLC is highly efficient and sensitive, but the equipment cost is relatively high. The above defects limit the study of microscopic imaging of the distribution of •OH on the electrode surface or the interface of catalytic materials. Therefore, it is urgent to develop an •OH detection technology with high sensitivity, real-time dynamic monitoring capabilities and spatial resolution characteristics to overcome the inherent defects of traditional methods. Summary of the invention

[0004] The present invention provides an in-situ analysis device and method for producing hydroxyl radicals by an electro-Fenton method, which solves the problems of the prior art that the reaction process cannot be dynamically monitored and the sensitivity is low.

[0005] In order to solve this technical problem, the present invention provides the following technical solution:

[0006] An in-situ analysis device for producing hydroxyl radicals by an electro-Fenton method, comprising:

[0007] Metal shielding shell, micrometer displacement slide, in-situ electrolytic cell, high-resolution camera, shockproof optical platform, electrochemical workstation, data analysis computer;

[0008] The shockproof optical platform is arranged on the bottom surface of the metal shielding shell, and the in-situ electrolytic cell, the micrometer displacement slide and the high-resolution camera for real-time observation of the in-situ electrolytic cell are arranged on the shockproof optical platform;

[0009] The micrometer displacement slide is provided with a first working electrode; the in-situ electrolytic cell is provided with a second working electrode;

[0010] The electrochemical workstation is electrically connected to the first working electrode and the second working electrode respectively, and is used for real-time acquisition of electrochemical signals;

[0011] The data analysis computer is electrically connected to the electrochemical workstation and is used for real-time analysis, processing and display of electrochemical data.

[0012] The data analysis computer is used to process electrochemical signals in real time; the electrochemical workstation is used to detect signals in real time; the optical anti-vibration platform is used to stabilize the electrode; the high-resolution camera is used to observe the relative position of the probe electrode and the substrate electrode; the micrometer displacement platform is used to control the position of the probe electrode in space relative to the substrate electrode in the X, Y, and Z axis directions; the shielding box reduces external interference and improves the accuracy of electrochemical testing;

[0013] In the in-situ analysis device of the present scheme, different potentials are applied to the second working electrode, and the response current signal of the first working electrode to the substance captured by the capture agent is measured, and the concentration of hydroxyl radicals generated under different potentials applied to the second working electrode is obtained by plotting the curve of the current of the first working electrode versus the potential.

[0014] Preferably, it also includes a counter electrode and a reference electrode; the counter electrode and the reference electrode are both connected to the in-situ electrolytic cell via a dedicated interface.

[0015] The four-electrode measurement system including a counter electrode and a reference electrode can accurately control the potential of the first working electrode and the second working electrode.

[0016] Preferably, the first working electrode is a gold electrode; the second working electrode is a carbon electrode; the counter electrode is a high-purity graphite rod; the reference electrode is an Ag / AgCl electrode;

[0017] The gold electrode is a gold wire with a diameter of 300 um and is obtained by glass packaging, and the carbon electrode has a diameter of 300 um.

[0018] This scheme also provides an in-situ analysis method for the production of hydroxyl radicals by the electro-Fenton method, which is performed using the above-mentioned in-situ analysis device and includes the following steps:

[0019] S1. Assembly and debugging of the electrode system: fix the first working electrode to the micrometer displacement slide, fix the second working electrode to the bottom of the in-situ electrolytic cell, accurately adjust the position of the first working electrode by the micrometer displacement slide, and observe with a high-resolution camera; turn on the data analysis computer and electrochemical workstation;

[0020] S2. Construction of reaction system: injecting electrolyte and reactants into the in-situ electrolytic cell, wherein the electrolyte is 0.1 M sodium sulfate solution; the reactants include 5 mM hydrogen peroxide and 10 mM 5,5-dimethyl-1-pyrroline-N-oxide DMPO;

[0021] S3, electrochemical test: applying different potentials to the second working electrode;

[0022] Cyclic voltammetry scanning is performed on the first working electrode, and the current signal of the first working electrode is collected in real time using an electrochemical workstation.

[0023] Preferably, after step S1, a system verification step is also included:

[0024] Generation-collection experiments were performed using 0.1 M potassium chloride and 0.1 mM hydroxymethylferrocene solution to verify the electrode spacing and system response characteristics.

[0025] Preferably, in step S1, the distance between the first working electrode and the second working electrode is adjusted to 50-100 μm.

[0026] Preferably, the scan rate on the first working electrode is 50 mVs -1 .

[0027] Preferably, the potential range of the first working electrode is -0.22V to 1.18V (vs. Ag / AgCl).

[0028] Preferably, the potential applied to the second working electrode is 0V to -0.6V (vs. Ag / AgCl).

[0029] Preferably, the potential applied to the second working electrode is 0 V (vs. Ag / AgCl), -0.2 V (vs. Ag / AgCl), -0.4 V (vs. Ag / AgCl), -0.6 V (vs. Ag / AgCl)

[0030] When the above method is working: the first working electrode and the second working electrode are respectively fixed by the above-mentioned micrometer displacement slide and the in-situ electrolytic cell, the micrometer displacement platform is moved in the x, y, and z axes, and observed by a high-resolution camera, the position of the first working electrode is adjusted so that the first working electrode is close to the second working electrode, the data analysis computer and the electrochemical workstation are turned on, and a generation and collection experiment is carried out using 0.1M potassium chloride and 0.1mM hydroxymethylferrocene solution, and the collection efficiency is 100%.

[0031] The 0.1 M potassium chloride and 0.1 mM hydroxymethylferrocene solutions were replaced, and 0.1 M sodium sulfate solution, 5 mM hydrogen peroxide and 10 mM 5,5-dimethyl-1-pyrroline-N-oxide were added to the in-situ electrolytic cell.

[0032] Set at 50 mV s -1 A cyclic voltammetry (CV) experiment was carried out with the first working electrode under a potential applied to the second working electrode. The catalyst on the second working electrode catalyzed the reduction of hydrogen peroxide to produce hydroxyl radicals, which were captured by the capture agent in the salt solution and collected by the first working electrode. The current signal value of the first working electrode collecting the species was a function of the potential applied to the second working electrode.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] When the detection device of the present invention is working, the purity requirement for the capture agent 5,5-dimethyl-1-pyrroline-N-oxide is not high, and the generally required solution purity is about 97%, which greatly saves the experimental cost.

[0035] The detection device of the present invention can detect in real time when working, and can detect the generation of hydroxyl free radicals in real time, and is suitable for dynamic process monitoring;

[0036] The detection device of the present invention has wide applicability and is suitable for a variety of electrode materials and catalytic systems. For example, in industrial wastewater treatment, the system can be used to monitor the hydroxyl radical generation efficiency of different electrode materials during the treatment process, thereby optimizing the treatment process; it can also be applied to scientific research experiments to provide a powerful tool for studying the reaction mechanism of hydroxyl radicals on the surfaces of different materials, thereby promoting scientific research and development in related fields.

[0037] The detection device of the present invention is easy to operate, has a small overall size, is easy to move, and is suitable for monitoring hydroxyl radical concentrations in a variety of complex environments. Its portable design allows researchers to easily bring it to different experimental scenarios, whether it is a fine experiment in the laboratory, on-site monitoring in the outdoor environment, or process control in industrial production. The device can be quickly put into use without tedious installation and debugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0039] Figure 1 It is an overall schematic diagram of the in-situ analysis device for producing hydroxyl radicals by the electro-Fenton method of the present invention;

[0040] Figure 2 A schematic diagram showing a collection efficiency of 100% in a hydroxymethylferrocene solution;

[0041] Figure 3 It is a partial schematic diagram of the in-situ analysis device for producing hydroxyl radicals by the electro-Fenton method of the present invention;

[0042] Figure 4 Schematic diagram of the collection experiment for hydroxyl radical generation;

[0043] Figure 5 collecting experimental cyclic voltammograms for the first working electrode for applying different potentials to the second working electrode;

[0044] The markings and corresponding component names in the attached figure are: 1. Metal shielding shell; 2. Micrometer displacement slide; 3. In-situ electrolytic cell; 4. High-resolution camera; 5. Shock-proof optical platform; 6. Electrochemical workstation; 7. Data analysis computer. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0046] The implementation method of this scheme includes an in-situ analysis device for generating hydroxyl radicals by an electro-Fenton method, comprising:

[0047] Metal shielding shell 1, micrometer displacement slide 2, in-situ electrolytic cell 3, high-resolution camera 4, shockproof optical platform 5, electrochemical workstation 6, data analysis computer 7;

[0048] The shockproof optical platform 5 is arranged on the bottom surface of the metal shielding shell 1, and the in-situ electrolytic cell 3, the micrometer displacement slide 2 and the high-resolution camera 4 for real-time observation of the in-situ electrolytic cell 3 are arranged on the shockproof optical platform 5;

[0049] The micrometer displacement slide 2 is provided with a first working electrode; the in-situ electrolytic cell 3 is provided with a second working electrode;

[0050] The electrochemical workstation 6 is electrically connected to the first working electrode and the second working electrode respectively, and is used for real-time acquisition of electrochemical signals;

[0051] The data analysis computer 7 is electrically connected to the electrochemical workstation 6 for real-time analysis, processing and display of electrochemical data.

[0052] As a preferred embodiment, it also includes a counter electrode and a reference electrode; the counter electrode and the reference electrode are both connected to the in-situ electrolytic cell 3 through a dedicated interface.

[0053] As a preferred embodiment, the first working electrode is a gold electrode; the second working electrode is a carbon electrode; the counter electrode is a high-purity graphite rod; the reference electrode is an Ag / AgCl reference electrode;

[0054] The implementation method of this scheme also includes an in-situ analysis method for generating hydroxyl radicals by the electro-Fenton method, which is performed using the above-mentioned in-situ analysis device and includes the following steps:

[0055] S1. Assembly and debugging of the electrode system: fix the first working electrode 1 to the micrometer displacement slide 2, and fix the second working electrode to the bottom of the in-situ electrolytic cell 3. Accurately adjust the position of the first working electrode by the micrometer displacement slide 2, and observe with a high-resolution camera 4; turn on the data analysis computer 7 and the electrochemical workstation 6; in the embodiment shown, in step S1, adjust the distance between the first working electrode and the second working electrode to 50-100 μm.

[0056] S2, reaction system construction: injecting electrolyte and reactants into the in-situ electrolytic cell 3, wherein the electrolyte is 0.1M sodium sulfate solution; the reactants include 5mM hydrogen peroxide and 10mM 5,5-dimethyl-1-pyrroline-N-oxide DMPO;

[0057] S3, electrochemical test: applying different potentials to the second working electrode;

[0058] Cyclic voltammetry scanning is performed on the first working electrode, and the current signal of the first working electrode is collected in real time using the electrochemical workstation 6. In the embodiment shown, the scanning rate on the first working electrode is 50 mVs -1 , the potential range of the first working electrode is -0.22V to 1.18V (vs.Ag / AgCl); the potential applied to the second working electrode is 0V to -0.6V (vs.Ag / AgCl), and by way of example but not limitation, the potential applied to the second working electrode is 0V (vs.Ag / AgCl), -0.2V (vs.Ag / AgCl), -0.4V (vs.Ag / AgCl) or -0.6V (vs.Ag / AgCl).

[0059] As a preferred embodiment, after step S1, a system verification step is also included:

[0060] Generation-collection experiments were performed using 0.1 M potassium chloride and 0.1 mM hydroxymethylferrocene solution to verify the electrode spacing and system response characteristics.

[0061] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0062] Example 1

[0063] like Figure 1 , Figure 3 As shown, the schematic diagram of the in-situ analysis device for producing hydroxyl radicals by the electro-Fenton method in this embodiment is composed of a metal shielding shell 1, a micrometer displacement slide 2, an in-situ electrolytic cell 3, a high-resolution camera 4, a shockproof optical platform 5, an electrochemical workstation 6, and a data analysis computer 7;

[0064] The shockproof optical platform 5 is arranged on the bottom surface of the metal shielding shell 1, and the shockproof optical platform 5 is provided with the in-situ electrolytic cell 3, the micrometer displacement slide 2 and the high-resolution camera 4 for real-time observation of the in-situ electrolytic cell 3; the micrometer displacement slide 2 is provided with a first working electrode; the in-situ electrolytic cell 3 is provided with a second working electrode; the electrochemical workstation 6 is electrically connected to the first working electrode and the second working electrode respectively, for real-time acquisition of electrochemical signals; the data analysis computer 7 is electrically connected to the electrochemical workstation 6, for real-time analysis, processing and display of electrochemical data; the in-situ analysis device also includes a counter electrode and a reference electrode; the counter electrode and the reference electrode are both connected to the in-situ electrolytic cell 3 through a dedicated interface; the first working electrode is a gold electrode; the second working electrode is a carbon electrode; the counter electrode adopts a high-purity graphite rod; the reference electrode adopts an Ag / AgCl reference electrode;

[0065] Example 2

[0066] like Figure 2 As shown, in this embodiment, the solution uses 0.1M potassium chloride and 0.1mM hydroxymethylferrocene solution, a high-purity graphite rod is used as a counter electrode, silver / silver chloride is used as a reference electrode, a gold electrode is used as a first working electrode, and a special carbon electrode is used as a second working electrode. The first working electrode and the second working electrode are linearly scanned, the starting potential is 0 V vs.Ag / AgCl, the ending potential is 0.5V vs.Ag / AgCl, the limiting diffusion current ratio of the first working electrode and the second working electrode is 1, and the collection efficiency is 100%. The purpose of this is to ensure the rationality of the experimental conditions and parameters at this time, and to ensure the accuracy and reliability of subsequent experiments.

[0067] Example 3

[0068] An in-situ analysis method for generating hydroxyl radicals by an electro-Fenton method is performed using the in-situ analysis device of the above-mentioned embodiment 1, comprising the following steps:

[0069] The first working electrode is fixed to the micrometer displacement slide 2, the second working electrode is fixed to the bottom of the in-situ electrolytic cell 3, the micrometer displacement platform 2 is moved in the x, y, and z axes, the position of the first working electrode is accurately adjusted by the micrometer displacement slide 2, so that the first working electrode approaches the second working electrode, and the high-resolution camera 4 is used for observation, and the distance between the first working electrode and the second working electrode is adjusted to 50-100 μm; the data analysis computer 7 and the electrochemical workstation 6 are turned on;

[0070] In the in-situ electrolytic cell 3, 0.1 M sodium sulfate solution, 5 mM hydrogen peroxide and 10 mM 5,5-dimethyl-1-pyrroline-N-oxide were added.

[0071] Different potentials were applied to the second working electrode, and the potentials applied to the second working electrode were 0 V (vs. Ag / AgCl), -0.2 V (vs. Ag / AgCl), -0.4 V (vs. Ag / AgCl), and -0.6 V (vs. Ag / AgCl).

[0072] Cyclic voltammetry was performed on the first working electrode at a scan rate of 50 mVs -1 , the potential range is -0.22V~1.18V (vs.Ag / AgCl);

[0073] The catalyst on the second working electrode catalyzes the reduction of hydrogen peroxide to generate hydroxyl radicals, which are captured by the capture agent in the salt solution and collected by the first working electrode; the current signal value of the first working electrode collecting the species is a function of the potential applied by the second working electrode, and the current signal of the first working electrode is collected in real time using the electrochemical workstation 6.

[0074] like Figure 4 The principle of this embodiment is shown in the figure. 5,5-Dimethyl-1-pyrroline-N-oxide (DMPO) was used as a spin trapping agent in the experiment. DMPO can react with hydroxyl radicals (•OH) to form a stable adduct [DMPO−OH]• with a long lifetime, which can be easily detected. During the diffusion time span of the first working electrode collection process, [DMPO−OH]• loses an electron to form [DMPO−OH]+ and generates a current signal.

[0075] Comparative Example 1

[0076] In this comparative example 1, a four-electrode measurement system is adopted, including a first working electrode, a second working electrode, a reference electrode (silver-silver chloride), and a counter electrode (high-purity graphite rod). Among them, the electrolyte is a solution composed of 0.1M sodium sulfate, 5mM hydrogen peroxide, and 0mM 5,5-dimethyl-1-pyrroline-N-oxide. The second working electrode adopts the chronoamperometry method, and the applied potential is 0, -0.2, -0.4, -0.6 V vs.Ag / AgCl. Hydrogen peroxide catalytically reduces to produce hydroxyl radicals at different applied potentials. The hydroxyl radicals are captured by 5,5-dimethyl-1-pyrroline-N-oxide in the salt solution to form an adduct [DMPO−OH]• with a longer life span, and are collected at the first working electrode. The first working electrode adopts cyclic voltammetry, and the potential range is set to -0.22 ~1.18 vs.Ag / AgCl.

[0077] like Figure 5 As shown, the signal generated by the first working electrode is 1 / 2=1.03 V waveform was only observed in the presence of DMPO. It was not observed in Comparative Example 1; the signal intensity also depends on the applied potential on the second working electrode.

[0078] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An in-situ analysis device for producing hydroxyl radicals by electro-Fenton method, characterized in that: include: Metal shielding shell (1), micrometer displacement slide (2), in-situ electrolytic cell (3), high-resolution camera (4), shockproof optical platform (5), electrochemical workstation (6), data analysis computer (7); The shockproof optical platform (5) is arranged on the bottom surface of the metal shielding shell (1), and the in-situ electrolytic cell (3), the micrometer displacement slide (2) and the high-resolution camera (4) are arranged on the shockproof optical platform (5); A first working electrode is provided on the micrometer displacement slide (2); a second working electrode is provided in the in-situ electrolytic cell (3); The electrochemical workstation (6) is electrically connected to the first working electrode and the second working electrode respectively, and is used for real-time acquisition of electrochemical signals; The data analysis computer (7) is electrically connected to the electrochemical workstation (6) and is used for real-time analysis, processing and display of electrochemical data.

2. The in-situ analysis device for producing hydroxyl radicals by the electro-Fenton method according to claim 1, characterized in that: It also includes a counter electrode and a reference electrode; the counter electrode and the reference electrode are both connected to the in-situ electrolytic cell (3) via a dedicated interface.

3. The in-situ analysis device for producing hydroxyl radicals by the electro-Fenton method according to claim 1, characterized in that: The first working electrode is a gold electrode; the second working electrode is a carbon electrode; the counter electrode is a high-purity graphite rod; and the reference electrode is an Ag / AgCl electrode.

4. An in-situ analysis method for the production of hydroxyl radicals by electro-Fenton method, characterized in that: The method is carried out using the in-situ analysis device according to any one of claims 1 to 3, comprising the following steps: S1. Assembly and debugging of the electrode system: fix the first working electrode to the micrometer displacement slide (2), fix the second working electrode to the bottom of the in-situ electrolytic cell (3), accurately adjust the position of the first working electrode by the micrometer displacement slide (2), and observe with a high-resolution camera (4); turn on the data analysis computer (7) and the electrochemical workstation (6); S2. Construction of reaction system: injecting electrolyte and reactants into the in-situ electrolytic cell (3), wherein the electrolyte is a 0.1 M sodium sulfate solution; the reactants include 5 mM hydrogen peroxide and 10 mM 5,5-dimethyl-1-pyrroline-N-oxide DMPO; S3. Electrochemical test: applying different potentials to the second working electrode; performing cyclic voltammetry scanning on the first working electrode, and using an electrochemical workstation (6) to collect the current signal of the first working electrode in real time.

5. The in-situ analysis method for producing hydroxyl radicals by the electro-Fenton method according to claim 4, characterized in that: After step S1, a system verification step is also included: Generation-collection experiments were performed using 0.1 M potassium chloride and 0.1 mM hydroxymethylferrocene solution to verify the electrode spacing and system response characteristics.

6. The in-situ analysis method for producing hydroxyl radicals by the electro-Fenton method according to claim 4, characterized in that: In step S1, the distance between the first working electrode and the second working electrode is adjusted to 50-100 μm.

7. The in-situ analysis method for producing hydroxyl radicals by the electro-Fenton method according to claim 4, characterized in that: The scan rate on the first working electrode was 50 mVs -1 .

8. The in-situ analysis method for producing hydroxyl radicals by the electro-Fenton method according to claim 4, characterized in that: The potential range of the first working electrode is -0.22V to 1.18V (vs. Ag / AgCl).

9. The in-situ analysis method for producing hydroxyl radicals by the electro-Fenton method according to claim 4, characterized in that: The potential applied to the second working electrode is 0V~-0.6V (vs.Ag / AgCl).

10. The in-situ analysis method according to claim 9, characterized in that: The potential applied to the second working electrode was 0 V (vs. Ag / AgCl), -0.2 V (vs. Ag / AgCl), -0.4 V (vs. Ag / AgCl), and -0.6 V (vs. Ag / AgCl).

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