Electrochemical electrode for detecting hydrogen peroxide concentration and detection device and method thereof

Abstract

The invention provides an electrochemical electrode for detecting hydrogen peroxide concentration and a detection device and method thereof. The device comprises a rotating electrode, a static electrode and a reference electrode, the rotating electrode comprises a driving motor, a rotating rod and a rotating body which are connected in sequence, a first current collector is arranged in the rotating body, and a detection electrode is embedded in the bottom of the rotating body; the static electrode comprises an insulating shell, a second current collector and a counter electrode, the second current collector is arranged in the insulating shell, and the counter electrode is embedded in the top of the insulating shell and is arranged right below the detection electrode in parallel. The invention also provides a hydrogen peroxide concentration detection device provided with the electrochemical electrode and a method for detecting the hydrogen peroxide concentration on the detection device. In the hydrogen peroxide concentration detection process, the hydrogen peroxide concentration on the surface of the detection electrode is kept relatively stable and is close to the concentration of the whole hydrogen peroxide solution, the detection result error is small, the reproducibility is good, the detection limit is low, the detection range is large, and the detection efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen peroxide concentration detection, and in particular to an electrochemical electrode for detecting hydrogen peroxide concentration and a detection device and method thereof. Background Art

[0002] Hydrogen peroxide, also known as hydrogen peroxide, has a chemical formula of H2O2 and is an important chemical product that is widely used in chemical synthesis, industrial papermaking, environmental governance, medical disinfection, etc. The concentration of hydrogen peroxide is usually determined by the method specified in GB / T 1616-2014 Industrial Hydrogen Peroxide. This determination method is the potassium permanganate (KMnO4) titration method, and its determination principle is: in an acidic medium, hydrogen peroxide and potassium permanganate undergo a redox reaction, and the content of hydrogen peroxide is calculated based on the consumption of potassium permanganate standard titration solution, that is, the concentration of hydrogen peroxide is obtained.

[0003] Potassium permanganate titration method for hydrogen peroxide concentration, because potassium permanganate reagent is unstable and usually contains impurities such as manganese dioxide, it is not possible to prepare a solution of accurate concentration by direct weighing. It is necessary to first use the standard substance sodium oxalate (Na2C2O4) to calibrate the concentration of potassium permanganate solution, and then use potassium permanganate solution to calibrate the concentration of hydrogen peroxide. The calibration process is relatively complicated and cumbersome, and the calibration conditions are relatively harsh. For example, when using the reference substance sodium oxalate solution to calibrate the concentration of potassium permanganate solution, the sodium oxalate solution needs to be heated to between 75 and 85°C; when the temperature is too low, the permanganate ions react slowly with the oxalate ions, and when the temperature is too high, the reference substance sodium oxalate will decompose; at the same time, the acidity of the solution will also affect the stability of the reference substance sodium oxalate and the calibrated substance potassium permanganate. Too high acidity will cause sodium oxalate to decompose, and too low acidity will cause potassium permanganate to decompose, making the calibrated potassium permanganate concentration inaccurate, which in turn affects the accuracy of the subsequent calibration of hydrogen peroxide concentration. Therefore, this potassium permanganate titration method for hydrogen peroxide concentration is usually only suitable for laboratory use, and it is difficult to meet the needs of rapid batch online continuous detection of hydrogen peroxide concentration in different occasions. In addition, the detection limit of this potassium permanganate titration method for hydrogen peroxide concentration is usually around 1 mg / L, which cannot meet the detection needs of lower concentration hydrogen peroxide.

[0004] At present, the prior art begins to use electrochemical methods to detect hydrogen peroxide concentration, and some electrodes for detecting hydrogen peroxide concentration have appeared. For example, Chinese patent CN117451801A discloses a hydrogen peroxide concentration detection electrode, which is a two-electrode system, including a working electrode and a counter electrode, wherein the working electrode is a disk electrode, and the counter electrode is a sheet electrode, relative to 100mm 2The diameter of the disc electrode is 0.5-5 mm. In the process of detecting the concentration of hydrogen peroxide, the working electrode is immersed in the electrochemical analysis cell and remains stationary. The time required for the current to reach a steady state is long, and the time to complete the detection and analysis is long. The detection efficiency is low, the detection limit of hydrogen peroxide is high, and the detection concentration range is small; moreover, the concentration of hydrogen peroxide on the surface of the working electrode is quite different from the concentration of the hydrogen peroxide solution itself, and the error of the detection result is large; in addition, the steady-state current reached by this working electrode in each test is different, and the reproducibility of the detection result is poor. Summary of the invention

[0005] The object of the present invention is to provide an electrochemical electrode for detecting hydrogen peroxide concentration and a detection device and method thereof, aiming to solve the problems in the prior art that the working electrode of the hydrogen peroxide concentration detection electrode is in a static state, resulting in low detection efficiency, high detection limit, small detection concentration range, large error in detection results and poor reproducibility.

[0006] In order to solve the above technical problems, the technical solution of the present invention is achieved as follows:

[0007] In one aspect, an electrochemical electrode for detecting hydrogen peroxide concentration of the present invention comprises a rotating electrode, a static electrode and a reference electrode; the rotating electrode comprises a driving motor, a rotating rod and a rotating body, the driving motor is connected to one end of the rotating rod, the other end of the rotating rod is connected to a first current collector, the first current collector is coaxially arranged inside the rotating body, the rotating body is an insulating cylinder, the bottom of the rotating body is inlaid with a detection electrode, the detection electrode is arranged in a cylindrical shape, the top surface of the detection electrode is in contact with the first current collector, the bottom surface of the detection electrode and the bottom surface of the rotating body are on the same horizontal plane and the center of the circle coincides; The stationary electrode comprises an insulating shell, a second current collector and a counter electrode, wherein the insulating shell comprises a first shell located at one side of the rotating electrode and a second shell located below the rotating electrode, the second current collector is arranged inside the insulating shell and extends from the first shell to the second shell, one end of the second current collector inside the second shell is connected to the counter electrode, the counter electrode is embedded in the top of the second shell and arranged in parallel directly below the detection electrode, and the top surface of the counter electrode is on the same horizontal plane as the top surface of the second shell; the reference electrode is arranged on the side of the rotating electrode away from the stationary electrode.

[0008] The electrochemical electrode for detecting hydrogen peroxide concentration of the present invention adopts a rotating electrode. The driving motor in the rotating electrode drives the rotating body and the detection electrode therein to rotate through a rotating rod. In the process of detecting the hydrogen peroxide concentration, the rotating detection electrode has a stirring effect on the hydrogen peroxide solution, so that the hydrogen peroxide concentration on the surface of the detection electrode remains relatively stable and close to the concentration of the entire hydrogen peroxide solution itself, avoiding the phenomenon that the concentration of the static detection electrode surface continues to decrease due to the consumption of hydrogen peroxide, greatly reducing the detection error and improving the accuracy of the detection result; moreover, the stirred hydrogen peroxide solution generates convection on the surface of the detection electrode, so that the diffusion layer of the detection electrode / hydrogen peroxide solution interface becomes thinner, the diffusion rate increases, the time for the detection current to reach a steady state is shortened, and the detection speed and detection efficiency are improved; at the same time, the stirred hydrogen peroxide solution reaches the same steady-state current when multiple detections are performed, and the detection result has good reproducibility. In addition, this rotating detection electrode can significantly enhance the mass transfer of hydrogen peroxide solution to the detection electrode surface, and obtain a higher detection current at the same hydrogen peroxide concentration, thereby improving the sensitivity of detecting hydrogen peroxide concentration, reducing the detection limit of hydrogen peroxide concentration, and increasing the detection range of hydrogen peroxide concentration.

[0009] In the electrochemical electrode for detecting the concentration of hydrogen peroxide of the present invention, the hydrogen peroxide solution undergoes oxidation or reduction reaction on the detection electrode. After applying the detection potential to the detection electrode, the current of the oxidation reaction or reduction reaction gradually reaches a steady state from a transient state, and the steady-state current is proportional to the concentration of hydrogen peroxide in the electrolyte (hydrogen peroxide solution). Therefore, the concentration of hydrogen peroxide can be determined according to the magnitude of the current of the hydrogen peroxide oxidation reaction or reduction reaction. This electrochemical electrode for detecting the concentration of hydrogen peroxide can be widely used for online or offline rapid detection or batch detection of hydrogen peroxide concentration in different process stages of the anthraquinone method for producing hydrogen peroxide, and can also be used in scenarios where the concentration of hydrogen peroxide needs to be monitored in industries such as papermaking, chemical synthesis, and water treatment.

[0010] As a preferred embodiment, the rotating rod is provided with an external thread, the first current collector is provided with an internal thread adapted to the external thread, and the rotating rod and the first current collector are adapted to be connected through the external thread and the internal thread. The rotating body is used as a whole in conjunction with the rotating rod; usually, a detection electrode of different materials or different diameters is arranged in each rotating body and is equipped with a first current collector. When the detection electrode needs to be replaced, the rotating body can be directly replaced; the rotating body of this arrangement is simple to connect to the rotating rod and is easy to replace, which can well meet the detection requirements of hydrogen peroxide concentration under different working conditions.

[0011] As a preferred embodiment, the first current collector is arranged in a cylindrical shape, and the cross-sectional area of ​​the first current collector is equal to the cross-sectional area of ​​the detection electrode. The material of the rotating body is an insulating material such as polyetheretherketone (PEKK) or polytetrafluoroethylene (PTFE). A through hole is provided inside the rotating body for installing the first current collector and the detection electrode. The first current collector and the detection electrode with the same diameter are adopted. The through holes inside the rotating body are consistent from top to bottom, which is convenient for opening holes and processing. The material of the first current collector is copper, silver or stainless steel, and the rotating rod is made of the same material as the first current collector. Normally, the upper end face of the first current collector is flush with the top end face (i.e., the top face) of the rotating body, and the lower end face of the first current collector is close to the top end face (i.e., the top face) of the detection electrode; this rotating body has a neat appearance and is easy to connect with the rotating rod, which improves the convenience of use.

[0012] As a preferred embodiment, the diameter of the detection electrode is 0.25 to 10 mm. The smaller the size of the detection electrode, the smaller the detection current can be obtained under the same detection potential, avoiding excessive detection current leading to violent decomposition of hydrogen peroxide and reducing the detection error of hydrogen peroxide concentration; the present invention can select detection electrodes of different sizes according to actual conditions to meet the detection requirements of hydrogen peroxide of different concentrations. The driving motor drives the rotating rod and the rotating body connected thereto and the detection electrode in the rotating body to rotate coaxially.

[0013] As a preferred embodiment, an insulating sleeve is provided between the rotating rod and the output shaft of the driving motor, a brush is provided on the outside of the rotating rod, one end of the brush is connected to the rotating rod, and the other end of the brush is provided with a first terminal. The first terminal is a terminal of the detection electrode, and the brush is used to conduct current between the rotating rod and the stationary first terminal. The detection electrode is connected to the working electrode of the potentiostat through the first current collector, the rotating rod, the brush and the first terminal, thereby achieving electrical conduction of the detection electrode. The insulating sleeve is provided at the connection between the rotating rod and the output shaft of the driving motor to prevent the current on the conductive rotating rod from being transmitted to the driving motor, thereby fully ensuring the safety of the electrochemical electrode.

[0014] As a preferred embodiment, the distance between the bottom surface of the detection electrode and the top surface of the counter electrode is 2 to 5 mm. The counter electrode is arranged in parallel directly below the detection electrode under the action of the insulating shell. The detection electrode and the counter electrode form an electrode pair. The distance between the bottom surface of the detection electrode and the top surface of the counter electrode is controlled to avoid short circuit between the detection electrode and the counter electrode. At the same time, it also avoids the detection potential being too large due to the large spacing between the detection electrode and the counter electrode, which causes the constant potential instrument to exceed the range.

[0015] As a preferred embodiment, the counter electrode is arranged in a cylindrical shape, the cross-sectional area of ​​the counter electrode is not less than the cross-sectional area of ​​the detection electrode, and the center line of the counter electrode is on the same vertical line as the center line of the detection electrode. Generally, the cross-sectional area of ​​the counter electrode is not less than the cross-sectional area of ​​the detection electrode, thereby reducing the polarization of the detection electrode, ensuring the accuracy of the detection potential applied to the detection electrode, and improving the accuracy of the detection.

[0016] As a preferred embodiment, the first shell is vertically arranged on one side of the second shell, the first shell is cylindrical, the second shell is disc-shaped, and the second current collector is L-shaped. The insulating shell is to fully protect the counter electrode and the second current collector connected thereto to ensure the safety of the electrical connection of the counter electrode immersed in the electrolyte. The insulating shell is made of polyetheretherketone (PEKK) or polytetrafluoroethylene (PTFE). The second current collector is usually a copper rod with a diameter of about 2 to 5 mm. The copper rod is L-shaped, and one end of the copper rod is welded to the bottom surface of the counter electrode, and the other end of the copper rod extends to the outside of the insulating shell, exposing about 5 to 20 mm to form a second terminal, which is the terminal of the counter electrode.

[0017] As a preferred embodiment, the horizontal distance between the surface of the reference electrode close to the rotating body and the surface of the rotating body close to the reference electrode is 1 to 5 mm. The reference electrode should be as close to the detection electrode as possible to reduce the voltage drop caused by the solution resistance between the detection electrode and the reference electrode, ensure the accuracy of the applied detection potential, and improve the accuracy of the detection; there is a rotating body between the reference electrode and the detection electrode, there is no risk of short circuit, and the reference electrode can be very close to the rotating body. The reference electrode is selected to match the salt ion type and acidity and alkalinity of the solution to be tested; the general selection principle is that if the solution to be tested is an acidic medium, a mercurous sulfate reference electrode is selected; if the solution to be tested is alkaline, a mercuric oxide reference electrode is selected; if the solution to be tested is neutral, a calomel or silver chloride reference electrode is selected.

[0018] As a preferred embodiment, the detection electrode is any one of a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode. The detection electrode is an inert electrode that does not participate in the electrochemical reaction itself and has no catalytic decomposition effect on hydrogen peroxide. The present invention uses a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode as the detection electrode. These detection electrodes have high oxygen evolution potential and a wider electrochemical potential window, which can reduce the detection limit of hydrogen peroxide, broaden the detection concentration range of hydrogen peroxide, and reduce the interference of the oxygen evolution reaction current signal.

[0019] As a preferred embodiment, the counter electrode is any one of a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode. Hydrogen peroxide undergoes a reduction reaction on the counter electrode. The present invention uses a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode as the counter electrode. These counter electrodes have a low hydrogen evolution potential and can electrochemically detect the concentration of hydrogen peroxide in a wider potential range, thereby reducing the detection limit of hydrogen peroxide, broadening the detection concentration range of hydrogen peroxide, and reducing the interference of the hydrogen evolution reaction current signal. The boron-doped diamond electrode is composed of a cylindrical substrate and a boron-doped diamond film. The material of the substrate is one of carbide-forming elements such as silicon, titanium, niobium, tungsten, molybdenum, and zirconium. The boron-doped diamond film is prepared on a cylindrical substrate by hot wire chemical vapor deposition; when a non-metallic substrate is used, the two bottom surfaces and side surfaces of the cylindrical substrate are all covered with a boron-doped diamond film; when a metal substrate is used, at least one bottom surface of the cylindrical substrate is covered with a boron-doped diamond film.

[0020] In another aspect, an electrochemical detection device for detecting hydrogen peroxide concentration of the present invention comprises a detection cell, a constant potential instrument, a resistivity tester, a data storage and processor, and a data display, wherein a detection solution is provided inside the detection cell, and the electrochemical electrode for detecting hydrogen peroxide concentration according to any one of the above items is suspended in the detection cell, and the bottoms of the rotating electrode, the static electrode, and the reference electrode are all immersed in the detection solution; the constant potential instrument is arranged on one side of the detection cell, and is respectively connected to the rotating electrode, the static electrode, and the reference electrode; the resistivity tester is suspended in the detection cell, and is used to detect the resistivity of the detection solution in the detection cell; the data storage and processor is electrically connected to the constant potential instrument, and is used to store and process the data measured by the constant potential instrument; the data display is connected to the data storage and processor, and is used to display the measured hydrogen peroxide concentration.

[0021] In the electrochemical detection device for detecting hydrogen peroxide concentration of the present invention, a three-system electrode with a rotating electrode is arranged in a detection cell. In the process of hydrogen peroxide concentration detection, the hydrogen peroxide concentration on the surface of the detection electrode of the three-system electrode remains relatively stable and close to the concentration of the entire hydrogen peroxide solution itself. The detection result has small error, good reproducibility, low detection limit, large detection range and high detection efficiency. The online rapid detection of hydrogen peroxide concentration is realized through electrochemical oxidation or reduction method, and the offline rapid detection of hydrogen peroxide concentration and batch rapid detection can also be performed. By improving the detection potential, rotation speed, effective working area and the like of the detection electrode, the detection limit of hydrogen peroxide concentration can be reduced to ng / L or μg / L. This electrochemical detection device for detecting hydrogen peroxide concentration is also equipped with a resistivity tester for measuring the resistivity of the hydrogen peroxide solution. In the subsequent hydrogen peroxide concentration detection process, the electrochemical detection signal is compensated by the solution resistance value, thereby eliminating the influence of the resistivity of the hydrogen peroxide solution on the electrochemical detection of hydrogen peroxide concentration, further improving the accuracy of hydrogen peroxide concentration detection, and is widely used for the detection of hydrogen peroxide concentration in different process stages of anthraquinone method for producing hydrogen peroxide. It can also be used in scenarios where hydrogen peroxide concentration needs to be monitored in industries such as papermaking, chemical synthesis, and water treatment.

[0022] As a preferred embodiment, a cover is provided on the top of the detection pool, a liquid inlet is provided on one side of the detection pool, and a liquid outlet is provided on the bottom of the detection pool. The detection pool is a cylindrical structure made of insulating engineering plastics. The setting of the liquid inlet and the liquid outlet can transport the detection solution to the inside of the detection pool through the liquid inlet, thereby realizing the detection of the hydrogen peroxide concentration of the detection solution; after the detection is completed, the detected solution is made to flow out of the detection pool through the liquid outlet, so that a new detection solution is input again through the liquid inlet, thereby completing the detection of the hydrogen peroxide concentration in different detection solutions, thereby improving the convenience of hydrogen peroxide concentration detection.

[0023] In another aspect, the present invention provides a method for detecting hydrogen peroxide concentration, which is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration described above, comprising the following steps: S1 preparation stage 1) determining the rotation speed V0 of the detection electrode and the drive motor and the potential E0 of the constant potential instrument according to the solution to be tested, and determining the counter electrode and the reference electrode; S2 preparing standard solution 2) preparing a series of concentrations of hydrogen peroxide standard solutions, adding potassium chloride, dissolving, and making the standard solution a saturated solution; S3 drawing a standard curve 3) placing one of the concentrations of the standard solution in the detection cell, the standard solution becomes the detection solution, starting the drive motor to make its rotation speed V0, starting the constant potential instrument to make its potential E0, measuring the steady-state current of the standard solution, and the data storage and processor recording the concentration of hydrogen peroxide and its corresponding steady-state current at this time; 4) according to the method described in step 3) Method, when the speed of the driving motor is V0, the steady-state current of the remaining standard solution when the potential of the constant potential instrument is E0 is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration under the potential E0; S4 detects the solution to be tested 5) The solution to be tested is placed in the detection tank, and the solution to be tested becomes the detection solution, and the resistivity meter is started to measure the resistivity R1 of the solution to be tested; 6) Start the driving motor, so that its speed is V1, V1=V0, start the constant potential instrument, so that its potential is E1, E1=E0, and measure the steady-state current I1 of the solution to be tested; 7) Adjust the potential of the constant potential instrument to E2, E2=E1+I1R1, and measure the steady-state current I2 of the solution to be tested again. The data storage and processor obtain the hydrogen peroxide concentration of the solution to be tested on the above standard curve according to the steady-state current I2 at this time, and display the hydrogen peroxide concentration of the solution to be tested through the data display.

[0024] The method for detecting the concentration of hydrogen peroxide of the present invention is a method for detecting the concentration of hydrogen peroxide by using the electrochemical detection device for detecting the concentration of hydrogen peroxide described above. The electrochemical detection device for detecting the concentration of hydrogen peroxide provides the detection electrodes, the rotation speed of the driving motor and the potential range of the constant potential meter required for the solution to be tested with different concentrations. The user determines the detection electrodes, the rotation speed V0 of the driving motor and the potential E0 of the constant potential meter to be used according to the actual situation; then, according to the concentration range of the solution to be tested, a series of hydrogen peroxide standard solutions with different concentrations are prepared, and a standard curve of current and hydrogen peroxide concentration is drawn; finally, the detection potential of the solution to be tested is corrected by using a resistivity meter to obtain the steady-state current of the solution to be tested, and the hydrogen peroxide concentration of the solution to be tested is obtained from the above standard curve. Hydrogen peroxide can undergo both oxidation and reduction reactions on the detection electrode of the electrochemical detection device for detecting hydrogen peroxide concentration of the present invention, and correspondingly, can undergo both reduction and oxidation reactions on the counter electrode; after the potentiostat applies an electric potential, the detection current gradually reaches a steady state from a transient state, and the steady-state current is proportional to the concentration of hydrogen peroxide in the electrolyte (detection solution), and accordingly, the concentration of hydrogen peroxide can be determined according to the size of the steady-state current of the detection solution. The detection method of hydrogen peroxide concentration of the present invention is easy to operate, has a small error, a high accuracy rate, a fast detection speed, good repeatability, high sensitivity, a low detection limit, and a large detection range.

[0025] When hydrogen peroxide undergoes an oxidation reaction on the detection electrode of the electrochemical detection device for detecting hydrogen peroxide concentration of the present invention, and correspondingly, a reduction reaction can occur on the counter electrode, the method for detecting hydrogen peroxide concentration of the present invention can detect a hydrogen peroxide solution with a hydrogen peroxide concentration of 1 ng / L to 10 g / L. When the hydrogen peroxide concentration is not less than 0.5 μg / L, the potential of the constant potential instrument is 0.5 to 1.5 V vs. SCE, preferably 1.0 V vs. SCE, where vs. SCE refers to the electrode potential relative to a saturated calomel electrode; when the hydrogen peroxide concentration is less than 0.5 μg / L, the potential of the constant potential instrument is 1.5 to 2.0 V vs. SCE, preferably 1.5 V vs.SCE; when the hydrogen peroxide concentration is not less than 50 ng / L, the speed of the driving motor is 400 to 5000 r / min, preferably 1000 r / min; when the hydrogen peroxide concentration is less than 50 ng / L, the speed of the driving motor is 5000 to 10000 r / min, preferably 10000 r / min. When hydrogen peroxide undergoes a reduction reaction on the detection electrode of the electrochemical detection device for detecting hydrogen peroxide concentration of the present invention, and correspondingly, an oxidation reaction can occur on the counter electrode, the method for detecting hydrogen peroxide concentration of the present invention can detect a hydrogen peroxide solution with a hydrogen peroxide concentration of 50 ng / L to 10 g / L. When the hydrogen peroxide concentration is not less than 5 μg / L, the potential of the constant potential instrument is -0.5 to -1.0 V vs. SCE, preferably -1.0 V vs. SCE; when the hydrogen peroxide concentration is less than 5 μg / L, the potential of the constant potential instrument is -1 to -1.5 V vs. SCE, preferably -1.5 V vs. SCE; when the hydrogen peroxide concentration is not less than 100 ng / L, the speed of the drive motor is 400 to 5000 r / min, preferably 1000 r / min; when the hydrogen peroxide concentration is less than 100 ng / L, the speed of the drive motor is 5000 to 10000 r / min, preferably 10000 r / min.

[0026] As a preferred embodiment, in step 1), the method for determining the rotation speed V0 of the detection electrode and the driving motor and the potential E0 of the constant potential instrument is as follows: placing the solution to be tested in the detection cell, the solution to be tested becomes the detection solution, selecting the detection electrode, starting the driving motor, and making its rotation speed V n , start the potentiostat to a potential of E n , measure the steady-state current I of the solution to be tested n ; If the steady-state current E of the solution to be tested n If the steady-state current E of the solution to be tested is not less than 100 nA, then the detection electrode, the speed of the drive motor and the potential of the constant potential instrument are appropriate. nIf the current is very weak, i.e., less than 100 nA, then increase the speed of the drive motor, and / or increase the potential of the potentiostat, and / or replace the detection electrode, and measure the steady-state current of the solution to be tested again until the steady-state current E of the solution to be tested is n Not less than 100nA; if the steady-state current E of the solution to be tested is n If the current is higher than the upper limit of the potentiostat, the speed of the driving motor is reduced, and / or the potential of the potentiostat is reduced, and / or the detection electrode is replaced, and the steady-state current of the solution to be tested is measured again until the steady-state current E of the solution to be tested is n It is smaller than the upper limit of the current of the potentiostat and not less than 100nA, thereby determining the detection electrode, the rotation speed V0 of the drive motor and the potential E0 of the potentiostat.

[0027] The electrochemical detection device for detecting the concentration of hydrogen peroxide of the present invention provides a reference range for selecting the detection electrode, the rotation speed of the driving motor and the potential of the constant potential instrument when detecting hydrogen peroxide of different concentrations; if the concentration range of hydrogen peroxide in the solution to be tested cannot be determined in the actual detection process, the detection electrode, the rotation speed V0 of the driving motor and the potential E0 of the constant potential instrument are determined according to the above method. At this time, according to the value of the steady-state current of the solution to be tested, the concentration range of the prepared standard solution can be determined, for example: a steady-state current of the order of nA is used to prepare a hydrogen peroxide standard solution of the order of ng / L, a steady-state current of the order of μA is used to prepare a hydrogen peroxide standard solution of the order of μg / L, a steady-state current of the order of mA is used to prepare a hydrogen peroxide standard solution of the order of mg / L, and a steady-state current of the order of A is used to prepare a hydrogen peroxide standard solution of the order of g / L.

[0028] Compared with the prior art, the present invention has the following beneficial effects: the electrochemical electrode for detecting hydrogen peroxide concentration of the present invention is a three-system electrode with a rotating electrode, in which a driving motor drives a rotating body and a detection electrode therein to rotate through a rotating rod; in the electrochemical detection device for detecting hydrogen peroxide concentration obtained thereby, during the hydrogen peroxide concentration detection process, the hydrogen peroxide concentration on the surface of the detection electrode remains relatively stable and is close to the concentration of the entire hydrogen peroxide solution itself, and under the cooperation of a resistivity tester, the detection error is greatly reduced; moreover, the hydrogen peroxide solution undergoes convection on the surface of the detection electrode, so that the diffusion layer at the interface of the detection electrode / hydrogen peroxide solution becomes thinner, the diffusion rate increases, the time for the detection current to reach a steady state is shortened, and the detection efficiency is improved; at the same time, when the hydrogen peroxide solution is detected multiple times, The steady-state currents achieved are all the same, and the detection results have good reproducibility; in addition, by increasing the detection potential, rotation speed, effective working area, etc. of the detection electrode, the detection limit of hydrogen peroxide concentration can be reduced to ng / L or μg / L; the method for detecting hydrogen peroxide concentration using this electrochemical detection device for detecting hydrogen peroxide concentration is easy to operate, has high accuracy, fast detection speed, good repeatability, high sensitivity, low detection limit, and a large detection range. The online rapid detection of hydrogen peroxide concentration is achieved through electrochemical oxidation or reduction method, and the offline rapid detection of hydrogen peroxide concentration and batch rapid detection can also be performed. It is widely used in the detection of hydrogen peroxide concentration in different process stages of anthraquinone production of hydrogen peroxide, and can also be used in scenarios where hydrogen peroxide concentration needs to be monitored in industries such as papermaking, chemical synthesis, and water treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 This is a schematic plan view of the structure of an embodiment of an electrochemical detection device for detecting hydrogen peroxide concentration provided by the present invention;

[0031] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure of the electrochemical electrode;

[0032] Figure 3 for Figure 2 A magnified view of the structure of the rotating electrode;

[0033] Figure 4 for Figure 3 Schematic diagram of the exploded structure of the rotating rod and the rotating body;

[0034] Figure 5 for Figure 2 A magnified view of the structure of the middle static electrode;

[0035] Figure 6 for Figure 2 Schematic diagram of the external structure of the detection cell;

[0036] Figure 7 This is a standard curve diagram obtained by detecting the concentration of hydrogen peroxide based on the electrochemical oxidation principle in Example 3 of the present invention;

[0037] Figure 8 This is a standard curve diagram obtained by detecting the concentration of hydrogen peroxide based on the electrochemical reduction principle in Example 3 of the present invention;

[0038] Fig. 9 This is a standard curve diagram obtained in Example 4 of the present invention;

[0039] Fig.10 This is a standard curve diagram obtained in Example 5 of the present invention;

[0040] Fig.11 This is a standard curve diagram obtained in Example 6 of the present invention;

[0041] Fig.12 This is a standard curve diagram obtained in Example 7 of the present invention;

[0042] Fig.13 This is a standard curve diagram obtained in Example 8 of the present invention;

[0043] In the figure: 100-electrochemical electrode; 200-detection cell; 300-potentiostat; 400-resistivity tester; 500-data storage and processor; 600-data display;

[0044] 110-rotating electrode; 120-static electrode; 130-reference electrode;

[0045] 111-driving motor; 112-rotating rod; 113-rotating body; 114-first current collector; 115-detection electrode; 116-brush; 117-first terminal;

[0046] 121 - insulating housing; 122 - second current collector; 123 - counter electrode; 124 - second terminal;

[0047] 210 - cover body; 220 - liquid inlet; 230 - liquid outlet. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Whenever possible, the various aspects and features described and shown in the specification can be applied separately, and these separate aspects can be the subject of divisional applications.

[0049] Embodiment 1

[0050] See attached Figure 2 , Attachment Figure 3 , Attachment Figure 4 and attached Figure 5The electrochemical electrode 100 for detecting the concentration of hydrogen peroxide of the present invention is a three-system electrode, including a rotating electrode 110, a static electrode 120 and a reference electrode 130; the rotating electrode 110 includes a driving motor 111, a rotating rod 112 and a rotating body 113, the driving motor 111 is connected to one end of the rotating rod 112, the other end of the rotating rod 112 is connected to a first current collector 114, the first current collector 114 is coaxially arranged inside the rotating body 113, the rotating body 113 is an insulating cylinder, the bottom of the rotating body 113 is inlaid with a detection electrode 115, the detection electrode 115 is arranged in a cylindrical shape, the top surface of the detection electrode 115 is in contact with the first current collector 114, and the bottom surface of the detection electrode 115 is in contact with the bottom surface of the rotating body 113. The static electrode 120 includes an insulating shell 121, a second current collector 122 and a counter electrode 123. The insulating shell 121 includes a first shell located on one side of the rotating electrode 110 and a second shell located below the rotating electrode 110. The second current collector 122 is arranged inside the insulating shell 121 and extends from the first shell to the second shell. One end of the second current collector 122 inside the second shell is connected to the counter electrode 123. The counter electrode 123 is embedded in the top of the second shell and is arranged in parallel directly below the detection electrode 115. The top surface of the counter electrode 123 and the top surface of the second shell are on the same horizontal plane. The reference electrode 130 is arranged on the side of the rotating electrode 110 away from the static electrode 120. In the process of detecting the concentration of hydrogen peroxide, the driving motor 111 in the rotating electrode 110 drives the rotating body 113 and the detection electrode 115 therein to rotate through the rotating rod 112. The rotating detection electrode 115 has a stirring effect on the hydrogen peroxide solution, so that the concentration of hydrogen peroxide on the surface of the detection electrode 115 remains relatively stable and close to the concentration of the entire hydrogen peroxide solution itself; the hydrogen peroxide solution is convected on the surface of the detection electrode, causing the diffusion layer at the interface of the detection electrode / hydrogen peroxide solution to become thinner and the diffusion rate to increase; in multiple detections, the steady-state currents reached are the same; therefore, the detection error of the electrochemical electrode for detecting the concentration of hydrogen peroxide is small, the accuracy is high, the detection speed is fast, and the repeatability is good. In addition, increasing the rotation speed of the detection electrode 115 can enhance the mass transfer of the hydrogen peroxide solution to the surface of the detection electrode 115, and obtain a higher detection current at the same hydrogen peroxide concentration, thereby improving the sensitivity of detecting the concentration of hydrogen peroxide, reducing the detection limit of the concentration of hydrogen peroxide, and increasing the detection range of the concentration of hydrogen peroxide.

[0051] See attached Figure 4In a preferred embodiment, the rotating rod 112 is provided with an external thread, and the first current collector 113 is provided with an internal thread adapted to the external thread, and the rotating rod 112 and the first current collector 113 are adapted to be connected by the external thread and the internal thread. The rotating body 113 is used as a whole in conjunction with the rotating rod 112; usually, a detection electrode 115 of different materials or different diameters is arranged in each rotating body 113 and is equipped with a first current collector 113; when the detection electrode 115 needs to be replaced, the rotating body 113 can be directly replaced. The rotating body 113 of this arrangement is simple to connect to the rotating rod 112 and is easy to replace, which can well meet the detection requirements of hydrogen peroxide concentration under different working conditions. Generally, the first current collector 113 is arranged in a cylindrical shape, and the cross-sectional area of ​​the first current collector 114 is equal to the cross-sectional area of ​​the detection electrode 115. The rotating body 113 is provided with through holes inside for installing the first current collector 114 and the detection electrode 115. The first current collector 114 and the detection electrode 115 have the same diameter, and the through holes inside the rotating body 113 are consistent from top to bottom, which is convenient for opening holes and processing. Usually, the upper end surface of the first current collector 114 is flush with the top surface of the rotating body 113, and the lower end surface of the first current collector 114 is close to the top surface of the detection electrode 115; this rotating body 113 has a neat appearance and is easy to connect with the rotating rod 112, which improves the convenience of use.

[0052] See attached Figure 4 In a preferred embodiment, the diameter of the detection electrode 115 is 0.25 to 10 mm. The smaller the size of the detection electrode 115, the smaller the detection current can be obtained under the same detection potential, avoiding excessive detection current leading to violent decomposition of hydrogen peroxide, and reducing the detection error of hydrogen peroxide concentration; the present invention can select detection electrodes 115 of different sizes according to actual conditions to meet the detection requirements of hydrogen peroxide of different concentrations. Specifically, the detection electrode 115 is any one of a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode. The detection electrode is an inert electrode that does not participate in the electrochemical reaction itself and has no catalytic decomposition effect on hydrogen peroxide. The present invention uses a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode as a detection electrode. These detection electrodes 115 have a high oxygen evolution potential and a wider electrochemical potential window, which can reduce the detection limit of hydrogen peroxide, broaden the detection concentration range of hydrogen peroxide, and reduce the interference of the oxygen evolution reaction current signal.

[0053] See attached Figure 3 , Attachment Figure 4 and attached Figure 5In a preferred embodiment, an insulating sleeve is provided between the rotating rod 112 and the output shaft of the driving motor 111. The insulating sleeve is provided at the connection between the rotating rod 112 and the output shaft of the driving motor 111 to prevent the current on the conductive rotating rod 112 from being transmitted to the driving motor 111, thereby fully ensuring the safety of the electrochemical electrode. In addition, a brush 116 is provided on the outside of the rotating rod 112, one end of the brush 116 is connected to the rotating rod 112, and the other end of the brush 116 is provided with a first terminal 117; the first terminal 117 is the terminal of the detection electrode 115, and the brush 116 is used to conduct current between the rotating rod 112 and the stationary first terminal 117. The detection electrode 115 realizes electrical conduction of the detection electrode 115 through the first current collector 114, the rotating rod 112, the brush 116 and the first terminal 117. Usually, the distance between the bottom surface of the detection electrode 115 and the top surface of the counter electrode 123 is 2 to 5 mm. The counter electrode 123 is arranged in parallel under the detection electrode 115 under the action of the insulating shell 121. The detection electrode 115 and the counter electrode 123 form an electrode pair, which controls the distance between the bottom surface of the detection electrode 115 and the top surface of the counter electrode 123 to avoid a short circuit between the detection electrode 115 and the counter electrode 123. At the same time, it also avoids the detection electrode 115 and the counter electrode 123 from being too large, resulting in excessive detection potential.

[0054] See attached Figure 3 and attached Figure 5In a preferred embodiment, the counter electrode 123 is arranged in a cylindrical shape, the cross-sectional area of ​​the counter electrode 123 is not less than the cross-sectional area of ​​the detection electrode 115, and the center line of the counter electrode 123 and the center line of the detection electrode 115 are on the same vertical line. Normally, the cross-sectional area of ​​the counter electrode 123 is not less than the cross-sectional area of ​​the detection electrode 115, thereby reducing the polarization of the detection electrode 115, ensuring the accuracy of the detection potential applied to the detection electrode 115, and improving the accuracy of the detection. Preferably, the first shell is vertically arranged on one side of the second shell, the first shell is arranged in a cylindrical shape, the second shell is arranged in a disc shape, and the second current collector 122 is arranged in an L shape. The insulating shell 121 is to fully protect the counter electrode 123 and the second current collector 122 connected thereto, so as to ensure the safety of the electrical connection of the counter electrode 123 immersed in the electrolyte (detection solution). Typically, one end of the second current collector 122 is welded to the bottom surface of the counter electrode 123, and the other end of the second current collector 122 extends to the outside of the insulating housing 111, exposed about 5 to 20 mm, to form a second terminal 124, which is a terminal of the counter electrode 123. Specifically, the counter electrode 123 is any one of a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode. Hydrogen peroxide undergoes a reduction reaction on the counter electrode 123. The lead dioxide electrode, the tin dioxide electrode, and the boron-doped diamond electrode are used as the counter electrode 123, which can reduce the hydrogen evolution potential of the counter electrode 123, and perform electrochemical detection of the concentration of hydrogen peroxide in a wider potential range, thereby reducing the detection limit of hydrogen peroxide, broadening the detection concentration range of hydrogen peroxide, and reducing the interference of the hydrogen evolution reaction current signal. The boron-doped diamond electrode is composed of a cylindrical substrate and a boron-doped diamond film. The substrate is made of one of the carbide-forming elements such as silicon, titanium, niobium, tungsten, molybdenum, zirconium, etc. The boron-doped diamond film is prepared on the cylindrical substrate by hot wire chemical vapor deposition. When a non-metallic substrate is used, the two bottom surfaces and side surfaces of the cylindrical substrate are all covered with the boron-doped diamond film. When a metal substrate is used, at least one bottom surface of the cylindrical substrate is covered with the boron-doped diamond film.

[0055] See attached Figure 2In a preferred embodiment, the horizontal distance between the surface of the reference electrode 130 close to the rotating body 113 and the surface of the rotating body 113 close to the reference electrode 130 is 1 to 5 mm. The reference electrode 130 should be as close to the detection electrode 115 as possible to reduce the voltage drop caused by the solution resistance between the detection electrode 115 and the reference electrode 130, ensure the accuracy of the applied detection potential, and improve the accuracy of the detection; there is a rotating body 113 between the reference electrode 130 and the detection electrode 115, there is no risk of short circuit, and the reference electrode 130 can be very close to the rotating body 113. Usually, the reference electrode 130 is selected to match the salt ion type and acidity and alkalinity of the solution to be tested; the general selection principle is that if the solution to be tested is an acidic medium, a mercurous sulfate reference electrode 130 is selected; if the solution to be tested is alkaline, a mercuric oxide reference electrode 130 is selected; if the solution to be tested is neutral, a calomel or silver chloride reference electrode 130 is selected.

[0056] Embodiment 2

[0057] See attached Figure 1 , Attachment Figure 2 , Attachment Figure 3 , Attachment Figure 4 , Attachment Figure 5 and attached Figure 6 The present invention provides an electrochemical detection device for detecting hydrogen peroxide concentration, comprising a detection cell 200, a constant potential instrument 300, a resistivity tester 400, a data storage and processor 500 and a data display 600; a detection solution is provided inside the detection cell 200, and the electrochemical electrode 100 for detecting hydrogen peroxide concentration described in the first embodiment is also suspended in the detection cell 200, and the electrochemical electrode 100 is a three-system electrode, comprising a rotating electrode 110, a static electrode 120 and a reference electrode 130, wherein the rotating electrode 110, the static electrode 120 and the reference electrode 130 are The bottom of the detection cell 200 is immersed in the detection solution; the constant potential instrument 300 is arranged on one side of the detection cell 200, and is respectively connected to the rotating electrode 110, the static electrode 120 and the reference electrode 130; the resistivity tester 400 is suspended in the detection cell 200, and is used to detect the resistivity of the detection solution in the detection cell 200; the data storage and processor 500 is electrically connected to the constant potential instrument 300, and is used to store and process the data measured by the constant potential instrument 300; the data display 600 is connected to the data storage and processor 500, and is used to display the measured hydrogen peroxide concentration.

[0058] In the electrochemical detection device for detecting hydrogen peroxide concentration of the present invention, a three-system electrode with a rotating electrode 110 is arranged in the detection cell 200. In the process of detecting hydrogen peroxide concentration, the hydrogen peroxide solution undergoes oxidation or reduction reaction at the anode (detection electrode 115) and reduction or oxidation reaction at the cathode (counter electrode 123). After applying the detection potential to the detection electrode 115, the current of the oxidation reaction or reduction reaction on the detection electrode 115 gradually changes from a transient state to a steady state, and the steady-state current is proportional to the concentration of hydrogen peroxide in the electrolyte (hydrogen peroxide solution). Therefore, the concentration of hydrogen peroxide can be determined according to the magnitude of the current of the hydrogen peroxide oxidation reaction or reduction reaction, and the online rapid detection of the hydrogen peroxide concentration is realized. The offline rapid detection of the hydrogen peroxide concentration and the batch rapid detection can also be performed. By improving the detection potential, rotation speed, effective working area, etc. of the detection electrode, the detection limit of the hydrogen peroxide concentration can be reduced to ng / L or μg / L. This electrochemical detection device for detecting hydrogen peroxide concentration is also equipped with a resistivity tester 400 for measuring the resistivity of the hydrogen peroxide solution, and in the subsequent hydrogen peroxide concentration detection process, the electrochemical detection signal is compensated by the solution resistance value, thereby eliminating the influence of the resistivity of the hydrogen peroxide solution on the electrochemical detection of hydrogen peroxide concentration, further improving the accuracy of hydrogen peroxide concentration detection, and is widely used for the detection of hydrogen peroxide concentration in different process stages of anthraquinone method production of hydrogen peroxide, and can also be used in scenarios where hydrogen peroxide concentration needs to be monitored in industries such as papermaking, chemical synthesis, and water treatment.

[0059] See attached Figure 2 and attached Figure 6 In a preferred embodiment, a cover 210 is provided on the top of the detection pool 200, a liquid inlet 220 is provided on one side of the detection pool 200, and a liquid outlet 230 is provided on the bottom of the detection pool 200. The detection pool 200 is a cylindrical structure, and the material is insulating engineering plastic. The arrangement of the liquid inlet 220 and the liquid outlet 230 can transport the detection solution to the inside of the detection pool 200 through the liquid inlet 220, thereby realizing the detection of the concentration of hydrogen peroxide in the detection solution; after the detection is completed, the detected solution flows out of the detection pool 200 through the liquid outlet 230, so that a new detection solution is input again through the liquid inlet 220, thereby completing the detection of the concentration of hydrogen peroxide in different detection solutions, and improving the convenience of hydrogen peroxide concentration detection.

[0060] Embodiment 3

[0061] 3.1 Detection test

[0062] A method for detecting hydrogen peroxide concentration of the present invention is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration of the second embodiment, and the hydrogen peroxide concentration is detected based on the electrochemical oxidation principle, comprising the following steps:

[0063] S1 Preparation

[0064] 1) It is known that the pH value of the solution to be tested is about 7.0, the concentration of hydrogen peroxide is 5-20 μg / L, a cylindrical boron-doped diamond electrode with a diameter of 10 mm is selected as the detection electrode, the speed V0 of the drive motor is selected to be 1000 r / min, the potential E0 of the potentiostat is selected to be 1.0 V vs. SCE, and a cylindrical boron-doped diamond electrode with a diameter of 12 mm is selected as the counter electrode, and a saturated calomel electrode is selected as the reference electrode;

[0065] S2 Preparation of standard solution

[0066] 2) prepare a series of hydrogen peroxide standard solutions with concentrations of 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L, 30 μg / L, 40 μg / L, and 50 μg / L, respectively, and add potassium chloride to dissolve to make the standard solution a saturated solution;

[0067] S3 draws the standard curve

[0068] 3) introducing one of the standard solutions of one concentration into the detection cell from the liquid inlet of the detection cell, so that the standard solution fills the detection cell and the standard solution becomes the detection solution; starting the drive motor to make its rotation speed 1000r / min, at this time, the rotation speed of the detection electrode is also 1000r / min; starting the constant potential instrument to make its potential 1.0V vs.SCE, at this time, the detection potential of the detection electrode is 1.0V vs.SCE, after the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time, after the steady-state current measurement is completed, the detection solution in the detection cell is discharged from the liquid outlet;

[0069] 4) According to the method described in step 3), at a driving motor speed of 1000 r / min, the steady-state current of the remaining standard solution when the potential of the potentiostat is 1.0 V vs. SCE is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration at a potential of 1.0 V vs. SCE ... Figure 7 It can be seen that the equation of the standard curve at this time is: y = 0.2111x + 0.0087, R 2 =1;

[0070] S4 detects the test solution

[0071] 5) The solution to be tested is input into the detection cell from the liquid inlet of the detection cell, and the solution to be tested becomes the detection solution. The resistivity meter is started, and the resistivity of the solution to be tested is measured to be R1=3.5Ω / cm. After calculation, the corresponding resistance is 3.5Ω / cm×0.3cm=1.05Ω;

[0072] 6) Start the driving motor and set its speed V1 to 1000 r / min. At this time, the speed of the detection electrode is also 1000 r / min. Start the constant potential instrument and set its potential to 1.0 V vs. SCE. At this time, the detection potential of the detection electrode is 1.0 V vs. SCE. The steady-state current I1 of the solution to be tested is measured to be 2.109 μA.

[0073] 7) Adjust the potential of the potentiostat to E2 = 1.0 + 2.109 × 10 -6 ×1.05=1.000V vs.SCE, and the steady-state current I2=2.110μA of the solution to be tested is measured again. The data storage and processor store the data in the adjacent Figure 7 On the standard curve shown, the hydrogen peroxide concentration of the solution to be tested is obtained to be 9.954 μg / L, and the hydrogen peroxide concentration of the solution to be tested is displayed by a data display.

[0074] This is a method for detecting the concentration of hydrogen peroxide based on the principle of electrochemical oxidation. Therefore, the method for detecting the concentration of hydrogen peroxide based on the principle of electrochemical oxidation of the present invention can accurately measure the concentration of hydrogen peroxide.

[0075] 3.2 Repeatability test

[0076] According to the method of step 5), step 6) and step 7), the solution to be tested is again input into the detection cell from the liquid inlet of the detection cell, the resistivity meter, the drive motor and the constant potentiostat are respectively started, the steady-state current of the solution to be tested is measured, and the hydrogen peroxide concentration of the solution to be tested displayed on the data display is recorded. Repeat once. The test results of 3.1 and 3.2 are listed in Table 1.

[0077] Table 1 Statistical table of multiple measurements of hydrogen peroxide concentration in the test solution

[0078] Number of detections Steady state current (μA) Hydrogen peroxide concentration (μg / L) first 2.110 9.954 Second time 2.109 9.949 The third time 2.109 9.949 average value 2.106 9.951 Standard Deviation 0.001 0.003 Coefficient of variation (%) 0.03 0.03

[0079] As can be seen from Table 1, when the hydrogen peroxide concentration detection method of the present invention repeatedly determines the concentration of hydrogen peroxide in the test solution three times, the steady-state current is 2.110, 2.109 and 2.109 μA respectively, the average value of the steady-state current is 2.106 μA, the standard deviation is 0.001, and the coefficient of variation is 0.03%; therefore, the steady-state current has good repeatability. At the same time, the measured hydrogen peroxide concentrations are 9.954, 9.949 and 9.949 μg / L respectively, the average value of the hydrogen peroxide concentration is 9.951 μg / L, the standard deviation is 0.003, and the coefficient of variation is 0.03%; therefore, the measured hydrogen peroxide concentration has good repeatability. Therefore, the hydrogen peroxide concentration measured by the method for detecting the hydrogen peroxide concentration based on the electrochemical oxidation principle of the present invention has good repeatability.

[0080] 3.3 Variation test

[0081] On the basis of the test in 3.1, the potential E0 of the potentiostat was set to -1.0 V vs. SCE, and other conditions remained unchanged, so as to detect the concentration of hydrogen peroxide based on the electrochemical reduction principle;

[0082] By the attached Figure 8 It can be seen that at this time, the equation of the standard curve of current and hydrogen peroxide concentration is: y = -0.0971x-0.004, R 2 =1;

[0083] In this process, the resistivity of the solution to be tested measured by the resistivity meter is R1 = 3.5Ω / cm, and the steady-state current of the solution to be tested measured by the constant potential meter is -0.970μA; the correction potential of the constant potential meter is E2 = -1.0-0.970×10 -6 ×1.05=-1.000V vs.SCE, the final steady-state current of the test solution was -0.971μA, and the corresponding hydrogen peroxide concentration was 9.959μg / L; the measurement was repeated twice, and the test results are listed in Table 2.

[0084] Table 2 Statistical table of the concentration of hydrogen peroxide in the test solution determined by electrochemical reduction method

[0085] Number of detections Steady state current (μA) Hydrogen peroxide concentration (μg / L) first -0.971 9.959 Second time -0.970 9.949 The third time -0.971 9.959 average value -0.971 9.956 Standard Deviation 0.001 0.006 Coefficient of variation (%) 0.06 0.06

[0086] As can be seen from Table 2, the present invention can also detect the concentration of hydrogen peroxide based on the electrochemical reduction principle. When the concentration of hydrogen peroxide is detected based on the electrochemical reduction principle, in the process of repeating the determination of the concentration of hydrogen peroxide in the solution to be tested three times, the steady-state current is -0.971, -0.970 and -0.971 μA, respectively, the average value of the steady-state current is -0.971 μA, the standard deviation is 0.001, and the coefficient of variation is 0.06%; therefore, the repeatability of the steady-state current is good. At the same time, the measured hydrogen peroxide concentrations are 9.959, 9.949 and 9.959 μg / L, respectively, the average value of the hydrogen peroxide concentration is 9.956 μg / L, the standard deviation is 0.006, and the coefficient of variation is 0.06%. Therefore, the hydrogen peroxide concentration measured by the method for detecting the concentration of hydrogen peroxide based on the electrochemical reduction principle of the present invention has good repeatability. Moreover, the results obtained by the detection method of the concentration of hydrogen peroxide of the present invention based on the electrochemical oxidation principle and the electrochemical reduction principle have good consistency.

[0087] 3.4 Comparative test

[0088] A method for statically detecting hydrogen peroxide concentration comprises the following steps:

[0089] S1 Preparation

[0090] 1) Using the test solution of 3.1, a cylindrical boron-doped diamond electrode with a diameter of 10 mm was selected as the detection electrode, a cylindrical boron-doped diamond electrode with a diameter of 12 mm was selected as the counter electrode, and a saturated calomel electrode was selected as the reference electrode;

[0091] S2 detects the solution to be tested

[0092] 2) Using the detection cell used in 3.1, input the test solution into the detection cell from the liquid inlet of the detection cell, so that the test solution fills the detection cell; do not start the resistivity meter and the drive motor, so that the detection electrode remains stationary; start the constant potential instrument, so that its potential is 1.0V vs.SCE, and the detection potential of the detection electrode is 1.0V vs.SCE. After the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time. After the steady-state current measurement is completed, the test solution in the detection cell is discharged from the liquid outlet;

[0093] 3) According to the method described in step 2), the test solution is again input into the detection cell from the liquid inlet of the detection cell. The resistivity meter and the drive motor are not started. Only the constant potential instrument is started to make its potential 1.0V vs. SCE. The steady-state current of the test solution is recorded. This is repeated twice. The test results are listed in Table 3.

[0094] Table 3 Statistical table of the results of hydrogen peroxide concentration in the test solution measured by the detection electrode when it is stationary

[0095] Number of detections Steady state current (μA) first 0.785 Second time 1.086 The third time 0.663 average value 0.845 Standard Deviation 0.218 Coefficient of variation (%) 25.78

[0096] It can be seen from Table 3 that when the stationary detection electrode detects the concentration of hydrogen peroxide in the test solution, the steady-state currents are 0.785, 1.086 and 0.663 μA respectively, the average value of these steady-state currents is 0.845 μA, the standard deviation is 0.218, and the coefficient of variation is 25.78%; therefore, the reproducibility of the steady-state current of the stationary detection electrode when detecting the concentration of hydrogen peroxide in the test solution is poor.

[0097] Embodiment 4

[0098] A method for detecting hydrogen peroxide concentration of the present invention is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration of the second embodiment, and the hydrogen peroxide concentration is detected based on the electrochemical oxidation principle, comprising the following steps:

[0099] S1 Preparation

[0100] 1) It is known that the pH value of the solution to be tested is about 7.0, the concentration of hydrogen peroxide is about 0.5-2 μg / L, a cylindrical boron-doped diamond electrode with a diameter of 10 mm is selected as the detection electrode, the speed V0 of the drive motor is selected to be 1000 r / min, the potential E0 of the potentiostat is selected to be 1.0 V vs. SCE, and a cylindrical boron-doped diamond electrode with a diameter of 12 mm is selected as the counter electrode, and a saturated calomel electrode is selected as the reference electrode;

[0101] S2 Preparation of standard solution

[0102] 2) prepare a series of hydrogen peroxide standard solutions with concentrations of 0.1 μg / L, 0.5 μg / L, 1 μg / L, 2 μg / L, 3 μg / L, 5 μg / L, and 10 μg / L, respectively, and add potassium chloride to dissolve to make the standard solution a saturated solution;

[0103] S3 draws the standard curve

[0104] 3) introducing one of the standard solutions of one concentration into the detection cell from the liquid inlet of the detection cell, so that the standard solution fills the detection cell and the standard solution becomes the detection solution; starting the drive motor to make its rotation speed 1000r / min, at this time, the rotation speed of the detection electrode is also 1000r / min; starting the constant potential instrument to make its potential 1.0V vs.SCE, at this time, the detection potential of the detection electrode is 1.0V vs.SCE, after the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time, after the steady-state current measurement is completed, the detection solution in the detection cell is discharged from the liquid outlet;

[0105] 4) According to the method described in step 3), at a driving motor speed of 1000 r / min, the steady-state current of the remaining standard solution when the potential of the potentiostat is 1.0 V vs. SCE is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration at a potential of 1.0 V vs. SCE ... Fig. 9 It can be seen that the equation of the standard curve at this time is: y = 1.3175x + 0.0365, R 2 =0.9999;

[0106] S4 detects the test solution

[0107] 5) The solution to be tested is input into the detection cell from the liquid inlet of the detection cell, and the solution to be tested becomes the detection solution. The resistivity meter is started, and the resistivity of the solution to be tested is measured to be R1=3.5Ω / cm. After calculation, the corresponding resistance is 3.5Ω / cm×0.3cm=1.05Ω;

[0108] 6) Start the driving motor and set its speed V1 to 1000 r / min. At this time, the speed of the detection electrode is also 1000 r / min. Start the constant potential instrument and set its potential to 1.0 V vs. SCE. At this time, the detection potential of the detection electrode is 1.0 V vs. SCE. The steady-state current I1 of the solution to be tested is measured to be 1.011 μA.

[0109] 7) Adjust the potential of the potentiostat to E2 = 1.0 + 1.011 × 10 -6 ×1.05=1.000V vs.SCE, and the steady-state current I2=1.012μA of the solution to be tested is measured again. The data storage and processor store the data in the adjacent Fig. 9 On the standard curve shown, the hydrogen peroxide concentration of the test solution is obtained to be 0.740 μg / L, and the hydrogen peroxide concentration of the test solution is displayed by a data display.

[0110] Embodiment 5

[0111] A method for detecting hydrogen peroxide concentration of the present invention is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration of the second embodiment, and the hydrogen peroxide concentration is detected based on the electrochemical oxidation principle, comprising the following steps:

[0112] S1 Preparation

[0113] 1) It is known that the pH value of the solution to be tested is about 7.0, the concentration of hydrogen peroxide is about 0.03-0.3 μg / L, a cylindrical boron-doped diamond electrode with a diameter of 10 mm is selected as the detection electrode, the speed V0 of the drive motor is selected to be 1000 r / min, the potential E0 of the potentiostat is selected to be 1.5 V vs. SCE, and a cylindrical boron-doped diamond electrode with a diameter of 12 mm is selected as the counter electrode, and a saturated calomel electrode is selected as the reference electrode;

[0114] S2 Preparation of standard solution

[0115] 2) prepare a series of hydrogen peroxide standard solutions with concentrations of 0.01 μg / L, 0.03 μg / L, 0.05 μg / L, 0.1 μg / L, 0.3 μg / L, 0.5 μg / L, and 1 μg / L, respectively, and add potassium chloride to dissolve to make the standard solution a saturated solution;

[0116] S3 draws the standard curve

[0117] 3) introducing one of the standard solutions of one concentration into the detection cell from the liquid inlet of the detection cell, so that the standard solution fills the detection cell and the standard solution becomes the detection solution; starting the drive motor to make its rotation speed 1000r / min, at this time, the rotation speed of the detection electrode is also 1000r / min; starting the constant potential instrument to make its potential 1.5V vs.SCE, at this time, the detection potential of the detection electrode is 1.5V vs.SCE, after the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time, after the steady-state current measurement is completed, the detection solution in the detection cell is discharged from the liquid outlet;

[0118] 4) According to the method described in step 3), at a driving motor speed of 1000 r / min, the steady-state current of the remaining standard solution when the potential of the potentiostat is 1.5 V vs. SCE is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration at a potential of 1.5 V vs. SCE ... Fig.10 It can be seen that the equation of the standard curve at this time is: y = 7.3992x + 0.0021, R 2 =1;

[0119] S4 detects the test solution

[0120] 5) The solution to be tested is input into the detection cell from the liquid inlet of the detection cell, and the solution to be tested becomes the detection solution. The resistivity meter is started, and the resistivity of the solution to be tested is measured to be R1=3.5Ω / cm. After calculation, the corresponding resistance is 3.5Ω / cm×0.3cm=1.05Ω;

[0121] 6) Start the driving motor and set its speed V1 to 1000 r / min. At this time, the speed of the detection electrode is also 1000 r / min. Start the constant potential instrument and set its potential to 1.5 V vs. SCE. At this time, the detection potential of the detection electrode is 1.5 V vs. SCE. The steady-state current I1 of the solution to be tested is measured to be 0.371 μA.

[0122] 7) Adjust the potential of the potentiostat to E2 = 1.5 + 0.371 × 10 -6 ×1.05=1.500V vs.SCE, and the steady-state current I2=0.371μA of the solution to be tested is measured again. The data storage and processor store the data in the adjacent Fig.10 On the standard curve shown, the hydrogen peroxide concentration of the test solution is obtained to be 0.0499 μg / L, and the hydrogen peroxide concentration of the test solution is displayed by a data display.

[0123] Embodiment 6

[0124] A method for detecting hydrogen peroxide concentration of the present invention is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration of the second embodiment, and the hydrogen peroxide concentration is detected based on the electrochemical oxidation principle, comprising the following steps:

[0125] S1 Preparation

[0126] 1) According to the pH value of the solution to be tested being about 7.0, the solution to be tested is placed in a detection cell, the solution to be tested becomes a detection solution, a cylindrical boron-doped diamond electrode with a diameter of 10 mm is selected as a detection electrode, a driving motor is started to rotate at a speed of 10000 r / min, a constant potential instrument is started to make its potential 1.5 V vs. SCE, and a steady-state current of the solution to be tested is measured to be 500 nA; a cylindrical boron-doped diamond electrode with a diameter of 12 mm is selected as a counter electrode, and a saturated calomel electrode is selected as a reference electrode;

[0127] S2 Preparation of standard solution

[0128] 2) prepare a series of hydrogen peroxide standard solutions with concentrations of 0.1 ng / L, 0.3 ng / L, 0.5 ng / L, 1 ng / L, 2 ng / L, 3 ng / L, and 5 ng / L, respectively, and add potassium chloride to dissolve to make the standard solution a saturated solution;

[0129] S3 draws the standard curve

[0130] 3) introducing one of the standard solutions of one concentration into the detection cell from the liquid inlet of the detection cell, so that the standard solution fills the detection cell and the standard solution becomes the detection solution; starting the drive motor to make its rotation speed 10000r / min, at this time, the rotation speed of the detection electrode is also 10000r / min; starting the constant potential instrument to make its potential 1.5V vs.SCE, at this time, the detection potential of the detection electrode is 1.5V vs.SCE, after the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time, after the steady-state current measurement is completed, the detection solution in the detection cell is discharged from the liquid outlet;

[0131] 4) According to the method described in step 3), at a driving motor speed of 10000 r / min, the steady-state current of the remaining standard solution when the potential of the constant potential instrument is 1.5 V vs. SCE is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration at a potential of 1.5 V vs. SCE, and the attached Fig.11 It can be seen that the equation of the standard curve at this time is: y = 44.629x-0.3303, R 2 =0.9999;

[0132] S4 detects the test solution

[0133] 5) The solution to be tested is input into the detection cell from the liquid inlet of the detection cell, and the solution to be tested becomes the detection solution. The resistivity meter is started, and the resistivity of the solution to be tested is measured to be R1=3.5Ω / cm. After calculation, the corresponding resistance is 3.5Ω / cm×0.3cm=1.05Ω;

[0134] 6) Start the driving motor and set its speed V1 to 10000 r / min. At this time, the speed of the detection electrode is also 10000 r / min. Start the constant potential instrument and set its potential to 1.5 V vs. SCE. At this time, the detection potential of the detection electrode is 1.5 V vs. SCE. The steady-state current I1 of the test solution is measured to be 150 nA.

[0135] 7) Adjust the potential of the potentiostat to E2 = 1.5 + 150 × 10 -9 ×1.05=1.500V vs.SCE, and the steady-state current I2=151nA of the solution to be tested is measured again. The data storage and processor store the data in the adjacent Fig.11 On the standard curve shown, the hydrogen peroxide concentration of the test solution is 3.391 ng / L, and the hydrogen peroxide concentration of the test solution is displayed by a data display.

[0136] Embodiment 7

[0137] A method for detecting hydrogen peroxide concentration of the present invention is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration of the second embodiment, and the hydrogen peroxide concentration is detected based on the electrochemical oxidation principle, comprising the following steps:

[0138] S1 Preparation

[0139] 1) It is known that the pH value of the solution to be tested is about 1.0, the concentration of hydrogen peroxide is about 5-20 μg / L, a cylindrical boron-doped diamond electrode with a diameter of 4 mm is selected as the detection electrode, the speed V0 of the driving motor is selected to be 1000 r / min, the potential E0 of the potentiostat is selected to be 1.5 V vs. MSE, and a cylindrical boron-doped diamond electrode with a diameter of 4 mm is selected as the counter electrode, and a mercury-mercurous sulfate electrode (MSE) is selected as the reference electrode;

[0140] S2 Preparation of standard solution

[0141] 2) prepare a series of hydrogen peroxide standard solutions with concentrations of 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L, 30 μg / L, 40 μg / L, and 50 μg / L, respectively, and add potassium chloride to dissolve to make the standard solution a saturated solution;

[0142] S3 draws the standard curve

[0143] 3) Inputting one of the standard solutions of one concentration into the detection cell from the liquid inlet of the detection cell, so that the standard solution fills the detection cell and the standard solution becomes the detection solution; starting the drive motor to make its rotation speed 1000r / min, at this time, the rotation speed of the detection electrode is also 1000r / min; starting the constant potential instrument to make its potential 1.5V vs.MSE, at this time, the detection potential of the detection electrode is 1.5V vs.MSE, after the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time, after the steady-state current measurement is completed, the detection solution in the detection cell is discharged from the liquid outlet;

[0144] 4) According to the method described in step 3), at a driving motor speed of 1000 r / min, the steady-state current of the remaining standard solution when the potential of the potentiostat is 1.5 V vs. MSE is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration at a potential of 1.5 V vs. MSE, and the attached Fig.12 It can be seen that the equation of the standard curve at this time is: y = 0.2321x + 0.0106, R 2 =1;

[0145] S4 detects the test solution

[0146] 5) The solution to be tested is introduced into the test cell from the liquid inlet of the test cell. The solution to be tested becomes the test solution. The resistivity meter is started and the resistivity of the solution to be tested is measured to be R1=5×10 5 Ω / cm, after calculation, the corresponding resistance is 5×10 5 Ω / cm×0.3cm=1.5×10 5 Ω;

[0147] 6) Start the driving motor and make its speed V1 1000r / min. At this time, the speed of the detection electrode is also 1000r / min; start the constant potential instrument and make its potential 1.5V vs.MSE. At this time, the detection potential of the detection electrode is 1.5Vvs.MSE, and measure the steady-state current I1 of the solution to be tested = 1.965μA;

[0148] 7) Adjust the potential of the potentiostat to E2 = 1.5 + 1.965 × 10 -6 ×1.5×10 5 Ω=1.795V vs.MSE, and the steady-state current I2=2.102μA of the solution to be tested is measured again. The data storage and processor generate a signal in the vicinity according to the steady-state current 2.102μA at this time. Fig.12 On the standard curve shown, the hydrogen peroxide concentration of the test solution is 9.011 μg / L, and the hydrogen peroxide concentration of the test solution is displayed by a data display.

[0149] Embodiment 8

[0150] A method for detecting hydrogen peroxide concentration of the present invention is a method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration of the second embodiment, and the hydrogen peroxide concentration is detected based on the electrochemical oxidation principle, comprising the following steps:

[0151] S1 Preparation

[0152] 1) According to the pH value of the solution to be tested being 13.0, the solution to be tested is placed in a detection cell, the solution to be tested becomes a detection solution, a cylindrical boron-doped diamond electrode with a diameter of 4 mm is selected as a detection electrode, a driving motor is started to rotate at a speed of 1000 r / min, a constant potential instrument is started to make its potential 0.8 V vs. Hg|HgO, and a steady-state current of the solution to be tested is measured to be 300 μA; a cylindrical boron-doped diamond electrode with a diameter of 4 mm is selected as a counter electrode, and a mercury-mercury oxide electrode is selected as a reference electrode;

[0153] S2 Preparation of standard solution

[0154] 2) prepare a series of hydrogen peroxide standard solutions with concentrations of 1 μg / L, 5 μg / L, 10 μg / L, 20 μg / L, 30 μg / L, 40 μg / L, and 50 μg / L, respectively, and add potassium chloride to dissolve to make the standard solution a saturated solution;

[0155] S3 draws the standard curve

[0156] 3) introducing one of the standard solutions of one concentration into the detection cell from the liquid inlet of the detection cell, so that the standard solution fills the detection cell and the standard solution becomes the detection solution; starting the drive motor to make its rotation speed 1000r / min, at this time, the rotation speed of the detection electrode is also 1000r / min; starting the constant potential instrument to make its potential 0.8V vs.Hg|HgO, at this time, the detection potential of the detection electrode is 0.8V vs.Hg|HgO, after the current response signal is stable, the data storage and processor record the concentration of hydrogen peroxide and its corresponding steady-state current at this time, after the steady-state current measurement is completed, the detection solution in the detection cell is discharged from the liquid outlet;

[0157] 4) According to the method described in step 3), at a driving motor speed of 1000 r / min, the steady-state current of the remaining standard solution when the potential of the constant potential instrument is 0.8V vs.Hg|HgO is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draw a standard curve of current and hydrogen peroxide concentration at a potential of 0.8V vs.Hg|HgO, and the attached Fig.13 It can be seen that the equation of the standard curve at this time is: y = 0.1899x + 0.0124, R 2 =1;

[0158] S4 detects the test solution

[0159] 5) The solution to be tested is introduced into the test cell from the liquid inlet of the test cell. The solution to be tested becomes the test solution. The resistivity meter is started and the resistivity of the solution to be tested is measured to be R1=1.5×10 4 Ω / cm, after calculation, the corresponding resistance is 1.5×10 4 Ω / cm×0.3cm=4.5×10 3 Ω;

[0160] 6) Start the driving motor and make its speed V1 1000r / min. At this time, the speed of the detection electrode is also 1000r / min; start the constant potential instrument and make its potential 0.8V vs.Hg|HgO. At this time, the detection potential of the detection electrode is 0.8Vvs.Hg|HgO, and measure the steady-state current I1 of the solution to be tested = 1.908μA;

[0161] 7) Adjust the potential of the potentiostat to E2 = 0.8 + 1.908 × 10-6 ×4.5×10 3 Ω=0.809V vs.Hg|HgO, and the steady-state current I2=1.936μA of the solution to be tested is measured again. The data storage and processor generate a signal in the vicinity according to the steady-state current 1.936μA at this time. Fig.13 On the standard curve shown, the hydrogen peroxide concentration of the test solution is 10.130 μg / L, and the hydrogen peroxide concentration of the test solution is displayed by a data display.

[0162] Therefore, compared with the prior art, the present invention has the following beneficial effects: the electrochemical electrode for detecting hydrogen peroxide concentration of the present invention is a three-system electrode with a rotating electrode, in which a driving motor drives a rotating body and a detection electrode therein to rotate through a rotating rod; in the electrochemical detection device for detecting hydrogen peroxide concentration obtained therefrom, during the hydrogen peroxide concentration detection process, the hydrogen peroxide concentration on the surface of the detection electrode remains relatively stable and is close to the concentration of the entire hydrogen peroxide solution itself, and under the cooperation of a resistivity tester, the detection error is greatly reduced; moreover, the hydrogen peroxide solution undergoes convection on the surface of the detection electrode, so that the diffusion layer at the interface of the detection electrode / hydrogen peroxide solution becomes thinner, the diffusion rate increases, and the time for the detection current to reach a steady state is shortened, and the time used to reach the steady-state current is usually 5 to 10 seconds, thereby improving the detection efficiency; at the same time, the hydrogen peroxide solution The steady-state current reached by the hydrogen peroxide solution during multiple detections is the same, and the detection results have good reproducibility; in addition, the detection limit of the hydrogen peroxide concentration can be reduced to ng / L or μg / L by increasing the detection potential, rotation speed, effective working area, etc. of the detection electrode; the method for detecting the hydrogen peroxide concentration using the electrochemical detection device for detecting the hydrogen peroxide concentration is easy to operate, has high accuracy, fast detection speed, good repeatability, high sensitivity, low detection limit, and a large detection range, and realizes online rapid detection of the hydrogen peroxide concentration through electrochemical oxidation or reduction method, and can also perform offline rapid detection of the hydrogen peroxide concentration and batch rapid detection, and is widely used in the detection of hydrogen peroxide concentration in different process stages of the anthraquinone method for producing hydrogen peroxide, and can also be used in scenarios where the hydrogen peroxide concentration needs to be monitored in industries such as papermaking, chemical synthesis, and water treatment.

[0163] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electrochemical electrode for detecting hydrogen peroxide concentration, characterized in that: include: A rotating electrode, the rotating electrode comprising a driving motor, a rotating rod and a rotating body, the driving motor is connected to one end of the rotating rod, the other end of the rotating rod is connected to a first current collector, the first current collector is coaxially arranged inside the rotating body, the rotating body is an insulating cylinder, the bottom of the rotating body is inlaid with a detection electrode, the detection electrode is arranged in a cylindrical shape, the top surface of the detection electrode is in contact with the first current collector, the bottom surface of the detection electrode and the bottom surface of the rotating body are on the same horizontal plane and the center of the circle coincides; a stationary electrode, the stationary electrode comprising an insulating shell, a second current collector and a counter electrode, the insulating shell comprising a first shell located at one side of the rotating electrode and a second shell located below the rotating electrode, the second current collector being arranged inside the insulating shell and extending from the first shell to the second shell, one end of the second current collector inside the second shell being connected to the counter electrode, the counter electrode being embedded on the top of the second shell and arranged in parallel directly below the detection electrode, and the top surface of the counter electrode being on the same horizontal plane as the top surface of the second shell; A reference electrode is arranged on a side of the rotating electrode away from the static electrode.

2. The electrochemical electrode for detecting hydrogen peroxide concentration according to claim 1, characterized in that: The rotating rod is provided with an external thread, the first current collector is provided with an internal thread matched with the external thread, and the rotating rod and the first current collector are connected by the external thread and the internal thread; Preferably, the first current collector is arranged in a cylindrical shape, and the cross-sectional area of ​​the first current collector is equal to the cross-sectional area of ​​the detection electrode; Preferably, the diameter of the detection electrode is 0.25-10 mm.

3. The electrochemical electrode for detecting hydrogen peroxide concentration according to claim 1, characterized in that: An insulating sleeve is arranged between the rotating rod and the output shaft of the driving motor, a brush is arranged outside the rotating rod, one end of the brush is connected to the rotating rod, and the other end of the brush is arranged with a first terminal.

4. The electrochemical electrode for detecting hydrogen peroxide concentration according to claim 1, characterized in that: The distance between the bottom surface of the detection electrode and the top surface of the counter electrode is 2-5 mm.

5. The electrochemical electrode for detecting hydrogen peroxide concentration according to any one of claims 1 to 4, characterized in that: The counter electrode is arranged in a cylindrical shape, the cross-sectional area of ​​the counter electrode is not less than the cross-sectional area of ​​the detection electrode, and the center line of the counter electrode and the center line of the detection electrode are on the same vertical line; Preferably, the first shell is vertically arranged on one side of the second shell, the first shell is arranged in a cylindrical shape, the second shell is arranged in a disc shape, and the second current collector is arranged in an L shape.

6. The electrochemical electrode for detecting hydrogen peroxide concentration according to any one of claims 1 to 4, characterized in that: The horizontal distance between the surface of the reference electrode close to the rotating body and the surface of the rotating body close to the reference electrode is 1 to 5 mm.

7. The electrochemical electrode for detecting hydrogen peroxide concentration according to claim 1, characterized in that: The detection electrode is any one of a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode; Preferably, the counter electrode is any one of a lead dioxide electrode, a tin dioxide electrode, and a boron-doped diamond electrode.

8. An electrochemical detection device for detecting hydrogen peroxide concentration, characterized in that: include: A detection cell, wherein a detection solution is provided inside the detection cell, the electrochemical electrode for detecting the concentration of hydrogen peroxide according to any one of claims 1 to 7 is suspended in the detection cell, and the bottoms of the rotating electrode, the static electrode and the reference electrode are all immersed in the detection solution; A constant potential instrument, which is arranged at one side of the detection cell and is respectively connected to the rotating electrode, the static electrode and the reference electrode; A resistivity tester, the resistivity tester is suspended in the detection cell and is used to detect the resistivity of the detection solution in the detection cell; A data storage and processor, the data storage and processor is electrically connected to the potentiostat and is used to store and process data measured by the potentiostat; A data display is connected to the data storage and the processor and is used to display the measured hydrogen peroxide concentration.

9. A method for detecting hydrogen peroxide concentration using the electrochemical detection device for detecting hydrogen peroxide concentration according to claim 8, characterized in that: The following steps are involved: S1 Preparation 1) According to the solution to be tested, determine the detection electrode, the rotation speed V0 of the drive motor and the potential E0 of the constant potential instrument, and determine the counter electrode and the reference electrode; S2 Preparation of standard solution 2) Prepare a series of hydrogen peroxide standard solutions of different concentrations, add potassium chloride, and dissolve to make the standard solutions saturated solutions; S3 draws the standard curve 3) placing a standard solution of one concentration in the detection cell, the standard solution becomes the detection solution, starting the drive motor to make its speed V0, starting the constant potential instrument to make its potential E0, measuring the steady-state current of the standard solution, and the data storage and processor recording the concentration of hydrogen peroxide and its corresponding steady-state current at this time; 4) According to the method described in step 3), when the speed of the driving motor is V0, the steady-state current of the remaining standard solution when the potential of the potentiostat is E0 is measured, and the steady-state current corresponding to each hydrogen peroxide concentration is recorded, and the data storage and processor draws a standard curve of the current and the hydrogen peroxide concentration at the potential E0; S4 detects the test solution 5) The solution to be tested is placed in the detection cell, the solution to be tested becomes the detection solution, the resistivity meter is started, and the resistivity R1 of the solution to be tested is measured; 6) Start the driving motor to make its speed V1, V1 = V0, start the constant potential instrument to make its potential E1, E1 = E0, and measure the steady-state current I1 of the solution to be tested; 7) The potential of the potentiostat is adjusted to E2, E2=E1+I1R1, and the steady-state current I2 of the solution to be tested is measured again. The data storage and processor obtains the hydrogen peroxide concentration of the solution to be tested on the above standard curve according to the steady-state current I2 at this time, and displays the hydrogen peroxide concentration of the solution to be tested on the data display.

10. The method for detecting the concentration of hydrogen peroxide according to claim 9, characterized in that: In the step 1), the method for determining the rotation speed V0 of the detection electrode and the driving motor and the potential E0 of the constant potential instrument is: Place the solution to be tested in the detection cell, the solution to be tested becomes the detection solution, select the detection electrode, start the drive motor, and make its speed V n , start the potentiostat and set its potential to E n , measure the steady-state current I of the solution to be tested n ; If the steady-state current E of the solution to be tested n If the steady-state current E of the solution to be tested is not less than 100 nA, then the detection electrode, the speed of the drive motor and the potential of the constant potential instrument are appropriate. n If the current is very weak, i.e., less than 100 nA, then increase the speed of the drive motor, and / or increase the potential of the potentiostat, and / or replace the detection electrode, and measure the steady-state current of the solution to be tested again until the steady-state current E of the solution to be tested is n Not less than 100nA; if the steady-state current E of the solution to be tested is n If the current is higher than the upper limit of the potentiostat, the speed of the driving motor is reduced, and / or the potential of the potentiostat is reduced, and / or the detection electrode is replaced, and the steady-state current of the solution to be tested is measured again until the steady-state current E of the solution to be tested is n It is smaller than the upper limit of the current of the potentiostat and not less than 100nA, thereby determining the detection electrode, the rotation speed V0 of the drive motor and the potential E0 of the potentiostat.

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