Preparation of chlorine-resistant conductive titanium oxide heterojunction material, and preparation and application of modified screen-printed electrode

Abstract

The invention belongs to the field of environmental monitoring, and provides preparation of an anti-chlorine conductive titanium oxide heterojunction material, and preparation and application of a modified screen-printed electrode. The conductive titanium oxide heterojunction material with chlorine resistance is prepared by regulating and controlling the proportion and the calcination temperature, and the chlorine-resistant conductive titanium oxide modified silk-screen printing electrode is printed by a silk-screen printing technology; the electrode can generate hydroxyl free radicals under proper potential to completely oxidize organic matters in water, has obvious anti-interference capability on chloride ions, can realize accurate detection of chemical oxygen demand in high-chlorine water, has good detection sensitivity, solves the problem that a traditional detection method needs a tedious chloride ion shielding treatment process, and can be applied to detection of chemical oxygen demand in high-chlorine water. The chemical oxygen demand in the high-chlorine water is directly detected, meanwhile, the electrode is small and portable through the screen printing technology, the electrode is coupled with a portable chemical work station, the portability is obviously improved, and the electrode is more suitable for on-site instant application of the high-chlorine water.

Description

Technical Field

[0001] The invention belongs to the field of environmental monitoring, and relates to the preparation of a chlorine-resistant conductive titanium oxide heterojunction material, the preparation of a modified screen-printed electrode, and the electrochemical determination of the chemical oxygen demand concentration in high-chlorine environmental water. Background Art

[0002] Chemical Oxygen Demand (COD) is an important parameter to measure the degree of organic pollution in water bodies. It is defined as the amount of oxygen consumed when reducing substances in water samples react with strong oxidants (such as potassium dichromate) under certain conditions, usually expressed in milligrams of oxygen (mg / L). By measuring COD, we can understand the concentration of reducing substances in the water environment, which plays an important role in monitoring and evaluating the quality of the water ecological environment. Therefore, rapid and real-time detection of chemical oxygen demand has important practical significance for the protection and management of the water environment.

[0003] Potassium dichromate method is a conventional detection method for determining COD, and the result obtained is CODcr. Chloride ions in water bodies have always been the main interfering substances that affect CODcr test results. The methods suitable for CODcr content detection in the prior art mainly include "Dichromate Method for Determination of Chemical Oxygen Demand of Water Quality" (HJ 828-2017) and "Chlorine Correction Method for Determination of Chemical Oxygen Demand of High Chloride Wastewater" (HJ / T 70-2001). The dichromate method shields its interference by adding mercuric sulfate as a masking agent, and the chlorine correction method requires the addition of chlorine to chlorine-free water for measurement and correction. At present, the method of shielding the interference of chloride ions requires a complex processing process with cumbersome steps, and requires the use of highly toxic chemicals. In addition, the waste liquid is difficult to be subsequently treated, which does not conform to the concept of green chemical development and is not environmentally friendly. Therefore, a simple, fast and accurate method for determining chemical oxygen demand that can resist high chlorine interference is urgently needed to be developed.

[0004] The electrochemical method detects the chemical oxygen demand value by generating hydroxyl radicals. It has the characteristics of no need to add chemical reagents, simple operation, short time (<30min), etc., which is a major breakthrough in the determination of chemical oxygen demand. According to Wang Xi et al., in the document entitled Anano-lead dioxide-composite electrochemical sensor for the determination of chemical oxygen demand, the principle of electrochemical detection of chemical oxygen demand is based on the electrochemical signal generated by hydroxyl radicals generated on the surface of the electrode material when oxidizing organic matter in water. This principle is the detection mechanism of most current chemical oxygen demand electrochemical sensors. However, conventional electrode materials cannot shield the interference of chloride ions, resulting in high detection results. Based on the above problems, the present invention designs and prepares a chlorine-resistant conductive titanium oxide heterojunction material that can have a good anti-interference effect on chloride ions. Modifying it on a screen-printed electrode can achieve rapid and accurate determination of chemical oxygen demand in high-chloride water. Summary of the invention

[0005] In order to solve the problem of rapid and accurate detection of chemical oxygen demand in high-chlorine water, the present invention provides a method for preparing a chlorine-resistant titanium oxide heterojunction material. The detection sensitivity of the material to chemical oxygen demand in high-chlorine water is significantly improved. The screen-printed electrode modified with the material relies on screen printing technology to achieve the miniaturization and portability of the electrode, which is more suitable for on-site instant and rapid detection.

[0006] The technical solution of the present invention:

[0007] A method for preparing a chlorine-resistant conductive titanium oxide heterojunction material, comprising the following steps:

[0008] 1) titanium powder and titanium dioxide powder are used as raw materials, weighed and mixed according to a certain proportion, and then ethanol is added and ball-milled for a certain period of time to obtain a precursor 1 after uniform mixing;

[0009] in,

[0010] The titanium dioxide powder is nano-grade anatase titanium dioxide; the molar ratio of titanium powder to titanium dioxide powder is (6-8.5):7; the ball milling speed is 50-300 rpm, and the ball milling time is 10-60 min;

[0011] 2) taking the precursor 1 and evenly spreading it in a corundum boat, pressing it repeatedly to make it uniform, and then calcining it at a high temperature under the protection of an inert gas, so that the precursor 1 is converted into a conductive titanium oxide heterojunction material with chlorine resistance;

[0012] in,

[0013] The temperature of the high-temperature calcination is 800-950° C., the heating rate is 5° C. / min, and the high-temperature calcination insulation time is 1-5 hours.

[0014] A method for preparing a chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode, the steps are as follows:

[0015] 1) Screen printing electrode printing: The screen printing electrode is composed of a conductor layer, a reference electrode layer, a counter electrode layer, a working electrode layer and an insulating layer from bottom to top; a conductor layer is printed on PET using a conductive silver paste, a reference electrode layer is printed on PET using a silver and silver chloride paste, a counter electrode layer is printed on PET using a conductive carbon paste, a working electrode layer is printed on PET using a conductive carbon paste, and an insulating layer is printed on PET using a non-conductive paste. Each layer is printed several times and then placed in an oven to dry at a certain temperature before printing the next layer;

[0016] in,

[0017] The thickness of PET is 0.025-0.25mm, the number of printing times per layer is 3-5 times, the drying temperature of each layer is 60-150℃, and the drying time is 5-40min;

[0018] 2) adding the chlorine-resistant conductive titanium oxide heterojunction material to the aqueous solution containing Nafion117, and ultrasonicating for 1 hour to mix the two, so as to obtain a chlorine-resistant conductive titanium oxide heterojunction material solution;

[0019] in,

[0020] The volume concentration of the aqueous solution containing Nafion117 is 0.5 to 2.5 μL / mL, and the concentration of the chlorine-resistant conductive titanium oxide heterojunction material solution is 0.5 to 2 mg / mL;

[0021] 3) dripping a solution containing a chlorine-resistant conductive titanium oxide heterojunction material onto the working electrode surface of the screen-printed electrode, and drying it naturally to prepare a chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode as an integrated three-electrode detection system;

[0022] in,

[0023] The modification amount of the solution containing the chlorine-resistant conductive titanium oxide heterojunction material is 0.5 to 2.5 μL / mm 2 .

[0024] A method for detecting chemical oxygen demand in high-chlorine water using a screen-printed electrode modified with a chlorine-resistant conductive titanium oxide heterojunction material, the steps are as follows:

[0025] The screen-printed electrode modified with chlorine-resistant conductive titanium oxide heterojunction material integrated in the three-electrode system is connected to the electrochemical workstation through a conversion interface. The high-chloride water sample to be tested is filtered through a membrane and then drop-coated on the surface of the electrode working area. The electrochemical workstation is used for detection to measure the current value. According to the measured current value, a standard curve of concentration and current drawn with glucose as the chemical oxygen demand indicator is used to calculate the concentration of chemical oxygen demand in the sample to be tested.

[0026] in,

[0027] The electrochemical workstation measurement technique is the current-time curve method, the applied potential is +1.0 to +2.2 V, and the measurement time is 10-100 s;

[0028] The standard curve is obtained by: using glucose as a chemical oxygen demand indicator, using an electrochemical workstation to record the electrochemical response signals of the working electrode to different concentrations of glucose in a sodium chloride solution at a fixed potential, and according to the change of the response signal, taking the logarithm of the concentration value of glucose converted into chemical oxygen demand equivalent as the abscissa and taking the current value as the ordinate to obtain the standard curve and the linear equation;

[0029] in,

[0030] The concentration of the sodium chloride solution is 0.1-1.0 mol / L; the concentration of glucose is 0.0-500.0 mg / L.

[0031] Beneficial effects of the present invention: The chlorine-resistant conductive titanium oxide heterojunction material of the present invention modifies the screen-printed electrode. By adjusting the ratio of titanium powder to titanium dioxide and the calcination temperature, a conductive titanium oxide heterojunction material with chlorine-resistant properties is synthesized, and it is modified on the screen-printed electrode, which can effectively resist the interference of chloride ions and highly sensitively detect the chemical oxygen demand in high-chlorine water. The established high-chlorine water chemical oxygen demand detection method has a detection range of 0.0 to 500.0 mg / L for chemical oxygen demand, a detection limit of 0.07 mg / L, and a measurement time as short as about 30 seconds, which is much shorter than the existing conventional chemical oxygen demand detector. This chlorine resistance comes from the titanium monoxide part in the heterojunction structure. The titanium monoxide part has abundant oxygen vacancies and low-valent titanium species with weak adsorption force on chloride ions, can effectively resist the interference of chloride ions, and can generate sufficient hydroxyl radicals at an appropriate potential without being affected by chloride ions. The present invention has the advantages of low cost, easy operation, low detection limit, good stability, selectivity, anti-interference and portability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Diagram of the structure of screen-printed electrodes modified with chlorine-resistant conductive titanium oxide heterojunction materials.

[0033] Figure 2Actual photo of screen-printed electrodes modified with chlorine-resistant conductive titanium oxide heterojunction materials.

[0034] Figure 3 Scanning electron microscope image of the synthesized chlorine-resistant conductive titanium oxide heterojunction material.

[0035] Figure 4 This is a scanning electron microscope image of the synthesized titanium dioxide material without chlorine resistance.

[0036] Figure 5 Standard curve for detecting chemical oxygen demand in high-chloride water based on a screen-printed electrode modified with chlorine-resistant conductive titanium oxide heterojunction material coupled to a portable electrochemical workstation.

[0037] Figure 6 The current-time curve of the screen-printed electrode modified with chlorine-resistant conductive titanium oxide junction material and the screen-printed electrode without chlorine resistance coupled with a portable electrochemical workstation to detect chemical oxygen demand in high-chlorine water.

[0038] Figure 7 The current-time curve of the screen-printed electrode modified with chlorine-resistant conductive titanium oxide junction material and the screen-printed electrode without chlorine resistance coupled with a portable electrochemical workstation to detect chemical oxygen demand in high-chlorine water.

[0039] Figure 8 The current-time curve of the screen-printed electrode modified with chlorine-resistant conductive titanium oxide junction material and the screen-printed electrode without chlorine resistance coupled with a portable electrochemical workstation to detect chemical oxygen demand in high-chlorine water.

[0040] Fig. 9 Current-time curve of the screen-printed electrode modified with chlorine-resistant conductive titanium oxide junction material coupled with a portable electrochemical workstation for detecting chemical oxygen demand in high-chloride water.

[0041] Fig.10 Test diagram of the anti-interference ability of detecting chemical oxygen demand in high-chlorine water based on the chlorine-resistant conductive titanium oxide junction material modified screen-printed electrode coupled with a portable electrochemical workstation.

[0042] In the figure: 1 the conductor layer is prepared by printing conductive silver paste; 2 the working electrode layer is prepared by printing conductive carbon paste; 3 the counter electrode layer is prepared by printing conductive carbon paste; 4 the reference electrode layer is prepared by printing silver / silver chloride paste; 5 the insulating layer is prepared by printing non-conductive paste; 6 the chlorine-resistant conductive titanium oxide screen-printed electrode is obtained after modifying the chlorine-resistant conductive titanium oxide material solution. DETAILED DESCRIPTION

[0043] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0044] Example 1: Preparation of chlorine-resistant conductive titanium oxide heterojunction material

[0045] 1) 0.5 g titanium powder and 1.5 g nano-grade anatase titanium dioxide powder were mixed and placed in a planetary ball mill, and ethanol solvent was added and ball milled at 200 rpm for 30 min to obtain a precursor 1;

[0046] 2) Weigh 1.0 g of the precursor 1 and spread it evenly in a corundum boat, press it repeatedly to make it uniform, and then calcine it at 800° C. under argon gas protection, with a heating rate of 5° C. / min and a high-temperature calcination time of 3 h; so that the precursor 1 is converted into a conductive titanium oxide heterojunction material with chlorine resistance;

[0047] The present invention uses titanium powder and titanium dioxide as raw materials, and synthesizes a conductive titanium oxide heterojunction material with chlorine resistance by calcining at a specific temperature under a specific ratio. The scanning electron microscope image of the conductive titanium oxide heterojunction material with chlorine resistance prepared by the method of the present invention is shown in FIG. Figure 3 .

[0048] The synthesis conditions of chlorine-resistant conductive titanium oxide heterojunction materials are shown in Table 1:

[0049] Table 1

[0050]

[0051]

[0052] Example 2: Preparation of chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrodes

[0053] 1) Printing of screen-printed electrodes: The screen-printed electrodes are, from bottom to top, a PET substrate, a wire layer, a reference electrode layer, a counter electrode layer, a working electrode layer and an insulating layer; the wire layer is printed on PET by a screen printer using a conductive silver paste, and the wire layer is printed three times and then placed in an oven at 135°C for heating for 30 min; the reference electrode layer is printed on PET by a screen printer using silver and silver chloride paste, and the reference electrode layer is printed three times and then placed in an oven at 135°C for heating for 30 min; the counter electrode layer is printed on PET by a screen printer using a conductive carbon paste, and the counter electrode layer is printed three times and then placed in an oven at 135°C for heating for 30 min; the working electrode layer is printed on PET by a screen printer using a conductive carbon paste, and the working electrode layer is printed three times and then placed in an oven at 135°C for heating for 30 min; the insulating layer is printed on PET by a screen printer using a non-conductive paste, and the insulating layer is printed three times and then placed in an oven at 135°C for heating for 30 min;

[0054] 2) Weigh the synthesized chlorine-resistant conductive titanium oxide heterojunction material and add it to 1 mL of an aqueous solution containing 2.5 μL of Nafion 117, and mix the two by ultrasonication for 1 h to obtain a chlorine-resistant conductive titanium oxide heterojunction material solution with a concentration of 1.0 mg / mL;

[0055] 3) 20 μL of the chlorine-resistant conductive titanium oxide heterojunction material solution was drop-coated on the working electrode surface of the screen-printed electrode and dried naturally to prepare a chlorine-resistant conductive titanium oxide screen-printed electrode as an integrated three-electrode detection system;

[0056] The present invention uses conductive silver paste, silver / silver chloride paste, conductive carbon paste and non-conductive white paste to print screen-printed electrodes through a screen printer, and prepares chlorine-resistant conductive titanium oxide screen-printed electrodes by modifying chlorine-resistant conductive titanium oxide heterojunction materials. The structural diagram and physical diagram of the screen-printed electrodes modified with chlorine-resistant conductive titanium oxide heterojunction materials prepared by the method of the present invention are shown in Figure 1 and Figure 2 .

[0057] Example 3: Standard curve

[0058] The method for drawing a standard curve for detecting the chemical oxygen demand of high-chlorine water by the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode of the present invention is as follows: glucose is used as the chemical oxygen demand indicator, and glucose of different known concentrations (concentration range: 0.0-500.0 mg / L) is prepared in a 0.1 mol / L sodium chloride solution, 1 mL of glucose solution of each concentration is dripped into the working electrode area of ​​the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode to cover the entire three-electrode area, and the time-current curve is tested at a constant voltage of +2.0 V by an external portable electrochemical workstation, and the current-time curve of 30 seconds is recorded, and the standard curve is drawn with the chemical oxygen demand concentration as the Log value as the horizontal coordinate and the current value at the 30th second as the vertical coordinate. Figure 5 As shown, the linear equation is I / μA = 8.88 × Log [c / mg / L] + 76.3 9 (R 2 =0.9894), the detection limit is 0.07 mg / L;

[0059] Comparative Example 1: Preparation of screen-printed electrodes without chlorine resistance

[0060] Referring to Example 1, titanium powder was not added, and other conditions remained unchanged to obtain a titanium dioxide material without chlorine resistance. The scanning electron microscope image of the synthesized titanium dioxide material without chlorine resistance is as follows: Figure 4 As shown; referring to Example 2, the chlorine-resistant conductive titanium oxide heterojunction material is replaced with a titanium dioxide material without chlorine resistance, and other conditions remain unchanged to obtain a screen-printed electrode without chlorine resistance;

[0061] The chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode of Example 3 was replaced with a screen-printed electrode without chlorine resistance, and the sample test was carried out according to Example 3. The time-current curve was tested at a constant voltage of +2.0V by an external portable electrochemical workstation, and the current value of 15.0mg / L glucose at the 30th second was recorded and compared with the test results of the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode. Figure 6 As shown, it can be seen that the response current value of the screen-printed electrode without chlorine resistance used for comparison is high, but the response current value of the screen-printed electrode modified with conductive titanium oxide heterojunction material with chlorine resistance synthesized in Example 1 to the chemical oxygen demand in high-chlorine water is normal. This is because the presence of chloride ions will interfere with the electrical signals generated by the electrode material in the oxidation process of organic matter, and the screen-printed electrode modified with conductive titanium oxide heterojunction material can well shield the electrochemical signal interference caused by such chloride ions. This performance improvement is attributed to the introduction of a titanium oxide structure containing rich oxygen vacancy defects, which can reduce the adsorption force of chloride ions and accelerate electron transfer as a reaction active site, thereby effectively increasing the hydroxyl radical yield of the electrode, thereby improving the accuracy of the detection signal of chemical oxygen demand under high chlorine conditions.

[0062] Comparative Example 2: Preparation of screen-printed electrodes without chlorine resistance

[0063] Referring to Example 1, the titanium dioxide material without chlorine resistance is obtained by calcining at a high temperature of 600 degrees, while other conditions remain unchanged; referring to Example 2, the chlorine-resistant conductive titanium oxide heterojunction material is replaced with a titanium dioxide material without chlorine resistance, while other conditions remain unchanged, to obtain a screen-printed electrode without chlorine resistance;

[0064] The chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode of Example 3 was replaced with a screen-printed electrode without chlorine resistance, and the sample test was carried out according to Example 3. The time-current curve was tested at a constant voltage of +2.0V by an external portable electrochemical workstation, and the current value of 15.0mg / L glucose at the 30th second was recorded and compared with the test results of the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode. Figure 7 shown.

[0065] Comparative Example 3: Preparation of screen-printed electrodes without chlorine resistance

[0066] Referring to Example 1, calcining at a high temperature of 1000 degrees, while other conditions remain unchanged, obtains a titanium oxide material without chlorine resistance; referring to Example 2, replacing the chlorine-resistant conductive titanium oxide heterojunction material with a titanium oxide material without chlorine resistance, while other conditions remain unchanged, obtains a screen-printed electrode without chlorine resistance;

[0067] The chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode of Example 3 was replaced with a screen-printed electrode without chlorine resistance, and the sample test was carried out according to Example 3. The time-current curve was tested at a constant voltage of +2.0V by an external portable electrochemical workstation, and the current value of 15.0mg / L glucose at the 30th second was recorded and compared with the test results of the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode. Figure 8 shown.

[0068] Experimental Example 1: Comparison of the anti-interference ability of the screen-printed electrode modified with the chlorine-resistant conductive titanium oxide heterojunction material in detecting chemical oxygen demand in high-chlorine water

[0069] Taking glucose as the indicator of chemical oxygen demand, 15.0 mg / L glucose was prepared in 0.1 mol / L sodium chloride solution and 0.1 mol / L sodium sulfate solution, respectively. 1 mL of the glucose solution in sodium sulfate solution was dripped into the working electrode area of ​​the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode to cover the entire three-electrode area. The time-current curve was tested at a constant voltage of +2.0 V by an external portable electrochemical workstation, and the current value of 15.0 mg / L glucose at the 30th second was recorded and compared with the test result of the glucose solution dripped with 1 mL of sodium chloride solution. Fig. 9 As shown, the electrochemical response of the screen-printed electrode modified with the chlorine-resistant conductive titanium oxide heterojunction material to chemical oxygen demand has basically not changed, indicating that it has a strong ability to resist chloride ion interference and can achieve accurate detection of chemical oxygen demand in high-chloride water.

[0070] Experimental Example 2: Anti-interference test of the detection of chemical oxygen demand in high-chlorine water based on the screen-printed electrode modified with the conductive titanium oxide heterojunction material with chlorine resistance

[0071] Taking glucose as the indicator of chemical oxygen demand, 15.0 mg / L glucose was prepared in 0.1 mol / L sodium sulfate, potassium chloride, calcium chloride, magnesium chloride, copper chloride, sodium nitrate and sodium chloride solutions respectively. 1 mL of glucose solution under each solution was dripped into the working electrode area of ​​the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode to cover the entire three-electrode area. The time-current curve was tested at a constant voltage of +2.0 V by an external portable electrochemical workstation, and the current value of 15.0 mg / L glucose at the 30th second was recorded. The results are as follows: Fig.10 As shown, the electrochemical response of the chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode to chemical oxygen demand has basically not changed, indicating that it has strong anti-interference ability.

[0072] Experimental Example 3: Application of the screen-printed electrode modified by the conductive titanium oxide heterojunction material with chlorine resistance, i.e., detection of chemical oxygen demand content in high-chlorine environmental water

[0073] 1) Take a seawater sample containing high chloride concentration and simply filter it through a 0.22μm filter membrane;

[0074] 2) Take 1 mL and drop it on the working electrode area of ​​the screen-printed electrode modified with the chlorine-resistant conductive titanium oxide heterojunction material, completely covering the three-electrode area. The time-current curve is tested at a constant voltage of +2.0V by an external portable electrochemical workstation, and the current value at the 30th second is recorded. Each water sample is tested three times independently and compared with the results of the potassium permanganate standard method. The actual water sample experimental results are shown in Table 2.

[0075] Table 2

[0076]

[0077] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Other changes or modifications can be made within the knowledge of ordinary technicians in this field. It is not necessary and impossible to list all the embodiments here. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a chlorine-resistant conductive titanium oxide heterojunction material, characterized in that: Here are the steps: 1) titanium powder and titanium dioxide powder are used as raw materials, weighed and mixed according to a certain proportion, and then ethanol is added and ball-milled for a certain period of time to obtain a precursor 1 after uniform mixing; 2) Precursor 1 is evenly spread in a corundum boat, and after repeated pressing, it is evenly spread and then calcined at high temperature under the protection of an inert gas, so that precursor 1 is converted into a conductive titanium oxide heterojunction material with chlorine resistance.

2. The preparation method according to claim 1, characterized in that: The titanium dioxide powder is nano-grade anatase titanium dioxide; the molar ratio of titanium powder to titanium dioxide powder is (6-8.5):7; the ball milling speed is 50-300 rpm, and the ball milling time is 10-60 min.

3. The preparation method according to claim 1, characterized in that: The temperature of the high-temperature calcination is 800-950° C., the heating rate is 5° C. / min, and the high-temperature calcination insulation time is 1-5 hours.

4. A method for preparing a chlorine-resistant conductive titanium oxide heterojunction material modified screen-printed electrode, characterized in that: Here are the steps: 1) Screen printing electrode printing: The screen printing electrode is composed of a conductor layer, a reference electrode layer, a counter electrode layer, a working electrode layer and an insulating layer from bottom to top; a conductor layer is printed on PET using a conductive silver paste, a reference electrode layer is printed on PET using a silver and silver chloride paste, a counter electrode layer is printed on PET using a conductive carbon paste, a working electrode layer is printed on PET using a conductive carbon paste, and an insulating layer is printed on PET using a non-conductive paste. Each layer is printed several times and then placed in an oven to dry at a certain temperature before printing the next layer; 2) adding the chlorine-resistant conductive titanium oxide heterojunction material to the aqueous solution containing Nafion117, and ultrasonicating for 1 hour to mix the two, so as to obtain a chlorine-resistant conductive titanium oxide heterojunction material solution; 3) A solution containing a chlorine-resistant conductive titanium oxide heterojunction material is drop-coated on the working electrode surface of the screen-printed electrode and dried naturally to prepare a chlorine-resistant conductive titanium oxide heterojunction material-modified screen-printed electrode as an integrated three-electrode detection system.

5. The preparation method according to claim 4, characterized in that: The thickness of the PET is 0.025-0.25 mm, the number of printing times for each layer is 3-5 times, the drying temperature for each layer is 60-150° C., and the drying time is 5-40 minutes.

6. The preparation method according to claim 4, characterized in that: The volume concentration of the aqueous solution containing Nafion117 is 0.5-2.5 μL / mL, the concentration of the chlorine-resistant conductive titanium oxide heterojunction material solution is 0.5-2 mg / mL; the modification amount of the chlorine-resistant conductive titanium oxide heterojunction material solution is 0.5-2.5 μL / mm 2 .

7. A method for detecting chemical oxygen demand in high-chlorine water using a screen-printed electrode modified with a chlorine-resistant conductive titanium oxide heterojunction material, characterized in that: Here are the steps: The screen-printed electrode modified with chlorine-resistant conductive titanium oxide heterojunction material integrated in the three-electrode system is connected to the electrochemical workstation through a conversion interface. The high-chloride water sample to be tested is filtered through a membrane and then drop-coated on the surface of the electrode working area. The electrochemical workstation is used for detection to measure the current value. According to the measured current value, a standard curve of concentration and current drawn with glucose as the chemical oxygen demand indicator is used to calculate the concentration of chemical oxygen demand in the sample to be tested.

8. The method for detecting chemical oxygen demand in high-chlorine water according to claim 7, characterized in that: The measurement technique of the electrochemical workstation is the current-time curve method, the applied potential is +1.0~+2.2V, and the measurement time is 10-100s.

9. The method for detecting chemical oxygen demand in high-chlorine water according to claim 8, characterized in that: The standard curve is obtained by taking glucose as a chemical oxygen demand indicator, using an electrochemical workstation to record the electrochemical response signals of the working electrode to different concentrations of glucose in a sodium chloride solution at a fixed potential, and according to the change of the response signal, taking the logarithm of the concentration value of glucose converted into chemical oxygen demand equivalent as the horizontal coordinate and taking the current value as the vertical coordinate to obtain the standard curve and the linear equation.

10. The method for detecting chemical oxygen demand in high-chlorine water according to claim 9, characterized in that: The concentration of the sodium chloride solution is 0.1-1.0 mol / L; the concentration of glucose is 0.0-500.0 mg / L.

Images