An electrochemical array electrode for integrated water quality online monitoring

Abstract

The application relates to the technical field of water quality monitoring, in particular to an electrochemical array electrode for comprehensive water quality online monitoring; the electrochemical array electrode comprises a substrate layer, a conductive wiring layer and an insulating shielding layer, and is provided with electrodes on the substrate layer; the electrodes comprise multiple working electrodes, a counter electrode and a reference electrode; the conductive wiring layer is provided with pins; the pins are electrically connected with the corresponding electrodes through wires. The multiple working electrodes are integrated on the same small substrate, high-throughput, multi-parameter synchronous real-time detection is realized, the volume of the sensor is greatly reduced, the sensor is suitable for online, trace and portable water quality monitoring scenes, the L-shaped reference electrode ensures that the physical distance and solution resistance from any working electrode to the reference electrode are basically consistent, the uniformity of the electrochemical potential distribution of each channel in the working electrode is ensured, and the signal error between the channels is reduced.

Description

Technical Field

[0001] This invention relates to the field of water quality monitoring technology, specifically to an electrochemical array electrode for comprehensive online water quality monitoring. Background Technology

[0002] With the acceleration of industrialization and the increasing demands of environmental regulations, real-time water quality monitoring has become a core component in environmental protection, drinking water safety, and industrial wastewater treatment. Electrochemical analysis, due to its advantages such as small equipment size, fast response speed, low cost, and ease of integration, has become one of the mainstream technologies for online water quality monitoring. However, in practical applications, the aquatic environment is often extremely complex. It not only contains multiple target ions but also a large amount of organic interference, suspended particles, and fluctuating pH levels. This places extremely high demands on the sensor's detection throughput, anti-interference ability, and long-term operational stability.

[0003] Existing multi-parameter water quality monitoring methods employ multiple individual probes pieced together or integrated within large flow-through tanks. This approach results in bulky and power-consuming equipment, making it difficult to deploy in confined spaces. Furthermore, traditional single-channel electrodes, when dealing with complex water qualities, can only detect different indicators sequentially in batches or at different times, which is time-consuming and cannot capture the changing trends of multiple components in the water sample at the same time point or within the same small space, resulting in poor timeliness. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides an electrochemical array electrode for comprehensive online water quality monitoring.

[0005] The technical solution of the present invention is: an electrochemical array electrode for comprehensive online water quality monitoring, comprising a substrate layer, and a conductive wiring layer and an insulating shielding layer arranged sequentially from top to bottom on the substrate layer, an electrode being provided on the substrate layer below the insulating shielding layer, the electrode comprising a plurality of horizontally arranged and equally spaced working electrodes, and an L-shaped counter electrode and a reference electrode arranged sequentially from top to bottom below the working electrodes, the conductive wiring layer having pins corresponding to each electrode, the pins being electrically connected to the corresponding electrode through wires provided in the insulating shielding layer.

[0006] Note: The array electrode described above integrates multiple working electrodes on the same micro substrate, enabling high-throughput, multi-parameter synchronous real-time detection, and significantly reducing the sensor size, making it suitable for online, micro-volume, and portable water quality monitoring scenarios. The L-shaped reference electrode ensures that the physical distance and solution resistance between any working electrode and the reference electrode are basically consistent, guaranteeing the uniformity of the electrochemical potential distribution in each channel of the working electrode and reducing signal errors between channels.

[0007] Furthermore, the substrate layer is provided with a serpentine temperature sensor for temperature compensation of the working electrode, and the conductive wiring layer is provided with pins corresponding to the serpentine temperature sensor. The pins are electrically connected to the serpentine temperature sensor through wires provided in the insulating shielding layer.

[0008] Note: The serpentine temperature sensor can increase the effective resistance length to respond to local temperature changes in water samples in milliseconds, providing accurate real-time temperature compensation for potentiometric measurements and significantly improving the measurement accuracy of the electrode under ambient temperature fluctuations.

[0009] Furthermore, the conductive wiring layer is made by screen printing conductive silver paste or carbon paste onto the substrate layer, and the thickness of the conductive wiring layer is 8~12µm.

[0010] Note: The above-mentioned conductive wiring layer has stable chemical properties and can remain inert within the working potential window to effectively transmit electrical signals and ensure the authenticity of the electrical signals.

[0011] Furthermore, the insulating shielding layer is made by brushing insulating oil onto the base layer and then curing it, and the thickness of the insulating shielding layer is 30~40µm.

[0012] Note: The above-mentioned insulating shielding layer can effectively protect the conductor, significantly reduce the background current, greatly improve the signal-to-noise ratio, and ensure the detection sensitivity of the array electrode.

[0013] Furthermore, the working electrode is composed of a conductive layer, a solid contact layer disposed on the conductive layer, and an ion-selective film disposed on the solid contact layer; wherein the thickness of the conductive layer is 5~10µm, the thickness of the solid contact layer is 2~6µm, and the thickness of the ion-selective film is 5~10µm.

[0014] Note: The working electrode with the above structure eliminates the water layer effect that is prone to occur in traditional wire-coated electrodes, greatly improving the potential stability and anti-drift capability of the electrode in long-term online monitoring.

[0015] Furthermore, the ion-selective membrane is any one of an ammonium ion-selective membrane, a nitrate ion-selective membrane, a chloride ion-selective membrane, or a hydrogen ion-selective membrane.

[0016] Note: By using different ion-selective membranes, the working electrode can achieve highly specific identification and parallel capture of multiple components in complex water bodies, ensuring the detection accuracy of the array electrode.

[0017] Furthermore, the method for preparing the ion-selective membrane is as follows: dissolve 0.95~1.05mg of the substrate component in 5ul tetrahydrofuran to prepare a substrate solution, and then drop the substrate solution onto the surface of the solid contact layer. The substrate components of the ammonium ion selective membrane, by weight percentage, include: 6.7~7.1% non-viable bacteria, 92.2~92.6% nitrophenyl octyl ether, 0.5~0.9% potassium tetra(4-chlorophenyl)borate, and the balance being polyvinyl chloride; The substrate composition of the nitrate ion-selective membrane, by weight percentage, includes: 5.0~5.4% nitrate ion carrier VI, 46.9~47.3% dibutyl phthalate, 0.4~0.8% tetraoctyl ammonium chloride, and the balance being polyvinyl chloride; The substrate composition of the chloride ion selective membrane, by weight percentage, includes: 0.8~1.2% chloride ion carrier IV, 65.2~65.6% nitrophenyl octyl ether, 0.4~0.8% tetraoctyl ammonium chloride, and the balance being polyvinyl chloride; The substrate composition of the hydrogen ion selective membrane, by weight percentage, includes: 0.8~1.2% hydrogen ion carrier I, 0.3~0.7% potassium tetra(4-chlorophenyl)borate, 65.3~65.7% dioctyl sebacate, and the balance being polyvinyl chloride.

[0018] Note: The ion-selective membrane with the above-mentioned components can accurately respond to the target ion, avoid cross-interference of the target ion by other ions, and ensure the detection accuracy of the working electrode.

[0019] Furthermore, the solid contact layer is prepared by: drop-coating a PEDOT:PSS aqueous dispersion onto a conductive layer and drying it to obtain a solid contact layer.

[0020] Note: The above-mentioned solid contact layer film has good hydrophobicity, which can effectively block water molecules from penetrating, prevent the formation of a harmful water layer between the ion-selective membrane and the substrate that causes potential drift, and improve the potential stability of the working electrode.

[0021] Furthermore, the method for preparing the solid contact layer includes the following steps: S1. Add sodium nitrate and silver nitrate to deionized water and stir for 5-10 minutes to obtain the electrolyte; wherein the mass ratio of sodium nitrate, silver nitrate and deionized water is 1:1-1.5:10-15. S2. Add pyrrole to the electrolyte at room temperature, then apply an electric field to the electrolyte while heating. The heating rate is 2-4℃ / min, the initial voltage of the electric field is 0.6-0.8V, and the voltage of the electric field is gradually increased at a rate of 0.1-0.2V / min until the electrolyte temperature reaches 35-40℃. After that, the voltage of the electric field becomes constant. Add sodium polystyrene sulfonate to the electrolyte, then place the electrolyte in an ice bath at 0-5℃ and apply ultrasound to the electrolyte. The power of the ultrasound is 80-120W, the frequency is 20-25kHz, and the ultrasonic treatment is carried out for 20-30 minutes to obtain a suspension. The amount of pyrrole added accounts for 10-15% of the total mass of the electrolyte, and the amount of sodium polystyrene sulfonate added accounts for 6-12% of the total mass of the electrolyte. S3. Filter and dry the suspension to obtain solid particles; S4. Add solid particles and ethylene glycol to deionized water, stir for 10-15 minutes to obtain a mixture, drop the mixture onto the conductive layer, and dry to obtain a solid contact layer; wherein, the mass ratio of solid particles, ethylene glycol and deionized water is 1:0.1-0.2:8-10.

[0022] Explanation: The above solid contact layer undergoes a polymerization reaction of pyrrole under the action of an electric field. During the polymerization process, silver ions are coordinated to improve the conductivity of the solid contact layer. Furthermore, sodium polystyrene sulfonate can enter the polypyrrole chain as a dopant anion to provide more ion exchange sites. This results in a solid contact layer with high capacitance and the formation of a stable ion-electron conduction channel, thereby improving the potential stability of the working electrode.

[0023] The beneficial effects of this invention are: The array electrode of this invention integrates multiple working electrodes on the same micro substrate, enabling high-throughput, multi-parameter synchronous real-time detection, and significantly reducing the sensor size, making it suitable for online, micro-scale, and portable water quality monitoring scenarios. The L-shaped reference electrode ensures that the physical distance and solution resistance between any working electrode and the reference electrode are basically consistent, guaranteeing the uniformity of the electrochemical potential distribution of each channel in the working electrode and reducing signal errors between channels. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the array electrode of the present invention; Among them, 1-conductive wiring layer, 11-pin, 2-insulating shielding layer, 21-wire, 3-base layer, 31-reference electrode, 32-counter electrode, 33-working electrode, and 34-serpentine temperature sensor. Detailed Implementation

[0025] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0026] Example 1: An electrochemical array electrode for comprehensive online water quality monitoring includes a substrate layer 3, and a conductive wiring layer 1 and an insulating shielding layer 2 arranged sequentially from top to bottom on the substrate layer 3. Electrodes are arranged on the substrate layer 3 below the insulating shielding layer 2. The electrodes include four horizontally and equally spaced working electrodes 33, and L-shaped counter electrodes 32 and reference electrodes 31 arranged sequentially from top to bottom below the working electrodes 33. The conductive wiring layer 1 has pins 11 corresponding to each electrode. The pins 11 are electrically connected to the corresponding electrodes through wires 21 provided in the insulating shielding layer 2. The substrate layer 3 is made of PET material, with a size of 2.8cm × 4.2cm and a thickness of 200µm. The counter electrode 32 is made by inkjet printing carbon paste on the substrate layer 3 with a printing thickness of 6µm. The reference electrode 31 is made by inkjet printing Ag / AgCl paste on the substrate layer 3 with a printing thickness of 6µm. The wires 21 are made by inkjet printing conductive silver paste on the substrate layer 3. The substrate layer contains a serpentine temperature sensor 34 for temperature compensation of the working electrode 33. The conductive wiring layer 1 contains pins 11 corresponding to the serpentine temperature sensor 34. The pins 11 are electrically connected to the serpentine temperature sensor 34 through wires 21 provided in the insulating shielding layer 2. The serpentine temperature sensor 34 is made by inkjet printing carbon paste on the substrate layer 3. The conductive wiring layer 1 is made by screen printing carbon paste onto the substrate layer 3, and the thickness of the conductive wiring layer 1 is 10µm; the insulating shielding layer 2 is made by brushing insulating oil onto the substrate layer 3 and then curing it, and the thickness of the insulating shielding layer 2 is 35µm; the insulating oil is a commercially available product. The working electrode 33 consists of a conductive layer, a solid contact layer disposed on the conductive layer, and an ion-selective film disposed on the solid contact layer. The conductive layer is made by inkjet printing carbon paste on the substrate layer 3 with a printing thickness of 6µm. The solid contact layer has a thickness of 4µm, and the ion-selective film has a thickness of 6µm. The four working electrodes 33 are ammonium ion-selective electrodes, nitrate ion-selective electrodes, chloride ion-selective electrodes, or hydrogen ion-selective electrodes, respectively. The method for preparing the ion-selective membrane is as follows: 1 mg of the substrate component is dissolved in 5 μL of tetrahydrofuran to prepare a substrate solution, and the substrate solution is drop-coated onto a solid contact layer. The ion-selective membrane substrate on the ammonium ion-selective electrode comprises, by weight percentage: 6.9% viable bacteriocin, 92.4% nitrophenyl octyl ether, 0.7% potassium tetrakis(4-chlorophenyl)borate, and the balance being polyvinyl chloride; The ion-selective membrane substrate composition on the nitrate ion-selective electrode, by weight percentage, includes: 5.2% nitrate ion carrier VI, 47.1% dibutyl phthalate, 0.6% tetraoctyl ammonium chloride, and the balance being polyvinyl chloride; The ion-selective membrane substrate composition on the chloride ion selective electrode includes, by weight percentage: 1% chloride ion carrier IV, 65.4% nitrophenyl octyl ether, 0.6% tetraoctyl ammonium chloride, and the balance being polyvinyl chloride; The ion-selective membrane substrate composition on the hydrogen ion selective electrode includes, by weight percentage: 1% hydrogen ion carrier I, 0.5% potassium tetra(4-chlorophenyl)borate, 65.5% dioctyl sebacate, and the balance being polyvinyl chloride; The solid contact layer was prepared by drop-coating a PEDOT:PSS aqueous dispersion onto a conductive layer at a volume of 5 μL. After drying, a solid contact layer was obtained. The PEDOT:PSS aqueous dispersion was a commercially available product, wherein the mass ratio of PEDOT to PSS was 1:6, and the mass percentage of water was 98.5%. The carbon paste used in this embodiment is a commercially available conductive carbon paste, and the Ag / AgCl paste is a commercially available Ag / AgCl conductive silver paste. The temperature compensation method for the four ion-selective membranes is as follows: electrode titration experiments were performed on the four working electrodes 33 at 5, 15, 25, 35, and 45 degrees Celsius. The ammonium ion-selective electrode was used for ammonia nitrogen concentrations of 1–64 mg / L, the nitrate ion-selective electrode for nitrate nitrogen concentrations of 1–64 mg / L, the chloride ion-selective electrode for potassium chloride concentrations of 1–1250 mg / L, and the hydrogen ion-selective electrode for pH values ​​from 5 to 9. The titration data were then fitted to obtain the values ​​for each working electrode. slope Function; Ammonium ion selective electrode slope =0.1457x + 48.3376, nitrate ion-selective electrode slope = -0.1203x-46.66, Chloride ion selective electrode slope = -0.1633x-48.4421, Hydrogen ion selective electrode slope =0.1533x + 44.6379; Then slope Substitute the function into the following equation: in, E This is the compensated potential. E 0The onset potentials are: -98.7271 mV for the ammonium ion selective electrode, 193.5 mV for the nitrate ion selective electrode, 262.25 mV for the chloride ion selective electrode, and -134.51 mV for the hydrogen ion selective electrode. ai This represents ion activity.

[0027] Example 2: This example is basically the same as Example 1, except that the substrate composition of the ammonium ion selective membrane, by weight percentage, includes: 6.7% non-viable bacteria, 92.2% nitrophenyl octyl ether, 0.5% potassium tetra(4-chlorophenyl)borate, and the remainder is polyvinyl chloride.

[0028] Example 3: This example is basically the same as Example 1, except that the substrate composition of the ammonium ion selective membrane, by weight percentage, includes: 7.1% non-viable bacteria, 92.6% nitrophenyl octyl ether, 0.9% potassium tetrakis(4-chlorophenyl)borate, and the remainder is polyvinyl chloride.

[0029] Example 4: This example is basically the same as Example 1, except that the substrate composition of the nitrate ion-selective membrane, by weight percentage, includes: 5.0% nitrate ion carrier VI, 46.9% dibutyl phthalate, 0.4% tetraoctyl ammonium chloride, and the remainder is polyvinyl chloride.

[0030] Example 5: This example is basically the same as Example 1, except that the substrate composition of the nitrate ion-selective membrane, by weight percentage, includes: 5.4% nitrate ion carrier VI, 47.3% dibutyl phthalate, 0.8% tetraoctyl ammonium chloride, and the remainder is polyvinyl chloride.

[0031] Example 6: This example is basically the same as Example 1, except that the substrate composition of the chloride ion selective membrane, by weight percentage, includes: 0.8% chloride ion carrier IV, 65.2% nitrophenyl octyl ether, 0.4% tetraoctyl ammonium chloride, and the remainder is polyvinyl chloride.

[0032] Example 7: This example is basically the same as Example 1, except that the substrate composition of the chloride ion selective membrane, by weight percentage, includes: 1.2% chloride ion carrier IV, 65.6% nitrophenyl octyl ether, 0.8% tetraoctyl ammonium chloride, and the remainder is polyvinyl chloride.

[0033] Example 8: This example is basically the same as Example 1, except that the base composition of the hydrogen ion selective membrane, by weight percentage, includes: 0.8% hydrogen ion carrier I, 0.3% potassium tetrakis(4-chlorophenyl)borate, 65.3% dioctyl sebacate, and the remainder is polyvinyl chloride.

[0034] Example 9: This example is basically the same as Example 1, except that the base composition of the hydrogen ion selective membrane, by weight percentage, includes: 1.2% hydrogen ion carrier I, 0.7% potassium tetra(4-chlorophenyl)borate, 65.7% dioctyl sebacate, and the remainder is polyvinyl chloride.

[0035] Example 10: This example is basically the same as Example 1, except that the method for preparing the solid contact layer includes the following steps: S1. Add sodium nitrate and silver nitrate to deionized water and stir for 8 minutes to obtain the electrolyte; wherein the mass ratio of sodium nitrate, silver nitrate and deionized water is 1:1.2:12. S2. Pyrrole was added to the electrolyte at room temperature. An electric field was then applied to the electrolyte under heating conditions at a rate of 3°C / min. The initial voltage of the electric field was 0.7V, and the voltage was gradually increased at a rate of 0.15V / min until the electrolyte temperature reached 38°C. Afterward, the voltage of the electric field remained constant. Sodium polystyrene sulfonate was added to the electrolyte. The electrolyte was then placed in an ice bath at 2°C, and ultrasonic waves were applied to it at a power of 100W and a frequency of 22kHz for 25 minutes to obtain a suspension. The amount of pyrrole added accounted for 12% of the total mass of the electrolyte, and the amount of sodium polystyrene sulfonate added accounted for 10% of the total mass of the electrolyte. The electric field was applied using a three-electrode system with a silver sheet as the anode, a platinum sheet as the counter electrode, and an Ag / AgCl electrode rod as the reference electrode. The room temperature was 25°C. S3. Filter and dry the suspension to obtain solid particles; S4. Add solid particles and ethylene glycol to deionized water, stir for 10-15 minutes to obtain a mixture, and drop the mixture onto the conductive layer at a rate of 5 μL. After drying, a solid contact layer is obtained. The mass ratio of solid particles, ethylene glycol and deionized water is 1:0.15:9.

[0036] Example 11: This example is basically the same as Example 1, except that the mass ratio of sodium nitrate, silver nitrate and deionized water is 1:1:10.

[0037] Example 12: This example is basically the same as Example 1, except that the mass ratio of sodium nitrate, silver nitrate and deionized water is 1:1.5:15.

[0038] Example 13: This example is basically the same as Example 1, except that the initial voltage of the electric field is 0.6V, and the voltage of the electric field gradually increases at a rate of 0.1V / min.

[0039] Example 14: This example is basically the same as Example 1, except that the initial voltage of the electric field is 0.8V, and the voltage of the electric field gradually increases at a rate of 0.2V / min.

[0040] Example 15: This example is basically the same as Example 1, except that the amount of pyrrole added accounts for 10% of the total mass of the electrolyte, and the amount of sodium polystyrene sulfonate added accounts for 6% of the total mass of the electrolyte.

[0041] Example 16: This example is basically the same as Example 1, except that the amount of pyrrole added accounts for 15% of the total mass of the electrolyte, and the amount of sodium polystyrene sulfonate added accounts for 12% of the total mass of the electrolyte.

[0042] Example 17: This example is basically the same as Example 1, except that the power of the ultrasound is 80W and the frequency is 20kHz.

[0043] Example 18: This example is basically the same as Example 1, except that the power of the ultrasound is 120W and the frequency is 25kHz.

[0044] Comparative Example 1: Referring to Example 1, the electric field voltage was always kept constant at 0.7V.

[0045] Experimental example: OCP tests were performed on the four working electrodes of the array electrode in Example 1: The test method for the ammonium ion selective electrode is as follows: using ammonium chloride with an ammonia nitrogen concentration of 1 mg / L as the background solution, ammonium chloride with an ammonia nitrogen concentration of 1 g / L is gradually added dropwise to raise the ammonia nitrogen concentration of the solution to 4, 16, 32, and 64 mg / L. The potential of the ammonium ion selective electrode at different concentrations is measured for 30 seconds using an electrochemical workstation. The average value of the potential for 30 seconds is taken as the standard value for each concentration. After data fitting, the fitting equation is obtained as y = 52.5x - 65.05328. From the above fitting equation, it can be seen that the slope of the ammonium ion response in Example 1 is 52.50. The test method for the nitrate ion selective electrode is as follows: using potassium nitrate with a nitrate nitrogen concentration of 1 mg / L as the background solution, potassium nitrate with a nitrate nitrogen concentration of 1 g / L is gradually added dropwise to raise the nitrate nitrogen concentration of the solution to 4, 16, 32, and 64 mg / L. The potential of the nitrate ion selective electrode at different concentrations is measured for 30 seconds using an electrochemical workstation. The average value of the potential over 30 seconds is taken as the standard value for each concentration. After data fitting, the fitting equation is obtained as y = -49.83x - 66.35. From the above fitting equation, it can be seen that the slope of the nitrate ion response in Example 1 is -49.83. The test method for the chloride ion selective electrode is as follows: using potassium chloride with a chloride ion concentration of 1 mg / L as the background solution, potassium chloride with a chloride ion concentration of 10 g / L is gradually added dropwise to raise the chloride ion concentration of the solution to 5, 25, 125, and 625 mg / L. The potential of the chloride ion selective electrode at different concentrations is measured for 30 seconds using an electrochemical workstation. The average value of the potential over 30 seconds is taken as the standard value for each concentration. After data fitting, the fitting equation is obtained as y = -59.22x + 298.57. From the above fitting equation, it can be seen that the chloride ion response slope of Example 1 is -59.22. The test method for the hydrogen ion selective electrode is as follows: using a sodium bicarbonate buffer solution with pH=9 as the background solution, 0.1M hydrochloric acid titrant is gradually added dropwise to lower the pH of the solution to 8, 7, 6, and 5. The potential of the hydrogen ion selective electrode at different concentrations is measured for 30 seconds using an electrochemical workstation. The average value of the potential over 30 seconds is taken as the standard value for each concentration. After data fitting, the fitting equation is obtained as y=53.71x+433.63. From the above fitting equation, it can be seen that the slope of the hydrogen ion response in Example 1 is 53.71. The working electrodes prepared in each embodiment and comparative example were subjected to OCP testing according to the above method to obtain the response slope. Then, the response slope was compared with the theoretical value (59.16 mV / dec for cations and -59.16 mV / dec for anions) to obtain the response deviation. The specific investigation is as follows: Experiment Example 1: Investigating the effect of ammonium ion-selective membrane composition on electrode performance Using Examples 1, 2, and 3 as experimental comparisons, the electrode performance under different ammonium ion-selective membrane compositions was finally obtained, as shown in Table 1 below: Table 1 Electrode performance under different ammonium ion selective membrane compositions

[0046] As shown in Table 1, compared with Examples 1, 2 and 3, the ammonium ion selective electrode of Example 1 has the smallest response deviation, indicating that the ammonium ion selective electrode of Example 1 is the most sensitive to changes in ammonium ion concentration. Therefore, the ammonium ion selective membrane composition selected in Example 1 is optimal.

[0047] Experiment Example 2: Investigating the effect of nitrate ion-selective membrane composition on electrode performance Using Examples 1, 4, and 5 as experimental comparisons, the electrode performance under different nitrate ion-selective membrane compositions was obtained, as shown in Table 2 below: Table 2 Electrode performance under different nitrate ion-selective membrane compositions

[0048] As shown in Table 2, compared with Examples 1, 4, and 5, the nitrate ion selective electrode of Example 1 has the smallest response deviation, indicating that the nitrate ion selective electrode of Example 1 is the most sensitive to changes in nitrate ion concentration. Therefore, the nitrate ion selective membrane composition selected in Example 1 is optimal.

[0049] Experiment Example 3: Investigating the effect of chloride ion selective membrane composition on electrode performance Using Examples 1, 6, and 7 as experimental comparisons, the electrode performance under different chloride ion selective membrane compositions was obtained, as shown in Table 3 below: Table 3 Electrode performance under different chloride ion selective membrane compositions

[0050] As shown in Table 3, compared with Examples 1, 6, and 7, the chloride ion selective electrode of Example 1 has the smallest response deviation, indicating that the chloride ion selective electrode of Example 1 is the most sensitive to changes in chloride ion concentration. Therefore, the chloride ion selective membrane composition selected in Example 1 is optimal.

[0051] Experiment Example 4: Investigating the effect of hydrogen ion selective membrane composition on electrode performance Using Examples 1, 8, and 9 as experimental comparisons, the electrode performance under different hydrogen ion selective membrane compositions was obtained, as shown in Table 4 below: Table 4 Electrode performance under different hydrogen ion selective membrane compositions

[0052] As shown in Table 4, compared with Examples 1, 8, and 9, the hydrogen ion selective electrode of Example 1 has the smallest response deviation, indicating that the hydrogen ion selective electrode of Example 1 is the most sensitive to changes in hydrogen ion concentration. Therefore, the hydrogen ion selective membrane composition selected in Example 1 is optimal.

[0053] Experiment Example 5: Investigating the effect of temperature compensation on electrode performance Using the working electrode from Example 1, OCP tests were performed on ammonium chloride solution with an ammonia nitrogen concentration of 4 mg / L, potassium nitrate solution with a nitrate nitrogen concentration of 2 mg / L, potassium chloride solution with a chloride ion concentration of 12.5 mg / L, and sodium bicarbonate buffer solution with pH=7. The potential of each working electrode at 25°C was recorded as a baseline value. Subsequently, the temperature of each solution was increased, and the potentials of each working electrode at solution temperatures of 30, 35, and 40°C without temperature compensation were recorded, as shown in Table 5. Then, the potentials of each working electrode at solution temperatures of 30, 35, and 40°C with temperature compensation were recorded, as shown in Table 6. The specific investigation is as follows: Table 5. Potentials of each working electrode when temperature compensation is not enabled.

[0054] Table 6. Potentials of each working electrode when temperature compensation is enabled

[0055] As can be seen from the data in Tables 5 and 6, the difference between the electrode potential measured after temperature compensation in Example 1 and the reference value is small. This indicates that the serpentine temperature sensor 34 in Example 1 of this application can effectively reduce the measurement error of the working electrode and improve the measurement accuracy of the working electrode after temperature compensation.

[0056] Experiment Example 6: Investigating the Influence of Solid Contact Layer on Electrode Performance Using Examples 1 and 10 as experimental comparisons, the influence of the solid contact layer on the performance of the working electrode is shown in Table 7 below: Table 7. Influence of solid contact layer on working electrode performance

[0057] As shown in Table 7, compared with Example 10, Example 10 has a smaller working electrode response deviation, indicating that the working electrode of Example 10 has higher detection sensitivity. This shows that the solid contact layer of Example 10 can improve the detection sensitivity of the electrode. Therefore, the solid contact layer prepared by the method of Example 10 has better performance.

[0058] Experiment Example 7: Investigating the effect of electrolyte composition on electrode performance Using Examples 10, 11, and 12 as comparative experiments, the performance of the working electrode under different electrolyte compositions is shown in Table 8 below: Table 8 Performance of working electrodes under different electrolyte compositions

[0059] As shown in Table 8, compared with Examples 10, 11, and 12, Example 10 has the smallest response deviation for each working electrode, indicating that the working electrode of Example 10 has the highest detection sensitivity. This may be because the silver ions in the electrolyte composition of Example 10 can fully coordinate with polypyrrole, so the electrolyte composition selected in Example 10 is optimal.

[0060] Experiment Example 8: Investigating the Influence of Electric Field Parameters on Electrode Performance Using Examples 10, 13, and 14, as well as Comparative Example 1, as experimental comparisons, the performance of the working electrode under different electric field parameters is shown in Table 9 below: Table 9. Influence of Working Electrode Performance under Different Electric Field Parameters

[0061] As shown in Table 9, compared with Examples 10, 13, and 14, Example 10 has the smallest response deviation for each working electrode, indicating that the working electrode of Example 10 has the highest detection sensitivity. This may be because pyrrole can fully polymerize under the electric field parameters of Example 10, so the electric field parameters selected in Example 10 are optimal.

[0062] Compared with Comparative Example 1, Example 10 shows that after the electric field voltage is kept constant, the response deviation of each working electrode increases. This may be because the silver ions in the electrolyte cannot fully coordinate with the polypyrrole. Therefore, the electric field parameters selected in Example 10 are better.

[0063] Experiment Example 9: Investigating the effect of the amount of pyrrole and sodium polystyrene sulfonate added on electrode performance. Using Examples 10, 15, and 16 as experimental comparisons, the working electrode performance under different addition amounts of pyrrole and sodium polystyrene sulfonate is shown in Table 10 below: Table 10 Effect of different addition amounts of pyrrole and sodium polystyrene sulfonate on the performance of the working electrode

[0064] As shown in Table 10, compared with Examples 10, 15, and 16, Example 10 has the smallest response deviation for each working electrode, indicating that the working electrode of Example 10 has the highest detection sensitivity. This may be because under the electric field parameters of Example 10, the amount of pyrrole and sodium polystyrene sulfonate added allows the sodium polystyrene sulfonate to fully dope the polypyrrole chain. Therefore, the amount of pyrrole and sodium polystyrene sulfonate added selected in Example 10 is optimal.

[0065] Experiment Example 10: Investigating the Influence of Ultrasonic Processing Parameters on Electrode Performance Using Examples 10, 17, 18 and Comparative Example 2 as experimental comparisons, the performance of the working electrode under different ultrasonic processing parameters is shown in Table 11 below: Table 11 Influence of working electrode performance under different ultrasonic processing parameters

[0066] As shown in Table 11, compared with Examples 10, 17 and 18, Example 10 has the smallest response deviation of each working electrode, indicating that the working electrode of Example 10 has the highest detection sensitivity. This may be because the solid particle composition is uniform under the ultrasonic processing parameters of Example 10, so the ultrasonic processing parameters selected in Example 10 are optimal.

Claims

1. An electrochemical array electrode for comprehensive online water quality monitoring, characterized in that, It includes a base layer (3), and a conductive wiring layer (1) and an insulating shield layer (2) arranged sequentially from top to bottom on the base layer (3). Electrodes are provided on the base layer (3) below the insulating shield layer (2). The electrodes include a plurality of horizontally arranged working electrodes (33) and L-shaped counter electrodes (32) and reference electrodes (31) arranged sequentially from top to bottom below the working electrodes (33). The conductive wiring layer (1) is provided with pins (11) corresponding to each electrode. The pins (11) are electrically connected to the corresponding electrodes through wires (21) provided in the insulating shield layer (2).

2. The electrochemical array electrode for comprehensive online water quality monitoring according to claim 1, characterized in that, The base layer is provided with a serpentine temperature sensor (34) for temperature compensation of the working electrode (33). The conductive wiring layer (1) is provided with a pin (11) corresponding to the serpentine temperature sensor (34). The pin (11) is electrically connected to the serpentine temperature sensor (34) through a wire (21) provided in the insulating shielding layer (2).

3. The electrochemical array electrode for comprehensive online water quality monitoring according to claim 1, characterized in that, The conductive wiring layer (1) is made by screen printing conductive silver paste or carbon paste on the substrate layer (3), and the thickness of the conductive wiring layer (1) is 8~12µm.

4. The electrochemical array electrode for comprehensive online water quality monitoring according to claim 1, characterized in that, The insulating shielding layer (2) is made by brushing insulating oil onto the base layer (3) and curing it. The thickness of the insulating shielding layer (2) is 30~40µm.

5. An electrochemical array electrode for comprehensive online water quality monitoring according to claim 1, characterized in that, The working electrode (33) consists of a conductive layer, a solid contact layer disposed on the conductive layer, and an ion-selective film disposed on the solid contact layer; wherein the thickness of the conductive layer is 5~10µm, the thickness of the solid contact layer is 2~6µm, and the thickness of the ion-selective film is 5~10µm.

6. An electrochemical array electrode for comprehensive online water quality monitoring according to claim 5, characterized in that, The ion-selective membrane is any one of ammonium ion-selective membrane, nitrate ion-selective membrane, chloride ion-selective membrane, or hydrogen ion-selective membrane.

7. An electrochemical array electrode for comprehensive online water quality monitoring according to claim 6, characterized in that, The ion-selective membrane is prepared by dissolving 0.95~1.05 mg of the substrate component in 5 μL of tetrahydrofuran to prepare a substrate solution, and then drop-coating the substrate solution onto the surface of the solid contact layer. The substrate components of the ammonium ion selective membrane, by weight percentage, include: 6.7~7.1% non-viable bacteria, 92.2~92.6% nitrophenyl octyl ether, 0.5~0.9% potassium tetra(4-chlorophenyl)borate, and the balance being polyvinyl chloride; The substrate composition of the nitrate ion-selective membrane, by weight percentage, includes: 5.0~5.4% nitrate ion carrier VI, 46.9~47.3% dibutyl phthalate, 0.4~0.8% tetraoctyl ammonium chloride, and the balance being polyvinyl chloride; The substrate composition of the chloride ion selective membrane, by weight percentage, includes: 0.8~1.2% chloride ion carrier IV, 65.2~65.6% nitrophenyl octyl ether, 0.4~0.8% tetraoctyl ammonium chloride, and the balance being polyvinyl chloride; The substrate composition of the hydrogen ion selective membrane, by weight percentage, includes: 0.8~1.2% hydrogen ion carrier I, 0.3~0.7% potassium tetra(4-chlorophenyl)borate, 65.3~65.7% dioctyl sebacate, and the balance being polyvinyl chloride.

8. An electrochemical array electrode for comprehensive online water quality monitoring according to claim 5, characterized in that, The solid contact layer is prepared by: dropping a PEDOT:PSS aqueous dispersion onto a conductive layer and drying it to obtain a solid contact layer.

9. An electrochemical array electrode for comprehensive online water quality monitoring according to claim 5, characterized in that, The method for preparing the solid contact layer includes the following steps: S1. Add sodium nitrate and silver nitrate to deionized water and stir for 5-10 minutes to obtain the electrolyte; wherein the mass ratio of sodium nitrate, silver nitrate and deionized water is 1:1-1.5:10-15. S2. Add pyrrole to the electrolyte at room temperature, then apply an electric field to the electrolyte while heating. The heating rate is 2-4℃ / min, the initial voltage of the electric field is 0.6-0.8V, and the voltage of the electric field is gradually increased at a rate of 0.1-0.2V / min until the electrolyte temperature reaches 35-40℃. After that, the voltage of the electric field becomes constant. Add sodium polystyrene sulfonate to the electrolyte, then place the electrolyte in an ice bath at 0-5℃ and apply ultrasound to the electrolyte. The power of the ultrasound is 80-120W, the frequency is 20-25kHz, and the ultrasonic treatment is carried out for 20-30 minutes to obtain a suspension. The amount of pyrrole added accounts for 10-15% of the total mass of the electrolyte, and the amount of sodium polystyrene sulfonate added accounts for 6-12% of the total mass of the electrolyte. S3. Filter and dry the suspension to obtain solid particles; S4. Add solid particles and ethylene glycol to deionized water, stir for 10-15 minutes to obtain a mixture, drop the mixture onto the conductive layer, and dry to obtain a solid contact layer; wherein, the mass ratio of solid particles, ethylene glycol and deionized water is 1:0.1-0.2:8-10.

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