Water quality heavy metal on-line monitoring system, device and method based on boron-doped diamond thin film electrode

Abstract

This invention discloses an online monitoring system, equipment, and method for heavy metals in water quality based on boron-doped diamond thin-film electrodes, belonging to the field of environmental monitoring technology. The online monitoring method of this invention includes electrode cleaning and activation, pre-coating, heavy metal enrichment, leaching and detection, and electrode regeneration, and is equipped with a fully automated online monitoring system. The online monitoring system includes a control module, flow path unit, sensing and measurement unit, signal processing module, and data processing terminal, etc. This invention achieves highly sensitive, highly stable, long-cycle, maintenance-free continuous automatic monitoring of multiple heavy metal ions in water by periodically executing the fully automated processes of cleaning, coating, enrichment, and leaching through an automated online monitoring system. This completely solves the industry problems of easy contamination, instability, and frequent maintenance of traditional electrodes in online monitoring, significantly improving monitoring reliability and reducing operation and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring technology, specifically to an online water quality heavy metal monitoring system, equipment, and method based on boron-doped diamond thin-film electrodes. Background Technology

[0002] Electrochemical anodic stripping voltammetry is considered one of the ideal technologies for online monitoring of heavy metal ions due to its high sensitivity and portable equipment. Its core lies in the performance of the working electrode. In recent years, boron-doped diamond electrodes have attracted widespread attention in this field due to their excellent properties such as wide potential window, low background current, and high physicochemical stability. In its application to heavy metal detection, there are two main methods: one is for the detection of specific heavy metals, and the other is for multi-element detection based on electrode modification technology.

[0003] Regarding the first approach, Chinese patent document CN121431620A provides a method for online monitoring of the heavy metal thallium. This method, targeting a specific system of thallium ions and a boron-doped diamond electrode, has optimized a complete set of parameters through extensive experiments. These parameters include: anodic / cathode polarization pretreatment with a specific concentration of nitric acid solution at a specific potential and time; a specific concentration of HAc-NaAc as the supporting electrolyte; and optimized enrichment and square-wave dissolution parameters. This approach successfully solves the selectivity and sensitivity issues when applying a BDD electrode to trace thallium detection, achieving highly sensitive (detection limit 0.1 ppb) and highly stable detection of thallium ions, representing an advanced level of high-performance detection methods for a single specific heavy metal. However, this solution faces inherent limitations when integrated into online monitoring systems capable of long-term unattended operation: 1. Limited functionality: Its entire parameter system (such as support for electrolytes and enrichment potential) is tailored to the physicochemical properties of thallium ions, making it difficult to directly apply to the detection of other heavy metal ions such as lead, cadmium, and copper; to monitor multiple heavy metals, a completely different detection process with different parameters is required, resulting in a complex and inefficient system; 2. Lack of a long-term maintenance mechanism: The clean and activated electrode surface obtained through polarization pretreatment will inevitably become contaminated and passivated due to the adsorption of organic matter, the formation of an oxide layer, or inorganic precipitation during long-term continuous contact with actual complex water bodies, leading to decreased sensitivity and signal drift; no solution is provided for restoring electrode performance online without interrupting monitoring or human intervention, which is precisely the core challenge that must be overcome to achieve engineered and commercialized online monitoring equipment.

[0004] Regarding the second type, Chinese patent document CN101975811A provides an electrochemical sensor for on-site trace heavy metal detection. It forms an environmentally friendly bismuth-based composite electrode by pre-plating or co-plating a bismuth film on the surface of conventional electrodes (such as glassy carbon electrodes or gold electrodes), thereby enabling the detection of various heavy metals such as lead, cadmium, and copper. However, there are significant obstacles to directly applying such modification techniques to boron-doped diamond electrodes and integrating them into online monitoring systems: 1. Interface stability and compatibility issues: The advantage of BDD electrodes lies in their intrinsic, stable "bare" surface. Introducing additional modification layers such as bismuth films onto them completely alters the electrode / solution interface properties. Existing technologies do not provide solutions on how to ensure a strong bond between the additional modification layer and the BDD substrate under long-term electrochemical operation, or how to prevent the modification layer from masking the advantages of the BDD electrode's wide potential window. 2. Online regeneration challenges of modification layers: Like bare BDD electrodes, modification layers (such as bismuth films) will also become contaminated and worn down after long-term use. Although the patent document solves the problem of "how to form a bismuth film for detection," it does not address how to automatically and periodically regenerate a modification layer with consistent performance in online continuous operation scenarios to maintain long-term monitoring stability. If manual recoating is required after each detection, the meaning of online automatic monitoring is completely lost.

[0005] In summary, existing online monitoring solutions based on boron-doped diamond electrodes cannot simultaneously meet the requirements of inheriting the intrinsic advantages of BDD electrodes, achieving broad-spectrum detection of multiple heavy metal ions, and maintaining high performance and stability of the electrodes over a long period without human intervention through embedded automation mechanisms, thus truly satisfying the stringent requirements of on-site, continuous, and long-term online monitoring. Summary of the Invention

[0006] This invention addresses the technical problems of existing boron-doped diamond electrodes with modified layers, which, while achieving broad-spectrum detection of various heavy metal ions, suffer from significant degradation in stability, sensitivity, and reliability during long-term monitoring, as well as high maintenance costs. The aim is to provide a water quality heavy metal online monitoring system, equipment, and method based on boron-doped diamond thin-film electrodes. This automated online monitoring system periodically executes a fully automatic process of cleaning, coating, enrichment, and leaching, achieving highly sensitive, highly stable, long-term, maintenance-free continuous automatic monitoring of various heavy metal ions in water. This completely solves the industry problems of traditional electrodes being prone to contamination, instability, and frequent maintenance in online monitoring, significantly improving monitoring reliability and reducing operation and maintenance costs.

[0007] This invention is achieved through the following technical solution:

[0008] The first objective of this invention is to provide a method for online monitoring of heavy metals in water quality based on boron-doped diamond thin-film electrodes, comprising the following steps:

[0009] S1. Electrode cleaning and activation: Place the electrochemical sensor in a 5%-20% nitric acid solution, and apply the first anodic potential and the first cathode potential in sequence to complete the redox cleaning of the electrode surface;

[0010] S2, Pre-coating: The electrochemical sensor obtained in S1 is placed in a Bi-containing... 3+ Hg 2+ or Sb 3+ In the electrolyte, a constant cathode deposition potential is applied, and a modification layer is formed on the BDD working electrode of the electrochemical sensor by electrodeposition for 30-500 seconds using a chronoamperometry method.

[0011] S3, Heavy metal enrichment: The electrochemical sensor obtained in S2 is exposed to the water sample to be tested, and a second cathode potential is applied under stirring conditions to enrich the target heavy metal ions on the surface of the BDD working electrode to form heavy metal elements.

[0012] S4. Dissolution and Detection: Apply a square wave voltage to the BDD working electrode and scan towards the anode. Record the potential-current curve during the dissolution process. Quantify the concentration of the target heavy metal ions by the dissolution peak current.

[0013] S5. Electrode regeneration: Return to step S1 and begin the next monitoring cycle.

[0014] Furthermore, in step S1, the first anode potential is +0.5 V to +3.5 V vs. SCE, lasting for 10-500 seconds.

[0015] Furthermore, in step S1, the first cathode potential is -0.5 V to -3.5 V vs. SCE, lasting for 10-500 seconds.

[0016] Furthermore, in step S2, the cathode deposition potential is -0.5 V to -1.5 V vs. SCE, lasting for 30-500 seconds.

[0017] Furthermore, in step S3, the second cathode potential is -0.9 V to -1.5 V vs. SCE, lasting for 180-900 seconds.

[0018] A second objective of this invention is to provide an online water quality heavy metal monitoring system based on a boron-doped diamond thin-film electrode, used in the aforementioned method, comprising:

[0019] The control module is connected to the control flow path unit, the signal processing module, and the data processing terminal.

[0020] Flow path unit, used to introduce the water sample to be tested;

[0021] The sensing and measurement unit integrates an electrochemical sensor for detecting the water sample and outputting a detection signal;

[0022] The signal processing module is used to receive and condition the detection signal, and output the conditioned data to the control module, which then sends it to the data processing terminal.

[0023] The data processing terminal is used to process conditioning data, identify dissolution peaks, and calculate the target heavy metal ion concentration.

[0024] Furthermore, the electrochemical sensor includes a BDD working electrode, a reference electrode, and an auxiliary electrode. The BDD working electrode includes a conductive substrate and a boron-doped diamond film grown on the conductive substrate. The conductive substrate is any one of silicon, titanium, tantalum, niobium, tungsten, graphite, and molybdenum.

[0025] Furthermore, the boron doping concentration of the boron-doped diamond film is 500-50000 ppm.

[0026] Furthermore, a uniform bismuth film, mercury film, or antimony film is formed on the surface of the BDD working electrode through in-situ electrodeposition, preferably a bismuth film.

[0027] A third object of the present invention is to provide an electronic device, including a memory and a processor;

[0028] A memory for storing computer programs, the computer programs including program instructions;

[0029] A processor is configured to execute the program instructions to cause the electronic device to perform the steps of the aforementioned method.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] 1. This invention introduces BDD electrodes into online automatic water quality monitoring. Their exceptional physicochemical stability and wide potential window fundamentally solve the core problems of traditional electrodes, such as easy corrosion and passivation. At the same time, it innovatively integrates automated in-situ electrode cleaning, pre-coating process, and automatic electrode regeneration cycle, realizing highly sensitive, highly stable, and long-term maintenance-free continuous automatic monitoring of trace heavy metal ions in water. The system maintenance cycle is significantly extended from the traditional several days to a week to more than 30 days, significantly reducing operation and maintenance costs and reliance on professional personnel.

[0032] 2. This invention employs an alternating polarization cleaning method of "anodine-cathode" and pre-deposits a modification film on the surface of the BDD working electrode. Combined with the automatic electrode regeneration cycle operation, the system achieves automated in-situ self-maintenance without disassembling the electrode or using toxic reagents, making it perfectly suited for unattended online monitoring scenarios.

[0033] 3. The online monitoring method of the present invention has high sensitivity for a variety of heavy metal ions such as thallium (Tl), copper (Cu), zinc (Zn), tin (Sn), nickel (Ni), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), antimony (Sb) and mercury (Hg), with a detection limit of up to 0.01 μg / L and good reproducibility (RSD usually <5%). Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0035] Figure 1 This is a schematic diagram of the online monitoring system structure of the present invention;

[0036] Figure 2 This is a comparison of the signal stability of the BDD electrode and the glassy carbon electrode during 15 days of continuous operation in Experiment Example 1 of this invention;

[0037] Figure 3 In Experiment 2 of this invention, the same contaminated electrode was tested before and after cleaning using the method of this invention at a concentration of 5 μg / L. + Comparison of dissolution voltammetry curves;

[0038] Figure 4 This is an example from Experiment 4 of the present invention, showing the effect of pre-plated bismuth films at different bismuth concentrations on 5 μg / L Tl. + Comparison of detected peak current and stability (RSD);

[0039] Figure 5 This is the standard curve of Tl⁺ in the concentration range of 0-10 μg / L in Experimental Example 4 of this invention;

[0040] Figure 6 In Experiment 4 of this invention, the electrode was stored for different number of days, and the effect of 5 μg / L Tl was observed. + Graph showing the long-term stability of the measured peak current.

[0041] The attached diagram shows the markings and corresponding component names:

[0042] 1-System power supply, 2-Control module, 3-Flow path unit, 4-Sensing and measurement unit, 5-Signal processing module, 6-Data processing terminal, 7-Touch screen, 8-Data acquisition instrument or cloud. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0044] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art.

[0045] The "scope" disclosed in this invention is defined in the form of a lower limit and an upper limit. A given scope is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific scope. The scope defined in this way can include or exclude end values, and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a scope.

[0046] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0047] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0048] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other substances not listed may also be included, or that only the listed substances may be included.

[0049] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0050] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0051] It should be noted that, unless otherwise specified, the experimental methods used in the embodiments are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0052] Example 1

[0053] A method for online monitoring of heavy metals in water quality based on boron-doped diamond thin-film electrodes includes the following steps:

[0054] S1. Electrode cleaning and activation: Place the electrochemical sensor in a 5%-20% nitric acid solution, and sequentially apply the first anodic potential (+0.5 V to +3.5 V vs. SCE, lasting 10-500 seconds) and the first cathode potential (-0.5 V to -3.5 V vs. SCE, lasting 10-500 seconds) to complete the redox cleaning of the electrode surface;

[0055] S2, Pre-coating: The electrochemical sensor obtained in S1 is placed in a Bi-containing... 3+ Hg 2+ or Sb 3+ In an electrolyte (electrolyte composition such as bismuth nitrate solution and sodium acetate solution, mercuric nitrate solution and sodium acetate solution, antimony trichloride solution and sodium acetate solution), a constant cathode deposition potential (-0.5 V to -1.5 V vs. SCE) is applied, and a modification layer is formed on the BDD working electrode of the electrochemical sensor by chronoamperometry for 30-500 seconds.

[0056] S3, Heavy Metal Enrichment: The electrochemical sensor obtained in S2 is exposed to the water sample to be tested. Under stirring conditions, a second cathode potential (-0.9 V to -1.5 V vs. SCE, lasting 180-900 seconds) is applied to enrich the target heavy metal ions on the surface of the BDD working electrode, forming heavy metal elements.

[0057] S4. Dissolution and Detection: Apply a square wave voltage to the BDD working electrode and scan towards the anode. Record the potential-current curve during the dissolution process. Quantify the concentration of the target heavy metal ions by the dissolution peak current.

[0058] S5. Electrode regeneration: Return to step S1 and begin the next monitoring cycle.

[0059] This invention introduces BDD electrodes into online automatic water quality monitoring. Their exceptional physicochemical stability and wide potential window fundamentally solve the core problems of traditional electrodes, such as easy corrosion and passivation. At the same time, it innovatively integrates automated in-situ electrode cleaning, pre-coating process, and automatic electrode regeneration cycle, realizing highly sensitive, highly stable, and long-term maintenance-free continuous automatic monitoring of trace heavy metal ions in water. The system maintenance cycle is significantly extended from the traditional several days to a week to more than 30 days, significantly reducing operation and maintenance costs and reliance on professional personnel.

[0060] This invention employs an alternating polarization cleaning method of "anode-cathode" and pre-deposits a modification film on the surface of the BDD working electrode. Combined with the automatic electrode regeneration cycle operation, the system achieves automated in-situ self-maintenance without disassembling the electrode or using toxic reagents, making it perfectly suited for unattended online monitoring scenarios.

[0061] The online monitoring method of the present invention has high sensitivity to a variety of heavy metal ions such as thallium (Tl), copper (Cu), zinc (Zn), tin (Sn), nickel (Ni), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), antimony (Sb) and mercury (Hg), with a detection limit of up to 0.01 μg / L and good reproducibility (RSD usually <5%).

[0062] Example 2

[0063] A water quality heavy metal online monitoring system based on boron-doped diamond thin-film electrodes, used in the method of Example 1, such as... Figure 1 As shown, it includes a system power supply 1, a control module 2, a flow path unit 3, a sensing and measurement unit 4, a signal processing module 5, a data processing terminal 6, a touch screen 7, and a data acquisition instrument or cloud 8;

[0064] The system power supply 1 shown provides power to the online monitoring system;

[0065] The control module 2 is connected to the data processing terminal 6, the signal processing module 5, and the flow path unit 3. It is used to control the operation of the data processing terminal 6, the signal processing module 5, and the flow path unit 3, send instructions to each execution module, and coordinate the working sequence.

[0066] The flow path unit 3 is used to introduce the water sample to be tested, to measure the water sample to be tested, to perform pretreatment and digestion of the water sample to be tested, and to switch the flow path in the monitoring stage.

[0067] The sensing and measurement unit 4 integrates an electrochemical sensor for electrochemical processing and detection of the water sample to be tested, and outputs the detection signal to the signal processing module 5.

[0068] The signal processing module 5 is used to receive the detection signal and condition it, and send the conditioned data to the control module 2, which then sends it to the data processing terminal 6.

[0069] The data processing terminal 6 is used to process the conditioning data, identify dissolution peaks and calculate the target heavy metal ion concentration to obtain monitoring data.

[0070] The touchscreen 7 provides human-computer interaction, data storage, and data communication functions for monitoring data;

[0071] The data acquisition instrument or cloud-based system remotely transmits all data from the monitoring system.

[0072] The electrochemical sensor includes a BDD working electrode, a reference electrode, and an auxiliary electrode. The BDD working electrode includes a conductive substrate and a boron-doped diamond film grown on the conductive substrate. The conductive substrate is any one of silicon, titanium, tantalum, niobium, tungsten, graphite, and molybdenum.

[0073] Specifically, the boron doping concentration of the boron-doped diamond film is 500-50000 ppm; a uniform bismuth film, mercury film or antimony film is formed on the surface of the BDD working electrode by in-situ electrodeposition, preferably a bismuth film.

[0074] The online monitoring system of this invention enables fully automated industrial operation. The system maintenance cycle has been significantly extended from the traditional several days to a week to more than 30 days, significantly reducing operation and maintenance costs and reliance on professional personnel. It achieves automated in-situ maintenance without disassembling electrodes or using toxic reagents, perfectly adapting to unattended online monitoring scenarios. It can be used for highly sensitive, highly stable, long-term maintenance-free continuous automatic monitoring of various heavy metal ions such as thallium (Tl), copper (Cu), zinc (Zn), tin (Sn), nickel (Ni), lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), antimony (Sb), and mercury (Hg).

[0075] Example 3

[0076] This embodiment provides a computer device, including a memory, a processor, a communication interface, and at least one communication bus for connecting the processor, the memory, and the communication interface. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the method described in Embodiment 1. The computer device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The computer device can interact with a user via a keyboard, mouse, remote control, touchpad, or voice control device. The memory includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (PROM), or portable read-only memory (CD-ROM), and is used for related instructions and data. The processor can be one or more CPUs; if the processor is a single CPU, it can be a single-core CPU or a multi-core CPU. The communication interface is used to receive and send data.

[0077] Experimental Example 1

[0078] Sensor Long-Term Stability Comparison Test

[0079] Test System: Two identical test systems were constructed according to the method of this invention, using a BDD electrode and a traditional glassy carbon electrode as working electrodes, respectively. The specific test parameters of the systems are as follows:

[0080] In S1, 10% nitric acid solution, polarization at 2.5V for 60s, polarization at -2V for 60s;

[0081] S2, in bismuth nitrate-sodium acetate solution, -1.4V, 200s;

[0082] S3. In the sample and the acetic acid-sodium acetate solution, enrich at -1.2V for 600s, then let stand for 60s;

[0083] S4. Dissolved using square wave voltammetry (SWV).

[0084] Test method: Prepare 5 μg / L Tl + The standard solution was continuously monitored using a simulated method, with measurements taken every 6 hours. The results are as follows: Figure 2 As shown.

[0085] from Figure 2 It can be seen that the signal fluctuation range of the BDD electrode system used in this invention is within ±5% within 15 days; while the glassy carbon electrode system shows significant signal attenuation starting from the 3rd day and attenuation of more than 50% by the 7th day, which cannot meet the monitoring requirements. This proves the unparalleled stability advantage of the BDD electrode in long-term online monitoring.

[0086] Experimental Example 2

[0087] In-situ polarization cleaning effect verification

[0088] The BDD working electrode was immersed in a high-concentration humic acid solution for 24 hours to simulate severe contamination. It was then cleaned using step S1 of this invention: in a 10% nitric acid solution, it was first anolyzed at +2.5 V (vs. SCE) for 60 seconds, and then cathodically polarized at -2.0 V (vs. SCE) for 60 seconds. Before and after cleaning, Tl (5 μg / L) was measured. + Standard solution. Results as follows: Figure 3 As shown, normal test data refers to the data that has passed the complete test process described above, from steps S1 to S5.

[0089] from Figure 3 As can be seen, the dissolution peak of the contaminated electrode almost disappeared, while after cleaning using the method of this invention, its peak current recovered to more than 98% of that of a fresh electrode. This demonstrates the high efficiency of the cleaning method.

[0090] Experimental Example 3

[0091] Thallium (Tl) in actual surface water samples + Monitoring

[0092] The system of this invention (specific parameters are shown in Experiment 1) was used to monitor water samples from a river section online for 7 days, and the results were compared with those obtained by daily sampling and testing using laboratory ICP-MS. The instrument was set to automatically complete a "cleaning-coating-measurement" cycle every 4 hours. As shown in Table 1, the total thallium concentration measured by the system of this invention fluctuated within the range of 0.042–0.057 μg / L, showing good consistency with the ICP-MS results (0.044–0.057 μg / L) (relative error <15%), and no manual maintenance was required during the 7 days, with a data acquisition rate >98%. This fully demonstrates the practicality and reliability of this invention.

[0093] Table 1. Results of System Field Verification Experiment

[0094]

[0095] Experiment Example 4

[0096] Optimization and stability verification of key process parameters

[0097] This embodiment optimizes core process parameters based on systematic experimental data and verifies long-term stability.

[0098] Optimization of bismuth film pre-coating conditions: The effect of bismuth ion concentration on the sensitivity and stability of thallium detection was systematically investigated. Results showed that at 75 ppm Bi... 3+At the specified concentration, deposition for 200 seconds at -1.4 V (vs. SCE) resulted in a concentration of 5 μg / L Tl. + The detection signal is the strongest and has the best reproducibility (RSD < 5%). Optimization conditions are as follows: Figure 4 As shown.

[0099] Method linearity and lower limit of quantitation: Under optimized conditions, for Tl + Detection was performed in the range of 0-10 μg / L, and a good linear standard curve was obtained, such as... Figure 5 As shown, the linear equation is y = 1.3593x + 0.1106, and the correlation coefficient R0 is... 2 = 0.9993. Calculated based on 10 times the standard deviation of 10 blanks, the method's lower limit of quantitation (LOQ) is as low as 0.03 μg / L, far exceeding conventional requirements.

[0100] Long-term stability verification: After storing the optimized electrode in air for different numbers of days, the Tl concentration at 5 μg / L was measured. + The result is as follows Figure 6 As shown, even after 7 days of storage, the RSD of the measured signal remains below 5%, demonstrating the excellent resistance to environmental interference and long-term stability of this method.

[0101] Experimental Example 5

[0102] Feasibility verification of mercury film or antimony film as alternatives

[0103] This experimental example uses a mercury membrane or an antimony membrane for verification. The membrane contains 10 ppm Hg. 2+ Or 300ppm Sb 3+ In a sodium acetate-acetic acid medium, mercury or antimony films were deposited for 180 or 240 seconds at -1.0 V (vs. SCE) to form films. Subsequently, Pb... 2+ Cd 2+ The detection limit can also reach the sub-ppb level, proving that the BDD electrode substrate is also suitable for traditional mercury film or antimony film systems, thus expanding the application scope of the present invention.

[0104] Finally, it should be noted that the above specific embodiments are only used to describe the purpose, technical solution, and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation of the present invention and is not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the foregoing specific embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions or improvements can be made to some or all of the technical features. These modifications, equivalent substitutions, and improvements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for online monitoring of heavy metals in water quality based on boron-doped diamond thin-film electrodes, comprising the following steps: S1. Electrode cleaning and activation: Place the electrochemical sensor in a 5%-20% nitric acid solution, and apply the first anodic potential and the first cathode potential in sequence to complete the redox cleaning of the electrode surface; S2, Pre-coating: The electrochemical sensor obtained in S1 is placed in a Bi-containing... 3+ Hg 2+ or Sb 3+ In the electrolyte, a constant cathode deposition potential is applied, and a modification layer is formed on the BDD working electrode of the electrochemical sensor by electrodeposition for 30-500 seconds using a chronoamperometry method. S3, Heavy metal enrichment: The electrochemical sensor obtained in S2 is exposed to the water sample to be tested, and a second cathode potential is applied under stirring conditions to enrich the target heavy metal ions on the surface of the BDD working electrode to form heavy metal elements. S4. Dissolution and Detection: Apply a square wave voltage to the BDD working electrode and scan towards the anode. Record the potential-current curve during the dissolution process. Quantify the concentration of the target heavy metal ions by the dissolution peak current. S5. Electrode regeneration: Return to step S1 and begin the next monitoring cycle.

2. The method for online monitoring of heavy metals in water quality based on a boron-doped diamond thin-film electrode according to claim 1, characterized in that, In step S1, the first anode potential is +0.5 V to +3.5 V vs. SCE, lasting for 10-500 seconds.

3. The method for online monitoring of heavy metals in water quality based on a boron-doped diamond thin-film electrode according to claim 1, characterized in that, In step S1, the first cathode potential is -0.5 V to -3.5 V vs. SCE for 10-500 seconds.

4. The method for online monitoring of heavy metals in water quality based on a boron-doped diamond thin-film electrode according to claim 1, characterized in that, In step S2, the cathode deposition potential is -0.5 V to -1.5 V vs. SCE for 30-500 seconds.

5. The method for online monitoring of heavy metals in water quality based on a boron-doped diamond thin-film electrode according to claim 1, characterized in that, In step S3, the second cathode potential is -0.9 V to -1.5 V vs. SCE for 180-900 seconds.

6. A water quality heavy metal online monitoring system based on boron-doped diamond thin-film electrodes, characterized in that, The method used in any one of claims 1-5 includes: The control module (2) is connected to the control flow path unit (3), the signal processing module (5), and the data processing terminal (6); Flow path unit (3) is used to introduce the water sample to be tested; The sensing and measurement unit (4) integrates an electrochemical sensor for detecting the water sample to be tested and outputting a detection signal; The signal processing module (5) is used to receive the detection signal and condition it, and output the conditioned data to the control module (2), which then sends it to the data processing terminal (6). The data processing terminal (6) is used to process conditioning data, identify dissolution peaks and calculate the target heavy metal ion concentration.

7. The online water quality heavy metal monitoring system based on boron-doped diamond thin-film electrode according to claim 6, characterized in that, The electrochemical sensor includes a BDD working electrode, a reference electrode, and an auxiliary electrode. The BDD working electrode includes a conductive substrate and a boron-doped diamond film grown on the conductive substrate. The conductive substrate is any one of silicon, titanium, tantalum, niobium, tungsten, graphite, and molybdenum.

8. The online water quality heavy metal monitoring system based on boron-doped diamond thin-film electrode according to claim 7, characterized in that, The boron doping concentration of the boron-doped diamond film is 500-50000 ppm.

9. The online water quality heavy metal monitoring system based on boron-doped diamond thin-film electrode according to claim 7, characterized in that, A uniform bismuth film, mercury film, or antimony film is formed on the surface of the BDD working electrode through in-situ electrodeposition.

10. An electronic device, characterized in that, Including memory and processor; A memory for storing computer programs, the computer programs including program instructions; A processor for executing the program instructions to cause the electronic device to perform the steps of the method as described in any one of claims 1 to 5.

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