Heavy metal online in-situ detection device and method

Abstract

The invention relates to the technical field of water quality monitoring and electrochemical detection, in particular to a heavy metal online in-situ detection device and method. The detection device comprises a water sample detection bin and a control end, a detection sensor and a water level detection probe are arranged in the water sample detection bin, and the detection sensor and the water level detection probe are respectively communicated with the control end; the detection sensor comprises a detection bin shell, an electrode chamber A and an electrode chamber B, an auxiliary electrode is arranged in the electrode chamber A, and a reference electrode, a working electrode, a stirrer and a pH probe are arranged in the electrode chamber B; under the control of the control end, the electrode chamber A supplies H < + > to the electrode chamber B, an optimal buffer detection environment is created for heavy metals in the electrode chamber B, and the heavy metals in a water sample entering the water sample detection bin can enter the electrode chamber B to be enriched and dissolved out. The detection device solves the technical bottleneck that a traditional electrochemical method cannot monitor heavy metal ions in underground water on line, realizes real-time on-line monitoring of the heavy metal ions in water, and ensures high sensitivity and high precision of heavy metal ion detection.

Description

Technical Field

[0001] The present invention relates to the technical field of water quality monitoring and electrochemical detection, and in particular to an online in-situ detection device and method for heavy metals. Background Art

[0002] Groundwater is one of the most important water resources on Earth and is widely used in agricultural irrigation, industrial production, and drinking water. The quality of groundwater is directly related to the health of the ecological environment and the safety of human life. However, with the acceleration of industrialization and urbanization, a large amount of industrial wastewater, agricultural fertilizers, pesticides and other pollutants have penetrated into the groundwater layer through the surface, resulting in an increasingly serious problem of heavy metal pollution in groundwater.

[0003] However, in the process of groundwater monitoring, many technical problems such as high spatiotemporal variation and sampling difficulties are faced. At present, electrochemical methods have been widely used in heavy metal ion detection due to their advantages such as high sensitivity and fast response speed, but traditional electrochemical detection methods all adopt the "underground extraction sampling-ground field detection" technical route, which is difficult to meet the needs of real-time and rapid online monitoring. The reason is that the groundwater heavy metal ions need to add buffer solution during the detection process to create a suitable monitoring environment pH. Therefore, the development of a new groundwater heavy metal monitoring device that can truly solve this problem not only has urgent research value, but also has good economic benefits and industrial application potential, which is the driving force and basis for the completion of this invention. Summary of the invention

[0004] The present invention provides an on-line in-situ detection device and method for heavy metals, which is an on-line in-situ detection device for heavy metal ions based on anodic stripping voltammetry, which solves the technical bottleneck that traditional electrochemical methods cannot monitor heavy metal ions in groundwater online, realizes the function of real-time on-line monitoring of heavy metal ions in groundwater, and ensures high sensitivity and high precision of heavy metal ion detection.

[0005] One of the technical solutions adopted by the present invention is:

[0006] Provided is an online in-situ heavy metal detection device, comprising a water sample detection chamber and a control end; a detection sensor and a water level detection probe are arranged in the water sample detection chamber, and the detection sensor and the water level detection probe communicate with the control end respectively; the detection sensor comprises a detection chamber shell and an electrode chamber A and an electrode chamber B arranged in the detection chamber shell, an auxiliary electrode is arranged in the electrode chamber A, and a reference electrode, a working electrode, a stirrer and a pH probe are arranged in the electrode chamber B; the electrode chamber A is an auxiliary area for accommodating an acid solution, and the electrode chamber B is a detection area for accommodating a CH3COO- solution; the electrode chamber A supplies H+ to the electrode chamber B under the control of the control end, so as to create an optimal buffer detection environment for the heavy metals in the electrode chamber B; under the control of the control end, the heavy metals in the water sample entering the water sample detection chamber enter the electrode chamber B to be enriched and dissolved, and the control end analyzes and detects the type and content of the heavy metals according to the intensity and position of the dissolution peak.

[0007] Furthermore, the auxiliary electrode in the electrode chamber A, the reference electrode, the working electrode, the stirrer and the pH probe in the electrode chamber B are electrically connected to the control end respectively. The control end collects the detection data after the heavy metal is dissolved in the electrode chamber B for subsequent analysis.

[0008] Furthermore, a proton exchange membrane is arranged in the detection chamber shell, which divides the space in the detection chamber shell into the electrode chamber A and the electrode chamber B; a cation exchange membrane is arranged on the side wall of the detection chamber shell on the side of the electrode chamber B away from the electrode chamber A.

[0009] Furthermore, a battery compartment is provided in the water sample detection compartment above the detection compartment shell, and the battery compartment is used to accommodate cables respectively connected to the auxiliary electrode, reference electrode, working electrode, stirrer, pH probe, and water level detection probe.

[0010] Furthermore, the water level detection probe is arranged in the water sample detection chamber outside the detection chamber shell.

[0011] Furthermore, the detection sensor is fixedly connected or detachably supported on the inner wall of the water sample detection chamber.

[0012] Furthermore, the detection sensor is supported by a support rod and arranged in the water level detection chamber. The support rod can be connected to the inner wall of the water level detection chamber by a detachable structure such as a snap connection.

[0013] Furthermore, the detection sensor is in a rectangular parallelepiped shape.

[0014] Furthermore, the control end includes an electrochemical workstation, a power supply, a display, and a GPS signal radar system.

[0015] Furthermore, a two-way valve is arranged at the water inlet at the bottom of the water sample detection chamber, and the two-way valve is opened or closed by the control end.

[0016] Furthermore, the above-mentioned heavy metal online in-situ detection device also includes a water sample extraction chamber, which is arranged above the water sample detection chamber, and the water sample extraction chamber and the water sample detection chamber are detachably sealed and assembled; a two-way valve is arranged at the water inlet at the bottom end of the water sample detection chamber, and the water sample extraction chamber and the two-way valve are both in communication with the control end, and the water sample extraction chamber extracts the water sample through the two-way valve into the water sample detection chamber under the control of the control end; a sediment particle filter is arranged at the bottom of the water sample detection chamber.

[0017] Furthermore, the water sample detection chamber is connected to the water sample extraction chamber. When the groundwater enters the water sample detection chamber through the two-way valve, it passes through the sediment particle filter before entering the subsequent detection stage.

[0018] Furthermore, the water sample extraction chamber and the water sample detection chamber are connected by an embedded connecting knob.

[0019] Furthermore, the control end controls the water in and out of the water sample extraction chamber by controlling the air compressor connected thereto. The upper end of the water sample extraction chamber is connected to an integrated cable, which includes an external cable and an air pipe, both of which are connected to the control end, and the air pipe controls the air compressor through the control end, thereby performing the extraction work.

[0020] Furthermore, the water sample extraction chamber includes a water inlet chamber and an air chamber, an air bag is arranged in the air chamber, the lower end of the air bag is connected to the water inlet chamber, and a gas gallery is arranged on the side wall of the air chamber outside the air bag, and the gas gallery is connected to the aforementioned air pipe; the air holes evenly distributed on the side wall of the air chamber connect the gas gallery with the air chamber.

[0021] The second technical solution adopted by the present invention is:

[0022] A method for online in-situ detection of heavy metals is provided, and the detection steps include:

[0023] S1 sends corresponding pumping instructions through the control end according to the detection requirements, the water sample extraction chamber works, and the groundwater enters the water sample detection chamber through the two-way valve; when the water level detection probe detects that the water level reaches the predetermined standard, the control end controls the two-way valve to stop water inflow;

[0024] The S2 control terminal issues the first step of electrochemical detection - the constant current mode command, creating the best buffer environment for detection. At this time, the acid solution in the electrode chamber A of the detection sensor electrolyzes H + , under the action of current, H is transported to electrode chamber B + , and CH3COO in electrode chamber B - A buffer environment is formed, and the optimal pH detection state of the corresponding parameters corresponding to the different heavy metal ions preset by the control end is gradually reached; when the pH probe detects that the pH of the water sample in the electrode chamber B has reached the preset range, the first stage of work is completed;

[0025] The S3 control terminal issues the second part of the electrochemical detection instruction - the differential pulse anodic stripping voltammetric mode instruction. According to the corresponding enrichment voltage, enrichment time, starting voltage, terminal voltage and rest time for different heavy metal detections set in advance on the control terminal, after the instruction is issued, the first enrichment process will transport the heavy metal ions in the water sample surrounding the detection chamber shell to the electrode chamber B and enrich them on the surface of the working electrode. After reaching the preset enrichment time, the dissolution process begins, the heavy metal ions are released, and when the dissolution process ends, the detection data is received by the control terminal;

[0026] The electrochemical workstation set up at the S4 control end processes and analyzes the collected data, performs qualitative identification through peak position, and converts peak intensity into corresponding heavy metal content through quantitative algorithm, completing multi-channel parallel detection of the total amount and form of heavy metals in groundwater;

[0027] After the S5 test is completed, the control end issues a command to start the water sample extraction chamber to form a positive pressure environment in the water sample extraction chamber, and the water sample is smoothly discharged from the water sample detection chamber through the two-way valve.

[0028] Furthermore, in the first step of constant current mode instruction in S2, the scan rate is set to 0.5 V / s; in the second step of differential pulse anodic stripping voltammetry mode instruction in S3, the enrichment voltage, enrichment time, starting voltage, end voltage and standing time are pre-set accordingly based on the needs of different heavy metal ion detection.

[0029] Furthermore, this detection method can be used to detect heavy metal Cd in groundwater samples. 2+ , Pb 2+ , Cu 2+ Separate or simultaneous qualitative and quantitative detection.

[0030] Furthermore, this detection method can achieve high sensitivity and accuracy in the detection of heavy metal Cd in groundwater samples. 2+ , Pb 2+ Qualitative and quantitative testing.

[0031] Beneficial effects of the present invention:

[0032] 1. The heavy metal online in-situ detection device of the present invention realizes the function of real-time online monitoring of heavy metal ions in water bodies by designing a special electrolytic cell structure and combining the "diffusion film-ion compensation" principle to transform the components of the detection device. It has the advantages of high sensitivity and high precision, and solves the technical bottleneck that traditional electrochemical methods cannot monitor heavy metal ions in groundwater online.

[0033] 2. The device of the present invention can realize qualitative and quantitative detection of different heavy metal ions in the best buffer detection environment by two key electrochemical instructions according to the corresponding detection operation method. It truly overcomes the limitations of traditional electrochemical methods in complex water environments and has broad application prospects.

[0034] 3. The heavy metal online in-situ detection device of the present invention can not only meet the requirements of groundwater in-situ detection, but also be used for ordinary water quality and water sample detection due to its small size structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the structure of the detection device of the present invention;

[0036] Figure 2 Figure 1 A schematic diagram of a cross-sectional structure of the device;

[0037] Figure 3 for Figure 2 Schematic diagram of the structure of the middle part A (detection sensor);

[0038] Figure 4 for Figure 1 Schematic diagram of the overall external style;

[0039] Figure 5 for Figure 4 Top view;

[0040] Figure 6 The glassy carbon electrode of Example 2 of the present invention is 1-50 μg / L Cd 2+ , Pb 2+ and Cu 2+ Differential pulse anodic stripping voltammetry analysis response diagram; the inset is the linear relationship between the corresponding peak intensity and the heavy metal ion concentration; (a)-(c) correspond to Cd 2+ , Pb 2+ and Cu 2+ ;

[0041] Figure 7 The glassy carbon electrode of Example 3 of the present invention is used to measure Cd 2+ , Pb 2+ and Cu 2+ Cyclic experiment; (a) is the simultaneous determination of Cd by glassy carbon electrode 2+ , Pb 2+ and Cu 2+ For different anions CO3 2- , Cl - 、SO4 2- 、NO3 - The selective experimental results of (b) are the simultaneous determination of Cd by glassy carbon electrode. 2+, Pb 2+ and Cu 2+ For different cations Al 3+ , Ca 2+ 、Co 2+ , Fe 3+ , K + Mg 2+ , Mn 2+ 、Zn 2+ Selective experiment.

[0042] Among them, 1 water sample extraction chamber, 2 water sample detection chamber, 3 two-way valve, 4 connecting knob, 5 internal cable profile, 6 sediment particle filter, 7 water inlet chamber, 8 air chamber, 9 air bag, 10 air hole, 11 gas pipeline gallery, 12 integrated cable interface, 13 integrated cable, 14 external cable pipeline gallery, 15 air pipe, 16 water level detection probe, 17 control terminal, 18 battery compartment, 19 detection chamber shell, 20 proton exchange membrane, 21 cation exchange membrane, 22 auxiliary electrode, 23 reference electrode, 24 working electrode, 25 agitator, 26 pH probe, 27 electrode chamber A, 28 electrode chamber B. DETAILED DESCRIPTION

[0043] In order to clearly illustrate the technical features of the present invention, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0044] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0045] The embodiment of the present invention provides an apparatus and method for realizing online in-situ detection of heavy metals in groundwater. Through the in-situ electrochemical pH control technology of hydrogen permeable conductive film and series double-chamber electrolytic cell configuration, the electrode online detection microenvironment is stable and adjustable, and the detection sensitivity and accuracy are improved. According to the actual engineering adjustment of the environmental parameters in the device, the detection of heavy metals in water by the device is further studied, which is described in detail below.

[0046] Example 1

[0047] The heavy metal online in-situ detection device can be assembled and online detection of heavy metal ion content can be performed according to the following steps:

[0048] See also Figure 1The heavy metal online in-situ detection device comprises a water sample extraction chamber 1, a water sample detection chamber 2, a two-way valve 3, a connection knob 4 and a control terminal 17. The control terminal comprises an electrochemical workstation, a power supply, a display, a GPS signal radar system and an air compressor.

[0049] The water sample extraction chamber 1 and the water sample detection chamber 2 are connected to each other through a connecting knob 4. The two-way valve 3 is arranged at the water inlet at the bottom of the water sample detection chamber 2. An integrated cable interface 12 is arranged at the top of the water sample extraction chamber. The control terminal 17 is connected to the integrated cable interface 12 at the top of the water sample extraction chamber 1 via an integrated cable 13.

[0050] Specifically, the water sample extraction chamber 1 includes a water inlet chamber 7 and an air chamber 8, an air bag 9 is arranged in the air chamber, and a gas gallery 11 is provided on the side wall of the air chamber 8. The gas gallery 11 is connected with the air pipe 15 in the integrated cable 13, and the air holes 10 evenly distributed on the side wall of the air chamber connect the gas gallery 11 with the air chamber 8. The air bag 9 is wrapped in the air chamber 8, and the lower end of the air bag is connected with the water inlet chamber 7.

[0051] The integrated cable 13 contains an external cable corridor 14 and an air pipe 15, which are connected to a control terminal 17. The air pipe 15 controls the air compressor through the control terminal to perform corresponding work.

[0052] A detection sensor and a water level detection probe 16 are provided in the water sample detection chamber 2, and the detection sensor and the water level detection probe are respectively connected to the control terminal 17. The detection sensor includes a battery chamber 18, a detection chamber shell 19, and an electrode chamber A and an electrode chamber B provided in the detection chamber shell, and the electrode chamber A and the electrode chamber B are indicated by reference numerals 27 and 28, respectively.

[0053] See also Figure 2 , Figure 3 The detection chamber shell 19 of the detection sensor is divided into electrode chamber A and electrode chamber B by a proton exchange membrane 20, and a cation exchange membrane 21 is set on the side wall of the detection chamber shell on the right side of electrode chamber B. An auxiliary electrode 22 is set in electrode chamber A, and a reference electrode 23, a working electrode 24, a stirrer 25 and a pH probe 26 are set in electrode chamber B. Electrode chamber A contains 1M CH3COOH solution, and electrode chamber B contains 0.1M CH3COONa solution. The cation exchange membrane is in direct contact with the water sample entering the water sample detection chamber. Under the control of the control terminal, electrode chamber A supplies H+ to electrode chamber B in time to create the best buffer detection environment for heavy metals in electrode chamber B; under the control of the control terminal 17, heavy metals in the water sample entering the water sample detection chamber can freely enter electrode chamber B.

[0054] The battery compartment 18 is used to accommodate cables connected to the auxiliary electrode 22, the reference electrode 23, the working electrode 24, the agitator 25, the pH probe 26, and the water level detection probe 16. The water level detection probe is arranged in the water sample detection compartment 2 outside the detection compartment housing 19. The cable connected to the two-way valve is connected to the control terminal through the internal cable profile 5 arranged in the compartment wall of the water sample detection compartment and the integrated cable interface at the top of the water sample extraction compartment. A sediment particle filter 6 is arranged at the bottom of the water sample detection compartment to filter the sediment particles in the groundwater entering the water sample detection compartment.

[0055] The detection sensor is detachably supported on the inner wall of the water sample detection chamber 2. For example, it can be fixed to the inner wall of the water sample detection chamber by a connecting rod provided on the outer side of the top of the detection sensor. The fixing can adopt a snap-on fixing structure. Of course, other existing structures that are convenient for disassembly can also be adopted, which will not be described in detail here. In this way, the water sample detector is open all around, so that the water sample detection chamber is connected to the water inlet chamber of the water sample extraction chamber, and the work in the water sample extraction chamber 1 can be carried out smoothly.

[0056] Figure 4 , Figure 5 The external overall style of the heavy metal online in-situ detection device is respectively illustrated.

[0057] The method for using the above detection device specifically includes the following steps:

[0058] (a) After assembling the above structural components, place the device vertically into the water sample to be tested;

[0059] (b) A command is issued through the control terminal 17, and the water sample extraction chamber 1 begins to transport and discharge the water sample by controlling the gas under the action of the air compressor 16. When the water sample enters the water sample detection chamber 2 through the two-way valve 3, the water level detection probe 16 detects that the water level is less than half of the working electrode 24, and then sends a stop water inlet signal to the control terminal, and the control terminal outputs a command to close the two-way valve.

[0060] Then the detection phase officially begins. First, the first step of electrochemical detection (constant current mode) is issued through the control terminal to create the best buffer environment for detection. At this time, the acid solution in the electrode chamber A in the detection sensor will electrolyze H + , under the action of the current, H is transported to the electrode chamber B through the proton exchange membrane 20. + , and CH3COO in electrode chamber B - A buffer environment is formed so that the detection environment gradually reaches the optimal pH detection state (different heavy metal ions have different suitable detection solution pH values, and the corresponding parameters can be set in advance at the control terminal). When the pH probe 26 detects that the pH value of the water sample in the electrode chamber B has reached the preset range, the first stage of work is completed.

[0061] Subsequently, the control terminal issues the second step of electrochemical detection (differential pulse anodic stripping voltammetric mode) instructions, and pre-sets the optimal detection parameters in the control terminal (different heavy metal detections will correspond to corresponding enrichment voltages, enrichment times, starting voltages, terminal voltages, and standing times). When the command is issued, the first enrichment process will transport the heavy metal ions in the water sample surrounding the detection chamber shell 19 to the electrode chamber B under the action of the cation exchange membrane 21, and gradually enrich them on the surface of the working electrode 24 in the electrode chamber B as the enrichment time increases. When the preset enrichment time is reached, the dissolution process is started. At this time, the heavy metal ions originally enriched on the electrode surface will be released. When the dissolution process is completed, the detection data is transmitted to the control terminal. The electrochemical workstation of the control terminal processes and analyzes the collected data, performs qualitative identification through peak position, and converts peak intensity into content through quantitative algorithms, thereby realizing multi-channel parallel detection of the total amount and form of heavy metals in groundwater.

[0062] After the test is completed, the control end issues a command, the air compressor starts working, and the gas creates a positive pressure environment in the water sample extraction chamber, and the water sample is smoothly discharged from the test chamber through the two-way valve. This method can perform non-disturbance, rapid and continuous sampling, and realizes the in-situ online detection of heavy metals in groundwater.

[0063] Example 2

[0064] Based on the on-line in-situ detection device and method for heavy metals in groundwater of Example 1, the working electrode is a glassy carbon electrode, the reference electrode is an Ag / AgCl electrode, and the auxiliary electrode is a platinum electrode.

[0065] The detection device was immersed in Cd containing 1-50 μg / L concentration range. 2+ , Pb 2+ and Cu 2+ In-situ online detection is carried out on the heavy metal water samples to be tested.

[0066] To detect Cd in the above 1-50μg / L concentration range 2+ For example, in the first step of the in-situ online detection, the control end scanning speed is set to 0.5V / s. At this time, the acid solution in the electrode chamber A will electrolyze H + , under the action of current, H is transported to electrode chamber B through the proton exchange membrane + , and CH3COO in electrode chamber B - Form a buffer environment so that the detection environment gradually reaches the level used to detect Cd 2+ The optimal pH (4.5) detection state; the second step instruction, the control end enrichment voltage, enrichment time, starting voltage, end voltage and static time are set to -1.3V, 180s, -1.3V, 0V, 10s, respectively, Cd 2+In this enrichment process, the cation exchange membrane enters the electrode chamber B through the right side of the electrode chamber B and is enriched on the surface of the working electrode. After the corresponding enrichment time, the dissolution process is started to make Cd 2+ When the dissolution process is completed, the detection data is transmitted to the control terminal, and the electrochemical workstation of the control terminal processes and analyzes the collected data.

[0067] Results Figure 6 .in, Figure 6 (a) is Cd 2+ Differential pulse anodic stripping voltammetry analysis response diagram shows that the dissolution peak intensity increases linearly with the increase of heavy metal ion concentration in the solution, and the position of the dissolution peak moves slightly toward the positive voltage direction with the increase of heavy metal ion concentration in the solution; Figure 6 (b) is Pb 2+ Differential pulse anodic stripping voltammetry analysis response diagram shows that the dissolution peak intensity increases linearly with the increase of heavy metal ion concentration in the solution, and the position of the dissolution peak moves slightly toward the positive voltage direction with the increase of heavy metal ion concentration in the solution; Figure 6 (c) is Cu 2+ The response diagram of differential pulse anodic stripping voltammetry analysis shows that the intensity of the dissolution peak increases linearly with the increase of the heavy metal ion concentration in the solution, and the position of the dissolution peak does not move significantly toward the positive voltage direction with the increase of the heavy metal ion concentration in the solution.

[0068] Table 1 Glassy carbon electrode for Cd 2+ , Pb 2+ and Cu 2+ The lowest detection limit of differential pulse anodic stripping voltammetry response

[0069]

[0070] Table 1 shows the glassy carbon electrode of this embodiment for Cd 2+ , Pb 2+ and Cu 2+ The lowest detection limit of the response was obtained by differential pulse anodic stripping voltammetry.

[0071] The above results are obtained by calculating Cd using formula (1) 2+ , Pb 2+ and Cu 2+ The minimum detection limits were 1.14μg / L, 0.65μg / L, and 0.22μg / L, respectively.

[0072] y=ax+b (1)

[0073] LOD=3σ / K

[0074] Where: a---response peak current value, μA;

[0075] x---heavy metal ion concentration, μg / L;

[0076] a---slope of linear fitting equation;

[0077] b---intercept of linear fitting equation;

[0078] LOD---limit of detection;

[0079] σ---relative standard deviation;

[0080] K---the slope of the linear equation.

[0081] Example 3

[0082] Based on the on-line in-situ detection device and method for heavy metals in groundwater of Example 1, the working electrode is a glassy carbon electrode, the reference electrode is an Ag / AgCl electrode, and the auxiliary electrode is a platinum electrode.

[0083] Prepare a water sample containing a fixed type of heavy metals to be tested (containing 20μg / L concentration of Pb 2+ , 20μg / L Cd 2+ and 20 μg / L Cu 2+ ), adding different anions (CO3 2- , Cl - 、SO4 2- 、NO3 - ) and cation (Al 3+ , Ca 2+ , CO 2+ , Fe 3+ , K + Mg 2+ , Mn 2+ 、Zn 2+ ) for in-situ online interference detection, and other detection parameters are quantitative, specifically set as follows:

[0084] The control end scan rate was set to 0.5 V / s, the detection environment pH = 4.5, the control end enrichment voltage -1.2 V, the enrichment time 180 s, the starting voltage -1.3 V, the terminal voltage 0.5 V and the standing time 10 s.

[0085] Results Figure 7 , Figure 7 (a) is Pb 2+ 、Cd 2+ and Cu 2+ The results of the interference test of the dissolution peak intensity for different anions showed that they were all within the acceptable range. Therefore, the anions had a significant influence on the Pb 2+ 、Cd 2+ and Cu2+ The influence of can be appropriately ignored; Figure 7 (b) is Pb 2+ 、Cd 2+ and Cu 2+ The dissolution peak intensity of different cations was tested for interference, and the results were analyzed. 2+ and Pb 2+ The interference from cations is small, but Cu 2+ The interference of cations is more obvious. The reason for this situation may be that potential overlap leads to signal confusion, making it difficult to accurately distinguish the response of copper ions, or competitive reduction or oxidation leads to Cu 2+ Cannot participate in the reaction preferentially, thus reducing the signal intensity or even completely covering up the Cu 2+ response, these factors will lead to Cu 2+ The detection effect is affected.

[0086] Tables 2 and 3 below show the glassy carbon electrode's response to anions (CO3 2- , Cl - 、SO4 2- 、NO3 - ) and cations (Al 3+ , Ca 2+ , CO 2+ , Fe 3+ , K + Mg 2+ , Mn 2+ 、Zn 2+ ) after the peak current comparison. The peak current data comparison can show that the detection of Cu in groundwater 2+ Technical improvements are needed, but Pb 2+ and Cd 2+ There is no obvious effect under the interference of anions or cations, and effective analysis results can be obtained.

[0087] Table 2 Glassy carbon electrode for Cd 2+ , Pb 2+ and Cu 2+ Add 30 times the concentration of CO3 2- , Cl - 、SO4 2- 、NO3 - Peak current comparison after

[0088]

[0089] Table 3 Glassy carbon electrode for Cd 2+ , Pb 2+ and Cu 2+ Add 30 times the concentration of Al 3+ , Ca2+ 、Co 2+ , Fe 3+ , K + Mg 2+ , Mn 2 + 、Zn 2+ Peak current comparison after

[0090]

[0091] The above specific implementation manner cannot be used as a limitation on the protection scope of the present invention. For those skilled in the art, any substitution, improvement or change made to the implementation manner of the present invention falls within the protection scope of the present invention.

[0092] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A heavy metal online in-situ detection device, characterized in that: It includes a water sample detection chamber and a control end; a detection sensor and a water level detection probe are arranged in the water sample detection chamber, and the detection sensor and the water level detection probe communicate with the control end respectively; The detection sensor includes a detection chamber shell and electrode chamber A and electrode chamber B arranged in the detection chamber shell. An auxiliary electrode is arranged in electrode chamber A, and a reference electrode, a working electrode, a stirrer and a pH probe are arranged in electrode chamber B. Electrode chamber A is an auxiliary area for accommodating acid solution, and electrode chamber B is a detection area for accommodating CH3COO- solution. Under the control of the control end, electrode chamber A supplies H+ to electrode chamber B to create an optimal buffer detection environment for heavy metals in electrode chamber B. Under the control of the control end, heavy metals in the water sample entering the water sample detection chamber enter the electrode chamber B to achieve enrichment and dissolution.

2. The heavy metal online in-situ detection device according to claim 1, characterized in that: A proton exchange membrane is arranged in the detection chamber shell, and the proton exchange membrane divides the space in the detection chamber shell into the electrode chamber A and the electrode chamber B; a cation exchange membrane is arranged on the side wall of the detection chamber shell on the side of the electrode chamber B away from the electrode chamber A.

3. The heavy metal online in-situ detection device according to claim 1, characterized in that: A battery compartment is arranged in the water sample detection compartment above the detection compartment shell, and the battery compartment is used to accommodate cables respectively connected to the auxiliary electrode, the reference electrode, the working electrode, the stirrer, the pH probe, and the water level detection probe.

4. The heavy metal online in-situ detection device according to claim 1, characterized in that: The water level detection probe is arranged in the water sample detection chamber outside the detection chamber shell.

5. The heavy metal online in-situ detection device according to claim 1, characterized in that: The detection sensor is fixedly connected or detachably supported on the inner wall of the water sample detection chamber.

6. The heavy metal online in-situ detection device according to claim 1, characterized in that: The control end includes an electrochemical workstation, a power supply, a display, and a GPS signal radar system.

7. The heavy metal online in-situ detection device according to claim 1, characterized in that: A two-way valve is arranged at the bottom of the water sample detection chamber, and the opening and closing of the two-way valve is controlled by the control end.

8. The heavy metal online in-situ detection device according to any one of claims 1 to 6, characterized in that: It also includes a water sample extraction chamber and a two-way valve. The water sample extraction chamber is arranged above the water sample detection chamber. The water sample extraction chamber and the water sample detection chamber are detachably sealed and assembled. The two-way valve is arranged at the water inlet at the bottom of the water sample detection chamber. The water sample extraction chamber and the two-way valve are both communicated with the control end. Under the control of the control end, the water sample extraction chamber extracts the water sample through the two-way valve into the water sample detection chamber; a sediment particle filter is arranged at the bottom of the water sample detection chamber.

9. A method for online in-situ detection of heavy metals, characterized in that: The heavy metal online in-situ detection device according to any one of claims 1 to 7 is used for detection, and the detection steps include: When the water level in the water sample detection chamber detected by the water level detection probe reaches the preset requirement, the control end issues the first step of electrochemical detection instruction - constant current mode instruction to create the best buffer environment for detection; at this time, the acid solution in the electrode chamber A of the detection sensor electrolyzes H + , under the action of current, H is transported to electrode chamber B + , and CH3COO in electrode chamber B - A buffer environment is formed, and the optimal pH detection state of the corresponding parameters corresponding to the different heavy metal ions preset by the control end is gradually reached; when the pH probe detects that the pH of the water sample in the electrode chamber B has reached the preset range, the first stage of work is completed; The S2 control terminal issues the second electrochemical detection instruction - the differential pulse anodic stripping voltammetric mode instruction. According to the corresponding enrichment voltage, enrichment time, starting voltage, terminal voltage and rest time for different heavy metal detections set in advance on the control terminal, after the instruction is issued, the first enrichment process will transport the heavy metal ions in the water sample surrounding the detection chamber shell to the electrode chamber B and enrich them on the surface of the working electrode. After reaching the preset enrichment time, the dissolution process begins, the heavy metal ions are released, and when the dissolution process ends, the detection data is received by the control terminal; The electrochemical workstation set up at the S3 control end processes and analyzes the collected data, performs qualitative identification through peak position, and converts peak intensity into corresponding heavy metal content through quantitative algorithms, completing multi-channel parallel detection of the total amount and form of heavy metals in groundwater.

10. A method for online in-situ detection of heavy metals, characterized in that: The heavy metal online in-situ detection device according to claim 8 is used for detection, and the detection steps include: S1 sends corresponding pumping instructions through the control end according to the detection requirements, the water sample extraction chamber works, and the groundwater enters the water sample detection chamber through the two-way valve; when the water level detection probe detects that the water level reaches the predetermined standard, the control end controls the two-way valve to stop water inflow; The S2 control terminal issues the first step of electrochemical detection - the constant current mode command, creating the best buffer environment for detection. At this time, the acid solution in the electrode chamber A of the detection sensor electrolyzes H + , under the action of current, H is transported to electrode chamber B + , and CH3COO in electrode chamber B - A buffer environment is formed, and the optimal pH detection state of the corresponding parameters corresponding to the different heavy metal ions preset by the control end is gradually reached; when the pH probe detects that the pH of the water sample in the electrode chamber B has reached the preset range, the first stage of work is completed; The S3 control terminal issues the second part of the electrochemical detection instruction - the differential pulse anodic stripping voltammetric mode instruction. According to the corresponding enrichment voltage, enrichment time, starting voltage, terminal voltage and rest time for different heavy metal detections set in advance on the control terminal, after the instruction is issued, the first enrichment process will transport the heavy metal ions in the water sample surrounding the detection chamber shell to the electrode chamber B and enrich them on the surface of the working electrode. After reaching the preset enrichment time, the dissolution process begins, the heavy metal ions are released, and when the dissolution process ends, the detection data is received by the control terminal; The electrochemical workstation set up at the S4 control end processes and analyzes the collected data, performs qualitative identification through peak position, and converts peak intensity into corresponding heavy metal content through quantitative algorithm, completing multi-channel parallel detection of the total amount and form of heavy metals in groundwater; After the S5 test is completed, the control end issues a command to start the water sample extraction chamber to form a positive pressure environment in the water sample extraction chamber, and the water sample is smoothly discharged from the water sample detection chamber through the two-way valve.

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