Electrochemical detection method for heavy metal ions

Abstract

The invention relates to the technical field of heavy metal ion detection, and particularly discloses a heavy metal ion electrochemical detection method which comprises the following steps: A1, selecting electrochemical detection equipment, A2, selecting a solution to be detected, and temporarily storing the solution to be detected, an electrode coating solution and a digestion solution in the electrochemical detection equipment for later use respectively, the method comprises the following steps: A1, preparing an electrode coating solution, A2, preparing a digestion solution, A3, extracting the electrode coating solution into electrochemical detection equipment, A4, extracting the solution to be detected and the digestion solution into an electrolytic tank of a working station of the electrochemical detection equipment to enrich heavy metal ions in the solution to be detected, and A5, measuring by the working station through DPV (differential pulse voltammetry), and determining the heavy metal content through DPV peak searching and base line. The problem that in the traditional electrochemical detection process, only a single heavy metal element can be detected generally, and a sample with complex components is difficult to measure is solved.

Description

Technical Field

[0001] The present application relates to the technical field of heavy metal ion detection, and specifically discloses a heavy metal ion electrochemical detection method. Background Art

[0002] Metals can be divided into heavy metals and light metals according to their density. 3 Metals that are discharged into the environment are called heavy metals, such as lead, mercury, thallium, etc. Heavy metals are harmful to human health and the environment. When heavy metals are discharged into the environment, serious environmental problems will occur. Therefore, the detection and removal of heavy metal ions in the environment, especially in water, is of great significance.

[0003] Traditional heavy metal detection methods include spectrophotometry, atomic absorption spectroscopy, chemiluminescence analysis, ion chromatography and its combined techniques, high performance liquid chromatography and its combined techniques, electrochemical analysis, etc.

[0004] Now let's focus on electrochemical analysis. Compared with other methods, the color and turbidity of the sample have almost no effect on the electrochemical analysis method, and no complicated pre-treatment steps are required. It specifically includes potentiometric analysis, conductivity analysis, coulometric analysis and voltammetric analysis, among which ion selective electrode method and chronoamperometry are commonly used to detect heavy metals. For the ion selective electrode method, the solution to be tested is usually placed in an electrochemical analysis instrument, and the heavy metal ion detection is achieved through the electrochemical analysis instrument.

[0005] When the solution to be tested is loaded, a mercury film solution, a masking agent, and ultrapure water are also loaded. The extraction of different solutions is achieved through a shunt switch controlled by a lower computer in the electrochemical analyzer. The solution is extracted quantitatively by a piston pump in conjunction with a liquid level sensor. A mercury film is plated on the working electrode with a mercury film solution in conjunction with a stirrer. The workstation then achieves ion enrichment in the solution to be tested and measures it through differential pulse voltammetry: DPV. The heavy metal content is determined by DPV peak finding and baseline.

[0006] However, in the existing electrochemical detection process of heavy metal ions, the solution loaded only includes the solution to be tested, the mercury film solution, the masking agent and ultrapure water. During the electrochemical detection process, usually only a single heavy metal element can be detected, and it is difficult to measure samples with complex components.

[0007] Therefore, in view of this, the inventor provides a method for electrochemical detection of heavy metal ions to solve the above problems. Summary of the invention

[0008] The purpose of the present invention is to solve the problem that in the traditional electrochemical detection process, usually only a single heavy metal element can be detected, but it is difficult to detect samples with complex components.

[0009] In order to achieve the above object, the basic scheme of the present invention provides a method for electrochemical detection of heavy metal ions, comprising the following steps:

[0010] Step A1: selecting an electrochemical detection device, wherein the electrochemical detection device includes a working electrode, a counter electrode and a reference electrode;

[0011] Step A2: Select a solution to be tested, and temporarily store the solution to be tested, the electrode plating solution and the digestion solution in an electrochemical detection device for later use;

[0012] Step A3: extracting the electrode coating solution into the electrolytic cell of the workstation of the electrochemical detection equipment, and coating the working electrode;

[0013] Step A4: extracting the test solution and the digestion solution into the electrolytic cell of the workstation of the electrochemical detection equipment, and enriching the heavy metal ions in the test solution by the redox reaction of the heavy metal ions in the test solution in the electrolytic cell;

[0014] Step A5: The workstation performs measurement by differential pulse voltammetry: DPV, and determines the heavy metal content by DPV peak search and baseline.

[0015] Furthermore, in step A2, the standard solution is temporarily stored in the electrochemical detection device for later use. In step A4, the extracted solution includes the standard solution.

[0016] Furthermore, in step A2, the ultrapure water is temporarily stored in the electrochemical detection device for use. During the electrochemical detection process, the following steps are also included:

[0017] Step A6: Drain the solution in the workstation of the electrochemical detection equipment, and draw ultrapure water to rinse the electrolytic cell in the workstation.

[0018] Furthermore, in step A2, the masking agent is temporarily stored in the electrochemical detection device for later use, and in step A4, the extracted solution includes the masking agent.

[0019] Furthermore, the digestion solution is a nitric acid solution.

[0020] Furthermore, the working electrode is an Ag / Bi electrode.

[0021] Furthermore, the workstation is also equipped with cyclic voltammetry: CV and electrochemical impedance spectroscopy: EIS to calibrate the unmodified working electrode and reference electrode respectively.

[0022] The principle and effect of this scheme are:

[0023] 1. Compared with the prior art, the present invention adds a digestion solution to the solution to be tested, so that during the redox reaction, it can cope with water samples under complex working conditions, solving the problem that in the traditional electrochemical detection process, usually only a single heavy metal element can be detected, and it is difficult to measure samples with complex components.

[0024] 2. Compared with the prior art, the present invention further improves the working electrode to an Ag / Bi electrode, which reduces costs and increases efficiency and is non-toxic and harmless.

[0025] 3. Compared with the prior art, the present invention increases the standard solution and improves the confidence of sensitivity. At the same time, the workstation is also equipped with two functions: cyclic voltammetry and AC impedance to calibrate the unmodified working electrode and reference electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram showing the components of an electrochemical detection device for an electrochemical detection method for heavy metal ions proposed in an embodiment of the present application;

[0028] Figure 2 A flow chart of a heavy metal ion electrochemical detection method proposed in an embodiment of the present application is shown;

[0029] Figure 3 A schematic diagram of the structure of an electrochemical detection device proposed in an embodiment of the present application is shown;

[0030] Figure 4 A partial structural schematic diagram of an electrochemical detection device proposed in an embodiment of the present application is shown;

[0031] Figure 5 The working principle diagram of the gas circuit and liquid circuit of the electrochemical detection device proposed in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0032] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0033] The figure marks in the drawings of the specification include: electrolytic cell 1, one-way valve 2, corrosion-resistant valve 3, ordinary valve 4, quantitative tank 5, first liquid inlet 6, second liquid inlet 7, rotating motor 8, reference electrode 9, counter electrode 10, working electrode 11, liquid level sensor 12, first connecting port 13, second connecting port 14, liquid outlet 15.

[0034] A method for electrochemical detection of heavy metal ions, for example Figure 1 and Figure 2 As shown:

[0035] The steps include:

[0036] Step A1: Select an electrochemical detection device, which includes a working electrode 11 , a counter electrode 10 and a reference electrode 9 .

[0037] Specifically, the electrochemical detection device includes a main control unit, a display screen electrically connected to the main control unit, and a lower computer function control terminal electrically connected to the main control unit. The main control inputs control instructions to the lower computer function control terminal, and the feedback is displayed on the display screen. The lower computer function control terminal is connected to a shunt switch, a liquid level sensor 12, a workstation, an agitator, a piston pump, a valve, and a low-temperature heater. An electrolytic cell 1 is provided in the workstation and is equipped with a counter electrode 10, a reference electrode 9, and a working electrode 11, as well as a waste liquid cylinder connected to the electrolytic cell 1. The electrolytic cell 1 is connected to a plurality of quantitative tanks 5 through a pipeline.

[0038] In this embodiment, if Figure 3 and Figure 4 As shown, the bottom of the electrolytic cell 1 is connected to the waste liquid cylinder through a one-way valve 2, and the first liquid inlet 6 and the second liquid inlet 7 are respectively provided on both sides of the electrolytic cell 1. The second liquid inlet 7 is connected to the piston pump, and the first liquid inlet 6 is connected to a plurality of quantitative tanks 5 through a pipeline, and the quantitative tanks 5 are in turn connected to the pipeline and connected to the first liquid inlet 6 through a corrosion-resistant valve 3.

[0039] The counter electrode 10 , the reference electrode 9 and the working electrode 11 are mounted on a turntable. The reference electrode 9 and the counter electrode 10 are located on both sides of the working electrode 11 , respectively. The turntable is coaxially fixed and connected to the output shaft of a rotating motor 8 .

[0040] like Figure 3 As shown, there are eight quantitative grooves 5, which are P1, P2, P3, P4, P5, P6, P7 and P8 from left to right. A common valve 4 is installed between the bottom of P1 to P4 and the pipeline, and a corrosion-resistant valve 3 is installed between the bottom of P5 to P8 and the pipeline. In this embodiment, the installed corrosion-resistant valves 3 are all nitric acid-resistant corrosion-resistant valves 3.

[0041] like Figure 4As shown, the liquid level sensor 12 is installed and corresponds to a section of the quantitative tank 5 near the top. The quantitative tank 5 has a first connecting port 13 at the top and a second connecting port 14 at the bottom. The first connecting port 13 is used to draw air into the quantitative tank 5, and the second connecting port 14 is used to supply liquid into the quantitative tank 5. The quantitative tank 5 also has a liquid outlet 15 at the bottom.

[0042] Step A2: Select the solution to be tested, and temporarily store the solution to be tested, the electrode plating solution, the masking agent and the digestion solution in the quantitative tank 5 of the electrochemical detection device for later use.

[0043] Specifically, it also includes standard solution and ultrapure water. The digestion instrument is a nitric acid solution.

[0044] In this embodiment, the quantitative tank 5P1 is loaded with ultrapure water, the quantitative tank 5P2 is loaded with electrode plating solution, the quantitative tank 5P3 is loaded with masking agent, the quantitative tank 5P4 is an expansion tank, the quantitative tank 5P5 is an expansion tank, the quantitative tank 5P6 is loaded with standard solution, the quantitative tank 5P7 is loaded with test solution, and the quantitative tank 5P8 is loaded with digestion solution.

[0045] Step A3: extracting the electrode coating solution into the electrolytic cell 1 of the workstation of the electrochemical detection equipment, and coating the working electrode 11 .

[0046] Specifically, the shunt switch is controlled by the lower computer function control end in combination with the liquid level sensor 12 and the piston pump to achieve quantitative extraction of the electrode 10 coating solution. In the present embodiment, the electrode coating solution is a Bi solution, and after the Bi solution enters the electrolytic cell 1, the lower computer function control end drives the agitator to coat the working electrode 11. In the present embodiment, the working electrode 11 is an Ag / Bi electrode.

[0047] Step A4: extract the test solution, masking agent, nitric acid solution and standard solution into the electrolytic cell 1 of the workstation of the electrochemical detection equipment, and the heavy metal ions in the test solution undergo redox reaction in the electrolytic cell 1 to enrich the heavy metal ions in the test solution.

[0048] The solution to be tested, the masking agent, the nitric acid solution and the standard solution are quantitatively extracted by a piston pump, and a redox reaction occurs in the electrolytic cell 1 .

[0049] Step A5: The workstation performs measurement by differential pulse voltammetry: DPV, and determines the heavy metal content by DPV peak search and baseline.

[0050] Step A6: drain the solution in the workstation of the electrochemical detection equipment, and extract ultrapure water to rinse the electrolytic cell 1 in the workstation.

[0051] like Figure 5 The working principle diagram of the gas circuit and liquid circuit shown in the figure includes the following three processes:

[0052] Liquid supply process:

[0053] The valve between the corresponding liquid tank and the quantitative tank 5 is opened, and the pump draws air to suck the liquid into the quantitative tank 5. A liquid level sensor is also installed on the quantitative tank 5. When the liquid level sensor detects the liquid level, the valve between the corresponding liquid tank and the quantitative tank 5 is closed, and the pump is turned off.

[0054] The valve between the quantitative tank 5 and the electrolytic cell 1 and the electronically controlled pressure relief valve B are opened, and the pump delivers gas to push the liquid into the electrolytic cell 1.

[0055] The electronically controlled pressure relief valve A is opened, the pump is pumped, the electronically controlled pressure relief valve A is closed, the pump is supplied with gas, and the residual liquid is pushed into the electrolytic cell 1.

[0056] Drainage process:

[0057] After the test is completed, the electronically controlled pressure relief valve A is opened, the pump is pumped, and the electronically controlled pressure relief valve A is closed.

[0058] The electronically controlled valve A is opened, the corrosion-resistant valve 3A is opened, and the pump delivers gas to push all the liquid in the electrolytic cell 1 into the waste liquid tank.

[0059] Automatic cleaning process:

[0060] Replace all liquid tanks with new ultrapure water tanks. After three cycles of liquid supply and discharge, all valves are opened, the heater is turned on, and the pump continues to suck and deliver air to dry the residual water in the gas and liquid lines. After this process, all valves are closed.

[0061] The present invention adds a digestion solution to the solution to be tested, so that during the redox reaction, it can cope with water samples under complex working conditions, solving the problem that in the traditional electrochemical detection process, usually only a single heavy metal element can be detected, while it is difficult to measure samples with complex components.

[0062] The present invention also improves the working electrode 11 to be an Ag / Bi electrode, which reduces costs and increases efficiency and is non-toxic and harmless.

[0063] The present invention increases the standard solution to improve the confidence of sensitivity. At the same time, the workstation is also equipped with two functions of cyclic voltammetry and AC impedance to calibrate the unmodified working electrode 11 and the reference electrode 9.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for electrochemical detection of heavy metal ions, characterized in that: The steps include: Step A1: selecting an electrochemical detection device, wherein the electrochemical detection device includes a working electrode, a counter electrode and a reference electrode; Step A2: Select the solution to be tested, and temporarily store the solution to be tested and the electrode plating solution digestion solution in an electrochemical detection device for later use; Step A3: extracting the electrode coating solution into the electrolytic cell of the workstation of the electrochemical detection equipment, and coating the working electrode; Step A4: extracting the test solution and the digestion solution into the electrolytic cell of the workstation of the electrochemical detection equipment, and enriching the heavy metal ions in the test solution by the redox reaction of the heavy metal ions in the test solution in the electrolytic cell; Step A5: The workstation performs measurement by differential pulse voltammetry: DPV, and determines the heavy metal content by DPV peak search and baseline.

2. A heavy metal ion electrochemical detection method according to claim 1, characterized in that: In step A2, the standard solution is temporarily stored in the electrochemical detection device for later use. In step A4, the extracted solution includes the standard solution.

3. A heavy metal ion electrochemical detection method according to claim 2, characterized in that: In step A2, the ultrapure water is temporarily stored in the electrochemical detection device for use. During the electrochemical detection process, the following steps are also included: Step A6: Drain the solution in the workstation of the electrochemical detection equipment, and draw ultrapure water to rinse the electrolytic cell in the workstation.

4. The method for electrochemical detection of heavy metal ions according to claim 1, characterized in that: In step A2, the masking agent is temporarily stored in the electrochemical detection device for later use. In step A4, the extracted solution includes the masking agent.

5. The method for electrochemical detection of heavy metal ions according to claim 1, characterized in that: The digestion solution is a nitric acid solution.

6. The method for electrochemical detection of heavy metal ions according to claim 1, characterized in that: The working electrode is an Ag / Bi electrode.

7. The method for electrochemical detection of heavy metal ions according to claim 1, characterized in that: The workstation is also equipped with cyclic voltammetry: CV and electrochemical impedance spectroscopy: EIS to calibrate the unmodified working electrode and reference electrode respectively.

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