Electrochemical device for heavy metal ion detection

Abstract

The utility model discloses an electrochemical device for heavy metal ion detection. The electrochemical device comprises a shell, a miniature electrochemical workstation, a liquid feeding device and an electrochemical sensor, the shell is provided with a detection chamber, a mounting cavity, a liquid inlet and a material opening; the liquid feeding device is fixedly mounted in the mounting cavity, the liquid inlet end of the liquid feeding device is communicated with the liquid inlet, and the liquid outlet end of the liquid feeding device is communicated with the detection chamber; the micro electrochemical workstation is arranged on the shell and is connected with the electrochemical sensor; the electrochemical sensor comprises a working electrode, a reference electrode and a counter electrode, and the working electrode, the reference electrode and the counter electrode are arranged in the detection chamber; the material opening is communicated with the detection chamber and has an opening state and a closing state. According to the scheme, the problems that the process is complicated, time consumption is long, rapid detection is not facilitated, sampling and separation are not portable, and operation is not beneficial to popularization when electrochemical analysis and detection are carried out based on an electrochemical workstation at present can be solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to electrochemistry detection technical field especially relates to a kind of electrochemical device for heavy metal ion detection. BACKGROUND

[0002] There are many harmful heavy metals in industrial wastewater, mainly including pollutants such as mercury, cadmium, chromium and lead with high biological toxicity; these heavy metals can enter the human body through the gastrointestinal tract, especially lead can be directly absorbed through the skin, and heavy metals can damage and affect cell function after entering the human body, thereby interfering with the central nervous system, causing mental disorders, destroying plasma material balance, and possibly damaging important organs such as the lungs, liver and kidneys, aggravating the underlying disease condition, and cannot be degraded in the body.

[0003] Currently, the traditional detection methods for lead ions include atomic absorption spectrometry, inductively coupled plasma mass spectrometry, X-ray fluorescence spectrometry, etc. However, these methods are expensive, complex to operate, time-consuming, and cannot be monitored online. Therefore, developing a rapid, accurate, sensitive, and simple method for detecting low-concentration lead ions is an important research topic in recent years.

[0004] Compared with the above-mentioned traditional detection methods, electrochemical analysis has the advantages of simple equipment, easy automation, fast response speed, low cost, good stability, strong selectivity, high sensitivity, etc. Therefore, electrochemical analysis has been widely used in heavy metal ion analysis.

[0005] However, the existing electrochemical detection based on electrochemical workstations requires sampling, separation, assembly of ordinary three-electrode systems, etc. during testing, which is complex, time-consuming, not conducive to on-site rapid detection, and also has the problems of inconvenient on-site sampling and separation, and operation cannot be popularized, etc., thereby limiting its application in environmental pollution monitoring and food safety supervision. UTILITY MODEL CONTENT

[0006] The utility model discloses an electrochemical device for heavy metal ion detection to solve the problems of complex process, long time-consuming, inconvenient sampling and separation, and operation not conducive to popularization during electrochemical analysis and detection based on the electrochemical workstation.

[0007] To solve the above problems, the utility model adopts the following technical solutions:

[0008] An electrochemical device comprises a shell, a micro electrochemical workstation, a liquid feeding device and an electrochemical sensor; the shell is provided with a detection chamber, a mounting cavity, a liquid inlet and a material port; the liquid feeding device is fixedly installed in the mounting cavity, and the liquid inlet end of the liquid feeding device is communicated with the liquid inlet, and the liquid outlet end of the liquid feeding device is communicated with the detection chamber; the micro electrochemical workstation is arranged in the shell and connected with the electrochemical sensor; the electrochemical sensor comprises a working electrode, a reference electrode and a counter electrode, and the working electrode, the reference electrode and the counter electrode are arranged in the detection chamber; the material port is communicated with the detection chamber, and the material port has an open state and a closed state; the position of the liquid inlet is provided with a filter structure.

[0009] Optionally, CoFe2O4@ZIF-67 magnetic composite material or CoFe2O4@ZIF-67 / Nafion magnetic composite material is added in the detection chamber for lead ion detection; the working electrode is a magnetic electrode.

[0010] Optionally, the working electrode is an electrode with a substrate reaction end surface modified with CoFe2O4@ZIF-67 or CoFe2O4@ZIF-67 / Nafion for lead ion detection.

[0011] Optionally, the working electrode is a CoFe2O4@ZIF-67 / GCE electrode or a CoFe2O4@ZIF-67 / Nafion / GCE electrode; wherein the GCE as a substrate is a magnetic glassy carbon electrode.

[0012] Optionally, the reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum wire electrode.

[0013] Optionally, the liquid feeding device is a micro peristaltic pump.

[0014] Optionally, the liquid outlet end of the micro peristaltic pump is provided with a one-way valve.

[0015] Optionally, the part of the shell at the liquid inlet is in a tapered structure with a narrow front and a wide back.

[0016] The technical scheme adopted by the utility model can achieve the following beneficial effects:

[0017] The utility model discloses an electrochemical device for heavy metal ion detection adopts integrated design to make the electrochemical device has small, convenient to carry and simple operation and so on, wherein, through liquid feeding device can be measured liquid is automatically sent into detection chamber, and through the three electrode system formed by the electrochemical sensor in detection chamber cooperates micro electrochemical workstation and realizes qualitative quantitative detection analysis of heavy metal ion fast, and, through the material mouth can conveniently discharge and release the adsorbed measured liquid from the detection chamber in the detection process, also can conveniently add buffer solution etc. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings described herein are used to provide further understanding of the utility model, and constitute a part of the utility model, and the illustrative embodiment and the explanation thereof of the utility model are used to explain the utility model, and do not constitute undue limitation to the utility model.

[0019] Figure 1 It is the microcosmic surface appearance diagram of the magnetic composite material disclosed by the utility model;

[0020] Figure 2 It is the CV diagram of different modified electrodes;

[0021] Figure 3 It is the DPV curve of different modified electrodes;

[0022] Figure 4 It is the test result of stability (a) and reproducibility (b) of the electrochemical sensor disclosed by the utility model;

[0023] Figure 5 It is the anti-interference performance test structure of the electrochemical sensor disclosed by the utility model;

[0024] Figure 6 It is the structure schematic view of the electrochemical device disclosed by the utility model;

[0025] Figure 7 It is the detection result and linear equation of experimental sample;

[0026] EXPLANATION OF DRAWINGS:

[0027] 100 - shell, 101 - liquid inlet, 102 - detection chamber, 110 - filter structure, 120 - micro peristaltic pump, 121 - check valve, 130 - working electrode, 140 - reference electrode, 150 - counter electrode, 160 - micro electrochemical workstation. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model technical scheme will be described clearly and completely in combination with specific embodiments of the utility model and corresponding drawings below. Obviously, the described embodiments are only a part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0029] The technical scheme disclosed in each embodiment of the utility model will be described in detail below in combination with the drawings.

[0030] Embodiment 1

[0031] Preparation and characterization of magnetic composite CoFe2O4@ZIF-67

[0032] 0.2g of CoFe2O4 and 7g of dimethyl imidazole are dispersed in 50mL of methanol solution to prepare solution A.

[0033] 3g of Co (NO3) 2.6H2O is added to 50mL of methanol solution to prepare solution B; then, the A solution is stirred, the B solution is slowly and uniformly added to the A solution, after the addition is completed, the stirring is continued for 1h to prepare the mixed and uniform reaction liquid C.

[0034] The mixed and uniform reaction liquid C is transferred to a 100mL polytetrafluoroethylene lined reaction kettle, a hydrothermal reaction is carried out at 75 DEG C for 135min, after the reaction is completed, the reaction kettle is naturally cooled to room temperature, the precipitated product after the reaction is collected by magnetic separation, and the precipitate is washed with ethanol and dried at 60 DEG C for 6h to prepare the CoFe2O4@ZIF-67 magnetic composite material; CoFe2O4 (cobalt tetraoxo ferrate) is the magnetic core, and ZIF-67 (zeolite imidazole framework-67) is the shell layer.

[0035] The prepared CoFe2O4@ZIF-67 magnetic composite material is characterized by scanning electron microscopy; wherein, the micro surface morphology and particle size distribution of the magnetic core CoFe2O4 and the magnetic composite material CoFe2O4@ZIF-67 with core-shell structure are as shown in Figure 1 .

[0036] From Figure 1 (a), it can be known that the magnetic core CoFe2O4 is a rough surface spherical shape, from Figure 1 (b), it can be known that the rough surface of the magnetic core CoFe2O4 is composed of regular cubic structure and irregular small particles, so that the specific surface area of the core body can be effectively increased to provide sufficient coating sites for ZIF-67; from Figure 1(c)It can be seen that ZIF-67 densely wrapped in the form of small particles on the surface of the core layer, Figure 1 (d)It can be seen that the shape of ZIF-67 is regular dodecahedron, which is distributed on the surface of the magnetic core CoFe2O4, and such structural characteristics avoid the problem of ZIF-67 agglomeration, and present an ideal core-shell structure.

[0037] Therefore, the magnetic composite material disclosed in the embodiment can effectively increase the specific surface area of the material through the core-shell structure of CoFe2O4@ZIF-67, thereby increasing the contact area with the electrolyte and providing more active centers, which is conducive to the adsorption of lead ions and improves the electrochemical performance; at the same time, the preparation method disclosed in the embodiment has the advantage of simple operation.

[0038] Example 2

[0039] The working electrode for the electrochemical sensor is prepared, which comprises the following steps:

[0040] The glassy carbon electrode (GCE for short) with magnetism is polished smooth on the chamois leather with 1.0 μm, 0.3 μm and 0.05 μm polishing powder in turn, and then cleaned alternately with distilled water and anhydrous ethanol by ultrasonic cleaning; then, the washed glassy carbon electrode is placed in a 0.5 mol / L H2SO4 solution and activated by cyclic voltammetry (CV); the activated glassy carbon electrode is placed in a 5 mmol / L K3[Fe(CN)6] solution (containing KCl, concentration is 0.1 mol / L) for CV test, and the difference between the oxidation and reduction peak potentials is not more than 80 mV in the voltage range of-0.2-0.8 V, which is the treated glassy carbon electrode; it should be noted that the glassy carbon electrode with magnetism is an electrode with existing structure, also known as a magnetic glassy carbon electrode, which usually has a magnet or other magnetic structure in the interior or end of the glassy carbon electrode.

[0041] The CoFe2O4@ZIF-67 magnetic composite material prepared in Example 1 is ground into powder and dispersed in deionized water to form a suspension, and then the suspension is drop-coated on the surface of the treated magnetic glassy carbon electrode and dried under an infrared lamp, thereby preparing a CoFe2O4@ZIF-67 / GCE working electrode.

[0042] Preferably, in order to prevent the CoFe2O4@ZIF-67 adsorbed and fixed on the working surface of the magnetic glassy carbon electrode from falling off by magnetic force, a Nafion (perfluorosulfonic acid resin) film can also be coated on the surface of the CoFe2O4@ZIF-67 / GCE working electrode, so that the CoFe2O4@ZIF-67 material adsorbed and fixed on the electrode surface can be well protected and reinforced by the coated Nafion film, which is conducive to prolonging the service life of the CoFe2O4@ZIF-67 / GCE working electrode.

[0043] The specific steps are: drop-coat a Nafion film solution (mass fraction of 5%) on the surface of the CoFe2O4@ZIF-67 / GCE working electrode, and place it under an infrared lamp for drying. After drop-coating and drying, a CoFe2O4@ZIF-67 / Nafion / GCE working electrode is prepared. It should be noted that the Nafion film solution is a product that can be directly purchased on the market, and this embodiment will not be described in detail.

[0044] Example 3

[0045] Electrochemical performance test

[0046] The electrochemical performance test was evaluated by an externally connected CHI660E electrochemical workstation. Among them, the CoFe2O4@ZIF-67 / GCE prepared in Example 2 was used as the working electrode, Ag / AgCl was used as the reference electrode, and platinum wire was used as the counter electrode. The three electrodes were respectively connected to the three electrode connection terminals of the CHI660E electrochemical workstation, and CV test and differential pulse voltammetry (DPV) test were performed.

[0047] The CV test was completed in a 5 mmol / L K3[Fe(CN)6] solution (containing KCl, concentration of 0.1 mol / L) electrolyte, the voltage range was -0.2-0.8 V, and the scan rate was 50 mV / s. The differential pulse voltammetry (DPV) test was completed in an electrolyte containing Pb 2+ , 0.1 mol / L HAc-NaAc (ABS) buffer solution, the test potential interval was -0.9 to -0.1 V, the amplitude was 50 mV, and the pulse width was 0.2 s. All experimental operations were carried out at room temperature. At the same time, CV test and DPV test were used to compare the electrochemical performance of different modified electrodes: Bare / GCE, ZIF-67 / GCE, CoFe2O4 / GCE, CoFe2O4@ZIF-67 / GCE.

[0048] As Figure 2The CV test curves of each electrode are shown, and the test results show that the redox peaks of ZIF-67 / GCE, CoFe2O4 / GCE and CoFe2O4@ZIF-67 / GCE are all increased compared with Bare / GCE; and according to the larger redox peak area and smaller redox potential difference, the conductivity of the electrochemical surface is known, that is, the conductivity of CoFe2O4 / GCE is the best, the conductivity of CoFe2O4@ZIF-67 / GCE is better than that of ZIF-67 / GCE, and close to the conductivity of CoFe2O4 / GCE, and the conductivity of Bare / GCE is the worst; in addition, the peak ratio of the oxidation peak current to the reduction peak current of CoFe2O4@ZIF-67 / GCE is also close to 1, indicating that it also has good electron transfer reversibility.

[0049] As shown in Figure 3 , the DPV test curves of each electrode are shown, and the test results show that the current response signal of CoFe2O4@ZIF-67 / GCE is significantly improved compared with Bare / GCE, CoFe2O4 / GCE and ZIF-67 / GCE, because the functional groups such as -COOH and -OH on the surface of CoFe2O4@ZIF-67 can effectively adsorb Pb 2+ , and the contact area of the composite material increases, providing more adsorption active sites, which can effectively accumulate Pb 2+ , so that more Pb 2+ is deposited on the electrode surface, thereby enhancing the electrochemical response performance.

[0050] At the same time, the electrode performance comparison of CoFe2O4@ZIF-67 / Nafion / GCE is also increased in the DPV test, and according to Figure 3 the test curve, the current response signal of CoFe2O4@ZIF-67 / Nafion / GCE is also better than that of CoFe2O4@ZIF-67 / GCE.

[0051] Example 4

[0052] Stability and reproducibility test

[0053] CoFe2O4@ZIF-67 / Nafion / GCE was subjected to seven times of DPV test in an electrolyte containing 1×10 -5 mol / L of Pb 2+ in a week (0.1 mol / L ABS buffer, pH=4.5), and the test results are shown in Figure 4 (a) and (b).

[0054] Among them, according to Figure 4 (a), it can be seen that the Pb2+ The peak current gradually decreased, which might be due to a small amount of material loss during repeated experiments and storage of the electrode, thus the peak current showed a downward trend, but the current response remained above 93.1% of the initial current, and the current response after one week could still maintain 91.10% of the initial current, which indicated that the CoFe2O4@ZIF-67 / Nafion / GCE had good stability; according to the current intensity change in the DPV in Figure 4 (b) It can be seen that the seven measurement results of the CoFe2O4@ZIF-67 / Nafion / GCE were basically similar, which indicated that the electrode modified by the material had good reproducibility.

[0055] At the same time, the stability and reproducibility of CoFe2O4@ZIF-67 / GCE were tested by the same method, and the test results showed that CoFe2O4@ZIF-67 / GCE also had good stability and reproducibility, but compared with CoFe2O4@ZIF-67 / Nafion / GCE, it was slightly worse, which might be due to the fact that CoFe2O4@ZIF-67 material was adsorbed and fixed on the surface of the magnetic glassy carbon electrode by magnetic force, so a small amount of material might be separated over a long period of time, resulting in a decrease in the performance of the electrode.

[0056] Five

[0057] Anti-interference test

[0058] In actual detection, there are often many interfering ions coexisting with Pb 2+ in the to-be-tested solution, which will affect the detection ability of CoFe2O4@ZIF-67 / GCE; therefore, the anti-interference ability test of CoFe2O4@ZIF-67 / GCE was carried out. In the to-be-tested solution containing 1×10 -5 mol / L of Pb 2+ , 50 times of Zn 2+ , Ni 2+ , Fe 3+ , Co 2+ , Mn 2+ , Cr 3+ , 20 times of Cd 2 + , Cu 2+ and 10 times of Hg 2+ were added for DPV test, and the measurement structure is shown in Figure 5

[0059] According to the DPV current intensity change in Figure 5 , compared with other metal ions, Cu 2+ had a greater impact on Pb 2+ ​The influence of Cu is relatively large, making the peak current decrease by 10.42%, because Cu 2+ competes with Pb 2+ , Cu 2+ will snatch the active sites on CoFe2O4@ZIF-67 / GCE, thereby reducing the current response of Pb 2+ ; the influence of Zn 2+ , Ni 2+ , Fe 3+ , Co 2+ , Mn 2+ , Cr 3+ , Cd 2+ and other metal ions on Pb 2+ is relatively small, and the current response changes are all less than 5%; therefore, it is shown that CoFe2O4@ZIF-67 / GCE has good anti-interference performance and good specificity for Pb 2+ .

[0060] Embodiment 6

[0061] Please refer to Figure 6 , the embodiment discloses an electrochemical device, the disclosed electrochemical device comprises: a shell 100, a micro electrochemical workstation 160, a liquid feeding device and an electrochemical sensor; the shell 100 is provided with a detection chamber 102, a mounting cavity and a liquid inlet 101; the mounting cavity provides a setting space for the installation and fixation of the liquid feeding device in the shell 100, so that the liquid feeding device can be installed and fixed in the mounting cavity to realize hidden setting, and the integration of various structural designs in the shell is realized, thereby making the electrochemical device have the advantages of small size, convenient carrying and simple operation.

[0062] At the same time, the liquid inlet end of the liquid feeding device communicates with the liquid inlet 101, and the liquid outlet end of the liquid feeding device communicates with the detection chamber 102, and the liquid feeding device can transport the to-be-detected liquid into the detection chamber 102. Usually, the liquid feeding device can select an existing micro water pump, but preferably a micro peristaltic pump 120, so that not only the automatic transportation of the to-be-detected liquid can be realized, but also the transportation amount of the to-be-detected liquid can be precisely controlled, which is beneficial to improve the accuracy of the detection structure.

[0063] The micro electrochemical workstation 160 is arranged in the shell 100 and connected with the electrochemical sensor; the electrochemical sensor is a three-electrode system, which usually comprises a reference electrode 140, a counter electrode 150 and a working electrode 130; specifically, the working electrode 130 is a glassy carbon electrode GCE with magnetism, the reference electrode 140 is an existing Ag / AgCl electrode, and the counter electrode 150 is an existing platinum wire electrode.

[0064] The liquid to be tested sent into the detection chamber 102 can be subjected to relevant electrochemical reactions through the working electrode 130, and the qualitative and quantitative analysis of lead ions can be quickly realized through the micro electrochemical workstation 160 in cooperation with the reference electrode 140 and the counter electrode 150; it should be noted that the structure and principle of the above-mentioned micro electrochemical workstation 160 belong to the prior art, and will not be described here.

[0065] The shell 100 is also provided with a material port, which is in communication with the detection chamber 102 and has an open state and a closed state. The structure for switching the open state and the closed state of the material port can adopt the existing rotating or sliding opening and closing structure, and this embodiment will not be described here. When the material port is in the open state, the liquid to be tested in the detection chamber 102 can be discharged through the material port, and the buffer solution and the like can be added into the detection chamber 102 through the material port, such as phosphate buffer solution or ABS buffer solution.

[0066] In order to avoid the influence of impurities in the liquid to be tested on the detection result, a filtering structure 110 such as a filter screen or a filter membrane can be arranged at the liquid inlet 101, and the filter membrane is preferred to better filter out solid impurities. It can be easily understood that in order to ensure the filtering effect, the number of layers can be multiple. In addition, the part of the shell 100 located at the liquid inlet 101 is preferably designed in a tapered structure with a narrow front and a wide back, so that the shell can be avoided to block when the liquid to be tested is extracted, and it is easier to insert into the liquid to be tested for sampling.

[0067] In the embodiment, in order to avoid the phenomenon of back suction and the like affecting the liquid sending precision of the micro peristaltic pump 120, a one-way valve 121 is preferably arranged at the liquid outlet end of the micro peristaltic pump 120. The one-way valve 121 can ensure the normal delivery of the liquid to be tested from the micro peristaltic pump 120 to the detection chamber 102, and prevent the backflow of the liquid to be tested from the detection chamber 102 to the micro peristaltic pump 120.

[0068] Example 7

[0069] The electrochemical device in Example 6 is used to detect the Pb 2+ concentration in the actual sample, and the recovery rate is used as the judgment standard. The specific processing process is as follows:

[0070] Selection of liquid to be tested: After the lake water or river water is static for 48 h, the upper clear liquid is taken, part of the upper clear liquid is filtered through a 0.22 m filter membrane, and the lead ion content in the actual sample is detected by ICP-OES; part of the upper clear liquid is diluted 20 times with ABS (pH = 4.5) buffer solution, and 1 mol / L Pb 2+ and 10 mol / L Pb 2+ samples are prepared by the standard addition method. The samples are used as the liquid to be tested for concentration measurement.

[0071] Detection process: open the one-way valve 121, start the peristaltic pump to suck a certain amount of detection solution into the detection chamber 102; then, close the one-way valve 121, and then close the peristaltic pump switch, so that CoFe2O4@ZIF-67 or CoFe2O4@ZIF-67 / Nafion in the detection chamber is fully adsorbed and combined with the to-be-detected solution; the excess to-be-detected solution is released through the material port, and buffer solution is added in the detection chamber 102 to keep the pH of the detection environment stable, so as to avoid affecting the subsequent detection results due to the change of pH; then, the micro electrochemical workstation 160 switch is turned on, and the lead ion concentration detection is performed; according to the relationship between the heavy metal ion Pb 2+ concentration and the peak current change, a linear regression equation can be constructed to obtain the heavy metal ion Pb 2+ concentration in the to-be-detected solution.

[0072] The detection results are shown in Table 1. Figure 7 As shown in Table 1, the detection results of the standard concentration of Pb 2+ by the electrochemical device are basically consistent with the ICP-OES detection results, the linear equation I (μA) = 1.36978c (μM) + 0.38326, the linear correlation coefficient is 0.99996, the detection limit (LOD) is calculated as 9.3738 x 10 -9 M (S / N = 3), the sensitivity is 32.17 μA·mM -1 ·cm -2 , and the recovery rate of the river water and the lake water is between 99.51-103.42%, and the RSD value is less than 5%; therefore, it has broad application prospects in accurately detecting Pb 2+ in actual samples.

[0073] It is easy to understand that the electrochemical device disclosed in the above embodiment 6 can replace the working electrode with a CoFe2O4@ZIF-67 / Nafion / GCE working electrode or a CoFe2O4@ZIF-67 / GCE working electrode as other implementable ways; in this way, the operation of adding CoFe2O4@ZIF-67 or CoFe2O4@ZIF-67 / Nafion into the detection chamber during the detection process can be avoided, so that the detection operation of the electrochemical device is simpler. At the same time, according to the detection requirements of other heavy metal ions such as mercury, cadmium and chromium, the working electrode, the reference electrode and the counter electrode in embodiment 6 can also be replaced by other corresponding electrodes to complete the detection of the corresponding heavy metal ions.

[0074] The differences between the various embodiments are mainly described in the above embodiments of the utility model, and the different optimization features between the various embodiments can be combined to form a better embodiment without contradiction. Considering the simplicity of writing, it will not be repeated here.

[0075] The above merely describes the embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. An electrochemical device for detecting heavy metal ions, characterized in that, The device includes a housing, a micro electrochemical workstation, a liquid delivery device, and an electrochemical sensor. The housing has a detection chamber, a mounting cavity, a liquid inlet, and a material outlet. The liquid delivery device is mounted and fixed in the mounting cavity, with its inlet end connected to the liquid inlet and its outlet end connected to the detection chamber. The micro electrochemical workstation is located in the housing and connected to the electrochemical sensor. The electrochemical sensor includes a working electrode, a reference electrode, and a counter electrode, all of which are located in the detection chamber. The material outlet is connected to the detection chamber and has an open and a closed state. A filter structure is located at the liquid inlet.

2. The electrochemical device according to claim 1, characterized in that, The detection chamber contains CoFe2O4@ZIF-67 magnetic composite material or CoFe2O4@ZIF-67 / Nafion magnetic composite material for lead ion detection; the working electrode is a magnetic electrode.

3. The electrochemical device according to claim 1, characterized in that, The working electrode is an electrode with the substrate reaction end surface modified with CoFe2O4@ZIF-67 or CoFe2O4@ZIF-67 / Nafion, used for the detection of lead ions.

4. The electrochemical device according to claim 3, characterized in that, The working electrode is either a CoFe2O4@ZIF-67 / GCE electrode or a CoFe2O4@ZIF-67 / Nafion / GCE electrode; wherein, GCE is used as a magnetic glassy carbon electrode as the substrate.

5. The electrochemical device according to claim 4, characterized in that, The reference electrode is an Ag / AgCl electrode, and the counter electrode is a platinum wire electrode.

6. The electrochemical device according to any one of claims 1 to 5, characterized in that, The liquid delivery device is a miniature peristaltic pump.

7. The electrochemical device according to claim 6, characterized in that, The micro peristaltic pump is equipped with a check valve at its outlet.

8. The electrochemical device according to any one of claims 1 to 5, characterized in that, The portion of the housing located at the liquid inlet has a tapered structure that is narrower at the front and wider at the back.

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