Miniaturized heavy metal electrochemical detection device and application thereof

Abstract

The invention discloses a miniaturized heavy metal electrochemical detection device and application thereof, the device comprises a detection pool, a reaction chamber in the detection pool, a circulating pump for conveying a heavy metal solution to be detected into the reaction chamber, a screen-printed electrode arranged in the reaction chamber, and an electrochemical workstation connected with the screen-printed electrode, and the controller is connected to the electrochemical workstation. Compared with a conventional electrochemical detection device, the miniaturized heavy metal electrochemical detection device disclosed by the invention has the advantages of portability, simplicity in operation, capability of quickly detecting on site, short detection time, high detection precision, strong anti-interference capability and the like, is a novel electrochemical detection device which can be widely used, and can be used for quickly and accurately detecting heavy metal ions in a solution; the method is of great significance in enhancing effective monitoring of heavy metal pollutants and reducing harm of heavy metal ion pollution to human beings.

Description

Technical Field

[0001] The present invention belongs to the technical field of portable electrochemical devices and relates to a portable electrochemical device for rapid on-site detection of heavy metal ions, and in particular to a miniaturized heavy metal electrochemical detection device and its application. Background Art

[0002] Continued industrialization has resulted in the release of numerous heavy metal pollutants from industrial waste into the natural environment. These heavy metal pollutants can pose a threat to human health. For example, unlike organic compounds, heavy metal ions are non-biodegradable and readily accumulate in the human body through the food chain. Furthermore, most known heavy metal ions are toxic even at trace concentrations. Furthermore, once in water, heavy metal ions are difficult to remove, exacerbating the pollution problem. Therefore, to mitigate heavy metal ion pollution and reduce its harm to humans, enhanced monitoring of heavy metal pollutants is necessary.

[0003] At present, traditional methods for detecting heavy metal ions include inductively coupled plasma mass spectrometry, atomic absorption spectrometry, X-ray fluorescence spectrometry and atomic emission spectrometry. However, most of the above-mentioned prior arts have defects such as complexity, time-consuming and expensiveness, making them difficult to be applied to the detection of heavy metal pollutants. In recent years, electrochemical detection technology has been widely used to detect heavy metal ions in water bodies due to its low cost, short response time and simple detection process. Among them, the use of miniaturized electrochemical detection devices to achieve on-site use and rapid detection is a research hotspot. However, the electrochemical workstations used in existing electrochemical detection devices have shortcomings such as large size and complex operation, which are not convenient for on-site use and rapid detection. In addition, in existing electrochemical detection devices, the heavy metal solution to be measured is usually first added dropwise to the working electrode surface of the electrochemical sensor, and then a pre-set voltage wave is applied to the working electrode by the electrochemical workstation to form a measurement signal, thereby completing the detection of heavy metal ions in the heavy metal solution to be measured. It can be seen that for the electrochemical detection device, the working electrode and the reaction chamber for processing the heavy metal solution to be measured are very important core components. However, the electrochemical performance of the screen-printed electrodes used in existing electrochemical detection devices is poor, making it difficult to accurately detect heavy metals in water. Even if functional materials are deposited on the working electrode surface of the screen-printed electrode, there are still defects such as small specific surface area, few active sites, easy agglomeration, and poor stability. As a result, the electrochemical detection device constructed in this way still has defects such as small detection linear range, long detection time, and low sensitivity, making it difficult to obtain more accurate heavy metal concentration data. In particular, when the heavy metal concentration in the water body is high, the existing electrochemical detection device cannot be applied. In the existing electrochemical detection device, no reaction chamber is set, and the heavy metal solution to be tested needs to be manually added to the working electrode surface. It is subject to the uncontrollable influence of human operation, which not only leads to poor consistency in the detection results of repeated tests, but also easily leads to poor accuracy of the detection results. In particular, it is difficult to achieve rapid detection of samples. In addition, existing miniaturized heavy metal detectors mainly use ion-selective electrodes, which have poor anti-interference capabilities; heavy metal ion test strips, which have high detection limits and poor precision; and miniaturized electrochemical detectors, which use electrodes made of non-specific materials, which have shortcomings such as poor detection accuracy and poor anti-interference capabilities. Therefore, obtaining a miniaturized heavy metal electrochemical detection device that is simple to operate, can quickly detect on-site, has a short detection time, and high detection accuracy is of great significance for strengthening the effective monitoring of heavy metal pollutants and reducing heavy metal ion pollution and the harm it causes to humans. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a miniaturized heavy metal electrochemical detection device and its application that is simple to operate, can be quickly detected on site, has a short detection time, high detection accuracy, strong anti-interference ability, and is portable.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A miniaturized heavy metal electrochemical detection device, comprising:

[0007] A detection cell for detecting a heavy metal solution to be detected; the detection cell is provided with a reaction chamber for storing the heavy metal solution to be detected;

[0008] A circulation pump, used for delivering the heavy metal solution to be tested into the reaction chamber;

[0009] The reaction chamber is provided with a detachably mounted screen-printed electrode; the screen-printed electrode is connected to an electrochemical workstation; and the electrochemical workstation is connected to a controller.

[0010] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved, wherein the reaction chamber is annular; a water inlet and a water outlet are provided on the reaction chamber; the water inlet and the water outlet are arranged opposite to each other; the water inlet direction of the water inlet is the same as the water outlet direction of the water outlet; the water inlet direction of the water inlet is tangent to the inner wall of the reaction chamber; the water outlet direction of the water outlet is tangent to the inner wall of the reaction chamber; the water inlet is connected to the circulation pump through a pipe; and a filter is provided on the pipe at the water inlet end of the circulation pump.

[0011] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved in that the working electrode of the screen-printed electrode is arranged in the reaction chamber; and the working electrode is electrically connected to the electrochemical workstation via a wire.

[0012] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved, wherein the reaction end surface of the working electrode is loaded with a zirconium-based metal-organic framework composite material; the zirconium-based metal-organic framework composite material includes a zirconium-based metal-organic framework, and the surface of the zirconium-based metal-organic framework is modified with a polydopamine coating; the thickness of the polydopamine coating is nanometer-scale; the zirconium-based metal-organic framework is UiO-66.

[0013] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved in that a method of loading a zirconium-based metal-organic framework composite material on the reaction end surface of the working electrode comprises the following steps:

[0014] S1. Preparing a zirconium-based metal-organic framework: dispersing zirconium chloride and terephthalic acid in N,N-dimethylformamide, adding ethanol, and stirring until completely dissolved to obtain a precursor solution; placing the precursor solution in a reaction kettle, and maintaining it at 100° C. to 150° C. for 18 h to 24 h to obtain a zirconium-based metal-organic framework; the mass ratio of the terephthalic acid to the zirconium chloride is 1 to 1:2; the volume ratio of the ethanol to the N,N-dimethylformamide is 1:1 to 2;

[0015] S2. Dispersing a zirconium-based metal-organic framework into an aqueous solution, adding a dopamine aqueous solution, and stirring for 30 minutes to obtain a zirconium-based metal-organic framework composite material; the mass ratio of the zirconium-based metal-organic framework to the dopamine in the dopamine aqueous solution is 1:1-3;

[0016] S3, dispersing the zirconium-based metal-organic framework composite material into a mixed solution of naphthol and ethanol, and ultrasonicating for 30 minutes to obtain a mixed solution;

[0017] S4. Drop the mixed solution on the working electrode of the screen-printed electrode and dry it at 60° C. to obtain a working electrode with a zirconium-based metal-organic framework composite material loaded on the reaction end surface.

[0018] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved in that the electrochemical workstation is connected to the controller via a wireless connection, a Bluetooth connection or a wired connection.

[0019] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved in that the electrochemical workstation is a portable electrochemical workstation; and the controller is a mobile phone.

[0020] The above-mentioned miniaturized heavy metal electrochemical detection device is further improved and further includes a shell, which includes a supporting bottom and a cover plate; the circulating pump, detection cell and electrochemical workstation are horizontally arranged on the supporting bottom.

[0021] As a general technical concept, the present invention also provides an application of the above-mentioned miniaturized heavy metal electrochemical detection device in detecting heavy metal ions in water.

[0022] The above application is further improved, and the application includes the following steps:

[0023] (1) Turn on the circulation pump to deliver the heavy metal solution to be measured into the reaction chamber, so that the screen-printed electrode is immersed in the heavy metal solution to be measured;

[0024] (2) turning on the electrochemical workstation and adjusting the output voltage of the electrochemical workstation by sending instructions through the controller, so that the heavy metal solution to be measured in the reaction chamber undergoes an electrochemical reaction and obtains a peak current of the heavy metal solution to be measured;

[0025] (3) The peak current of the heavy metal solution to be measured is input into the controller, and the heavy metal ion concentration in the heavy metal solution to be measured is calculated by combining the preset linear regression equation of the heavy metal ion concentration and the peak current.

[0026] The above application is further improved in that, in step (2), the output voltage of the electrochemical workstation is 0.5V; the time of the electrochemical reaction is 100s to 400s;

[0027] The above application is further improved. In step (3), when the heavy metal solution to be measured is a water body containing divalent manganese ions, the linear regression equation of the divalent manganese ion concentration and the peak current is shown in formula (1) or formula (2):

[0028] y= 0.014×x- 0.0713 (1),

[0029] In formula (1), y is the peak current of the solution to be tested, in μA; x is the Mn 2+ The concentration value is in ppb; the linear range of detection is 4 ppb to 100 ppb; the detection limit is 0.22 ppb; the correlation coefficient R 2 =0.99;

[0030] y=7.4143×x+1.0431 (2),

[0031] In formula (2), y is the peak current of the solution to be tested, in μA; x is the Mn 2+ The concentration value is in ppm; the detection linear range is 0.1ppm to 1ppm; the correlation coefficient R 2 =0.99.

[0032] In the present invention, the unit M refers to mol / L.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] (1) In view of the defects of existing electrochemical detection devices such as complex operation, long detection time, high detection cost, poor precision, and difficulty in achieving rapid on-site detection, the present invention creatively proposes a miniaturized heavy metal electrochemical detection device. By integrating the reaction chamber for storing the heavy metal solution to be tested and the screen-printed electrode in the detection cell, and combining the detection cell, circulation pump, and electrochemical workstation together, the volume of the detection device can be significantly reduced, making the detection device more compact and cost-effective, and suitable for large-scale preparation. In this way, a portable miniaturized heavy metal electrochemical detection device can be constructed, so that the miniaturized heavy metal electrochemical detection device can be carried to the detection site for on-site detection of the heavy metal solution to be tested; more importantly, under the joint action of various components, the loading, detection and unloading processes can be completed quickly, so that the concentration data of the heavy metal solution to be tested can be obtained in a timely and accurate manner. Compared with conventional electrochemical detection devices, the miniaturized heavy metal electrochemical detection device of the present invention has the advantages of portability, simple operation, rapid on-site detection, short detection time, high detection accuracy, and strong anti-interference ability. It is a new type of electrochemical detection device that can be widely used and can be used to quickly and accurately detect heavy metal ions in solutions. It is of great significance for strengthening the effective monitoring of heavy metal pollutants and reducing the harm of heavy metal ion pollution to humans.

[0035] (2) In the miniaturized heavy metal electrochemical detection device of the present invention, the reaction chamber used is annular, such as a racetrack-shaped reaction chamber. Using it as the heavy metal detection area can effectively prevent the generation of bubbles when the heavy metal solution to be tested enters the reaction chamber, thereby helping to improve the detection accuracy of the device.

[0036] (3) In response to the shortcomings of the working electrodes of existing electrochemical sensors, such as few adsorption sites, easy agglomeration, and poor water stability, as well as the resulting defects of the electrochemical sensors, such as small detection linear range, slow response speed, poor detection sensitivity, poor detection accuracy, and short service life, the present invention creatively proposes a screen-printed electrode, including a working electrode, and a zirconium-based metal-organic framework composite material is loaded on the reaction end surface of the working electrode, wherein the zirconium-based metal-organic framework composite material includes a zirconium-based metal-organic framework, the surface of the zirconium-based metal-organic framework is modified with a polydopamine coating, the thickness of the polydopamine coating is nanometer-level, and the zirconium-based metal-organic framework is UiO-66. In the present invention, a nanometer-thick polydopamine coating is modified on the surface of UiO-66. On the one hand, since the thickness of the polydopamine coating is nanometer-thick, the original octahedral structure of UiO-66 can be maintained, thereby retaining its high specific surface area, porosity, large pore volume, and the number of open metal sites. On the other hand, since PDA contains rich amine and catechol functional groups, after the PDA coating is formed on the surface of UiO-66, the water stability of UiO-66 can be enhanced and its conductivity, hydrophilicity and manganese ion adsorption capacity can be improved, such as UiO-66@PDA adsorption of Mn 2+ The ability is stronger than that of UiO-66, which overcomes the problem of screen-printed electrodes directly detecting low concentrations of Mn in water. 2+ The problem of Mn 2+ The adsorption capacity of the screen-printed electrode is conducive to the adsorption of high concentration Mn 2+ Accurate detection of UiO-66 is possible. In particular, the significantly enhanced water stability of UiO-66 allows the screen-printed electrode to be stored for a long time, and the measurement error after 30 days is very small, overcoming the problem of long-term storage of screen-printed electrodes. More importantly, the polydopamine coating is modified on the surface of UiO-66, making the surface of the zirconium-based metal-organic framework composite material have abundant active sites, showing stronger electrochemical activity, and the effect of Mn 2+ The electrochemical detection has the characteristics of high sensitivity and rapid response. On this basis, the present invention loads UiO-66 with a surface modified with polydopamine coating on the working electrode surface of the screen-printed electrode to construct a miniaturized heavy metal electrochemical detection device. The miniaturized heavy metal electrochemical detection device can use the square wave voltammetry (SWV) of the electrochemical workstation to perform cathode stripping voltammetry (CSV) test, and can complete the Mn 2+ Deposition and stripping, such as the deposition stage can be Mn 2+ Oxidation to Mn 4+ , a layer of MnO2 is formed on the surface of the working electrode, and the Mn 4+ Reduced to Mn 2+ Leave the electrode, especially when the system contains Mn 2+When Mn is present, the sample shows a peak value at a voltage of 0.5 V after the reaction, and the peak current increases with the increase of Mn 2+ The concentration of Mn increases, so it can be established 2+ The linear relationship between the concentration and the peak current is detected, and the Mn content in the heavy metal solution to be tested is calculated based on the linear regression equation. 2+ concentration, and finally the Mn 2+ Compared with conventional electrochemical detection devices, the miniaturized heavy metal electrochemical detection device constructed based on composite materials has the following advantages: (a) wide linear detection range, which can be used to detect Mn with a concentration of 4ppb-1ppm 2+ ; (b) High sensitivity to Mn 2+ (c) Rapid response, capable of detecting low concentrations of Mn in water within 100 seconds. 2+ (d) It has a long service life and the measurement results have a small error after 30 days of storage; (e) It has the advantages of simple operation, low cost, miniaturization and portability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0038] Figure 1 This is a schematic structural diagram of a miniaturized heavy metal electrochemical detection device in Example 1 of the present invention.

[0039] Figure 2 Schematic diagram of the structure of the detection cell in Example 1 of the present invention.

[0040] Figure 3 This is an SEM image of the zirconium-based metal-organic framework composite material (UiO-66@PDA) prepared in Example 1 of the present invention.

[0041] Figure 4 The miniaturized heavy metal electrochemical detection device in Example 1 of the present invention is Mn 2+ The linear fitting standard curve corresponding to the concentration range of 4 ppb to 100 ppb.

[0042] Figure 5 The miniaturized heavy metal electrochemical detection device in Example 1 of the present invention is Mn 2+ The linear fitting standard curve corresponding to the concentration range of 0.1ppm to 1ppm.

[0043] Legend:

[0044] 1. Heavy metal solution to be tested; 2. Circulation pump; 3. Detection cell; 31. Reaction chamber; 32. Screen-printed electrode; 33. Water inlet; 34. Water outlet; 4. Wires; 5. Electrochemical workstation; 6. Controller. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby.

[0046] Example 1

[0047] like Figure 1 and Figure 2 As shown, the miniaturized heavy metal electrochemical detection device of this embodiment includes:

[0048] The detection pool 3 is used to detect the heavy metal solution 1 to be tested; the detection pool 3 is provided with a reaction chamber 31 for storing the heavy metal solution 1 to be tested;

[0049] A circulation pump 2, used for delivering the heavy metal solution 1 to be tested into the reaction chamber 31;

[0050] A detachable screen-printed electrode 32 is provided in the reaction chamber 31 ; the screen-printed electrode 32 is connected to an electrochemical workstation 5 ; and the electrochemical workstation 5 is connected to a controller 6 .

[0051] In this embodiment, the reaction chamber 31 is annular, and is provided with a water inlet 33 and a water outlet 34. The water inlet 33 and the water outlet 34 are arranged opposite to each other, and the water inlet direction of the water inlet 33 is the same as the water outlet direction of the water outlet 34; the water inlet direction of the water inlet 33 is tangent to the inner wall of the reaction chamber 31, and the water outlet direction of the water outlet 34 is tangent to the inner wall of the reaction chamber 31; the water inlet 33 is connected to the circulation pump 2 through a pipe; a filter is provided on the pipe at the water inlet end of the circulation pump 2 to remove impurities in the solution to prevent interference with detection.

[0052] In this embodiment, the working electrode of the screen-printed electrode 32 is disposed in the reaction chamber 31 ; the working electrode is electrically connected to the electrochemical workstation 5 via a wire 4 .

[0053] In this embodiment, the reaction end surface of the working electrode is loaded with a zirconium-based metal-organic framework composite material, the zirconium-based metal-organic framework composite material includes a zirconium-based metal-organic framework, the surface of the zirconium-based metal-organic framework is modified with a polydopamine coating, the thickness of the polydopamine coating is nanometer-scale, and the zirconium-based metal-organic framework is UiO-66.

[0054] In this embodiment, the method for loading a zirconium-based metal-organic framework composite material on the reaction end surface of the working electrode includes the following steps:

[0055] S1. Preparation of zirconium-based metal-organic frameworks:

[0056] According to the mass ratio of terephthalic acid to zirconium chloride of 1:2 and the volume ratio of ethanol to N,N-dimethylformamide of 1:2, zirconium chloride and terephthalic acid are dispersed in N,N-dimethylformamide (DMF), ethanol is added, and stirred until completely dissolved to obtain a precursor solution; the precursor solution is placed in the lining of a reactor and maintained at 120°C for 24 hours to obtain a zirconium-based metal-organic framework, namely UiO-66.

[0057] S2. According to the mass ratio of the zirconium-based metal-organic framework to dopamine in the dopamine aqueous solution of 1:1, the zirconium-based metal-organic framework is dispersed in the aqueous solution, the dopamine aqueous solution is added, and the mixture is stirred for 30 minutes. A layer of polydopamine coating with a nanometer thickness is modified on the surface of the zirconium-based metal-organic framework to obtain a zirconium-based metal-organic framework composite material, namely UiO-66@PDA.

[0058] Figure 3 This is a SEM image of the zirconium-based metal organic framework composite material (UiO-66@PDA) prepared in Example 1 of the present invention. Figure 3 It can be seen that UiO-66@PDA maintains a regular octahedral structure and has a smooth PDA coating on the surface, indicating that UiO-66@PDA was successfully prepared.

[0059] S3, zirconium-based metal organic framework composite material is dispersed in the mixed solution of naphthol and ethanol, ultrasonic 30min, obtains mixed solution.In this mixed solution, the concentration of zirconium-based metal organic framework composite material is 2mg / mL.In this step, the naphthol adopted and the mixed solution of ethanol are prepared after mixing by naphthol and ethanol, and the mass fraction of naphthol in the mixed solution of this naphthol and ethanol is 0.5%.In this step, under the effect of naphthol, zirconium-based metal organic framework composite material can be stably adhered to the surface of electrode, be conducive to improving the stability of electrode, but, when the concentration of naphthol in the mixed solution is too high, zirconium-based metal organic framework composite material can be caused to reunite, thus be difficult to be dispersed in electrode surface, and when concentration is too low, zirconium-based metal organic framework composite material can be caused to stably load in electrode surface.

[0060] S4. Drop the mixed solution onto the working electrode of the screen-printed electrode 32 and dry it at 60° C. to obtain a working electrode with a zirconium-based metal-organic framework composite material loaded on the reaction end surface.

[0061] In this embodiment, the electrochemical workstation 5 and the controller 6 are connected via a wireless connection, a Bluetooth connection, or a wired connection. In this embodiment, the Bluetooth connection is used to connect the electrochemical workstation 5 and the controller 6 .

[0062] In this embodiment, the electrochemical workstation 5 used is a portable electrochemical workstation, which may be EmStat3Blue, but is not limited thereto.

[0063] In this embodiment, the controller 6 is a mobile phone, but is not limited thereto.

[0064] In this embodiment, a shell is further included, which includes a supporting bottom and a cover plate; the circulation pump 2, the detection cell 3 and the electrochemical workstation 5 are horizontally arranged on the supporting bottom.

[0065] In this embodiment, the shell is manufactured as follows:

[0066] (3.1) Use 3D modeling software for modeling and design.

[0067] (3.2) Use slicing software to slice the 3D model.

[0068] (3.3) The housing of the device is manufactured using a fusion-type 3D printer.

[0069] In this embodiment, the detection cell and reaction chamber are manufactured as follows:

[0070] (4.1) Use 3D modeling software for modeling and design.

[0071] (4.2) Use slicing software to slice the 3D model.

[0072] (4.3) Use a surface projection micro-stereolithography printer to manufacture the detection pool and reaction chamber.

[0073] In this embodiment, the miniaturized heavy metal electrochemical detection device consists of a housing, a peristaltic pump, a handle, a portable electrochemical workstation, and a detection cell, with an overall size of 230 mm × 150 mm × 83 mm. The device is powered by a miniaturized battery.

[0074] In this embodiment, the application of the miniaturized heavy metal electrochemical detection device in detecting heavy metal ions in water includes the following steps:

[0075] (1) Turn on the circulation pump 2 to deliver the heavy metal solution 1 to be measured into the reaction chamber 31 , so that the screen-printed electrode 32 is immersed in the heavy metal solution 1 to be measured.

[0076] (2) Turn on the electrochemical workstation 5 and send a command through the controller 6 to adjust the output voltage of the electrochemical workstation 5 to 0.5V, so that the heavy metal solution to be measured in the reaction chamber 31 undergoes an electrochemical reaction for 100 seconds, and obtains the peak current of the heavy metal solution to be measured.

[0077] (3) The peak current of the heavy metal solution to be measured is input into the controller 6, and the concentration of heavy metal ions in the heavy metal solution to be measured is calculated by combining the preset linear regression equation of the divalent manganese ion concentration and the peak current.

[0078] In this embodiment, the linear regression equation of the divalent manganese ion concentration and the peak current is shown in formula (1) or formula (2):

[0079] y= 0.014×x- 0.0713 (1),

[0080] In formula (1), y is the peak current of the solution to be tested, in μA; x is the Mn 2+ The concentration value is in ppb; the linear range of detection is 4 ppb to 100 ppb; the detection limit is 0.22 ppb; the correlation coefficient R 2 =0.99;

[0081] y=7.4143×x+1.0431 (2),

[0082] In formula (2), y is the peak current of the solution to be tested, in μA; x is the Mn 2+ The concentration value is in ppm; the detection linear range is 0.1ppm to 1ppm; the correlation coefficient R 2 =0.99.

[0083] In this embodiment, the method for constructing a linear regression equation of divalent manganese ion concentration and peak current includes the following steps:

[0084] (a) Take different concentrations of Mn 2+ The blank surface water samples were used as divalent manganese ion standard solutions to obtain different concentrations of heavy metal solutions to be tested. The divalent manganese ions (Mn 2+ ) concentrations are 4ppb, 6ppb, 8ppb, 10ppb, 20ppb, 30ppb, 40ppb, 60ppb, 80ppb, 100ppb, 0.15ppm, 0.2ppm, 0.4ppm, 0.6ppm, 0.8ppm, and 1ppm, respectively.

[0085] (b) Different heavy metal solutions to be tested were introduced into the reaction chamber 31 for an electrochemical reaction for 100 s. The peak current of the different heavy metal solutions to be tested was measured. Specifically, a cathode glass voltammetry (CSV) test was performed using square wave voltammetry (SWV). The peak current I of the different heavy metal solutions to be tested at a voltage of 0.5 V after the reaction was recorded.

[0086] (c) Based on the peak current I of different samples, a linear relationship between the divalent manganese ion concentration and the peak current was established, and a linear regression equation between the divalent manganese ion concentration and the peak current was obtained. The results are shown in Figure 2. Figure 4 and Figure 5 shown.

[0087] Figure 4 The miniaturized heavy metal electrochemical detection device in Example 1 of the present invention is Mn 2+ The linear fitting standard curve corresponding to the concentration range of 4 ppb to 100 ppb.

[0088] Figure 5 The miniaturized heavy metal electrochemical detection device in Example 1 of the present invention is Mn 2+ The linear fitting standard curve corresponding to the concentration range of 0.1ppm to 1ppm.

[0089] Depend on Figure 4 and Figure 5 It can be seen that the miniaturized heavy metal electrochemical detection device constructed by the present invention is used to detect Mn 2+ The corresponding detection linear range is 4ppb to 1000ppb, and the detection limit is lower than 1ppb, which is far lower than the international standard of 50ppb.

[0090] From the above results, it can be seen that when the miniaturized heavy metal electrochemical detection device of the present invention is used to detect heavy metal manganese ions, it can quantitatively detect the concentration of manganese ions in water with high sensitivity.

[0091] According to the method in Example 1, a miniaturized heavy metal electrochemical detection device was used to detect Mn in different actual water bodies. 2+ The concentration of the heavy metal solution was different, and other conditions were the same.

[0092] The heavy metal solutions to be tested are four different Mn 2+ concentration of surface water, four different Mn 2+ concentration of soil leachate, six different Mn 2+ concentration of electrolytic manganese slag leachate and three different Mn 2+ To keep the test solution within the detection range of the device of the present invention, the actual water sample can be diluted with 0.1M acetic acid-sodium acetate buffer at pH=5 according to the actual situation before testing. At the same time, the Mn content in different actual water samples was measured by atomic absorption spectrometer. 2+ concentration.

[0093] Table 1 Different detection devices for different actual water Mn 2+ Concentration test results

[0094]

[0095] As shown in Table 1, compared with the detection results of the atomic absorption spectrometer, the detection accuracy of the miniaturized heavy metal electrochemical detection device of the present invention for different actual water samples is above 85%, which shows that the miniaturized heavy metal electrochemical detection device of the present invention is effective for detecting Mn in various water bodies. 2+ The detection has good accuracy.

[0096] Based on the above results, it can be seen that compared with conventional electrochemical detection devices, the miniaturized heavy metal electrochemical detection device of the present invention has the advantages of portability, simple operation, rapid on-site detection, short detection time, high detection accuracy, and strong anti-interference ability. It is a new type of electrochemical detection device that can be widely used and can be used to quickly and accurately detect heavy metal ions in solutions. It is of great significance for strengthening the effective monitoring of heavy metal pollutants and reducing the harm of heavy metal ion pollution to humans.

[0097] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of protection of the present invention are within the scope of protection of the present invention. It should be noted that improvements and modifications that can be made by a person skilled in the art without departing from the principles of the present invention are also considered to be within the scope of protection of the present invention.

Claims

1. A miniaturized heavy metal electrochemical detection device, characterized in that: include: A detection cell (3) is used to detect a heavy metal solution (1) to be detected; a reaction chamber (31) is provided in the detection cell (3) for storing the heavy metal solution (1) to be detected; A circulation pump (2) for delivering the heavy metal solution (1) to be tested into the reaction chamber (31); A detachably mounted screen-printed electrode (32) is provided in the reaction chamber (31); an electrochemical workstation (5) is connected to the screen-printed electrode (32); and a controller (6) is connected to the electrochemical workstation (5).

2. The miniaturized heavy metal electrochemical detection device according to claim 1, characterized in that: The reaction chamber (31) is annular; a water inlet (33) and a water outlet (34) are provided on the reaction chamber (31); the water inlet (33) and the water outlet (34) are arranged opposite to each other; the water inlet direction of the water inlet (33) and the water outlet direction of the water outlet (34) are the same; the water inlet direction of the water inlet (33) is tangent to the inner wall of the reaction chamber (31); the water outlet direction of the water outlet (34) is tangent to the inner wall of the reaction chamber (31); the water inlet (33) is connected to the circulation pump (2) through a pipeline; a filter is provided on the pipeline at the water inlet end of the circulation pump (2).

3. The miniaturized heavy metal electrochemical detection device according to claim 2, characterized in that: The working electrode of the screen-printed electrode (32) is arranged in the reaction chamber (31); the working electrode is electrically connected to the electrochemical workstation (5) via a wire (4).

4. The miniaturized heavy metal electrochemical detection device according to claim 3, characterized in that: The reaction end surface of the working electrode is loaded with a zirconium-based metal-organic framework composite material; the zirconium-based metal-organic framework composite material includes a zirconium-based metal-organic framework, and the surface of the zirconium-based metal-organic framework is modified with a polydopamine coating; the thickness of the polydopamine coating is nanometer-scale; the zirconium-based metal-organic framework is UiO-66.

5. The miniaturized heavy metal electrochemical detection device according to claim 4, characterized in that: The method of loading a zirconium-based metal-organic framework composite material on the reaction end surface of the working electrode comprises the following steps: S1. Preparing a zirconium-based metal-organic framework: dispersing zirconium chloride and terephthalic acid in N,N-dimethylformamide, adding ethanol, and stirring until completely dissolved to obtain a precursor solution; placing the precursor solution in a reaction kettle, and maintaining it at 100° C. to 150° C. for 18 h to 24 h to obtain a zirconium-based metal-organic framework; the mass ratio of the terephthalic acid to the zirconium chloride is 1 to 1:2; the volume ratio of the ethanol to the N,N-dimethylformamide is 1:1 to 2; S2. Dispersing a zirconium-based metal-organic framework into an aqueous solution, adding a dopamine aqueous solution, and stirring for 30 minutes to obtain a zirconium-based metal-organic framework composite material; the mass ratio of the zirconium-based metal-organic framework to the dopamine in the dopamine aqueous solution is 1:1-3; S3, dispersing the zirconium-based metal-organic framework composite material into a mixed solution of naphthol and ethanol, and ultrasonicating for 30 minutes to obtain a mixed solution; S4. Dropping the mixed solution onto the working electrode of the screen-printed electrode (32), and drying the mixture at 60° C., thereby obtaining a working electrode with a zirconium-based metal-organic framework composite material loaded on the reaction end surface.

6. The miniaturized heavy metal electrochemical detection device according to claim 1, characterized in that: The electrochemical workstation (5) and the controller (6) are connected via a wireless connection, a Bluetooth connection, or a wired connection; the electrochemical workstation (5) is a portable electrochemical workstation; and the controller (6) is a mobile phone.

7. The miniaturized heavy metal electrochemical detection device according to any one of claims 1 to 6, characterized in that: It also includes a shell, which includes a supporting bottom and a cover plate; the circulating pump (2), the detection cell (3) and the electrochemical workstation (5) are horizontally arranged on the supporting bottom.

8. Use of the miniaturized heavy metal electrochemical detection device according to any one of claims 1 to 7 in detecting heavy metal ions in water.

9. The use according to claim 8, characterized in that The application comprises the following steps: (1) Turn on the circulation pump (2) to transport the heavy metal solution (1) to be tested into the reaction chamber (31), so that the screen-printed electrode (32) is immersed in the heavy metal solution (1) to be tested; (2) turning on the electrochemical workstation (5), and sending instructions through the controller (6) to adjust the output voltage of the electrochemical workstation (5), so that the heavy metal solution to be measured in the reaction chamber (31) undergoes an electrochemical reaction, and obtains a peak current of the heavy metal solution to be measured; (3) The peak current of the heavy metal solution to be measured is input into the controller (6), and the heavy metal ion concentration in the heavy metal solution to be measured is calculated by combining the preset linear regression equation of the heavy metal ion concentration and the peak current.

10. The use according to claim 9, characterized in that In step (2), the output voltage of the electrochemical workstation (5) is 0.5V; the time of the electrochemical reaction is 100s to 400s; In step (3), when the heavy metal solution (1) to be tested is a water body containing divalent manganese ions, the linear regression equation of the divalent manganese ion concentration and the peak current is shown in formula (1) or formula (2): y= 0.014×x- 0.0713 (1), In formula (1), y is the peak current of the solution to be tested, in μA; x is the Mn 2+ The concentration value is in ppb; the detection linear range is 4ppb to 100ppb; The detection limit is 0.22 ppb; the correlation coefficient R 2 =0.99; y=7.4143×x+1.0431 (2), In formula (2), y is the peak current of the solution to be tested, in μA; x is the Mn 2+ The concentration value, in ppm; The linear range of detection is 0.1ppm~1ppm; the correlation coefficient R 2 =0.99.

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