One-dimensional linear imine covalent organic framework Ta-BTDC-COF materials and their electrochemical sensors and detection methods
A portable electrochemical sensor was prepared by synthesizing Ta-BTDC-COF material via a one-step solvothermal method. This solved the problems of expensive heavy metal ion detection equipment and difficulty in simultaneously detecting Pb(II) and As(V) in the existing technology, and achieved on-site detection with high sensitivity and wide linear range.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YUNNAN UNIV
- Filing Date
- 2023-09-20
- Publication Date
- 2026-07-17
AI Technical Summary
Existing methods for detecting heavy metal ions require expensive equipment and specialized operation, and are not suitable for real-time on-site detection. They also make it difficult to simultaneously and efficiently detect Pb(II) and As(V) in water.
A one-step solvothermal method was used to synthesize a one-dimensional linear imine covalent organic framework Ta-BTDC-COF material, which was then used to prepare a portable electrochemical sensor. Differential pulse voltammetry was used for detection, and the sample solution was directly dropped onto the substrate electrode surface.
It achieves sensitive detection of trace Pb(II) and As(V) in water, with detection limits of 0.5 μg/L and 25 μg/L, respectively. It has a wide detection range, is suitable for rapid on-site detection, and simplifies the operation procedure.
Smart Images
Figure CN117304431B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of heavy metal detection technology, and in particular to a one-dimensional linear imine covalent organic framework Ta-BTDC-COF material and its electrochemical sensor and detection method. Background Technology
[0002] With social development and increased human activity, environmental pollution has become increasingly serious. Heavy metal pollution has become a global problem, posing a serious threat to human health. Currently, heavy metal ion pollution is mainly concentrated in soil pollution, air pollution, solid waste, and especially water pollution.
[0003] Heavy metals refer to those with an atomic density greater than or equal to 5 kg / dm³. 3 Metals such as lead (Pb), cadmium (Cd), and copper (Cu) are also considered toxic. Among these, heavy metals like lead and arsenic may have toxic effects on the central nervous system and produce carcinogenic effects.
[0004] Therefore, there is an urgent need to develop a method that can detect heavy metal ions in water in real time, quickly and accurately.
[0005] Currently, there are many methods for detecting trace heavy metals, including inductively coupled plasma mass spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, and ultraviolet-visible spectrophotometry. However, these methods require expensive equipment, skilled operators, and sufficient workspace. For large-scale detection, the process is time-consuming and labor-intensive, requiring sample pretreatment, making them unsuitable for real-time on-site detection.
[0006] Therefore, the miniaturization and integration of sensors, as well as the portability and automation of analytical instruments, are inevitable trends in the development of heavy metal detection in aquatic environments.
[0007] Covalent organic frameworks (COFs) are framework structures formed by connecting atoms through covalent bonds. Due to their large specific surface area, high porosity, good thermal stability, and tunable framework characteristics, they have attracted widespread attention from scientists in recent years. Imine COFs, in particular, are stable in most organic solvents, water, and even strong acid or strong base solutions. They can also be formed from a wide variety of monomers. Furthermore, these COFs contain more nitrogen and oxygen atoms, allowing them to coordinate with a range of metal ions.
[0008] COFs have broad application prospects and value in many fields such as selective gas separation and storage, heterogeneous catalysis, optoelectronic devices, and biomedicine.
[0009] For example, CN 201810184155.3 discloses a method for preparing a carbon paste electrode modified with a covalent organic framework material. This carbon paste electrode modified with the covalent organic framework material exhibits good response to lead, achieving a lead detection level of 1.03 μM in tap water with a recovery rate of 103%; and a lead detection level of 0.97 μM in lake water with a recovery rate of 102.7%. Furthermore, the detection of heavy metal ions in that application requires adding the heavy metal ion solution to a buffer solution with optimized conditions, while this application allows direct drop-addition of the heavy metal ion solution to the surface of the modified screen-printed electrode for detection, making the method simpler. However, the covalent organic framework electrode disclosed therein cannot simultaneously detect Pb(II) and As(V) in water.
[0010] In addition, since arsenic is a metalloid, it mainly exists in the form of oxygen-containing anions and cannot exist as cations, which also increases the difficulty of its detection.
[0011] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0012] This application addresses the above-mentioned technical problems by providing a one-dimensional linear imine covalent organic framework Ta-BTDC-COF material, its electrochemical sensor, and detection method. An imine covalent organic framework (COF) was synthesized using a one-step solvothermal method. A portable electrochemical sensor modified with this material can achieve sensitive detection of trace Pb(II) and As(V) in water.
[0013] This application provides a one-dimensional linear imine covalent organic framework TA-BTDC-COF material, which, when magnified to 500 nm, has a hollow tubular cluster morphology; it is used to fabricate an electrochemical sensor to detect lead and arsenic ions in water samples.
[0014] An electrochemical sensor based on an imine covalent organic framework TA-BTDC-COF modified matrix electrode has a detection limit of 25 μg / L for arsenic and a detection range of 25 μg / L to 10 mg / L, specifically 25 μg / L, 50 μg / L, 0.1 mg / L, 0.25 mg / L, 0.5 mg / L, 1 mg / L, 3 mg / L, 5 mg / L, and 10 mg / L.
[0015] The detection limit for lead is 0.5 μg / L, and the detection range for lead content is 0.5 μg / L to 1 mg / L, specifically 0.5 μg / L, 1 μg / L, 2.5 μg / L, 5 μg / L, 10 μg / L, 25 μg / L, 50 μg / L, 0.1 mg / L, 0.25 mg / L, 0.5 mg / L, and 1 mg / L.
[0016] Preferably, the mixture is prepared by the following steps: dissolving 4,4-diaminoterphenyl and [2,2'-dithiophene]-5,5'-dicarboxaldehyde in a mixed solvent to obtain a mixed reaction solution;
[0017] Add 1 mL of 9 mol / L acetic acid aqueous solution to the mixed reaction solution, sonicate for 10 min, and react at 120℃ for 72 h to obtain a product containing an imine covalent organic framework TA-BTDC-COF.
[0018] The mixed solvent used was trimethylbenzene:1,4-dioxane in a volume ratio of 1:1.
[0019] Preferably, the process further includes washing and drying the obtained product with acetone to obtain an imine covalent organic framework TA-BTDC-COF;
[0020] Preferably, the acetone washing is performed three times.
[0021] Preferably, the drying conditions are drying at 60°C for 12 hours.
[0022] Specifically, the preparation method of the imine covalent organic framework TA-BTDC-COF is as follows:
[0023] 1) Weigh 52.1 mg Ta (4,4-diaminoterphenyl) and 44.5 mg BTDC ([2,2'-dithiophene]-5,5'-dicarboxaldehyde) and dissolve them in 9 mL of mesitylene / 1,4-dioxane (v:v = 1:1). Then add 1 mL of 9 mol / L acetic acid aqueous solution to the above mixture dropwise, sonicate for 10 min, and then transfer it to a reaction vessel and react at 120 °C for 72 h.
[0024] 2) The collected product was washed three times with acetone, and then dried under vacuum at 60°C for 12 h to obtain Ta-BTDC-COF.
[0025] Another aspect of this application provides an electrochemical sensor, comprising: a substrate electrode, wherein an imine covalent organic framework TA-BTDC-COF as described in any one of claims 1 to 4 is modified and disposed on the substrate electrode, wherein the resulting electrochemical sensor, when used for water sample detection, has a detection limit of 25 μg / L for arsenic and a detection limit of 0.5 μg / L for lead.
[0026] Preferably, the substrate electrode is a screen-printed electrode.
[0027] Preferably, the modification method includes the following steps:
[0028] The powdered imine covalent organic framework TA-BTDC-COF was dispersed in water and sonicated to obtain a suspension.
[0029] The suspension was dropped onto the substrate electrode and dried by infrared irradiation to obtain a substrate electrode modified with an imine covalent organic framework TA-BTDC-COF.
[0030] Specifically, the method for modifying the imine covalent organic framework TA-BTDC-COF is as follows:
[0031] Ta-BTDC-COF was ground into powder, 2 mg was weighed and placed in a centrifuge tube, ultrapure water was added, and the mixture was sonicated for 3 min to obtain a Ta-BTDC-COF suspension. 10 μL of this suspension was transferred by pipette and dropped onto a screen-printed electrode, which was then dried by irradiation with an infrared lamp.
[0032] Another aspect of this application provides a method for detecting heavy metals using the above-mentioned electrochemical sensor, comprising the following steps:
[0033] After the sample solution to be tested is dropped onto the substrate electrode, the result is obtained by differential pulse voltammetry.
[0034] Preferably, when detecting lead content in a sample, heavy metal ions are enriched using a constant potential it curve before detection by differential pulse voltammetry.
[0035] Preferably, the parameters for the constant potential it curve detection are: -1.5V, 200s.
[0036] Preferably, when detecting lead content in a sample, the parameters of the differential pulse voltammetry are: scan range of -1 to -0.4V; amplitude, pulse width, sampling width, pulse period, and equilibration time of 50mV, 0.05s, 0.0167, 0.1s, and 10s, respectively.
[0037] Preferably, when detecting the arsenic content in a sample, the parameters of the differential pulse voltammetry are: a scan range of -0.4 to 0.4 V; and amplitude, pulse width, sampling width, pulse period, and equilibration time of 50 mV, 0.05 s, 0.0167, 0.1 s, and 10 s, respectively.
[0038] The specific electrochemical testing method is as follows:
[0039] 1) The specific method for detecting lead ions is as follows: the sample to be tested is directly dropped onto the surface of the modified screen-printed electrode. First, the heavy metal ions are enriched using a constant potential (it) curve with the following parameters: -1.5V, 200s. Then, the sample is detected using differential pulse voltammetry with the following parameters: scan range of -1 to -0.4V; amplitude, pulse width, sampling width, pulse period, and equilibrium time are 50mV, 0.05s, 0.0167, 0.1s, and 10s, respectively.
[0040] 2) The method for detecting metalloid As(V) is similar to that for lead, except that As(V) does not require enrichment using a constant potential it curve. In addition, its scanning range is -0.4 to 0.4V.
[0041] The beneficial effects that this application can produce include:
[0042] 1) The TA-BTDC-COF provided in this application is prepared using a one-step solvothermal method. This material has a large specific surface area and a large number of active sites. When modified onto the surface of a screen-printed electrode as a substrate electrode, this material can be used for the accurate detection of heavy metal lead and arsenic ions in a portable, highly sensitive, and highly selective manner. The electrochemical sensor made from this material has a detection limit of 25 μg / L for arsenic in water samples and a detection limit of 0.5 μg / L for lead.
[0043] 2) The TA-BTDC-COF provided in this application, when used with the electrochemical sensor made by this invention to detect heavy metal ions, allows the solution containing heavy metal ions to be directly dropped onto the surface of the substrate electrode without the need for the preparation and selection of buffer solutions, thus effectively simplifying the detection steps.
[0044] 3) The electrochemical sensor prepared by TA-BTDC-COF provided in this application is used to determine lead and arsenic heavy metal ions in sample solutions using cyclic voltammetry and differential pulse voltammetry. Verification has shown that this method has high detection sensitivity, a wide linear range, good stability, strong anti-interference ability, and a simple and reliable electrode preparation process with a short detection cycle, making it suitable for rapid on-site detection. The electrochemical sensor provides wide linearity and a satisfactory dynamic range for the detection of arsenic and lead. Attached Figure Description
[0045] Figure 1 SEM and TEM images of the Ta-BTDC-COF material provided in this application; where a) is the SEM image and b) is the TEM image.
[0046] Figure 2 The DPV response curves of the electrochemical sensor provided in this application for detecting samples with different Pb(II) concentrations;
[0047] Figure 3 The electrochemical sensor provided in this application is used to detect the DPV response of samples with different As(V) concentrations. Detailed Implementation
[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.
[0050] Technical means not detailed in this application and not used to solve the technical problems of this application are all set according to common general knowledge in the field, and multiple common general knowledge setting methods can be implemented.
[0051] Example
[0052] Unless otherwise specified, all materials and instruments used in the following examples were obtained through commercial channels.
[0053] Example 1: Preparation of imine-based covalent organic framework TA-BTDC-COF
[0054] 1) Weigh 52.1 mg Ta (4,4-diaminoterphenyl) and 44.5 mg BTDC ([2,2'-dithiophene]-5,5'-dicarboxaldehyde) and dissolve them in 9 mL of mesitylene / 1,4-dioxane (v:v = 1:1). Then add 1 mL of 9 mol / L acetic acid aqueous solution to the above mixture dropwise, sonicate for 10 min, and then transfer it to a reaction vessel and react at 120 °C for 72 h.
[0055] 2) The collected product was washed three times with acetone, and then dried under vacuum at 60°C for 12 h to obtain Ta-BTDC-COF.
[0056] The obtained Ta-BTDC-COF was subjected to transmission electron microscopy and scanning electron microscopy experiments. The SEM images of Ta-BTDC-COF are shown below. Figure 1 As shown. From Figure 1 a) The SEM image shows that Ta-BTDC-COF presents a uniform hollow tubular shape and is combined with Figure 1The TEM image in b further confirms the existence of the hollow tubular structure. The obtained hollow tubular structure can effectively increase the surface area of the material and obtain more active sites, thereby effectively improving the sensitivity and selectivity of heavy metal detection.
[0057] Example 2: Preparation of Electrochemical Sensor
[0058] The Ta-BTDC-COF obtained in Example 1 was ground into powder. 2 mg of the powder was weighed and placed in a centrifuge tube. Ultrapure water was added, and the mixture was sonicated for 3 minutes to obtain a Ta-BTDC-COF suspension. 10 μL of this suspension was transferred using a pipette and drop-coated onto a screen-printed electrode. The electrode was then dried by irradiation with an infrared lamp. The resulting substrate electrode was assembled according to existing electrochemical sensor specifications to obtain the electrochemical sensor.
[0059] Example 3 uses the sensor from Example 2 to detect lead-containing samples.
[0060] The detection method is as follows:
[0061] 1) The sample to be tested is dropped directly onto the surface of the modified screen-printed electrode. The processed sample contains only lead ions, with a lead ion concentration ranging from 25 μg / L to 10 mg / L, as detailed below. Figure 2 As shown.
[0062] 2) Heavy metal ions were enriched using a constant potential it curve with the following parameters: -1.5V, 200s.
[0063] 3) The sample was detected using differential pulse voltammetry with the following parameters: the scanning range was -1 to -0.4V; the amplitude, pulse width, sampling width, pulse period, and equilibration time were 50mV, 0.05s, 0.0167, 0.1s, and 10s, respectively.
[0064] The results obtained in Example 3 are as follows Figure 2 As shown, Figure 2 An electrochemical sensor constructed with Ta-BTDC-COF was used to detect the DPV response of different concentrations of Pb(II). Ta-BTDC-COF was modified onto the surface of the working electrode in a screen-printed electrode, and the scanning range was -1.0 to -0.4 V.
[0065] Figure 2 The sample preparation method was as follows: a 1000 mg / L Pb(II) standard solution was added to ultrapure water, and the concentrations of each sample were 0.5 μg / L, 1 μg / L, 2.5 μg / L, 5 μg / L, 10 μg / L, 25 μg / L, 50 μg / L, 0.1 mg / L, 0.25 mg / L, 0.5 mg / L, and 1 mg / L.
[0066] from Figure 2The DPV curves shown indicate that the detection limit for lead is 0.5 μg / L, and the detection range for lead content is 0.5 μg / L to 1 mg / L, specifically 0.5 μg / L, 1 μg / L, 2.5 μg / L, 5 μg / L, 10 μg / L, 25 μg / L, 50 μg / L, 0.1 mg / L, 0.25 mg / L, 0.5 mg / L, and 1 mg / L.
[0067] As the concentration of Pb(II) increases, the DPV response gradually increases. As shown in the figure, the electrochemical sensor exhibits an extremely low detection limit and a wide linear range for Pb(II).
[0068] Example 4 uses the sensor from Example 2 to detect arsenic-containing samples.
[0069] The difference between the detection method and Example 3 is that when detecting the As(V) content of the sample, it is not necessary to use the constant potential it curve for enrichment, but only the differential pulse voltammetry is performed. The scanning range of the differential pulse voltammetry is -0.4 to 0.4V.
[0070] The results obtained in Example 4 are as follows Figure 3 As shown, Figure 3 The electrochemical sensor constructed using Ta-BTDC-COF detected the DPV response of different concentrations of As (V). As shown in the figure, the scanning range of this electrochemical sensor is -0.8 to 0.8 V. The arsenic-containing water sample used was processed according to the method in Example 3, and the concentration of the arsenic standard solution used was 1000 mg / L.
[0071] from Figure 3 The DPV curves shown indicate that the detection limit for arsenic is 25 μg / L, and the detection range for arsenic content is 25 μg / L to 10 mg / L, specifically 25 μg / L, 50 μg / L, 0.1 mg / L, 0.25 mg / L, 0.5 mg / L, 1 mg / L, 3 mg / L, 5 mg / L, and 10 mg / L.
[0072] As the concentration of As(V) increases, the DPV response gradually increases. As shown in the figure, the electrochemical sensor exhibits a low detection limit, wide linearity, and satisfactory dynamic range for As(V).
[0073] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A one-dimensional linear imine-based covalent organic framework Ta-BTDC-COF material, characterized in that, When magnified to 500 nm, the morphology is a hollow tubular cluster; Used to detect lead and arsenic ions in water samples after being made into an electrochemical sensor; One-dimensional linear imine covalent organic framework Ta-BTDC-COF material is prepared by the following steps: 4,4-diaminoterphenyl and [2,2'-dithiophene]-5,5'-dicarboxaldehyde are dissolved in a mixed solvent to obtain a mixed reaction solution; Add 1 mL of 9 mol / L acetic acid aqueous solution to the mixed reaction solution, sonicate for 10 min, and react at 120℃ for 72 h to obtain the product containing a one-dimensional linear imine covalent organic framework Ta-BTDC-COF material; The mixed solvent used was trimethylbenzene:1,4-dioxane in a volume ratio of 1:
1.
2. The one-dimensional linear imine covalent organic framework Ta-BTDC-COF material according to claim 1, characterized in that, The detection limit for arsenic is 25 μg / L; the detection limit for lead is 0.5 μg / L.
3. The one-dimensional linear imine covalent organic framework Ta-BTDC-COF material according to claim 1, characterized in that, The process also includes washing and drying the resulting product with acetone to obtain a one-dimensional linear imine covalent organic framework Ta-BTDC-COF material.
4. The one-dimensional linear imine covalent organic framework Ta-BTDC-COF material according to claim 3, characterized in that, The acetone cleaning was performed three times.
5. The one-dimensional linear imine covalent organic framework Ta-BTDC-COF material according to claim 3, characterized in that, The drying conditions were 60℃ for 12 hours.
6. An electrochemical sensor, characterized in that, include: The substrate electrode is modified with the one-dimensional linear imine covalent organic framework Ta-BTDC-COF material as described in any one of claims 1 to 5. When the resulting electrochemical sensor is used for water sample detection, the detection limit for arsenic is 25 μg / L and the detection limit for lead is 0.5 μg / L.
7. The electrochemical sensor according to claim 6, characterized in that, The substrate electrode is a screen-printed electrode.
8. The electrochemical sensor according to claim 6, characterized in that, The modification method includes the following steps: dispersing the powdered one-dimensional linear imine covalent organic framework Ta-BTDC-COF material in water and sonicating it to obtain a suspension; The suspension was dropped onto the substrate electrode and dried by infrared irradiation to obtain a substrate electrode modified with a one-dimensional linear imine covalent organic framework material Ta-BTDC-COF.
9. A detection method for an electrochemical sensor as described in any one of claims 6 to 8, characterized in that, Includes the following steps: The sample solution to be tested was dropped onto the substrate electrode and detected using differential pulse voltammetry to obtain the results.
10. The detection method for an electrochemical sensor according to claim 9, characterized in that, When detecting lead content in a sample, heavy metal ions are enriched using a constant potential (it) curve before differential pulse voltammetry detection.
11. The detection method for an electrochemical sensor according to claim 9, characterized in that, The parameters for the potential-it curve detection are: 1.5V, 200s.
12. The detection method for an electrochemical sensor according to claim 9, characterized in that, When detecting lead content in a sample, the parameters for differential pulse voltammetry are: scan range of -1 to -0.4V; amplitude, pulse width, sampling width, pulse period, and equilibration time of 50mV, 0.05s, 0.0167, 0.1s, and 10s, respectively.
13. The detection method for an electrochemical sensor according to claim 9, characterized in that, When detecting arsenic content in a sample, the parameters for differential pulse voltammetry are: scan range of -0.4 to 0.4 V; amplitude, pulse width, sampling width, pulse period, and equilibration time of 50 mV, 0.05 s, 0.0167, 0.1 s, and 10 s, respectively.