Polyaniline composite bismuth film glassy carbon electrode and preparation method and application thereof

Abstract

The invention discloses a polyaniline composite bismuth film glassy carbon electrode and a preparation method and application thereof. The preparation method comprises the following steps: generating an amino polyacid doped one-dimensional polyaniline material PANI / GCE on the surface of a glassy carbon electrode in situ, and then further reducing bismuth nitrate on the surface of the glassy carbon electrode in situ in an alcoholic solution to obtain the polyaniline composite bismuth film glassy carbon electrode Bi / PANI / GCE. The response performance of the electrode to heavy metal ions can be greatly improved, good detection sensitivity and electrode stability are shown to trace heavy metal ions such as Cr (VI) and Cu (II), and rapid detection of trace heavy metal ions in liquid is achieved. The bismuth film preparation process is simple, and compared with a bismuth film pre-plating method and an in-situ bismuth plating method for preparing the bismuth film, the method for in-situ reduction of bismuth nitrate in the alcohol solution can effectively avoid the use of an acidic low-pH electrolyte solution, reduce the erosion of an electrode material and prolong the service life of an electrode.

Description

Technical Field

[0001] The present invention relates to the field of heavy metal ion detection, and particularly to a polyaniline composite bismuth film glassy carbon electrode, a preparation method thereof, and an application thereof. Background Art

[0002] Different from organic pollutants, heavy metals have stable chemical properties and are difficult to be gradually degraded in the natural environment. Therefore, heavy metal ions will continuously accumulate in soil and water bodies and finally enter the human body through the food chain, endangering human health. Therefore, in order to achieve strict control of heavy metal pollution and effectively evaluate its ecological environment behavior, there is an urgent need to develop simple, rapid, and highly sensitive on-site detection and analysis methods.

[0003] Currently, the detection methods for heavy metal ions mainly include atomic absorption spectrometry, atomic fluorescence spectrometry, ultraviolet-visible spectrophotometry, high-performance liquid chromatography, inductively coupled plasma mass spectrometry, and electrochemical methods, etc. However, these detection methods not only require expensive instruments and have high costs, but also have complex detection methods, long detection cycles, and poor detection accuracy and repeatability. In contrast, electrochemical analysis methods have high sensitivity, simple operation, low cost, and are easy to miniaturize and automate instruments, and have broad development prospects in the field of heavy metal detection.

[0004] The core of constructing an electrochemical sensor lies in the design of the surface layer of the working electrode, which is mainly reflected in the selection of modification materials and modification methods. After the surface of the working electrode is appropriately modified, the electrode sensitivity can be significantly improved, the detection limit can be reduced, and the detection ability and detection effect can be improved. Commonly used electrode modification materials mainly include metal oxides, conductive polymers, nanomaterials, carbon nanomaterials, and metal thin films, etc. Among them, the preparation of bismuth film electrode materials that replace toxic mercury film electrodes is an important direction in modern electroanalysis research. Compared with using bismuth film alone, introducing a conductive material on the surface of the working electrode to prepare a composite electrode can significantly enhance the current response and improve the detection effect of the bismuth film. Currently, researchers generally use the drop-coating method to perform composite modification on bismuth film electrodes. However, the working electrode materials prepared by this method are relatively easy to fall off, which will greatly reduce the service life of the sensing electrode. Summary of the Invention

[0005] In view of this, the present invention provides a polyaniline composite bismuth film glassy carbon electrode, a preparation method thereof, and an application thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A preparation method of a polyaniline composite bismuth film glassy carbon electrode, in which a one-dimensional polyaniline material PANI / GCE doped with amino polyacid is in-situ generated on the surface of a glassy carbon electrode, and then bismuth nitrate is further in-situ reduced on its surface in an alcohol solution to obtain a polyaniline composite bismuth film glassy carbon electrode Bi / PANI / GCE.

[0008] Preferably, the specific steps of the above preparation method of a polyaniline composite bismuth film glassy carbon electrode are as follows:

[0009] (1) Preparation of the PANI / GCE electrode: Dissolve amino polycarboxylic acid in water, and sequentially add perchloric acid and aniline monomer under cold bath stirring conditions. Then, put the activated glassy carbon electrode into this solution to soak, and then add an aqueous solution containing perchloric acid and ammonium persulfate. Continue to stir and react for a certain time under cold bath conditions. After the reaction is completed, take out the electrode and rinse it clean with ultrapure water to obtain the PANI / GCE electrode;

[0010] (2) Preparation of the Bi / PANI / GCE electrode: Ultrasonically disperse bismuth nitrate pentahydrate in an organic solvent, then put the PANI / GCE electrode into this solution to soak, and then, under cold bath stirring conditions, add an ice-bath aqueous solution containing sodium borohydride to this solution. After the reaction, quickly take out the electrode and rinse it clean with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0011] Preferably, the amino polyacid includes any one or more of diethylenetriaminepentaacetic acid DTPA, N-β-hydroxyethylenediaminetriacetic acid HEDTA, ethylenediaminetetraacetic acid EDTA, tartaric acid, citric acid, and malic acid.

[0012] Preferably, in step (1), the concentration of amino polycarboxylic acid in water is 0.8 - 2 mol / L; the concentration of perchloric acid is 0.5 - 2 mol / L, the molar ratio of amino polyacid to aniline monomer is 1:10 - 1:50, and the molar ratio of ammonium persulfate to aniline monomer is 1:3 - 3:1.

[0013] The beneficial effects of adopting the above technical scheme: If the concentration of perchloric acid is too low or too high, it will limit the growth of polyaniline chains, reduce the yield of polyaniline and be unfavorable for the formation of one-dimensional polyaniline; the molar ratio of ammonium persulfate to aniline monomer has a certain influence on the morphology of polyaniline. When the molar ratio of ammonium persulfate to aniline monomer is less than 1:3 or greater than 3:1, in addition to one-dimensional polyaniline, a large amount of polyaniline particles will be generated, and the benzoquinone structure of polyaniline will be damaged, which is unfavorable for the further doping of polyacid; when the molar ratio of polyacid to aniline is too low, the content of doped acid will be reduced, which is unfavorable for the coordination adsorption of heavy metal ions by the electrode. If the molar ratio of polyacid to aniline is too high, it may lead to a decrease in the conductivity of polyaniline, changes in thermal stability, and changes in microstructure and morphology.

[0014] Preferably, in step (1), the cold bath temperature is 0 - 5°C, the soaking time of the well-activated glass electrode is 5 - 10 min, and the reaction time is 24 - 48 h.

[0015] Preferably, in step (2), the organic solvent is one or more of ethylene glycol, diethylene glycol, triethylene glycol, and glycerol. After bismuth nitrate pentahydrate is dispersed into the organic solvent, the concentration is 6 - 15 g / L, and the concentration of the ice-bath aqueous solution dissolved with sodium borohydride is 6 - 10 g / L.

[0016] The beneficial effects of adopting the above technical solution: The bismuth film content and thickness of the bismuth film electrode will affect the performance of the electrode, such as the detection sensitivity, detection limit, and stability of the electrode. And the present invention can adjust the bismuth film content and thickness in the final electrode by changing the concentration of bismuth nitrate added during the reaction process.

[0017] Preferably, in step (2), the cold bath temperature is 5°C, the soaking time is 5 min, and the reaction time is 10 s.

[0018] The present invention also discloses the application of the polyaniline composite bismuth film glassy carbon electrode prepared by the above preparation method in the detection of heavy metal ions.

[0019] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a preparation method of a polyaniline composite bismuth film glassy carbon electrode for the detection of heavy metal ions. The one-dimensional PANI nanostructure exhibits better optoelectronic / electrochemical properties than the PANI with random particles, and the nanoarray is also more conducive to the transmission of ions and electrons. At the same time, based on the synergistic effect of bismuth nanoparticles and the good coordination effect between polyoxometalates and heavy metal ions, the response performance of the electrode to heavy metal ions can be greatly improved. Compared with the bare GCE electrode and the PANI / GCE electrode, the Bi / PANI / GCE electrode can effectively improve the signal response of the working electrode, reduce the solution resistance, and show good detection sensitivity and electrode stability for trace heavy metal ions such as Cr(VI) and Cu(II), realizing the rapid detection of trace heavy metal ions in liquids. The bismuth film preparation process of the present invention is simple. Compared with the methods of preparing bismuth films by pre-plating bismuth films and in-situ plating bismuth films, the method of in-situ reducing bismuth nitrate in an alcohol solution can effectively avoid the use of acidic low-pH electrolyte solutions, reduce the erosion of electrode materials, and improve the service life of the electrode. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the polyaniline composite bismuth film glassy carbon electrode prepared by the present invention.

[0021] Figure 2SEM images of the electrodes prepared in Example 1 of the present invention. Among them, (a) is the SEM image of the PANI / GCE electrode, and (b) is the SEM image of the Bi / PANI / GCE electrode.

[0022] Figure 3 Infrared spectra of the PANI / GCE electrodes prepared in Example 1 and Example 2 of the present invention.

[0023] Figure 4 For the bare GCE electrode, the PANI / GCE electrode and the Bi / PANI / GCE electrode prepared in Example 1 of the present invention in [Fe(CN) 6 3- / 4- Performance test diagrams, where (a) is the CV diagram; (b) is the LSV curve; (c) is the EIS diagram.

[0024] Figure 5 DPV response diagram (a) and linear fitting curve (b) of the Bi / PANI / GCE electrode prepared in Example 1 of the present invention for different concentrations of Cr(Ⅵ). [Using the lowest detection limit formula: LOD = 3*s / k (s represents the standard deviation of parallel determination of n blank samples, and k represents the slope of the standard curve), the lowest detection concentration of Cr(Ⅵ) is calculated to be 1.10 μg / L.]

[0025] Figure 6 Trend diagram of the stripping peak current change of the Bi / PANI / GCE electrode prepared in Example 1 of the present invention for the 10 μg / L Cr(VI) solution, measured once a day for 10 consecutive days. It is found that the stripping peak current of the electrode only decreases by 2.46%, indicating that the modified electrode has good stability.

[0026] Figure 7 Comparison of the DPV response diagrams of the Bi / PANI / GCE electrodes prepared in Example 1 and Example 6 of the present invention for the same concentration of Cr(Ⅵ).

[0027] Figure 8 DPV response diagram and linear fitting curve of the Bi / PANI / GCE electrode prepared in Example 4 of the present invention for different concentrations of Cu(II). [Using the lowest detection limit formula: LOD = 3*s / k (s represents the standard deviation of parallel determination of n blank samples, and k represents the slope of the standard curve), the lowest detection concentration of Cu(II) is calculated to be 3.12 μg / L.] Detailed implementation manners

[0028] The following describes the embodiments of the present invention. The examples of the embodiments are shown in the drawings. The embodiments described with reference to the drawings are exemplary and are intended to explain the present invention, rather than being construed as a limitation of the present invention.

[0029] Example 1​

[0030] Dissolve 0.04 mmol of diethylenetriaminepentaacetic anhydride in 37 mL of water. After cooling to 5 °C in a cold bath, successively add 3.26 mL of perchloric acid and 37 μL of aniline under magnetic stirring conditions. Continue stirring for 30 min, then immerse the activated glassy carbon electrode in this solution for 5 min. Then add an aqueous solution of 9.2 mL containing 0.82 mL of perchloric acid and 60.9 mg of ammonium persulfate that has been cooled to 5 °C in a cold bath, and continue stirring and reacting at 5 °C for 24 hours. After the reaction is completed, take out the electrode and rinse it thoroughly with ultrapure water to obtain the PANI / GCE electrode.

[0031] Ultrasonically disperse 72.8 mg of bismuth nitrate pentahydrate in 5 mL of ethylene glycol, then immerse the above-prepared PANI / GCE electrode in this solution for 5 min. Then, under the conditions of cold bath stirring at 5 °C, add 5 mL of an ice-bath aqueous solution containing 50 mg of sodium borohydride to this solution. After reacting for 10 s, quickly take out the electrode and slowly rinse it thoroughly with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0032] From Figure 2 the SEM images of the PANI / GCE electrode and the Bi / PANI / GCE electrode, it can be easily seen that the PNAI in-situ grown on the GCE is a one-dimensional nanoarray structure. After in-situ reducing bismuth nitrate on its surface, the polyaniline array on the surface of the Bi / PANI / GCE electrode is covered by a large number of stacked bismuth particles. Figure 4 (a) shows the comparison of the CV curves of the three electrodes of GCE, PANI / GCE, and Bi / PANI / GCE in 6 3- / 4- . The results show that the PANI / GCE electrode and the Bi / PANI / GCE electrode exhibit redox curves with better symmetry compared to the bare GCE electrode, indicating that these two electrodes have good reversibility. From the current values, the Bi / PANI / GCE electrode is significantly larger than the other two electrodes, indicating that after the electrode is modified with a bismuth film, the signal response of the working electrode can be effectively improved, thereby enhancing the detection sensitivity of the sensing electrode. During the scanning process from -0.1 V to 0.6 V, the LSV curves of the three electrodes Figure 4 (b) all show a reduction peak near 0.3 V, and the order of the peak currents is Bi / PANI / GCE electrode > PANI / GCE electrode > GCE electrode. Its EIS curve Figure 4 (c) shows that the impedances of the PANI / GCE electrode and the Bi / PANI / GCE electrode are similar and significantly smaller than that of the GCE electrode. The above results indicate that PNAI can effectively improve the conductivity of the glassy carbon electrode, increase the charge transfer efficiency, and is beneficial to improving the electrochemical detection activity, while the combination of PANI and the Bi film can achieve more excellent results.​

[0033] Example 2

[0034] Dissolve 0.08 mmol of L-tartaric acid in 37 mL of water. After cooling to 5 °C in a cold bath, sequentially add 3.26 mL of perchloric acid and 37 μL of aniline under magnetic stirring conditions. Continue stirring for 30 min, then immerse the activated glassy carbon electrode in this solution for 5 min. Then add 9.2 mL of an aqueous solution containing 0.82 mL of perchloric acid and 100 mg of ammonium persulfate that has been cooled to 5 °C, and continue stirring and reacting at 5 °C for 24 hours. After the reaction is completed, take out the electrode and rinse it thoroughly with ultrapure water to obtain the PANI / GCE electrode.

[0035] Ultrasonically disperse 72.8 mg of bismuth nitrate pentahydrate in 5 mL of ethylene glycol. Then immerse the above-prepared PANI / GCE electrode in this solution for 5 min. Then, under the conditions of cold bath stirring at 5 °C, add 5 mL of an ice-bath aqueous solution containing 50 mg of sodium borohydride to this solution. After reacting for 10 s, quickly take out the electrode and slowly rinse it thoroughly with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0036] It was found from Figure 3 that in the infrared spectra of PANI / GCE electrodes modified with different amino polyacids, C═C stretching vibration peaks attributed to the quinoid structure and benzenoid structure in PANI appeared at 1559 cm -1 and 1482 cm -1 . The C-N stretching vibrations corresponding to the quinoid structure and benzenoid structure in the PANI chain appeared at 1293 cm -1 and 1235 cm -1 respectively, and the asymmetric vibration peak attributed to the isocyanate group (N═C═O) appeared at 2253 cm -1 , indicating that the glassy carbon electrode was successfully modified with an amino polyacid-doped polyaniline material.

[0037] Example 3

[0038] Dissolve 0.03 mmol of N-β-hydroxyethyl ethylenediamine triacetic acid (HEDTA) in 37 mL of water. After cooling to 5 °C in a cold bath, sequentially add 3.26 mL of perchloric acid and 37 μL of aniline under magnetic stirring conditions. Continue stirring for 30 min, then immerse the activated glassy carbon electrode in this solution for 5 min. Then add 9.2 mL of an aqueous solution containing 0.82 mL of perchloric acid and 60.9 mg of ammonium persulfate that has been cooled to 5 °C, and continue stirring and reacting at 5 °C for 24 hours. After the reaction is completed, take out the electrode and rinse it thoroughly with ultrapure water to obtain the PANI / GCE electrode.

[0039] 72.8 mg of bismuth nitrate pentahydrate was ultrasonically dispersed in 5 mL of ethylene glycol. Then, the prepared PANI / GCE electrode was immersed in this solution for 5 min. Next, under the conditions of stirring in a 5 °C cold bath, 5 mL of an ice-bath aqueous solution containing 50 mg of sodium borohydride was added to this solution. After reacting for 10 s, the electrode was quickly taken out and slowly rinsed clean with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0040] Example 4

[0041] 0.03 mmol of EDTA was dissolved in 37 mL of water. After cooling to 5 °C in a cold bath and under magnetic stirring conditions, 3.26 mL of perchloric acid and 37 μL of aniline were added successively. Stirring was continued for 30 min. Then, the activated glassy carbon electrode was immersed in this solution for 5 min. Next, 9.2 mL of an aqueous solution containing 0.82 mL of perchloric acid and 80 mg of ammonium persulfate, which had been cooled to 5 °C in a cold bath, was added, and stirring was continued for 24 h at 5 °C. After the reaction ended, the electrode was taken out and rinsed clean with ultrapure water to obtain the PANI / GCE electrode.

[0042] 72.8 mg of bismuth nitrate pentahydrate was ultrasonically dispersed in 5 mL of ethylene glycol. Then, the prepared PANI / GCE electrode was immersed in this solution for 5 min. Next, under the conditions of stirring in a 5 °C cold bath, 5 mL of an ice-bath aqueous solution containing 50 mg of sodium borohydride was added to this solution. After reacting for 10 s, the electrode was quickly taken out and slowly rinsed clean with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0043] Example 5

[0044] 0.04 mmol of diethylenetriaminepentaacetic dianhydride was dissolved in 37 mL of water. After cooling to 5 °C in a cold bath and under magnetic stirring conditions, 3.26 mL of perchloric acid and 37 μL of aniline were added successively. Stirring was continued for 30 min. Then, the activated glassy carbon electrode was immersed in this solution for 5 min. Next, 9.2 mL of an aqueous solution containing 0.82 mL of perchloric acid and 60.9 mg of ammonium persulfate, which had been cooled to 5 °C in a cold bath, was added, and stirring was continued for 24 h at 5 °C. After the reaction ended, the electrode was taken out and rinsed clean with ultrapure water to obtain the PANI / GCE electrode.

[0045] 30 mg of bismuth nitrate pentahydrate was ultrasonically dispersed in 5 mL of ethylene glycol. Then, the prepared PANI / GCE electrode was immersed in this solution for 5 min. Next, under the conditions of stirring in a 5 °C cold bath, 5 mL of an ice-bath aqueous solution containing 30 mg of sodium borohydride was added to this solution. After reacting for 10 s, the electrode was quickly taken out and slowly rinsed clean with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0046] Example 6

[0047] Dissolve 0.04 mmol of diethylenetriaminepentaacetic dianhydride in 37 mL of water. After cooling the bath to 5 °C, sequentially add 3.26 mL of perchloric acid and 37 μL of aniline under magnetic stirring conditions. Continue stirring for 30 min, then immerse the activated glassy carbon electrode in this solution for 5 min. Next, add 9.2 mL of an aqueous solution containing 0.82 mL of perchloric acid and 60.9 mg of ammonium persulfate that has been cooled to 5 °C in a cold bath, and continue stirring and reacting at a low temperature of 5 °C for 24 hours. After the reaction is completed, take out the electrode and rinse it thoroughly with ultrapure water to obtain the PANI / GCE electrode.

[0048] Ultrasonically disperse 72.8 mg of bismuth nitrate pentahydrate in 5 mL of diglycol. Then immerse the above-prepared PANI / GCE electrode in this solution for 5 min. Next, under the conditions of cold bath stirring at 5 °C, add 5 mL of an ice-bath aqueous solution containing 50 mg of sodium borohydride to this solution. After reacting for 10 s, quickly take out the electrode and slowly rinse it thoroughly with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0049] From Figure 7 The comparative DPV response diagram of the Bi / PANI / GCE electrodes prepared in Example 6 and Example 1 as shown indicates that the role of the organic solvent in Step 2 is to dissolve bismuth nitrate, and the choice of its solvent has little effect on the detection performance of the electrode.

[0050] Example 7

[0051] Dissolve 0.04 mmol of diethylenetriaminepentaacetic dianhydride in 37 mL of water. After cooling the bath to 5 °C, sequentially add 3.26 mL of perchloric acid and 37 μL of aniline under magnetic stirring conditions. Continue stirring for 30 min, then immerse the activated glassy carbon electrode in this solution for 5 min. Next, add 9.2 mL of an aqueous solution containing 0.82 mL of perchloric acid and 60.9 mg of ammonium persulfate that has been cooled to 5 °C in a cold bath, and continue stirring and reacting at a low temperature of 5 °C for 24 hours. After the reaction is completed, take out the electrode and rinse it thoroughly with ultrapure water to obtain the PANI / GCE electrode.

[0052] Ultrasonically disperse 145.6 mg of bismuth nitrate pentahydrate in 5 mL of ethylene glycol. Then immerse the above-prepared PANI / GCE electrode in this solution for 5 min. Next, under the conditions of cold bath stirring at 5 °C, add 5 mL of an ice-bath aqueous solution containing 50 mg of sodium borohydride to this solution. After reacting for 10 s, quickly take out the electrode and slowly rinse it thoroughly with ultrapure water to obtain the Bi / PANI / GCE electrode.

[0053] The bismuth film content and thickness of the bismuth film electrode will affect the performance of the electrode. The bismuth film content and thickness in Examples 1, 5 and 7 are shown in Table 1, and the results show that the present invention can adjust the bismuth film content and thickness in the final electrode by changing the concentration of bismuth nitrate added during the reaction process.

[0054] Table 1. Bismuth film content and thickness with different bismuth nitrate input amounts

[0055]

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a polyaniline composite bismuth film glassy carbon electrode, characterized in that: An amino acid-doped one-dimensional polyaniline material PANI / GCE is in situ generated on the surface of a glassy carbon electrode, and then bismuth nitrate is further in situ reduced on its surface in an alcohol solution to obtain a polyaniline composite bismuth film glassy carbon electrode Bi / PANI / GCE.

2. The method for preparing a polyaniline composite bismuth film glassy carbon electrode according to claim 1, characterized in that: The specific steps are as follows: (1) Preparation of PANI / GCE electrode: aminopolycarboxylic acid is dissolved in water, and perchloric acid and aniline monomer are added in sequence under cold bath stirring conditions, and then the activated glassy carbon electrode is immersed in the solution, and then an aqueous solution containing perchloric acid and ammonium persulfate is added, and the reaction is continued under cold bath stirring for a certain period of time. After the reaction is completed, the electrode is taken out and rinsed with ultrapure water to obtain a PANI / GCE electrode; (2) Preparation of Bi / PANI / GCE electrode: Bismuth nitrate pentahydrate is ultrasonically dispersed in an organic solvent, and then a PANI / GCE electrode is immersed in the solution. Then, an ice bath aqueous solution containing sodium borohydride is added to the solution under cold bath stirring. After the reaction, the electrode is quickly taken out and rinsed with ultrapure water to obtain a Bi / PANI / GCE electrode.

3. The method for preparing a polyaniline composite bismuth film glassy carbon electrode according to claim 1, characterized in that: The amino polyacid includes any one or more of diethylenetriaminepentaacetic acid DTPA, N-β-hydroxyethylethylenediaminetriacetic acid HEDTA, ethylenediaminetetraacetic acid EDTA, tartaric acid, citric acid, and malic acid.

4. The method for preparing a polyaniline composite bismuth film glassy carbon electrode according to claim 2, characterized in that: In step (1), the concentration of aminopolycarboxylic acid after being dissolved in water is 0.8-2 mol / L; the concentration of perchloric acid is 0.5-2 mol / L, the molar ratio of aminopolyacid to aniline monomer is 1:10-1:50, and the molar ratio of ammonium persulfate to aniline monomer is 1:3-3:

1.

5. The method for preparing a polyaniline composite bismuth film glassy carbon electrode according to claim 2, characterized in that: In step (1), the cold bath temperature is 0-5°C, the activated glass electrode is immersed for 5-10 minutes, and the reaction time is 24-48 hours.

6. The method for preparing a polyaniline composite bismuth film glassy carbon electrode according to claim 2, characterized in that: In step (2), the organic solvent is any one or more of ethylene glycol, diethylene glycol, triethylene glycol, and glycerol; the concentration of bismuth nitrate pentahydrate after being dispersed in the organic solvent is 6-15 g / L; and the concentration of the ice bath aqueous solution in which sodium borohydride is dissolved is 6-10 g / L.

7. The method for preparing a polyaniline composite bismuth film glassy carbon electrode according to claim 2, characterized in that: In step (2), the cold bath temperature is 5° C., the immersion time is 5 min, and the reaction time is 10 s.

8. A polyaniline composite bismuth film glassy carbon electrode prepared according to the preparation method described in any one of claims 1 to 7.

9. Use of the polyaniline composite bismuth film glassy carbon electrode as claimed in claim 8 in the detection of heavy metal ions.

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