CN115096971A - Glassy carbon electrode for detecting mercury ions and preparation method and application thereof - Google Patents
Glassy carbon electrode for detecting mercury ions and preparation method and application thereof Download PDFInfo
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- G—PHYSICS
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- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
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- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
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- G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
Abstract
The invention relates to the technical field of electrochemical analysis and detection, and particularly discloses a preparation method of a glassy carbon electrode for detecting mercury ions, which comprises the following steps: pretreating the glassy carbon electrode; preparing nano zinc oxide and carboxylated carbon nanotube modified solution, and dripping the modified solution on the surface of the glassy carbon electrode to obtain a nano zinc oxide/carbon nanotube composite glassy carbon electrode; and (3) placing the nano zinc oxide/carbon nano tube composite glassy carbon electrode in a chloroauric acid solution for electrodeposition to obtain the nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode. According to the preparation method of the glassy carbon electrode for detecting mercury ions, the carbon nano tube-nano zinc oxide is used as an effective substrate to fix the gold nano particles, the stability of the electrode and the electron transfer capability are enhanced, the detection limit can reach 0.0156 mu M, the linear range is 1.49-5.97 mu M, and the rapid and sensitive detection of trace mercury ions in seawater is effectively realized; the preparation process is simple, the detection method is sensitive, and the detection equipment is portable.
Description
Technical Field
The invention belongs to the technical field of electrochemical analysis and detection, and particularly relates to a glassy carbon electrode for detecting mercury ions as well as a preparation method and application thereof.
Background
Mercury is a natural pollutant, exists in air, soil and water, and is extremely easy to be polluted by mercury ions due to sea-land interaction, and the pollution mainly comprises industrial chemical activities, treatment of waste electronic batteries, domestic sewage and the like. Mercury, one of the most toxic heavy metal ions, is more likely to cause fatal damage to organisms even at a trace level because it prefers to bind to the thiol group of proteins, resulting in cytotoxicity, endangering the central nervous system, digestive system and kidney, and the World Health Organization (WHO) stipulates that the maximum content of mercury in seawater is 30nM, and thus, the detection of trace mercury ions in the near coast is of great practical significance.
The electrochemical method has attracted extensive attention because of its advantages such as simple instrument operation, high sensitivity and quick response, among which, the Differential Pulse Voltammetry (DPV) is a main detection and analysis method which can convert some chemical parameters difficult to be measured into electrical parameters easy to be measured and can measure the change of trace substances by weak current signals, thus realizing high-precision and sensitive detection.
Differential Pulse Voltammetry (DPV) is based on a three-electrode system, wherein a working electrode is a glassy carbon electrode, and mercury ions can not be detected by directly utilizing the glassy carbon electrode because of too low data, so that the Differential Pulse Voltammetry (DPV) has low sensitivity and is difficult to detect trace mercury ions. The method develops a glassy carbon electrode which can detect trace mercury ions and has high sensitivity, researches on modifying a layer of material with a specific function on the surface of the existing electrode to enable the electrode to obtain required special performance and enable the reaction to be rapidly and efficiently carried out, thereby detecting the trace mercury ions and having important significance for the detection of the trace mercury ions in the near coast and the protection of water bodies.
Disclosure of Invention
The invention aims to provide a glassy carbon electrode for detecting mercury ions and a preparation method thereof.
In order to achieve the above purpose, the invention provides a preparation method of a glassy carbon electrode for detecting mercury ions, which comprises the following steps:
(1) pretreating the glassy carbon electrode;
(2) preparing a nano zinc oxide and carbon nano tube modification solution, and dripping the modification solution on the surface of the glassy carbon electrode obtained in the step (1) to obtain a nano zinc oxide/carbon nano tube composite glassy carbon electrode;
(3) and (3) putting the nano zinc oxide/carbon nano tube composite glassy carbon electrode obtained in the step (2) into a chloroauric acid solution for electrodeposition to obtain a nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode, namely the glassy carbon electrode for detecting mercury ions.
According to the invention, the nano zinc oxide and the carbon nano tube are dripped on the surface of the glassy carbon electrode to be used as substrate materials, wherein the carbon nano tube has the characteristics of high conductivity, large specific surface area and the like, the nano zinc oxide has excellent performances in the aspects of magnetism, optics and electricity, the nano zinc oxide and the carbon nano tube are combined together and coated on the surface of the glassy carbon electrode, the ion adsorption of the electrode is increased, the conductivity is enhanced, and the efficiency and the effect of gold electrodeposition can be improved; and then electrodepositing chloroauric acid solution, modifying the nano zinc oxide/carbon nano tube/nano gold composite film on the glassy carbon electrode, and detecting the content of the seawater-based mercury ions based on the differential pulse voltammetry, wherein the modified nano zinc oxide/carbon nano tube/nano gold composite film can amplify response signals, improve detection sensitivity and detect trace mercury ions.
Preferably, in the above preparation method of a glassy carbon electrode for detecting mercury ions, in the step (1), the glassy carbon electrode is polished and cleaned, and the cleaned glassy carbon electrode is placed at 0.5 mol/L -1 H 2 SO 4 The middle cycle scans until stable.
Preferably, the above-mentioned is used forIn the preparation method of the glassy carbon electrode for detecting mercury ions, 1.0 mu m, 0.3 mu m and 5nm Al are used in sequence 2 O 3 Polishing the glassy carbon electrode to a mirror surface by using powder, and sequentially ultrasonically cleaning the glassy carbon electrode for 3min by using ultrapure water and absolute ethyl alcohol after the glassy carbon electrode is cleaned by washing to remove surface powder; then at 0.5 mol/l of H 2 SO 4 And (3) scanning the solution from-0.4V to +0.6V by Cyclic Voltammetry (CV) until the solution is stable, finally washing the electrode by ultrapure water, and performing a cyclic voltammetry experiment after blowing by nitrogen until a stable redox peak with a potential difference of about 90mV appears.
Preferably, in the above preparation method for detecting a mercury ion glassy carbon electrode, in the step (2), the carboxylated carbon nanotube and the nano zinc oxide are placed in dimethylformamide for ultrasonic dispersion for 30-60 min, so that a uniform black mixed solution is presented, that is, a nano zinc oxide/carbon nanotube modified solution; the solid content in the nano zinc oxide/carbon nano tube modified solution is 0.9 mg/mL.
Preferably, in the above preparation method for a glassy carbon electrode for detecting mercury ions, the mass ratio of nano zinc oxide to carbon nanotubes in the nano zinc oxide/carbon nanotube modification solution is 1: 2.
Preferably, in the above preparation method for a glassy carbon electrode for detecting mercury ions, in the step (2), the carbon nanotubes are carboxylated carbon nanotubes; by means of H 2 O 2 +HNO 3 And (3) carrying out ultrasonic treatment on the carbon nano tube in the mixed solution, filtering, washing and drying to obtain the carboxylated carbon nano tube.
Preferably, in the above preparation method for detecting mercury ion glassy carbon electrode, in the step (3), potentiostatic deposition is used, the deposition potential is-0.25 v, the deposition time is 20s, and after taking out, the glassy carbon electrode is washed with deionized water and dried, so as to obtain the nano zinc oxide/carbon nanotube/nano gold particle composite glassy carbon electrode.
The preparation method of the glassy carbon electrode for detecting mercury ions is used for preparing the nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode.
The application of the glassy carbon electrode for detecting mercury ions in the detection of mercury ions is disclosed.
Preferably, in the above application, the mercury ions are detected by using differential pulse voltammetry, the pulse range is-0.1 to 0.4V, the amplitude is 50 mV, and the three electrode systems are as follows: the nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum wire electrode is used as an auxiliary electrode.
Preferably, in the above application, the specific steps of detecting mercury ions include:
s1, preparing standard mercury ion solutions with different concentrations by using HAc-NaAc buffer solutions; immersing the three-electrode system into a standard mercury ion solution;
s2, detecting and recording response currents Ip of mercury ions with different concentrations by adopting a differential pulse voltammetry, analyzing the relation between Ip and the concentration of the mercury ions, and establishing a standard curve;
and S3, placing the three electrodes in a sample to be detected for reaction, performing differential pulse voltammetry scanning according to the method with the same steps as the electrochemical detection method, recording response current Ip, and combining a standard curve to obtain the content of mercury ions in the sample to be detected.
Preferably, in the above application, the concentration of HAc-NaAc in the standard mercury ion solution is 0.1M, and the pH of the standard mercury ion solution is 4.
Preferably, in the above application, the relationship between Ip and the mercury ion concentration satisfies the following linear relationship: i = -3.5552+5.754c, where I is response current in μ a; c represents concentration value of mercury ion in unit of μ M, R 2 Is 0.97443.
Preferably, in the above application, the sample to be detected is a seawater sample, and the seawater sample is filtered by a microporous filter membrane and subjected to ultraviolet pretreatment before detection.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the preparation method of the glassy carbon electrode for detecting mercury ions, the carbon nano tube-nano zinc oxide is used as an effective substrate to fix the gold nano particles, so that the stability and the electron transfer capability of the electrode are enhanced, a new detection means is provided for detecting mercury ions, and the rapid and sensitive detection of trace mercury ions in seawater can be realized. The preparation process for detecting the mercury ion glassy carbon electrode is simple, the prepared mercury ion glassy carbon electrode for detecting mercury ions has the characteristics of sensitivity, portability of detection equipment and the like, the detection limit can reach 0.0156 mu M, the linear range is 1.49-5.97 mu M, and the actual requirement is met.
2. According to the glassy carbon electrode for detecting mercury ions, zinc oxide and carbon nano tubes are used as substrates for detecting mercury ions, so that the adsorption of nano gold particles can be increased, the problem of poor deposition and adsorption effects of single deposited gold is solved, the activity can be effectively increased, the catalysis efficiency is high, mercury ions can be efficiently detected, the detection accuracy and sensitivity are improved, the gold nano particles are prevented from being in direct contact with the surface of the glassy carbon electrode, charge transfer and contact potential can be generated due to the difference between gold and the glassy carbon electrode, and the accuracy and sensitivity of mercury ion detection data based on a three-electrode system can be influenced.
Drawings
Fig. 1 is a flow chart of the preparation and working process of the glassy carbon electrode for detecting mercury ions.
FIG. 2 is a scanning electron microscope image of the carboxylated carbon nanotube after being treated in example 1 of the present invention.
Fig. 3 is a scanning electron microscope image of the nano zinc oxide/carbon nanotube treated in example 1 of the present invention.
Fig. 4 is a CV characterization diagram of the process of modifying nano zinc oxide/carbon nanotube/gold nanoparticle in example 1 of the present invention.
Fig. 5 is a graph showing the dissolution curves of mercury ions detected by different modified glassy carbon electrodes in application example 1 of the present invention.
Fig. 6 is a standard curve of response current and mercury ion concentration in application example 2 of the present invention.
Fig. 7 is a selective detection diagram for detecting mercury ions based on a nano zinc oxide/carbon nanotube/nano gold particle composite glassy carbon electrode in application example 2 of the present invention.
Fig. 8 is a reproducibility and stability detection diagram for detecting mercury ions based on the nano zinc oxide/carbon nanotube/nano gold particle composite glassy carbon electrode in application example 2 of the present invention: (a) the detection result of 2.48 mu M mercury ion solution; (b) and (5) detection results of 1.49 mu M mercury ion solution.
Detailed Description
The following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments.
In the following examples, electrochemical measurements were performed using a modified glassy carbon electrode as a working electrode, a saturated calomel electrode as a reference electrode, and a platinum wire electrode as an auxiliary electrode, using an electrochemical workstation (CHI 830D) of Shanghai Chenghua corporation. The preparation process and the working process of the glassy carbon electrode for detecting mercury ions are shown in figure 1.
Example 1
A preparation method of a glassy carbon electrode for detecting mercury ions comprises the following steps:
(1) electrode pretreatment: bare glassy carbon electrode (GCE, diameter 3 mm) using 1.0 μm, 0.3 μm and 5nm Al in that order 2 O 3 Polishing the powder to a mirror surface, and sequentially ultrasonically cleaning the powder for 3min by using ultrapure water and absolute ethyl alcohol after the powder is washed clean so as to remove surface powder; then at 0.5 mol/l of H 2 SO 4 Scanning the solution from-1.0V to +1.0V by Cyclic Voltammetry (CV) until the solution is stable, finally washing a glassy carbon electrode by ultrapure water, drying the glassy carbon electrode by blowing nitrogen, and performing a cyclic voltammetry experiment until a stable redox peak with a potential difference of about 90mV appears;
(2) preparing a nano zinc oxide/carbon nano tube composite electrode:
carboxylating carbon nanotube in 200 ml H through chemical acidifying oxidation process 2 O 2 +HNO 3 Mixed solution (H) 2 O 2 +HNO 3 Carrying out ultrasonic treatment on 0.5 g of carboxylated carbon nanotubes in a volume ratio of 1: 3), diluting the acid-treated carbon nanotubes with 200 ml of distilled water after 3 hours of ultrasonic treatment, and filtering through filter paper with the porosity of 3 mu m; then thoroughly washing the carbon nano tube treated by the acid with distilled water until reaching a neutral pH value, and continuously drying for 3 hours at the temperature of 100 +/-0.5 ℃ to obtain a carboxylated carbon nano tube; FIG. 2 is a scanning electron micrograph of the treated carboxylated carbon nanotube with a large specific surface area for increasing surface chargeThe ion adsorption of the pole and the conductivity enhancement;
placing 6 mg of carboxylated carbon nano tube and 3 mg of nano zinc oxide in 10 ml of dimethyl formamide for ultrasonic dispersion for more than 30min to form uniform black mixed solution, thus obtaining nano zinc oxide/carbon nano tube modified solution; dripping 5 mu L of mixed solution to the surface of the glassy carbon electrode by adopting a dripping method, and drying at 45 ℃ to obtain the nano zinc oxide/carbon nano tube composite glassy carbon electrode; FIG. 3 is a scanning electron micrograph of nano zinc oxide/carbon nanotubes, wherein the carbon nanotubes are intertwined and the nano zinc oxide is dispersed therein, so as to increase the conductivity between electrons;
(3) the nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode comprises the following components in percentage by weight: immersing the prepared zinc oxide/carbon nano tube composite glassy carbon electrode into a solution containing 1.0M HNO 3 And (3) carrying out potential deposition by a potentiostatic method in a chloroauric acid solution with the concentration of 0.01g/ml of HAc-NaAc of 0.1M, wherein the deposition potential is-0.25 v, the deposition time is 20s, taking out the chloroauric acid solution, washing with deionized water, and airing to obtain the zinc oxide/carbon nanotube/nanogold particle composite glassy carbon electrode, namely the glassy carbon electrode for detecting mercury ions.
Application example 1
1.1 modified electrode characterization
In standard electrolyte (1.0M HNO) 3 +0.1M HAc-NaAc (pH4.0) + 4.47. mu.M standard solution of mercury ions), cyclic voltammetry studies were performed on different modified electrodes, the results of which are shown in FIG. 4. Curve a is a cyclic voltammetry curve of naked GCE, a pair of reversible redox peaks appears, the potential difference of the peaks is 74.5 mV, and the ratio of the redox peak currents is 1, which indicates that the electrolyte is a good electron transfer medium; curve b, after the surface of the bare electrode is modified with the nano zinc oxide/carbon nanotube, the peak current is increased because the nano zinc oxide/carbon nanotube has a large specific surface area when being used as a substrate material, and in addition, the composite material can increase the ion adsorption of the surface electrode and increase the conductivity; the curve c is the modified nano zinc oxide/carbon nano tube/nano gold particle composite membrane, the peak current is obviously increased, and the gold nano particles have good high catalytic activity and unique biological affinity, so that the electro-catalytic oxidation effect is better. Illustrating the nano zinc oxide/carbon nano tubeThe nano gold particle composite membrane has good synergistic adsorption catalysis effect on oxidation-reduction reaction.
At 1.0M HNO 3 In the standard solution of +0.1M HAc-NaAc (PH4.0) +4.47 μ M mercury ions, different modified electrodes are used for differential pulse voltammetric scanning, and the dissolution curve of mercury ions detected by different modified glassy carbon electrodes is shown in fig. 5, which shows that the corresponding current detected by the zinc oxide/carbon nanotube/gold nanoparticle composite electrode of the present invention is significantly higher than that detected by a bare glassy carbon electrode and other modified glassy carbon electrodes, indicating that the zinc oxide/carbon nanotube/gold nanoparticle composite glassy carbon electrode of the present invention has large response signal and high sensitivity when used for detecting mercury ions.
1.2 optimum conditions for Mercury ion detection
The three electrodes are respectively detected in the PBS buffer solution and the 0.1M HAc-NaAc buffer solution, as shown in FIG. 6, the result of the HAc-NaAc buffer solution is far better than that of the PBS buffer solution, which indicates that the HAc-NaAc buffer solution can well detect the content of mercury ions.
At pH 3.0, 3.5, 4, 4.0, 4.5, 5, 5.0, 5.5, 6 respectively, containing 1.0M HNO 3 When Differential Pulse Voltammetry (DPV) scanning is carried out in a +0.1MHAc-NaAc +4.47 mercury ion standard solution, the DPV peak current value of mercury ion detection is the highest under the condition of pH value of 4, which indicates that the reaction is the most complete at the moment, and pH =4 is the optimal pH condition for detecting the concentration of mercury ions.
Application example 2
The zinc oxide/carbon nanotube/nanogold particle composite glassy carbon electrode prepared in example 1 is used for detecting mercury ions in seawater, a sample to be detected is taken from Qinjiang and Maotai and mixed with seawater flowing into university of northern gulf, and the sample to be detected is filtered and subjected to ultraviolet pretreatment for detection; three electrode bodies are used as media, the three electrode bodies are: the nano zinc oxide/carbon nanotube/nano gold particle composite glassy carbon electrode prepared in example 1 was used as a working electrode, a saturated calomel electrode was used as a reference electrode, and a platinum wire electrode was used as an auxiliary electrode. Detecting and recording peak current Ip of mercury ion content with different concentrations by using Differential Pulse Voltammetry (DPV), wherein the pulse range is as follows: -0.1 to 0.4V, amplitude: 50 mV. The method comprises the following specific steps:
s1, preparing standard mercury ion solutions with different concentrations (1.49-5.97 mu M) by using an HAc-NaAc buffer solution; immersing the three-electrode system into a standard mercury ion solution;
s2, detecting by adopting a differential pulse voltammetry method, recording response currents Ip of mercury ions with different concentrations, analyzing the relation between Ip and mercury ion concentration, and establishing a standard curve;
and S3, placing the three-electrode system in a pretreated sample to be detected for reaction, performing differential pulse voltammetry scanning according to a method with the same steps as the electrochemical detection method, recording response current Ip, and combining a standard curve to obtain the content of mercury ions in the sample to be detected.
FIG. 6 is a standard curve with a linear regression equation:I=-3.5552+5.754cthe correlation coefficient is 0.97443, where I is the response current in μ A; c represents the concentration value of mercury ions in. mu.M. The standard deviation is calculated 6 times by parallel measurement on 4.47 mu M mercury ion standard solution, the detection limit is 0.0156 mu M by calculation according to 3 sigma/S, and the recovery rate is 94.2-98.4 percent and is lower than the world standard.
The selectivity is an important parameter in the practical application of the electrochemical detection of mercury ions, and K is researched under the optimal detection condition + 、Na + 、Ba 2+ 、Cd 2+ 、Pb 2+ The selectivity of mercury ions is examined, and five cations (K) are used + 、Na + 、Ba 2+ 、Cd 2+ 、Pb 2+ ) Separately added to a solution containing 0.1MHAc-NaAc + 1.49. mu.M mercury ions, and investigated for an interferent concentration of 104. mu.M (K) + 、Na + 、Ba 2+ ) And 149 μ M (Cd) 2+ 、Pb 2+ ) And comparing the current obtained by each interference with the response current of a single mercury ion (as shown in figure 7), wherein the current change rate of the mercury ions under the interference of other ions is below 5.1% except potassium ions, and no obvious interference exists under experimental conditions, which shows that the method for detecting the mercury ions by using the differential pulse voltammetry based on the nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode has stronger anti-interference performance. In the presence of other ion interference, can beAnd obtaining the content of the mercury ions according to the peak potential (0.18-0.2V) of the mercury ions and the corresponding response current.
Reproducibility and stability are important parameters for evaluating the reliability of electrochemical detection of mercury ions in practical application. By adopting the three-electrode system of the application example, 2.48 mu M mercury ion solution is detected under the optimal condition for 6 times in parallel, the detection result is shown in figure 8 (a), and the relative standard deviation RSD of the detection result is 3.007%. Under the optimal detection condition, 1.49 mu M of mercury ion solution is detected, the detection result is shown in figure 8 (b), and the RSD of the detection result is 2.886%. The results show that the modified electrode of the composite material has good stability and reproducibility.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (10)
1. A preparation method of a glassy carbon electrode for detecting mercury ions is characterized by comprising the following steps:
(1) pretreating the glassy carbon electrode;
(2) preparing a nano zinc oxide and carbon nano tube modification solution, and dripping the modification solution on the surface of the glassy carbon electrode obtained in the step (1) to obtain a nano zinc oxide/carbon nano tube composite glassy carbon electrode;
(3) and (3) putting the nano zinc oxide/carbon nano tube composite glassy carbon electrode obtained in the step (2) into a chloroauric acid solution for electrodeposition to obtain a nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode, namely the glassy carbon electrode for detecting mercury ions.
2. According to claimThe preparation method of the glassy carbon electrode for detecting mercury ions is characterized in that in the step (1), the glassy carbon electrode is polished and cleaned, and the cleaned glassy carbon electrode is arranged at 0.5 mol/L -1 H 2 SO 4 The middle cycle scans until stable.
3. The preparation method of the glassy carbon electrode for detecting mercury ions according to claim 1, wherein in the step (2), the carbon nano tubes and the nano zinc oxide are placed in dimethylformamide to be subjected to ultrasonic dispersion for 30-60 min, so that a uniform black mixed solution is presented, and the mixed solution is a nano zinc oxide/carbon nano tube modified solution; the solid content in the nano zinc oxide/carboxylated carbon nanotube modified solution is 0.9 mg/mL.
4. The preparation method of the glassy carbon electrode for detecting mercury ions according to claim 1, wherein in the step (2), the carbon nanotubes are carboxylated carbon nanotubes; by means of H 2 O 2 +HNO 3 And (3) carrying out ultrasonic treatment on the carbon nano tube in the mixed solution, filtering, washing and drying to obtain the carboxylated carbon nano tube.
5. The glassy carbon electrode for detecting mercury ions is characterized in that the glassy carbon electrode for detecting mercury ions is the nano zinc oxide/carbon nanotube/nano gold particle composite glassy carbon electrode prepared by the preparation method of the glassy carbon electrode for detecting mercury ions according to any one of claims 1 to 4.
6. The application of the glassy carbon electrode for detecting mercury ions in claim 5 in the detection of mercury ions.
7. The application of claim 6, wherein the mercury ions are detected by differential pulse voltammetry, the pulse range is-0.1-0.4V, the amplitude is 50 mV, and the three electrode systems are as follows: the nano zinc oxide/carbon nano tube/nano gold particle composite glassy carbon electrode is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum wire electrode is used as an auxiliary electrode.
8. The use according to claim 7, wherein the specific step of detecting mercury ions comprises:
s1, preparing standard mercury ion solutions with different concentrations by using an HAc-NaAc buffer solution; immersing the three-electrode system into a standard mercury ion solution;
s2, detecting by adopting a differential pulse voltammetry method, recording response currents Ip of mercury ions with different concentrations, analyzing the relation between Ip and mercury ion concentration, and establishing a standard curve;
and S3, placing the three electrodes in a sample to be detected for reaction, performing differential pulse voltammetry scanning according to the method with the same steps as the electrochemical detection method, recording response current Ip, and combining a standard curve to obtain the content of mercury ions in the sample to be detected.
9. Use according to claim 8, wherein the standard mercury ion solution has a concentration of HAc-NaAc of 0.1M and a pH of 4.
10. The application according to claim 8, wherein in the step S2, Ip and the mercury ion concentration satisfy the following linear relationship: i = -3.5552+5.754c, where I is response current in μ a; c represents concentration value of mercury ion in unit of μ M, R 2 Is 0.97443.
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