阅读说明：本技术 一种 1,8-萘二胺修饰电极的制备方法及其在银离子检测中的应用 (Preparation method of 1, 8-naphthalene diamine modified electrode and application of electrode in silver ion detection ) 是由 奚亚男 胡淑锦 于 2020-05-29 设计创作，主要内容包括：本发明提供了一种1,8-萘二胺修饰电极的制备方法及其在银离子检测中的应用。具体采用直接混合法制得1,8-萘二胺修饰电极,在0.1mol/L的硝酸溶液中进行电化学聚合,使1,8-萘二胺单体在碳糊电极本体内部形成聚合物,可实现对银离子的精准测定,并建立了微分脉冲伏安法测定银离子的检测方法。电极具有灵敏高、检出限低、抗干扰性能强等优点,电极测定银离子的线性范围为5.4-540μg/L,检出限为3.132μg/L。(The invention provides a preparation method of a 1, 8-naphthalene diamine modified electrode and application thereof in silver ion detection. Specifically, a 1, 8-naphthylenediamine modified electrode is prepared by a direct mixing method, electrochemical polymerization is carried out in a 0.1mol/L nitric acid solution, so that a 1, 8-naphthylenediamine monomer forms a polymer in a carbon paste electrode body, accurate determination of silver ions can be realized, and a detection method for determining silver ions by a differential pulse voltammetry method is established. The electrode has the advantages of high sensitivity, low detection limit, strong anti-interference performance and the like, the linear range of the electrode for measuring silver ions is 5.4-540 mu g/L, and the detection limit is 3.132 mu g/L.)

1. A preparation method of a 1, 8-naphthalene diamine modified electrode is characterized by comprising the following steps: dissolving 1, 8-naphthalenediamine monomer by using 2-3 drops of acetonitrile, adding PVC powder and a proper amount of tetrahydrofuran, adding graphite powder after the dissolution is complete, uniformly mixing after the solvent is volatilized, pressing the obtained carbon paste-shaped substance into a groove at the top end of an electrode tube, tightly filling, polishing on weighing paper, cleaning with water, placing into 0.10mol/L nitric acid solution for electropolymerization, and airing at normal temperature to obtain the modified electrode.

2. The method for preparing the 1, 8-naphthalenediamine modified electrode according to claim 1, wherein the amount of the 1, 8-naphthalenediamine monomer is 0.5-3% of the sum of the mass of the PVC and the mass of the graphite powder.

3. The method for preparing the 1, 8-naphthalenediamine modified electrode according to claim 2, wherein the amount of the 1, 8-naphthalenediamine monomer is 1% of the sum of the mass of the PVC and the mass of the graphite powder.

4. The method for preparing the 1, 8-naphthalenediamine modified electrode according to any one of claims 1-2, wherein the mass ratio of the PVC to the graphite powder is 1: 15.

5. The use of the 1, 8-naphthalenediamine modified electrode of claim 1 as a silver ion sensor in silver ion detection.

6. The application of the 1, 8-naphthalenediamine modified electrode in silver ion detection according to claim 5, characterized in that the modified electrode is placed in a mixed solution of 0.1mol/L borax base solution and a sample to be detected, open circuit enrichment treatment is performed, the modified electrode is taken out, cleaned, placed in 0.1mol/L HAc-NaAc buffer solution, the potential is set to-0.1V, electrolysis treatment is performed, and the peak current at 0.2V is recorded by anodic stripping voltammetry.

7. The application of the 1, 8-naphthalenediamine modified electrode in silver ion detection according to claim 6, wherein the enrichment time of the enrichment treatment is 15 min.

8. The application of the 1, 8-naphthalenediamine modified electrode in silver ion detection according to claim 6, wherein the rest time of the electrolytic treatment is 60 s.

Technical Field

The invention belongs to the technical field of metal ion detection, and particularly relates to a preparation method of a 1, 8-naphthalene diamine modified electrode and application thereof in silver ion detection.

Background

The silver has antibacterial and bacteriostatic effects, and can be used as disinfectant for drinking water. After water flows through the silver-containing water purifying agent, the content of silver in the water can be obviously increased and can reach 50 mug/L sometimes. Excessive silver intake by the human body can cause poisoning by staining the skin, iris and mucous membranes. The content of silver in drinking water is regulated in China to be not more than 50 mug/L, and the development of an analysis and detection technology of trace silver is necessary.

The national standard adopts Graphite Furnace Atomic Absorption Spectrometry (GFAAS) to analyze drinking water and drinkTrace and trace silver in mineral water is used. In recent years, the application of flow injection and liquid-liquid extraction further improves the detection sensitivity. The flame atomic absorption spectrometry can also be used for measuring trace and trace silver. At present, the conventional methods for measuring silver ions include spectrophotometry, electrochemical analysis, liquid chromatography and the like. The methods have the defects of complex operation, time and labor waste, high detection cost and the like. Wherein in the electrochemical analysis method, the silver ions in water are mainly measured by adopting a chemically modified electrode, calixarene and derivatives thereof, EDTA, BNSAO (Schiff reagent), Dowex (strong silver ion exchange resin), hydrazine derivatives, S₂O₂Thioether is used as a modifier, and has the molecular recognition function on silver ions by utilizing the complexation and other actions of the thioether on the silver ions, so that the silver ions can be enriched on the surface of a modified electrode and then dissolved out by an anode, and the determination method of the silver ions is established. Generally, the electrochemical method has the advantages of simple operation, low detection cost, high sensitivity and the like.

Polydiaminonaphthalene is another novel conductive polymer after polyaniline and polypyrrole, the polymer contains a large amount of active free amino and imino, has the functions of complexing and reduction adsorption on heavy metal ions (such as silver ions, lead ions, mercury ions, copper ions and the like), and has certain practical significance in applying the polynaphthenediamine to the electrochemical method for detecting the silver ions.

Disclosure of Invention

The invention aims to provide a preparation method of a 1, 8-naphthalene diamine modified electrode.

The method specifically comprises the following steps: dissolving 1, 8-naphthalenediamine monomer by using 2-3 drops of acetonitrile, adding PVC powder and a proper amount of tetrahydrofuran, adding graphite powder after the dissolution is complete, uniformly mixing after the solvent is volatilized, pressing the obtained carbon paste-shaped substance into a groove at the top end of an electrode tube, tightly filling, polishing on weighing paper, cleaning with water, placing into 0.10mol/L nitric acid solution for electropolymerization, and airing at normal temperature to obtain the modified electrode.

The performance of the electrode for detecting silver ions is modified by using the dosage image of the 1, 8-naphthalene diamine monomer. The 1, 8-naphthalene diamine monomer is used as a silver ion enriching agent, and the 1, 8-naphthalene diamine monomer doped in the graphite powder is electropolymerized to form a polymer in the carbon paste electrode body. When the dosage of the 1, 8-naphthalene diamine monomer is increased from 0% of the mass sum of the PVC and the graphite powder to 3%, the response value of the electrode pair for enriching ions is gradually increased and then gradually reduced, and the response value is maximized when the dosage of the electrode pair for enriching ions is 1%, namely when the dosage of the 1, 8-naphthalene diamine monomer is 1% of the mass sum of the PVC and the graphite powder, the response performance of the modified electrode pair for silver ions is the best.

Furthermore, the dosage of the 1, 8-naphthalene diamine monomer is 0.5 to 3 percent of the mass sum of the PVC and the graphite powder.

Preferably, the 1, 8-naphthalene diamine monomer is used in an amount of 1% of the sum of the mass of the PVC and the mass of the graphite powder.

Further, the mass ratio of the PVC to the graphite powder is 1: 15.

The invention also aims to provide an application method of the 1, 8-naphthalene diamine modified electrode in silver ion detection.

The 1, 8-naphthylenediamine modified electrode can be used as a silver ion sensor for detecting silver ions in water.

The 1, 8-naphthylenediamine modified electrode prepared by the invention can be used as a working electrode, and a platinum modified counter electrode and a silver-silver hydride modified reference electrode are arranged to prepare a sensor device for detecting silver ions.

The method comprises the steps of putting a modified electrode into a mixed solution of 0.1mol/L borax base solution and a sample to be detected, carrying out open circuit enrichment treatment, taking out the modified electrode, cleaning, putting the modified electrode into 0.1mol/L HAc-NaAc buffer solution, setting the potential to be-0.1V, carrying out electrolysis treatment, and recording the peak current at 0.2V by using an anodic stripping voltammetry.

The enrichment base solution can also be HAc-NaAc, a nitric acid solution, a potassium nitrate solution, a PBS solution and the like, and the influence of the enrichment base solution on the electrode peak current is respectively tested to obtain the conclusion that the borax medium is favorable for measuring the silver ions and the current peak shape is also the best; the conclusion that the peak current is maximum when the borax concentration is 0.1mol/L is obtained by measuring the influence of the borax base solution in the range of 0.05mol/L-0.25mol/L on the electrode peak current, so that 0.1mol/L borax solution is selected as the enrichment base solution.

The invention obtains the conclusion that the HAc-NaAc medium is favorable for measuring silver ions and has the best current peak shape by respectively testing the influence of the detection base solution on the peak current of the electrode; the conclusion that the peak current is maximum when the HAc-NaAc concentration is 0.1mol/L is obtained by measuring the influence of HAc-NaAc base solution in the range of 0.05mol/L-0.25mol/L on the electrode peak current, so that 0.1mol/LHAc-NaAc buffer solution is selected as the detection base solution.

Further, the enrichment time of the enrichment treatment was 15 min.

Further, the rest time of the electrolytic treatment was 60 seconds.

As shown in attached figure 1, the differential pulse voltammogram of the 1, 8-naphthalene diamine modified electrode prepared by the invention in the buffer solution (a) containing silver ions and the blank base solution (b) concretely comprises the steps of placing the modified electrode in 0.1mol/L borax base solution and 10.0mL5.0 × 10^-6And (3) enriching for 15min in a mixed solution of mol/L silver nitrate in an open circuit, taking out and cleaning the electrode, putting the electrode into 0.1mol/LHAc-NaAc buffer solution, setting the potential to be minus 0.1V, carrying out electrolysis treatment for 60s to reduce the silver ions enriched on the electrode into metallic silver, and recording the peak current at the position of 0.2V by using anodic stripping voltammetry. As can be seen from the figure, compared with a blank base solution, the electrode has obvious peak current at 0.2V when detecting a solution containing silver ions, which shows that the 1, 8-naphthalene diamine modified electrode prepared by the invention has obvious electrochemical response to the silver ions.

As shown in fig. 2, it is a dissolution peak diagram (a) and a dissolution peak current variation diagram (b) along with enrichment time of the 1, 8-naphthalene diamine modified electrode prepared by the invention in borax enrichment base solution containing silver ions under different enrichment time conditions. Specifically, under the condition of an open circuit, 0.1mol/L borax solution is used as enrichment base solution, and a modified electrode is used for enriching silver ions. As can be seen from the figure, the magnitude of the dissolution peak current increases with the extension of the enrichment time, and the increase gradually slows after 15min, so the enrichment time of the present invention is preferably 15min for the purpose of obtaining the best enrichment effect in the shortest time.

As shown in figure 3, the elution voltammogram of the 1, 8-naphthylenediamine modified electrode prepared by the invention in HAc-NaAc base solution in silver ion-containing solution under different static time conditions. Specifically, elution voltammograms of the electrode at rest times of 30s, 45s, 60s, 75s, and 90 s. As can be seen from the figure, the peak current gradually increases with the increase of the rest time, and reaches a maximum when the rest time is 60s, and then gradually decreases, because the silver is desorbed on the electrode surface with the increase of the rest time, which affects the detection result. The rest time of the present invention is therefore preferably 60 s.

As shown in figure 4, the linear relation graph of the silver ion solution with different concentrations detected by the 1, 8-naphthalene diamine modified electrode prepared by the invention is shown. The linear regression equation is: i is_p(A)＝8.65×10^-6+9.10mol/L and a correlation coefficient of 0.9982. As can be seen from the figure, the linear range of the electrode for detecting the silver ions is 5.4-540 mug/L, and the detection limit of the electrode for detecting the silver ions is 3.132 mug/L.

The anti-interference test is carried out on the 1, 8-naphthalene diamine modified electrode prepared by the invention.

As shown in FIG. 5, the catalyst is a catalyst containing 1.0 × 10^-60.5mol/L of potassium ions, sodium ions, hydrogen ions, nitrate ions, mercury ions, calcium ions, magnesium ions, zinc ions, boron ions and cadmium ions (100 times), copper ions (100 times), lead ions (100 times) and mercury ions (100 times) are added into the silver ion detection solution, and the silver ion content is measured by using the electrode prepared by the invention, as can be seen from the figure, except 1.0 × 10^-4Besides the influence of the mol/L mercury ions on the detection of the silver ions, other elements do not influence the detection of the silver ions.

In conclusion, the 1, 8-naphthalene diamine modified electrode prepared by the invention can accurately determine the concentration of silver ions under the interference of most heavy metal ions.

The recovery rate of the 1, 8-naphthalene diamine modified electrode prepared by the invention is tested.

Several pieces of 1, 8-naphthylenediamine modified electrodes prepared in the same batch are aligned to 1.0x10^-6And (3) performing standard addition recovery on the silver ion solution of mol/L to obtain the following detection data, wherein RSD% is 2.8(n is 4):

after data are processed, the conclusion can be drawn that the 1, 8-naphthalene diamine modified electrode prepared by the method has good recovery rate.

The invention takes 1, 8-naphthalene diamine as a modifier, prepares a 1, 8-naphthalene diamine modified electrode by adopting a direct mixing method, and carries out electrochemical polymerization in a nitric acid solution of 0.1mol/L to ensure that a 1, 8-naphthalene diamine monomer forms a polymer in a carbon paste electrode body, thereby realizing accurate determination of silver ions and establishing a detection method for determining the silver ions by a differential pulse voltammetry. The electrode has the advantages of high sensitivity, low detection limit, strong anti-interference performance and the like, the linear range of the electrode for measuring silver ions is 5.4-540 mu g/L, and the detection limit is 3.132 mu g/L.

The invention has the beneficial effects that:

(1) the invention adopts a direct mixing method to prepare the 1, 8-naphthylenediamine modified electrode, establishes a differential pulse voltammetry method, applies the differential pulse voltammetry method to the accurate detection of silver ions, and has the advantages of high sensitivity, low detection limit, strong anti-interference capability and the like.

(2) The electrode preparation method is simple and feasible, has low detection cost and simple detection steps, can obtain a detection result in a short time, and does not need special environment and large instruments.

Drawings

The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be obtained on the basis of the following drawings without inventive effort.

FIG. 1 is a differential pulse voltammogram of a 1, 8-naphthalenediamine modified electrode prepared according to the invention in a buffer (a) containing silver ions and a blank base solution (b);

FIG. 2 is a dissolution voltammogram (a) and a dissolution peak current variation graph (b) along with enrichment time of a 1, 8-naphthalene diamine modified electrode prepared by the invention in borax enrichment base solution containing silver ions under different enrichment time conditions;

FIG. 3 is a dissolution voltammogram of the 1, 8-naphthalene diamine modified electrode prepared by the invention in HAc-NaAc base solution in silver ion-containing solution under different resting time conditions;

FIG. 4 is a linear relationship diagram of silver ion solutions with different concentrations detected by the 1, 8-naphthalene diamine modified electrode prepared by the invention;

FIG. 5 is an anti-interference test chart for detecting silver ions by using the 1, 8-naphthalene diamine modified electrode prepared by the invention.

Detailed Description

In order that the objects, aspects and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the following detailed description and the accompanying drawings.