Simulation system for predicting presence of weld metal ions in a water delivery pipe having a weld and applications thereof

Abstract

The application provides a simulation system for predicting the presence of weld metal ions in a water conveying pipeline with a weld and application thereof. The simulation system comprises an electrochemical workstation and a three-electrode system in electrical connection with the electrochemical workstation and located in an electrolyte solution, the three-electrode system comprising a working electrode, an auxiliary electrode and a reference electrode, wherein the working electrode is an inert platinum sheet electrode with a weld metal component simulation coating on at least one side surface, the reference electrode is an Ag / AgCl / KCl reference electrode, and the auxiliary electrode is a platinum electrode; wherein the weld metal component simulation coating comprises a weld metal component, a conductive agent and a binder. Through the simulation system of the application, whether weld metal ions exist in the water conveying pipeline can be predicted in advance and actively.

Description

Technical Field

[0001] This application relates to the field of pipeline electrochemical technology, and more particularly to a simulation system for predicting the presence of weld metal ions in water pipelines with welds and its application. Background Technology

[0002] Current water pipelines require welding connections, primarily using lead-tin solder. This solder can cause galvanic corrosion between itself and the copper water pipes, releasing metals such as lead and tin into the water and causing heavy metal pollution.

[0003] Current research on monitoring the release of heavy metal ions in water pipelines mainly employs a combination of online monitoring instruments and periodic laboratory sampling. However, this method focuses on monitoring the current state and cannot proactively predict future release behavior. Moreover, the appearance and composition changes of the weld during the reaction process are very minor, and the concentration of metal ions released in the short term is also very low, making it difficult to directly examine the reaction of the weld itself. In addition, the overall conductivity of the weld is very poor, and its rough and irregular shape seriously affects the stability of the electrochemical signal, making it impossible to directly use the actual weld as an electrode material.

[0004] Therefore, there is a need for an improved simulation system for predicting the presence of weld metal ions in water pipelines with welds and its application. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0006] In one aspect, this application provides a simulation system for predicting the presence of weld metal ions in a water pipeline with welds, comprising an electrochemical workstation and a three-electrode system electrically connected to the electrochemical workstation and located in an electrolyte solution, the three-electrode system comprising a working electrode, an auxiliary electrode, and a reference electrode. The working electrode is an inert platinum sheet electrode with a weld metal composition simulation coating on at least one side surface, the reference electrode is an Ag / AgCl / KCl reference electrode, and the auxiliary electrode is a platinum electrode. The weld metal component simulated coating includes weld metal components, conductive agents, and adhesives.

[0007] In one exemplary embodiment, the weld metal component is selected from lead, tin, and lead-tin alloys, the conductive agent is graphite powder, and the binder is a perfluorosulfonic acid-based polymer.

[0008] In one exemplary embodiment, the surface area of ​​the inert platinum sheet electrode is 0.5-1 cm². 2 The thickness is 0.05-0.1 mm.

[0009] In one exemplary embodiment, the thickness of the weld metal composition simulated coating is 0.05 mm to 0.1 mm.

[0010] In one exemplary embodiment, the mass ratio of the weld metal component to the conductive agent is 1:1 to 1:2.

[0011] In one exemplary embodiment, the electrolyte solution is selected from tap water, purified water, an aqueous solution containing at least one of hydrogen ions, hydroxide ions, calcium ions, magnesium ions, chloride ions, sulfate ions, nitrate ions, bicarbonate ions, and carbonate chloride ions, with a concentration of 0.1-50 mmol / L, or purified water; and / or, The pH value of the electrolyte solution is 6.5-8.5.

[0012] In an exemplary embodiment, the working electrode is prepared by the following steps: S1: Mix the weld metal components and the conductive agent in anhydrous ethanol, stir until the mixture is uniform, then add the binder solution and continue stirring until uniform to obtain a suspension for coating. S2: The suspension is coated onto an inert platinum sheet electrode such that the suspension covers one or both surfaces of the inert platinum sheet electrode. S3: Place the coated electrode in a cool place to air dry naturally to obtain the working electrode.

[0013] On the other hand, this application provides the application of the above-mentioned simulation system in predicting the presence of weld metal ions in water pipelines with welds.

[0014] In one exemplary embodiment, the application includes: The corrosion current of the weld metal composition is measured daily using a three-electrode system over a period of time, and the corrosion rate of the weld metal composition is obtained according to Formula I: (I) Where CR is the corrosion rate (mm / a), EQ is the material chemical equivalent = relative atomic mass of the metal element / valence of the metal ions generated at the anode (g / eq), and i corr Corrosion current density (A / cm) 2 A is the electrode area (cm²) 2 ), d is the metal density (g / cm³) 3 ); At the end of the time period, the water conditions in the water supply pipeline are changed, the corrosion current is measured, and the corrosion rate is calculated. If the corrosion rate exceeds a set threshold, the presence of weld metal ions in the pipeline water is predicted.

[0015] In this application, the time period is typically 5-7 days, which ensures that the simulation system meets the requirements for system measurement stability when used in actual test scenarios.

[0016] In this application, the corrosion rate may change due to the aging of the weld metal and the potential for reaction to be hindered by the surface oxide layer. The threshold value can be determined comprehensively using conventional methods in the art, based on actual conditions and long-term monitoring data.

[0017] In this application, the corrosion current can be measured using methods commonly used in the field, such as the polarization curve method.

[0018] In one exemplary embodiment, altering the pipe water conditions in the water supply pipeline includes increasing the chloride ion concentration, increasing the alkalinity of the pipe water, and increasing the sulfate ion concentration in the pipe water.

[0019] This application employs a three-electrode system with an inert platinum sheet electrode having a coating simulating weld metal composition as the working electrode to monitor the corrosion current of a simulated weld.

[0020] This application utilizes the phenomenon that galvanic corrosion current intensifies when water conditions such as chloride ion concentration and sulfate ion concentration change. By measuring the electrochemical corrosion signals of the solder metal components, such as corrosion current and corrosion rate, and based on the lag of the released weld metal ion concentration values ​​relative to the changes in the corrosion current and corrosion rate values ​​of the weld metal, the potential risk of heavy metal release can be predicted in advance.

[0021] The working electrode prepared in this application has good conductivity and reactivity, can accurately simulate the composition and structural characteristics of metal welds, and can obtain sensitive electrical signals in electrochemical tests.

[0022] This application provides a simulation system that uses solder metal as an electrode to directly simulate the electrochemical reaction at the connection of actual metal pipes, thus better integrating electrochemical methods into the study of the oxidation release characteristics of metal solder.

[0023] The reaction system of this application differs from the traditional three-electrode system used to study the corrosion process of metal pipes. It can independently study the anolyte metal without relying on the cathode reaction and has good test stability.

[0024] This application provides an electrochemical method for studying the reaction characteristics at metal pipe joints, which enables the prediction of the release of heavy metal ions from the solder by monitoring the electrochemical oxidation process of the solder metal.

[0025] In the method for preparing the working electrode, this application improves the conductivity and stability of the simulated solder electrode by adding conductive agents and binders. The resulting simulated solder electrode has good conductivity and reactivity, and can obtain sensitive electrical signals and accurate test results in electrochemical testing.

[0026] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application may be realized and obtained by means of the methods described in the description. Attached Figure Description

[0027] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0028] Figure 1 This is a schematic diagram of the structure of the simulation system provided in Embodiment 2 of this application; Figure 2 A schematic diagram of the structure of the simulated coating of the simulation system provided in Embodiment 2 of this application; and Figure 3 The time-corrosion current-lead concentration relationship curve of the working electrode prepared for Example 2 of this application in the water quality change test experiment.

[0029] Marked in the image: 1. Working electrode; 11. Inert platinum sheet electrode; 12. Weld metal composition simulation coating; 2. Ag / AgCl / KCl reference electrode; 3. Inert platinum sheet auxiliary electrode; 4. Reaction vessel; 5. Electrochemical workstation; 6. Signal receiving and processing system. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application are described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.

[0031] Figure 1 This is a schematic diagram of the simulation system provided in Embodiment 2 of this application. Figure 1As shown, the simulation system includes a working electrode 1, an Ag / AgCl / KCl reference electrode 2, an inert platinum sheet auxiliary electrode 3, a reaction vessel 4, and an electrochemical workstation 5. The reaction vessel 4 contains an electrolyte solution, which can be tap water or an artificially prepared aqueous solution containing chloride ions, sulfate ions, and nitrates at a concentration of 0.1-50 mmol / L. The working electrode 1, the Ag / AgCl / KCl reference electrode 2, and the inert platinum sheet auxiliary electrode 3 are all connected to the electrochemical workstation 5 via wires. The electrochemical workstation 5 is also connected to a signal receiving and processing system 6.

[0032] like Figure 2 As shown, the working electrode 1 includes an inert platinum sheet electrode 11, the surface area of ​​which is 1.0 cm². 2 The inert platinum sheet electrode 11 has a thickness of approximately 0.2 mm. A weld metal composition simulation coating 12, approximately 0.05 mm thick, is provided on both sides of the inert platinum sheet electrode 11. This welding metal composition simulation coating contains actual metal solder. Furthermore, the welding metal composition simulation coating also contains graphite and a binder, with the graphite uniformly distributed within the coating. The preparation process of this working electrode 1 can involve uniformly mixing solder powder and graphite powder in anhydrous ethanol, then adding a perfluorosulfonic acid-based polymer solution as a binder, and stirring until a coating suspension is obtained. This coating suspension is then uniformly coated onto the inert platinum sheet electrode, completely covering both sides of the electrode, ensuring a smooth electrode surface after coating. The electrode is then allowed to air dry naturally in a cool place.

[0033] Unless otherwise specified, all materials used in the following examples and comparative examples are commercially available.

[0034] Example 1 (1) Take a brass water pipe welded with lead-tin solder, peel off a small piece of weld material at the weld with a ceramic knife, carefully rinse with tap water to remove loose deposits on the surface, dry in an oven at 40 ℃, and then grind in a mortar until it can pass through a 300-mesh sieve to obtain lead-tin solder powder. (2) Take 0.10 g of finely ground lead-tin solder powder and mix it with 0.20 g of analytical grade graphite powder in 5 mL of anhydrous ethanol. Stir until the two powders are evenly mixed. Then add about 50 μL of 5% perfluorosulfonic acid polymer solution (this solution is a standard - DuPont Nafion solution) as a binder and continue to stir evenly to obtain a suspension for coating. (3) Using a glass rod, dip into the coating suspension and quickly and evenly coat it onto a surface area of ​​approximately 1.0 cm². 2The coating is applied to an inert platinum sheet electrode, ensuring that it completely covers both sides of the inert platinum sheet substrate with uniform thickness, and that the coated electrode surface remains flat. (4) Place the coated electrode in a cool place to air dry naturally for more than 10 minutes to obtain the working electrode for the experimental device. The thickness of the corresponding inert platinum sheet electrode is about 0.1 mm, and the thickness of the weld metal composition simulation coating is 0.05 mm. (5) The working electrode prepared above, together with the uncoated inert platinum sheet electrode and the Ag / AgCl / KCl reference electrode, are put into the reaction vessel and fixed to obtain a three-electrode system. The electrodes are connected to the electrochemical workstation with wires to obtain the simulation system.

[0035] Example 2 (1) Grind the analytical grade Pb powder until it can pass through a 300-mesh sieve; (2) Take 0.10 g of finely ground Pb powder and mix it with 0.10 g of analytical grade graphite powder in 5 mL of anhydrous ethanol. Stir until the two powders are evenly mixed. Then add about 50 μL of 5% perfluorosulfonic acid polymer solution (this solution is a standard - DuPont Nafion solution) as a binder and continue to stir evenly to obtain a suspension for coating. (3) Use a glass rod to dip into the coating suspension and evenly coat it on the inert platinum sheet electrode with a surface area of ​​about 1.0 cm2, so that it completely covers both sides of the inert platinum sheet electrode and the coating thickness is uniform. The electrode surface after coating is also flat. (4) Place the coated electrode in a cool place to air dry naturally for more than 10 minutes to obtain the working electrode for the experimental device. The thickness of the corresponding inert platinum sheet electrode is about 0.1 mm, and the thickness of the weld metal composition simulation coating is 0.05 mm. (5) The working electrode prepared above, together with the uncoated inert platinum sheet electrode and the Ag / AgCl / KCl reference electrode, are placed into the reaction vessel and fixed to obtain a three-electrode system. Each electrode is then connected to an electrochemical workstation using wires to obtain a simulation system, such as... Figure 1 and Figure 2 As shown.

[0036] Experimental method: Figure 1 The simulated system shown monitors changes in corrosion current daily and samples the water for lead ion concentration. On the fifth day, the chloride ion concentration in the water was increased, and an increase in corrosion current was observed on the same day. Subsequently, an increase in lead ion concentration was observed on the tenth day.

[0037] from Figure 3It can be seen that when the chloride ion concentration in the water was increased from 30 mg / L to 100 mg / L on the fifth day, the corrosion current was observed to increase from 0.5 μA / cm on that day. 2 Increased to 1.2 μA / cm 2 The lead ion concentration in the water increased from 12 μg / L to 20 μg / L on the tenth day, and then rose to 45 μg / L. Calculations based on the corrosion rate show that lead corrosion accelerates with increasing corrosion current, but the increase in lead concentration in the water has a lag effect. Therefore, the release of ions from the weld metal can be predicted based on the corrosion rate.

[0038] Electrochemical reaction equation: (I) Where CR is the corrosion rate (mm / a), EQ is the material chemical equivalent = relative atomic mass of the metal element / valence of the metal ions generated at the anolyte (g / eq), and icorr is the corrosion current density (A / cm). 2 A is the electrode area (cm²) 2 ), d is the metal density (g / cm³) 3 ).

[0039] In this embodiment, the threshold is set to 0.1 mm / a, where a represents a year (time).

[0040] Example 3 (1) Grind the analytical grade Sn powder until it can pass through a 300-mesh sieve; (2) Take 0.10 g of finely ground Sn powder and mix it with 0.10 g of analytical grade graphite powder in 5 mL of anhydrous ethanol. Stir until the two powders are evenly mixed. Then add about 50 μL of 5% perfluorosulfonic acid polymer solution (this solution is a standard - DuPont Nafion solution) as a binder and continue to stir evenly to obtain a suspension for coating. (3) Use a glass rod to dip into the coating suspension and evenly coat it on the inert platinum sheet electrode with a surface area of ​​about 1.0 cm2, so that it completely covers both sides of the inert platinum sheet electrode and the coating thickness is uniform. The electrode surface after coating is also flat. (4) Place the coated electrode in a cool place to air dry naturally for more than 10 minutes to obtain the working electrode for the experimental device. The thickness of the corresponding inert platinum sheet electrode is about 0.1 mm, and the thickness of the weld metal composition simulation coating is 0.05 mm. (5) The working electrode prepared above, together with the uncoated inert platinum sheet electrode and the Ag / AgCl / KCl reference electrode, are put into the reaction vessel and fixed to obtain a three-electrode system. The electrodes are connected to the electrochemical workstation with wires to obtain a simulation system.

[0041] Comparative Example 1 For brass water supply pipes welded with lead-tin solder, a small piece of solder material is peeled off at the weld joint using a ceramic knife, carefully rinsed with tap water to remove loose deposits on the surface, dried in an oven at 40 ℃, and then ground in a mortar until it can pass through a 300-mesh sieve to obtain lead-tin solder powder. Using a powder press, the above lead-tin solder powder is pressed into circular sheets with a diameter of 1.0 cm and a thickness of about 0.2 cm under a pressure of 10 MPa. The powder is pressed into a tablet and connected to a copper wire using conductive adhesive to obtain a working electrode.

[0042] The working electrode prepared in Comparative Example 1 was also applied to, for example... Figure 1 In the simulation system shown, it was found that the working electrode had poor conductivity and a stable electrochemical signal could not be measured.

[0043] In the preparation process of the working electrode of this application, an inert platinum sheet electrode is used as the basis, and a solder layer is set on the surface of the inert platinum sheet electrode. In addition to solder metal simulation powder, conductive agent and conductive binder are added to the solder layer. Moreover, the thickness of the solder layer obtained by the uniform coating method of this application is also very small.

[0044] The working electrode of this application has both good conductivity and reactivity, and its small electrode area enables sensitive electrical signals to be obtained in electrochemical tests, resulting in accurate test results.

[0045] While the embodiments disclosed in this application are as described above, the content is merely for the purpose of facilitating understanding of this application and is not intended to limit this application. Any person skilled in the art to which this application pertains may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application; however, the scope of protection of this application shall still be determined by the scope defined in the appended claims.

Claims

1. A simulation system for predicting the presence of weld metal ions in a water pipeline with welds, characterized in that, It includes an electrochemical workstation and a three-electrode system electrically connected to the electrochemical workstation and located in an electrolyte solution, the three-electrode system including a working electrode, an auxiliary electrode, and a reference electrode. The working electrode is an inert platinum sheet electrode with a weld metal composition simulation coating on at least one side surface, the reference electrode is an Ag / AgCl / KCl reference electrode, and the auxiliary electrode is a platinum electrode. The weld metal component simulated coating includes weld metal components, conductive agents, and adhesives.

2. The simulation system according to claim 1, characterized in that, The weld metal composition is selected from lead, tin, and lead-tin alloys, the conductive agent is graphite powder, and the binder is a perfluorosulfonic acid-based polymer.

3. The simulation system according to claim 1 or 2, characterized in that, The surface area of ​​the inert platinum sheet electrode is 0.5-1 cm². 2 The thickness is 0.05-0.1 mm.

4. The simulation system according to claim 1 or 2, characterized in that, The thickness of the simulated coating for the weld metal composition is 0.05 mm to 0.1 mm.

5. The simulation system according to claim 1 or 2, characterized in that, The mass ratio of the weld metal component to the conductive agent is 1:1 to 1:

2.

6. The simulation system according to claim 1 or 2, characterized in that, The electrolyte solution is selected from tap water, purified water, and aqueous solutions containing at least one of the following: hydrogen ions, hydroxide ions, calcium ions, magnesium ions, chloride ions, sulfate ions, nitrate ions, bicarbonate ions, and carbonate chloride ions, with a concentration of 0.1-50 mmol / L; and / or, The pH value of the electrolyte solution is 6.5-8.

5.

7. The simulation system according to claim 1 or 2, characterized in that, The working electrode is prepared by the following steps: S1: Mix the weld metal components and the conductive agent in anhydrous ethanol, stir until the mixture is uniform, then add the binder solution and continue stirring until uniform to obtain a suspension for coating. S2: The suspension is coated onto an inert platinum sheet electrode, such that the suspension covers one or both surfaces of the inert platinum sheet electrode; and S3: Place the coated electrode in a cool place to air dry naturally to obtain the working electrode.

8. The application of the simulation system according to any one of claims 1-7 in predicting the presence of weld metal ions in water pipelines with welds.

9. The application according to claim 8, characterized in that, The applications include: The corrosion current of the weld metal composition is measured daily using a three-electrode system over a period of time, and the corrosion rate of the weld metal composition is obtained according to Formula I: （I） Where CR is the corrosion rate (mm / a), EQ is the material chemical equivalent = relative atomic mass of the metal element / valence of the metal ions generated at the anode (g / eq), and i corr Corrosion current density (A / cm) 2 A is the electrode area (cm²) 2 ), d is the metal density (g / cm³) 3 ); At the end of the time period, the water conditions in the water supply pipeline are changed, the corrosion current is measured, and the corrosion rate is calculated. If the corrosion rate is greater than a set threshold, the presence of weld metal ions in the pipeline water is predicted.

10. The application as described in claim 8, characterized in that, Changing the water conditions in the water supply pipeline includes increasing the chloride ion concentration, increasing the alkalinity of the water, and increasing the sulfate ion concentration in the water.

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