Recyclable Ag / AgCl reference electrode convenient to disassemble and overhaul

Abstract

The utility model discloses an Ag / AgCl reference electrode convenient to disassemble and overhaul and capable of being recycled. The Ag / AgCl reference electrode comprises an Ag wire, a glass sleeve and a porous plug, the Ag wire is fixed in the glass sleeve through the Parafilm sealing film, a KCl solution is contained in the glass sleeve, the porous plug is sintered at the tail end of the glass sleeve, and an AgCl coating is plated on the surface, in contact with the KCl solution, of the Ag wire; and the upper part of the Ag wire extends out of the orifice of the glass sleeve. According to the Ag / AgCl reference electrode convenient to disassemble and overhaul and capable of being recycled, the electrode adopts a brand new assembly form, the electrode can be maintained in time when the performance of the electrode is reduced after long-time use, the maintenance process of the electrode is simpler, more convenient and easier to operate, the use frequency of the electrode is effectively increased, and the service life of the electrode is prolonged. And the use cost of the electrode is reduced.

Description

Technical Field

[0001] The utility model discloses and relates to the technical field of Ag / AgCl reference electrode preparation, in particular to an Ag / AgCl reference electrode which is easy to disassemble and repair and can be recycled. Background Art

[0002] In scientific experiments, electrochemical applications, and other fields, reference electrodes provide a stable potential baseline for the measurement system, ensuring accuracy and repeatability and reducing the impact of external interference on measurement results. Currently, the main reference electrodes available on the market include hydrogen electrodes, calomel electrodes, mercurous sulfate electrodes, mercuric oxide electrodes, and silver chloride (Ag / AgCl) electrodes. Compared to other electrodes, Ag / AgCl (silver / silver chloride) electrodes are widely used due to their improved stability (such as high temperature resistance), adaptability to electrolyte environments (including acidic, alkaline, and neutral solutions), and regeneration. However, a common issue with Ag / AgCl reference electrodes is their limited service life. Over time, the electrode's performance degrades and its potential deviates from the standard electrode potential. Because commercially available electrodes are very compact and difficult to disassemble, electrode regeneration becomes a challenge, making maintenance very difficult. Utility Model Content

[0003] In view of this, the present invention discloses a Ag / AgCl reference electrode structure that is easy to disassemble and repair and can be recycled. When the performance of the electrode deteriorates after long-term use, it can be maintained in time.

[0004] The technical solution provided by the utility model is specifically a Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled, comprising: Ag wire, Parafilm sealing film, glass sleeve, AgCl coating, KCl solution, and porous plug;

[0005] The Ag wire is fixed in a glass sleeve through a Parafilm sealing film. The glass sleeve contains a KCl solution, and the porous plug is sintered at the end of the glass sleeve. The surface of the Ag wire in contact with the KCl solution is plated with an AgCl coating. The upper part of the Ag wire extends out of the tube mouth of the glass sleeve.

[0006] Preferably, it also includes a rubber or silicone cap, which is placed outside the glass sleeve and covered on the Parafilm sealing film, and one end of the silver wire passes through the rubber or silicone cap and out of the tube mouth of the glass sleeve.

[0007] Preferably, the AgCl coating on the surface of the Ag wire is obtained by electroplating using a potentiostat.

[0008] Preferably, the Ag wire has a diameter of 0.8-1 mm and a length of 7-8 cm.

[0009] Preferably, the volume of the KCl solution is greater than the solubility of the glass sleeve, and the excess portion is concentrated in the form of droplets at the orifice of the glass sleeve.

[0010] Preferably, the Parafilm sealing film is tightly wrapped around the Ag wire and the opening of the glass sleeve, so that the Ag wire is fixed in the glass sleeve through the Parafilm sealing film.

[0011] Preferably, the porous plug is one of a porous glass sand core, a ceramic core, and a porous polytetrafluoroethylene plug.

[0012] Preferably, the KCl solution is saturated potassium chloride or a KCl solution of other specified concentrations.

[0013] The utility model provides a recyclable Ag / AgCl reference electrode that is easy to disassemble and repair. The Ag / AgCl reference electrode uses a whole silver wire partially covered with an AgCl coating, eliminating the need for Cu wire welding and simplifying the process. Because the electrode in the utility model is disassembled, the performance of the Ag / AgCl reference electrode can be restored after re-electroplating, providing a stable potential for the system. This extends the service life of the Ag / AgCl reference electrode, reduces costs, and is environmentally friendly.

[0014] The utility model provides an Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled. The electrode adopts a new assembly form, so that when the performance of the electrode deteriorates during long-term use, it can be promptly maintained. The electrode can maintain a stable potential and be used multiple times. That is, the electrode provided by the utility model is not only a highly stable Ag / AgCl electrode, but also has a simpler and easier maintenance process, which effectively increases the number of times the electrode can be used and reduces the cost of using the electrode.

[0015] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory and are not restrictive of the disclosure of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention.

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 A schematic diagram of the decomposed structure of an Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled, provided in an embodiment of the present utility model;

[0019] Figure 2 A schematic diagram of the appearance and structure of an Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled, provided in an embodiment of the present utility model;

[0020] Figure 3 Schematic diagram of electrochemical preparation of silver wire covered with AgCl coating provided in the disclosed embodiment of the present utility model;

[0021] Figure 4 The cyclic voltammograms of the commercially available electrode, the assembled electrode, and the repaired electrode provided in the disclosed embodiments of the present invention are shown. DETAILED DESCRIPTION

[0022] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with certain aspects of the present invention, as detailed in the appended claims.

[0023] In order to solve the problem in the prior art that the electrode has a limited service life and cannot be regenerated, and is inconvenient to repair, Figure 1-2 As shown, this embodiment provides an Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled, including: an Ag wire 1, a Parafilm sealing film 3, a glass sleeve 4, an AgCl coating 5, a KCl solution 6, and a porous plug 7;

[0024] The Ag wire 1 is fixed in a glass sleeve by a Parafilm sealing film 3. The glass sleeve contains a KCl solution 6 to ensure that the solution completely fills the entire glass sleeve and no bubbles are present. The porous plug is sintered at the end of the glass sleeve, and the surface of the Ag wire 1 in contact with the KCl solution 6 is plated with an AgCl coating 5.

[0025] To meet aesthetic requirements, a rubber or silicone cap can be placed outside the glass cannula and covered on the Parafilm sealing film. One end of the silver wire passes through the rubber or silicone cap, and the upper part of the Ag wire 1 extends outside the tube opening of the glass cannula. The rubber or silicone cap completely covers the outside of the Parafilm sealing film.

[0026] This embodiment uses Parafilm sealing film 3 to encapsulate the glass cannula 4. Due to its excellent elasticity and ductility, Parafilm sealing film 3 can easily wrap around containers of various shapes and sizes, providing a reliable seal. Parafilm sealing film 3 also has excellent chemical resistance, resisting corrosion from some solvents and chemical reagents, protecting experimental samples. Based on these two advantages, this packaging method achieves the same effectiveness as the commercially available polytetrafluoroethylene cap sealing of Ag / AgCl reference electrodes, while offering the added benefit of easy disassembly.

[0027] Preferably, the Ag wire 1 has a diameter of 0.8-1 mm and a length of 7-8 cm.

[0028] Preferably, the volume of the KCl solution 6 is greater than the solubility of the glass sleeve, and the excess portion is accumulated in the form of droplets at the opening of the glass sleeve.

[0029] Preferably, the Parafilm sealing film 3 is tightly wrapped around the Ag wire 1 and the opening of the glass sleeve, so that the Ag wire is fixed in the glass sleeve through the Parafilm sealing film.

[0030] Preferably, the KCl solution 6 is saturated potassium chloride or a KCl solution of other specified concentrations.

[0031] The electrode maintenance process involves disassembling the rubber or silicone cap 2, the Parafilm sealing film 3, and the silver wire covered with the AgCl coating. The Ag / AgCl wire is then polished and ready for secondary electrochemical plating. The secondary electrochemical plating process involves using coarse sandpaper to remove the coating from the silver wire, followed by polishing with metallographic sandpaper, and finally repeated washing with anhydrous ethanol and distilled water.

[0032] The electrode potential provided in this embodiment is subjected to cyclic voltammetry detection before use to ensure that the potential remains unchanged during use. If potential deviation occurs, timely maintenance is required.

[0033] The specific assembly and preparation of the electrode of this embodiment includes the following steps:

[0034] Insert the coated part of the prepared silver wire covered with AgCl into the KCl solution of the glass sleeve, and the top of the uncoated Ag wire is located outside the tube mouth of the glass sleeve;

[0035] Ensure that the KCl solution in the glass cannula exceeds the cannula's capacity, allowing the excess to collect as droplets at the cannula's opening. Cut the Parafilm to approximately 5 mm wide and 5-7 cm long. While stretching, wrap the Parafilm tightly around the Ag wire and the cannula's opening. Then, insert a rubber or silicone cap over the end of the silver wire and place it over the Parafilm.

[0036] As the use time and number of times increase, when the potential of the Ag / AgCl electrode shifts (the reference electrode will be subjected to cyclic voltammetry before use to ensure that the potential remains unchanged during use), or the AgCl coating turns white to the naked eye, the electrode needs to be disassembled, regenerated and reassembled. Because the external rubber or silicone cap is elastic, the Parafilm film is also very easy to disassemble, because the silver wire covered with the AgCl coating can be easily taken out for secondary electrochemical plating. The specific steps are: first grind off the coating with coarse sandpaper, and then polish with metallographic sandpaper. The treated silver wire is repeatedly washed with anhydrous ethanol and distilled water (ultrasonic environment vibration) 2-3 times. Then the Ag wire and platinum wire are connected to the positive and negative poles of the constant potential instrument as the anode and cathode respectively.

[0037] Preferably, the AgCl coating plated on the surface of the Ag wire is obtained by using a potentiostat to utilize an electroplating method. The electroplating conditions are: the plating solution is a salt or acid solution containing chloride ions, the silver wire is connected to the positive pole of the potentiostat, and the platinum wire is connected to the negative pole of the potentiostat for electroplating. The voltage is adjusted to be at the underpotential oxidation voltage of the Ag wire, and this electroplating state is maintained for about 3 days. The silver wire can be used to be connected to the positive pole of the potentiostat simultaneously with one or several silver wires for electroplating simultaneously. The electroplating voltage still needs to be maintained at the underpotential oxidation potential of each silver wire. After 3-4 days, it will be found that the AgCl coating has fully covered the solution immersion end of the Ag wire. At this time, the prepared Ag / AgCl wire is encapsulated according to the above steps to complete a complete Ag / AgCl reference electrode. After electrochemical calibration again, it is immersed in a saturated potassium chloride solution and stored for use.

[0038] The present invention is further explained below with reference to specific embodiments, but is not intended to limit the scope of protection of the present invention.

[0039] Example 1

[0040] like Figure 3 , electrochemistry of silver wire covered with AgCl coating: Note: The voltage provided by the constant potential instrument is related to the number of silver wires, and there is no restriction on the voltage provided by the constant potential instrument and the number of silver wires.

[0041] Electrode assembly and disassembly

[0042] Prepare a glass cannula with a porous glass sand core / ceramic core / polytetrafluoroethylene porous plug end capping.

[0043] Use a syringe to inject a KCl solution of a specified concentration into the glass cannula. In this example, a saturated potassium chloride solution is injected. Ensure that the KCl solution in the glass cannula exceeds the cannula's volume capacity, with the excess solution collecting in the form of droplets at the cannula's mouth. Simultaneously, add KCl crystals to the glass cannula.

[0044] The coated part of the prepared silver wire covered with AgCl coating is inserted into the KCl solution of the glass sleeve, and the top of the uncoated Ag wire is located outside the tube mouth of the glass sleeve.

[0045] Cut a piece of Parafilm approximately 5 mm wide and 5-7 cm long. While stretching, wrap the Parafilm tightly around the Ag wire and the tube opening. Ensure there are no bubbles in the glass tube. Then, insert a rubber or silicone cap with a hole in the middle through the end of the silver wire and over the Parafilm.

[0046] As the use time and frequency increase, when the potential of the Ag / AgCl electrode shifts (the reference electrode is tested for cyclic voltammetry before use to ensure that the potential remains unchanged during use), or the AgCl coating turns white to the naked eye, it is necessary to disassemble the electrode parts and re-prepare them. First, remove the elastic rubber or silicone cap on the outside, disassemble the Parafilm covering the tube mouth, take out the silver wire covered with the AgCl coating, grind off the coating with coarse sandpaper, polish with metallographic sandpaper, repeatedly wash with anhydrous ethanol and double distilled water, and then perform secondary electroplating and assembly according to the above electrochemical steps.

[0047] The assembled Ag / AgCl reference electrode was tested using a three-electrode system. The counter electrode was a platinum wire, the working electrode was a polished glassy carbon electrode, and the reference electrode was a new electrode assembled using this patented process. The electrolyte was K3Fe(CN)6(1*10 -3 mol·L -1 )+KCl(0.5mol·L -1 ) solution. Cyclic voltammetry was used to detect the reference electrode, such as Figure 4 As shown, it can be concluded that the potential provided by the new electrode after assembly is consistent with that provided by the commercially available electrode.

[0048] The present invention and its embodiments are described above, wherein the rubber sleeve or silicone sleeve is optional and is mainly used to ensure the appearance of the product; the concentration of KCl in the glass sleeve is not limited to the saturation concentration and can also be the commonly used 3 mol.L -1The glass cannula has a porous plug at the end, which may be a glass frit, ceramic core, or porous polytetrafluoroethylene. During silver wire electroplating, the potential provided by the potentiostat should be adjusted appropriately based on the number of silver wires being plated. The plating solution can be more than KCl; HCl is also acceptable. The concentration is not limited to 0.1 M and can be increased. However, the Ag / AgCl reference electrode prepared using the method selected in the examples is the most stable during use and maintains its potential the longest.

[0049] Example 2

[0050] Repair and regeneration of commercially available electrodes:

[0051] Prepare a commercially available Ag / AgCl reference electrode with a polytetrafluoroethylene cap (this electrode has the appearance of a common commercially available electrode product) that has already undergone potential shift. Because the assembly method of currently available commercial reference electrodes is very tight, it is usually difficult to disassemble manually at room temperature. However, under heating conditions (such as placing the electrode in an oven and heating it to about 150 degrees for 30 minutes), the polytetrafluoroethylene cap and the electroplated Ag wire (including copper terminals) in the middle can be removed with pliers by taking advantage of the difference in thermal expansion and contraction coefficients between glass and polytetrafluoroethylene. After grinding off the coating with coarse sandpaper, polish with metallographic sandpaper, repeatedly rinse with anhydrous ethanol and double-distilled water, and then perform secondary electroplating according to the above electrochemical steps.

[0052] The electroplated Ag wire is assembled into a complete electrode according to the assembly method in Example 1 of this patent.

[0053] The assembled Ag / AgCl reference electrode was tested using a three-electrode system. The counter electrode was a platinum wire, the working electrode was a polished glassy carbon electrode, and the reference electrode was each repaired electrode assembled using this patented process. The electrolyte was K3Fe(CN)6(1*10 -3 mol·L -1 )+KCl(0.5mol·L -1 ) solution. Cyclic voltammetry was used to detect the reference electrode.

[0054] The above describes the present invention and its implementation methods. This description limits the types of commercially available reference electrodes to Ag / AgCl reference electrodes and is not restrictive to manufacturers. The appearance of the commercially available electrodes designed by the present invention is not limited to the electrode style with a polytetrafluoroethylene cap. As long as the electrodes can be disassembled by extreme methods such as heating, they can be repaired using the method in Example 2. The disassembly method of commercially available electrodes is not limited to heating. Among them, the rubber sleeve or silicone sleeve is not a must, mainly to ensure the beautiful appearance of the product. There is no restriction on the saturated concentration of KCl in the glass sleeve, and it can also be the commonly used 3 mol.L -1The end of the glass cannula is a porous plug, not limited to glass frit, ceramic core, or porous polytetrafluoroethylene. The potential provided by the potentiostat for silver wire electroplating can be appropriately increased or decreased depending on the amount of silver wire being electroplated. The plating solution can be more than KCl; HCl is also acceptable. The concentration is not limited to 0.1 M and can be increased. However, the Ag / AgCl reference electrode prepared using the method selected in the examples is the most stable during use and maintains the potential the longest. Figure 4 The cyclic voltammograms shown in the figure correspond to the following electrodes: A: commercial electrode; B: first assembled electrode; C: second assembled electrode 2; D: first repaired electrode; E: second repaired electrode;

[0055] By combining an improved Ag / AgCl reference electrode assembly technology of this embodiment with the AgCl electroplating process of silver wire, the convenience and operability of electrode maintenance under mild conditions are achieved when the electrode performance declines, and the electrode can be used multiple times after maintenance. By comparing cyclic voltammetry with commercially available reference electrodes, the consistency of the output potential of the homemade and repaired electrodes with that of commercially available electrodes is ensured. The above-mentioned electrode structure not only simplifies the assembly method of the Ag / AgCl reference electrode, but also makes subsequent maintenance more convenient and operational, increases the number of times the electrode is used, thereby effectively increasing the service life of the electrode and reducing the cost of use. Figure 4 As shown, the assembled electrodes and repaired electrodes provided in this embodiment are different from commercially available electrodes.

[0056] Those skilled in the art will readily envision other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only; the true scope and spirit of the invention are indicated by the claims.

[0057] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. An Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled, characterized in that: include: Ag wire (1), Parafilm sealing film (3), glass cannula (4), AgCl coating (5), KCl solution (6), porous plug (7); The Ag wire (1) is fixed in a glass sleeve (4) via a Parafilm sealing film (3); the glass sleeve (4) contains a KCl solution (6); the porous plug (7) is sintered to the end of the glass sleeve (4); the surface of the Ag wire in contact with the KCl solution is plated with an AgCl coating (5); and the upper part of the Ag wire (1) extends out of the tube mouth of the glass sleeve (4).

2. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: It also includes a rubber or silicone cap (2), which is placed outside the glass sleeve (4) and covered on the Parafilm sealing film (3), and one end of the Ag wire (1) passes through the rubber or silicone cap (2) and out of the tube mouth of the glass sleeve (4).

3. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: The AgCl coating on the surface of the Ag wire (1) is obtained by electroplating using a constant potential instrument.

4. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: The Ag wire (1) has a diameter of 0.8-1 mm and a length of 7-8 cm.

5. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: The porous plug (7) is one of a porous glass sand core, a ceramic core, and a porous polytetrafluoroethylene plug.

6. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: The volume of the KCl solution (6) is greater than the solubility of the glass sleeve, and the excess portion is concentrated in the form of droplets at the mouth of the glass sleeve.

7. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: The Parafilm sealing film (3) is tightly wrapped around the Ag wire (1) and the opening of the glass sleeve (4), thereby achieving the fixing of the Ag wire (1) in the glass sleeve through the Parafilm sealing film (3).

8. The Ag / AgCl reference electrode that is easy to disassemble and repair and can be recycled according to claim 1, characterized in that: The KCl solution (6) is a saturated potassium chloride solution.

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