Sensitive glass membrane for pure water pH electrode, pure water pH electrode and preparation method of pure water pH electrode

Abstract

The invention belongs to the technical field of chemical sensors, and particularly relates to a sensitive glass film for a pure water pH electrode, the pure water pH electrode and a preparation method of the pure water pH electrode. 1%-2% of Cs2O; 1% to 4% of La2O3; 3% to 5% of Ta2O5; 60%-70% of SiO2; the pure water pH electrode comprises a sensitive glass membrane, an Ag / AgCl internal reference electrode, an ion capture well and an Ag / AgCl external reference electrode, the Ag / AgCl internal reference electrode is filled with a mixed solution of neutral phosphate and potassium chloride, the Ag / AgCl external reference electrode is filled with gel electrolyte of saturated potassium chloride, and the ion capture well is filled with sulfonic acid type cation exchange resin. The accuracy and stability of pH electrode measurement can be effectively improved, and the pH measurement requirement of a pure water system of a nuclear power plant is met.

Description

Technical Field

[0001] This invention belongs to the field of chemical sensor technology, specifically relating to a sensitive glass membrane for a pure water pH electrode, the pure water pH electrode, and its preparation method. Background Technology

[0002] The Tianwan Nuclear Power Plant requires pH measurement of multiple steam-water systems to control their pH levels. Controlling the pH of these systems reduces metal corrosion rates, minimizes corrosion product deposition, and controls salt buildup in the turbines. Therefore, strictly controlling the pH of the steam-water systems is a crucial means of ensuring the safe and economical operation of the nuclear power unit.

[0003] However, current online pure water pH electrodes fail to meet the measurement accuracy and stability requirements of nuclear power plant pure water systems. The key reason for this lies in the unsuitable formulation of the sensitive glass membrane material used in these electrodes.

[0004] Therefore, there is an urgent need to develop a sensitive glass membrane and online pH electrode that meet the measurement requirements of pure water systems in nuclear power plants. Summary of the Invention

[0005] The purpose of this invention is to provide a sensitive glass membrane for a pure water pH electrode, a pure water pH electrode and its preparation method, which can effectively improve the accuracy and stability of pH electrode measurement and meet the pH measurement requirements of pure water systems in nuclear power plants.

[0006] Technical solution to achieve the purpose of this invention:

[0007] A sensitive glass membrane for a pH electrode in pure water, comprising the following components by mole fraction:

[0008] Li2O 24%–31%;

[0009] Cs₂O 1%–2%;

[0010] La2O3 1%–4%;

[0011] Ta2O5 3%–5%;

[0012] SiO2 60%–70%.

[0013] A pure water pH electrode includes: a sensitive glass membrane, a polytetrafluoroethylene ring, an Ag / AgCl internal reference electrode, an ion capture well, a conduit, an external reference gasket, an inner core glass tube, an Ag / AgCl external reference electrode, a glass support rod, and an S7 electrode connector.

[0014] The inner core glass tube is sealed at the bottom to a sensitive glass membrane. A glass support rod is fitted over the inner core glass tube, and a polytetrafluoroethylene ring is sealed between the bottom of the inner core glass tube and the bottom of the glass support rod. An outer reference glass tube is formed between the inner core glass tube and the glass support rod. An outer reference gasket is installed in the outer reference glass tube, and an ion trapping well is formed below the outer reference gasket. The ion trapping well is filled with sulfonic acid-type cation exchange resin. The outer reference glass tube above the outer reference gasket is filled with a saturated potassium chloride gel electrolyte. The inner core glass tube is filled with a neutral phosphate mixture containing potassium chloride. The outer reference gasket has a conduit. During measurement, chloride and potassium ions in the saturated potassium chloride gel electrolyte enter the ion trapping well through the conduit.

[0015] The Ag / AgCl end of the Ag / AgCl internal reference electrode is placed in the inner core glass tube, with the Ag / AgCl end suspended above the sensitive glass membrane. The Ag / AgCl end of the Ag / AgCl external reference electrode is placed in the outer reference glass tube, with the Ag / AgCl end suspended above the outer reference gasket. The top ends of the inner core glass tube and the glass support rod are respectively sealed with porous plastic soft plugs. The top end of the glass support rod is fixedly connected to the S7 electrode connector. The other ends of the Ag / AgCl internal reference electrode and the Ag / AgCl external reference electrode pass through the porous plastic soft plugs and are connected to the S7 electrode connector.

[0016] Furthermore, the sensitive glass membrane is hemispherical; the ion capture well height is 5-6 cm.

[0017] Furthermore, the potassium chloride concentration in the neutral phosphate mixed solution containing potassium chloride is 1.0 mol / L, the phosphate is an equimolar mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate, and the total phosphate concentration is 0.1 mol / L; the pH value of the mixed solution is 7.

[0018] Furthermore, the S7 electrode connector includes a copper alloy wire, a copper alloy sleeve, a polyethylene washer, and an insulating plastic sleeve; the inner ring of the polyethylene washer passes through and fixes the copper alloy wire, and the outer ring is fastened inside the copper alloy sleeve. The copper alloy wire and the copper alloy sleeve are respectively fixedly connected to the other end of the Ag / AgCl internal reference electrode and the Ag / AgCl external reference electrode; the copper alloy sleeve is connected to the top of the glass support rod; the insulating plastic sleeve is fitted on the copper alloy sleeve, and the S7 electrode connector is fixedly connected to the glass support rod through the copper alloy sleeve and the insulating plastic sleeve.

[0019] A method for preparing a pure water pH electrode, comprising:

[0020] Step 1: Prepare the sensitive glass film;

[0021] Step 2: Add ion capture wells;

[0022] Step 3: Assembly of Ag / AgCl internal reference electrode and Ag / AgCl external reference electrode;

[0023] Step 4: Assembly of the glass support rod and the S7 electrode connector.

[0024] Further, step 1 specifically involves: weighing the raw material components of the sensitive glass film, SiO2, Ta2O5, La2O3, Cs2O, and Li2CO3, according to the proportion, grinding and stirring them evenly, placing them in a platinum crucible, and then placing them in an electric furnace to melt and stir, removing air bubbles until the glass melt is completely clear; pouring the glass melt into a mold for annealing to obtain a sensitive glass rod, washing the sensitive glass rod with high-purity water and drying it to remove surface impurities; contacting the sensitive glass rod with the surface of the 1000℃ platinum crucible to melt the sensitive glass, and immediately removing the prepared inner core glass tube after contacting the molten sensitive glass, while gently blowing air into the inner core glass tube to ensure that the inner and outer surfaces of the hemispherical sensitive glass film fused to the end of the inner core glass tube are smooth, and measuring the resistance of the sensitive glass film to be between 200MΩ and 250MΩ to ensure that the quality of the sensitive glass film is qualified.

[0025] Further, step 2 specifically involves: inserting the inner ring of the polytetrafluoroethylene (PTFE) ring from the top to the bottom of the inner core glass tube on which the sensitive glass membrane is blown; then inserting the glass support rod into the outer ring of the PTFE ring; the inner and outer rings of the PTFE ring are tightly fitted together; an outer reference glass tube is formed between the inner core glass tube and the glass support rod; an outer reference gasket with a conduit is installed in the outer reference glass tube; an ion trapping well is formed at the bottom of the outer reference gasket; a polymer ion exchange resin is prepared; the ion trapping well is filled with polymer ion exchange resin; and the tube above the outer reference gasket of the outer reference glass tube is filled with a saturated potassium chloride gel electrolyte.

[0026] Further, step 3 specifically involves: preparing a neutral phosphate mixed solution containing potassium chloride, ensuring the pH value of the mixed solution is 7; filling the inner core glass tube with the neutral phosphate mixed solution containing potassium chloride; placing the Ag / AgCl end of the prepared Ag / AgCl internal reference electrode in the inner core glass tube, with the Ag / AgCl end suspended about 1 cm above the sensitive glass membrane; placing the Ag / AgCl end of the Ag / AgCl external reference electrode in the external reference glass tube, with the Ag / AgCl end suspended about 1 cm above the external reference gasket; passing the other ends of the Ag / AgCl internal and external reference electrodes through a porous plastic soft plug and inserting the porous plastic soft plug into the port; then sealing it with silicone; after the silicone solidifies, the Ag / AgCl internal and external reference electrodes are assembled.

[0027] Further, step 4 specifically involves: inserting and fixing the inner ring of the polyethylene gasket into the copper alloy wire, placing the outer ring inside the copper alloy sleeve and securing it therein, then covering the copper alloy sleeve with an insulating plastic sleeve. The copper alloy wire and the copper alloy sleeve serve as the connectors for the Ag / AgCl internal reference electrode and the Ag / AgCl external reference electrode, respectively. The copper alloy wire is fixedly connected to the silver wire of the Ag / AgCl internal reference electrode, and the silver wire of the Ag / AgCl external reference electrode is fixedly connected to the head of the copper alloy sleeve. Silicone is evenly coated on the inside and outside of the copper alloy sleeve and fitted onto the glass support rod. Then, the insulating plastic sleeve is fitted onto the copper alloy sleeve. After the silicone has completely hardened, the S7 electrode connector is completely fixed onto the glass support rod.

[0028] The beneficial technical effects of this invention are as follows:

[0029] 1. The sensitive glass membrane for pure water pH electrode provided by this invention has good glass properties and high stability.

[0030] 2. The pure water pH electrode provided by this invention can effectively improve the accuracy and stability of pH electrode measurement and meet the pH measurement requirements of pure water systems in nuclear power plants.

[0031] 3. The pure water pH electrode provided by this invention, by adding ion capture wells, not only slows down the rate of loss of saturated potassium chloride gel electrolyte reference solution, but also blocks the contamination of the reference electrode by heavy metal ions, improves the stability of the reference electrode, and extends the service life of the pH electrode. The service life of the pH electrode can reach more than 1 year, which meets the requirements of the pure water system of nuclear power plants for pH electrodes.

[0032] 4. The method for preparing a pure water pH electrode provided by the present invention can effectively reduce the preparation cost and usage cost of the pure water pH electrode.

[0033] 5. The pure water pH electrode provided by this invention can meet the online pure water pH measurement needs of other nuclear power plants, thermal power plants and chemical plants, and has good applicability. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a pure water pH electrode structure provided by the present invention.

[0035] In the figure: 1-Sensitive glass membrane; 2-PTFE ring; 3-Ag / AgCl internal reference electrode; 4-Ion capture well; 5-Conduit; 6-External reference gasket; 7-Inner core glass tube; 8-Ag / AgCl external reference electrode; 9-Glass support rod; 10-S7 electrode connector. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0037] This invention provides a sensitive glass membrane for a pure water pH electrode. In the sensitive glass membrane composition, Li₂O and SiO₂ are essential components. SiO₂ is the framework material of the sensitive glass, and its molar content cannot be less than 60%; otherwise, the produced glass will be difficult to achieve a non-crystallizing effect. Li₂O contains Li... + It is related to H in the sample water + The key ions involved in the exchange process are Cs₂O and Li₂O. The addition of Li₂O can reduce the alkalinity error of the electrode. However, when the molar content of Li₂O reaches 31% or more, the resistance of the glass electrode increases significantly, and other properties also decrease. Introducing a small amount of Cs₂O can address the increase in resistance and improve the chemical stability of the glass.

[0038] Introducing La2O3 into sensitive glass reduces the coefficient of thermal expansion, increases the softening temperature, and enhances water resistance. It also improves the crystallization properties of the glass, narrowing the crystallization temperature range and shifting it towards the lower temperature range, making the glass easier to process and shape. The glass performance is best when the molar content of La2O3 is controlled between 1% and 4%.

[0039] The introduction of a small amount of Ta2O5 can significantly improve electrical conductivity and further narrow the crystallization temperature range, but it will have the opposite effect when the molar content is greater than 5%.

[0040] Therefore, the sensitive glass film material was selected as the Li2O-Cs2O-La2O3-Ta2O5-SiO2 system.

[0041] This invention provides a sensitive glass membrane for a pH electrode in pure water, which is composed of the following components by mole fraction:

[0042] Li2O 24%–31%;

[0043] Cs₂O 1%–2%;

[0044] La2O3 1%–4%;

[0045] Ta2O5 3%–5%;

[0046] SiO2 60%–70%.

[0047] Example 1

[0048] The sensitive glass membrane used in the pure water pH electrode in this embodiment is composed of the following components, by mole fraction:

[0049] Li2O 25%;

[0050] Cs2O 1.5%;

[0051] La2O3 2.5%;

[0052] Ta2O5 4%;

[0053] SiO2 67%.

[0054] Example 2

[0055] The sensitive glass membrane used in the pure water pH electrode in this embodiment is composed of the following components, by mole fraction:

[0056] Li2O 24%;

[0057] Cs₂O 2%;

[0058] La2O3 4%;

[0059] Ta2O5 5%;

[0060] SiO2 65%.

[0061] Example 3

[0062] The sensitive glass membrane used in the pure water pH electrode in this embodiment is composed of the following components, by mole fraction:

[0063] Li2O 31%;

[0064] Cs₂O 1%;

[0065] La2O3 1%;

[0066] Ta2O5 3%;

[0067] SiO2 64%.

[0068] like Figure 1 As shown, the present invention provides a pure water pH electrode, comprising: a sensitive glass membrane 1, a polytetrafluoroethylene ring 2, an Ag / AgCl internal reference electrode 3, an ion trapping well 4, a conduit 5, an external reference gasket 6, an inner core glass tube 7, an Ag / AgCl external reference electrode 8, a glass support rod 9, and an S7 electrode connector 10; wherein, the Ag / AgCl internal reference electrode 3 is filled with a mixed solution of neutral phosphate and potassium chloride, the Ag / AgCl external reference electrode 8 is filled with a saturated potassium chloride gel electrolyte, and the ion trapping well 4 is filled with a polymer ion exchange resin.

[0069] The inner core glass tube 7 is sealed at its bottom end to the sensitive glass membrane 1, forming an integral structure. The sensitive glass membrane 1 is hemispherical. A polytetrafluoroethylene (PTFE) ring 2 is fitted at the bottom end of the inner core glass tube 7. A glass support rod 9 is fitted outside the inner core glass tube 7. The PTFE ring 2 is located between the inner core glass tube 7 and the glass support rod 9. The inner and outer rings of the PTFE ring 2 are tightly fitted to the inner core glass tube 7 and the glass support rod 9, respectively, forming a sealed connection. An outer reference glass tube is formed between the inner core glass tube 7 and the glass support rod 9. An outer reference gasket 6 is installed in the outer reference glass tube. An ion trapping well 4 is formed below the outer reference gasket 6, with a height of approximately 5-6 cm. The ion trapping well 4 is filled with sulfonic acid-type cation exchange resin. The outer reference glass tube, located above the outer reference gasket 6, is filled with a saturated potassium chloride gel electrolyte, i.e., a semi-solid solution formed by adding agar as a gelling agent to a saturated potassium chloride solution. The external reference gasket 6 has a conduit 5. During measurement, chloride and potassium ions from the saturated potassium chloride gel electrolyte enter the ion trapping well 4 through the conduit 5, and then permeate into the sample water through the polytetrafluoroethylene ring 2. The inner core glass tube 7 is filled with a neutral phosphate mixture containing potassium chloride. The potassium chloride concentration in the neutral phosphate mixture is 1.0 mol / L, and the phosphate is an equimolar mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate, with a total phosphate concentration of 0.1 mol / L. The pH of the mixture is adjusted to 7.

[0070] The Ag / AgCl end of the Ag / AgCl internal reference electrode 3 is placed in the inner core glass tube 7, and the Ag / AgCl end is suspended about 1 cm above the sensitive glass membrane 1. The Ag / AgCl end of the Ag / AgCl external reference electrode 8 is placed in the external reference glass tube, and the Ag / AgCl end is suspended about 1 cm above the external reference gasket 6. The top ends of the inner core glass tube 7 and the glass support rod 9 are respectively sealed with porous plastic soft plugs. The top end of the glass support rod 9 is fixedly connected to the S7 electrode connector 10. The other ends of the Ag / AgCl internal reference electrode 3 and the Ag / AgCl external reference electrode 8 pass through the porous plastic soft plugs and are connected to the S7 electrode connector 10.

[0071] The S7 electrode connector 10 includes a copper alloy wire, a copper alloy sleeve, a polyethylene washer, and an insulating plastic sleeve. The inner ring of the polyethylene washer passes through and fixes the copper alloy wire, while the outer ring is fastened inside the copper alloy sleeve. The copper alloy wire and the copper alloy sleeve are respectively fixedly connected to the other end of the Ag / AgCl internal reference electrode 3 and the Ag / AgCl external reference electrode 8. The copper alloy sleeve is connected to the top of the glass support rod 9, and the insulating plastic sleeve is fitted onto the copper alloy sleeve. The S7 electrode connector 10 is fixedly connected to the glass support rod 9 through the copper alloy sleeve and the insulating plastic sleeve.

[0072] This invention discloses a pure water pH electrode. By adding an ion-capturing well filled with a high-molecular-weight ion-extraction resin within an external reference glass tube, this polymeric material slows the loss of saturated potassium chloride gel electrolyte and absorbs excess heavy metal ions from the reference structure, preventing poisoning of the external reference electrode. Verification has shown that the pH electrode made with the sensitive glass membrane formulation combined with the ion-capturing well further increases the accuracy and stability of pH measurements, meeting the pH measurement requirements of pure water systems in nuclear power plants.

[0073] This invention provides a method for preparing a pure water pH electrode, specifically including the following steps:

[0074] Step 1: Making the sensitive glass film 1

[0075] The raw materials used are analytical grade SiO2, Ta2O5, La2O3, and Cs2O reagents, with analytical grade Li2CO3 introduced into Li2O. The required amounts of raw materials are weighed according to the formula ratio, ground finely and stirred evenly in an agate mortar, and then placed in a platinum crucible. The crucible is then melted and stirred in an electric furnace to remove air bubbles until the glass melt is completely clear. The glass melt is poured into a mold and annealed at 500℃ for 2 hours to obtain a sensitive glass rod. The sensitive glass rod is washed with high-purity water and dried at 120℃ for 2 hours to remove surface impurities. The sensitive glass rod is brought into contact with the surface of the 1000℃ platinum crucible to melt the sensitive glass. The end of the prepared inner core glass tube 7 is brought into contact with the molten sensitive glass and then immediately removed. At the same time, air is gently blown into the inner core glass tube 7 to ensure that the inner and outer surfaces of the hemispherical sensitive glass film 1 fused to the end of the inner core glass tube 7 are smooth. The outer diameter of the blown sensitive glass film 1 is about 8mm. The resistance of the sensitive glass film 1 is measured to be between 200MΩ and 250MΩ to ensure that the quality of the sensitive glass film 1 is qualified.

[0076] Step 2: Add ion capture well 4

[0077] The inner ring of the polytetrafluoroethylene (PTFE) ring 2 is inserted from the top to the bottom of the inner core glass tube 7, on which the sensitive glass membrane 1 is blown. The glass support rod 9 is then inserted into the outer ring of the PTFE ring 2, ensuring that the glass support rod 9 completely encloses the PTFE ring 2, guaranteeing a tight fit between the inner and outer rings without loosening. An outer reference glass tube is formed between the inner core glass tube 7 and the glass support rod 9. An outer reference gasket 6 with a conduit 5 is inserted into the outer reference glass tube. An ion-capturing well 4 is formed at the bottom of the outer reference gasket 6, with a height of approximately 5-6 cm. A sulfonic acid-type cation exchange resin is prepared, and the ion-capturing well 4 is filled with a polymeric ion exchange resin. The outer reference glass tube, located above the outer reference gasket 6, is filled with a saturated potassium chloride gel electrolyte, i.e., a semi-solid solution of saturated potassium chloride with added gelling agent agar. The external reference gasket 6 separates the polymer ion exchange resin from the saturated potassium chloride gel electrolyte, preventing the polymer ion exchange resin from mixing with the saturated potassium chloride gel electrolyte. During measurement, chloride ions and potassium ions in the gel electrolyte enter the ion capture well 4 through the conduit 5, and then permeate into the sample water through the polytetrafluoroethylene ring 2.

[0078] Step 3: Assembly of Ag / AgCl internal reference electrode 3 and Ag / AgCl external reference electrode 8

[0079] Prepare a neutral phosphate mixture containing potassium chloride. The potassium chloride concentration in the mixture is 1.0 mol / L, and the phosphate is an equimolar mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate, with a total phosphate concentration of 0.1 mol / L. Ensure the pH of the mixture is 7. Pour the potassium chloride-containing neutral phosphate mixture into the inner glass tube 7, and fill the upper part of the ion trapping well 4 with a saturated potassium chloride gel electrolyte. The Ag / AgCl end of the fabricated Ag / AgCl internal reference electrode 3 is placed in the inner core glass tube 7, with the Ag / AgCl end suspended about 1 cm above the sensitive glass membrane 1. The Ag / AgCl end of the Ag / AgCl external reference electrode 8 is placed in the external reference glass tube, with the Ag / AgCl end suspended about 1 cm above the external reference gasket 6. The other ends of the Ag / AgCl internal reference electrode 3 and the Ag / AgCl external reference electrode 8 are passed through a porous plastic soft plug and the porous plastic soft plug is inserted into the port. Then, silicone is used for sealing. After the silicone solidifies, the Ag / AgCl internal reference electrode 3 and the Ag / AgCl external reference electrode 8 are assembled.

[0080] Step 4: Assembly of glass support rod 9 and S7 electrode connector 10

[0081] The S7 electrode connector 10 mainly consists of the following parts: a copper alloy wire, a copper alloy sleeve, a polyethylene gasket, and an insulating plastic sleeve. The copper alloy wire can be inserted and fixed in the middle of the polyethylene gasket, and its outer ring fits perfectly inside the copper alloy sleeve and is securely fastened therein. The insulating plastic sleeve is then placed over the copper alloy sleeve. The copper alloy wire and the copper alloy sleeve serve as the connecting bodies for the Ag / AgCl internal reference electrode 3 and the Ag / AgCl external reference electrode 8, respectively, and are separated by the polyethylene gasket to prevent contact between the copper alloy wire and the copper alloy sleeve. A small amount of solder is applied to the copper alloy wire and the silver wire of the Ag / AgCl internal reference electrode 3 in the S7 electrode connector 10, and they are soldered together with a soldering iron. The silver wire of the Ag / AgCl external reference electrode 8 is soldered to the head of the copper alloy sleeve. The solder joint is cleaned with anhydrous ethanol to remove flux residue, and excess copper alloy wire and electrode silver wire are trimmed from the solder joint. Apply silicone evenly to the inside and outside of the copper alloy sleeve and then put it on the glass support rod 9. Then put the insulating plastic sleeve on the copper alloy sleeve. After the silicone has completely hardened, the S7 electrode connector 10 is completely fixed on the glass support rod 9.

[0082] At this point, the online pH electrode for pure water has been successfully fabricated.

[0083] The accuracy and stability of the pure water pH electrode prepared using the present invention were tested, and the test results are shown in Tables 1 and 2.

[0084] Table 1. Measurement accuracy results (pH value) of pH electrode in pure water.

[0085] Measuring solution Measured value Measurement error Indicated value tolerance in conclusion 4.00 4.01 0.01 ±0.03 qualified 7.00 7.00 0.00 ±0.03 qualified 9.00 9.02 0.02 ±0.03 qualified

[0086] Table 2. Measurement stability results (pH value) of the pH electrode in pure water.

[0087] Measuring solution Repeatability Repeatability tolerance in conclusion 4.00 0.009 ±0.02 qualified 7.00 0.009 ±0.02 qualified 9.00 0.007 ±0.02 qualified

[0088] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. All contents not described in detail in the present invention can be derived from existing technologies.

Claims

1. A sensitive glass membrane for a pure water pH electrode, characterized in that, It consists of the following components in mole fraction: Li2O 24%–31%; Cs₂O 1%–2%; La2O3 1%–4%; Ta2O5 3%–5%; SiO2 60%–70%.

2. A pure water pH electrode, characterized in that, include: Sensitive glass membrane (1), polytetrafluoroethylene ring (2), Ag / AgCl internal reference electrode (3), ion capture well (4), conduit (5), external reference gasket (6), inner core glass tube (7), Ag / AgCl external reference electrode (8), glass support rod (9), S7 electrode connector (10); the sensitive glass membrane (1) is the sensitive glass membrane for pure water pH electrode as described in claim 1; The bottom end of the inner core glass tube (7) is sealed to the sensitive glass membrane (1). The glass support rod (9) is sleeved on the outside of the inner core glass tube (7). A polytetrafluoroethylene ring (2) is sealed between the bottom end of the inner core glass tube (7) and the bottom end of the glass support rod (9). An outer reference glass tube is formed between the inner core glass tube (7) and the glass support rod (9). An outer reference gasket (6) is installed in the outer reference glass tube. An ion trapping well (4) is formed at the bottom of the outer reference gasket (6). The ion trapping well (4) is filled with sulfonic acid cation exchange resin. The tube above the outer reference gasket (6) is filled with saturated potassium chloride gel electrolyte. The inner core glass tube (7) is filled with a neutral phosphate mixed solution containing potassium chloride. The outer reference gasket (6) is equipped with a conduit (5). During measurement, chloride ions and potassium ions in the saturated potassium chloride gel electrolyte enter the ion trapping well (4) through the conduit (5). The Ag / AgCl end of the Ag / AgCl internal reference electrode (3) is placed in the inner core glass tube (7), and the Ag / AgCl end is suspended above the sensitive glass membrane (1); the Ag / AgCl end of the Ag / AgCl external reference electrode (8) is placed in the external reference glass tube, and the Ag / AgCl end is suspended above the external reference gasket (6); the top ends of the inner core glass tube (7) and the glass support rod (9) are respectively sealed with porous plastic soft plugs, and the top end of the glass support rod (9) is fixedly connected to the S7 electrode connector (10); the other ends of the Ag / AgCl internal reference electrode (3) and the Ag / AgCl external reference electrode (8) pass through the porous plastic soft plugs and are connected to the S7 electrode connector (10).

3. The pure water pH electrode according to claim 2, characterized in that, The sensitive glass membrane (1) is hemispherical; the ion capture well (4) has a height of 5-6 cm.

4. A pure water pH electrode according to claim 2, characterized in that, The potassium chloride-containing neutral phosphate mixed solution has a potassium chloride concentration of 1.0 mol / L, and the phosphate is an equimolar mixture of potassium dihydrogen phosphate and disodium hydrogen phosphate, with a total phosphate concentration of 0.1 mol / L; the pH of the mixed solution is 7.

5. A pure water pH electrode according to claim 2, characterized in that, The S7 electrode connector (10) includes a copper alloy wire, a copper alloy sleeve, a polyethylene washer, and an insulating plastic sleeve. The inner ring of the polyethylene washer is inserted into and fixes the copper alloy wire, and the outer ring is fastened inside the copper alloy sleeve. The copper alloy wire and the copper alloy sleeve are respectively fixedly connected to the other end of the Ag / AgCl internal reference electrode (3) and the Ag / AgCl external reference electrode (8). The copper alloy sleeve is connected to the top of the glass support rod (9). The insulating plastic sleeve is fitted on the copper alloy sleeve, and the S7 electrode connector (10) is fixedly connected to the glass support rod (9) through the copper alloy sleeve and the insulating plastic sleeve.

6. A method for preparing a pure water pH electrode, used to prepare the pure water pH electrode according to any one of claims 2-5, characterized in that, include: Step 1: Prepare the sensitive glass film (1); Step 2: Add ion capture well (4); Step 3: Assembly of Ag / AgCl internal reference electrode (3) and Ag / AgCl external reference electrode (8); Step 4: Assembly of the glass support rod (9) and the S7 electrode connector (10).

7. The method for preparing a pure water pH electrode according to claim 6, characterized in that, Step 1 specifically involves: weighing the raw material components of the sensitive glass film, SiO2, Ta2O5, La2O3, Cs2O, and Li2CO3, according to the proportions, grinding them finely and stirring them evenly, placing them in a platinum crucible, and then placing them in an electric furnace to melt and stir, removing air bubbles until the glass melt is completely clear; pouring the glass melt into a mold and annealing it to obtain a sensitive glass rod, washing the sensitive glass rod with high-purity water and drying it to remove surface impurities; Contact the surface of the 1000℃ platinum crucible with a sensitive glass rod to melt the sensitive glass. Immediately after contacting the end of the prepared inner core glass tube (7) with the molten sensitive glass, gently blow air into the inner core glass tube (7) to ensure that the inner and outer surfaces of the hemispherical sensitive glass film (1) fused to the end of the inner core glass tube (7) are smooth. Measure the resistance of the sensitive glass film (1) to be between 200MΩ and 250MΩ to ensure that the sensitive glass film (1) is of qualified quality.

8. The method for preparing a pure water pH electrode according to claim 6, characterized in that, Step 2 specifically involves: inserting the inner ring of the polytetrafluoroethylene ring (2) from the top to the bottom of the inner core glass tube (7) with the blown sensitive glass membrane (1), and then inserting the glass support rod (9) into the outer ring of the polytetrafluoroethylene ring (2), and tightening the inner and outer rings of the polytetrafluoroethylene ring (2); forming an outer reference glass tube between the inner core glass tube (7) and the glass support rod (9), inserting an outer reference gasket (6) with a conduit (5) into the outer reference glass tube, and forming an ion trapping well (4) at the bottom of the outer reference gasket (6); preparing a polymer ion exchange resin, filling the ion trapping well (4) with polymer ion exchange resin, and filling the tube above the outer reference gasket (6) with a saturated potassium chloride gel electrolyte.

9. The method for preparing a pure water pH electrode according to claim 6, characterized in that, Step 3 specifically involves: preparing a neutral phosphate mixed solution containing potassium chloride, ensuring the pH value of the mixed solution is 7; filling the neutral phosphate mixed solution containing potassium chloride into the inner core glass tube (7); placing the Ag / AgCl end of the prepared Ag / AgCl internal reference electrode (3) in the inner core glass tube (7), with the Ag / AgCl end suspended about 1 cm above the sensitive glass membrane (1); placing the Ag / AgCl end of the Ag / AgCl external reference electrode (8) in the external reference glass tube, with the Ag / AgCl end suspended about 1 cm above the external reference gasket (6); passing the other ends of the Ag / AgCl internal reference electrode (3) and the Ag / AgCl external reference electrode (8) through a porous plastic soft plug and inserting the porous plastic soft plug into the port; then sealing with silicone; and completing the assembly of the Ag / AgCl internal reference electrode (3) and the Ag / AgCl external reference electrode (8) after the silicone solidifies.

10. The method for preparing a pure water pH electrode according to claim 6, characterized in that, Step 4 specifically involves: inserting and fixing the inner ring of the polyethylene gasket into the copper alloy wire, placing the outer ring inside the copper alloy sleeve and securing it within the copper alloy sleeve, then covering the copper alloy sleeve with an insulating plastic sleeve. The copper alloy wire and the copper alloy sleeve serve as the connectors for the Ag / AgCl internal reference electrode (3) and the Ag / AgCl external reference electrode (8), respectively. The copper alloy wire is fixedly connected to the silver wire of the Ag / AgCl internal reference electrode (3), and the silver wire of the Ag / AgCl external reference electrode (8) is fixedly connected to the head of the copper alloy sleeve. Silicone is evenly coated on the inside and outside of the copper alloy sleeve and fitted onto the glass support rod (9). The insulating plastic sleeve is then fitted onto the copper alloy sleeve. After the silicone has completely hardened, the S7 electrode connector (10) is completely fixed onto the glass support rod (9).

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