JPS59154351A - Hydrogen ion concentration measuring apparatus - Google Patents

Abstract

PURPOSE:To use a titled apparatus under high temp. and pressure by providing an indicator electrode for measuring a hydrogen concn. having constitution wherein an internal electrode and an internal electrolyte are contained in a vessel which is formed of an H<+>-sensitive glass or an oxygen ion-conductive solid electrolyte, and using a specified metallic composite for a reference electrode. CONSTITUTION:In the hydrogen ion concn. measuring apparatus, an indicator electrode 10 is a hollow body of a hydrogen ion-sensitive membrane 10A, and is made of a hydrogen ion-sensitive glass membrane or stabilized zirconia. An internal electrode 11 of silver coated with silver chloride or the like and an electrolyte 12 such as a KCl soln. etc. are packed in the hollow sensitive membrane body 10A. Whereas, a reference electrode 20 is constituted of silver or silver alloy or a metallic composite 20 coated with silver (alloy) on the surface, and is covered with an insulating film 21. Since the electrodes 10 and 20 are constituted to resist high temp. and pressure, the direct pH measurement of an aq. soln. such as the primary cooling water or the boiler water in a nuclear power plant at high temp. and pressure can be made possible.

Description

[Detailed description of the invention]

The present invention relates to an apparatus for measuring hydrogen ion concentration in an aqueous solution. For more details, see 1. Il of aqueous solution under high temperature and high pressure conditions
There are 1-related devices for measuring H value, including sensors for measuring hydrogen ion concentration in aqueous solutions, PL-1 measurement for water quality control of various industrial waters, and direct measurement under high temperature and high pressure conditions. The present invention provides a hydrogen ion concentration measuring device for use. Conventionally, the concentration of hydrogen ions in an aqueous solution is measured by inserting a hydrogen ion selective electrode and a reference electrode into the measurement solution along with an indicator electrode. FIG. 1 shows an outline of a conventional measuring device. 1 is an indicator electrode, and a hydrogen ion selective electrode is used. A reference electrode 2 houses an internal electrode 3 and an internal electrolyte 4, and has a liquid junction 5. 6 is a potential difference if. 7 is a measurement liquid. Conventionally, a glass electrode has been used as a hydrogen ion selective electrode. As is well known, the structure of the glass electrode is that it has a glass-sensitive membrane that is sensitive to hydrogen ion concentration, is filled with an electrolyte internal solution having a known hydrogen ion concentration, and has an internal electrode in contact with this internal electrolyte solution. A potential difference is generated between the inner and outer surfaces of the glass membrane according to the equation for Nerns 1, depending on the hydrogen ion activity concentration in the external measurement liquid. In order to fully demonstrate its characteristics, this glass electrode is manufactured using a glass hydrogen ion sensitive membrane that is extremely thin, homogeneous, and has no defects or distortions inside the membrane. Depending on the liquid properties of the aqueous solution, it may be corroded, resulting in deterioration such as a decrease in the battery output of -C as a sensitive membrane.In addition, especially when the measurement liquid is at a high temperature, the glass membrane may deteriorate. is further promoted, and it is hard to withstand thermal shock, so in effect,
The liquid temperature used here is at most 110-130°C. On the other hand, as the comparison electrode 2, a force[]mel electrode, a silver-chloride 8I2 electrode, or the like is generally used. For example, a silver-silver chloride electrode is a well-known method in which a container 2a made of glass or the like is filled with an electrolyte salt solution 4, and an internal electrode 3 made of silver coated with silver chloride is immersed in the container 2a. A chemical half cell is formed, and a so-called liquid junction 5 is provided in a part of the container 2a.
have. Ion diffusion and conduction are achieved between the liquid to be measured 7 and the internal electrolyte 4 of the comparison electrode 2 via the liquid junction 5. Due to the technical configuration described above, it inherently has the following drawbacks in actual measurements. 1. Ions of the internal electrolyte 4 leak into the measurement liquid via the liquid junction 5. Because of this, the liquid to be measured 7 may be contaminated or the true ion concentration may not be measured. 2. The internal electrolyte 8!24 may decrease or its concentration may change due to leakage from the liquid junction 5, which may cause the original reference potential of the reference electrode to fluctuate and become -C. In addition, the liquid junction 5 may be blocked by 3° or 1φ, and in this case, the above-mentioned electrical continuity cannot be achieved for 1H, and the measurement must be done in-house. 4. In order to obtain smooth electrical conduction at the liquid junction 5, the internal liquid 4
It is necessary that the pressure condition is at least more positive than that of the liquid to be measured 7. To address the drawbacks of J's 10, we have tried to reduce leakage as much as possible by making the structure of the liquid junction finer, making the electrolyte gel, and preventing deterioration and depletion of the internal electrolyte. Various methods are being used, including reconsidering the equipment that pressurizes the liquid. However, the above-mentioned drawbacks cannot be overcome with the conventional technology in which a liquid junction is formed with an electrolyte inside to stabilize the potential as a reference electrode. As explained above, in conventional measurement methods and techniques, when the measuring liquid is under high temperature and high pressure conditions such as primary cooling water in nuclear power plants, boiler water, chemical plants, etc. The reference electrodes that can be used here are not only unsatisfactory because troubles occur particularly at the liquid junction, but also the measurement of ρ1-1 itself is extremely cumbersome. Recently, a new hydrogen ion concentration method has been proposed for this technology, which uses one step for oxygen ion conduction. U.S. Patent No. 4,264,424 Mei II
According to Publication No. 77751), a method is shown in which a diaphragm made of a special ceramic is used instead of a glass membrane and the potential difference generated between the two sides of the diaphragm is measured. Due to the extremely large potential difference, the generated potential difference is unstable and the measurement becomes unreliable. In addition, to perform this measurement, a conventional electrode with a liquid junction structure is used as a reference electrode. There is. Therefore, the above-mentioned drawbacks still remain. An object of the present invention is to provide a new hydrogen ion concentration measuring device which overcomes the drawbacks of the conventional hydrogen ion concentration measuring techniques as described above. The first purpose is to be able to directly measure high-temperature measurement liquids. The second purpose is to be able to directly measure high-pressure measurement liquids. The third purpose is to have no internal electrolyte as a reference electrode. The fourth target is the so-called liquid junction structure. The fifth purpose is that it can be set up extremely simply, and its handling is simple and easy.

[ru. In the present invention, an indicator electrode for measuring hydrogen ions having a terminal connected to one electrode terminal of a measuring device and a metal electrode body having a terminal connected to the other electrode terminal are directly immersed in an aqueous solution. In a device that measures the hydrogen ion concentration in an aqueous solution by measuring the potential difference generated between both terminals, the indicator electrode for hydrogen ion measurement consists of a container with a closed end and an internal electrode inside the container. The closed end is formed of at least hydrogen ion-sensitive glass or oxygen ion conductive solid electrolyte, and the surface of the metal electrode body that comes into contact with the aqueous solution is made of silver, silver alloy, or silver, This is a device for measuring the degree of hydrogen ion fA using an oxide of a silver alloy or a laminate thereof.The oxygen ion conductive solid electrolyte used in the present invention is preferably stabilized Zir-Jnia.The metal electrode body is made of silver, Silver alloys or silver or silver alloys coated with the oxide of (A) (Aluminum, niracles, copper, iron, etc., coated with silver or silver alloys plated or laminated), or The outer surface of the metal electrode body may be coated with an oxide of silver or silver alloy with corrugations.Also, the metal electrode body should have at least a part of the liquid immersion part covered with an insulator, and its base should be attached to the insulator. Any material that can be used to measure the quantity to be measured may be used. The structure of the present invention will be explained in more detail. The structure of the present invention that prevents the ionic electrolyte from leaking into the liquid is shown in dimensions.In d3 in Fig. 2, 10 is an indicator electrode, 20 is a metal electrode body, and both are immersed (in contact) in the measuring liquid 15. The indicator electrode 10 has a hollow body structure with a hydrogen ion sensitive membrane 10A made of a solid electrolyte.The solid electrolyte is a hydrogen ion sensitive glass membrane or a stable Ividyl membrane.
Selected by Nia. Inside this hollow body, an internal electrode 11 and an internal electrolyte 12 are provided.
is filled. The internal electrode 11 is often made of silver coated with silver chloride, but other metals may also be used. For the internal electrolyte 12, a salt solution such as a potassium chloride solution is used, for example. Also, mixtures of metals and other metals with metal oxides-C
Fabricated solid electrolytes are also used. The indicator electrode 10 configured in this manner has a terminal 13 for taking out the electric wire. This terminal 13 is the internal electrode 1
1 and is electrically connected. Further, it is desirable that the inner and outer ends of the hollow body be sealed off and sealed by adhesive or other means. The metal electrode body 20 is selected from silver, a silver alloy, or a metal whose surface is coated with an oxide of silver and a silver alloy. This metal electrode body 20 has a part or all of its surface exposed, and has an insulating coating part 21 and an insulating part 22. The insulating portion 22 may constitute a mounting member that is attached to the measurement container 16. Furthermore, it has a terminal 23 for taking out an electric signal, and this terminal 23 is electrically connected to the metal electrode body 20. The voltage difference generated between the indicator electrode 10 and the metal electrode body 20 is measured at a voltage of 812 G via an intensifier 25 connected to one terminal 13 and the other terminal 23. The indicator electrode 10 has an internal resistance of 6, so the increase +j
] The device 25 has a high input resistance I5, and the lead wires from the respective terminals 13 and 23 are shielded 1/1 and 24 to prevent ingress of electromagnetic noise. The hollow body constituting the indicator electrode 10 is made of stabilized Zirnia porcelain, the internal electrolyte 12 is made of potassium chloride solution, the internal electrode 11 is made of silver coated with silver chloride (Δa(1)),
The operation of the indicator electrode 10 and the metal electrode body 20 of the present invention, which are constructed using silver as the metal electrode body 20, is immersed in an aqueous solution as a measuring liquid. An electrochemical unipolar potential is generated at the internal electrode 11 in contact with the internal electrolyte 12. On the inner and outer surfaces of the sensitive membrane portion 10A of the indicator electrode 10, electrochemical void cells are generated at the respective membrane interfaces. This generated potential is defined by the balance of ionic species at each interface. The potential on the inner surface of the crotch 10Δ becomes constant when the hydrogen ion concentration of the internal electrolyte is determined. The potential of the outer surface of the crotch 10 A is that the active hot stones of the ionic species in the measurement solution 15 are balanced on this membrane surface, so if we now focus on the ionic species as hydrogen ions, we can see that the potential is A potential is generated according to the Nerns equation depending on the activity concentration of hydrogen ions. In general, the activity concentration of hydrogen ions in the aqueous solution of the box material is proportional to the hydrogen ion concentration, so the inner and outer surfaces of the sensitive membrane 10△ follow the Nernst equation, which is proportional to the logarithm of the hydrogen ion concentration in the measurement solution. A potential difference occurs. Also, a half-cell corresponding to the activity of the ionic species in the aqueous solution is formed on the surface of the metal electrode 20 located a3 near the sensitive membrane 10Δ, and a unipolar potential is generated in this electrode 20. Therefore,
The device configured in this way can be seen as one battery as a whole. The potential difference measured by the device is proportional to the logarithm of the hydrogen ion concentration in the measurement solution. We have developed an electrode body.In this case, the metal electrode body can be made of metal whose surface is coated with silver, silver alloys, or oxides of silver or silver alloys, or silver or silver alloys on metal bases such as copper, aluminum, nickel, and iron. When used by attaching appropriate fixtures to the indicator electrode and metal electrode body of the present invention described above, the measuring device of the present invention has the following advantages over the prior art: We provide a completely new hydrogen ion concentration measurement device that does not leak the internal electrolyte of the reference electrode into the measurement liquid. ■ Has no liquid junction structure. ■ The liquid in contact with it is made of a physically stable solid. In addition, in Figure 3, the same reference numerals as in Figure 2 indicate the same or similar components. Embodiment (1) In the configuration of the present invention shown in FIG.
It is a ceramic having a closed structure at one end of stabilized Zirninia containing 1 to 85 moles of ittria. The outer diameter is 8 mmφ, the inner diameter is 5 mmφ, the length is 150 mm, and the wall thickness of the 1315 end is 45 mm. 20 is a metal electrode body, which is a silver wire with a thickness of 1 mmφ, approximately 2
0mm is exposed and the area is covered with ceramic coating. Inside the indicator electrode 10, an internal electrolyte 12 and an internal electrode 1 are provided.
1 is stored. The internal electrolyte 12 is 37 l/β of 1 <CI! , in aqueous solution,
Internal type tfi11 is A! ;l It is a silver wire coated with Cu2/ζ with a thickness of 1 mmφ. FIG. 3 shows the configuration of an experimental device for evaluating the performance of the measuring device of the present invention. In Figure 3, test tank 3
0 is made of SUS, has an internal volume of approximately 18℃, and has a measuring liquid of 15
Contains approximately 13ρ of pure water. This test chamber ζ30 contains an indicator 8i10 and a metal electrode body 2.
0 into the measuring solution 15).
The electrode terminals of both electrodes 10 and 20 were respectively connected to an intensifier 25 having a high input resistance by a Teflon-coated coaxial couple, and the output of the intensifier 25 was measured by a pen recorder. The indicator electrode 10 is generally an IC amplifier 11 having a high internal resistance.The amplifier 25 has a high input resistance circuit.The lead wire connecting the indicator electrode 10 and the amplifier 25 is provided with a shield 37. Further, the lead wire connecting the metal electrode body 20 and the amplifier 11] is also provided with a C' shield 37 for the purpose of preventing infiltration of electromagnetic induction noise. The chemical liquid tanks 40, 41, and 42 are used to change the ion concentration in the aqueous solution of the measurement liquid. For example, the chemical liquid tank 40 is filled with an acidic aqueous solution, the chemical liquid tank 41 is filled with a neutral liquid, and the chemical liquid tank 42 is filled with a predetermined chemical liquid such as an alkaline aqueous solution. 39 is a switching branch, and 38 is a chemical liquid introduction part.By operating the switching branch 39, any chemical liquid can be introduced into the measurement liquid. Furthermore, it has the following functions and equipment to perform measurements under high temperature and high pressure conditions. 43 is a heating section, 44
Reference numeral 45 indicates a temperature sensor, and numeral 45 indicates a heating device to heat and control the temperature of the liquid to be measured.A pressure device 47 that can feed the liquid under pressure is arranged in the chemical solution introduction section 38, and a pressure device 47 for detecting the internal pressure of the test chamber 30 A total of 46 are numbered f. Since the test chamber 30 constitutes a pressurized container, the members (indicator electrode 10, metal electrode body 20, pressure 146, temperature 144, and chemical solution introduction part 38) that are attached to it are attached to the mounting interface. It is firmly attached with a sealing function that can withstand these pressures. In the experiment, we measured and recorded the potential difference between both electrodes when an appropriate amount of acid or alkaline solution from the chemical tank 40, 41, 42 tank was poured into the measuring liquid and the 01-1 value of the measuring liquid was changed. Figure 4 (shown here). At this point, the water temperature was set to 95°C and rolled for 1 to 1 hour. The potential difference at this time showed +-95 mV. Next, an acid solution was added to this measurement solution, and the measurement solution was The pH value of
4, the generated potential difference between both electrodes is 4-340+
11V, and then add an alkaline solution to 1 of the measurement solution.
] (When the value is 118, the potential difference is -163 mV
, and add +12 acid solution again to adjust the l) l- of the measurement solution.
The potential difference when the 1 value becomes 23 is -j-34/l m
It showed V. In addition, a stable potential difference was obtained, reaching a saturation value in a short time with respect to changes in p t - (of the measuring solution).Example (2) Assemble a measurement system with the same configuration as above using a 1 mmφ silver alloy with silver: copper = 9: 1. The potential difference generated between the two electrodes when changing the 11H value of the C measurement solution The results are shown in Table 1. The characteristics of the method described in Example <1> and (2) are shown in Figure 5. In Figure 5, △ indicates Example <'i> , s is Example (2)
C is the characteristic curve of the device of the present invention described in 2. C is the characteristic curve of the pH measuring glass electrode made for high temperatures and the liquid junction part. This is a characteristic curve when measured using a reference electrode with a As shown in the figure, when silver and silver alloys were used as the metal electrode body, it was possible to obtain measurement values equivalent to those obtained by the conventional method. Example (3) A metal electrode body having a structure similar to that shown in Examples (1) and (2) and having an oxide film of silver or a silver alloy formed on its surface was manufactured. . This oxide film is formed by thoroughly cleaning the exposed metal parts, heating them at 100°C for 30 minutes in a constant temperature bath, and then heating them at 100°C for 30 minutes.
-C was formed by heat treatment at 0'C for 11 hours. By using these two types of surfaces (metal electrode bodies on which oxidized films are formed) and assembling a measurement system with the same configuration as above, the difference between the two electrodes when the pl-1 value of the measuring liquid is changed. The generated potential difference was measured.The results are shown in Table 2.As shown in the table, when using an electrode with an oxide film formed on the surface, Alloy or 1
Almost the same potential difference was measured as when using an electrode body made of aluminum, and moreover, a stable potential difference was measured in a short time with respect to 1) 11 changes in the measurement liquid. Comparative Experimental Example (1) Using the same means as in the example shown in -1- below, experiments were also carried out in cases where metal electrode bodies were manufactured by changing the material and shape. In a comparative experiment using platinum as a metal electrode body, the pH value of the measurement solution was changed to pure water → I) H2,2 (acidic) → ptoM1.9 (alkaline) → t)) 12.1 (acidic). ), as shown in Figure 6, the generated potential difference shows a sudden change at the point of change in pl-1, but the value is not stable and forms a steep curve that changes gradually. ) did not show a stable potential difference corresponding to the 1'' value. Because of the twins, the pH value of an aqueous solution can be measured by directly immersing a metal electrode made of a certain type of metal in an aqueous solution.
It also shows that the hydrogen ion concentration in an aqueous solution can be measured. Comparative Experimental Example (2) The indicator electrode and metal electrode described in the example were attached to a pressure vessel that can be heated and pressurized, and their pressure resistance was tested. There was no sign of any abnormality. According to the device of the present invention, both the indicator type (~) and the metal electrode are made of stable ceramic and metal solid materials, and the structure is simple like the above-mentioned Ni'/eT. When applied to hydrogen ion concentration measurement and pH measurement4, it has extremely excellent features and effects as described below: (1) It does not have an internal electrolyte as a reference electrode, and therefore does not require a liquid junction. (2) It does not contaminate the measurement liquid, so it is possible to measure the original hydrogen ion concentration of the measurement liquid. (3) It can be used in liquids at high temperatures. (4) It can be used in liquids under high pressure conditions. (5) The 4Mth-(-Convex 1-) has a column C, making its handling simple and easy. (6) Check out the essential defects in the liquid junction. (7) Changes in characteristics occur during use. When the metal electrode surface is polished or washed, the characteristics can be easily restored and the bendability can be improved. , sensors for measuring the degree of hydrogen ions in aqueous solutions, PT1 measurements for water quality control of various industrial waters, high temperature and high pressure strips.
It can be used for direct measurement of hydrogen ion concentration in an aqueous solution at a small scale, and is industrially useful.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a conventional measuring device, Figure 2 is an explanatory diagram of the configuration of the present invention, and Figure 3 is a test used to investigate the performance of the present invention. A schematic explanatory diagram of the apparatus; Figure 4 is a potential difference measurement diagram when the measuring solution 01-1 was sequentially changed to acidic, alkaline, and acidic using the silver electrode of the present invention; Figure 5 is a diagram showing the implementation of the present invention. FIG. 3 is a graph showing measurement results according to an example, and is a characteristic diagram showing a relationship between an output potential difference corresponding to a change in the pti value of an aqueous solution. FIG. 6 is a potential difference measurement diagram when a platinum electrode (comparative example) is used and the liquid is sequentially changed to pure water, acidic, alkaline, and acidic in the same way as FIG. 5. 1... Indicator electrode 2... Reference electrode 3... Internal electrode 4... Internal electrolyte 5... Liquid junction
6...Potential difference 8110...Indicator electrode
11... Internal electrode 12... Internal electrolyte 13.
...Terminal 14...Shield 15...Measurement liquid 16...Measurement container 20...Metal electrode body 2
1... Insulating coating part 22... Insulating part 23...
Terminal 24... Shield 25... Amplifier 26... Voltage reduction 30... Test WI37.
...Shield 38...Medical solution introduction part 39...Switching (branching) part 40, 41.42...Medical solution tank 43...
・Heating part 44...Temperature level 45...Heating V
iba47...pressure device.

Claims (1)

[Claims] 1. An indicator electrode for hydrogen ion concentration measurement having a terminal connected to one electrode terminal of a measuring device and a metal electrode body having a terminal connected to the other electrode terminal in an aqueous solution. In a device that measures the hydrogen ion concentration in an aqueous solution by directly immersing it in water and measuring the potential difference generated between both terminals with the above measuring device, the indicator electrode for hydrogen ion concentration measurement is connected to a container with a closed end and its interior. has an internal electrode and an internal electrolyte, and the closed end of the metal electrode body is formed of at least a hydrogen ion-sensitive or conductive solid electrolyte, and the surface of the metal electrode body that comes into contact with the aqueous solution is silver, a silver alloy, an oxide of silver or a silver alloy, or a laminate thereof. 2. The hydrogen ion concentration measuring device according to claim 1, wherein the solid electrolyte is stabilized zirconia. 3. The hydrogen ion concentration measuring device according to claim 1, wherein the metal electrode body is a composite metal body in which silver, a silver alloy, or an oxide thereof is coated or laminated on a metal base metal. 4. The hydrogen ion flux measuring device according to claim 1 or 3, wherein the metal electrode body is attached to an insulator, and this insulator serves as a member for attaching the measuring device to the measuring device. 5.1- The hydrogen ion concentration measuring device according to claim 1 or 3, wherein at least a portion of the liquid immersion portion of the metal electrode body is covered with an insulator.