JPS61258158A - Electrochemical cell - Google Patents

Abstract

PURPOSE:To obtain a cell which is free from liquid leakage and has low noise, high sensitivity and excellent electrolytic efficiency by using a tube electrode formed by inserting a wire-shaped inside electrode into a tube consisting of an ion exchange membrane and winding an outside electrode on the outside surface of the tube. CONSTITUTION:The wire-shaped inside electrode 13 is inserted into the tube 12 consisting of the ion exchange membrane and the outside electrode 14 is wound on the outside circumference of the tube 12 to form the tube electrode. The tube electrode is freely attachably and detachably attached at both ends to a cap part 18 provided with fluid connecting ports 19, 20 on the outside surface and is dipped into an inside liquid 16 of a case 15. Fluid to be measured or fluid for forming a reagent is introduced into the tube electrode through fluid connecting ports 19, 20 and the polarographic measurement is executed in accordance with the current flowing between the electrodes or the reagent is generated by passing the specified current between the electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Fields> The present invention relates to an analyzer that continuously determines the degree of electrochemical redox substance (m) in a fluid while flowing the fluid to be measured, or a reagent electrolytic generator. The present invention relates to an electrochemical cell suitable for.

<Conventional technology> Conventionally, when continuously measuring the electrochemical redox substance concentration in a fluid to be measured, flow injection analysis (FrA) is used, in which measurement is performed while the fluid to be measured is flowing.
will be held. FIG. 3 is a cross-sectional view of an electrochemical cell of an FIA type analyzer. In the figure, 1 is a main body forming a measurement chamber 2, and pipe lines 3 and 4 are connected to both ends of the measurement chamber 2.

The fluid to be measured is introduced through conduit 3 and discharged through conduit 4 as shown by the arrows. 5 is an indicator electrode, Q is a counter electrode, and these are attached to the inner wall of the measurement chamber 2. 7 is electrode 5.6
There is a polarographic measuring device connected between them.

With this configuration, the fluid to be measured is injected from the conduit 3 at a constant flow rate using a pump or the like, and is guided into the measurement chamber 2, where the electrochemical redox substance contained in the fluid is detected by the polarographic measuring device 17. A current depending on the concentration is detected.

By the way, in such a device, the indicator electrode 5 and the counter electrode 6 attached to the inner wall of the measurement chamber 2 cannot have their surface areas reduced in order to perform high-sensitivity measurements, so they protrude into the measurement chamber 2. The electrode part caused disturbance in the flow of the fluid to be measured. For this reason, there is a drawback that noise (peak tailing) occurs in the measurement signal.

Furthermore, since the indicator electrode 5 and the counter electrode 6 are provided, the volume of the measurement chamber 2 becomes large, and the linear velocity of the fluid to be measured decreases in this part.
A sufficient diffusion rate could not be obtained, and sufficient stability and sensitivity could not be obtained.

On the other hand, there are devices that make reagents using electrolysis.

FIG. 4 is an exploded perspective view of a cell section in such an apparatus. In the figure, 8 is a plate-shaped electrode provided with a through hole 8a.
A fluid passage is formed between the ion exchange membrane 9 and the cover 10. Reference numeral 11 is a container in which a reagent generated by electrolysis is stored, and itself constitutes an electrode. These parts are integrated to form a cell part.

With this configuration, the plate electrode 8 is set to -, the container electrode 11 is set to -, a constant current device is connected between these electrodes, and a fluid for producing a reagent such as K1 is caused to flow as shown by the arrow. In the I'''' ion a vessel 11 that has passed through the ion exchanger 8!9, the reaction 21-→Iz +28- .= (1) occurs to generate 2 as a reagent.

By the way, in such devices, each component has an overlapping structure, which makes it difficult to seal the liquid, and the structure also prevents the gas generated during electrolysis from escaping easily, so this gas reduces the electrolysis efficiency. There were drawbacks.

<Problems to be Solved by the Invention> The technical problems to be solved by the present invention are that when used in an FIA type analyzer, the area of the electrode part is large and high sensitivity measurement can be performed, and the flow of the fluid to be measured is The goal is to realize an electrochemical cell that does not disturb the flow and has low noise. Also, when used in a reagent electrolysis generator, it realizes an electrochemical cell with no liquid leakage and a wide liquid junction area with high electrolysis efficiency. It's about doing.

<Means for Solving the Problems> The present invention has a structure in which a wire-shaped internal electrode is inserted into a tube made of an ion exchange membrane, an external electrode is wound around the outer circumference of the tube, and an internal liquid is connected to the tube electrode. The container is composed of a container in which the tube electrode is immersed, and a lid portion of the container, into which both ends of the tube electrode are detachably attached, and a fluid connection port to the tube electrode is provided on the outer surface. .

Function> The above technical means works as follows. A fluid to be measured or a fluid for reagent generation is introduced into the tube electrode from the fluid connection port, and polarographic measurements are performed based on the current flowing between the electrodes, or by passing a constant current between the electrodes. Now generates reagents.

<Example> The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention.

12 is a tube formed by an ion exchange membrane, 13
14 is a wire-shaped internal electrode (indicator electrode) using, for example, a platinum wire inserted into the tube, and 14 is the tube 12.
An external electrode (counter electrode) made of, for example, a platinum wire is spirally wound around the outer periphery of the tube, and these constitute a tube electrode.

Reference numeral 15 denotes a container containing an internal liquid 16, into which the tube electrode is immersed. Reference numeral 17 indicates a gas handling hole provided in the upper part of the container 15; 18 indicates a container having both ends of the tube electrode attached to the inside thereof and fluid connection ports 19 and 20 to the tube electrode provided on the outer surface thereof; 15
It is a lid part that is coupled to the.

The connection between the tube electrode and the lid 18 is shown in the partially enlarged sectional view of FIG. A ferrule 12a is fixed to the end of the tube electrode, and a push screw 12b is loosely fitted into the inner part of the ferrule 12a. Connect this push screw to the lid part 1.
8, a hole 18a leading to the connection port 19 or 20
The entire tube electrode is removably attached to the lid part 18 by screwing it into the lid part 18.

21 is a polarographic measuring device connected between electrodes 13 and 14. Incidentally, when this device is used as an electrochemical cell of a reagent electrolysis generator, this part becomes a constant current @ position.

The operation of the apparatus according to the embodiment of the present invention configured as described above will be explained. First, a case will be described in which the present invention is used as an analysis device using the FIA method based on polarography. By appropriately selecting the voltage applied between the electrodes 13 and 14 and the internal liquid, and injecting the fluid to be measured into the tube electrode from the connection port 19 at a constant flow rate, the polarographic measurement device 21 detects the electricity in the fluid to be measured. A current corresponding to the concentration of chemical redox substances flows, and the concentration of dissolved oxygen, hydrogen peroxide, residual chlorine, etc. is measured based on this current.

In addition, in such a device, when AQ is used for the internal electrode 13, Ag1 ions are generated, and substances such as CI-, Br-+ I'''', CN-1S'''' that form a precipitate with these ions are subjected to precipitation titration. It can be measured based on the principle of

Next, a case where the device according to the present invention is used in a reagent electrolytic generator will be explained. The iodine standard solution used for direct titration contains strongly reducing substances, such as thiosulfur! l salt,
Sulfite, sulfide, arsenite, ferrocyanide, stannous salt, antimonite, etc. are shown below in the case of thiosulfate (formula (2)) and in the case of sulfite (formula (3)). The reaction formula is shown.

2Na28203+ 12← 2Na I+Naz 5406 ... (2) +2 So)+ I2 +H2o, =2H2SO4+
21-1" +21- ... (3) In this case, if I2 is stored as a reagent, I2 will gradually decrease due to natural decomposition, etc., so it is usually stored in a stable form of KI, Electrolysis is performed as necessary to obtain the desired I2.

When the device according to the present invention is used as such a reagent electrolysis generator, a constant current device 1F21 is connected between the electrodes 13 and 14.
Kr is used for the internal liquid 16, and Kl is also used for the fluid from the connection port 19. When connected to the constant current device 21 with the internal electrode 13 on the + side and the external electrode 14 on one side, the reaction of formula (1) occurs within the tube electrode, and the constant current device 21 ? [2] can be generated in an amount corresponding to the I flow value.

For example, when divalent iron ion Fe2+ is required as a reagent, Fe2+ is unstable like I2, so it is usually stored as a complex ion. If the following electrolysis is performed using this device, FeCN3+e−−+Fe ” ” +3CR−...
(4) FC12+ can be stably supplied as needed.

<Effects of the Invention> According to the present invention, since the electrode portion through which the fluid to be measured passes has a structure in which the wire-shaped internal electrode 13 is inserted into the tube 12, there is no liquid leakage, and there is no leakage inside the tube electrode. No turbulence occurs in the fluid flow. Furthermore, even if the length of the Wl electrode portion is increased ([), the linear flow velocity of the fluid does not decrease, and the liquid junction area of the electrode can be increased. As a result, an electrochemical cell with low noise, high sensitivity, and excellent electrolytic efficiency can be realized.

Furthermore, the main body can be separated into the container 15 and the lid 18, making it easy to replace the internal liquid 16, and since the tube electrode is detachably attached to the lid 18, it is easy to replace the electrode. Maintenance such as polishing can be easily performed.

In the explanation of the embodiments of the present invention up to this point, the electrodes are of a two-electrode type, an indicator electrode and a counter electrode. The present invention can also be applied to a three-electrode type cell in which polarographic measurements are performed based on the current between the indicator electrode 13 and the counter electrode 14 by applying a voltage between the indicator electrode 13 and the reference electrode. No problem, it can be implemented.

[Brief explanation of the drawing]

Fig. 1 is a rM view of the device according to the embodiment of the present invention, Fig. 2 is a partially enlarged sectional view of the device according to the embodiment of the present invention shown in Fig. 1, and Fig. 3 is an FIA
Cross-sectional view showing the conventional structure of an electrochemical cell according to the method, No. 4
The figure is an exploded perspective view showing the conventional structure of a reagent electrolytic generator. 12...Tube, 13...Internal electrode, 14...
External electrode, 15... Container, 16... Internal liquid, 18.
...Lid, 19.20...Fluid connection port, 21...Bolarogranoic measuring device or constant current device Fig. 1 Fig. 2

Claims (1)

[Claims] A tube electrode with a wire-shaped internal electrode inserted into a tube made of an ion exchange membrane and an external electrode wound around the outer circumference of the tube, a container with the tube electrode immersed in an internal solution, and a container with the tube electrode inside. The lid of the container is detachably attached at both ends and has a fluid connection port to the tube electrode on its outer surface, and a fluid to be measured or a reagent is introduced into the tube electrode from the fluid connection port. An electrochemical cell in which a generation fluid is introduced and polarographic measurements are performed based on the current flowing between the electrodes, or a reagent is generated by passing a constant current between the electrodes.