JP4390979B2 - Coulometric titrator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coulometric titration apparatus used, for example, for titration of a liquid hydrogen ion concentration (pH), and more particularly to a coulometric titration apparatus that allows a cathode to be installed easily and in a short time.
[0002]
[Prior art]
Coulometric titration is a titration method in which a titration reagent is generated by electrolysis, and the amount of electricity applied until the end of titration is measured until the end of titration, and a sample is quantified from the law of electrolysis.
[0003]
As an apparatus for realizing the above method, there are a configuration in which a diaphragm is provided between a cathode and an anode, and a configuration in which the diaphragm is not provided. The structure including the diaphragm includes, for example, an electrolytic cell for storing a sample solution and an electrolytic cell inserted from above into the electrolytic cell, as described in Japanese Utility Model Publication No. 62-10686. Is formed with a cathode chamber whose lower end surface is closed by a porous electrolytic diaphragm. In the electrolytic cell, the space outside the electrolysis cell is called an anode chamber, and a cathode is disposed in the cathode chamber and an anode is disposed in the anode chamber with the electrolytic cornea interposed therebetween.
[0004]
A configuration without a diaphragm is, for example, the configuration shown in FIG. 4, and includes an electrolytic cell 2 that stores the sample solution 1 and an electrolytic cell 3 that is inserted into the electrolytic cell 2 from above. An anode 4 in contact with the sample solution 1 outside the cell 3 and a cathode 5 in contact with the sample solution 1 in the cell 3 are provided, and no electrolytic diaphragm is provided between the electrodes 4 and 5.
[0005]
In such a coulometric titration apparatus without an electrolytic diaphragm, since it is necessary to increase the current density of the cathode 5, the conductive wire 7 connecting the cathode 5 to a measurement circuit (not shown) is embedded in the tube 6 of the electrolytic cell 3, for example. It is made not to contact with the liquid 1.
In the electrolytic cell 2, each chamber divided into two chambers inside and outside the electrolytic cell 3 is called the anode chamber 8 on the outside of the electrolytic cell 3 and the cathode chamber 9 on the inside.
[0006]
Here, the tubular body 6 of the electrolytic cell 3 is made of glass, and for example, a platinum wire is used as the conductive wire 7, so that the tip of the conductive wire 7 on the cathode 5 side is placed in the tubular body 6 of the electrolytic cell 3. As an embedding method, for example, the following method is adopted.
As shown in FIG. 5, the conducting wire 7 is inserted into an insulating tube 10 made of a glass thin tube, and the tip of the conducting wire 7 is previously drawn out from the tip of the insulating tube 10 by the length of the cathode 5, and this insulating tube 10 is electrolyzed. It is inserted from above the cell 3 and welded to the peripheral surface of the cathode chamber 9. Thereafter, the tip end portion of the conducting wire 7 is bent toward the peripheral surface of the cathode chamber 9 opposite to the insulating tube 10 and the tip end is fixed.
[0007]
The tip of the cathode side conductor 7 is abutted against the inner surface of the tube body 6, a glass rod for raising is applied to the periphery thereof, and a high temperature gas flame is blown from the hollow portion side of the tube body 6 to It fixes to the inner surface of the pipe body 6 by the method of melt | dissolving and cooling the inner surface of the pipe body 6. FIG.
As an alternative to this method, for example, as shown in FIG. 6, both ends of the cathode 5 are fixed in advance to the inner surface of the tube body 6 in the cathode chamber 9, and then the insulating tube 10 through which the conducting wire 7 is inserted is used in the electrolytic cell 3. Is inserted into the cathode chamber 9 from above and welded to the inner surface of the cathode chamber 9. Thereafter, a method of welding the tip of the conducting wire 7 to the electrode 5 is employed.
[0008]
[Problems to be solved by the invention]
When the above-described method shown in FIG. 5 is adopted, the insulating tube 10 through which the conducting wire 7 is inserted is inserted into the cathode chamber 9 from above the electrolysis cell 3 and welded to the peripheral surface of the cathode chamber 9. There is a problem that it is necessary to perform welding on the peripheral surface of the chamber 9, which is very troublesome and requires highly skilled work.
[0009]
Further, in the method shown in FIG. 6, it is necessary to weld both ends of the cathode 5 to the inner surface of the cathode chamber 9, which is further troublesome and the cathode 5 and the conductor 7 must be welded in the narrow cathode chamber 9. Therefore, troublesome and difficult work is further increased.
[0010]
An object of the present invention is to solve such a technical problem of the prior art and to provide a coulometric titration apparatus in which a cathode can be installed easily and in a short time.
[0011]
[Means for Solving the Problems]
The present invention comprises an electrolytic cell for storing a sample solution, and an electrolytic cell that is inserted into the electrolytic cell from above and supports a cathode inside and an anode at the lower end, and is disposed in a cathode chamber formed in the electrolytic cell. In the coulometric titration apparatus in which the conductive wire connected to the cathode is insulated from the sample solution, the following means are adopted in order to achieve the object.
[0012]
That is, the cathode is formed by pulling the leading end of the conducting wire inserted through the insulating tube out of the leading end of the insulating tube and winding it around the leading end of the insulating tube. The insulating tube is placed inside the electrolytic cell. A means of inserting into the formed cathode chamber and fixing at a predetermined position in the cathode chamber is adopted.
[0013]
As a result, the cathode can be easily and quickly formed in the insulating tube by passing the cathode lead wire through the insulating tube in advance and pulling the tip out of the insulating tube and winding it around the insulating tube. Can be supported. Then, the insulating tube supporting the cathode is inserted into the electrolysis cell, and fixed to a predetermined position in the electrolysis cell by welding, fusion, adhesion, adhesion, etc. Can be fixed at a predetermined position. As a result, troublesome and highly skilled work such as fixing the cathode to the peripheral surface of the cathode chamber in the narrow cathode chamber required in the prior art or welding the lead wire and the cathode is unnecessary. become.
[0014]
By the way, in this invention, materials, such as an electrolyzer, a tubular body of an electrolytic cell, and an insulating tube, are not particularly limited as long as they have insulating properties, but glass is usually used. Therefore, it is extremely easy to weld the tubular body of the electrolytic cell and the insulating tube together by applying the insulating tube to the inner peripheral surface of the electrolytic cell and heating from the outside of the electrolytic cell.
[0015]
In addition, the number of turns of the tip of the cathode conducting wire wound around the lower end of the insulating tube is not particularly limited, but the current density is set so that the diameter of the insulating tube is such that the tip of the cathode conducting wire is wound once. It is preferable to design the diameter so as to keep it.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
A coulometric titration apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a cross-sectional view showing the configuration of the present invention, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG.
[0017]
As shown in FIG. 1, the coulometric titration apparatus includes an electrolytic cell 2 for storing a sample solution 1 and an electrolytic cell 3 that is detachably inserted into the electrolytic cell 2 from above. The electrolytic cell 3 is made of glass. A tubular body 6, a cathode 5 disposed in a cathode chamber 9 formed in the tubular body 6, and an anode 4 fixed to the lower end of the tubular body 6.
[0018]
The cathode chamber 9 is formed in a vertical cylindrical shape having a circular cross section and an open lower surface 6a. Further, as shown in FIGS. 1 to 3, the cathode chamber 9 has four sides at a predetermined height from its lower end. An opening 6b is formed toward the front.
[0019]
The electrolysis cell 3 has an insulating tube 10 fixed so that a lower end portion is located at a predetermined height from the anode 4 at the center of the cathode chamber 9, and is inserted into the insulating tube 10 in advance, And a cathode-side conductive wire 7 drawn out from the lower end of the insulating tube 10 and wound around the outer periphery of the insulating tube 10.
[0020]
The insulating tube 10 is bent into a shape in which an L shape is abutted from above and below, and a portion below the bent portion is formed of a glass tube having a predetermined outer diameter, and its upper end is fused to the ceiling 11 of the cathode chamber 9. In addition, a portion below the bent portion is connected to the peripheral surface of the cathode chamber 9 by a glass support member 12.
[0021]
The upper end portion of the insulating tube 10 is inserted into a lower hole 13 formed in the ceiling 11, for example, and is fused to the ceiling 11 by blowing a gas flame from the outside of the tube body 6. At this time, the gap between the upper end portion of the insulating tube 10 and the conductive wire 7 inserted therethrough is sealed with molten glass.
[0022]
Further, one end of the connecting shaft 12 is fused in advance to the insulating tube 10 outside the electrolytic cell 3, and the other end of the connecting shaft 12 is assembled together with the insulating tube 10 from the outside of the tube 6. Is sprayed and fused to the peripheral surface of the cathode chamber 9.
[0023]
The lower end portion of the cathode wire 7 on the cathode line passes through the peripheral wall of the lower end portion of the insulating tube 10, is drawn outside the insulating tube 10, and is wound around the insulating tube 10 once. The cathode 5 in contact with the sample solution 1 is constituted.
[0024]
The anode 4 is made of a platinum wire mesh, inserted into another insulating tube 14 disposed in the cathode chamber 9, and connected to the anode-side conductor 15 drawn out from the lower end of the tube 6 to the outside of the tube 6. is doing.
[0025]
The electrolytic cell 2 is provided with an inlet for injecting the sample solution 1 into the anode chamber 8, an end point detection electrode 16 for detecting the end of electrolysis, and an air communication port 17 for communicating the anode chamber 8 with the atmosphere. In addition, if necessary, a dryer filled with a desiccant is attached to the atmosphere communication port 17 to prevent moisture in the atmosphere from entering the anode chamber 8. In the anode chamber 8, a stirrer 19 for stirring the sample solution 1 is provided.
[0026]
Further, if necessary, the electrolysis cell 2 is formed with a communication hole (not shown) for communicating the upper part of the anode chamber 8 and the upper part of the cathode chamber 9. 9 is prevented from causing an abnormal increase in the internal pressure of one of the chambers or an oxidizing atmosphere in the anode chamber 8.
[0027]
Now, as described above, in this coulometric titration apparatus, outside the electrode cell 3, the cathode side conductor 7 is inserted into the insulating tube 10, and the tip of the conductor 7 is drawn out from the tip of the insulating tube 10 to the outer peripheral surface thereof. The cathode 5 is formed by winding, and then the insulating tube 10 is inserted into the cathode chamber 9 and disposed at a predetermined position. Thereafter, the insulating tube 10 is heated from the outside of the electrolysis cell 3. Is fixed at a predetermined position in the cathode chamber 9.
[0028]
Therefore, it is possible to fix the cathode 5 at an accurate position much more easily, in a short time, compared with the case where the gas flame is blown into the narrow cathode chamber 9 to fix the cathode 5 in the tube body 6. It can be done.
[0029]
In this embodiment, the end of the cathode 5 is welded to the winding start portion of the cathode 5 wound around the insulating tube 10, but this welding operation can also be performed outside the cathode chamber 3, Compared to the case where the cathode 5 and the cathode-side conductor 7 are welded in the narrow cathode chamber 9, the welding can be performed much more easily and in a short time.
[0030]
In the present invention, the wire diameter and the development length of the cathode 5 are not particularly limited, but it is preferable to design them so as to maintain an appropriate current density. Further, the outer diameter of the insulating tube 10 and the winding number of the conducting wire 7 are not particularly limited, but it is preferable to design the insulating tube 10 so as to maintain an appropriate current density with one winding.
[0031]
【The invention's effect】
As described above, the present invention provides an insulation that is fixed to a cathode chamber formed in a body of the electrolysis cell so that a lower end portion is positioned at a predetermined height from the anode at the center of the electrolysis cell. A tube and a cathode-side lead wire, which is inserted in advance into the insulating tube and whose leading end is drawn from the lower end of the insulating tube and wound around the outer periphery of the insulating tube, and is wound around the insulating tube. Since the cathode is constituted by the tip of the attached conducting wire, the tip of the cathode conducting wire is wound around the insulating tube outside the cathode tube, and the cathode is supported by the insulating tube. By disposing at the predetermined position, it is possible to obtain an effect that the cathode can be accurately disposed at a predetermined position in the cathode chamber easily and in a short time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the configuration of the present invention.
FIG. 2 is a cross-sectional view of a main part of the present invention.
FIG. 3 is a configuration diagram of a conventional example.
FIG. 4 is a cross-sectional view of a main part of a conventional example.
FIG. 5 is a cross-sectional view of a main part of a conventional example.
FIG. 6 is a cross-sectional view of a main part of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sample liquid 2 Electrolysis tank 3 Electrolysis cell 4 Anode 5 Cathode 6 Tube 7 Conductor 9 Cathode chamber 10 Insulation tube

Claims (1)

An electrolytic cell for storing the sample solution and an electrolytic cell inserted into the electrolytic cell from above and supporting the cathode and the anode are connected to a cathode disposed in a cathode chamber formed in the electrolytic cell. In a coulometric titrator where the conductor is insulated from the sample solution,
A cathode is formed by pulling the leading end portion of the conducting wire inserted through an insulating tube that insulates the conducting wire from the sample solution, and winding it around the leading end portion of the insulating tube. A coulometric titration apparatus, which is inserted into a cathode chamber formed in a tube of an electrolysis cell and fixed at a predetermined position in the cathode chamber.

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