JPH08276184A - Electrode for electrolyzing water - Google Patents

Abstract

PURPOSE: To provide an electrode for electrolyzing water facilitating the dispersion of an ion-containing soln. and gas formed when water is electrolyzed, enhancing ion forming efficiency, efficiently producing acidic ion water and alkaline ion water and simplified in the holding structure of the electrode and a diaphragm. CONSTITUTION: Two electrode plates 5 each having a front surface 1 composed of a conductive material such as a metal and a rear surface 2 composed of a non-conductive material such as plastic and having a large number of through- holes 3 are arranged so that the non-conductive material surfaces 2 thereof are mutually opposed and a diaphragm 4 is arranged between the electrode plates 5 to constitute an electrode for electrolyzing water. This electrode is arranged in an electrolytic cell so as to divide the cell into two parts and one electrode plate is set to an anode and the other electrode plate is set to a cathode to apply voltage across the electrode plates to generate electrolysis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for electrolysis of an aqueous solution containing water and an electrolyte, and more particularly to an electrode for electrolysis of water suitable for producing acidic ion water and alkaline ion water.

[0002]

2. Description of the Related Art It has been conventionally known that acidic ionized water and alkaline ionized water are produced by electrolysis of water. Then, in recent years, various methods and devices have been proposed for producing alkaline ionized water such as health drinking water, or for producing acidic ionized water such as sterilizing water by utilizing this phenomenon. Japanese Patent Fair 4-28
No. 439, Japanese Patent Publication No. 4-57394, JP-A-6
-47376, JP-A-6-55173, JP-A-6-246268). For the conventional electrolysis of water, an electrolyzer is used in which a cathode and an anode are arranged facing each other in the electrolytic cell with a constant gap, and a diaphragm is arranged between the cathode and the anode. It was

[0003]

When electrolyzing water using the conventional electrolyzer having the above-mentioned structure, in order to improve the reaction efficiency of electrolysis, it is necessary to arrange the cathode and the anode as narrow as possible. It is valid. By the way, since electrolysis occurs on both the positive and negative electrode surfaces facing each other across the diaphragm, the solution or gas containing acidic ions and alkaline ions,
It is generated in a narrow gap between the diaphragm and each electrode. In order for the target aqueous solution containing water and the electrolyte to be efficiently electrolyzed, it is necessary to appropriately diffuse the solution containing the generated ions and to diffuse the generated gas. Therefore, it is necessary to appropriately hold both electrodes and the diaphragm in a narrow space while satisfying the above requirements, which causes a problem that the structure of the electrolyzer becomes complicated. The present invention has been made in view of the above circumstances, by facilitating the diffusion of a solution containing ions generated by electrolysis and the diffusion of gas, and by narrowing the distance between both electrodes as much as possible. An object of the present invention is to provide an electrode for water electrolysis in which the electrolysis efficiency is improved and the structure for holding the electrode and the diaphragm in the electrolytic cell is simplified.

[0004]

As a result of various investigations on the structure of the electrode for electrolysis of water in order to achieve the above-mentioned object, the present inventor has found that, unlike the prior art, the electrode between the facing cathode and anode is completely different. The inventors have found that the conventional problems can be solved by causing the cathode and the anode to face each other outward without causing electrolysis, and have completed the present invention.

That is, according to the present invention, the front side is a surface (1) made of a conductive material such as metal, the back side is a surface (2) made of a non-conductive material such as plastic, and a large number of through holes ( Two electrode plates (5) having 3) are arranged so that their non-conductive material surfaces (2) face each other, and a diaphragm (4) is arranged in the middle thereof. It is an electrode for water electrolysis.

The present invention will be described in more detail. When a voltage is applied to negative and positive electrodes placed in an aqueous solution containing water or an electrolyte, electrons move between the electrode and the water or the electrolyte ionized at the electrode surface. On the anode side, when oxygen gas or sodium chloride is used as an electrolyte, chlorine gas is generated and at the same time hydrogen ions, hydronium ions, etc. are generated in the solution, and the solution becomes acidic. At the cathode, hydrogen gas is generated and hydroxide ions are generated, and the solution becomes alkaline. The electrons that have moved from the cathode to the solution move in the solution and reach the anode. That is, electricity flows from the anode to the cathode.

Since the reaction of producing ions and gas is carried out on the electrode surfaces of the anode and the cathode and in the vicinity thereof, the ion concentration becomes higher as it is closer to each electrode surface, and therefore lower as it is farther away, and a difference in concentration occurs. It is generally said that the generated substances such as ions generated in the vicinity of the electrode move or diffuse due to the concentration gradient, the potential gradient, the convection of the solution, etc. as a driving force. The diaphragm arranged between the anode electrode and the anode electrode plays a role of preventing mixing of both solutions generated at the anode and the cathode.

In the case of using an electrode in which a cathode and an anode face each other as in the conventional method and a diaphragm is arranged in the middle, electrolysis actively occurs on the electrode surface of the cathode and the anode on the diaphragm side, and each electrode is Ions and gas are generated at. The gas is diffused as bubbles in the solution existing between the electrode and the diaphragm, and the anions and cations diffuse by the action of concentration gradient, potential gradient, convection and the like. At this time, mixing of both solutions is prevented by the diaphragm, but since there is a potential gradient, ions existing in the solution migrate to the counter electrode side while passing through the diaphragm while performing electrophoresis. This physical phenomenon is applied, for example, when caustic soda is produced by electrolysis of sodium chloride, and sodium ions produced at the anode move to the cathode so that sodium hydroxide can be produced.

However, in the case of producing acidic and alkaline ionized water, which is the object of the present invention, it is necessary to increase the concentration of the produced anions and cations in the produced solution on the electrode side. Therefore, the phenomenon that the ions present in the solution move to the opposite electrode side is not preferable. Therefore, in the present invention, the negative electrode and the positive electrode are not faced to each other, each electrode is directed to the outside, that is, the back face to each other, and the facing side is made of a non-conductive material, and the diaphragm is arranged in the middle. By doing so, the electrolysis reaction is caused on the back electrode surface, ions and gas are generated, the ions existing in the solution are suppressed from moving to the opposite electrode side, and the ion concentration in the solution can be increased. It is the one.

An example of the water electrolysis electrode of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of an electrode for water electrolysis according to the present invention, and FIG. 2 is a sectional view taken along line AA.
(1) is a surface made of a conductive material such as metal, and examples of the material include copper, lead, nickel, chromium, titanium, gold, platinum, iron oxide, graphite, and the like, and platinum is preferable. When using a plate of metal or the like, it is suitable to use a plate of 5 to 100 microns, but use a metal plate of titanium or the like of about 0.1 to 5 mm plated with platinum or the like. May be. (2) is a surface made of non-conductive material such as plastic, and the material is polyethylene resin, polypropylene resin, polystyrene resin, polyethylene terephthalate resin, vinyl chloride resin, ABS resin, acrylic resin, epoxy resin, polyvinyl fluoride resin. Plates of ceramics, natural rubber, SBR, silicon rubber, chloroprene rubber, etc. are used. Further, it may be a synthetic resin plate reinforced with a cloth such as glass fiber, cotton or synthetic fiber, a net, etc., or may be a coating film of a non-conductive paint or a synthetic resin film. The above (1) and (2) are closely laminated so that the solution does not enter in the middle thereof to form an electrode plate (5).

A large number of holes (3) penetrating the electrode plate (5) are punched. The area of each hole (3) is 1 to 500 mm 2, preferably 2 to 3 mm 2.
The hole (3) is located over the entire electrode surface that contributes to electrolysis. The ratio of the total area of the entire holes to the entire surface of the electrode (aperture ratio) is 10 to 90%, preferably 30 to 70%. The size and opening ratio of the holes affect the power efficiency of electrolysis.

Two electrode plates (5) having the above construction are arranged so that their non-conductive surfaces (2) face each other, and a diaphragm (4) is arranged between them. And each electrode plate (5)
And the diaphragm (4) are brought into close contact with each other and integrated, and are connected to each electrode plate (5), and contacts (5 ') for the negative and positive electrodes,
It is attached to a frame (6) for fixing a non-conductive material provided with (5 ′) to form the electrode for water electrolysis of the present invention. The material of the diaphragm (4) is non-woven fabric such as asbestos, glass wool, polyvinyl chloride fiber, polyvinylidene chloride fiber, polyester fiber, aromatic polyamide fiber, etc. that are commonly used, unglazed pottery, paper, ion exchange resin film, etc. is there. In the above example, the electrode plates (5) and the diaphragm (4) are closely adhered to each other, but they may be arranged independently. That is, a spacer made of a non-conductive material is inserted and integrated so that the solution can exist between the non-conductive surface (2) of the electrode plate (5) and the diaphragm (4), and the non-conductive material is formed. It may be attached to the frame (6) for fixing the material.

FIG. 3 is a perspective view of an apparatus for electrolyzing water or an aqueous solution containing an electrolyte using the electrode for water electrolysis of the present invention. (7) is an electrode for water electrolysis,
(8) is an electrolytic cell. The electrode (7) for water electrolysis is installed at approximately the center of the electrolytic layer (8). At this time, the water electrolysis electrode (7) completely separates the aqueous solution in the electrolytic cell (8) so that the aqueous solutions on both sides are not mixed. The electrolytic layer (8) is filled with water or an aqueous solution containing an electrolyte. Next, one electrode plate (5) of the water electrolysis electrode (7) was used as a cathode and the other electrode plate (5) was used as an anode, and the respective contacts (5 '), (5') were energized. Voltage is applied to electrolyze. Further, in the above example, only one electrode for water electrolysis (7) is installed in the electrolytic cell, but two or more electrodes may be installed. When a plurality of such electrodes are installed in this way, they are installed so that the same poles face each other, for example, the anodes face each other.

[0014]

As described above, according to the present invention, the cathode and the anode do not face each other, each faces the outer side, that is, the back side, the facing side is the non-conductive material, and the diaphragm is arranged in the middle. The electrolysis reaction occurs on the back electrode surface to generate ions and gas. At this time, since a current flows between the through hole provided in each electrode plate and the back electrode surface through the diaphragm, the potential gradient exists only in the solution existing between the hole and the diaphragm. , Does not exist in the solution on each back electrode side. Therefore, the anions and cations generated at the respective electrodes move in the direction away from the electrodes due to the concentration gradient and convection, but the potential gradient causes a weak force to move to the opposite electrode. Is difficult to mix. That is, the generated ions are diffused in a direction away from the electrode due to a concentration gradient or convection, and only the ions existing in some of the holes of the electrode plate move to the counter electrode due to the potential gradient. Therefore, the phenomenon of migration of the ions existing in the solution to the counter electrode side is reduced, the concentration of the generated anion and cation is increased in the solution of the generated electrode side, and the acidic and alkaline ionized water is efficiently added. Can be manufactured. Also, the gas is released on the released solution side opposite the diaphragm.

At the time of electrolysis, electricity moves in an aqueous solution containing an electrolyte existing between an anode and a cathode, and the distance between both electrodes and the diaphragm are factors of electric resistance at the time of electrolysis.
In order to increase the power efficiency in electrolysis, it is desirable to narrow the distance between the negative and positive electrodes in order to reduce the electrical resistance, but in the case of a conventional facing electrode with a cathode and an anode facing each other, both electrodes There is a certain limit because it is necessary to consider the movement of the solution and the emission of gas existing during the period. In the case of the back electrode of the present invention in which the cathode and the anode face outward and face to face, it is only necessary to provide an insulating material and a diaphragm between both electrodes, and it is not necessary to consider the movement of the solution and the gas emission. .
Therefore, the distance between the electrodes can be reduced to the total value of the thickness of the electrodes, the insulating material, and the diaphragm used, and thus the power efficiency in electrolysis can be increased.

Example 1. Platinum-plated 1 mm thick titanium plate on one side and non-conductive thickness 0.2 on the opposite side
Of polyethylene film, and the diameter of this laminate is 5
mm holes were evenly punched so that the pitch was 7.7 mm to form an electrode plate. The aperture ratio was 33%. The two electrode plates are arranged so that the polyethylene film surfaces face each other, and a 0.17 mm thick Yumicron membrane filter (Yuasa Battery MF-60B) diaphragm is arranged between them to bring the three into close contact. Then, an electrode was prepared by fixing it on the upper non-conductive mold. Vertical and horizontal of this electrode 100 mm each
The one having a size of 1 was placed substantially in the center of the electrolytic layer having a capacity of 1 liter. With this electrode, the aqueous solution in the electrolytic cell was completely separated and was not mixed. The electrolytic cell was filled with a 0.03 wt% sodium chloride aqueous solution as an aqueous solution containing an electrolyte. Then, using one electrode plate of the above electrodes as an anode and the other electrode plate as a cathode, a direct current was applied at a low voltage of about 13V. Then, changes over time in pH and redox potential (ORP) of the aqueous solution on the anode side and the aqueous solution on the cathode side were measured. Table 1 shows the results. Further, the power efficiency was measured until the pH of the liquid on the anode side reached 2.7, which was 5.1 watt · hour / liter.

[0017]

[Table 1]

Example 2. The diameter of the holes drilled in the electrode plate is 7
mm and the pitch of the arrangement was 10 mm, and electrolysis was performed under the same shape and conditions as in Example 1. The aperture ratio in this case was 44%. Table 2 shows the results of measuring changes in pH and redox potential (ORP) of the aqueous solution on the anode side and the aqueous solution on the cathode side with time. Further, the power efficiency until the pH reached 2.7 was 3.4 watt · hour / liter.

[0019]

[Table 2]

Example 3. An electrode having the same structure as that used in Example 2 and having a size of 360 mm in length and 500 mm in width was used. This electrode was placed in the approximate center of the electrolytic layer having a capacity of 100 liters so that the aqueous solution in the electrolytic cell was completely separated and not mixed. A 0.03% sodium chloride aqueous solution was placed in the electrolytic cell for electrolysis. The current at this time was maintained at about 15V. Changes over time in pH and redox potential (ORP) of the aqueous solution on the anode side and the aqueous solution on the cathode side were measured. Table 3 shows the results. Further, the power efficiency until the pH reached 2.7 was 4.4 watt · hour / liter.

[0021]

[Table 3]

Acidic ionized water at a level below pH 2.7 has good bactericidal activity. According to the usual electrolysis method, the power efficiency for reaching this level varies depending on the conditions, but is usually about 8 to 10 watt · hour / liter. In the case of using the electrode of the present invention, 5.1 in Example 1.
It can be seen that the power efficiency is excellent since it is watt-hour / liter, Example 2 is 3.4 watt-hour / liter, and Example 3 is 4.4 watt-hour / liter.

[0023]

When water or an aqueous solution containing an electrolyte is electrolyzed using the water electrolysis electrode of the present invention, the distance between the negative and positive electrodes of the electrode is reduced to the total value of the thickness of the electrode plate and the diaphragm. Therefore, the power efficiency in electrolysis can be improved. In addition, since there is no generation of ions and gas between the electrode and the diaphragm, it is easy to diffuse the solution and discharge the gas, and the increase in the electrical resistance due to the gas remaining between the electrode and the diaphragm or inside the diaphragm causes The current instability factor is reduced. When the water electrolysis electrode of the present invention is used, the anions and cations generated at each electrode move in the direction away from the electrode due to the concentration gradient and convection, but are attracted to the opposite electrode by the potential gradient. Since the moving force is weak, it is difficult for anions and cations to mix with each other, and the concentration of the target ions can be increased.
It is possible to efficiently produce acidic ionized water and alkaline ionized water. Furthermore, in the conventional method, it is necessary to separately hold the negative and positive electrode plates and the diaphragm,
In the case of the present invention, since it is easy to make a structure in which the electrode and the diaphragm are directly adhered or a spacer is inserted and adhered and integrated, it is possible to simplify the structure for holding in a container or the like to be subjected to electrolysis. The degree of freedom in shape design is widened, and it is easy to manufacture not only flat plates but also curved, spherical, and angular surfaces.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a water electrolysis electrode of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view of an electrolysis device provided with an electrode for water electrolysis according to the present invention.

[Explanation of symbols]

1 surface made of conductive material 2 surface made of non-conductive material 3 hole 4 diaphragm 5 electrode plate 5 '
Contact for negative and positive electrodes 6 Frame for fixing 7 Electrode 8 Electrolyzer

Claims (1)

[Claims] 1. An electrode having a surface (1) made of a conductive material such as metal on the front side and a surface (2) made of a non-conductive material such as plastic on the back side and having a large number of through holes (3). For water electrolysis, characterized in that two plates (5) are arranged so that their non-conductive material surfaces (2) face each other, and a diaphragm (4) is arranged between them. electrode.