JP2007277632A - Method for producing ozone water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing ozone water, which can easily produce a high concentration of ozone water even by using distilled water having low electroconductivity as raw water. <P>SOLUTION: A catalyst electrode 2 comprises: a plurality of cation exchange membranes 211 and 212 stacked so as to face each other; a catalyst 3 provided on each facing surface of the plurality of the cation exchange membranes 211 and 212; an anode electrode 22 pressure-welded onto the surface in a side opposite to the catalyst 3 of the cation exchange membrane 211; and a cathode electrode 23 pressure-welded onto the surface in a side opposite to the catalyst 3 of the cation exchange membrane 212. The production method includes applying direct current voltage between the anode electrode 22 and the cathode electrode 23, and bringing the raw water in contact with the anode electrode 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for generating ozone water that generates ozone water by electrolysis of water.

In recent years, ozone water has been widely used for applications such as sterilization of foods and deodorization of malodorous gases, and many examples of knowledge have begun to be published in the fields of medical care and nursing care. Also in the semiconductor manufacturing area, the feature of ozone oxidation with respect to the ultrafine structure is recognized, and the use of ozone water is essential.
As such a method for producing ozone water, the anode electrode is pressed against one surface of the cation exchange membrane, and the raw material water is brought into direct contact with the electrolytic surface of the catalyst electrode formed by pressing the cathode electrode against the other surface. The thing using the direct electrolysis method which produces | generates ozone water by electrolysis of is known (for example, refer patent document 1).

For applications such as food sterilization and deodorization of malodorous gases, it is sufficient to use cheap tap water as raw water, but in the medical and semiconductor fields, distilled water, pyrogen-free water, and more Ultrapure water is required.
JP-A-8-134678

However, the biggest problem when generating ozone gas or ozone water using electrolysis is the conductivity of raw material water. When many minerals are dissolved in water like tap water, Electrolysis is easy because of its high conductivity, but distilled water, pyrogen-free water from which exothermic substances have been removed, and ultrapure water used in semiconductor processing have extremely low electrical conductivity. In order to generate ozone water by the electrolytic method, several methods for accelerating the movement of hydrogen in the cation exchange membrane are required.
One method is to use lead dioxide with high catalytic activity for the anode electrode, but in order to avoid the toxicity of lead, it is necessary to take ozone gas once out of the system and dissolve it in water. Currently, it is used in semiconductor manufacturing equipment. As another method, there is a cathode water method in which the cathode electrode is brought into contact with highly conductive cathode water such as salt water or citric acid water, which is used in quite a few fields. It is considered a drawback to take.
In addition, recently, the inventors have succeeded in electrolysis of distilled water and the like by using silver chloride for the cathode electrode, and also succeeding in electrolysis of distilled water, but the silver chloride is reduced by hydrogen generated from the cathode electrode. It was necessary to take measures to prevent this.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of generating ozone water that can easily generate high-concentration ozone water even when distilled water with low conductivity is used as raw water. Yes.

Therefore, the present inventors changed the conventional cation exchange membrane between the anode electrode and the cathode electrode to only one piece, and used a plurality of thin films in a stacked manner. It was invented to accelerate the movement of hydrogen with the catalyst in between.
In order to solve the above-mentioned problem, the invention of claim 1 is characterized in that, for example, as shown in FIG. 1, a plurality of cation exchange membranes 211, 212 are stacked to face each other, The catalyst 3 is provided on the opposite surface,
The anode electrode 22 is pressed against the surface of one of the plurality of cation exchange membranes opposite to the catalyst, and the other cation exchange membrane on the surface opposite to the catalyst. The cathode electrode 23 is pressed to form the catalyst electrode 2,
A direct current voltage is applied between the anode electrode and the cathode electrode, and raw water is brought into contact with the anode electrode to generate ozone water.

According to the first aspect of the present invention, since the catalyst is provided on the mutually facing surfaces of the plurality of cation exchange membranes, a direct current voltage is applied between the anode electrode and the cathode electrode, and the raw water is brought into contact with the anode electrode. Thus, hydrogen in the raw material water passes through the cation exchange membrane and moves to the cathode electrode. At this time, the movement is promoted by the action of the catalyst between the plurality of cation exchange membranes. As a result, even when distilled water or the like having low conductivity is used as raw water to extract hydrogen, ozone can be generated at the anode electrode, and high-concentration ozone water can be generated.
Moreover, ozone water can be easily generated with a simple structure only by providing the catalyst on the surfaces of the plurality of cation exchange membranes facing each other.

The invention of claim 2 is a method for producing ozone water according to claim 1, for example, as shown in FIG.
The catalyst 3A is silver chloride.

  According to the invention of claim 2, since the catalyst is silver chloride, it has a high ion mobility necessary for ozone generation and has high thermal conductivity, so that the movement of hydrogen from the anode electrode to the cathode electrode is further accelerated. Even if distilled water with low conductivity is used as raw material water, a sufficient electrolysis current flows, ozone is generated, and ozone water can be generated. In addition, the cost is lower than that of an alloy made of silver and palladium. Furthermore, even if silver chloride is used as the catalyst, reduction by hydrogen generated from the cathode electrode can be suppressed.

The invention of claim 3 is, for example, in the method for generating ozone water according to claim 1, as shown in FIG.
The catalyst 3 is a chlorinated compound.

  According to the invention of claim 3, since the catalyst is a chlorinated compound, the movement of hydrogen from the anode electrode to the cathode electrode can be further accelerated, and sufficient electrolysis is possible even when distilled water having low conductivity is used as the raw water. Electric current flows, ozone is generated, and ozone water can be generated. In addition, the cost is lower than that of an alloy made of silver and palladium.

The invention of claim 4 is a method for producing ozone water according to claim 1, for example, as shown in FIG.
The catalyst 3B (or 3C) is an alloy composed of silver and palladium.

  According to the invention of claim 4, since the catalyst is an alloy composed of silver and palladium, the movement of hydrogen from the anode electrode to the cathode electrode can be further accelerated. High concentration ozone water can also be produced as raw water.

The invention of claim 5 is, for example, as shown in FIG. 3, in the method for generating ozone water according to claim 4,
The catalyst 3B (or 3C) has a thin film shape, and the thin film catalyst is fixed to the mutually facing surfaces of the plurality of cation exchange membranes.

  According to the invention of claim 5, since the thin-film catalyst is fixed to the mutually opposing surfaces of the cation exchange membrane, for example, ozone water is generated inferior to the case where the alloy is made of an expensive wire mesh. In addition, the cost can be reduced.

The invention of claim 6 is a method for producing ozone water according to claim 5, for example, as shown in FIG.
The thin film catalyst is fixed to the surfaces of the plurality of cation exchange membranes facing each other by sputtering.

  According to the invention of claim 6, since the thin-film catalyst is fixed to the mutually opposing surfaces of the cation exchange membrane by sputtering, the adhesion of the catalyst to the cation exchange membrane can be increased, and the catalyst can be easily formed. Can be membrane.

  According to the present invention, since the catalyst is provided on the surfaces of the plurality of cation exchange membranes facing each other, high-concentration ozone water can be generated even when distilled water or the like having low conductivity is used as raw material water, and easily with a simple structure. Can be generated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view schematically showing an outline of the ozone water generator 100.
First, the ozone water generating apparatus 100 used in the ozone water generating method according to the present invention will be described. The ozone water generating device 100 is configured by arranging a catalyst electrode 2 in a water tank 1 into which raw water (for example, water) flows, and generates ozone bubbles by applying a DC voltage to the catalyst electrode 2. The device generates ozone water by dissolving the ozone bubbles in water.
The water tank 1 is formed in a cylindrical shape that is vertically long and closed at both upper and lower ends, and an inflow pipe 11 for inflowing raw material water into the water tank 1 is provided on the bottom surface of the lower end. An outflow pipe 12 for outflowing ozone water generated in the water tank 1 is provided on the peripheral surface of the section.
The inflow pipe 11 is connected to, for example, a small pump with a low discharge pressure connected to a tank in which raw water is stored, or a water tap. The outflow pipe 12 is connected to a pump for connecting to a tank for storing ozone water generated in the water tank 1, a nozzle for ejecting ozone water generated in the water tank 1, and the like.
The raw water is introduced into the water tank 1 through the inflow pipe 11, and a water flow is generated from the inflow pipe 11 to the outflow pipe 12.
Moreover, the opening part 13 which the part opened is formed in the side peripheral surface which forms the water tank 1, The catalyst electrode 2 is engage | inserted and attached to the opening part 13. As shown in FIG.

The catalyst electrode 2 includes two cation exchange membranes 211 and 212 arranged opposite to each other, a catalyst 3 pressed against the cation exchange membranes 211 and 212, and both surfaces of one cation exchange membrane 211. Anode electrode 22 in pressure contact with the outer surface (surface opposite to catalyst 3) and cathode electrode in pressure contact with the outer surface (surface opposite to catalyst 3) of both surfaces of the other cation exchange membrane 212 23. The anode electrode 22 is disposed in the water tank 1, and the cathode electrode 23 is attached so as to protrude outward from the outer peripheral surface of the water tank 1 and to be exposed to the outside. Further, a cation exchange membrane 212 with which the cathode electrode 23 is pressure-contacted is disposed so as to be fitted in the opening 13 and substantially flush with the inner and outer peripheral surfaces of the water tank 1. In addition, between the opening part 13 and the catalyst electrode 2, it is set as the structure where the waterproofing process is made and the raw material water in the water tank 1 does not leak. By disposing the catalyst electrode 2 in this way, the raw material water that has flowed into the water tank 1 from the inflow pipe 11 is in continuous contact with the surface of the anode electrode 22.
An output terminal 24 of a power supply device (not shown) is electrically connected between the anode electrode 22 and the cathode electrode 23 so that a DC voltage is applied. That is, the anode electrode 22 and the cathode electrode 23 are connected to the power supply device via the conductive wires to the electrodes 22 and 23. The applied DC voltage is preferably 6 to 15 volts, for example.

  As the two cation exchange membranes 211 and 212, conventionally known ones can be used, and a fluorine-based cation exchange membrane having a high durability against the generated ozone can be used. 300 μm is preferred.

As the catalyst 3, lead dioxide, chlorine compounds such as silver chloride and tin chloride, alloys of silver and palladium, and the like can be used. It is preferable that the lead dioxide or tin chloride is powdered and dispersed on one cation exchange membrane 211 (or 212) and pressed by the other cation exchange membrane 212 (or 211). FIG. 1 shows a case where a powdered catalyst 3 is used.
Moreover, when using silver chloride as the catalyst 3, as shown in FIG. 2, it is preferable to use the thin silver wire net | network 3A which gave silver chloride coating | cover. In this case, it is effective in that silver chloride can be easily coated. In FIG. 2, 211A and 212A are cation exchange membranes similar to the cation exchange membranes 211 and 212 described above.
Further, when an alloy of silver and palladium is used, it is preferably a thin film, and is formed on one cation exchange membrane 211 (or 212) by a vapor deposition method such as sputtering. The thickness is preferably about 0.5 μm. In the case of a thin film, the thin film catalyst 3B has a large number of circular holes 31B, 31B,... As shown in FIG. 3 (a), and the thin film as shown in FIG. It is preferable to form a large number of rectangular holes 31C, 31C,. By forming a large number of holes 31B, 31B, ..., 31C, 31C, ... in the thin film catalysts 3B, 3C, hydrogen ions can pass through the large number of holes 31B, 31B, ..., 31C, 31C, ... It is possible to prevent the hydrogen ions from flowing through the catalysts 3B and 3C. In addition, the shape, the number, the arrangement, and the like of the holes 31B and 31C can be changed as appropriate.

  The anode electrode 22 is not in close contact with the cation exchange membrane 211 so as to cover the entire surface. The anode electrode 22 is provided with a large number of through holes, and the anode electrode 22 is connected to the cation exchange membrane 211 with a contact portion and a non-contact portion. Are stacked. That is, it is preferable that the anode electrode 22 has a grating shape or a punching metal shape. FIG. 1 shows a case where the anode electrode 22 has a grating shape. Specifically, the grating shape is a lattice shape in which wires are welded, and the punching metal shape is a porous plate shape in which a large number of through holes are formed in a metal plate.

  As the anode electrode 22, a metal having an ozone generation catalytic function is used, and lead dioxide is most widely known as this metal. However, this lead dioxide is difficult to process and uses a porous body with irregularly small pores, but the porous body of lead dioxide is fragile and inferior in durability, and lead elutes into ozone water. Therefore, in order to obtain pure ozone water, it is preferable to use a platinum or platinum-coated metal electrode, and in the present invention, it is particularly preferable to use a metal in which titanium is coated with platinum. The coating process can be performed by, for example, plating or heat deposition.

  By using the grating-like anode electrode 22 in this way, the intersection part P of the members constituting the anode electrode 22 is pointed and protrudes to the outer surface to generate a vortex in contact with the water flow. Bubbles can be involved to accelerate dissolution.

As the cathode electrode 23, it is preferable to use a metal such as gold, silver, platinum, titanium, or a thin silver wire mesh whose surface is coated with silver chloride. The cathode electrode 23 is also preferably formed in a grating shape like the anode electrode 22. In particular, the cathode electrode 23 is preferably formed so as to have coarser eyes than the anode electrode 22.
The two cation exchange membranes 211 and 212, the catalyst 3, the anode electrode 22 and the cathode electrode 23 are formed in a flat plate shape along the inner or outer peripheral surface of the water tank 1, respectively. After being brought into close contact, the catalyst electrode 2 is formed by bonding with an insulating bonding member (not shown).

Next, an ozone water generation method using the ozone water generation apparatus 100 having the above-described configuration will be described.
Raw material water is caused to flow into the water tank 1 from the inflow pipe 11, and the raw material water is continuously brought into contact with the surface of the anode electrode 22. At the same time, a predetermined voltage is applied between the anode electrode 22 and the cathode electrode 23 by driving the power supply device. By this energization, the raw water is electrolyzed, and by the action of the catalyst 3, hydrogen in the raw water passes through the cation exchange membranes 211 and 212 from the anode 22 side and accelerates and moves to the cathode 23 side. . As a result, ozone bubbles are generated on the anode electrode 22 side, and hydrogen bubbles are generated on the cathode electrode 23 side.

Here, on the anode electrode 22 side, the direction of the flow of raw material water is complicated due to slight unevenness of the anode electrode 22 and becomes a vortex. Therefore, on the anode electrode 22 side, the generated ozone bubbles are quickly taken into water and dissolved to generate ozone water, and between the anode electrode 22 and the cation exchange membrane 21 (more precisely, the anode electrode 22 and the cathode electrode). 23), a state where a large amount of current flows is ensured.
When ozone water is generated in this way, the ozone water flows out to the outflow pipe 12 and is stored in an ozone water storage tank or the like.
On the other hand, hydrogen bubbles are generated on the cathode electrode 23 side, and hydrogen bubbles are released from the surface of the cathode electrode 23 exposed on the outer peripheral surface of the water tank 1 to the outside of the system.

As described above, according to the embodiment of the present invention, since the catalyst 3 is provided on the surfaces of the cation exchange membranes 211 and 212 facing each other, a DC voltage is applied between the anode electrode 22 and the cathode electrode 23. By bringing the raw material water into contact with the anode electrode 22, hydrogen in the raw material water passes through the cation exchange membranes 211 and 212 and moves to the cathode electrode 23. At this time, the movement of the catalyst 3 is promoted by the action of the catalyst 3. Will be. As a result, even when distilled water or the like having low conductivity is used as raw material water to extract hydrogen, ozone can be generated at the anode electrode 22 and high-concentration ozone water can be generated.
In addition, ozone water can be easily generated with a simple structure simply by providing the catalyst 3 on the surfaces of the cation exchange membranes 211 and 212 facing each other.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can change suitably.
For example, although two cation exchange membranes 211 and 212 are used, three or more may be used. In this case, although not shown, a structure in which the catalyst is sandwiched between the cation exchange membranes is desirable, and a lattice-like catalyst is particularly preferable.

Further, a concentration detection sensor (not shown) for detecting the ozone concentration of ozone water may be provided in the water tank 1 so that the power supply device controls the energization to the catalyst electrode 3 based on the detected ozone concentration. good. Specifically, the concentration detection sensor includes a detection electrode and a reference electrode serving as a reference for potential measurement, a potentiometer connected to one end of the detection electrode and the comparison electrode to measure a potential, and the like. The tip of the comparison electrode (the other end) is immersed in the solution in the water tank 1, and the concentration is measured by detecting the potential difference between the detection electrode and the comparison electrode due to the ozone concentration change of the detection electrode.
As the detection electrode, for example, an electrode made of platinum or gold is preferably used, and silver / silver chloride is preferably used as the comparison electrode. The power supply device controls the voltage between the anode electrode 22 and the cathode electrode 23 so that the ozone concentration detected in this manner matches the preset ozone concentration.

Although not shown, an impeller driven by a pump may be provided in the water tank 1. In this case, since a swirling water flow is generated in the water tank 1, the solubility of ozone generated from the anode electrode 22 can be increased by reliably bringing the raw material water into contact with the surface of the anode electrode 22.
Further, the shape of the water tank 1 and the positions of the inflow pipe 11 and the outflow pipe 12 can be changed as appropriate.

[Example]
Next, the effect of the method for generating ozone water according to the present invention will be described with reference to examples.
(Invention Example 1)
Two cation exchange membranes using a 1.2 mm thick titanium grating with platinum plating on the anode electrode and a 0.2 mm thick silver grating with a silver chloride coating on the cathode electrode For this, a naphthion 1110 membrane made by DuPont was used. Further, as the catalyst, the same silver chloride as that of the cathode electrode was used, and a 40-mesh silver wire mesh coated with silver chloride was used. Then, a catalyst electrode in which these catalyst, two cation exchange membranes, an anode electrode and a cathode electrode are overlapped and pressed is disposed at a predetermined position in the water tank as shown in FIG. 1, and distilled water is supplied from the inflow pipe. Then, when a DC voltage of 12 V was applied between the anode electrode and the cathode electrode, a current of about 8 A flowed at a flow rate of 2 L / min, and 3 ppm of ozone water was obtained from the outflow pipe. Further, when the silver metal mesh coated with silver chloride as a catalyst was examined, it was confirmed that the state was exactly the same as before use, and reduction by hydrogen generated at the cathode electrode was not performed. Therefore, the effect of the present invention is recognized.
(Invention Example 2)
In Example 1 of the present invention, a catalyst alloy of 90 wt% palladium and 10 wt% silver was deposited on the inner surface of one cation exchange membrane by a sputtering method in a vacuum atmosphere to form a thin film having a thickness of 1.5 μm. In addition, the anode electrode, the cathode electrode, and the two cation exchange membranes were the same as those of Example 1 of the present invention, and were supplied with pyrogen-free water from the inlet pipe under the same conditions as described above, and energized. The current flowed 12A, and 5 ppm of ozone water was obtained from the outflow pipe. Therefore, the effect of the present invention is recognized.
(Comparative example)
In Example 1 of the present invention, when a catalyst electrode without a catalyst provided between two cation exchange membranes was used, pyrogen-free water was supplied from the inflow pipe under the same conditions as described above, and energization was performed. Only flowed 2A, and the water flowing out of the outflow pipe did not contain ozone. Therefore, it was found that ozone was not generated.
As is clear from the above results, the present invention produces high concentration ozone water of 4 ppm or more necessary for medical, especially surgery, even when distilled water or pyrogen flow water having a high electrical resistance value is used as raw material water. can do.

1 is a longitudinal sectional view schematically showing an outline of an ozone water generator 100. FIG. It is a perspective view of catalyst 3A which shows a modification. FIG. 6 shows a modification, in which (a) is a plan view of the catalyst 3B, and (b) is a plan view of the catalyst 3C.

Explanation of symbols

2 Catalyst electrodes 3, 3A, 3B, 3C Catalyst 22 Anode electrode 23 Cathode electrodes 211, 212 Cation exchange membrane

Claims (6)

A plurality of cation exchange membranes are stacked facing each other, and a catalyst is provided on the mutually facing surfaces of the plurality of cation exchange membranes,
An anode electrode is pressed against a surface of one of the plurality of cation exchange membranes on the side opposite to the catalyst, and a cathode on the surface of the other cation exchange membrane on the side opposite to the catalyst. The electrode is pressed into a catalyst electrode,
A method for generating ozone water, comprising generating ozone water by applying a DC voltage between the anode electrode and the cathode electrode and bringing the raw material water into contact with the anode electrode.   The method for producing ozone water according to claim 1, wherein the catalyst is silver chloride.   The method for producing ozone water according to claim 1, wherein the catalyst is a chlorinated compound.   The method for producing ozone water according to claim 1, wherein the catalyst is an alloy composed of silver and palladium.   5. The method for producing ozone water according to claim 4, wherein the catalyst is in a thin film shape, and the thin film catalyst is fixed to the mutually facing surfaces of the plurality of cation exchange membranes.   6. The method for producing ozone water according to claim 5, wherein the thin film catalyst is fixed to the surfaces of the plurality of cation exchange membranes facing each other by sputtering.

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