JPH1121684A - Ozonized water producing device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method dapable of efficiently producing even a dil. ozonized water. SOLUTION: An anode compartment and a cathode compartment are provided through a solid electrolyte membrane, and a water conduit is formed respectively in the anode compartment and cathode compartment. In this ozonized water producing device, an electrode 14 on the anode-compartment side is composed of the electrode segments split in the water flow direction and electrically insulated from one another. Although a current is applied on a part of the anode segments to produce dil. ozonized water, the current is preferably applied only on the segments on the upstream side of the water flow, and the current density is controlled to >=0.5 A/cm<2> in the electrolysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing ozone water, and more particularly, to the production of ozone water in which ozone is dissolved by electrolysis of water, the efficiency of which depends on the target ozone concentration. The present invention relates to an apparatus and a method capable of producing ozone water well.

[0002]

2. Description of the Related Art Since ozone has a strong oxidizing power, it is used in various fields such as sterilization, disinfection, decolorization, deodorization, oxidative decomposition and oxidation treatment, and ozone dissolving ozone. The demand for water is increasing because it is safer and easier to use than ozone gas.

[0003] As a method for producing ozone water, there is known an ozone aeration method in which ozone gas is first generated, and then ozone gas and water are mixed and dissolved. However, since ozone gas has a low dissolving efficiency in water, even if high concentration ozone gas is generated, only about 10 to 20% of the ozone gas can be effectively used, and the remaining ozone gas is harmless by the ozone decomposition catalyst. It is general that it is released into the atmosphere after chemical conversion. Moreover, since the ozone water concentration obtained by the ozone aeration method is about 2-3 ppm, it is effective for disinfecting Escherichia coli and activating plants, but is effective for disinfecting bacteria having strong antibiotics. It is not very effective and cannot be expected to have a great effect on bleaching or deodorization.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 8-134677, an apparatus capable of producing high-concentration ozone water by a water electrolysis method has been developed. As shown in FIG.
The manufacturing apparatus is provided with an anode chamber and a cathode chamber via a solid electrolyte membrane 1, and the anode chamber and the cathode chamber each include an electrode 1 made of a wire mesh.
Lath nets 13, 23 having openings of roughly rhombic shapes
Are sequentially arranged from the solid electrolyte membrane side to form a water passage. In FIG. 1, reference numerals 11 and 21 denote electrode terminals, reference numerals 12 and 22 denote power supply plates, and reference numerals 15 and 2.
5 denotes a jacket, 16 and 26 denote water inlets, and 17 and 27 denote (ozone) water outlets. According to the above apparatus, ozone water can be produced by directly electrolyzing tap water or the like without the need for detoxifying ozone gas, and industrially desired high-concentration ozone water of 5 ppm or more is desired. Can be manufactured.

[0005] However, it is general that an apparatus for producing ozone water is required to produce not only high-concentration ozone water but also low-concentration ozone water. It is known that there is a correlation between the current density during electrolysis and the ozone concentration. To obtain low-concentration ozone water, the current density may be reduced. However, if the current density is set to be low, the efficiency of use of current required for ozone generation is remarkably reduced, and efficient ozone water generation cannot be performed in a wide range of ozone water concentration, leaving room for improvement.

FIG. 2 is a graph showing the relationship between the current density and the ozone water concentration, where the current density is about 0.5 A / cm ^2.
In the above range, it can be seen that the ozone water concentration is almost proportional to the current density. However, the straight line indicating the proportional relationship is not a straight line passing through the origin, and the current density is approximately 0.5 A / cm.
^When it is less than ² , the ozone water concentration becomes extremely low,
At less than A / cm ² , almost no ozone water is generated. Specifically, for example, ozone water having a concentration of 10 mg / L can be obtained at a current density of about 0.8 A / cm ² ,
To obtain ozone water with half the concentration, it is not necessary to halve the current density (0.4 A / cm ² ).
A current density of about three quarters of about 0.6 A / cm ² is required.

FIG. 3 is a graph showing a relationship between electric power consumed for producing 1 g of ozone water (hereinafter referred to as ozone yield) and current density. Low current density conditions (eg,
0.4 A / cm ² , 4 mg / L or less in ozone water concentration)
It can be seen from the graph that the ozone yield becomes extremely large, and the production efficiency of ozone water deteriorates.

As described above, it is possible to obtain low-concentration ozone water by lowering the current density. However, under low current density conditions, the current efficiency at the time of ozone water generation (the current value actually used for ozone generation) / Applied current value) and the production efficiency becomes extremely low.

As a method of producing low-concentration ozone water at a high current density, it is conceivable to increase the amount of water supplied to an ozone water production apparatus. However, since the electrode wire mesh and the lath mesh are tightly packed in the electrolytic cell as shown in FIG. 1, the flow path resistance is high, and the amount of supplied water is limited. If it is adjusted to ozone water, the amount of water supplied when producing high-concentration ozone water must be reduced, and the production efficiency when producing high-concentration ozone water decreases.

Therefore, a method of once producing high-concentration ozone water and diluting it with water to produce low-concentration ozone water has been adopted. However, when water is mixed and diluted, ozone is decomposed. This is not always an efficient method because the concentration of ozone water is reduced below the dilution ratio.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object the purpose of producing ozone water which can be efficiently produced even with low-concentration ozone water. It is an object to provide a manufacturing apparatus and a manufacturing method.

[0012]

An ozone water producing apparatus according to the present invention, which has solved the above-mentioned problems, comprises an anode chamber and a cathode chamber via a solid electrolyte membrane, and the anode chamber and the cathode chamber have water passages respectively. In the apparatus for producing ozone water, the electrode on the anode chamber side is composed of a plurality of electrode segments that are divided in the water flow direction and are electrically insulated from each other, It is preferable that the electrode on the cathode chamber side is also formed of a plurality of electrode segments that are divided in the water flow direction and are electrically insulated from each other.

The ozone water producing apparatus will be described in detail. An anode made of a wire mesh having an ozone generating catalytic function is provided on one side of the solid electrolyte membrane, and a cathode made of a wire mesh is provided on the other side. An electrode is provided, and an anode jacket covering the anode electrode and a cathode jacket covering the cathode electrode are provided on the anode electrode side and the cathode electrode side of the solid electrolyte membrane, and the anode jacket and the cathode jacket, An apparatus for producing ozone water which is provided with an inlet and an outlet, respectively, through which raw water flows in the anode jacket and the cathode jacket, and applies a DC voltage between the anode electrode and the cathode electrode. The ozone water producing apparatus, wherein the anode electrode is composed of a plurality of electrode segments that are divided in a water flow direction and are electrically insulated from each other.

Further, the method for producing ozone water according to the present invention, which has solved the above problems, comprises providing an anode chamber and a cathode chamber via a solid electrolyte membrane, and forming a water passage in each of the anode chamber and the cathode chamber. In producing ozone water using an ozone water production apparatus, the number of anode electrode segments to be energized according to the target concentration of ozone water is divided into a plurality of electrodes in the anode chamber side insulated in the water flow direction. The gist is to make changes. When producing low-concentration ozone water, it is sufficient to energize some of the anode electrode segments, but in this case, it is desirable to energize only the electrode segment on the upstream side in the water flow direction,
It is recommended that electrolysis be performed at a current density of 0.5 A / cm ² or more.

Further, in producing ozone water by supplying electricity only to the anode electrode segment on the upstream side in the water flow direction, after the generation efficiency of ozone water has been reduced by long-term use, the water flow direction in the anode chamber side is reduced. It is desirable to perform the production of ozone water by applying a current to the anode electrode segment on the upstream side in the reversed water flow direction.

[0016]

FIG. 4 is a schematic explanatory view showing a typical example of a manufacturing apparatus according to the present invention. The anode chamber side is divided into two anode electrode segments 10a and 10b. Each anode electrode segment has anode terminals 11a, 11
b, anode feeders 12a and 12b, lath nets (grating made of Ti) 13a and 13b, and noble metal catalysts 14a and 14b, and their respective electrode segments are electrically insulated from each other. Therefore, when producing high-concentration ozone water, use both anode electrode segments, and when producing low-concentration ozone water, use one anode electrode segment to maintain high current density. The electrolysis can be performed as it is. In FIG. 4, 15 is an anode jacket, 16 is an anode-side water inlet,
17 is an ozone water outlet, 21 is a cathode terminal, 22 is a cathode power supply plate, 23 is a lath net (Ti grating), 24 is a catalyst, 25 is a cathode jacket, 26 is a cathode side water inlet, 2
7 denotes a cathode water outlet, and 30 denotes a DC power supply.

The anode side of the DC power supply 30 and the anode side electrode terminal may be connected through an electrical connection means such as a switch. For example, if an electrical switching means such as a magnetic contactor is employed, the anode side may be connected to the anode terminal. Switching between segments is easy.

According to the present invention, if the anode electrode is divided into a plurality of parts in advance in accordance with the target concentration, even if a low-concentration ozone water is produced, the anode electrode has a concentration of 0.5 A / cm ² or more. Since optimal current density conditions can be adopted, low-concentration ozone water can be produced without lowering ozone generation efficiency, and ozone water can be produced with high efficiency over a wide range from low concentration to high concentration. Can be manufactured.

Further, since the anode electrode is divided into a plurality of electrode segments which are electrically insulated from each other and the anode terminals are attached to each of them, the distance between the anode terminal and the tip of the anode power feeder is shortened. Also, a secondary effect that ohmic loss due to electric resistance when current is supplied is reduced can be obtained.

FIG. 5 is a schematic diagram showing an example in which the cathode segment is also divided into two segments on the upstream side and the downstream side.
By energizing only the cathode segment 20a (20b) facing the energized anode segment 10a (10b), the current efficiency is further improved.

When energizing some of the anode electrode segments, it is recommended to energize only the electrode segment on the upstream side in the water flow direction. With respect to the flow direction of the water supplied to the anode side, if electricity is supplied to the electrode segment arranged on the upstream side to generate ozone water by water electrolysis, the downstream side not supplied with electricity is undissolved ozone and water. It functions as a dissolution accelerating unit and can generate higher concentration ozone water. Therefore, the amount of dissolved ozone with respect to the generated ozone is increased, and the efficiency of generating ozone water can be improved.
As shown in FIG. 6, the current-carrying part of the anode electrode is divided into an upstream side, a center part, and a downstream side. The supply water amount is 8 liter / min, the current density is 0.83 A / cm ² , and the current carrying area is 60 cm ^2.
Ozone water was produced under the following conditions. Table 1 shows the ozone water concentration in each case.

[0022]

[Table 1]

It can be seen that the ozone concentration is increased by providing the anode-side conducting section on the upstream side and dissolving and mixing the downstream side, rather than providing the anode-side conducting section at the center or downstream. In other words, by supplying electricity to the anode segment on the upstream side, undissolved ozone can be reduced, and ozone water with less ozone odor can be generated.

As is clear from the graph of FIG. 3, the current density in producing ozone water is preferably 0.5 A / cm ² or more, and 0.7 A / cm ² from the viewpoint of ozone yield.
The above is more preferable. The upper limit of the current density is too high, because the ozone concentration is saturated and the current utilization efficiency is reduced.
0 A / cm ² or less is desirable.

It is to be noted that a noble metal catalyst such as platinum can be used for the anode electrode. However, these catalysts contribute to ozone generation under electrolysis conditions, but when electrolysis is not performed, there is a concern that ozone may be decomposed. Is done. Even if ozone is generated in the upstream anode segment, ozone may be decomposed in the downstream anode segment. Therefore, in the apparatus shown in FIG. 4, a platinum catalyst is used for the anode segment 1 (10a) on the upstream side, and the anode segment 2 (10b) on the downstream side is used.
It was examined whether or not there was a difference in ozone concentration between the case where platinum was used as the catalyst and the case where no catalyst was used. As shown in FIG. 8, the ozone water concentration is higher when the platinum catalyst is provided in the anode segment 2 on the downstream side because the dissolution of ozone is promoted. Therefore, electrolysis is performed only on the upstream side,
It is considered that ozone is not decomposed even if electrolysis is not performed on the downstream side.

By the way, in a polymer electrolyte membrane in contact with a current-carrying electrode, impurities accumulate in the membrane with long-time electrolysis, and it is inevitable that the electrolytic performance deteriorates.
It is possible to recover the performance of the polymer electrolyte membrane to some extent by a regeneration treatment such as washing with an acidic solution. However, it is difficult to recover 100%, and the performance gradually decreases even if the reproduction process is repeated.

Therefore, in the production method of the present invention, in order to efficiently produce low-concentration ozone water, the ozone water production efficiency is reduced by supplying electricity only to the anode electrode segment on the upstream side in the water flow direction to produce ozone water. In the case of a decrease, the current flow is changed to reverse the flow direction of water on the anode side to the downstream side, which functioned as a dissolution promoting section for ozone and water on the anode side. If the electrolyte membrane portion in which no is accumulated is used as the electrolysis portion, it is possible to restore the ozone water generation ability in the initial state.

FIG. 7 shows four anode segments 10a, 1
It is a schematic explanatory drawing which shows the ozone water production apparatus which has Ob, 10c, and 10d, (A) has the structure where the anode terminal is provided in the anode segment 10a, 10b of the water flow direction upstream side, and it is a structure which supplies electricity. It is expected that the electrolytic performance of the upstream portion of the polymer electrolyte membrane will be reduced by long-term use.
In that case, as shown in (B), the raw water is supplied to the ozone water outlet 17 in the case of (A), and
An anode terminal may be provided on each of the anode segments 10c and 10d, and current may be supplied. At this time, the water flow direction on the cathode chamber side may be the same, or as shown in FIG. 7B, may be the opposite direction as on the anode side.

[0029]

As described above, according to the present invention, there can be provided an apparatus and a method for producing ozone water which can efficiently produce ozone water having a low concentration.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a conventional ozone water producing apparatus.

FIG. 2 is a graph showing a relationship between current density and ozone water concentration.

FIG. 3 is a graph showing a relationship between a current density and an ozone yield.

FIG. 4 is a schematic explanatory view showing a representative example of an ozone water producing apparatus according to the present invention.

FIG. 5 is a schematic explanatory diagram showing an example of an ozone water producing apparatus according to the present invention, in which a cathode electrode is also divided.

FIG. 6 is an explanatory view showing a position of a current-carrying part of an anode electrode.

FIG. 7 is a schematic explanatory view showing a typical example of a method for producing ozone water according to the present invention.

FIG. 8 is a graph showing the relationship between the current and the ozone water concentration when a noble metal catalyst is used for the anode segment on the downstream side and when the precious metal catalyst is not used.

[Explanation of symbols]

 11, 21 Electrode terminal 12, 22 Power supply plate 13, 23 Lath net 14, 24 Electrode 15, 25 Jacket 16, 26 Water inlet 17, 27 (Ozone) water outlet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuo Terada 2-3-1, Shinhama, Araimachi, Takasago-shi, Hyogo Inside Kobe Steel, Ltd. Takasago Works

Claims (6)

[Claims] 1. An ozone water producing apparatus comprising: an anode chamber and a cathode chamber provided through a solid electrolyte membrane; and a water passage formed in each of the anode chamber and the cathode chamber. An apparatus for producing ozone water, comprising a plurality of electrode segments divided in a water direction and electrically insulated from each other. 2. The manufacturing apparatus according to claim 1, wherein the electrode on the cathode chamber side is composed of a plurality of electrode segments that are divided in a water flow direction and are electrically insulated from each other. 3. When producing ozone water using an apparatus for producing ozone water in which an anode chamber and a cathode chamber are provided via a solid electrolyte membrane, and a water passage is formed in each of the anode chamber and the cathode chamber, A method for producing ozone water, comprising: dividing an electrode on the anode chamber side into a plurality of pieces insulated in a water-passing direction, and changing the number of anode electrode segments to be energized according to a target concentration of ozone water. 4. The production method according to claim 3, wherein when energizing some of the anode electrode segments, energizing is performed only on the electrode segment on the upstream side in the water flow direction. 5. The method according to claim 3, wherein the electrolysis is performed at a current density of 0.5 A / cm ² or more. 6. When producing ozone water by supplying electricity only to the anode electrode segment on the upstream side in the water flow direction, after the generation efficiency of the ozone water has been reduced over a long period of use, the water flow direction on the anode chamber side is reduced. The production method according to claim 4, wherein the ozone water is produced by supplying electricity to the anode electrode segment on the upstream side in the reversed water flow direction.