JPH11236692A - Electrolytic ozone generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration on the electrode surface after electrolysis is stopped, by intermittently replenishing an anode room by a replenishing device with an electrolytic soln. in a smaller amt. than the consumed amt. of the electrolytic soln. due to the electrolysis and evaporation. SOLUTION: This electrolytic ozone generator 1 has an electrolytic cell equipped with a cathode room 12 having a cathode 6, an anode room 11 having an anode 7 which generates ozone gas, and a solid electrolyte film 13 which separates the cathode room 12 from the anode room 11. Positive potential is applied on the anode 7 through a feeder 14 from a continuous DC supply which continuously supplies a DC current, while negative potential is applied on the cathode 6 through a charge collector 15 to generate ozone. In this process, the anode room 11 is intermittently replenished with an electrolytic soln. 14 from a replenishing device 5 through a flow amt. controlling valve 17. The replenishing amt. of the soln. 14 is smaller than the amt. of the electrolytic soln. consumed by the electrolysis and evaporation when the anode room 11 is filled with the electrolytic soln. 14. Thereby, even after the electrolysis is stopped, a current of reverse electrolysis due to reduction of hydrogen ion can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the production of ozone by electrolysis of water for the purpose of sterilizing and purifying water, washing and sterilizing fresh vegetables, sterilizing and cleaning various contaminants, and surface treatment of industrial materials. The present invention relates to an electrolytic ozone generator provided with a gas generating electrode suitable for the present invention.

[0002]

2. Description of the Related Art There are two methods of generating ozone: a method of oxidizing oxygen in the air into ozone by electric discharge or ultraviolet rays, a method of electrically decomposing water into hydrogen and oxygen, and generating ozone as a by-product. There is. In the method of generating ozone from oxygen in the air, about 80% of nitrogen in the air is oxidized at the same time, so that nitrogen oxides such as nitrogen dioxide and nitrogen monoxide are also generated. At the same time as the production of ozone water, the nitrogen oxides are converted to nitric acid, resulting in strongly acidic ozone water.

[0003] Further, the fact that 80% of nitrogen gas is contained and the oxygen concentration is as low as 20% means that the ozone gas partial pressure in the generated processing gas is low, the amount of ozone dissolved in water is small, and the low concentration of ozone is low. Only ozone water can be produced.

[0004] Therefore, in order to dissolve ozone in water at a high concentration to produce neutral, pure and clean ozone water, a method using water electrolysis is recommended.

[0005] Usually, in order to generate ozone by this electrolysis, an electrolytic cell containing ion-exchanged water is divided into an anode chamber and a cathode chamber by a solid electrolyte membrane, and a porous porous membrane is provided on both sides of the solid electrolyte membrane. A zero-gap electrolytic cell is used in which a positive electrode and a negative electrode are pressed.

The anode chamber has a positive electrode in contact with the electrolyte. The positive electrode is made of porous titanium metal such as a lath material, and β-type lead dioxide is electrodeposited through a platinum plating layer. Use things.

In the cathode chamber, a negative electrode is provided, and a porous metal titanium substrate is subjected to platinum plating similarly to the positive electrode, and a nickel foam or a stainless steel fibrous sheet is used.

The reason why the porous electrode is used is that hydrogen gas generated at the interface between the solid electrolyte membrane and the surface of the negative electrode due to the electrolysis of water in the cathode chamber is sequentially passed through the back surface of the negative electrode and discharged. Similarly, in the anode chamber, water is supplied to the interface between the solid electrolyte membrane and the positive electrode, and oxygen gas and ozone gas generated by the decomposition of water are sequentially passed through the rear surface of the positive electrode and discharged.

Further, the reason why a titanium metal material is selected as the base material of the positive electrode and platinum or lead dioxide is formed on the surface of the electrode substrate is that the surface of the solid electrolyte membrane of the positive electrode becomes strongly acidic and the electrode film in contact with the solid electrolyte membrane becomes strong acid. Naturally, the material must be an acid-resistant material, and the cathode serving as the counter electrode also needs to be relatively acid-resistant. Therefore, a platinum, nickel foam, or stainless steel fibrous sheet is used.

Further, the reason why β-type lead dioxide is selected as the surface treatment of the positive electrode is to generate ozone,
This is because the efficiency of other electrode materials is extremely poor.

Regarding the relationship between the various surface treatment materials of the positive electrode and the ozone generation efficiency, see P.S. C. Foller and C.I. W.
Tobias, J. et al. Electrochem. Soc.
Vol. 129, p. 506, published in 1992 as a relationship between current density and ozone current efficiency.

Usually, a method of surface-treating this β-type lead dioxide on a metallic titanium lath material is to perform anodic deposition by electrodeposition in a lead nitrate plating bath, and the surface treatment of platinum is performed in a platinum salt plating bath. Formed by cathodic deposition.

[0013] However, it is known that in this type of electrolytic ozone generator, when the operation and the stop are sequentially repeated, the ozone production capacity is remarkably reduced.

That is, if the operation is temporarily stopped from a state where a predetermined ozone concentration is obtained by the operation,
When the next operation is restarted, the initial ozone concentration cannot be obtained and it takes time. In addition, the time until a predetermined ozone concentration is obtained is not constant. Generally, if the downtime is long, a considerable operation time is required to secure the amount of ozone generated after the operation is restarted. In addition, the longer the total pause time becomes, the longer the time required to secure this ozone concentration tends to be.

[0015] Further, if the suspension is repeated many times, ozone is finally not generated, and a state in which the ozone concentration does not recover even after a long operation is reached.

The cause is that the hydrogen ions stored in the solid electrolyte membrane during the stop of operation act as a reducing agent on the β-type lead dioxide on the anode surface and react with the oxygen in the lead dioxide to dissolve the lead dioxide. This is because lead dioxide having a β-type crystal structure is transformed into α-type lead dioxide.

That is, the P.S. C. According to a report by Foller et al., Α-type lead dioxide has a ozone generation efficiency of only about 50% as compared with β-type lead dioxide, and is reported to be close to zero on the platinum surface. ,
Dissolution of lead dioxide proceeds, the platinum surface of the underlayer is exposed, and the generation of ozone becomes zero, so that the ozone generation efficiency does not recover even after long operation.

As a method for solving the above problems, as disclosed in Japanese Patent Publication No. 6-76672, a high voltage output terminal for applying a voltage between the positive electrode and the negative electrode during normal operation, By providing a low voltage output terminal for applying a voltage having the same polarity as one third or one half of the terminal voltage, the power supply device can switch between the high voltage output terminal and the low voltage output terminal and connect them. There has been proposed a device in which a low voltage is always applied to each electrode as a backup power source even outside the normal operation time.

By always applying a backup power supply in this way, hydrogen ions can always flow from the positive electrode to the negative electrode in the solid electrolyte membrane, and no reverse current can flow in the electrode surface. It is possible to prevent a change in the crystal structure of the electrode surface of β-type lead dioxide, which is a selective catalyst, and prevent the β-type lead dioxide from dissolving.

[0020]

However, as described in Japanese Patent Publication No. Hei 6-76672, applying a voltage to the constant voltage output terminal outside the normal operation time requires wasteful power. In the event of a power outage or an emergency during maintenance, a backup power supply using a storage battery is further required, and a relatively large storage battery is required to apply a voltage that is low but does not allow reverse current to flow through both electrodes.

For example, to maintain a current of 0.5 A at a voltage of 2.5 V for 24 hours, a storage battery having a capacity of 12 Ah or more is required. A storage battery having a rated capacity of 12 Ah requires a large weight and volume and a compact design. This not only makes it impossible, but also increases the price.

Further, when the battery is stopped for 24 hours or more, the capacity of the storage battery is insufficient, and the positive electrode is deteriorated, so that the ozone generation efficiency must be reduced. That is, energy loss for power storage is large, running costs are uneconomical, and the usability is further restricted.

[0023]

SUMMARY OF THE INVENTION The present invention provides an electrolysis system comprising a cathode chamber having a negative electrode, an anode chamber having a positive electrode serving as an ozone gas generating electrode, and a solid electrolyte membrane separating the cathode chamber and the anode chamber. A DC voltage is applied to the cell, the negative electrode and the positive electrode, and a smaller amount of electrolyte than the amount of electrolyte consumed by electrolysis and evaporation when the anode chamber is filled with electrolyte is intermittently applied to the anode chamber. And a replenishing device for replenishing the water.

Further, as a DC power supply for applying a DC voltage to the negative electrode and the positive electrode, a direct power supply and a backup power supply are provided side by side. When the direct power supply is constantly stopped, the replenishing device is stopped, and the supplied electrolysis is stopped. It has a protection circuit that activates a backup power supply that has the necessary electric capacity for complete consumption of the liquid.It also has a voltage adjustment volume that can adjust the applied DC voltage, and a flow rate that can adjust the amount of electrolyte supplied to the supply device. It has a regulating valve.

Further, the present invention is characterized in that a replenishing device for replenishing the dew water generated by setting the surface of the solid electrolyte membrane in contact with the anode surface of the anode chamber below the dew point temperature of the anode chamber as an electrolyte.

Further, a gas diffusion electrode is used as the negative electrode.

[0027]

DETAILED DESCRIPTION OF THE INVENTION According to the first aspect of the present invention, there is provided a cathode chamber having a negative electrode, an anode chamber having a positive electrode serving as an ozone gas generating electrode, and a solid separating the cathode chamber and the anode chamber. An electrolytic cell composed of an electrolyte membrane, and a DC voltage applied to the negative electrode and the positive electrode, and an amount of the electrolytic solution that is smaller than the amount of the electrolytic solution consumed by electrolysis and evaporation when the anode chamber is filled with the electrolytic solution. Electrolytic ozone generator consisting of a replenishing device for intermittently replenishing the anode chamber with the electrolyte chamber. By intermittently replenishing a deficient amount of the electrolyte, no extra hydrogen ions are formed, and the electrolyte is exhausted. And the resistance increases, the electrolysis current becomes small and the electrolysis stops automatically.Therefore, even after the power is stopped, the current of reverse electrolysis due to the reduction action of hydrogen ions is not generated, and deterioration of the electrode surface is prevented It is what it is.

According to a second aspect of the present invention, a direct-current power supply for applying a direct-current voltage to the negative electrode and the positive electrode is provided with a continuous power supply and a backup power supply. It has a protection circuit that stops and activates a backup power supply that has the electric capacity necessary for complete consumption of the already supplied electrolyte. Even if the directly connected power supply stops after the supply of electrolyte, the backup power supply is used. Of the electrolyte can be consumed by electrolysis, there is no deterioration of the positive electrode surface, and even if the storage battery capacity is relatively small, it is possible to use an inexpensive and small storage battery.

According to a third aspect of the present invention, there is provided a voltage adjusting volume capable of adjusting a DC voltage applied to a positive electrode and a negative electrode, and the amount of ozone generated can be easily controlled by adjusting the DC voltage. Becomes

According to a fourth aspect of the present invention, the replenishing device has a flow rate control valve capable of adjusting the amount of electrolyte supplied, and the amount of electrolysis is determined by adjusting the amount of electrolyte. It can be easily controlled.

According to a fifth aspect of the present invention, there is provided a replenishing device for replenishing the condensed water generated by setting the surface of the solid electrolyte membrane in contact with the anode surface of the anode chamber to the dew point temperature of the anode chamber or lower as an electrolyte. The use of dew water, which is pure water equivalent to distilled water, as an electrolytic solution makes it possible to directly replenish the electrolytic solution from source water containing impurities or from the atmosphere.

According to the sixth aspect of the present invention, the use of a gas diffusion electrode for the negative electrode reduces the generation of hydrogen gas from the cathode chamber, and there is no danger of explosion. Although the cathode surface could not be lowered, the exchange of electric charge in the gas phase allows the electrolytic cell to be installed in a wider range of places and the directionality can be freely determined.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows a configuration diagram of an electrolytic ozone generator 1 according to a first embodiment of the present invention.

The electrolytic ozone generator 1 includes an electrolytic cell 2 for generating ozone by electrolysis of water, a replenishing device 5 for replenishing source water 3 for use as an electrolyte 4 which is ion-exchanged water, and a negative electrode. The power supply 6 includes a direct power supply 8 that constantly supplies a direct current to the positive electrode 7, a backup power supply 9, and a protection circuit 10 that appropriately switches to the backup power supply 9 when the direct power supply 8 stops due to a power failure or the like.

The electrolytic cell 2 has a positive electrode 7 for generating ozone.
And a cathode chamber 12 having a negative electrode 6. The anode chamber 11 and the cathode chamber 12 are separated by a solid electrolyte membrane 13.

The solid electrolyte membrane 13 is a membrane mainly composed of a fluororesin having a sulfonic acid group capable of exchanging hydrogen ions. The solid electrolyte membrane 13 has a hydrogen ion conduction type utilizing the property that hydrogen ions of the sulfonic acid group can freely enter and exit. It has been developed as a solid electrolyte membrane 13.

The solid electrolyte membrane 13 is a polymer having a property of transmitting only hydrogen ions, and is relatively unlikely to conduct or transmit other ions. As the solid electrolyte membrane 13 of the hydrogen ion conductive type membrane used in this example, a solid polymer membrane of N117 sold by DuPont under the trade name of Nafion membrane was used.

The constantly connected power supply 8 is a DC power supply that applies a positive potential to the positive electrode 7 via the power supply 14 and a negative potential to the negative electrode 6 via the current collector 15 during operation.

The replenishing device 5 comprises: an ion exchange resin tower 16 for converting the source water 3 to be used into an electrolytic solution 4 with an ion exchange resin;
A flow control valve 17 for intermittently replenishing the electrolyte 4 into the anode chamber 11.

FIG. 2 shows a positive electrode 7 serving as an ozone generating electrode,
FIG. 3 is an enlarged view of a main part of a zero-gap electrode portion configured by a solid electrolyte membrane 13 and a negative electrode 5 including a gas diffusion electrode 18 and a current collector 15.

The positive electrode 7 uses a porous substrate 19 made of corrosion-resistant titanium metal, and the surface of the substrate 19 is covered with a catalyst layer 20 having an ozone generation selectivity formed by electrodeposition of β-type lead dioxide.

The substrate 19 used for the positive electrode 7 of this embodiment
Is a metal plate porous plate of Tokyo Steel manufactured by sintering chatter vibration-cut short fiber titanium in an oxygen-free atmosphere, and has a porosity of 60 so as to secure an appropriate surface area and prevent clogging in surface treatment performed in post-processing. % And a plate thickness of 2 mm were used.

The cathode 6 was made of a porous mesh having air permeability, and a mixture of a carbon powder and a fluororesin powder carrying ultrafine platinum particles on the surface was press-molded to give a suitable water repellency. It is formed as a joined body of a porous gas diffusion electrode 18 and a current collector 15 that uniformly transmits charges.

The positive electrode 7 and the negative electrode 6 also have a zero-gap electrode configuration in which the hydrogen ion conductive solid electrolyte membrane 7 is interposed and closely attached.

The ion exchange resin tower 16 is connected to a cistern (not shown) containing the source water 3 requiring sterilization by a communication pipe 21. It is installed at a position where water is supplied from the water supply port 22 by the water level adjusting force.

The ion exchange resin tower 16 has a filter A23.
And an ion exchange resin 24 and a filter B25,
The outlet 26 of the ion exchange resin tower 16 is connected to the central opening 27 of the electrolytic cell 2 through the flow control valve 17.

Reference numeral 28 denotes an intake / exhaust mechanism comprising an intake fan 30 attached to an intake port 29 for taking in outside air, and an exhaust port 31 for sequentially feeding outside air containing oxygen to the gas diffusion electrode 18 of the cathode chamber 12. It is.

Reference numeral 32 denotes a discharge port for oxygen gas or ozone gas generated by electrolysis of the anode chamber 11.

The constantly connected electrode 8 is composed of the positive electrode 7 and the negative electrode 6.
In addition, a circuit for applying a DC voltage to and controlling the voltage is built in, and the voltage can be adjusted by a voltage adjustment volume 33. In this embodiment, the positive electrode 7 and the negative electrode 6 of the electrolytic cell 2 are always 3.5 V, and the suction fan 30 is always 5 V.
Was applied.

The protection circuit 10 charges the backup power supply 9 and starts the discharge operation of the backup power supply 9 by the power failure detection relay 34 when the directly connected power supply 8 is stopped. This discharge operation is used to apply a DC voltage to the positive electrode 7 and the negative electrode 6 of the electrolytic cell 2, the flow control valve 17 is closed, and the suction fan 30 is stopped.

The discharging operation is stopped when a decrease in the current value is detected by the DC current value detecting mechanism 35 applied to the positive electrode 7 and the negative electrode 6. In this embodiment, the operation is stopped when the current becomes 0.02 A or less.

Here, the surface treatment step of the positive electrode 3 used in the first embodiment of the present invention will be described.

As a pretreatment, the porous substrate 19 made of a corrosion-resistant metallic titanium material is degreased by ultrasonic cleaning with a 5% surfactant solution, rinsed with ion-exchanged water, and then treated with a 5% oxalic acid solution. It was immersed in boiling water for 5 minutes to remove the oxidized layer on the surface, and immediately before the base treatment, 1N sulfuric acid was used as an electropolishing liquid and electrolytic reduction was performed on the cathode side at 4 A / dm ² .

Immediately after the pretreatment described above, it was immersed in a hydrochloric acid mixed solution in which titanium chloride, tantalum chloride and chloroplatinic acid were each adjusted to a concentration of 0.1 M, and preliminarily dried at 40 ° C. for 15 minutes.
Bake at 520 ° C. This baking base treatment was repeated three times to provide a conductive composite metal oxide base layer 36 of about 1 μm.

Next, the surface to be treated with the underlayer 36 is set to 3 at 4 A / dm ² .
After performing the electrolytic reduction treatment for 0 seconds, electroplating treatment of lead dioxide was performed as the ozone generation selective catalyst layer 20.

In the plating of lead dioxide, first, a saturated lead oxide solution of 3.5N sodium hydroxide was used as a plating bath.
Treatment at 1 A / dm ² on the anode side for 20 minutes formed α-type lead dioxide of several microns. The bath temperature at this time was 40 ° C.

Next, a catalyst layer 20 of β-type lead dioxide, which is an ozone generation-selective catalyst, was formed on the anode in a 1 N nitric acid bath of 30 w% of lead nitrate at 4 A / dm ² for 40 minutes. . The bath temperature at this time was 70 ° C.

In order to improve corrosion resistance and remove distortion, 2 g / L of tantalum oxide is dispersed in a bath and plated to form a tantalum powder 37 in the β-type lead dioxide plating layer.
Is formed.

Further, an adhesive tape was stuck on one side and immersed in a solution of perfluorocarbon sulfanic acid for 1 minute.
After drying at 0 ° C. for 15 minutes, the adhesive tape was peeled off to expose the lead dioxide layer on one side, and the surface-treated resin layer 38 on the opposite side.
The positive electrode 7 is formed by forming.

The operation of the electrolytic ozone generator 1 having the positive electrode 7 according to the first embodiment and the chemical reaction in the electrolytic cell 2 will be described below.

First, when the source water is filled in the cistern, the source water 3 is filled to the P level in the ion exchange resin tower 16 through the water supply port 22 from the communication pipe 21 communicating with the cistern by the water level adjusting force. While the filled source water 3 passes through the filter A23, the ion exchange resin 24, and the filter B25, the metal ions which are the cations contained in the source water 3 are converted into hydrogen ions, and the chloride ions and carbonate ions which are anions. Is ion-exchanged to hydroxyl ions and has an electric conductivity of 2
It becomes ion exchange water of μs or less.

The ion-exchanged water flows as the electrolytic solution 4 from the outlet 26 through the flow control valve 17 through the central opening 27 of the electrolytic cell 2 into the anode chamber 11, and is porous and the same as the gas-permeable feeder 14. The surface of the solid electrolyte membrane 13 is filled through the air-permeable positive electrode 7.

When the electrolyte 4 is filled at the interface between the positive electrode 7 and the solid electrolyte membrane 13, the solid electrolyte membrane 13 absorbs water, activating hydrogen ions of sulfonic acid groups, and the conduction between the negative electrode 6 and the positive electrode 7. And the electrolysis reaction of the electrolytic solution 4 as ion-exchanged water is started at the interface between the positive electrode 7 and the solid electrolyte membrane 13.

The surface material of the positive electrode 7 is β-type lead dioxide, the ozone generation selective catalyst layer 20 having a high corrosion potential and containing reactive oxygen is formed, and the electrode material hardly dissolves.
On the surface of the positive electrode 7, the electrolyte 4 which is ion-exchanged water
The water molecules therein are oxidized, and the reactions of (Chem. 1) to (Chem. 4) occur. Oxygen gas and ozone gas are generated from the surface of the positive electrode 7 mainly from (Chemical Formula 1) and (Chemical Formula 4) from the equilibrium potential of the reaction formula.

Here, if the surface of the plating is made of platinum or the like, the oxygen overvoltage is low and only the reaction shown in (Chem. 1) is performed, and the generation of ozone is small, but the oxygen overvoltage is high and β-type lead dioxide containing reactive oxygen is used. In this case, since the reaction oxygen intervenes as a catalyst in the reaction formula (Chem. 1), the reaction (Chem. 4) is positively generated, the ozone is efficiently generated, and the ozone concentration in the generated gas is high. Become. In the first embodiment,
By applying a DC voltage of 3.5 V and flowing a current of 2 A, an ozone generation amount of about 50 mg / hr was obtained.

[0066]

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[0067]

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[0068]

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[0069]

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[0070]

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Since the electrolytic solution 4 is ion-exchanged water and there is almost no counter ion for hydrogen ions, excess hydrogen ions move to the cathode chamber 12 through the solid electrolyte membrane 13 which is a hydrogen ion conduction type membrane. Therefore, the anode chamber 1
No increase in the hydrogen ion concentration is observed in 1, and the pH maintains the same pH as the source water 3, and if the source water 3 uses purified water and is neutral, the neutrality will be maintained.

Further, the surface of the catalyst layer 20 and the solid electrolyte film 13 of the same type as the fluororesin-based solid electrolyte film 13 coated on the solid electrolyte film 13 side of the catalyst layer 20 of the β-type lead dioxide Hydrogen ions move not only from the surface in contact with the electrolyte membrane 13 but also from the surface of the positive electrode 7 on which the surface-treated resin film 38 is formed, so that the effective area is large and the current density is small even if the current value flowing through the whole is the same. Since the averaging is performed, hydrogen ions can be efficiently transmitted, and local heat generation can be prevented.

Here, if the surface-treated resin film 38 is formed so as to cover the entire surface of the positive electrode 7, the feeder 14 having a platinum surface and the surface-treated resin film 38 come into contact with each other, so that the equilibrium potential is low. 1) The reaction occurs preferentially, and the generation of ozone is suppressed and the efficiency of ozone generation is reduced. However, in the first embodiment of the present invention, since the surface-treated resin film 38 is not formed on the surface of the positive electrode 7 that is in contact with the power supply 14, the reaction of Chemical Formula 1 does not easily occur on the surface of the power supply 14, It does not reduce ozone generation efficiency.

Although a porous titanium substrate having a porosity of 60% was used, the underlayer 36 treatment, the treatment of the ozone generation selective catalyst layer 20 of β-type lead dioxide, and the surface treatment resin film 38 Even if the treatment is performed, passage of oxygen or ozone gas generated from the surface of the positive electrode 7 is not hindered, and the passage is secured.

The cathode 6 in the cathode chamber 12 is constituted by the gas diffusion electrode 18, so that oxygen contained in the outside air sent by the intake / exhaust mechanism 28 and the direct power supply 8
The three components of an electron flowing as a negative potential and a hydrogen ion generated in the anode chamber 11 and passing through the solid electrolyte membrane 13 are interposed, and water is generated by causing a reaction of formula (5). Generate. The generated water is adsorbed on the solid electrolyte membrane 13 or becomes steam and is discharged from the exhaust port 31.

When hydrogen ions generated on the surface of the positive electrode 7 by electrolysis react with oxygen gas on the surface of the negative electrode 6 to be converted into moisture, unreacted hydrogen may remain without sufficiently reacting. There is. Assuming this case, the treatment of hydrogen can be more completely performed by pressing a carbon honeycomb-shaped current collector 15 supporting a platinum catalyst on the surface of the negative electrode 6 opposite to the solid electrolyte membrane 13. is there.

Further, by being attached in close contact with the solid electrolyte membrane 13, oxygen contained in the outside air, electrons carried through the negative electrode 6, and hydrogen ions passing through the solid electrolyte membrane 13 are converted into platinum. When the gas diffusion electrode 18 of the cathode 6 and the solid electrolyte membrane 13 are separated from each other, the movement of hydrogen ions is hindered by the nonconductive gas layer. Not going smoothly,
If the cathode 6 has no through-hole, the cathode 6 itself blocks the movement of oxygen from the surface in contact with the outside air to the solid electrolyte membrane 13, so that a smooth reaction of the three components cannot be achieved.

Further, by using the gas diffusion electrode 18, charges and substances can be exchanged by gas, and even if the surface of the fixed electrolyte membrane 13 of the negative electrode 6 is provided at an upper position, it does not hinder electrolysis at all. .

As described above, a porous mesh-like material having a through hole such as a porous gas diffusion electrode 18 is used as the negative electrode 6, and is attached to the solid electrolyte membrane 13 so as to be close to the air. The generation of moisture by the oxygen fed by the mechanism 28, the hydrogen ions passing from the anode chamber 11 through the solid electrolyte membrane 13, and the electrons carried through the cathode is the generation of hydrogen gas from the surface of the negative electrode 6. And the danger of fire or explosion due to hydrogen gas can be eliminated. In addition, since the cathode chamber 12 does not require an electrolytic solution, purified water, ion-exchanged water, distilled water, pure water, or the like, it is not necessary to manage the treatment of the electrolytic water and control the concentration, and thus the structure of the electrolytic cell 2 is very simple. And the cost of components can be reduced.

In the anode chamber 4, mainly (Chem. 1) and (Chem. 4)
Ozone is produced by the reaction of The ozone gas is taken out from the discharge port 32 and mixed with the source water 3 in the cistern to sterilize the source water 3. In this case, the ozone obtained by the electrolysis method is pure regardless of the conditions of the source water 3, and is almost neutral even when dissolved in water, has little effect on the human body, and the ozone sterilized source water is potable. It is also possible, and drainage will not have a negative impact on the environment.

Anode chamber 1 for electrolyte 4 from replenishing device 5
The amount of supply to 1 can be adjusted by the flow control valve 17. In the first embodiment, 0.1 ml of the electrolytic solution 4 was supplied to the anode chamber 11 for 5 minutes. The DC voltage at that time is 3.5 V, and is initially electrolyzed by a current of 2 A. Electrolyte solution 4 that is electrolyzed in 5 minutes at a current value of 2A
The volume is theoretically 0.06 milliliter or less, but the electrolyte 4 is consumed within 5 minutes because it evaporates from the cathode chamber 12 through the outlet 32 of the anode chamber 11 and the solid electrolyte membrane 13 due to ohmic heat. And lost. When the electrolyte 4 runs out, hydrogen ions, which are the conduction source of the solid electrolyte membrane 13, become insufficient, the resistance increases, and the electrolysis is stopped.

Then, when the electrolyte 4 flows again from the flow control valve 17 of the replenishing device 5, the positive electrode 7 and the solid electrolyte membrane 13
Is satisfied, the conduction of the solid electrolyte membrane 13 is improved, and the decomposition of the electrolytic solution 4 occurs at the interface between the solid electrolyte membrane 13 and the positive electrode 7, and the reaction of (Chem. 1) and (Chem. 4) starts again. Therefore,
Ozone gas is generated in accordance with the supply amount of the electrolytic solution, and is discharged from the discharge port 32.

That is, the amount of ozone generation is determined by the flow rate adjustment of the flow rate control valve 17. In the first embodiment, the ozone generation amount is adjusted to 3.5 V by the voltage adjustment volume 33, and the supply amount of the electrolyte 4 is reduced to 0 in 5 minutes. When the amount was set at 0.1 ml, an ozone generation amount of 20 mg / hr was obtained.

Further, under the same conditions, the replenishment amount of the electrolyte 4 was set to 5
50 mg / min when set to 0.2 ml per minute
The amount of ozone generated is hr, and when set to 0.05 ml, the amount of ozone generated is 10 mg / hr.

As described above, performing the electrolysis by intermittently replenishing the electrolyte 4 that is less than the consumed amount means that if the replenishment of the electrolyte is stopped, the hydrogen ions become insufficient, and the movement of electric charge is eliminated. The resistance of the membrane 13 increases significantly,
Electrolysis is stopped. That is, when the electrolysis is stopped, the hydrogen ions in the solid electrolyte membrane 13 flow backward, and the β-type lead dioxide, which is the catalyst of the ozone generating electrode, does not change or dissolve the crystal structure by reduction, thereby reducing the ozone generation efficiency. There is no promotion.

Further, the ozone concentration can be easily controlled by adjusting the replenishing amount. In combination with the voltage adjustment by the voltage adjusting volume 33, the range of adjusting the ozone generation amount is further greatly expanded.

Next, the primary power supply 39 is not energized,
The operation of the electrolytic ozone generator 1 and the chemical reaction in the electrolytic cell 2 according to the first embodiment when the constantly connected power supply 8 is stopped will be described.

When the primary power supply 39 of the electrolytic ozone generator 1 cannot be energized due to a power outage or maintenance,
The operation of the backup power supply 9 is started by the power failure detection relay 34 of the protection circuit 10. The protection circuit 10 closes the flow control valve and stops the suction fan. At this time, the backup power supply 9 is normally charged by the direct power supply 8.

That is, a DC voltage of 3.5 V is continuously applied from the backup power source 9 to the positive electrode 7 and the negative electrode 6 of the electrolytic cell 2, and a current of 2 A flows at the beginning.
However, the amount of the electrolyte 4 already supplied is 0.1 ml or less, and within 5 minutes, the residue of the electrolyte 4 attached to the positive electrode 7 is decomposed and hydrogen ions accumulated in the solid electrolyte membrane 13 are decomposed. Is consumed, the amount of charge transfer material between the positive electrode 7 and the negative electrode 6 decreases, and the electrolytic resistance increases.
As a result, the current values of the positive electrode 7 and the negative electrode 6 decrease, and the electrolysis is stopped.

Here, since the flow regulating valve 46 is kept closed, there is no replenishment of the new electrolyte 4 and the stop state is continued.

When the current value between the positive electrode 7 and the negative electrode 6 becomes equal to or less than a predetermined value, the DC current value detection mechanism 35 operates, the discharge operation is stopped, and the application of the voltage between the positive electrode 7 and the negative electrode 6 is stopped. I do.

In the first embodiment, the current value is 0.0
The detection mechanism 43 is set to start when the pressure becomes 2 A or less.

As described in the conventional example, when β-type lead dioxide having ozone generation selectivity is used as the catalyst layer 20 of the positive electrode 7, when the electrolysis is stopped in the presence of the electrolytic solution, a reduction action is performed. Ozone generation efficiency decreases due to the reaction with oxygen of lead oxide and the elution of lead or the change of β-type crystal structure to α-type due to the presence of hydrogen ions, but as described above, the backup power supply When the electrode 9 is activated, the electrolyte 4 that allows the positive electrode 7 and the solid electrolyte membrane 13 to conduct with each other.
Is consumed in a short time, no reverse current is generated even in the event of an abnormality such as a power failure, the anode surface is not deteriorated, and the ozone generation efficiency is maintained.

In the first embodiment, a storage battery having a current capacity of 2.5 A is selected for 30 minutes just in case. However, a storage battery having a capacity of 1.25 Ah can be used, and it is very compact and low in capacity. Priced storage batteries were selected. Further, even if the stop was continued for a long time, there was almost no deterioration of the electrode surface.

In order to increase the adhesion between the corrosion-resistant metal substrate 19 and the β-type lead dioxide, platinum was used as the binding metal. However, palladium may be used, and these are the most common surface treatment agents. It is selected in consideration of effects on living organisms and disposal pollution, and other gold and platinum group metals such as ruthenium, rhodium, osmium and iridium may be used.

In this embodiment, lead dioxide is used as the catalyst layer 20, but it is the most efficient in terms of ozone generation efficiency, but in consideration of toxicity and the like, tin dioxide, ferrite, etc. And a mixture of platinum and titanium oxide are also possible and are not limited to lead dioxide.

Although the gas diffusion electrode 18 is used as the negative electrode 6 of the cathode chamber 12, hydrogen generated by electrolysis of water which has a risk of explosion can be replaced with water, and the degree of freedom in mounting the electrolytic cell 2 is increased. This is advantageous in that safety can be improved and the influence of moisture on the solid electrolyte membrane 13 can be reduced when the backup power supply 9 is operated in the protection circuit 10. However, even if the gas diffusion electrode 18 is not used, stainless steel or the like can be used. It is also possible to use a method in which the negative electrode 6 is formed of a metal, water is interposed in the cathode chamber 12, hydrogen gas is generated, and the hydrogen gas is separately burned in post-processing.

(Embodiment 2) FIG. 3 shows a configuration diagram of an electrolytic ozone generator 40 according to a second embodiment of the present invention.

The electrolytic ozone generator 40 includes an electrolytic cell 41 for generating ozone by electrolysis, a replenishing device 42 for replenishing the electrolytic solution 4, a negative electrode 6 and a positive electrode 7, as in the first embodiment. Always directly connected power supply 8 that always supplies DC current
And a backup power supply 9 and a power supply 8 which is always directly connected due to a power failure or the like
And a protection circuit 10 that switches to the backup power supply 9 appropriately when stopped. However, in FIG. 3, the constantly connected power supply 8, the backup power supply 9, and the protection circuit 10 are omitted because they are the same as those in the first embodiment.

The electrolytic cell 41 comprises an anode chamber 11 having a positive electrode 7 for generating ozone and a cathode chamber 12 having a negative electrode 6. The anode chamber 11 and the cathode chamber 12 are formed by a solid electrolyte membrane 13. It is partitioned.

The materials and manufacturing methods of the solid electrolyte membrane 13, the positive electrode 7, and the negative electrode 6 are the same as those in the first embodiment, and the description is omitted.

The cathode chamber 12 is composed of a current collector 15, a negative electrode 6 serving as a gas diffusion electrode 18, and a solid electrolyte membrane 13. A thermoelectric element 43 is mounted on the back of the current collector 15.
The solid electrolyte membrane 13 is cooled through the negative electrode 6.

The replenishing device 42 for the electrolytic solution 4 comprises a boiler chamber 44 containing the source water 3, a heater 45 and a flow control valve 46 for guiding steam. The boiler chamber 44 and the anode chamber 11 are connected to a flow control valve. It is connected at 46.

Further, the positive electrode 7 and the negative electrode 6 have a zero-gap electrode configuration in which the solid electrolyte membrane 13 of the hydrogen ion conduction type is interposed therebetween and closely attached thereto.

Reference numeral 47 denotes a suction / exhaust mechanism comprising a suction pump 49 attached to a suction port 48 for sucking outside air, and an exhaust port 50 for sequentially feeding outside air containing oxygen to the gas diffusion electrode 18 of the cathode chamber 12. It is.

Reference numeral 32 denotes a discharge port for oxygen gas or ozone gas generated by the electrolytic reaction of the electrolytic solution 4 in the anode chamber 11.

The operation of the electrolytic ozone generator 40 and the chemical reaction in the electrolytic cell 41 according to the second embodiment will be described below.

First, the source water 3 in the boiler chamber 44 is heated by the heater 45. A part of the heated source water 3 becomes steam and moves to the anode chamber 11 which is indirectly cooled by the thermoelectric element 43 of the cathode chamber 12. The transferred vapor reaches the surface of the solid electrolyte membrane 13 through the gas-permeable power supply 14 and the porous and similarly gas-permeable positive electrode 7. Since the solid electrolyte membrane 13 is cooled by the thermoelectric element 43 from the cathode chamber 12 side to a temperature lower than the dew point of the anode chamber 11 in particular, dew condensation starts on the surface of the solid electrolyte membrane 13. The condensed water is adsorbed on the solid electrolyte membrane 13 and activates the hydrogen ions of the sulfonic acid group, so that the conduction between the negative electrode 6 and the positive electrode 7 is improved. Condensation continues at the interface between the positive electrode 7 and the solid electrolyte membrane 13, and the electrolytic reaction is started with the condensed water as the electrolyte 4.

Therefore, as in the first embodiment, the surface material of the positive electrode 7 is β-type lead dioxide, and the ozone generation selective catalyst layer 20 having a high corrosion potential and containing reactive oxygen is formed. The electrode material hardly dissolves, and on the surface of the positive electrode 7, dew condensation oxidizes water molecules that have become the electrolytic solution 4,
The reactions of (Chem. 1) to (Chem. 4) occur. Oxygen gas and ozone gas are generated from the surface of the positive electrode 7 mainly from (Chemical Formula 1) and (Chemical Formula 4) from the equilibrium potential of the reaction formula.

Here, if the surface of the plating is made of platinum or the like, the oxygen overvoltage is low and only the reaction of (Chem. 1) is performed, and the generation of ozone is small, but the oxygen generation potential is high and β containing reactive oxygen is used.
In the case of lead dioxide of the type, the reaction oxygen (Chem. 4) is positively generated because the reaction oxygen intervenes as a catalytic action in the reaction formula (Chem. 1), so that ozone is efficiently generated and Ozone concentration increases.

The source water was heated to 40 ° C.
° C so that it is always 3.5
When V was applied, a current of 2 A flowed, and an ozone generation amount of about 50 mg / hr was obtained.

Since there is almost no counter ion of hydrogen ions in the electrolytic solution 4 of the condensed water, excess hydrogen ions move to the cathode chamber 12 through the solid electrolyte membrane 13 which is a hydrogen ion conductive membrane. Therefore, no increase in the hydrogen ion concentration is observed in the anode chamber 11, the pH is kept as distilled water, the same pH as the source water 3 is maintained, and if the source water 3 uses purified water and is neutral, the pH is neutral. Nature will be maintained.

The function of the surface-treated resin film is the same as that of the first embodiment. Local heat generation can be prevented, and a surface-treated resin film 38 is formed on the surface of the positive electrode 7 that comes into contact with the power supply 14. Therefore, on the surface of the feeder 14,
Does not easily occur, and does not lower the ozone generation efficiency.

On the surface of the negative electrode 6 in the cathode chamber 12, oxygen contained in the outside air sent by the intake / exhaust mechanism 28, electrons flowing as a negative potential of the direct power supply 8, and generated in the anode chamber 11. Thus, three components with hydrogen ions passing through the solid electrolyte membrane 13 intervene to generate water by causing the reaction of (Chem. 5).

The supply amount of the electrolytic solution 4 varies depending on the heating temperature of the source water 3 by the heater 45 and the dew point temperature of the surface of the solid electrolyte membrane 13 cooled by the thermoelectric element 43, and intermittently opens the flow control valve 46. It can be adjusted according to the opening time.

The amount of ozone generated is determined by the amount of replenishment and the voltage applied to the negative electrode 6 and the positive electrode 7. If the heating temperature of the source water 3 and the dew point temperature of the solid electrolyte membrane 13 are constant,
As in the first embodiment, it is determined by adjusting the voltage adjustment volume 33 and the flow adjustment valve 46.

In this embodiment, the source waters 3 and 10 at 40 ° C.
When the applied voltage was set to 3.5 V with the voltage adjustment volume 33 under the dew point temperature condition of ° C., about 20 mg / hr of ozone was generated by opening the flow adjustment valve 46 for 5 minutes in 10 minutes.

In the second embodiment, the replenishing device 4 for the electrolytic solution 4 is used.
When the gas diffusion electrode 18 is used for the negative electrode 6, both the electrodes are mass-transferred by gas. However, there is an advantage in that the electrolytic solution 4 can be obtained directly from the source water 3. However, the effect of preventing the ozone generation efficiency from being lowered when the electrolysis is stopped, and the fact that the backup power supply 9 The effect of selecting a capacitor having a small capacity and reducing the cost is the same as that of the first embodiment.

[0119]

As described above, the electrolytic ozone generating apparatus according to the present invention comprises a cathode chamber having a negative electrode, an anode chamber having a positive electrode which is an ozone gas generating electrode, and a solid compartment separating the cathode chamber and the anode chamber. An electrolytic cell composed of an electrolyte membrane, and a DC voltage applied to the negative electrode and the positive electrode, and an amount of the electrolytic solution that is smaller than the amount of the electrolytic solution consumed by electrolysis and evaporation when the anode chamber is filled with the electrolytic solution. Electrolytic ozone generator consisting of a replenishing device for intermittently replenishing the anode chamber with the electrolyte chamber. By intermittently replenishing a deficient amount of electrolyte, no excess hydrogen ions are formed, and the electrolyte runs out. And the resistance becomes large, the electrolysis current becomes minute and the electrolysis stops automatically, so even after the power is stopped, the current of reverse electrolysis due to the reduction action of hydrogen ions does not occur,
It is possible to prevent deterioration of the electrode surface.

Further, a DC power supply for applying a DC voltage to the negative electrode and the positive electrode is provided with a continuous power supply and a backup power supply. It has a protection circuit that activates a backup power supply that has the necessary electric capacity for complete consumption of the electrolyte. It can be consumed, there is no deterioration of the positive electrode surface, and the storage battery capacity can be relatively small, and a small storage battery can be selected.

Further, it has a voltage adjusting volume which can adjust the DC voltage applied to the positive electrode and the negative electrode, and the amount of ozone generation can be easily controlled by adjusting the DC voltage.

Further, the replenishing device is provided with a flow rate regulating valve capable of adjusting the replenishing amount of the electrolytic solution. By adjusting the amount of the electrolytic solution, the amount of electrolysis is determined, and the amount of ozone generated can be easily controlled.

Further, the present invention is characterized by a replenishing device for replenishing dew water generated by setting the surface of the solid electrolyte membrane in contact with the anode surface of the anode chamber below the dew point temperature of the anode chamber as an electrolyte. The use of dew water, which has become pure water equivalent to water, makes it possible to replenish the electrolyte from source water containing impurities and also from the atmosphere.

Further, by using a gas diffusion electrode for the negative electrode, the generation of hydrogen gas from the cathode chamber is reduced, and there is no danger of explosion. In addition, when an aqueous solution is used, the cathode surface is lowered. However, since the exchange of electric charges in the gas phase becomes possible, the degree of freedom of the installation place of the electrolytic cell is expanded, and the direction can be freely determined.

[Brief description of the drawings]

FIG. 1 is a schematic view of an electrolytic ozone generator according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of a junction between a positive electrode, a solid electrolyte membrane, and a negative electrode according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram of an electrolytic ozone generator according to the first embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1,40 electrolytic ozone generator 2,41 electrolytic cell 4 electrolytic solution 5,42 replenisher 6 negative electrode 7 positive electrode 8 continuous power supply 9 backup power supply 10 protection circuit 11 anode chamber 12 cathode chamber 13 solid electrolyte membrane 17,46 Flow control valve 18 Gas diffusion electrode 33 Voltage control volume

Claims (6)

[Claims] 1. An electrolytic cell comprising: a cathode chamber having a negative electrode; an anode chamber having a positive electrode serving as an ozone gas generating electrode; a solid electrolyte membrane separating the cathode chamber and the anode chamber; A replenishing device for intermittently replenishing the anode chamber with a smaller amount of electrolyte than the amount of electrolyte consumed by electrolysis and evaporation when a predetermined DC voltage is applied to the electrodes and the anode chamber is filled with the electrolyte. Electrolytic ozone generator. 2. A direct-current power supply and a backup power supply are provided side by side as a DC power supply for applying a DC voltage to the negative electrode and the positive electrode. The electrolytic ozone generator according to claim 1, further comprising a protection circuit that operates a backup power supply having an electric capacity necessary for complete consumption of the electrolyte. 3. The electrolytic ozone generator according to claim 1, further comprising a voltage adjusting volume for adjusting a DC voltage applied to the positive electrode and the negative electrode. 4. The electrolytic ozone generator according to claim 1, wherein the replenishing device has a flow control valve capable of adjusting a replenishing amount of the electrolytic solution. 5. A replenishing device for replenishing dew water generated by setting a surface of a solid electrolyte membrane in contact with a positive electrode surface of an anode chamber to a temperature equal to or lower than a dew point temperature of an anode chamber as an electrolyte. Item 4. The electrolytic ozone generator according to any one of Items 3. 6. The electrolytic ozone generator according to claim 1, wherein a gas diffusion electrode is used as the negative electrode.