JPH10130876A - Electrolytic ozonized water producing unit and its regenerating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating an electrolytic ozonized water producing unit when the ozone concn. is lowered and to furnish the electrolytic ozonized water producing unit capable of being appropriately regenerated. SOLUTION: Water is continuously introduced into the electrolytic cell having a high molecular electrolyte membrane 1, an anode 2 and a cathode 3, and a DC voltage is applied between the anode and cathode to produce water from the anode side. When the device is regenerated, an acidic soln. is supplied to the electrolytic cell to clean the membrane 1, anode 2 and cathode 3. Otherwise, deionized water or distilled water is supplied to the anode side, and electrolysis is conducted to regenerate the membrane 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic ozone water producing apparatus for directly producing ozone water in which ozone is dissolved by electrolysis and a method for regenerating the same.

[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, an ozone aeration method in which ozone gas is first generated, mixed with water, and dissolved is known. In order to carry out this method, it is necessary to prepare an ozone gas generation device and an ozone gas / water mixing device.
There are known a method of generating ozone gas by silent discharge using oxygen or air having a high concentration of 0% or more as a raw material, and a method of generating ozone gas by electrolyzing pure water (deionized water). In particular, in the case of pure water electrolysis, 200 g / N
High concentration ozone gas of m ³ or more can be generated.
However, even if a high concentration ozone gas is generated due to the low efficiency of dissolving ozone gas in water, the first problem is that
Only about 0 to 20% can be effectively used, and the remaining ozone gas is generally detoxified by an ozone decomposition catalyst and released into the atmosphere. Further, in the case of a method of generating ozone gas by silent discharge, a source gas generating device such as an air dryer or an oxygen PSA (pressure swing adsorption device) is required.

In such an ozone aeration method in which ozone gas is generated, mixed with water and dissolved, the concentration of ozone water obtained is about 2 to 3 ppm, which is effective for sterilization of Escherichia coli and activation of plants. Even if it is a target, it is not very effective in killing bacteria that are strongly resistant to other antibiotics, and cannot be expected to have a great effect on bleaching and deodorization.

Japanese Patent Application Laid-Open No. 8-134677 discloses an anode electrode 2 made of a noble metal wire mesh having an ozone generation catalytic function on one surface of a polymer electrolyte membrane 1 as shown in FIG.
On the other side, there has been proposed an apparatus for producing high-concentration ozone water by press-contacting cathode electrodes 3 each formed of a wire mesh. According to the above apparatus, ozone water can be produced by directly electrolyzing tap water or the like without the need for an ozone gas / water mixing apparatus or a detoxification treatment of ozone gas, which is industrially desired. It is possible to produce ozone water having a high concentration of 5 ppm or more. However, if the water electrolysis is performed for a long time, the ozone concentration is reduced for the reason described later, and it is necessary to gradually increase the electrolysis current and apply the current between the electrodes.
It was pointed out that ozone water of a satisfactory concentration could not be taken out soon.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and is suitable for a method for regenerating ozone concentration in a conventional electrolytic ozone water producing apparatus when the ozone concentration is reduced, and for the regenerating process. It is an object of the present invention to provide a simple electrolytic ozone water producing apparatus.

[0007]

A method for regenerating an electrolytic ozone water producing apparatus according to the present invention, which achieves the above object, comprises the steps of continuously introducing water into an electrolytic cell having a polymer electrolyte membrane, an anode and a cathode. A method for regenerating an electrolytic ozone water producing apparatus for extracting ozone water from an anode side by applying a DC voltage between an anode and a cathode, wherein the polymer electrolyte membrane is supplied by supplying an acidic solution to the electrolytic cell. And cleaning the anode and the cathode. It is recommended that the acidic solution used for washing the polymer electrolyte membrane, the anode and the cathode be neutralized with an aqueous alkaline solution generated on the cathode side during electrolysis and then drained.

[0008] A second regeneration method of the present invention is characterized in that deionized water or distilled water is supplied to the anode side to perform electrolysis, thereby performing a regeneration treatment of the electrolyte membrane. It is desirable that the above-mentioned deionized water or distilled water be sealed on the anode side, and that electrolysis be performed while passing water on the cathode side, and that the electrolysis be performed at a current density of 0.01 to 0.2 A / cm ² . Further, it is desirable to supply deionized water or distilled water to the anode side and the cathode side, to supply deionized water or distilled water to the anode side, and to supply Ca ²⁺ to the cathode side.
And ion-exchanged water from which divalent ions such as Mg ²⁺ have been removed by cation exchange.

Further, the electrolytic ozone water producing apparatus of the present invention, which achieves the above object, comprises a step of continuously introducing water into an electrolytic cell having a polymer electrolyte membrane, an anode and a cathode, and applying a DC voltage between the anode and the cathode. An electrolysis-type ozone water producing apparatus for extracting ozone water from an anode side by applying a voltage, comprising a cleaning liquid supply means upstream of an electrolytic cell. As the cleaning liquid supply means, a cleaning liquid tank and a feed pump can be used, and an acidic solution may be used as the cleaning liquid.

In the present invention, a supply means for deionized water or distilled water may be provided upstream of the electrolytic cell in place of the cleaning liquid supply means. It is recommended to provide a cation exchange tank in

[0011]

DETAILED DESCRIPTION OF THE INVENTION As raw water used in the water electrolysis method, well water or groundwater may be used in addition to tap water, or highly treated sewage water (so-called hydrophilic,
(Landscape water, medium water, etc.) can be used (hereinafter, these may be collectively referred to as tap water, etc.). In the conventional electrolytic ozone water producing apparatus, as described above, the reason why high-concentration ozone water could not be generated stably for a long time was that the tap water or the like was a so-called hard water component ion such as Ca ²⁺ or Mg ^2+. The hard water component ions are precipitated as hydroxide or carbonate on the cathode side of the electrolyte membrane,
Further, because the hard water component ions accumulate in the electrolyte membrane, which is a cation exchange membrane, the movement of cations from the anode is inhibited. Specifically, the following chemical reactions are performed in the anode, the cathode, and the electrolyte membrane.
As the electrolyte membrane, a polymer solid electrolyte membrane is used, and for example, there is a cation exchange membrane obtained by adding a sulfo group to a Teflon-based polymer membrane. (1) Oxidation reaction at the anode: 3H ₂ O → O ₃ + 6H ⁺ + 6e ⁻ (2) Reduction reaction at the cathode: 2H ⁺ + 2e ⁻ → H Na ⁺ + OH ⁻ → NaOH Ca ²⁺ + 2OH ⁻ → Ca (OH ) ₂ Mg ²⁺ + 2OH ⁻ → Mg (OH) ₂ (3) Accumulation of cations in the electrolytic membrane: R—SO ₃ H + Na ⁺ → R—SO ₃ Na + H
⁺ 2R-SO ₃ H + Ca ²⁺ → (R-SO ₃ ) ₂ Ca + 2
_{^{H + 2R-SO 3 H +}} Mg 2+ → (R-SO 3) 2 Mg + 2
H ⁺

Therefore, it is desirable that tap water and the like introduced into the electrolytic ozone water producing apparatus have hard water component ions such as Ca ²⁺ and Mg ²⁺ removed, and the tap water and the like are introduced into a cation exchanger. By passing through, Ca from tap water etc.
Hard water component ions such as ²⁺ and Mg ²⁺ may be removed. However, when deionized water (pure water), purified water, distilled water, etc., from which almost all ions are removed from tap water or the like, is used, the electric resistance of water becomes 10 μs / cm or less. In the case of the water electrolysis method in which ozone water is generated by supplying deionized water to the anode of the electrolytic cell at a predetermined flow rate,
Electrolysis is required at a very high voltage, and the electrode is significantly consumed, so that generation of ozone water can be maintained for only a short time.

[0013] Hard water component ions such as Ca ²⁺ and Mg ²⁺ can be removed by performing ion exchange using a cation exchange resin or the like. However, since the removal rate is not always 100%, a certain amount of hard water component ions gradually accumulates in the electrolyte membrane if the operation is performed for a long time, and the ozone concentration decreases. Therefore, it is necessary for the electrolytic ozone water producing apparatus to perform a regeneration treatment.

The first invention of the present invention is to wash the hydroxide or carbonate such as Ca and Mg deposited on the cathode side of the electrolyte membrane with an acidic solution, and at the same time, remove the metal ions accumulated in the electrolyte membrane. After removal, the electrolytic ozone water producing apparatus can be regenerated. As the acidic solution used for the cleaning solution, an inorganic acid such as hydrochloric acid may be used,
Alternatively, an organic acid such as acetic acid or citric acid may be used.

For example, by using hydrochloric acid, the precipitates can be removed and the electrolyte membrane can be washed by the following reaction. (i) Removal of precipitate Ca (OH) ₂ + 2HCl → CaCl ₂ + 2H
₂ O Mg (OH) ₂ + 2HCl → MgCl ₂ + 2H
₂ O CaCO ₃ + 2HCl → CaCl ₂ + H
₂ O + CO ₂ MgCO ₃ + 2 HCl → MgCl ₂ + H
₂ O + CO ₂ (ii) Cleaning of electrolyte membrane R'-SO ₃ Na + HCl → R'-SO ₃ H +
NaCl (R′-SO ₃ ) ₂ Ca + 2HCl → 2R′-SO ₃ H
+ CaCl ₂ (R′-SO ₃ ) ₂ Mg + 2HCl → 2R′-SO ₃ H
As the concentration of the + MgCl ₂ acidic solution, for example, when hydrochloric acid is used as the acidic solution, the above-mentioned regeneration treatment can be performed by using a 0.1 to 1N solution.

FIG. 2 is an explanatory view showing a typical example of an electrolytic ozone water producing apparatus suitable for carrying out the regeneration method of the present invention. In FIG. 2, an electrolytic cell comprises a polymer electrolyte membrane 1, anodes 2 and cathodes 3 arranged on both sides thereof, and an anode chamber 2 formed between the polymer electrolyte membrane 1 and the anodes 2 and cathodes 3, respectively.
a and the cathode chamber 3a. A cleaning liquid tank 4 containing a cleaning liquid such as hydrochloric acid as a cleaning liquid supply means.
And a feed pump 5 for supplying a cleaning liquid to the electrolytic cell. Therefore, when the ozone concentration of the ozone water taken out of the anode chamber 2a decreases due to long-term use, the supply flow path of water to the electrolytic cell is closed, and the cleaning liquid is supplied from the cleaning liquid tank 4 by the feed pump 5 to the anode chamber. 2a and the cathode chamber 3a. As shown by the dashed line in FIG. 2, this cleaning liquid flow path can be circulated and used by returning to the cleaning liquid tank 4 after cleaning the electrolytic cell.

As described above, when the regenerating process is repeated by circulating the cleaning solution, the acid concentration is reduced, and the regenerating ability of the cleaning solution is reduced. Therefore, it is necessary to change the cleaning solution periodically or according to the acid concentration. When changing the cleaning solution,
It is recommended that the acid waste liquid be neutralized using an alkaline solution (NaOH) generated on the cathode side along with the generation of ozone water by electrolysis, rendered harmless and disposed of. That is, the wastewater is neutralized with an acidic solution used as a cleaning liquid and an aqueous alkaline solution generated from the cathode side of the electrolytic cell and drained. In this way, by performing the neutralization treatment, it is possible to simultaneously treat the acidic solution required for the regeneration treatment and the alkaline solution by-produced during the production of ozone water.

FIG. 3 is an explanatory view showing an ozone water producing apparatus having a neutralization tank 7 for wastewater treatment for neutralizing the acid waste liquid in addition to the apparatus shown in FIG. The alkaline solution (p) taken out of the cathode chamber 3a during electrolysis
An apparatus configuration is shown in which the acidic solution used for washing the electrolyte membrane and the electrode is neutralized with H9 or more NaOH aqueous solution) to drain water.

FIG. 4 is an explanatory view showing the structure of the apparatus in which two electrolytic cells are arranged in parallel. If the acid cleaning and the generation of ozone water are alternately performed for each system, it is possible to carry out the regeneration processing. Can also take out ozone water and can continuously generate ozone water without interrupting the supply of ozone water.

A second invention according to the present invention is a polymer electrolyte
When removing cations accumulated on the membrane,
H generated on the anode side by electrolysis of water or distilled water⁺ 
(Proton) to regenerate the electrolyte membrane
You. That is, electrolysis is performed by supplying deionized water to the anode chamber.
And by H⁺ Moves the electrolyte membrane from the anode to the cathode.
When it moves, it binds to the ion exchange group of the membrane as shown below.
Ca²⁺, Mg²⁺And Na ⁺ Substituted with cations such as
And push out the accumulated cations to the cathode side. R'-SO_Three Na + H⁺ → R'-SO_Three H +
Na⁺ (R'-SO_Three)_Two Ca + 2H⁺ → 2R'-SO_Three H +
 Ca²⁺ (R'-SO_Three)_Two Mg + 2H⁺ → 2R'-SO_Three H +
 Mg²⁺

Since the raw material water is passed through the cathode side, the cations that have migrated to the cathode side are dissolved in the raw water and removed outside the electrolytic cell, so that the electrolyte membrane can be washed. .

However, in the above-described electrolysis method using deionized water, if the electrolysis is performed under a current density condition (for example, 0.5 A / cm ² or more) that can efficiently generate ozone water, a high potential is applied between the electrodes. It is necessary to apply the voltage, and the consumption of the electrode is accelerated. Therefore, it is desirable that the current density be extremely low compared to the current density at the time of ozone water generation. In other words, the current density (0.01% or more) at which a potential (1.23 V or more) sufficient to generate H ⁺ by electrolysis is obtained.
A / cm ² or more), and the upper limit is 0.2 A
/ Cm ² or less, and preferably 0.1 A / cm ² or less.

Ca ²⁺ and Mg ²⁺ combine with OH ⁻ ions or CO ₃ ²⁻ ions in water to form Ca (OH) ₂ , Ca
This produces compounds such as CO ₃ . Their solubility is low, especially on the alkaline side with a pH above 7.5. Therefore, as the raw material water to be supplied to the cathode side, water having a pH of 7.5 or less is preferable, and a pH of 7 or less is more preferable. Alternatively, it is recommended to use cation-exchanged water or deionized water that does not contain ions such as Ca ²⁺ and Mg ²⁺ to promote the dissolution of the cation compound transferred to the cathode side.

FIG. 5 is an explanatory view showing a typical example of an ozone water producing apparatus for performing a regeneration treatment using deionized water. In the upstream side of the electrolytic cell, a supply path 9a of raw water and a supply flow of deionized water are provided. A road 9b is provided. The deionized water supply channel 9b is
It is branched from the raw water supply passage 9a, and tap water or the like from which iron or silica has been removed by the microfilter 6 is introduced. Reference numeral 11 denotes an ion exchange tank,
⁺ , Ca ²⁺ , Mg ^{2+ and} other cations, Cl ⁻ and CO ₃ ^2-
Are removed. The obtained deionized water is stored in a predetermined amount in a deionized water tank 8 installed at a position higher than the outlet level of the water in the electrolytic cell, and when the electrolytic cell needs to be regenerated, the anolyte 2a is removed. It is configured to be supplied.

FIG. 6 shows that the supply flow path 9b of the deionized water is branched into two flow paths, one flow path being a supply flow path for the raw material water on the anode side, and the other flow path being a flow path for the raw water supply on the cathode side. This is an example in which the deionized water is connected to the supply flow path and deionized water is supplied to both the anode chamber and the cathode chamber.

Also, in the case where the regeneration treatment of the ozone water producing apparatus is carried out using deionized water, as in the case where the regeneration treatment is carried out using the acidic solution, two or more electrolytic tanks are arranged in parallel and deionized. While the regeneration with the ionized water is being performed, the ozone water may be generated by another electrolytic cell so that the supply of the ozone water is not interrupted by the regeneration treatment.

In the present invention, tap water or the like may be supplied to the electrolytic cell because the electrolysis characteristics of the ozone water producing apparatus are restored by performing the regeneration process even if the ozone water concentration is reduced. Hard water component ions such as Ca ²⁺ and Mg ²⁺ can be removed to some extent by ion exchange using a cation exchange resin, and the rate of decrease in ozone concentration can be greatly reduced. Recommended. Reference numeral 10 in FIGS. 5 and 6 denotes a cation exchange tank that incorporates a cation exchange resin and removes hard water component ions.

Specifically, when a cation exchanger such as a cation exchange resin having an SO ₃ ^- group or the like as an ion exchange group is used, hard water components such as Ca ²⁺ and Mg ²⁺ are reacted by the following reaction. Ions can be removed by ion exchange with Na ⁺ ions. Further, since Na ⁺ ions remain in water even after cation exchange, ozone water can be generated without setting the electrolysis voltage high as in deionized water. 2R-SO ₃ Na + Ca ²⁺ → (R-SO ₃ ) ₂ Ca +
_{^{2Na + 2R-SO 3 Na +}} Mg 2+ → (R-SO 3) 2 Mg +
2Na ⁺

However, even if the above-mentioned cation exchange is performed, it is difficult to completely remove hard water component ions such as Ca ²⁺ and Mg ^2+, so that some of them gradually accumulate in the electrolyte membrane. As a result, the ozone concentration decreases. Therefore, the use of the regeneration treatment method of the present invention makes it possible to produce high-concentration ozone water again.

Examples will be described below, but the present invention is not limited to the following examples, and any appropriate changes in the spirit of the foregoing and the following are included in the technical scope of the present invention.

[0031]

Example 1 Ozone water was produced using tap water (only by filtration with a microfilter) by the following constant current electrolysis using a direct electrolysis type ozone water generation apparatus and controlling the current density with respect to the electrolyte membrane constant. An experiment was performed. Ozone water generation: 10 liter / min Electrolytic current density: 0.8 A / cm ² Initial ozone water concentration: 10 mg / liter

The electrolysis performance (electrolysis voltage and ozone water concentration) 10 hours after the generation of the ozone water was measured, the regeneration treatment according to the present invention was performed under the following conditions, and the electrolysis performance after the regeneration treatment was examined. . The results are shown in Table 3. [Regeneration treatment conditions] Cleaning liquid: 0.1 N HCl Circulating amount: 1 liter / min Cleaning time: 60 min

[0033]

[Table 1]

According to the method of the present invention, it can be seen that the electrolytic performance is restored to the initial performance by the regeneration treatment.

Example 2 Ozone water was generated for 10 hours in the same manner as in Example 1, and the electrolysis performance (electrolysis cell voltage and ozone water concentration) at that time was measured. Next, deionized water (ion exchange water)
, Cleaning electrolysis was performed under the following conditions, and the electrolysis performance was examined. The results are shown in Table 4. [Cleaning electrolysis conditions] Electrolysis current density: 0.05 A / cm ² Cleaning time: 30 min

[0036]

[Table 2]

According to the method of the present invention, it can be seen that the electrolysis performance is restored to the initial performance by performing the cleaning electrolysis.

[0038]

Since the present invention is constructed as described above, the present invention provides a regeneration method when the ozone concentration is reduced in the electrolytic ozone water producing apparatus, and an electrolytic ozone water producing apparatus suitable for the regeneration treatment. It can be done.

[Brief description of the drawings]

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

FIG. 2 is a schematic explanatory view showing a typical example of the apparatus of the present invention having a cleaning liquid supply unit.

FIG. 3 is a schematic explanatory view of the device of the present invention having a neutralization tank.

FIG. 4 is a schematic explanatory view of the apparatus of the present invention in which two electrolytic cells are arranged in parallel.

FIG. 5 is a schematic explanatory view showing a typical example of the apparatus of the present invention having deionized water supply means.

FIG. 6 is a schematic explanatory view showing another typical example of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 Anode 3 Cathode 4 Cleaning liquid tank 5 Feed pump 6 Micro filter 7 Neutralization tank 8 Deionized water tank 9a Raw material water supply flow path 9b Deionized water supply flow path 10 Cation exchange resin 11 Ion exchange resin

 ──────────────────────────────────────────────────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 (12)

[Claims] 1. Production of electrolytic ozone water in which ozone water is taken out from the anode side by continuously introducing water into an electrolytic cell having a polymer electrolyte membrane and an anode and a cathode and applying a DC voltage between the anode and the cathode. A method for regenerating an apparatus for producing an electrolytic ozone water producing apparatus, wherein the polymer electrolyte membrane, the anode and the cathode are washed by supplying an acidic solution to the electrolytic cell. 2. The method according to claim 1, wherein the acidic solution used for washing the polymer electrolyte membrane, the anode and the cathode is neutralized by an aqueous alkaline solution generated on the cathode side during the electrolysis and then drained. 3. Production of electrolytic ozone water in which ozone water is taken out from the anode side by continuously introducing water into an electrolytic cell having a polymer electrolyte membrane, an anode and a cathode and applying a DC voltage between the anode and the cathode. A method for regenerating an electrolytic ozone water producing apparatus, comprising supplying deionized water or distilled water to the anode side and performing electrolysis to regenerate the electrolyte membrane. 4. The regeneration method according to claim 3, wherein the deionized water or distilled water is sealed on the anode side, and electrolysis is performed while passing water on the cathode side. 5. The method according to claim 3, wherein the electrolysis is performed at a current density of 0.01 to 0.2 A / cm ² . 6. The regeneration method according to claim 3, wherein deionized water or distilled water is supplied to the anode side and the cathode side. 7. An anode is supplied with deionized water or distilled water, and a cathode is supplied with ion-exchanged water from which divalent ions such as Ca ²⁺ and Mg ²⁺ have been removed by cation exchange. The reproduction method according to claim 6. 8. Production of electrolytic ozone water in which ozone water is taken out from the anode side by continuously introducing water into an electrolytic cell having a polymer electrolyte membrane, an anode and a cathode and applying a DC voltage between the anode and the cathode. An electrolytic ozone water producing apparatus, comprising: a cleaning liquid supply means upstream of an electrolytic cell. 9. The electrolytic ozone water producing apparatus according to claim 8, wherein said cleaning liquid supply means comprises a cleaning liquid tank and a feed pump. 10. The cleaning solution according to claim 8, wherein the cleaning solution is an acidic solution.
Or the electrolytic ozone water producing apparatus according to 9. 11. Production of electrolytic ozone water in which ozone water is taken out from the anode side by continuously introducing water into an electrolytic cell having a polymer electrolyte membrane, an anode and a cathode and applying a DC voltage between the anode and the cathode. An apparatus for producing electrolytic ozone water, comprising: means for supplying deionized water or distilled water upstream of an electrolytic cell. 12. The electrolytic ozone water producing apparatus according to claim 8, wherein a cation exchange tank is provided in a flow path for supplying water to the electrolytic cell.