JP3210688B2 - Aeration method for ozone-containing gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the production of ozone water by efficiently dissolving an ozone-containing gas generated by a water electrolysis reaction in water or to the ozone treatment for directly ozone-treating water with the ozone-containing gas. The present invention relates to a method for diffusing a contained gas, a filter used for the method, and a method for producing the same.

[0002]

2. Description of the Related Art Ozone is attracting attention as a strong and clean oxidizing agent, and its decomposition product is oxygen, and its residue is more susceptible to oxidation than conventional chlorine-based oxidizing agents. The use for water treatment is increasing because it does not remain in treated water, the decomposition rate is high, ozone does not remain itself, and there is no problem of secondary pollution. As described above, the discharge method and the electrolysis method have been mainly used to generate an ozone-containing gas containing ozone that is useful as an oxidizing agent, but the electrolysis method is currently the mainstream due to the purity of the product and the ease of operation. It has become. To perform water treatment or the like using the ozone-containing gas generated by this electrolysis method, ozone water obtained in a gas-liquid mixed state is directly contacted with the water to be treated, or the water to be treated is placed in the anode chamber of the electrolytic cell. Although it is directly fed and brought into contact with ozone, the former has poor contact efficiency with the water to be treated because ozone is present in the form of bubbles, and electrode substances and the like are mixed in the ozone water generated in the electrolytic cell and the substance is damaged. The treated water may be contaminated, and in the latter case, there is a problem that the electrode is contaminated by impurities in the treated water.

Therefore, in many cases, an ozone-containing gas generated in the anode chamber of an electrolytic cell in a gas-liquid mixed state is once supplied to a mixing tank or the like through, for example, a diffuser filter to remove impurities, and the filter removes the impurities. The ozone-containing gas in a gas-liquid mixed state is diffused into the mixing tank to dissolve ozone almost completely in the water in the mixing tank to generate gaseous ozone-free uniform concentration ozone water. For ozone treatment of the water to be treated. A filler (a dashing or the like) formed of a corrosion-resistant material has been used as the filter, but the dashing does not sufficiently disperse the ozone, and a sufficiently high-concentration ozone water useful for a sterilization treatment of the water to be treated. Could not be manufactured. In order to solve this problem and to effectively use ozone generated by electrolysis to produce high-concentration ozone water, the present applicant has proposed the use of a filter made of a sintered body of titanium short fibers (Japanese Patent Application Hei 1-293092). The titanium short fiber sintered filter has relatively fine and irregular eyes because the fibers are entangled. Can be manufactured. However, since the filter is manufactured by a process of sintering by tangling titanium short fibers, there is a limit to the fineness of the eyes, and the ozone-containing gas cannot be more favorably dispersed in water. There is also a limit on the concentration of ozone water. Also, if the fiber diameter is reduced to reduce the diffusing pores, the short fibers themselves may partially burn when sintering the short fibers, and it is not possible to reduce the diffusing pores to a certain degree or more. Obtaining ozone water can be difficult.

[0004]

An object of the present invention is to eliminate the above-mentioned drawbacks of the filter for dissolving ozone and to produce ozone water having a sufficiently high concentration or to disperse an ozone-containing gas in the water to be treated and ozone-treat the water to be treated. It is an object of the present invention to provide a method capable of carrying out the method, a diffuser filter usable in the method, and a method for producing the same.

[0005]

According to the present invention, an ozone-containing gas is generated in an anode chamber of an electrolytic cell by electrolyzing water, and the gas is mixed in a gas-liquid state to form a large number of fine diffused pores. And supplying the ozone-containing gas through the filter into the mixing tank and dissolving the ozone-containing gas in the water in the mixing tank. The filter that can be used in the method is a method in which a fluorinated monomer to which a substance that generates gas by heating or acid treatment is polymerized to produce a fluororesin, and heated by or during the polymerization. Alternatively, it can be manufactured by forming a large number of fine diffused holes in the fluororesin by gas generation by acid treatment.

Hereinafter, the present invention will be described in detail. The method for diffusing ozone-containing gas according to the present invention is characterized in that a filter made of fluororesin having a large number of fine diffusing holes is used as a diffusing filter. This filter may be manufactured by sintering a fibrous fluororesin, and even if this method is employed, since the fluororesin has good heat resistance, it does not burn, unlike titanium short fiber. .
However, in order to obtain a filter having finer air diffusion pores, a substance which generates gas by a small amount of heating or acid treatment, such as calcium carbonate, was added to a fluorine resin monomer before polymerization, that is, a fluorine-containing monomer such as tetrafluoroethylene. Thereafter, the mixture is polymerized to form a fluororesin filter having a predetermined shape. When calcium carbonate is added as the gas generating substance, at least a part of the calcium carbonate is decomposed into calcium oxide and carbon dioxide due to heat at the time of monomer polymerization, and the carbon dioxide is scattered outside the system as a gas and scattered to that part. Pores are formed. When the number of the diffused pores is insufficient, heating is further performed, or in the case of a substance which is decomposed by the acid treatment to generate gas, an acid treatment is performed to form a desired diffused pore.

[0007] The pore diameter of the diffused pores formed by the gas generation method is usually considerably smaller than the pore diameter of the diffused pores formed by sintering of the fibrous substance, and is generally 0.1 to 20 µm. Of course, the fluororesin diffuser filter of the present invention may be manufactured by sintering a fibrous fluororesin, and the pore size of the diffuser holes of the filter thus produced is larger than the pore size of the filter produced by the gas generation method. Is large, but it is possible to diffuse the ozone-containing gas relatively favorably. The fluororesin in the present invention is not only polytetrafluoroethylene (trade name: Teflon) produced by polymerizing tetrafluoroethylene, but also hydrogen-containing produced by polymerization of a monomer containing hydrogen and fluorine or by copolymerization thereof. Also includes fluororesin.

In the case where the fluororesin is hydrophobic and the surface of the air diffusion filter formed of the fluororesin becomes hydrophobic, the ozone-containing gas permeating through the air diffusion holes is not sufficiently dispersed and becomes foamy. There is. In that case, the surface of the filter may be subjected to a hydrophilic treatment to sufficiently disperse the ozone-containing gas, and the hydrophilic treatment may be performed by coating a solution of a hydrophilic material and drying the material, or by sputtering the hydrophilic material. There is a method of directly coating the filter surface. The filter thus formed becomes a three-dimensional network, and the diffused pores are formed irregularly in the network, so that the ozone-containing gas in a gas-liquid mixed state flowing in the filter generates an irregular flow. As a result, the air diffuses out of the filter in an irregular state, so that the diffused state is very good.Therefore, it is sufficiently dispersed in the mixing tank or the like where the filter is installed, so that the solubility is increased and a high concentration ozone water can be obtained. ,
Alternatively, the ozone treatment can be performed by sufficiently contacting the water to be treated existing in the mixing tank or the like. Depending on other conditions, the use of a conventional dashing or sintered titanium short fiber filter results in an ozone concentration of about 5
ppm and about 20 ppm of ozone water can be obtained, while using the fluororesin filter of the present invention,
Ozone water of 30 ppm or more can be obtained.

Since the air diffusion filter of the present invention is made of fluororesin, it has resistance to the oxidizing power of ozone, is chemically and physically stable, and does not dissolve in ozone water. No adverse effect on human body. This filter is installed, for example, in a mixing tank so as to be in contact with the raw water for ozone water production or the water to be treated requiring ozone treatment, and a gas-liquid mixed ozone-containing gas generated by a normal electrolytic method is connected to a conduit or the like. And high-concentration ozone water is generated as described above by passing through the filter provided in the mixing tank, or ozone treatment of the water to be treated is favorably performed. Further, the filter of the present invention has a filtering function similar to a conventional filter, and can efficiently remove, for example, an electrode substance or the like which may be mixed into an ozone-containing gas in a gas-liquid mixed state supplied to a mixing tank. . Depending on the installation position of the fluororesin filter of the present invention in the mixing tank, the raw water for the ozone water production or the water to be supplied supplied to the mixing tank is in direct contact with the filter to remove the ozone-containing gas in the filter. May hinder distribution. In such a case, the surface in contact with the raw material water or the like may be coated with a fluororesin sheet or the like.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a process for producing ozone-rich water and ozonation of water to be treated according to the present invention. However, the examples do not limit the present invention. Example FIG. 1 is a flowchart showing a system for producing high-concentration ozone water by the method for diffusing ozone-containing gas according to the present invention. Ozone water was produced using this system under the following conditions. An electrolytic cell (electrolytic ozonizer) 1 having an effective electrolysis area of 90 cm ² and lead dioxide powder 3 on the anode surface
An SPE type electrolytic cell was prepared by mounting a membrane 2 made of Nafion (trade name), which is a solid electrolyte having platinum powder 4 adhered to the cathode surface, and the electrolytic cell 1 was filled with 1 liter of pure water.
By supplying electricity to the electrolytic cell 1 so as to have a current density of 100 A / dm ² , a mixed gas of ozone and oxygen (ozone-containing gas) containing about 15% by weight of ozone was supplied at 27 g / hour (30 g / hour).
At 20 ° C. (about 20 l / h) (ozone 4 g / h).

13 g of tetrafluoroethylene to which 3 g of calcium carbonate has been added is dissolved in solvent naphtha,
The polymerization was carried out while heating to ~ 400 ° C. The obtained fluororesin was molded into a disk shape having a diameter of 10 cm and a thickness of 1 mm to form a fluororesin diffuser filter 8, and this filter 8 was installed at the bottom of the mixing tank 9. In addition, the pore diameter of the aeration holes of the filter 8 was 1 to 5 μm. The ozone-containing gas is supplied from the anode chamber 5 through the conduit 7 to the mixing tank 9 from below, passes through the filter 8 and is dispersed to be dissolved in the water in the mixing tank 9. From 10 released to the atmosphere. The ozone concentration of the ozone water generated in the mixing tank was maintained in the range of 20 to 30 ppm. On the other hand, pure water at 25 ° C. is used as the water to be treated, and the water to be treated is supplied to the ultrapure water production line at 1 m ³ / hour, and 30% of the whole water to be treated is branched by the branch pipe 11. Then, the water was supplied from above to the mixing tank 9 and brought into contact with the ozone water in the mixing tank 9 to oxidize the water to be treated. The water to be subjected to branch treatment in which ozone was dissolved was supplied to the reaction tank 13 together with the water to be treated which was not branched by the pump 12, and all the water to be treated was treated with ozone. The ozone concentration in the ozone water at the outlet of the mixing tank is 12.7p
pm, and the ozone concentration at the outlet 10 was 5000 ppm. The ozone concentration in the water to be treated in the reaction tank 13 was 3.8 ppm.

Comparative Example Instead of a fluororesin filter, a commercially available diameter of about 30 μm was used.
Production of ozone water and ozone treatment of water to be treated were similarly performed using a titanium filter formed by sintering titanium short fibers of the above. The diameter of the air diffusion holes of this titanium filter was 30 to 50 μm. The ozone concentration of the ozone water generated in the mixing tank is maintained in the range of 15 to 20 ppm, the ozone concentration in the ozone water at the outlet of the mixing tank is 11 ppm, and the outlet is
The ozone concentration of No. 10 was 1500 ppm, and the ozone concentration of the water to be treated in the reaction tank 13 was 3.4 ppm.

[0013]

According to the method for diffusing ozone-containing gas according to the present invention, the ozone-containing gas generated by the electrolysis method is mixed in a gas-liquid mixed state by installing a fluororesin filter having a large number of fine diffused pores. The mixture is supplied to a tank, and the ozone-containing gas is diffused through the filter into the mixing tank and dissolved in water in the mixing tank. Since this fluororesin filter has finer and irregular air holes than a titanium filter or the like, the ozone-containing gas is smoothly dispersed in the water in the mixing tank to generate high-concentration ozone water, or Ozone treatment can be performed. The fluororesin filter according to the present invention is formed with a large number of fine diffused pores and has, for example, a higher resistance to sintering than a titanium filter, so that the fluororesin filter produced by the sintering method contains more ozone than the titanium filter. It can highly disperse gas and is suitable for production of high concentration ozone water and ozone treatment of water to be treated.

Fluororesin filters are highly hydrophobic,
The ozone-containing gas that has passed through the filter may be foamed. In such a case, the ozone-containing gas is improved by applying a hydrophilic substance such as a metal compound by coating or sputtering to improve the hydrophilic property. Can be sufficiently dispersed. The fluororesin filter of the present invention can also be produced by polymerizing a fluorinated monomer to which a substance that generates gas by heating or acid treatment is added, and the filter thus produced is extremely small due to the gas generation. When air diffusion holes are formed and the filter is used for diffusing ozone-containing gas, the dispersion of ozone-containing gas is much better than conventional filters, and the production of high-concentration ozone water and effective Ozonation can be achieved.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing an example of a process for producing ozone water and treating treated water by an ozone-containing gas diffusion method according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrolysis tank 2 ... Diaphragm 3 ... Lead dioxide powder 4 ... Platinum powder 5 ... Anode chamber 6 ... Cathode chamber
7 ... conduit 8 ... filter 9 ... mixing tank
10 ・ ・ ・ Discharge port 11 ・ ・ ・ Branch pipe 12 ・ ・ ・ Pump 13
... Reaction tanks

Claims (1)

(57) [Claims] 1. An ozone-containing gas is generated in an anode chamber of an electrolytic cell by electrolyzing water, and a gas-liquid mixed state of the gas is provided with a fluororesin filter having a large number of fine diffused holes formed therein. A method for diffusing an ozone-containing gas, comprising supplying the mixture to a mixing tank, diffusing the ozone-containing gas through a filter into the mixing tank, and dissolving the ozone-containing gas in water in the mixing tank .