JP3734207B2 - Ozone water production method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention provides a method for producing ozone water used in, for example, semiconductor and liquid crystal production processes.To the lawIt is related.
[0002]
[Prior art]
  Conventionally, for example, ozone water used for removing organic substances in a semiconductor or liquid crystal manufacturing process is obtained by ultrapure water (in this specification, it is not always clearly defined that ozone gas generated by electrolysis of water or silent discharge is used. High-purity water explained in terms of unpurified water, ultrapure water, and the like are collectively referred to as “ultra-pure water”) and manufactured and supplied. That is, conventional ozone water is an ultrapure water production apparatus 11 composed of a pretreatment system 1, a primary pure water system 2, and a subsystem 3 as shown in FIG. It is manufactured by dissolving ozone in ultrapure water manufactured by treating raw water with an ozone dissolving section 4 (ozone dissolving means).
[0003]
  In FIG. 6, the pretreatment system 1 including the coagulating sedimentation apparatus 201, the filter 202, the filtrate water tank 203, and the like removes suspended substances and colloidal substances in the raw water. In the primary pure water system 2 including the ion exchanger 204, the ultraviolet sterilizer 205, the microfiltration membrane device 206, the reverse osmosis membrane device 207, etc., ions and organic components in the raw water are removed. The ion exchanger 204 removes the TOC component adsorbed or ion-exchanged by the ion exchange resin in addition to the salt removal. The reverse osmosis membrane device 207 removes ionic and colloidal TOC in addition to salt removal.
[0004]
  In the subsystem 3 including the deaerator 209, the ultraviolet oxidizer 210, the polisher (non-regenerative ion exchanger) 211, and the ultrafiltration membrane device 212, the purity of the treated water obtained from the primary pure water system 2 is further increased. Use pure water. In the ultraviolet oxidizer 210, the TOC component is converted into an organic acid or CO 2 by 185 nm ultraviolet rays emitted from a low-pressure ultraviolet lamp.₂Disassemble until Decomposed organic matter and CO₂Is removed by a subsequent ion exchange resin. In the ultrafiltration membrane device 212, the fine particles are removed and the outflow particles of the ion exchange resin are also removed. The obtained ultrapure water is supplied to each use point, and the remainder is returned to the primary pure water tank 208 and supplied to the subsystem 3. On the other hand, ozone water obtained by the ozone generator 214 is dissolved in ultrapure water branched downstream of the ultrafiltration membrane device 212 by the ozone dissolver 213, for example, 2 to 10 mg / L to produce ozone water. The ozone water produced in this way is appropriately supplied to each use point and used for cleaning and removing organic substances adhering to the wafer surface.
[0005]
[Problems to be solved by the invention]
  However, ozone is an unstable substance and self-decomposes in water and is converted to oxygen. When ozone water is produced by dissolving ozone in the ultrapure water produced by the above-described conventional treatment method, the half-life at which the dissolved ozone concentration becomes half immediately after dissolution is about 1 minute due to the self-decomposition of ozone. . For this reason, the conventional ozone water production method has the following problems.
[0006]
(1) Even if the piping design is such that the ozone water transfer time is less than 1 minute, the ozone concentration immediately after dissolution must be more than double the concentration required at the point of use. A large excess of ozone must be produced.
(2) Ozone has significantly higher solubility in water than oxygen. Self-decomposed ozone becomes oxygen, but if the ozone concentration required at the point of use is high, oxygen is oversaturated by the self-decomposition of ozone during piping transfer, foaming at the point of use, and stable nozzle injection, etc. Hinder.
(3) When supplying ozone water to multiple use points, etc., the amount of ozone water used varies depending on the usage status at each use point, and the time for ozone water to reach each use point is not constant. For this reason, the decrease in ozone concentration is not constant, and the ozone concentration at the use point becomes unstable.
(4) Due to strict restrictions on the transfer time, ozone water production equipment is usually installed in the immediate vicinity of each use point, but when the use points are distributed over a wide area in the factory, It is necessary to install and operate an ozone water production device, which requires a larger installation area as compared to the case where ozone water is produced centrally with a single ozone water production device. Bulky.
[0007]
  Therefore, the object of the present invention is to slow down the self-decomposition rate of ozone water, and to produce and supply ozone water centrally with a single ozone water production device, even for multiple use points distributed over a wide area in the factory. In addition, there is no need to produce a large excess of ozone relative to the required amount, there is little foaming due to supersaturated oxygen at the point of use, and ozone water production method that can supply ozone water with a stable concentration at the point of useThe lawIt is to provide.
[0008]
[Means for Solving the Problems]
  Under such circumstances, the present inventor has intensively studied, and as a result, the ultraviolet sterilizer and the ultraviolet oxidizer used in the conventional ultrapure water production apparatus have about 20-100 μg / L of hydrogen peroxide in ultrapure water. It is found that this hydrogen peroxide significantly promotes ozonolysis, and that the life of ozone water is significantly extended by controlling the hydrogen peroxide in ultrapure water that dissolves ozone below a specific concentration, The present invention has been completed.
[0009]
  That is, the present invention relates to (1) an ozone water production method for producing ozone water to be used at a use point by dissolving ozone in ultrapure water obtained by further processing water obtained by a primary pure water system. The water obtained by the primary pure water systemThe amount of hydrogen peroxide produced exceeds 15 μg / l.UV oxidation means andRemoval of hydrogen peroxide generated by the ultraviolet oxidation meansHydrogen peroxide removal handIn stepsPassing through water to obtain ultrapure water having a hydrogen peroxide concentration of 10 μg / l or less, and then dissolving ozone in the ultrapure water to obtain ozone water having an ozone concentration half life of 4 minutes or more. (2) The hydrogen peroxide removal means is an adsorption or decomposition treatment with an adsorbent, or a decomposition treatment with a palladium-supported ion exchange resin or a metal ion type cation exchange resin, or these treatments and subsequent stages. The ozone water production method, which is a combination treatment with a filtration treatment for removing fine particles, (3) the ozone water production method, wherein the pH of ultrapure water in which the ozone is dissolved is made acidic. (4) The method for producing ozone water is characterized in that the method of acidifying the pH of ultrapure water for dissolving ozone is a method of dissolving carbon dioxide in ultrapure water. .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
  Of the present inventionreferenceThe ozone water production apparatus in the embodiment will be described with reference to FIG.referenceThe ultrapure water production apparatus 11a for producing ultrapure water used in the embodiment omits the ultraviolet irradiation treatment (the ultraviolet sterilizer 205 and the ultraviolet oxidizer 210) from the conventional ultrapure water production apparatus shown in FIG. Ultrapure water having a hydrogen peroxide concentration of 15 μg / L or less is produced. In the figure, the pretreatment system 1 includes a coagulation / precipitation apparatus 201, a filter 202, a filtrate water tank 203, and the like, and here, suspended substances and colloid substances in raw water are removed. The primary pure water system 2 includes an ion exchanger 204, a microfiltration membrane device 206, a reverse osmosis membrane device 207, a primary pure water tank 208, and the like, and here, ions and organic components in raw water are removed. In the ion exchange device, in addition to removing salts, the TOC component adsorbed or ion exchanged by the ion exchange resin is removed. The reverse osmosis membrane device 207 removes ionic and colloidal TOC in addition to salt removal.
[0011]
  The sub system 3 includes a deaerator 209, a polisher (non-regenerative ion exchanger) 211, an ultrafiltration membrane device 212, and the like. Here, the purity of treated water obtained from the primary pure water system 2 is further increased. Use pure water. In the ultrafiltration membrane device 212, the fine particles are removed and the outflow particles of the ion exchange resin are also removed. The obtained ultrapure water is supplied to each use point, and the remainder is returned to the primary pure water tank 208 and then supplied to the subsystem 3. In general, ultrapure water produced by an ultrapure water production apparatus is used for various purposes such as cleaning, rinsing, and chemical dissolution in a factory. Therefore, the bookreferenceIn the embodiment, ultrapure water other than for ozone dissolution is used for conventional applications, and only ultrapure water for ozone dissolution is taken out from the ultrapure water production system through a branched pipe. That is, an ozone dissolving section comprising an ozone generator 214 and an ozone dissolver 213 connected to the pipe 10 branched from the main ultra pure water flow pipe 9 through which ultra pure water obtained by the ultra pure water production apparatus 11a flows. 4 (ozone dissolving means) is incorporated. BookreferenceSince the ultrapure water production apparatus 11a in the form does not normally use the ultraviolet sterilizer (ultraviolet sterilization means) and the ultraviolet oxidizer (ultraviolet oxidation means) that are used, there is no generation of hydrogen peroxide and ultrapure water. The concentration of hydrogen peroxide in the ultrapure water obtained from the production apparatus 11a is very low, almost 0 μg / L. For this reason, the ozone water in which ozone is dissolved in the ultrapure water is suppressed from self-decomposition and its life is significantly extended.
[0012]
  The method for dissolving ozone gas in ultrapure water is not particularly limited, and is a film dissolving method in which ozone gas is injected and dissolved in ultrapure water through a gas permeable membrane, and ozone gas is bubbled and dissolved in ultrapure water. Examples thereof include a method of dissolving ozone gas in ultrapure water via an ejector, a method of supplying ozone gas upstream of a pump that supplies ultrapure water to a gas dissolution tank, and a method of dissolving by stirring in the pump. The gas permeable membrane used for dissolving the membrane is preferably a fluororesin-based hydrophobic porous membrane that can withstand the strong oxidizing power of ozone, but is not limited thereto. Moreover, as an ozone generator, the ozone generator by a silent discharge, an electrolysis method, etc. is mentioned.
[0013]
  By dissolving ozone in ultrapure water, for example, a cleaning solution having a positive oxidation-reduction potential suitable for removal of organic substances on the surface of a semiconductor wafer or the like can be obtained, but usually the dissolved ozone concentration is 0.05 mg / It is preferable to dissolve ozone gas so as to be L or more, particularly 1 to 10 mg / L.
[0014]
  Of the present inventionreferenceThe ozone water production apparatus in the embodiment will be described with reference to FIG. In FIG. 2, the same components as those in the ozone water production apparatus in FIG. 1 are denoted by the same reference numerals, description thereof is omitted, and only differences from FIG. 1 will be mainly described. That is, the difference from FIG. 1 is that an ultraviolet sterilizer 205 is provided between the ion exchanger 204 and the microfiltration membrane device 206 of the primary pure water system 2. In general, the ultraviolet irradiation treatment refers to a treatment for irradiating the water to be treated for the purpose of sterilizing the water to be treated and / or decomposing and removing organic matter. As the ultraviolet ray generation source, a mercury lamp is generally used, and among the emission wavelengths of mercury, ultraviolet rays having a wavelength of around 185 nm and a wavelength of around 254 nm are effective for organic matter decomposition and sterilization, respectively. In general, the ultraviolet irradiation treatment apparatus is mainly intended for sterilization, mainly for ultraviolet light having a wavelength of about 254 nm, and for ultraviolet light sterilizer in which the ultraviolet light having a wavelength of about 185 nm is almost blocked by an optical filter, and for the main purpose of decomposing and removing organic matter. There is an ultraviolet oxidizer that irradiates the ultraviolet rays in the vicinity and near the wavelength of 254 nm. Both the ultraviolet sterilizer and the ultraviolet oxidizer produce hydrogen peroxide in the ultrapure water production system, but the amount of hydrogen peroxide produced is larger in the ultraviolet oxidizer for decomposing organic matter. BookreferenceIn the ozone water production and supply apparatus in the embodiment, an ultraviolet oxidizer is not used, and an ultraviolet sterilizer is provided in the primary pure water system 2, and in this case, depending on the ultraviolet irradiation amount and the treated water flow rate, Specifically, the ultrapure water supplied to the ozone water dissolver 213 is, for example, one having a hydrogen peroxide concentration of about 10 μg / L to 15 μg / L. However, from the viewpoint that the concentration of hydrogen peroxide in the ultrapure water is constantly maintained at 15 μg / L or less, it is desirable to provide a hydrogen peroxide decomposer as described later in the subsequent stage of the ultraviolet sterilizer 205. As in the case of the second embodiment, if ultrapure water has been subjected to an ultraviolet irradiation treatment with an intensity such that the amount of hydrogen peroxide produced is 15 μg / L or less in the ultrapure water production process, ozone is added to this. The lifetime of the ozone water in which is dissolved is significantly increased.
[0015]
  BookreferenceThe ozone water production apparatus in the embodiment will be described with reference to FIG. In FIG. 3, the same components as those in the ozone water production apparatus in FIG. 1 are denoted by the same reference numerals and description thereof is omitted, and only differences from FIG. 1 will be mainly described. That is, the main difference from FIG. 1 is that the ultraviolet sterilizer 205 is placed between the ion exchanger 204 and the microfiltration membrane device 206 of the primary pure water system 2, and the deaerator 209 and ion exchanger 211 of the subsystem 3. In addition, an ultraviolet oxidizer 210 is provided between them, and an organic matter adsorber 301 (organic matter) is further provided in a pipe 10a branched from the ultrapure water flow pipe 9 between the deaerator 209 and the ultraviolet oxidizer 210 of the subsystem 3. Removing means), an ion exchanger 302, and an ultrafiltration membrane device 303 are provided in this order from the upstream side to the downstream side, and ultrapure water that is treated water of the ultrafiltration membrane device 303 is supplied to the ozone dissolver 213. It is in the point made into the structure to do. That is, the organic substance adsorber 301 is an alternative to the ultraviolet oxidizer 210 disposed in the main ultrapure water flow pipe 9, and is branched to the pipe 10a side before the ultraviolet oxidizer 210 by this organic substance adsorption treatment. Organic substances contained in ultrapure water that has not been subjected to ultraviolet oxidation treatment are removed. The adsorbent used in the organic substance adsorber 301 is not particularly limited as long as it can adsorb organic substances in water or an aqueous solution, and examples thereof include activated carbon and a synthetic adsorbent. Activated carbon is generally activated from wood, sawdust, coal, coconut shell, and the like, carbonized and activated. From its shape, it can be divided into granular charcoal having a particle diameter of about 0.4 to 1.7 mm and powdered charcoal having a particle diameter of less than that. Among these, granular coal is preferable for the purpose of the present invention. Synthetic adsorbents are generally organic polymers and are intended for non-ion exchange adsorption, and examples thereof include styrene-divinylbenzene copolymers and acrylic ester copolymers. Specific examples of the synthetic adsorbent include Amberlite XAD-2, XAD-4, XAD-2000, XAD-16, XAD-7, and XAD-8. Further, a carbonized synthetic adsorbent can also be used as the organic adsorbent, such as Ambersorb 252.
[0016]
  Moreover, when the organic substance adsorption process by the above adsorbents replaced with an ultraviolet oxidation process is performed, mixing of the fine particles into the treated water may be a problem. In this case, a particulate removing filter may be provided after the organic substance removing means. Examples of the fine particle removing filter include membrane treatment devices such as a microfiltration membrane device and an ultrafiltration membrane device. As the microfiltration membrane, an organic membrane having pores having a pore diameter of about 0.1 to 1 μm can be used. For the ultrafiltration membrane, a polysulfone membrane having a fractional molecular weight of about 3,000 to 10,000 or a cellulose acetate membrane can be used. As the module shape in the microfiltration membrane device and the ultrafiltration membrane device, a hollow fiber shape, a spiral shape, a tubular shape, a flat membrane shape, or the like can be used. In FIG. 3, the ultraviolet sterilizer 205 of the primary pure water treatment system 2 may be omitted. That is, by bypassing the ultraviolet sterilizer 205 and passing water, the concentration of hydrogen peroxide in the ultrapure water supplied to the ozone dissolver 213 can be further reduced. BookreferenceIf the ultraviolet oxidation means is not used in the ultrapure water production process as in the form, as an alternative, the ultrapure water that dissolves ozone by providing the organic substance removing means or the organic substance removing means and the fine particle removing means at the subsequent stage. The organic matter inside can be removed effectively.
[0017]
  The present inventionThe fruitThe ozone water production apparatus in the embodiment will be described with reference to FIG. In FIG. 4, the same components as those in the ozone water production apparatus in FIG. 3 are denoted by the same reference numerals, description thereof is omitted, and only differences from FIG. 3 will be mainly described. That is, the main difference from FIG. 3 is that in the pipe 10b branched from the ultrapure water circulation pipe 9 between the ultraviolet oxidizer 210 and the polisher 211 of the subsystem 3, the excess is directed from the upstream side toward the downstream side. A hydrogen oxide decomposer 401 (hydrogen peroxide removing means), an ion exchanger 402, a carbon dioxide dissolver 403, and an ultrafiltration membrane device 404 are provided in this order, and treated water of the ultrafiltration membrane device 404 is supplied to an ozone dissolver 213. It is the point which was set as the structure supplied to. That is,RealIn an ultrapure water production apparatus equipped with a conventional ultraviolet sterilizer and ultraviolet oxidizer, the embodiment removes hydrogen peroxide generated by these ultraviolet irradiation treatments by hydrogen peroxide removing means, The hydrogen peroxide concentration is 15 μg / L or less. In addition, carbon dioxide is dissolved in ultrapure water by the carbon dioxide dissolver 403 to make the ultrapure water acidic, thereby suppressing the self-decomposition of ozone and further extending the life of ozone water. is there. As a means for removing hydrogen peroxide, water containing hydrogen peroxide is brought into contact with an adsorbent such as activated carbon or a synthetic adsorbent to adsorb or decompose hydrogen peroxide, and water containing hydrogen peroxide is replaced with palladium or the like. Examples thereof include a method of bringing hydrogen peroxide into contact with a supported ion exchange resin or metal ion type cation exchange resin and decomposing hydrogen peroxide by their catalytic action. As an adsorbent such as activated carbon or synthetic adsorbent, the above-mentionedreferenceThe same adsorbent used in the form can be used. As the metal ion type cation exchange resin, for example, a metal ion such as iron ion, copper ion, nickel ion, chromium ion, cobalt ion or the like adsorbed on a strongly acidic cation exchange resin can be used. In addition, it may be mixed in the hydrogen peroxide removing means after the hydrogen peroxide removing means is subjected to filtration processing for removing fine particles such as a microfiltration membrane device and an ultrafiltration membrane device as described above. This is preferable because fine particles can be removed.
[0018]
  As described above, by setting the hydrogen peroxide in the ultrapure water for dissolving ozone to 15 μg / L or less, the self-decomposition of ozone can be suppressed and the life of the ozone water can be extended. If the pH of water is made acidic, the lifetime of ozone water can be further extended. The means for making the pH acidic is not particularly limited as long as the purpose of use of the ozone water is not hindered, but the method of dissolving carbon dioxide as described above is preferable because it has no persistence and is relatively low in cost. Examples of the method for dissolving carbon dioxide in ultrapure water include bubbling carbon dioxide in ultrapure water, mixing with a line mixer, and dissolving a membrane with a gas permeable membrane. Gas-permeable membranes used for membrane dissolution are non-porous membranes such as polydimethylsiloxane, polyolefin, and polysulfone; hydrophobic porous membranes such as fluororesin, polyethylene, and polypropylene are modularized into hollow fibers and spirals. Can be used.
[0019]
  RealAs in the embodiment, when ultrapure water has been subjected to ultraviolet irradiation treatment with an intensity of hydrogen peroxide exceeding 15 μg / L in the process of producing ultrapure water, excess water is added to the ultrapure water. If ozone is dissolved after the hydrogen oxide removal treatment, self-decomposition of the obtained ozone water is suppressed, and the life of the ozone water can be extended. Further, if the pH of ultrapure water that dissolves ozone water is made acidic, the ozone water has a longer life.
[0020]
  In the present invention, the ultrapure water in which ozone is dissolved is not limited to the ultrapure water produced by the ultrapure water production apparatus in the above embodiment, but the suspended substance removal treatment, the ionic substance removal treatment, and the sterilization Water that has been purified by a system appropriately combined with treatment, organic matter removal treatment, particulate removal treatment, deaeration treatment, and the like, and the water quality is preferably one having a resistivity of 10 MΩ · cm or more, Further, those of 17 MΩ · cm or more are preferable. The concentration of hydrogen peroxide in the ultrapure water is 15 μg / L or less, preferably 10 μg / L or less, more preferably 0 μg / L before ozone dissolution.
[0021]
  In the present invention, as a method for quantifying low-concentration hydrogen peroxide in ultrapure water, a known phenol phthaline method, for example, the method described in Japanese Patent Publication No. 56-54582 may be used. That is, 30 ml of a test solution containing hydrogen peroxide was accurately collected in a beaker and 4 × 10 4^-3Add 0.3 ml of M phenol phthalin alkaline solution and add 4 × 10^-FourAdd 0.3 ml of M copper sulfate solution, stir gently and let stand for a few minutes. The solution exhibiting a pink red color is transferred to a colorimetric cell having an optical path length of 50 mm, and the absorbance is measured by spectroscopic analysis at a wavelength of 540 nm. From the absorbance-hydrogen peroxide concentration calibration curve prepared in advance based on the measured absorbance. What is necessary is just to determine the density | concentration of hydrogen peroxide.
[0022]
【Example】
  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.
referenceExample 1
  When treated with the ozone water production equipment shown in Fig. 1 using industrial water as the raw material, the resistivity of the ultrapure water supplied to the ozone dissolver 213 is 18.0 MΩ · cm, and the hydrogen peroxide concentration in the ultrapure water Was 0 μg / L. Ozone was dissolved in this ultrapure water using an ozone dissolver 213 to produce ozone water having an ozone concentration of about 10 mg / L. This ozone water was sent to each use point, and the ozone concentration at each use point was measured. The ozone concentration was measured by the phenol phthaline method. The results are shown in FIG. In the figure, the pipe transfer time means the time to reach each use point, and is obtained from the ozone water flow rate and the pipe length to each use point.
[0023]
referenceExample 2 andreferenceExample 3
  As the ozone water production apparatus shown in FIG. 2, the concentration of hydrogen peroxide in the ultrapure water supplied to the ozone dissolver 213 is 10 μg / L (referenceExample 2) and 15 μg / L (referenceExcept for example 3)referencePerformed as in Example 1. The results are shown in FIG.
[0024]
Comparative Example 1
  The ozone water production apparatus shown in FIG. 6 is the ozone water production apparatus except that the hydrogen peroxide concentration in the ultrapure water supplied to the ozone dissolver 213 is 35 μg / L.referencePerformed as in Example 1. The results are shown in FIG.
[0025]
  As is clear from FIG. 5, when ozone is dissolved in conventional ultrapure water containing hydrogen peroxide of 35 μg / L and ozone water is supplied by piping (Comparative Example 1), the half-life of the ozone concentration is about 1 minute. It is. For example, when designing an ozone water production system with the ozone concentration immediately after ozone dissolution being twice the required concentration at the point of use, the half-life of the ozone concentration is 1 minute in the conventional method, so the pipe transfer time is 1 minute. Must be within. As is normally done, if the linear velocity during pipe transfer is 1.0 to 1.5 m / second, the transfer pipe length is limited to 60 to 90 m or less in the conventional method. Normally, the piping in the factory is not laid in a straight line from the source to the destination, and includes many bends. It is very difficult to produce and supply ozone water to multiple use points. Ozone water production equipment must be individually installed in the immediate vicinity of each use point, and the overall design area and maintenance are maintained. Increase management costs. In contrast, for example,referenceIn Example 2, the hydrogen peroxide concentration in the ultrapure water is 10 μg / L, and in this case, the half-life of the ozone concentration can be 4 minutes or more. Similarly to the above, when designing ozone water production and supply equipment by setting the ozone concentration immediately after ozone dissolution to twice the required concentration at the point of use, the pipe transfer time can be set to 4 minutes or less. When the linear velocity is 1.0 to 1.5 m / sec, the pipe length can be extended to 240 to 360 m. If a pipe length of 240 to 360 m is possible, in most factories, ozone can be centrally produced and supplied to a plurality of use points dispersed in the factory with a single ozone water production device. Since the installation area of the ozone water production apparatus can be reduced, the initial investment and management and maintenance costs can be saved.
[0026]
  In addition, when the length of the ozone water transfer pipe is fixed as in the case of remodeling an existing ozone water production apparatus to the apparatus of the present invention, the ozone water production apparatus of the present invention is less ozone than the conventional apparatus. Since the ozone concentration immediately after melting can be kept low, it is possible to reduce the size of the ozone generation unit, reduce initial investment, and save energy for ozone production. Further, since the decrease in ozone concentration due to self-decomposition is suppressed to a small level, there is almost no foaming at the use point due to oxygen supersaturation, and ozone water having a stable concentration at the use point can be supplied.
[0027]
  For example, if the ozone water required amount at the use point is 10 L / min, the required concentration is 5 mg / L, and the ozone water pipe transfer time is 60 seconds, the half-life of the ozone concentration is 60 seconds in the apparatus of Comparative Example 1. The ozone concentration immediately after dissolution must be 10 mg / L or more. In this case, even if the ozone dissolution efficiency is 90%, the ozone generation amount of the ozone generation section must be 111 mg / min or more. On the other hand, when the apparatus of the embodiment is applied to the above ozone water supply conditions, the ozone concentration immediately after dissolution should be 6 mg / L or more, and the required ozone generation amount is 66.7 mg / min or more. It is possible to reduce the size of the ozone generator, thereby reducing initial investment and saving energy for ozone production.
[0028]
  Furthermore, in the above example, in the apparatus of Comparative Example 1, the ozone concentration decrease due to autolysis, that is, the oxygen increase reaches 5 mg / L. On the contrary,referenceIn the example apparatus, the decrease in ozone concentration can be suppressed to only 1 mg / L, and the foaming at the point of use due to oxygen supersaturation can be almost eliminated. In addition, when supplying ozone water to multiple use points, the amount of ozone water used varies depending on the use conditions at each use point, and the time to reach the ozone water at each use point is not constant. Although the concentration may become unstable, in the apparatus of the embodiment, the ozone concentration decrease amount is small, so that even in such a case, it is possible to supply ozone water having a stable ozone concentration.
[0029]
referenceExample 4
  Industrial water was used as raw water and treated using the ozone water production apparatus shown in FIG. 3 (however, the ultraviolet sterilizer 205 was not bypassed). A synthetic adsorbent (trade name “Ambersorb 252” manufactured by Rohm and Haas) was used for the organic substance adsorber 301. In FIG. 3, the resistivity of ultrapure water before ozone dissolution, the hydrogen peroxide concentration in the ultrapure water, the TOC (total organic carbon) component, and the fine particles were measured. As a result, the resistivity was 18.0 MΩcm, the hydrogen peroxide concentration was 1 μg / L, the TOC amount was 1 μg / L, and the fine particles of 0.1 μm or more were 1 particle / ml.referenceAccording to Example 4, since the organic substance adsorber is used instead of the ultraviolet oxidizer, the organic substance in the for-treatment water can be effectively removed. Moreover, the removal effect of hydrogen peroxide was also recognized.
[0030]
Example1
  It processed using the ozone water manufacturing apparatus shown in FIG. 4 by making industrial water into raw | natural water. For the hydrogen peroxide decomposer 401, an iron ion type strongly acidic cation exchange resin was used. In this ozone water production apparatus, the hydrogen peroxide which was 35 μg / L after the UV oxidizer 210 was reduced to 0 μg / L by the iron ion type cation exchange resin. The pH after the carbon dioxide dissolver 403 was 4.7. The attenuation of the concentration of ozone water produced by this ozone water production apparatus is shown in FIG. Example1According to the present invention, even if ultraviolet irradiation treatment is performed, if hydrogen peroxide removing means is provided at the subsequent stage, the concentration of hydrogen peroxide in ultrapure water that dissolves ozone is reduced.10It can be less than μg / L. Further, by making the pH of the ultrapure water acidic, it is possible to further extend the life of ozone water.
[0031]
【The invention's effect】
  According to the ozone water production method and apparatus of the present invention, ultrapure water produced by a treatment method that does not produce hydrogen peroxide, or ultrapure water from which hydrogen peroxide produced during the production of ultrapure water has been removed by subsequent treatment. Dissolve ozone, or dissolve ozone in ultrapure water that does not contain hydrogen peroxide and have an acidic pH, thereby slowing the self-decomposition rate of ozone in ozone water and dispersing it over a wide area in the factory Even for a plurality of use points, it is possible to centrally manufacture and supply ozone water with one ozone water production apparatus, and it is not necessary to produce a large excess of ozone with respect to the required amount, thereby reducing the cost. In addition, it is possible to supply ozone water that has little foaming due to supersaturated oxygen at the use point and has a stable concentration at the use point.
[Brief description of the drawings]
FIG. 1 of the present inventionreferenceIt is a block diagram of the ozone water manufacturing apparatus in a form.
FIG. 2 of the present inventionreferenceIt is a block diagram of the ozone water manufacturing apparatus in a form.
FIG. 3 of the present inventionreferenceIt is a block diagram of the ozone water manufacturing apparatus in an embodiment.
FIG. 4 The present inventionThe fruitIt is a block diagram of the ozone water manufacturing apparatus in an embodiment.
FIG. 5 is a diagram showing a relationship between ozone water pipe transfer time and ozone concentration attenuation;
FIG. 6 is a block diagram of a conventional ozone water production apparatus.
[Explanation of symbols]
  1 Pretreatment system
  2 Primary pure water system
  3 Subsystem
  4 Ozone dissolution part (ozone dissolution means)
  11, 11a-11d Ultrapure water production equipment
  201 Coagulation sedimentation equipment
  202 Filter
  203 Filtration water tank
  204 Ion exchanger
  205 UV sterilizer (UV sterilization means)
  206 Microfiltration membrane device
  207 Reverse osmosis membrane device
  208 Primary pure water tank
  209 Deaerator
  210 UV oxidizer (UV oxidizer)
  211, 302, 402 Ion exchanger
  212, 303, 404 Ultrafiltration membrane device
  213 Ozone dissolver
  214 Ozone generator
  301 Organic substance adsorber (Organic substance removal means)
  401 Hydrogen peroxide decomposer (hydrogen peroxide removing means)
  403 Carbon dioxide dissolver

Claims (4)

In an ozone water production method for producing ozone water to be used at a use point by dissolving ozone in ultrapure water obtained by further processing water obtained in a primary pure water system, the ozone water production method obtained in the primary pure water system water, hydrogen peroxide concentration in Rohm hydrogen peroxide removal means to remove the formed hydrogen peroxide by UV oxidation means and said ultraviolet oxidation unit intensity produced amount of hydrogen peroxide is more than 15 [mu] g / l A method for producing ozone water, comprising obtaining ultrapure water of 10 μg / l or less and then dissolving ozone in the ultrapure water to obtain ozone water having a half-life of ozone concentration of 4 minutes or more.   The hydrogen peroxide removing means is an adsorption or decomposition treatment with an adsorbent, a decomposition treatment with a palladium-supported ion exchange resin or a metal ion type cation exchange resin, or a combination treatment of these treatments and subsequent filtration treatment for removing fine particles. The method for producing ozone water according to claim 1, wherein:   The method for producing ozone water according to claim 1 or 2, wherein the pH of the ultrapure water in which the ozone is dissolved is made acidic.   The method for producing ozone water according to claim 3, wherein the method of acidifying the pH of the ultrapure water in which the ozone is dissolved is a method of dissolving carbon dioxide in the ultrapure water.

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