Method for producing functional water

Abstract

The present invention addresses the problem of providing a method for producing functional water having various properties using ozone microbubbles. A method for producing functional water according to the present invention as a means for solving the problem includes: a step A in which ozone microbubbles are caused in water containing a solid iron source and having a pH of 4.0 or less; and a step B in which the pH of the water after the step A is increased to 7.0 or more. The functional water thus produced has a shoulder-type absorption peak in a wavelength region near 270 nm and a wavelength region near 370 nm in a difference spectrum between a spectrum when measured at a pH of 7.0 and a spectrum when measured at a pH of 2.5 by lowering the pH of the functional water, the spectrums being obtained by an ultraviolet-visible near-infrared spectrophotometer.

Description

Functional water production method

[0001] The present invention relates to a method for producing functional water.

[0002] It is well known not only to those skilled in the art but also to the general public that a wide variety of functional waters that have been given useful properties through artificial processing have been proposed and put to practical use. Takahashi, the present inventor, has continued to research functional waters that utilize microbubbles and nanobubbles, which are tiny bubbles, for many years, and has achieved many results. One of these results is reported in Patent Document 1 that functional water (ozone water) can be produced by dissolving an organic iron compound and an inorganic salt in water in which ozone microbubbles have been generated.

[0003] The functional water reported by Takahashi in Patent Document 1 has been highly praised as ozone water with excellent storage stability and exhibiting oxidizing, sterilizing, and deodorizing effects. Subsequent research has suggested that functional water using ozone microbubbles has the potential to be endowed with a variety of additional properties.

[0004] Patent No. 6341581

[0005] Therefore, an object of the present invention is to provide a method for producing functional water having various properties by using ozone microbubbles.

[0006] The present inventors have conducted extensive research in light of the above points and have found that by using a solid iron source and ozone microbubbles to control the pH of water, it is possible to produce functional water that has properties such as an oxidizing effect, a bactericidal effect, a deodorizing effect, an effect of stably coexisting permanganate ions, an effect of activating organisms (including an effect of improving the dysfunction of organisms), and an effect of imparting hydrophilicity.

[0007] The method for producing functional water of the present invention, based on the above findings, comprises, as claimed in claim 1, step A of introducing ozone microbubbles into water containing a solid iron source and having a pH of 4.0 or less, and step B of increasing the pH of the water to 7.0 or higher after step A. A method for producing functional water according to claim 2 further comprises dissolving a divalent manganese compound during step A. A method for producing functional water according to claim 3 further comprises the method for producing functional water according to claim 1, wherein the functional water has hump-shaped absorption peaks in the wavelength ranges around 270 nm and 370 nm in the difference spectrum obtained by a UV-Vis-NIR spectrophotometer between the spectrum measured at pH 7.0 and the spectrum measured at pH 2.5 by lowering the pH of the functional water. Furthermore, as described in claim 4, the functional water of the present invention has a pH of 6.0 or higher, and in the difference spectrum obtained by an ultraviolet-visible-near-infrared spectrophotometer between the spectrum measured at pH 7.0 and the spectrum measured at pH 2.5 by lowering the pH of the functional water, the difference spectrum has hump-shaped absorption peaks in the wavelength ranges around 270 nm and 370 nm. Furthermore, as described in claim 5, the present invention relates to the use of the functional water of claim 4 as an oxidizing agent. Furthermore, as described in claim 6, the present invention relates to the use of the functional water of claim 4 as a disinfectant. Furthermore, as described in claim 7, the present invention relates to the use of the functional water of claim 4 as a deodorizer. Furthermore, as described in claim 8, the present invention relates to the use of the functional water of claim 4 as a bioactivator. Furthermore, as described in claim 9, the present invention relates to the use of the functional water of claim 4 as a hydrophilicity-imparting agent.

[0008] According to the present invention, a method for producing functional water having various properties using ozone microbubbles can be provided.

[0009] 1 shows a measured spectrum of the functional water of the present invention (pH 7.0) produced in Example 1, a measured spectrum after adding hydrochloric acid to adjust the pH to 2.5, and a difference spectrum between the two, all obtained by an ultraviolet-visible-near-infrared spectrophotometer. 1 shows a measured spectrum of the functional water of Patent Document 1 produced in Comparative Example 1 after adding hydrochloric acid to adjust the pH to 7.0, and a measured spectrum after further adding hydrochloric acid to adjust the pH to 2.5. 1 shows a measured spectrum of the functional water of the present invention (pH 7.0) produced in Example 3, a measured spectrum after adding hydrochloric acid to adjust the pH to 2.5, and a difference spectrum between the two.

[0010] The method for producing functional water of the present invention comprises step A of introducing ozone microbubbles into water containing a solid iron source and having a pH of 4.0 or less, and step B of increasing the pH of the water after step A to 7.0 or more. The method for producing functional water of the present invention will be described below in order.

[0011] First, step A is performed in which ozone microbubbles are introduced into water containing a solid iron source and having a pH of 4.0 or less. The water containing the solid iron source and having a pH of 4.0 or less is water whose pH has been adjusted to 4.0 or less by dissolving an inorganic acid (such as hydrochloric acid, sulfuric acid, or nitric acid). The pH of the water is preferably 3.5 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. There are no particular limitations on the type of water, and ultrapure water, pure water, distilled water, tap water, seawater, etc. can be used. The electrical conductivity of the water is preferably 100 mS / cm or less, more preferably 50 mS / cm. The solid iron source to be added to the water having a pH of 4.0 or less is a solid in the form of iron wire, rebar, iron balls, iron granules, iron sand, etc., and is not limited to a solid made of iron alone. It may also be a solid made of an alloy (steel or stainless steel) containing iron as the main component (e.g., 50% or more), such as carbon steel containing only carbon added to iron, or special steel containing nickel, chromium, etc. The amount of the solid iron source to be added to the water having a pH of 4.0 or less is desirably an amount (e.g., 15 mg or more per 1 L of water) that will not cause the solid iron source to be completely dissolved and lost during step A. If the solid iron source added to the water is lost during step A, the functional water of the present invention may not be produced sufficiently.

[0012] The system for carrying out step A may or may not be metal-free, but when step A is carried out in a metal-free system, the container for carrying out step A is made of glass or synthetic resin, and the devices and instruments to be placed in water have at least an outer surface made of synthetic resin, or if the outer surface is made of metal, are coated with synthetic resin. When step A is carried out in a metal-free system, the lower limit of the pH of the water into which the solid iron source is added is desirably 2.0. If the pH of the water into which the solid iron source is added is below 2.0, there is a risk that the synthetic resin used to make the system metal-free will dissolve into the system and become contaminated.

[0013] A simple method for introducing ozone microbubbles into water containing a solid iron source and having a pH of 4.0 or less is to place an ozone microbubble generator in water and generate ozone microbubbles immediately (at the latest within 60 minutes) after adding the solid iron source to the water having a pH of 4.0 or less. If the time is allowed to pass, rusting of the solid iron source may progress, potentially resulting in insufficient production of the functional water of the present invention. The ozone microbubbles to be generated preferably have a particle size of 1 to 100 μm. For example, when the amount of water is 1 to 1,000 L, the time for generating ozone microbubbles is preferably 3 minutes or more, and more preferably 5 minutes or more. If the time for generating ozone microbubbles is too short, the functional water of the present invention may not be sufficiently produced. There is no particular upper limit to the time for generating ozone microbubbles, but considering production efficiency, it is preferably 5 hours, for example.

[0014] The ozone microbubble generator may be a microbubble generator using a known two-phase flow swirl method or a pressure dissolution method. When using the two-phase flow swirl method, a vortex with a radius of 10 cm or less is forcibly generated using a rotor or the like, and the ozone-containing gas-liquid mixture is struck against an obstacle such as a wall or a fluid with a different relative velocity. The ozone-containing gas components captured in the vortex are dispersed as the vortex disappears, thereby generating a large amount of desired ozone-containing microbubbles. When using the pressure dissolution method, ozone-containing gas is dissolved in water under high pressure of 2 atmospheres or more, and then the resulting solution is released to atmospheric pressure, resulting in supersaturation of the dissolved ozone-containing gas, generating ozone-containing bubbles. In this case, a large number of vortices with a radius of 1 mm or less are generated at the pressure release site using the water flow and obstacles, and a large number of gas phase nuclei (bubble nuclei) are formed due to the molecular vibration of water in the central region of the vortex flow. Furthermore, under supersaturated conditions, gas components containing ozone in the water are diffused toward these bubble nuclei, causing the bubble nuclei to grow, thereby generating a large amount of desired ozone-containing microbubbles. The microbubbles thus generated have a particle size of 50 μm or less, and their total number is approximately 1,500 to 10,000 per mL (see, for example, Japanese Patent Application Laid-Open Nos. 2000-51107 and 2003-265938). The ozone gas used to generate ozone microbubbles is, for example, 1 to 300 g / Nm3 using a commercially available oxygen-source ozone generator. ３ The concentration may be adjusted to 1 g / Nm ３ If ozone gas with a concentration of less than 300 g / Nm is used, it may not be possible to efficiently generate a large amount of ozone microbubbles in water. ３ It is difficult to prepare an ozone gas exceeding this concentration. The ozone gas may contain oxygen, nitrogen, etc. in addition to ozone.

[0015] The method for causing ozone microbubbles to exist in water containing a solid iron source and having a pH of 4.0 or less is not limited to the method using an ozone microbubble generator, and may be, for example, a method in which ozone is bubbled into water containing a solid iron source and having a pH of 4.0 or less, and the ozone is then incorporated into microbubbles contained in gas bubbles that are generated when the solid iron source dissolves.

[0016] Next, step B is carried out to raise the pH of the water after step A to 7.0 or higher, thereby producing the functional water of the present invention. Step B may be carried out using an alkali such as sodium hydroxide or calcium carbonate, and is preferably carried out within a short period of time (at most 10 minutes) after step A (at most within 3 hours, preferably within 30 minutes). A long delay or prolonged period of time may result in insufficient production of the functional water of the present invention. While there is no particular upper limit to the pH, setting the upper limit to 10.0, preferably 9.0, allows the produced functional water of the present invention to be used as is as a versatile functional water without pH adjustment. However, since the functional water of the present invention produced in this manner is stable at both alkaline and acidic pHs, the pH may be adjusted after production (although it is preferable to adjust the pH at least 10 seconds after step B). Depending on the intended use of the functional water of the present invention, if necessary, the produced functional water of the present invention may be allowed to stand for a predetermined time (e.g., 1 hour to 1 week) after step B, and then filtered to remove any precipitates such as particulate matter or flocs (the filtration process may be omitted by using the supernatant as the functional water of the present invention).

[0017] The functional water of the present invention thus produced has properties such as oxidizing, bactericidal, and deodorizing effects, as well as the effect of stably coexisting permanganate ions, the effect of activating organisms (including the effect of improving biological dysfunction), and the effect of imparting hydrophilicity. In the difference spectrum obtained by a UV-Vis-NIR spectrophotometer between the spectrum measured at pH 7.0 and the spectrum measured at pH 2.5 by lowering the pH of the functional water, the functional water has hump-shaped absorption peaks in the wavelength ranges of around 270 nm and around 370 nm in the near-ultraviolet region (here, "around" means within a range of ±30 nm). No functional water produced using ozone microbubbles known to date has such a unique absorption waveform.

[0018] The effect of allowing permanganate ions to coexist stably in the functional water of the present invention can be achieved by dissolving a divalent manganese compound such as manganese nitrate, manganese sulfate, or manganese chloride during step A for producing the functional water of the present invention. The divalent manganese compound may be a hydrate, and by dissolving it during step A to a concentration of, for example, 0.1 μM to 10 mM, the divalent manganese ions are converted to heptavalent permanganate ions, and the converted heptavalent permanganate ions are maintained stably for a long period of time (50% or more is maintained even six months after the production of the functional water of the present invention). The divalent manganese ions are converted to trivalent manganese oxide (Mn ２ O ３ ) and tetravalent manganese oxide (manganese dioxide: MnO ２ ) is produced and precipitated, but only in small amounts (if produced, it can be removed by filtration as necessary, as described above).

[0019] When the target of treatment is soil, the oxidizing, bactericidal, and deodorizing effects of the functional water of the present invention can be exerted by spraying the functional water of the present invention on the target of treatment. When the target of treatment is various daily necessities or other items, the effects can be exerted by spraying or applying the functional water of the present invention to the target of treatment, or by immersing the target of treatment in the functional water of the present invention. When the target of treatment is wastewater containing organic matter, the effects can be exerted by adding the functional water of the present invention to the target of treatment. When the target of treatment is an indoor space, the effects can be exerted by spraying the functional water of the present invention on the target of treatment. The biological activation effect of the functional water of the present invention (including the effect of improving biological dysfunction) can be exerted by having animals drink the functional water of the present invention, by providing the functional water of the present invention as water to plants (including seeds, bulbs, cut flowers, and cut branches), and by adding the functional water of the present invention to culture solutions or media for animal and plant cells and microorganisms. The hydrophilicity-imparting effect of the functional water of the present invention can be exerted by spraying or applying the functional water of the present invention to a treatment object (such as a windowpane for a building or vehicle, a biological material such as an artificial joint, an indwelling device such as a stent, or an article such as a contact lens) or by immersing the treatment object in the functional water of the present invention. Interestingly, the hydrophilicity-imparting effect of the functional water of the present invention is exerted not only when the surface of the treatment object is wet due to the presence of the functional water of the present invention, but also when the functional water of the present invention is no longer present on the surface of the treatment object due to subsequent drying.

[0020] The method for producing the functional water of the present invention as described above does not preclude dissolving organic iron compounds such as ammonium iron citrate or iron fulvate, or inorganic salts such as sodium chloride or magnesium sulfate, dissolved in water in which ozone microbubbles have been generated to produce the functional water reported by Takahashi in Patent Document 1, in water containing a solid iron source and having a pH of 4.0 or less. However, when dissolving these compounds, it is desirable to dissolve them so that the electrical conductivity of the water does not exceed 100 mS / cm.

[0021] The present invention will be described in detail below with reference to examples, but the present invention should not be construed as being limited to the following description.

[0022] Example 1: Production of functional water of the present invention in a metal-free system (Part 1) (Step A) 10 L of ultrapure water with an electrical conductivity of 0.06 μS / cm was placed in a 15 L glass vessel, and hydrochloric acid was added to adjust the pH of the water to 3.5. Then, 1 m (approximately 250 mg) of commercially available steel wire with a diameter of 0.5 mm (iron content: approximately 99.5%) was folded in four and placed in the vessel as a solid iron source. When the Fe2p spectrum of the steel wire used was measured using an X-ray photoelectron spectroscopy (XPS), a peak was observed at approximately 707 eV, which is the peak position of zero-valent iron (the wire can supply iron ions by dissolving in water with a pH of 3.5). Next, an all-Teflon (registered trademark) pressure dissolution type microbubble generator (Dan-Takuma A-01) was placed in water and started operating immediately after the steel wire was inserted, generating ozone microbubbles with a particle size of 15 to 50 μm at a rate of approximately 6,000 bubbles / mL. A commercially available oxygen source ozone generator was used as the microbubble generator, generating approximately 50 g / Nm. ３ The ozone gas prepared at a concentration of 100 ppm was supplied at a rate of about 1 L / min.

[0023] (Step B) The operation of the microbubble generator was stopped 10 minutes after it was started, and immediately after that, sodium hydroxide dissolved in distilled water was added while stirring the water with a stainless steel spoon. The pH of the water was raised to 7.0 in about 3 minutes, and the water was left to stand overnight in an indoor environment. The water was then filtered through a 0.45 μm membrane filter (no noticeable precipitate was observed on the filter), and the functional water of the present invention was obtained as a filtrate.

[0024] The functional water of the present invention thus produced was measured using an ultraviolet-visible-near-infrared spectrophotometer (JASCO V-750; the same applies hereinafter), and also after adding hydrochloric acid to lower the pH of the water to 2.5. The difference spectrum obtained from the former and latter measured spectra showed bump-shaped absorption peaks in the wavelength ranges of approximately 270 nm and 370 nm (the respective absorbance height components were approximately 0.001 and 0.003). The measured spectrum (of the functional water of the present invention) before the addition of hydrochloric acid, the measured spectrum after the addition of hydrochloric acid, and the difference spectrum between the two are shown in Figure 1 (before + HCl, after + HCl, and difference, respectively; the vertical axis represents absorbance and the horizontal axis represents wavelength). The reason why the functional water of the present invention has such a unique absorption waveform is thought to be that the functional water of the present invention contains nanometer-sized bubbles (e.g., 1 to 50 nm in diameter) covered with a thin solid shell that is likely to be mainly composed of iron oxide, and that light is absorbed and scattered by localized surface plasmon resonance originating from these bubbles.

[0025] Example 2: Production of functional water of the present invention in a non-metal-free system The functional water of the present invention was obtained in the same manner as in Example 1, except that a steel wire was placed in distilled water whose pH had been adjusted to 2.0, and a two-phase swirling flow microbubble generator (Aqua-Air, made of stainless steel) capable of generating microbubbles mainly with a particle size of 5 to 50 μm was used. The functional water of the present invention thus produced was measured with a UV-visible-near-infrared spectrophotometer in the same manner as in Example 1, and also measured after adding hydrochloric acid to lower the pH of the water to 2.5. The difference spectrum between the former and latter measured spectra was obtained, and it was found to have nodular absorption peaks in the wavelength ranges around 270 nm and 370 nm.

[0026] Comparative Example 1: Production of functional water (ozone water) according to Patent Document 1 in a non-metal-free system Ozone water was produced according to Example 1 of Patent Document 1. Specifically, ozone microbubbles were generated in distilled water using the SUS microbubble generator used in Example 2. A commercially available oxygen-source ozone generator was used as the microbubble generator, generating ozone microbubbles at a rate of approximately 30 g / Nm. ３Ozone gas prepared at a concentration of 0.01% was supplied at a rate of approximately 100 mL / min. By continuing to generate ozone microbubbles, it was confirmed that the redox potential of the water continuously increased from the initial value of approximately +500 mV. After 30 minutes had elapsed since the redox potential reached +600 mV, 10 μM of ammonium iron citrate as an organic iron compound and 50 mM of sodium chloride as an inorganic salt were dissolved, and the pH was adjusted to 8.0 using sodium hydroxide. Ozone microbubbles were then generated for another hour to produce ozone water. The ozone water thus produced was added with hydrochloric acid to lower the pH to 7.0, and then measured using a UV-visible-near-infrared spectrophotometer in the same manner as in Example 1. Furthermore, hydrochloric acid was added to lower the pH of the water to 2.5, and a measurement was also performed. The difference spectrum between the former and latter measured spectra was obtained, and no hump-shaped absorption peaks were observed in the wavelength ranges around 270 nm and 370 nm (the difference spectra are shown in FIG. 2).

[0027] Example 3: Production of functional water of the present invention in a metal-free system (Part 2) Step A was carried out in the same manner as step A in Example 1, except that 0.3 g of manganese (II) sulfate pentahydrate (amount to give a concentration of about 0.1 mM) was dissolved while generating ozone nanobubbles by operating a microbubble generator for 10 minutes in step A of Example 1. The water gradually turned light purple (pink), suggesting the generation of permanganate ions in the water. Next, step B was carried out in the same manner as step B in Example 1 (no change in water color), and the mixture was left to stand overnight in an indoor environment, after which it was filtered through a 0.45 μm membrane filter (a brown precipitate was observed on the filter), and the functional water of the present invention was obtained as a filtrate. The functional water of the present invention thus produced was measured using a UV-visible-near-infrared spectrophotometer, as in Example 1, and also after adding hydrochloric acid to lower the pH of the water to 2.5. The difference spectrum between the former and latter spectra revealed hump-shaped absorption peaks in the wavelength ranges of approximately 270 nm and 370 nm (the absorbance height components were approximately 0.004 and 0.006, respectively). The spectra measured before and after the addition of hydrochloric acid (the functional water of the present invention) and the difference spectrum between them are shown in Figure 3 (before + HCl, after + HCl, and difference, respectively; the vertical axis represents absorbance and the horizontal axis represents wavelength). The absorption peaks between 480 and 600 nm in the spectra measured before and after the addition of hydrochloric acid are attributable to permanganate ions (their presence remains unchanged before and after the addition of hydrochloric acid, so no absorption peaks appear in the difference spectrum).

[0028] Example 4: Effect of Stably Coexisting Permanganate Ions in the Functional Water of the Present Invention The functional water of the present invention produced in Example 3 was filled into a PET bottle and stored at room temperature for 6 months. After that, it was measured using a UV-Vis-NIR spectrophotometer in the same manner as in Example 1. It was also measured after adding hydrochloric acid to lower the pH of the water to 2.5. The difference spectrum between the former and latter spectra showed nodular absorption peaks in the wavelength ranges of around 270 nm and 370 nm. Approximately 70% of the permanganate ion concentration immediately after production remained.

[0029] Example 5: Stability of functional water of the present invention The pH of the functional water of the present invention produced in Example 1 was adjusted to 5.0 using hydrochloric acid, then to 9.0 using sodium hydroxide, and then again to 7.0 using hydrochloric acid. As in Example 1, the pH was measured using an ultraviolet-visible-near-infrared spectrophotometer, and further measured after adjusting the pH to 2.5 using hydrochloric acid. The difference spectrum between the former and latter measured spectra was obtained, and it showed hump-shaped absorption peaks in the wavelength ranges around 270 nm and 370 nm.

[0030] Example 6: Production of functional water of the present invention in a metal-free system (Part 3) Except for using a water mixture (electrical conductivity: approximately 8 mS / cm) prepared by mixing tap water from the Sendai City Waterworks Bureau in Miyagi Prefecture and seawater collected from Sendai Bay in a volume ratio of 5:1, functional water of the present invention was obtained in the same manner as in Example 3. The functional water of the present invention thus produced was measured with a UV-visible-near-infrared spectrophotometer in the same manner as in Example 1, and also after adding hydrochloric acid to lower the pH of the water to 2.5. The difference spectrum between the former measured spectrum and the latter measured spectrum was obtained, and it was found to have hump-shaped absorption peaks in the wavelength ranges of around 270 nm and 370 nm.

[0031] Example 7: Oxidation effect of functional water of the present invention (hydroxyl radical generating effect) Ethylenediaminetetraacetic acid (EDTA) was added to the functional water of the present invention produced in Example 1 to a concentration of 50 mM, and the spin trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) was added to a concentration of 300 mM. Hydrochloric acid was then added to a concentration of 100 mM, and electron spin resonance (ESR) measurements were performed. The spectrum of the spin adduct DMPO-OH (a spectrum indicating the generation of hydroxyl radicals) was observed. Similar measurements were performed by further adding ethanol as a radical scavenger to a concentration of 4 M, and a decrease in the spectrum of DMPO-OH was observed.

[0032] Example 8: Effect of functional water of the present invention on activating living organisms (Part 1) Cut gerbera flowers were placed in water to which potassium chloride was added to the functional water of the present invention produced in Example 1 to make a 1 mM concentration, and the changes in freshness over time were observed indoors. There was almost no change even after three weeks, and the cut flowers maintained their freshness. A similar experiment was conducted using tap water to which potassium chloride was added to make a 1 mM concentration, and tap water to which three commercially available cut flower preservatives were added according to their instructions. All of the cut flowers had wilted after three weeks.

[0033] Example 9: Effect of functional water of the present invention on activating living organisms (part 2) A cat (10-year-old female Scottish Fold) with liver dysfunction that had been kept with free access to commercially available mineral water was kept with free access to commercially available mineral water to which 10% of the functional water of the present invention produced in Example 3 had been added. After one month, even though the cat had not been administered any drugs to improve liver function, the ALT (GPT) level, an indicator of liver dysfunction, decreased from over 1000 U / L to the normal value of 62 U / L, and the SAA level, an inflammatory marker, also decreased from 30.94 μg / mL to the normal value of 3.75 μg / mL or less, and remained at normal levels thereafter.

[0034] Example 10: Effect of functional water of the present invention on activating living organisms (part 3) A dog (a 12-year-old male toy poodle) with liver dysfunction was given about 1 mL of the functional water of the present invention produced in Example 3 with a dropper twice a day, morning and evening. After one month, the ALT (GPT) level, an indicator of liver dysfunction, decreased from 139 U / L to the normal value of 47 U / L, even though the dog was not administered any liver function improving drugs. The ALP level also decreased from 316 U / L to 91 U / L, approaching the normal value.

[0035] Example 11: Bactericidal and deodorizing effects of the functional water of the present invention In a building with a strong odor where food waste containing a large amount of vegetables was stored as a fuel source for biomass power generation, the functional water of the present invention produced in Example 3 was sprayed using a pressurized sprayer, and the odor index was measured and a bacteria falling test was conducted using a standard agar plate medium.The odor index was 23 before the start of spraying, but fell to 10 or less 10 minutes after the start.The number of bacteria falling was 100 or more before the start of spraying, but fell to 10 or less 10 minutes after the start of spraying.

[0036] Example 12: Effect of the Functional Water of the Present Invention on Imparting Hydrophilicity In a clean air environment, the functional water of the present invention produced in Example 1 was sprayed onto an architectural window glass that had been cleaned with a commercially available glass cleaner. The surface became uniformly and evenly wet, forming a thin water film. The window glass was then allowed to air dry, and after the functional water of the present invention was no longer present on the surface, tap water was poured over it. The surface became uniformly and evenly wet again, forming a thin water film. The window glass was then left outdoors and observed. It was found that the surface remained uniformly and evenly wet with a thin water film during rainy weather for more than three months after the start of observation. During this period, the degree of soiling on the window glass surface was minimal and inconspicuous. These results are presumed to be due to the improved wettability of the window glass surface resulting from the hydrophilicity-imparting effect of the functional water of the present invention. The reason for the improved wettability of the window glass surface is believed to be due to the electrostatic adsorption of nanometer-sized bubbles present in the functional water of the present invention, covered with a thin solid shell likely composed primarily of iron oxide (the bubbles are believed to be the source of light absorption and scattering due to localized surface plasmon resonance, as mentioned in Example 1), to the window glass surface. The reason for the maintenance of improved wettability even after the functional water of the present invention is no longer present on the window glass surface is believed to be due to the bubbles continuing to adsorb to the surface even after the functional water of the present invention is no longer present. This consideration is supported by a separate experiment conducted in a clean air environment in which the functional water of the present invention produced in Example 1 was dropped onto poly-L-lysine (PLL)-coated mica substrates and 3-aminopropyltriethoxysilane (APTES)-coated mica substrates, and the substrates were left for 10 minutes, then rinsed with ultrapure water. The surfaces of the substrates were then analyzed with an atomic force microscope (AFM), confirming the stable adhesion of spherical microparticles with diameters of approximately 5 to 30 nm, completely covering the substrate surface.

[0037] INDUSTRIAL APPLICABILITY The present invention has industrial applicability in that it can provide a method for producing functional water with various properties using ozone microbubbles.

Claims

1. A method for producing functional water, comprising: step A of introducing ozone microbubbles into water containing a solid iron source and having a pH of 4.0 or less; and step B of increasing the pH of the water after step A to 7.0 or higher.

2. The method of claim 1, wherein a divalent manganese compound is dissolved during step A.

3. The manufacturing method according to claim 1, wherein the functional water has hump-shaped absorption peaks in the wavelength ranges around 270 nm and 370 nm in the difference spectrum obtained by an ultraviolet-visible-near-infrared spectrophotometer between the spectrum measured at pH 7.0 and the spectrum measured at pH 2.5 by lowering the pH of the functional water.

4. Functional water having a pH of 6.0 or higher, which has hump-shaped absorption peaks in the wavelength ranges around 270 nm and 370 nm in the difference spectrum obtained by an ultraviolet-visible-near-infrared spectrophotometer between the spectrum measured at pH 7.0 and the spectrum measured at pH 2.5 by lowering the pH of the functional water.

5. Use of the functional water according to claim 4 as an oxidizing agent.

6. Use of the functional water according to claim 4 as a disinfectant.

7. Use of the functional water according to claim 4 as a deodorizer.

8. Use of the functional water according to claim 4 as a biological activator.

9. Use of the functional water according to claim 4 as a hydrophilic agent.

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