Ozone water generation device and ozone water generation method

Abstract

Provided are an ozone water generation device and an ozone water generation method which make it possible to increase the amount of ozone generated in water and maintain the concentration of generated ozone. An ozone water generation device according to the present invention is characterized by comprising: a nitric acid ion removal device that removes, from supplied water, at least nitric acid ions among the ions contained in the water, thereby generating conditioned water in which the nitric acid ions are adjusted to a prescribed concentration or lower; a nanobubble water generation device that is disposed in the conditioned water, that receives supply of air or oxygen, and that produces, in the conditioned water, nanobubbles of the air or oxygen, thereby generating nanobubble water in which the nanobubbles are mixed in the conditioned water; and an ultraviolet light irradiation device that irradiates the nanobubbles contained in the nanobubble water or the air or oxygen supplied to the nanobubble water generation device with ultraviolet light and changes the same to ozone in the conditioned water, thereby generating nanobubble ozone water which contains ozone nanobubbles.

Description

Ozone water generator and ozone water generation method

[0001] The present invention relates to an ozone water generator and an ozone water generator.

[0002] Ozone has strong oxidizing properties and possesses sterilizing, disinfecting, and deodorizing effects, making it widely used in medical and industrial fields. Because ozone is unstable in its gaseous state and to improve ease of handling, it is generally effective to use ozonated water, which is ozone gas dissolved in water.

[0003] A method for generating ozonated water and an apparatus for generating ozonated water are described, for example, in Patent Document 1. Patent Document 1 describes a method for generating ozonated water that differs from the method of obtaining ozonated water by dissolving ozone gas in water. More specifically, Patent Document 1 describes a method for generating ozonated water characterized by mixing oxygen with water to form oxygen nanobubble water, and irradiating this oxygen nanobubble water with ultraviolet light to generate nanobubble ozonated water containing ozone nanobubbles. It is stated that the wavelength of the ultraviolet light irradiated onto the oxygen nanobubble water is preferably 130 nm to 200 nm, and more preferably 185 nm.

[0004] Japanese Patent Publication No. 2011-200778

[0005] Since ozone is harmful to the human body, it is necessary to prevent the release of ozone into the atmosphere when generating ozonated water. Furthermore, in order to enhance the sterilization, disinfection, and deodorizing effects of ozonated water, it is important to increase the ozone concentration in the ozonated water and to maintain the ozone concentration of the generated ozonated water. In the technology described in Patent Document 1, ozone exists as highly stable nanobubbles in water. Therefore, a certain degree of effectiveness can be expected in maintaining the ozone concentration. On the other hand, there was room for further improvement in the method of mixing air with water to form air nanobubble water and then irradiating this air nanobubble water with ultraviolet light to increase the ozone concentration in the water.

[0006] The object of the present invention is to provide an ozone water generation method and an ozone water generation apparatus that can produce ozone water with a high ozone concentration in nanobubble water of air or oxygen and maintain that ozone concentration.

[0007] An ozone water generator provided according to one aspect of the present invention comprises: a nitrate ion removal device that produces adjusted water in which nitrate ions are adjusted to a predetermined concentration or lower by removing at least nitrate ions from the ions contained in the supplied water; a nanobubble water generator that is placed in the adjusted water and, upon receiving a supply of air or oxygen, generates nanobubbles of air or oxygen in the adjusted water to produce nanobubble water in which nanobubbles are mixed with the adjusted water; and an ultraviolet irradiation device that irradiates nanobubbles contained in the nanobubble water, or air or oxygen supplied to the nanobubble water generator with ultraviolet light, and converts them into ozone in the adjusted water to produce nanobubble ozone water containing nanobubbles of ozone.

[0008] Furthermore, an ozone water generation method provided in another aspect of the present invention includes: a nitrate ion removal step of generating adjusted water in which nitrate ions are adjusted to a predetermined concentration or lower by removing at least nitrate ions from the ions contained in the supplied water; a nanobubble water generation step of generating nanobubbles in the adjusted water by receiving air or oxygen and generating nanobubbles of air or oxygen in the adjusted water; and an ultraviolet irradiation step of generating nanobubble ozone water containing ozone nanobubbles by irradiating the nanobubbles contained in the nanobubble water or the air or oxygen supplied to the adjusted water with ultraviolet light and converting them into ozone in the adjusted water.

[0009] According to each aspect of the present invention, nitrate ions in the water are removed so that the concentration of nitrate ions in the water falls below a predetermined concentration. This reduces the absorption of ultraviolet light by nitrate ions and increases the amount of ultraviolet light that reaches the nanobubbles. Therefore, the ozone concentration in the water can be increased. Furthermore, since ozone is generated in the water as nanobubbles, the ozone concentration can be maintained.

[0010] Figure 1 is a schematic diagram of an ozone water generator according to the first embodiment. Figure 2 is a diagram showing the absorption spectra of oxygen molecules and ozone. Figure 3 is a diagram showing the absorption spectrum of water. Figure 4 is a graph showing the ozone concentrations of tap water, pure water, and filtered water. Figure 5 is a diagram showing the transmission spectra of tap water, pure water, and filtered water. Figure 6 is a graph showing the absorption spectrum of nitrate ions. Figure 7 is a graph showing the absorption spectrum of sodium. Figure 8 is a graph showing the absorption spectrum of sulfate ions. Figure 9 is a graph showing the absorption spectrum of chloride ions. Figure 10 is a graph showing the absorption spectrum of calcium. Figure 11 is a flow chart of the method for generating ozone water according to the first embodiment. Figure 12 is a schematic diagram of an ozone water generator according to the second embodiment. Figure 13 is a schematic diagram of an ozone water generator according to the third embodiment.

[0011] The ozone water generator and ozone water generation method according to this embodiment will be described in detail below with reference to the drawings.

[0012] <<First Embodiment>> Figure 1 is a schematic diagram of an ozone water generator 2 according to the first embodiment. As shown in Figure 1, the ozone water generator 2 comprises a pipe 4 and a nitrate ion removal device 6 connected to the downstream side of the pipe 4. Water 1 is supplied to the nitrate ion removal device 6 through the pipe 4. Water 1 is, for example, tap water or well water. The pipe 4 is made of a metal such as stainless steel. However, the materials of the water 1 and the pipe 4 are not limited to these.

[0013] The nitrate ion removal device 6 includes, for example, a cylindrical container (not shown) and an anion exchange resin (not shown) filled in the container. The inside of the container is filled with multiple granular anion exchange resins with gaps that serve as water channels. Water 1 entering the nitrate ion removal device 6 passes through the gaps between the anion exchange resins in the container.

[0014] The anion exchange resin contains at least nitrate ions (NO) from among the ions contained in water. ３ －) can be removed. Among the ions contained in the water 1 supplied to the nitrate ion removal device 6, anions including nitrate ions are removed by the anion exchange resin by hydroxide ions (OH － ) will be replaced with.

[0015] The nitrate ion removal device 6 removes nitrate ions (NOx) contained in water 1. ３ － ) to a predetermined concentration (1 mg CaCO2) ３ Adjusted water 3 is produced, adjusted to a concentration of less than or equal to ( / L). The reason for adjusting the nitrate ions to a predetermined concentration or less using the nitrate ion removal device 6 will be explained later.

[0016] The configuration of the nitrate ion removal device 6 is not limited to the above configuration. The nitrate ion removal device 6 can have any configuration as long as it can produce adjusted water 3 in which nitrate ions are adjusted to a predetermined concentration or below by removing nitrate ions from water 1. The nitrate ion removal device 6 only needs to be able to remove at least nitrate ions from the ions contained in water 1 to a predetermined concentration or below, and may also have the ability to remove ions other than nitrate ions.

[0017] The nitrate ion removal device 6 may, for example, use a reverse osmosis membrane (RO membrane) instead of anion exchange resin to adjust the nitrate ions to a predetermined concentration or lower. In this case, the housing 10 is divided into two tanks by the reverse osmosis membrane (not shown). When the supplied water 1 passes through the reverse osmosis membrane, only water molecules can pass through, so water from which nitrate ions have been removed is obtained. However, when a reverse osmosis membrane is used, ions other than nitrate ions (sodium, sulfate ions, chloride ions, etc.) and minerals (calcium, etc.) are also almost completely removed and lost.

[0018] One end of a pipe 8 is connected to the nitrate ion removal device 6. The other end of the pipe 8, on the downstream side, is connected to a housing 10. The adjusted water 3 produced by the nitrate ion removal device 6 is contained in the housing 10 via the pipe 8. The housing 10 is made of a cylindrical member made of, for example, ozone-resistant stainless steel or fluororesin (Teflon®). However, the material and shape of the housing 10 are not limited to these.

[0019] Inside the conditioning water 3 of the housing 10, a nanobubble water generator 12 is disposed. The nanobubble water generator 12 has, for example, a porous body (not shown) having innumerable pores. Examples of the porous body include ceramics such as alumina (Al ２ O ３ ), and silica (SiO ２ ).

[0020] One end of a pipe (supply pipe) 14 is connected to the nanobubble water generator 12. The other end of the pipe 14 is connected to a pump 16. Air or oxygen is supplied from the pump 16 to the nanobubble water generator 12 through the pipe 14. The air or oxygen supplied to the nanobubble water generator 12 becomes bubbles (nanobubbles) 5 having a minute diameter when passing through the porous body of the nanobubble water generator 12, and is supplied to the conditioning water 3 in the housing 10. Thereby, nanobubble water 7 in which the nanobubbles 5 are mixed into the conditioning water 3 is generated. The diameter of the nanobubbles 5 is 10 nm or more and 100 μm or less.

[0021] Note that the diameter of the nanobubbles is measured by a nanoparticle tracking analysis (NTA) method (for example, NanoSite NS300 of Malvern Analytical). By this method, laser light is irradiated onto particles in water, and scattered light when hitting the nanobubbles is measured to determine the particle diameter.

[0022] The ozone water generator 2 has an ultraviolet irradiation device 18. The ultraviolet irradiation device 18 generates ultraviolet light (vacuum ultraviolet light) 9 having a wavelength of 190 nm or more and 210 nm or less. The ultraviolet irradiation device 18 can use, for example, a device including a xenon discharge tube and a phosphor applied to the surface of the xenon discharge tube. The phosphor absorbs light generated from the xenon discharge tube and is excited to emit light having a wavelength of 190 nm or more and 210 nm or less. However, the configuration of the ultraviolet irradiation device 18 is not limited to this. The reason for setting the wavelength of the ultraviolet light to 190 nm or more and 210 nm or less will be described later.

[0023] The ultraviolet irradiation device 18 is positioned so that ultraviolet light 9 is irradiated onto the nanobubbles 5 contained in the nanobubble water 7 generated by the nanobubble water generator 12. In this embodiment, the ultraviolet irradiation device 18 is housed in a waterproof case (not shown) made of, for example, quartz glass, fluororesin, or silicone resin, and is positioned inside the housing 10.

[0024] The ultraviolet light 9 generated from the ultraviolet irradiation device 18 is irradiated onto the nanobubbles 5 in the nanobubble water 7, and the oxygen (O) contained in the nanobubbles 5 is irradiated. ２ ) is ozone (O ３ This transforms into ozone, generating ozone. This results in the production of ozonated water 13 (nanobubble ozonated water) containing ozone nanobubbles 11.

[0025] One end of the piping 20 is connected to the housing 10. The other end of the piping 20, on the downstream side, is exposed to the outside of the ozone water generator 2. The ozone water 13 generated by the ozone water generator 2 is released to the outside through the piping 20.

[0026] Next, we will explain why it is preferable to set the wavelength of ultraviolet 9 to 190 nm or more and 210 nm or less. Figure 2 shows the absorption spectra of oxygen molecules and ozone. As shown in Figure 2, the light absorption rate (absorption cross-section in Figure 2) of oxygen molecules is large in the wavelength range of 140 nm to 210 nm (the range indicated by the arrow in Figure 2). For this reason, it is thought that oxygen absorbs more light and more ozone is generated in this wavelength range.

[0027] On the other hand, when the wavelength exceeds 210 nm, ozone absorbs light more readily, making it easier for ozone to absorb light and decompose. Therefore, to efficiently convert oxygen into ozone, it is considered effective to irradiate oxygen with light of a wavelength between 140 nm and 210 nm.

[0028] Figure 3 shows the absorption spectrum of water. As shown in Figure 3, the light absorption rate by water changes significantly at a wavelength of 190 nm. That is, the light absorption rate increases sharply at shorter wavelengths below 190 nm, and decreases significantly in the region between 190 nm and 500 nm. In other words, light transmission increases significantly at wavelengths between 190 nm and 500 nm. Therefore, it is thought that more light with wavelengths between 190 nm and 500 nm reaches oxygen in water.

[0029] From the above, it can be said that the wavelength of light that can maximize ozone generation in water is between 190 nm and 210 nm. More preferably, the wavelength of ultraviolet light is between 190 nm and 200 nm.

[0030] Next, we will explain why the nitrate ion removal device 6 reduces the nitrate ion concentration to below a predetermined level. Figure 4 is a graph showing the ozone concentrations of tap water, pure water, and filtered water. Filtered water is tap water that has been passed through a filter equipped with a commercially available ion exchange resin (containing a mixture of cation exchange resin and anion exchange resin). Nanobubbles were generated in each of the tap water, pure water, and filtered water that had passed through the ion exchange resin, and ultraviolet light with a wavelength of 190 nm to 210 nm was irradiated with a UV lamp for 5 minutes. After that, the ozone concentrations of the tap water, pure water, and filtered water were measured. Indigo carmine spectrophotometry was used to measure the ozone concentration.

[0031] As shown in Figure 4, the ozone concentration measurements revealed that pure water had a concentration of 2.04 mg / L, while filtered water had a concentration of 1.09 mg / L. On the other hand, tap water was below the detection limit of 0.25 mg / L.

[0032] Figure 5 is a diagram showing the transmission spectra of tap water, pure water, and filtered water. As shown in Figure 5, when checking the transmission spectra, both pure water and filtered water show peaks at wavelengths between 190 nm and 210 nm. On the other hand, tap water does not show a peak at wavelengths between 190 nm and 210 nm. From these results, it is inferred that impurities (ions and minerals) contained in tap water hinder the transmission of light at wavelengths between 190 nm and 210 nm, inhibiting the generation of ozone.

[0033] Table 1 is a graph showing the results of component analysis of tap water, pure water, and filtered water. The component analysis was carried out by Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

[0034]

[0035] As shown in Table 1, the contents of nitrate ions, sulfate ions, calcium, and magnesium contained in tap water are low in both pure water and filtered water. Therefore, it is presumed that these substances affect the transmission at wavelengths of 190 - 210 nm. Also, chloride ions and sodium, which are contained more in filtered water than in tap water, are presumed to affect the transmission at wavelengths of 190 - 195 nm because the peak at wavelengths of 195 - 200 nm is larger in filtered water than in tap water.

[0036] Figure 6 is a graph showing the absorption spectrum of nitrate ions, Figure 7 is a graph showing the sodium absorption spectrum, Figure 8 is a graph showing the sulfate ion absorption spectrum, Figure 9 is a graph showing the chloride ion absorption spectrum, and Figure 10 is a graph showing the calcium absorption spectrum. Note that in Figures 6, 7, and 10, multiple graphs with different ion contents are shown together. As shown in Figure 6, it can be seen that nitrate ions and sodium have particularly large absorption at wavelengths between 190 nm and 210 nm.

[0037] On the other hand, as shown in FIGS. 7 to 10, sulfate ions, chloride ions, and calcium have absorption peaks in a wide range other than wavelengths of 190 to 210 nm. As shown in FIG. 5, although the peak on the long wavelength side of the transmission spectrum varies in intensity among tap water, pure water, and filtered water, there is no significant difference as large as that at wavelengths of 190 to 210 nm. Therefore, it is inferred that the components affecting the transmission spectrum at wavelengths of 190 nm or more and 210 nm are nitrate ions and sodium rather than sulfate ions, chloride ions, and calcium.

[0038] From the above examination results, when generating ozone water, by reducing nitrate ions in the supplied water to a predetermined concentration (1 mg CaCO ３ / L) or less, the transmittance of ultraviolet rays having wavelengths of 190 nm or more and 210 nm or less to water can be increased, and the amount of ultraviolet rays 9 reaching the nanobubbles 5 can be further increased. Therefore, the amount of ozone generated in water can be increased.

[0039] Also, since sodium also affects the transmission spectrum at wavelengths of 190 nm or more and 21 nm, it is preferably adjusted to a concentration below a predetermined value. Specifically, the sodium concentration is preferably 90 mg CaCO ３ / L or less, and more preferably 15 mg CaCO ３ [[ID=]12] / L or less. Sodium ions (Na ＋ ) can be almost removed by using a mixture in which a cation exchange resin is further filled in the nitrate ion removal device 6 in addition to the above-mentioned anion exchange resin. In this case, among the ions contained in the water 1 supplied to the nitrate ion removal device 6, the sodium ions, which are cations, are exchanged with hydrogen ions (H ＋ ) by the cation exchange resin, and the sodium ions (Na ＋ ) are adsorbed by the cation exchange resin and can be removed or reduced to a concentration below a predetermined value.

[0040] From the above, if the nitrate ion removal device 6 is filled with, for example, an anion exchange resin that removes the nitrate ions, which have the greatest impact, as shown in Figure 5, it is possible to change the filtered water containing a large amount of sodium ions into water that can transmit ultraviolet light of wavelengths between 190 nm and 210 nm, compared to tap water which is almost impermeable to ultraviolet light of wavelengths between 190 nm and 210 nm. As a result, as shown in Figure 4, it is possible to produce filtered water with an ozone concentration 6.8 times that of tap water (= 1.69 mg / L ÷ 0.25 mg / L), and water with an ozone concentration comparable to that of pure water that does not contain nitrate ions or sodium ions.

[0041] Furthermore, if cation exchange resin is also filled into the nitrate ion removal device 6 in addition to anion exchange resin, sodium ions can also be removed. As shown in Figure 5, the transmittance of pure water containing almost no nitrate or sodium ions at wavelengths of 190 nm to 210 nm can be made even higher than the transmittance of filtered water containing a large amount of sodium ions. However, the ozone concentration of the pure water was 1.2 times that of the filtered water (= 2.04 mg / L ÷ 1.69 mg / L), showing a slight improvement compared to filtered water with a large amount of sodium ions remaining, but the effect was not as dramatic as that of filtered water from which a large amount of nitrate ions had been removed.

[0042] Therefore, by using a nitrate ion removal device 6 filled only with anion exchange resin, the transmittance of the water at wavelengths of 190 nm to 210 nm increases, allowing ultraviolet light at wavelengths of 190 nm to 210 nm to pass through the water, ozonating the air or oxygen within the nanobubbles and increasing the ozone concentration of the nanobubble ozonated water. Furthermore, by filling the nitrate ion removal device 6 with both anion exchange resin and cation exchange resin, the sodium ions, which have the second highest influence, can be adjusted to a predetermined concentration or lower, making it possible to further increase the ozone concentration.

[0043] The filtered water produced using the commercially available ion exchange resin used in the first embodiment was effective in reducing nitrate ions, sulfate ions, calcium, and magnesium, but chloride ions and sodium ions increased. Generally, ion exchange resins containing both anion exchange resin and cation exchange resin should reduce or remove both chloride ions and sodium ions, but it is presumed that differences in performance among commercially available ion exchange resins will result in differences in the composition of the filtered water. In other words, commercially available ion exchange resins may not reduce other components such as nitrate ions in addition to chloride ions and sodium ions. Therefore, it is important to know which components the anion exchange resin or cation exchange resin can remove or reduce.

[0044] The nitrate ion removal device 6 must be able to adjust the nitrate ion concentration to a predetermined level or lower by removing at least nitrate ions. Furthermore, if the nitrate ion removal device 6 is composed solely of anion exchange resin, the anion exchange resin must be capable of adjusting the nitrate ion concentration to a predetermined level or lower. Moreover, even if the nitrate ion removal device 6 is composed of both anion exchange resin and cation exchange resin, the anion exchange resin must be able to adjust the nitrate ion concentration to a predetermined level or lower. Furthermore, if the nitrate ion removal device 6 includes a reverse osmosis membrane, the reverse osmosis membrane must be able to adjust the nitrate ion concentration to a predetermined level or lower.

[0045] Anion exchange resins are suitable for removing nitrate and sulfate ions, but to remove nitrate ions, which have the greatest impact on UV transmission in tap water, a strongly basic anion exchange resin with, for example, a quaternary ammonium group is better than a weakly basic anion exchange resin with, for example, a primary or secondary amino group. Cation exchange resins are suitable for removing or reducing sodium and calcium to below a certain concentration, but to remove sodium, which has the second greatest impact on nitrate ions, a strongly acidic cation exchange resin with, for example, a sulfonic acid group is better than a weakly acidic cation exchange resin with, for example, a carboxylic acid group. Furthermore, to remove or reduce nitrate ions and sodium, which have a significant impact on UV transmission, to below a certain concentration, it is better to use both strongly basic anion exchange resins and strongly acidic cation exchange resins.

[0046] Figure 11 is a flowchart of the method for generating ozonated water according to the first embodiment. As shown in Figure 11, the method for generating ozonated water according to this embodiment includes an ion removal step S1, a nanobubble water generation step S2, and an ultraviolet irradiation step S3.

[0047] In the ion removal step S1, nitrate ions are removed from the water 1 using the nitrate ion removal device 6, thereby adjusting the nitrate ion concentration to below a predetermined level. In the nanobubble water generation step S2, nanobubbles of air or oxygen are generated in the adjusted water, producing nanobubble water containing air or oxygen nanobubbles. In the ultraviolet irradiation step S3, ultraviolet light is irradiated onto the air or oxygen nanobubbles contained in the nanobubble water, producing nanobubble ozonated water containing ozone nanobubbles.

[0048] <<Second Embodiment>> Figure 12 is a schematic diagram of the ozone water generator 30 according to the second embodiment. The difference between the ozone water generator 30 shown in Figure 12 and the ozone water generator 2 according to the first embodiment is that an ultraviolet irradiation device 46 is arranged in the piping (supply pipe) 42 that connects the nanobubble water generator 40 and the pump 44.

[0049] In this embodiment, since the ultraviolet irradiation device 46 is located in the piping 42, ultraviolet light 9 is irradiated onto the air or oxygen supplied from the pump 44 to the nanobubble water generator 40. The air or oxygen irradiated with ultraviolet light 9 is converted into ozone 15 in the piping 42. Then, when the ozone 15 is supplied to the nanobubble water generator 40, ozone nanobubbles 11 are generated in the adjusted water 3. As a result, ozonated water 13 is produced.

[0050] The other components of the ozone water generator 30 according to this embodiment (piping 32, nitrate ion removal device 34, piping 36, housing 38, nanobubble water generator 40, pump 44, piping 48) are the same as those of the ozone water generator 2 according to the first embodiment (piping 4, nitrate ion removal device 6, piping 8, housing 10, nanobubble water generator 12, pump 16, piping 20). The ozone water generator 30 according to this embodiment can also obtain the same effects as the ozone water generator 2 according to the first embodiment.

[0051] <<Third Embodiment>> Figure 13 is a schematic diagram of the ozone water generator 50 according to the third embodiment. The difference between the ozone water generator 50 shown in Figure 13 and the ozone water generator 2 according to the first embodiment and the ozone water generator 30 according to the second embodiment is that it has a container 68 and an ultraviolet reflector 72.

[0052] In this embodiment, nanobubble water 7 generated by the nanobubble generator 60 is stored in a container 68 through piping 66. The container 68 is made of the same material as the housing 58, for example, and has a larger volume than the housing 58. However, the configuration of the container 68 is not limited to this.

[0053] The container 68 contains an ultraviolet irradiation device 70 and an ultraviolet reflecting material 72 that reflects ultraviolet rays 9 irradiated from the ultraviolet irradiation device 70. The ultraviolet reflecting material 72 is made of a material such as aluminum. The ultraviolet irradiation device 70 and the ultraviolet reflecting material 72 are arranged so that nanobubble water 7 is supplied between the ultraviolet irradiation device 70 and the ultraviolet reflecting material 72.

[0054] The other components of the ozone water generator 50 according to this embodiment (piping 52, nitrate ion removal device 54, piping 56, housing 58, nanobubble generator 60, piping 62, pump 64, piping 74) are the same as those of the ozone water generator 2 according to the first embodiment (piping 4, nitrate ion removal device 6, piping 8, housing 10, nanobubble water generator 12, piping 14, pump 16, piping 20).

[0055] According to the ozone water generator 50 of this embodiment, the amount of ultraviolet light 9 reaching the nanobubbles 5 contained in the nanobubble water 7 can be increased. This makes it possible to increase the amount of ozone generated.

[0056] According to the embodiments described above, nitrate ions in the water are removed so that their concentration falls below a predetermined level. This reduces the absorption of ultraviolet light by nitrate ions and increases the amount of ultraviolet light that reaches the nanobubbles. Therefore, the amount of ozone generated in the water can be increased. Furthermore, since the ozone is generated in the water as nanobubbles, the ozone concentration can be maintained.

[0057] The ozonated water produced by the ozonated water generator and ozonated water generation method according to this embodiment contains a high concentration of ozone and can maintain its ozone concentration over a long period of time. Therefore, it can be used in a variety of applications, such as sterilization devices, semiconductor cleaning devices, and vegetable freshness preservation devices.

[0058] Furthermore, even water containing many different ions and minerals, such as tap water, can be used to produce ozonated water by removing the ions using a nitrate ion removal device. Therefore, for example, by installing the aforementioned ozonated water generator on a household tap, nanobubble ozonated water can be easily obtained at home.

[0059] Furthermore, the structures, methods, etc., of the embodiments and modifications described above may be modified and implemented without departing from the scope of the present invention.

[0060] 1 Water 3 Adjusted water 5 Nanobubbles (air or oxygen nanobubbles) 7 Nanobubble water 9 Ultraviolet light 11 Nanobubbles (ozone nanobubbles) 13 Ozone water 15 Ozone 2 Ozone water generator 4 Piping 6 Nitrate ion removal device 8 Piping 10 Housing 12 Nanobubble generator 14 Piping (supply pipe) 16 Pump 18 Ultraviolet irradiation device 20 Piping 30 Ozone water generator 32 Piping 34 Nitrate ion removal device 36 Piping 38 Housing 40 Nanobubble generator 42 Piping (supply pipe) 44 Pump 46 Ultraviolet irradiation device 48 Piping 50 Ozone water generator 52 Piping 54 Nitrate ion removal device 56 Piping 58 Housing 60 Nanobubble generator 62 Piping (supply pipe) 64 Pump 66 Piping 68 Container 70 Ultraviolet irradiation device 72 Ultraviolet reflecting material 74 Piping

Claims

1. An ozone water generator comprising: a nitrate ion removal device that produces adjusted water in which nitrate ions are adjusted to a predetermined concentration or below by removing at least nitrate ions from the ions contained in the supplied water; a nanobubble water generator that is placed in the adjusted water and, upon receiving a supply of air or oxygen, generates nanobubbles of air or oxygen in the adjusted water, thereby producing nanobubble water in which the nanobubbles are mixed with the adjusted water; and an ultraviolet irradiation device that irradiates the nanobubbles contained in the nanobubble water, or the air or oxygen supplied to the nanobubble water generator, with ultraviolet light, thereby converting them into ozone in the adjusted water, thereby producing nanobubble ozone water containing nanobubbles of ozone.

2. The ozone water generator according to claim 1, characterized in that the wavelength of the ultraviolet light is 190 nm or more and 210 nm or less.

3. The ozone water generator according to claim 1, characterized in that the nitrate ion removal device adjusts the sodium concentration of the adjusted water to a predetermined concentration or less by further removing sodium from the water.

4. The ozone water generator according to claim 1, characterized in that the ultraviolet irradiation device is positioned to irradiate the nanobubble water generated by the nanobubble water generator with ultraviolet light.

5. The ozone water generator according to claim 1, wherein the nanobubble water generator placed in the adjusted water is connected to a supply pipe that supplies air or oxygen to the nanobubble water generator, and the ultraviolet irradiation device is positioned to irradiate the air or oxygen in the supply pipe with ultraviolet light.

6. The ozone water generator according to claim 5, characterized in that the ultraviolet irradiation device is located in the portion of the supply pipe that is situated in the adjusted water.

7. The ozone water generator according to claim 1, further comprising a container for storing the nanobubble water, wherein the ultraviolet irradiation device is positioned to irradiate the nanobubbles contained in the nanobubble water stored in the container with ultraviolet light.

8. The ozone water generator according to claim 1, further comprising an ultraviolet reflecting material that reflects the ultraviolet light irradiated by the ultraviolet irradiation device, wherein the ultraviolet irradiation device and the ultraviolet reflecting material are arranged such that the nanobubble water is supplied between the ultraviolet irradiation device and the ultraviolet reflecting material.

9. The ozone water generator according to any one of claims 1 to 8, wherein the ultraviolet irradiation device comprises a xenon discharge tube and a phosphor disposed on the surface of the xenon discharge tube, and the phosphor absorbs light emitted by the xenon discharge tube and emits ultraviolet light.

10. The predetermined concentration of the nitrate ion is 1 mg CaCO₃ ３ An ozone water generator according to any one of claims 1 to 8, characterized in that it is / L.

11. The predetermined concentration of sodium is 90 mg CaCO ３ The ozone water generator according to claim 3, characterized in that it is / L.

12. The ozone water generator according to any one of claims 1 to 8, characterized in that the water contains magnesium and calcium.

13. The ozone water generator according to any one of claims 1 to 8, characterized in that the nitrate ion removal device consists only of an anion exchange resin.

14. The ozone water generator according to claim 13, characterized in that the anion exchange resin can adjust at least nitrate ions to a predetermined concentration or less.

15. The ozone water generator according to any one of claims 1 to 8, characterized in that the nitrate ion removal device includes an anion exchange resin and a cation exchange resin.

16. The ozone water generator according to claim 15, characterized in that the anion exchange resin can adjust at least nitrate ions to a predetermined concentration or less.

17. The ozone water generator according to any one of claims 1 to 8, characterized in that the nitrate ion removal device includes a reverse osmosis membrane.

18. The ozone water generator according to claim 17, characterized in that the reverse osmosis membrane can adjust at least nitrate ions to a predetermined concentration or less.

19. The ozone water generator according to any one of claims 1 to 8, characterized in that the diameter of the nanobubbles is 10 nm or more and 100 μm or less.

20. A method for generating ozonated water, comprising: an ion removal step of generating adjusted water in which nitrate ions are adjusted to a predetermined concentration or lower by removing nitrate ions contained in supplied water; a nanobubble water generation step of generating nanobubbles of air or oxygen in the adjusted water by receiving air or oxygen and generating nanobubbles of air or oxygen in the adjusted water; and an ultraviolet irradiation step of generating nanobubble ozonated water containing nanobubbles of ozone by irradiating the nanobubbles contained in the nanobubble water or the air or oxygen supplied to the adjusted water with ultraviolet light and converting them into ozone in the adjusted water.

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