JP2011224424A - Apparatus for treating water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing antibacterial treated water, which uses a photocatalytic reaction to kill bacteria in a solution and contains antibacterial constituents.SOLUTION: The apparatus includes: a photocatalytic filter 2 in a first stage to which oxidized titanium (IV) being chemically bonded halogens is fixed; and a section 4 for producing active substances in a second stage to which oxidized titanium (IV), including oxo acids and halogens, is fixed, wherein an ultraviolet lamp 8 irradiates the filter and the section respectively with light and the filter and the section contact with water to be treated containing sea water, resulting in killing bacteria in the first stage and producing antibacterial constituents in the second stage, such as halogen oxides like hypochlorous acids or active oxygen species like hydrogen peroxides.

Description

  The present invention relates to a water treatment apparatus that generates active oxygen species and halogen oxides having an ability to oxidize organic substances and kills microorganisms such as bacteria and plankton contained in water including seawater.

  Conventionally, an electrolyzed water generating device obtained by electrolyzing a chloride aqueous solution is known as an antibacterial treated water generating device used in this type of water treatment device. Water containing chloride ions is stored in a water tank and electrolyzed with an electrode installed in the water tank to generate chlorine from the anode. The generated chlorine is dissolved in water and converted to hypochlorous acid having antibacterial action. For example, an electrolyzed water generating device as shown in FIG. 3 is known as a conventional antibacterial treated water generating device (see, for example, Patent Document 1).

  This is because the first electrode 101 and the second electrode 102 are separated by an ion-permeable separation membrane 103, and the saline solution supplied to the first electrolytic cell 104 is electrolyzed by the first electrode 101, thereby providing antibacterial activity. It generates hypochlorous acid with action.

  Further, as another active substance generating device, a technique using discharge is known (see, for example, Patent Document 2).

  An apparatus for generating hydrogen peroxide which is one of the active oxygen species is shown in FIG. Hydrogen peroxide is generated by electric discharge using a mixed gas containing hydrogen and oxygen as a source gas. While adjusting the concentration of the source gas 201 to hydrogen and oxygen so as not to explode, the gas is introduced into the first discharge unit 202 and discharged, and then the second discharge unit while supplying oxygen from the oxygen supply port 203. It is introduced into 204 and discharged to obtain a mixture of hydrogen peroxide and hydrogen, oxygen or water. In this method, an active substance is generated in the gas phase. By trapping the obtained gas in the liquid phase, a liquid containing an antibacterial component can be obtained.

Japanese Patent No. 4249657 Japanese Patent Laid-Open No. 4-130002

  The conventional antibacterial treated water generator described in Patent Document 1 has a relatively simple structure, but the generated antibacterial component is mainly hypochlorous acid, which is oxidized compared to reactive oxygen species such as hydroxyl radicals. For bacteria with low strength and resistance, there is a problem that it is necessary to generate them at a high concentration, and the harmful effects of irritating odors are inevitable. For this reason, there is a demand for an antibacterial effect obtained by mixing antibacterial components having strong oxidizing power even at low concentrations with low odor. In addition, in the production of hypochlorous acid by electrolysis, there is a problem of producing trihalomethane, which is harmful to the human body as a by-product, and there are those that selectively generate effective components without generating harmful by-products. It has been demanded.

  Further, the conventional method for generating an active substance described in Patent Document 2 needs to supply oxygen and hydrogen as raw material gases, and requires gas storage means such as a cylinder. For this reason, in the case of continuous local use for a long period of time, it is always necessary to replenish the raw material gas, so that it is required to generate gas directly from air or the like without replenishing the raw material gas.

  Further, since discharge is used, there is a problem that various reactants are generated by reacting with the emitted electrons, and it is difficult to control the amount and type. Some active substances have a strong irritating odor such as ozone, and it is required to prevent the generation of such components selectively.

  The present invention solves such a conventional problem, and does not generate harmful by-products, can selectively generate effective components, and has little irritating odor without replenishing raw material gas. It is an object of the present invention to provide a water treatment apparatus equipped with an antibacterial treated water generation unit that can selectively generate active substances such as active oxygen species or halogen oxides directly.

  In order to achieve the above object, the water treatment apparatus of the present invention includes an active substance generating means that contains a photocatalyst and generates an active substance, a light source for irradiating the photocatalyst with excitation light, and for controlling the light source. Control means, wherein the photocatalyst contains halogen and oxo acid, and circulates water to be in contact with the active substance generating means to kill microorganisms in the water. This achieves the intended purpose.

  According to the present invention, titanium oxide (IV) containing oxo acid and halogen is irradiated with light containing ultraviolet rays, so that the oxo acid attached to titanium oxide (IV) is a photocatalyst of titanium oxide (IV). Even if there is no means for supplying source gas such as a cylinder in the reaction, by oxidizing water or oxygen dissolved in water, active substances such as hydrogen peroxide with less irritating odor and hypochlorous acid at low concentration can be obtained. Since it can produce | generate and supply, it has the effect | action of producing | generating antibacterial treated water with few irritation odors. Thereby, the effect that the compact water treatment apparatus with little irritating odor can be obtained is obtained.

  Furthermore, among active oxygen species generated on the surface of titanium oxide (IV), active substances with relatively long life such as hydrogen peroxide and hypochlorous acid are generated and increased, and hydrogen peroxide and hypochlorous acid are oxidized. It has the effect that it can be released from the titanium (IV) surface into the liquid phase. Therefore, the effect that the to-be-processed water can be maintained clean for a comparatively long time is acquired.

The conceptual diagram which shows the structure of the water treatment apparatus of embodiment of this invention The graph which shows the measurement result of the hypochlorous acid of Example 1 of this invention The block diagram which shows the conventional electrolyzed water generating apparatus Configuration diagram showing a conventional active substance generator

  The invention according to claim 1 of the present invention comprises an active substance generating means for generating an active substance containing a photocatalyst, a light source for irradiating the photocatalyst with excitation light, a control means for controlling the light source, And the photocatalyst contains halogen and oxo acid, and water to be treated is circulated so as to come into contact with the active substance generating means, thereby killing microorganisms in the water. By containing halogen in the photocatalyst, the amount of active substances such as reactive oxygen species generated by the photocatalytic reaction is increased, so that the effect of killing bacteria and plankton is enhanced. Thereby, size reduction of a photocatalyst and the light intensity of a light source can be reduced.

  Further, in the invention according to claim 2 of the present invention, a plurality of active substance generating means are provided, water to be treated is sequentially brought into contact with the plurality of active substance generating means, and oxo acid is contained in the active substance generating means provided in the subsequent stage. It is characterized by having been made. This has the effect of increasing the generation amount of relatively stable active oxygen species such as hydrogen peroxide compared to unstable active materials such as hydroxyl radicals generated by the photocatalyst and contains the active material in the liquid to be treated. Thus, the antibacterial action can be maintained for a certain period after the treatment. Moreover, by providing in a back | latter stage, it has the effect | action that it prevents that the active material which generate | occur | produced will be decomposed | disassembled with a photocatalyst, and can give an antimicrobial effect to a to-be-processed liquid.

  The invention according to claim 3 of the present invention is characterized in that at least a part of the halogen contained in the photocatalyst is chemically bonded to the photocatalyst. Thereby, it has the effect | action that a high killing effect is acquired by making halogen into a strong coupling | bonding to a photocatalyst.

  The invention according to claim 4 of the present invention is characterized in that the photocatalyst is titanium (IV) oxide. Titanium oxide (IV) has a large band gap, and has a function of obtaining a higher killing effect because light having a shorter wavelength and higher energy can be efficiently used as an excitation light source.

  The invention according to claim 5 of the present invention is characterized in that the halogen is fluorine. The high electronegativity of fluorine has the effect of facilitating the generation of active substances such as active oxygen species generated on the photocatalyst, and the photocatalytic activity can be enhanced.

  The invention according to claim 6 of the present invention is characterized in that the oxo acid is a phosphoric acid compound. By containing a phosphoric acid compound that is used as a hydrogen peroxide stabilizer, it has the effect of stably generating hydrogen peroxide by a photocatalytic reaction, and is a relatively stable active substance in the water to be treated. Hydrogen peroxide can be contained, and antibacterial action can be given to the water to be treated for a certain period.

  Further, the invention according to claim 7 of the present invention is characterized in that an aeration means for aeration of air to the water to be treated is provided in front of the oxo acid-containing active substance generation means. By providing a diffuser means in front of the active substance generating means, the water to be treated can contain a large amount of oxygen in advance, and when the water containing a large amount of oxygen comes into contact with the photocatalyst, a superoxide anion radical is obtained by a photocatalytic reaction. In addition, it can generate active oxygen species such as oxidization of chloride ions derived from seawater contained in the water to be treated to generate halogen oxides such as chlorine dioxide and hypochlorous acid. Have. Halogen oxides can provide an antibacterial action for a longer time in water.

  The invention according to claim 8 of the present invention is characterized in that the active substance generating means is constituted by immobilizing a photocatalyst on a base material. By molding the photocatalyst using a base material having a high degree of freedom in shape, the contact efficiency between the water to be treated and the photocatalyst can be increased, and the killing effect is enhanced.

  The invention according to claim 9 of the present invention is characterized in that the photocatalyst and the substrate are fixed using an inorganic binder. When an inorganic binder is used, it has the effect of increasing the strength for immobilizing the photocatalyst, and the durability can be enhanced.

  The invention according to claim 10 of the present invention is characterized in that the base material is ceramic or glass. It does not deteriorate due to the photocatalytic reaction and has an effect of enhancing durability.

  The invention according to claim 11 of the present invention is characterized in that the light source is a high-pressure UV lamp. Among the mercury emission lines, it contains both 254 nm ultraviolet light, which has a bactericidal effect, and 365 nm wavelength component, which has good excitation efficiency of titanium oxide (IV), so the photocatalytic and UV light killing effects are synergistic. Therefore, a high killing effect can be obtained.

  The invention according to claim 12 of the present invention is characterized in that the active substance generating means and the light source are provided inside a sealed casing, and the casing is provided with a water supply port and a drain port. is there. By continuously treating the water to be treated in a sealed space, it has an effect of preventing the entry of microorganisms from the outside air. Moreover, by preventing volatilization of the active substance, it is possible to suppress a decrease in the concentration of the active substance and maintain a high antibacterial action.

  The invention according to claim 13 of the present invention is characterized in that the casing is made of stainless steel. Since stainless steel is inactive to the active substance, it has the effect that the active substance is less likely to be reduced by decomposition, the light from the light source is reflected inside the housing, and the energy usage efficiency is increased, and the workability is good. When used in seawater, it is particularly resistant to corrosion and thus has an effect of increasing durability. Thereby, photocatalytic activity can be improved.

  The invention according to claim 14 of the present invention further comprises light detection means for detecting the intensity of the light source, and the control means controls the input voltage to the light source based on the intensity of the light source detected by the light detection means. It is characterized by a constant strength. The action of maintaining the photocatalytic activity by increasing the output of the light source when the scale is attached to the light source due to the heat emitted from the light source, the light transmittance decreases, and the light energy irradiated to the photocatalyst decreases. And can maintain a high killing effect.

  The invention according to claim 15 of the present invention is characterized in that the active substance generating means and the light source are detachable. When the performances of the light source and the active substance generating means are lowered, it is possible to easily replace it with a new one by making it detachable, and it is possible to maintain a high killing effect.

(Embodiment)
[Configuration of water treatment equipment using photocatalyst]
The conceptual diagram of the structure of the water treatment apparatus of this invention is shown in FIG.

  As shown in FIG. 1, the water treatment apparatus 1 includes a treatment unit 3 having a photocatalytic filter 2 that is an active substance generating means made of halogen-containing titanium oxide (IV), and an oxo acid and halogen-containing titanium oxide ( The active substance generating unit 4 which is an active substance generating means consisting of IV), an air diffuser pipe 5 which is an air diffuser, and an active substance supply unit 7 having a compressed air supply line 6 are formed.

  An ultraviolet lamp 8 as a light source for irradiating excitation light and an illuminance sensor 9 as a light detection means for detecting the intensity of ultraviolet light are adjacent to the photocatalyst of each unit and controlled from the outside. The intensity of the ultraviolet rays irradiated to the photocatalyst is controlled by means 10. Each unit is housed in a sealed housing 11. It is preferable that the photocatalyst and the light source have a detachable structure so that the photocatalyst and the light source can be replaced at the time of maintenance, and the casing 11 is open / closed or can be easily removed so that the replacement work can be easily performed.

  The housing 11 includes a water supply port 12 for introducing the liquid to be processed and a drain port 13 for discharging the liquid, so that the liquid to be processed can be easily introduced into and discharged from the unit. These units are configured by connecting a plurality of units in series or in parallel depending on the required processing capacity.

  The photocatalytic filter 2 is formed by forming a halogen-containing titanium (IV) oxide into a filter shape, and is, for example, fixed to a glass fiber filter using a binder and dried. The filter formed is positioned by the fixing member and placed in the flow path.

  The photocatalytic filter 2 is preferably arranged so as to be parallel along the flow path and adjusted with respect to the light source so that the photocatalytic filter 2 is efficiently irradiated with ultraviolet rays. Further, the interval of the photocatalytic filter 2 is determined from the killing ability and the treatment flow rate, the ultraviolet intensity, the ability of the pump for supplying the water to be treated, the passage resistance of the unit, the number, and the like. The thickness may be 5 cm to 10 cm, and preferably 1 cm to 3 cm.

  Similarly to the photocatalytic filter 2, the active substance generation unit 4 made of oxo acid and halogen-containing titanium oxide (IV) is formed by immobilizing a photocatalyst on a base material. Since the generation amount of the active substance can be increased by being close to the ultraviolet lamp 8, the active substance generation unit 4 is preferably arranged in the vicinity of the ultraviolet lamp 8.

  The diffuser pipe 5 provided in the active substance supply unit 7 including the active substance generating unit 4 is for dispersing a gas containing oxygen in the water to be treated in the form of fine bubbles, and is a porous body pipe, a mesh, or a nozzle called an ejector Etc.

  A compressed air supply line 6 is connected to the diffuser pipe 5 to supply a gas containing oxygen from outside the system. The air may be compressed by a pump or the like, or may be connected to a cylinder and supplied with the sealed gas. By mixing the gas into the water to be treated by the air diffuser 5, the gas can be refined, and a large amount of oxygen can be stably present in the liquid to be treated for a long time. The reaction can oxidize halogens such as chlorine present in seawater to produce halogen oxides such as hypochlorous acid and chlorine dioxide.

  These halogen oxides have a relatively long life of about 1 day, and can provide an antibacterial action even after the water to be treated is treated. Microorganisms are known to have bacterial spores and dormant cell states called cysts, but these are highly resistant to the external environment and survive even if treated. It may grow in later treated water. On the other hand, the growth of these microorganisms can be suppressed by supplying an active substance having a long life such as a halogen oxide into the water to be treated.

  The ultraviolet lamp 8 that is a light source for irradiating excitation light to titanium oxide (IV) is not particularly limited as long as it has an intensity from a wavelength of 250 nm to 400 nm. However, the ultraviolet lamp 8 has a strong emission peak in the wavelength range. The titanium oxide (IV) can be excited efficiently with respect to the input power. In order to excite the photocatalyst, light having a wavelength of about 400 nm or less is necessary. However, when ultraviolet light having a wavelength larger than the band gap is irradiated, an excess amount is not used for the photocatalytic reaction, and thus energy loss. It is considered that. For this reason, the efficiency that can be used in the photocatalytic reaction with respect to the energy of light input at a wavelength closer to 380 nm is increased.

  On the other hand, a wavelength of around 250 nm acts on nucleic acids of microorganisms such as bacteria and plankton, and a certain killing effect can be obtained without a photocatalyst. Low pressure mercury lamps, amalgam lamps, and the like that efficiently generate wavelengths in this range are used as germicidal lamps, and high killing performance can be obtained by using them together with photocatalytic reactions.

  However, in the case of sterilization using ultraviolet rays around 250 nm, it is known that there is a phenomenon of light recovery in which damaged microorganisms repair a damaged DNA and have a proliferative ability again. Therefore, it cannot be said that the germicidal lamp alone has sufficient killing performance, and it is necessary to use a photocatalyst in combination. By efficiently using these two wavelengths, the killing effect by the photocatalyst can be enhanced. For example, when a high-pressure mercury lamp is used, both a wavelength near 360 nm and a wavelength around 250 nm are included, and photocatalytic reaction and ultraviolet sterilization can be performed efficiently.

  When a straight tube type lamp is used as the shape of the ultraviolet lamp 8, it is possible to irradiate strong light over a wide range, and therefore it may be used when the area of the substrate is large. Further, ultraviolet rays emitted from the light source may be arranged so that a wide area can be irradiated by a mirror or a lens with little absorption.

  When the liquid to be treated is efficiently treated with the photocatalyst, the disposition effect varies depending on the arrangement of the photocatalytic filter 2 and the ultraviolet lamp 8, and therefore it is important to take an efficient arrangement. For example, in the case where the ultraviolet lamp 8 is a straight tube type, if the liquid to be processed is circulated along the longitudinal direction, the number can be minimized with respect to the required processing amount, so that the efficiency with respect to the power consumption is reduced. Can be raised.

  In order to detect the intensity of the ultraviolet rays irradiated to the photocatalyst, an illuminance sensor 9 sensitive to the ultraviolet rays is provided. The illuminance sensor 9 is, for example, a semiconductor type. In order to avoid direct contact with seawater, it is installed in the vicinity of the ultraviolet lamp 8 in a state of being enclosed in quartz glass or the like having transparency to ultraviolet rays. When the illuminance detected by the illuminance sensor 9 decreases, operation control is performed by the control means 10 so that the illuminance of ultraviolet rays emitted from the ultraviolet lamp 8 is maintained. For example, the control means 10 performs control such as increasing the voltage applied to the ultraviolet lamp 8, or removing the deposits by cleaning the system, or displaying that it is time to replace the ultraviolet lamp 8. Also good.

  A housing 11 is provided so as to surround the photocatalytic filter 2 and the ultraviolet lamp 8, thereby fixing the photocatalytic filter 2 and the ultraviolet lamp 8 and simultaneously forming a flow path. The inside of the housing 11 is preferably a mirror surface for reflecting ultraviolet rays.

  In addition, since it is in direct contact with seawater, which is the liquid to be treated, a liquid that is not easily affected by corrosion by seawater, is not altered by the oxidizing power of the produced antibacterial component, and is not altered by irradiated ultraviolet rays. A metal or inorganic material or a material coated with these can be used. If it is a metal, it is stainless steel, aluminum, copper or the like, and if it is an inorganic compound, ceramic or glass can be used. Stainless steel is preferred from the viewpoint of reflecting the light from the light source and increasing the photocatalytic reaction efficiency.

  The casing 11 is provided with a water supply port 12 for introducing the liquid to be treated and a drain port 13 for discharging the liquid. However, since the water to be treated to be supplied is conveyed by a pump, there is no leakage due to a structure such as a flange. It is preferable to be hermetically sealed and connected.

  The active substance generated by the water treatment apparatus of the present invention is an oxidizing agent having an action of reacting with an organic substance and oxidizing. As active substances, reactive oxygen species include hydroxyl radicals, superoxide anion radicals, singlet oxygen, hydrogen peroxide, ozone, and the like. These reactive oxygen species include a C—C bond (bonding energy of about 347 kJ / mol), a C—H bond (bonding energy of about 415 kJ / mol), or a C═C bond π bond ( It is known to break bonds such as a bond energy of about 285 kJ / mol) by an oxidation reaction.

  In order to break this bond, dissociation energy higher than the bond energy is required. For example, the hydroxyl radical, which is a strong active oxygen species, has an oxidation potential of about 2.8 V and a dissociation energy of about 504 kJ / mol, so that it can be oxidatively decomposed by breaking the C—C bond. Such an oxidizing agent has a property of being unstable and extremely short in life (about 1 millisecond or less) because of its large energy.

  On the other hand, in the case of hydrogen peroxide, the oxidation potential is 1.77 V and the dissociation energy is 319 kJ / mol. In this case, since it is lower than the energy for cutting the C—C bond, it cannot be cut, but the π bond of the C═C double bond can be cut. In addition, since the oxidation potential is low, the stability is increased as compared with the hydroxyl radical, so that the life is extended (about 1 hour or more). Such a substance is suitable when the active substance is allowed to act on a remote position such as a gas phase or a liquid phase.

  In addition, chloric acid compounds (eg, hypochlorous acid, chlorous acid, perchloric acid, chlorine dioxide, etc.), bromic acid compounds (eg, bromic acid, hypobromous acid, perbromic acid, etc.), iodic acid Halogen compounds such as system compounds (for example, iodic acid, periodic acid, etc.) also have an oxidizing power and are included in the active substance of the present invention. For example, the oxidation potential of hypochlorous acid is 1.5 V, and the dissociation energy is about 268 kJ / mol.

  These active substances react with microorganisms such as bacteria, fungi, or protozoa such as plankton, and oxidize all or part of them to exert antibacterial and killing effects.

  In the present invention, “antibacterial” refers to sterilizing and / or decomposing liquid phase bacteria, and preferably refers to reducing the concentration of bacteria in the liquid phase and / or inhibiting the growth of bacteria. Specifically, it means that the bacteria concentration can be reduced by two orders of magnitude or more from the initial concentration when the active substance and the bacteria contact for 24 hours or more. In the present invention, the microorganisms to be killed are not particularly limited, and examples include bacteria, molds, viruses, plankton, and the like. Examples of the bacteria include Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, MRSA, Vibrio parahaemolyticus, enterococci, cholera, cereus, and Klebsiella pneumoniae. In the case of seawater, there are animals or phytoplankton. Examples of animals include rotifers, shellfish and crustacean larvae. , Red algae, euglena and the like.

  In the present invention, the halogen compound contained in the liquid becomes a halogen oxide by a photocatalytic reaction, and an antibacterial action can be obtained. Although the detailed generation mechanism is not clear, it is presumed that the halogen oxide ions react with the hydroxyl radical or superoxide anion radical generated on the photocatalyst to form a halogen oxide. Examples of the halogen compound to be contained in the liquid include chlorides such as sodium chloride, potassium chloride, and magnesium chloride in the case of chlorine compounds.

  Moreover, in an iodine compound, potassium iodide etc. are mentioned. Examples of bromine compounds include bromides such as potassium bromide, calcium bromide, ammonium bromide, and sodium bromide. These are preferably reacted as an aqueous solution, and it is also effective to mix them in the reaction stock solution or to use those originally contained in the reaction stock solution. For example, tap water or chloride ions contained in seawater can be used.

  In the present invention, the oxo acid compound to be contained in the liquid is a compound having a hydroxyl group (OH) and an oxo group (C═O), which is present in an ionic state in the liquid and is generated on the surface of the photocatalyst. It has the effect of converting reactive oxygen species into a relatively stable state. The mechanism by which oxo acid converts radical substances into stable compounds is not clear, but oxygen-rich structures like oxo acids coordinate with radicals to convert them into more stable active substances. It is thought that it is done.

  Although it does not specifically limit as an oxo acid, A general oxo acid compound can be used. For example, when the oxo acid is a phosphate compound, zinc phosphate, aluminum phosphate, potassium phosphate, calcium phosphate, silver (I) phosphate, chromium (III) phosphate, cobalt phosphate, ferric phosphate, Titanium phosphate, iron phosphate (III), copper phosphate (II), lead phosphate (II), magnesium phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, sodium monohydrogen phosphate, diphosphoric acid phosphate Sodium hydrogen, lithium dihydrogen phosphate, triammonium phosphate, tripotassium phosphate, tricalcium phosphate, trisodium phosphate, trilithium phosphate, sodium ammonium hydrogen phosphate, calcium hydrogen phosphate, magnesium hydrogen phosphate, Diammonium hydrogen phosphate, dipotassium hydrogen phosphate, disodium hydrogen phosphate, polyphosphoric acid, ammonium polyphosphate Arm, potassium polyphosphate, sodium polyphosphate, metaphosphate, aluminum metaphosphate, potassium metaphosphate, sodium metaphosphate, sodium hexametaphosphate, adenosine triphosphate, adenosine diphosphate, nucleic acid compounds, and the like.

  Further, when the oxo acid is a carbonate compound, ammonium carbonate, potassium carbonate, calcium carbonate, sodium carbonate, lead carbonate, barium carbonate, manganese carbonate, lithium carbonate, magnesium carbonate, ammonium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate, Examples include strontium carbonate, cesium carbonate, cerium carbonate, iron carbonate, and copper carbonate.

  When the oxo acid is a sulfuric acid compound, sulfuric acid, zinc sulfate, aluminum sulfate, ammonium sulfate, potassium sulfate, calcium sulfate, ammonium hydrogen sulfate, potassium hydrogen sulfate, sodium hydrogen sulfate, tin (II) sulfate, strontium sulfate, cesium sulfate , Ferrous sulfate, ferrous sulfate, ferric sulfate, ferric sulfate, titanium sulfate, copper (II) sulfate, sodium sulfate, magnesium sulfate, manganese sulfate, lithium sulfate and the like.

  When the oxo acid is a nitrate compound, nitric acid, zinc nitrate, ammonium nitrate, potassium nitrate, chromium nitrate (III), cobalt nitrate (II), cesium nitrate, iron (II) nitrate, copper (II) nitrate, nickel nitrate, Examples thereof include barium nitrate, magnesium nitrate, manganese nitrate, and lithium nitrate. On the other hand, those that are not oxidatively decomposed by the photocatalyst are preferable, and phosphoric acid, sulfuric acid, carbonic acid, nitric acid, and boric acid are exemplified.

  For example, when phosphoric acid is used as the oxo acid, it can be used as an aqueous solution having an appropriate concentration using a phosphate or hydrogen phosphate. Moreover, phosphoric acid compounds, such as polyphosphoric acid and metaphosphoric acid, can be used similarly. All have a plurality of oxo groups in the structure.

  In the present invention, the type of antibacterial component to be generated can be selectively generated according to the type and amount of oxo acid and halogen contained. For example, when phosphate is used as an oxo acid compound, it has been confirmed that hydrogen peroxide is generated as an active substance. Moreover, when sodium chloride is used as a halogen compound, it has been confirmed that hypochlorous acid is generated.

  What is necessary is just to control the halogen containing state and ratio by the target substance to generate | occur | produce. In addition, it is not preferable to obtain the same effect with a halogen oxo acid generated from a halogen without containing an oxo acid because the amount of halogen oxo acid generated is small.

  In the present invention, “at least a part of halogen is chemically bonded to titanium (IV) oxide” means that titanium (IV) oxide and at least a part of halogen are chemically bonded. Preferably, it refers to a state in which titanium (IV) oxide and halogen are bonded at an atomic level, not supported or mixed, and more preferably it means that titanium (IV) oxide and halogen are ion-bonded. . In the present invention, “chemically bonded halogen” refers to, for example, a halogen that is difficult to elute in water among the halogens contained in the halogen-containing titanium oxide (IV). In addition, when two or more types of halogens are contained, the effect can be obtained as long as one or more of them are chemically bonded.

  In the present invention, examples of the halogen include fluorine, iodine, bromine and chlorine. For example, when fluorine is used as the halogen, the fluorine content may be 1.5% to 3.5% by weight from the viewpoint of enhancing the amount of active substance generated and antibacterial performance during light irradiation. preferable. The fluorine content in the fluorine-containing titanium oxide (IV) can be determined by a spectrophotometric analysis method (JIS K 0102).

  Examples of the photocatalyst in the present invention include titanium (IV) oxide, tungsten oxide, strontium titanate, niobium oxide, and tantalum oxide. Of these, titanium (IV) oxide is preferable from the viewpoint of the strength of activity.

  Examples of titanium oxide (IV) include anatase-type titanium oxide (IV), rutile-type titanium oxide (IV), and brookite-type titanium oxide (IV). Since high photocatalytic activity is obtained, anatase-type titanium oxide (IV) is preferred. In the present invention, “anatase-type titanium oxide (IV)” refers to titanium oxide (IV) in which a diffraction peak appears at a diffraction angle 2θ = 25.5 degrees in powder X-ray diffraction spectrum measurement (use electrode: copper electrode). That means.

  As titanium oxide (IV), in addition to titanium dioxide, hydrous titanium oxide, hydrated titanium oxide, metatitanic acid, orthotitanic acid, titanium hydroxide, oxygen-deficient titanium oxide, nitrogen-substituted titanium oxide, sulfur-substituted titanium oxide Etc. The crystal form is not particularly limited as long as it has photocatalytic activity, and any of amorphous, anatase, rutile, and brookite forms may be used. There is no problem even if components having different crystal forms such as a combination of rutile type and anatase type titanium oxide (IV) are combined.

  Titanium (IV) oxide is often in the form of powder, but a titanium (IV) thin film may be formed by oxidizing a metal surface such as a titanium plate. In addition, a titanium thin film may be formed by coating titanium alkoxide or the like and performing heat treatment. A titanium (IV) oxide film may be formed by spraying titanium powder on a metal surface or the like.

  Further, it is not limited at all to coat the surface of titanium oxide (IV) with a metal such as Pt, Pd, Rh, Ru, Au, Ag, Cu, Fe, or Ni. Further, there is no limitation to using a photocatalyst whose surface has an impurity metal such as Cr or V to increase the absorption wavelength of light.

Titanium oxide (IV) preferably has a specific surface area of 200 to 350 m ² / g, more preferably 250 to 350 m ² / g. Here, the specific surface area in the present invention is a surface area value per gram of titanium (IV) powder measured by the BET method (nitrogen adsorption / desorption method). When the specific surface area is 200 m ² / g or more, the contact area with the object to be decomposed can be increased.

  The amount of halogen chemically bonded to titanium oxide (IV) is such that titanium oxide (IV) photocatalyst is dispersed in water and pH is adjusted to 3 or less or pH to 10 or more with a pH adjusting agent (for example, hydrochloric acid or aqueous ammonia). It can be calculated by subtracting the elution amount from the total amount of halogen contained in the halogen-containing titanium oxide (IV) by measuring the elution amount of halogen in water by colorimetric titration or the like.

  The chemical bond is preferably an ionic bond. When the chemical bond is an ionic bond, the halogen and titanium oxide (IV) are strongly bonded, and for example, the ionic bond between titanium (IV) oxide and halogen can improve the antibacterial activity and the photocatalytic reaction promoting action. And can be analyzed by a photoelectron spectrometer. For example, when the halogen is fluorine, when the halogen-containing titanium oxide (IV) is analyzed with a photoelectron spectrometer, the peak top of the fluorine 1s orbital (F1s) shows a spectrum in the range of 683 eV to 686 eV. Say. This is because the value of the peak top of titanium fluoride in which fluorine and titanium are ion-bonded is within the above range.

[Method for producing oxo acid and halogen-containing titanium oxide (IV)]
The oxo acid and halogen-containing titanium oxide (IV) of the present invention may be any one in which titanium oxide (IV) and a halogen are chemically bonded and an oxo acid and a halogen different from the halogen are attached. A halogen-containing titanium oxide (IV) can be produced in the step, and in the second step, oxo acid and other halogens can be further added. When titanium oxide (IV) chemically bonded with oxo acid is not used, it can be carried out only in the first step.

  The halogen-containing titanium oxide (IV), which is the first step, is, for example, mixing an aqueous dispersion of titanium oxide (IV) with an n-butylamine adsorption amount of 8 μmol / g or less and a halogen compound, When the pH of the mixed solution exceeds 3, the pH is adjusted to 3 or less using an acid, whereby the titanium (IV) oxide and the halogen compound are reacted in the mixed solution, and the reaction is performed. And washing the reaction product obtained to obtain a halogen-containing titanium oxide (IV) in which at least a part of the halogen is chemically bonded to the titanium oxide (IV). . As the anatase type titanium oxide (IV) having an adsorption amount of n-butylamine of 8 μmol / g or less, for example, SSP-25 manufactured by Sakai Chemical Industry Co., Ltd. can be used. CSB-M manufactured by Kogyo Co., Ltd. can be used.

  Although it does not specifically limit as a halogen compound, A general halogen compound can be used. When the halogen compound is a fluorine compound, examples thereof include ammonium fluoride, potassium fluoride, sodium fluoride, and hydrofluoric acid. Among these, ammonium fluoride, potassium fluoride, and hydrofluoric acid are preferable. . When the halogen compound is an iodine compound, examples thereof include hydrogen iodide, periodic acid, and ammonium iodide. When the halogen compound is a bromine compound, examples thereof include hydrobromic acid and ammonium bromide. When a halogen compound is a chlorine compound, hydrochloric acid, sodium chloride, and hypochlorous acid are mentioned.

  The measuring method of the adsorption amount of n-butylamine per 1 g of titanium (IV) oxide is as follows. That is, 1 g of titanium oxide (IV) sample dried at 130 ° C. for 2 hours was precisely weighed in a 50 mL conical flask with a stopper, and 30 mL of a 0.003 normal concentration n-butylamine solution diluted with methanol was added thereto. Add. Next, this is subjected to ultrasonic dispersion for 1 hour and then allowed to stand for 10 hours, and 10 mL of the supernatant is collected. Then, the collected supernatant is subjected to potentiometric titration using a 0.003 normal concentration perchloric acid solution diluted with methanol, and the adsorption amount of n-butylamine can be determined from the titration amount at the neutralization point at that time. .

  Moreover, titanium oxide (IV) can carry out light irradiation and the scattering prevention of a photocatalyst effectively by carry | supporting to a base material. In the case of supporting on a base material, the halogen-containing titanium oxide (IV) is prepared first, and after supporting on the base material, it is prepared by attaching an oxo acid and an additional halogen. The substrate is not particularly limited, but a general filter substrate can be used, and examples thereof include metals, plastics, synthetic resin fibers, natural fibers, wood, paper, glass, ceramics, and ceramics and glass are suitable. Yes. When plastic or paper is used as the substrate, titanium (IV) oxide may be supported by coating the surface of the substrate with silicone, fluororesin, silica, or the like.

  The shape of the substrate is not particularly limited, but when it is formed into a filter shape such as a plate shape, a net shape, a honeycomb shape, a fiber shape, a bead shape, a slit shape, or a foam shape, light irradiation and contact with the liquid to be processed are performed efficiently. be able to. A plate-like filter is preferably provided with an opening such as a punching shape in which holes are formed in a plate, a knitted shape in which fibers are knitted, and a non-woven shape in which fibers are bonded. If it is plate-shaped, pressure loss may be reduced by expanding the surface area of the filter by folding the plate into a pleat shape.

  When a glass fiber fabric is used for the substrate, durability against light and radiation is strong, and it is less susceptible to chemical corrosion due to an acidic binder than organic synthetic fibers and paper. Moreover, since glass fiber has a light transmittance and a light-scattering property, when irradiating light to halogen-containing titanium oxide (IV), light can be irradiated efficiently. Examples of the material of the glass fiber include quartz glass, E glass, C glass, S glass, and A glass. Although a fiber shape is not specifically limited, It is preferable to form with the fiber bundle which bundled multiple short fiber glass which has a diameter of 4-9 micrometers rather than a single fiber. The fiber bundle can be used by bundling an arbitrary number of about 50 to 6400. When titanium oxide (IV) is supported on a fiber bundle in which a plurality of short fiber glasses are bundled, titanium (IV) oxide particles enter or adhere between the fibers and are fixed. Compared with the case where titanium oxide (IV) is supported on the surface of a thick single fiber, titanium (IV) oxide can be held between the fibers, so that the supported amount can be increased. In addition, the titanium oxide (IV) particles that have entered between the fibers are firmly fixed by being sandwiched between the fibers, and even when an impact is applied from the outside, the impact is transmitted through the fiber so that it does not easily fall off. Obtainable.

When using a binder, alkali silicates composed of silicates such as Na ₂ O, K ₂ O and LiO ₂ , inorganic colloids such as silica sol, alumina sol and zirconia sol, alkoxides such as silica, silicon and titanium and their hydrolysis Such as things. In addition, since an alkali component such as Na lowers the crystallinity of titanium oxide (IV) and may deteriorate the performance, the binder is preferably SiO ₂ as a main component. A hydrolyzate of alkoxides is preferable.

  Examples of silicon alkoxides include tetraethoxysilane and polymers thereof such as methoxypolysiloxane, ethoxypolysiloxane, butoxypolysiloxane, and lithium silicate. Examples of titanium alkoxides include tetrapropoxytitanium and polymers thereof. Is mentioned. These metal alkoxides are hydrolyzed with water and acid and can be used as a binder.

  The binder is preferably acidic, and examples thereof include a product obtained by hydrolyzing silicon, titanium and the like with an acid, acidic silica sol, alumina sol and the like. When hydrolyzing silicon, titanium or the like with an acid, the pH may be adjusted to 1 to 5 using hydrochloric acid, sulfuric acid or the like. When silica sol is used, one having a pH of 2 to 4 and a particle size of about 10 to 50 nm is preferable. When a silica sol having a neutral or alkaline pH is used, gelation is often caused when a halogen-containing titanium (IV) oxide is added, and it is often difficult to uniformly support the substrate.

When a cation component such as Na, K, NH ₄ is contained in the binder, the antibacterial performance may be lowered due to the progress of the reaction with the halogen and the adsorption to the titanium (IV) oxide surface. The cation component should be as low as possible. For example, when Na is contained in the binder solution, the Na concentration is preferably greater than 0 wt% and not more than 0.05 wt% as Na ₂ O.

The basis weight of the glass fiber fabric is preferably 10 to 900 g / m ² , and in order to facilitate the production, it is preferable to select 100 to 400 g / m ² . The weaving method may be any weaving method such as plain weaving, twill weaving, satin weaving, tangle weaving or imitation weaving, but imitation weaving is preferred from the viewpoint of shape stability. The yarn density is preferably 20-40 fibers / 25 mm in the length / width fiber bundle, 0.1-2 mm in thickness, and 100 NN / 25 mm or more in tensile strength.

  Examples of the method of supporting the halogen-containing titanium oxide (IV) on the substrate include dip coating and spraying, but any means may be used as long as the halogen-containing titanium oxide (IV) can be immobilized on the substrate. If the carrying amount is not enough in one treatment, a plurality of treatment steps may be repeated. Moreover, after carrying | supporting, a binder may be shrunk by heating at about 50-700 degreeC with a dryer for about 0.01-5 hours, and it may fix firmly to a base material at 90-400 degreeC for 2 hours. Is more preferred. In the case of performing such heat drying treatment, it is desirable that the main component of the base material is composed of glass or ceramics.

  The particle diameter of the halogen-containing titanium oxide (IV) is preferably smaller than the fiber diameter. Since the halogen-containing titanium oxide (IV) is smaller than the diameter of the fiber, the halogen-containing titanium oxide (IV) can easily enter the stitches and overlapping portions between the fibers, and an effect of being firmly fixed can be obtained. As a result, the supported amount of halogen-containing titanium oxide (IV) can be increased. The particle diameter of the halogen-containing titanium (IV) oxide is about 6 to 100 nm as the primary particle diameter, but in actuality, the primary particles often aggregate to form secondary particles of about 0.1 to 100 μm. The particle diameter of the halogen-containing titanium oxide (IV) referred to here indicates a state of secondary particles, and it is necessary that the halogen-containing titanium oxide (IV) is easy to enter the fiber stitches and overlapping portions when dispersed in the knitted fabric. .

  When adding an oxo acid and an additional halogen to the halogen-containing titanium oxide (IV), the halogen-containing titanium oxide (IV) prepared in the first step is added with an oxo acid or a different type of halogen from the halogen. It can be produced by contacting with an aqueous solution.

  The oxo acid is used for the addition after mixing at a concentration capable of being dissolved in a suitable solvent. For example, it is used by dissolving in purified water to a concentration of about 0.01% to 10% by weight.

  In addition, a halogen compound of a type different from the halogen to be chemically bonded can be mixed and simultaneously added to the solution. Examples of the halogen at this time include chlorides such as sodium chloride, potassium chloride, and magnesium chloride in the case of chlorine compounds. Moreover, in an iodine compound, potassium iodide etc. are mentioned. Examples of bromine compounds include bromides such as potassium bromide, calcium bromide, ammonium bromide, and sodium bromide. These are also used by mixing and dissolving a soluble amount in an oxoacid solution. For example, it can be dissolved and used at a concentration of about 0.01% to 10% by weight.

  Examples of the method of attaching oxo acid to titanium (IV) oxide or halogen-containing titanium (IV) include dip coating and spraying, but any means may be used as long as it can adhere to halogen-containing titanium oxide (IV). After contacting titanium oxide (IV) with an oxoacid solution, if powdered, it is centrifuged and filtered, and if fixed to a substrate, it is pulled up and dried at a low temperature of 100 ° C. or lower. Eliminate liquid residue. The oxo acid and halogen adsorbed in this way are not chemically bonded to titanium (IV) oxide, but are presumed to be in a state of being randomly adsorbed on the pores and surface of titanium oxide (IV). The

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is limited to the following description and is not interpreted at all.

Example 1
<1>. Preparation of oxo acid and halogen-containing titanium oxide (IV) Titanium oxide (IV) (trade name: SSP-25, manufactured by Sakai Chemical Industry Co., Ltd., anatase type, particle size: 5 to 10 nm, specific surface area: 270 m ² / g or more ) Was added to titanium (IV) oxide so that the concentration thereof was 150 g / L, and this was stirred to prepare a titanium (IV) oxide dispersion. To this titanium oxide (IV) dispersion, hydrofluoric acid (made by Wako Pure Chemical Industries, special grade) corresponding to 3% by weight in terms of fluorine (element) is added to titanium oxide (IV), and the pH is 3 And kept at 25 ° C. for 60 minutes. The resulting reaction product was washed with water. The washing with water was performed until the electric conductivity of the filtrate collected by filtering the reaction product was 1 mS / cm or less. And this was dried at 130 degreeC in the air for 5 hours, and the fluorine-containing titanium oxide (IV) was prepared.

<2>. Preparation of filter carrying halogen-containing titanium oxide (IV) Obtained halogen-containing titanium oxide (IV) and silica-based binder (Na component is 0.05 wt% or less as Na ₂ O concentration, pH = 3, SiO ₂ concentration 20 wt% silica sol) and purified water were mixed and dispersed and mixed in a ball mill for 24 hours to prepare a slurry. The finished slurry is dipped in a glass fiber fabric with an opening ratio of 15% as a base material, impregnated with halogen-containing titanium oxide (IV), air blown to remove excess liquid, and then dried in a 120 ° C dryer for 30 minutes. To prepare a filter containing halogen-containing titanium oxide (IV). The same dipping operation was repeated, so that the combined amount of the halogen-containing titanium oxide (IV) and the binder was 500 g / m ² . The glass fiber fabric used as the base material of the filter had a weight per unit area of 354 g / m ² , a yarn density of 11 × 3/25 mm (same for vertical and horizontal), and a thickness of 0.42 mm. The aperture ratio of the produced filter was about 15%.

<3>. Preparation of Oxo Acid and Halogen-Containing Titanium (IV) Oxide Filter The obtained halogen-containing titanium (IV) oxide filter was impregnated with 50 mM phosphate buffered saline, which is a source of oxo acid and halogen, and then pulled up. It was left to stand for 2 hours in a drying oven at 0 ° C. and dried to obtain an oxoacid and halogen-containing titanium oxide (IV) filter.

<4>. Measurement of generation amount of antibacterial component The produced photocatalytic filter was cut into a strip shape having a length of 5 cm and a width of 2 cm, and inserted into a glass test tube having a diameter of 3 cm and a depth of 10 cm. Further, 10 ml of 50 mM phosphate buffered saline (PBS) as a reaction stock solution was added to the test tube. In order to supply air to the phosphate buffered saline, an air pipe was provided in a test tube with a Teflon (registered trademark) tube having a diameter of 3 mm. At the tip of the pipe, a ceramic porous air diffuser was installed to release fine bubbles. It should be noted that the tip of the pipe was disposed below the photocatalytic filter. In this state, air was supplied into the liquid at a flow rate of 0.1 ml / min from the piping with a diaphragm pump.

The outside of the test tube was irradiated with black light at 5 mW / cm ² so as to sandwich the test tube, and air was circulated for 12 hours to generate an active substance in the liquid. After 12 hours, the reaction solution in the test tube was collected, and hypochlorous acid as an antibacterial component in the liquid was quantified. For the measurement of hypochlorous acid, a free chlorine measuring reagent (HACH) by the DPD method was used, and the free chlorine concentration was measured with a direct reading water quality analyzer. The result is shown in FIG.

(Example 2)
As Example 2, the amount of active substance generated was measured for those reacted in the same manner as in Example 1 except that distilled water was used instead of the phosphate buffered saline of the reaction solution. The result is shown in FIG.

(Example 3)
As Example 3, the amount of active substance generated was measured in the same manner as in Example 1, except that the reaction was performed in the dark without being irradiated with ultraviolet rays. The result is shown in FIG.

  The filter of Example 1 detected about 0.17 mg / L hypochlorous acid after 12 hours. On the other hand, it was below the lower limit of detection (less than 0.01 mg / L) under the conditions of Example 2, and about 0.01 mg / L under the conditions of Example 3. It was confirmed that hypochlorous acid, an antibacterial component, was released from the filter by irradiating the photocatalytic filter with light containing a halogen compound sodium chloride in the reaction solution and bubbling the gas. .

  It is possible to provide a method for killing microorganisms in water including seawater using a photocatalyst, and it can be applied to uses for purifying seawater such as ship ballast water and power plant cooling water.

DESCRIPTION OF SYMBOLS 1 Water treatment apparatus 2 Photocatalyst filter 3 Processing unit 4 Active substance production | generation part 5 Aeration pipe 6 Compressed air supply line 7 Active substance supply unit 8 Ultraviolet lamp 9 Illuminance sensor 10 Control means 11 Case 12 Water supply port 13 Drainage port 101 1st Electrode 102 Second electrode 103 Ion permeable diaphragm 104 First electrolytic cell 201 Source gas 202 First discharge part 203 Oxygen supply port 204 Second discharge part

Claims (15)

An active substance generating means that contains a photocatalyst and generates an active substance; a light source for irradiating the photocatalyst with excitation light; and a control means for controlling the light source, wherein the photocatalyst generates halogen and oxo acid. A water treatment apparatus comprising: water to be treated that circulates water to be in contact with the active substance generating means to kill microorganisms in the water. An active substance generating means for generating an active substance containing a photocatalyst containing halogen, a light source for irradiating the photocatalyst with excitation light, and a control means for controlling the light source, the active substance generating This is a water treatment device that circulates water to be in contact with the means and kills microorganisms in the water. A plurality of active substance generating means are provided, and the water to be treated is sequentially brought into contact with the plurality of active substance generating means. A water treatment apparatus characterized in that an oxo acid is contained in an active substance generating means provided in a subsequent stage. The water treatment apparatus according to claim 1 or 2, wherein at least a part of the halogen contained in the photocatalyst is chemically bonded to the photocatalyst. The water treatment device according to any one of claims 1 to 3, wherein the photocatalyst is titanium (IV) oxide. The water treatment apparatus according to any one of claims 1 to 4, wherein the halogen is fluorine. The water treatment apparatus according to any one of claims 1 to 5, wherein the oxo acid is a phosphoric acid compound. The water treatment device according to any one of claims 1 to 6, further comprising an aeration unit for aerating air to the water to be treated in front of the active substance generation unit containing oxo acid. The water treatment apparatus according to any one of claims 1 to 7, wherein the active substance generating means is configured by immobilizing a photocatalyst on a base material. The water treatment apparatus according to claim 8, wherein the photocatalyst and the base material are fixed using an inorganic binder. The water treatment apparatus according to claim 8 or 9, wherein the base material is ceramic or glass. The water treatment apparatus according to any one of claims 1 to 10, wherein the light source is a high-pressure UV lamp. The water treatment apparatus according to any one of claims 1 to 11, wherein the active substance generating means and the light source are provided inside a sealed casing, and the casing is provided with a water supply port and a drain port. The water treatment apparatus according to claim 12, wherein the housing is made of stainless steel. 2. A light detection means for detecting the intensity of the light source, wherein the input voltage to the light source is controlled by the control means according to the intensity of the light source detected by the light detection means to make the light intensity constant. The water treatment apparatus in any one of 13 thru | or 13. The water treatment apparatus according to claim 1, wherein the active substance generating means and the light source are detachable.

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