Air purification device

Abstract

To provide a space purification device that can stably generate a desired amount of hypochlorous acid gas over a long period of time. [Solution] The air purification device includes an electrolytic cell that generates hypochlorous acid, and Cl - The system comprises a supply tank for supplying an aqueous solution to an electrolytic cell, an electrolytic anode, a reversible common electrode, and a regenerative cathode provided in the electrolytic cell, a supply cathode provided in the supply tank, and an anion exchange membrane provided to connect the electrolytic cell and the supply tank. A first aqueous solution is electrolyzed without a membrane using the electrolytic anode and the common electrode used as the cathode to generate hypochlorous acid, and a purification operation is performed in which air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with the hypochlorous acid. If the oxide film on the common electrode decreases due to the purification operation, the membrane-free electrolysis is stopped and the system switches to a regeneration operation to regenerate the oxide film, and the oxide film on the surface of the common electrode is regenerated by applying a voltage between the common electrode, which is set as the anode, and the regenerative cathode.

Description

[Technical Field]

[0001] This invention relates to a space purification device. [Background technology]

[0002] Patent Document 1 discloses an air purification device that uses hypochlorous acid produced by electrolyzing an aqueous sodium chloride solution to remove bacteria, fungi, viruses, odors, and other substances contained in the air. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-174032 [Overview of the project] [Problems that the invention aims to solve]

[0004] The inventors discovered that when conventional air purification devices are miniaturized, the electrodes are also miniaturized, and electrolysis for hypochlorous acid generation is repeated over a long period of time. This leads to a decrease in the amount of hypochlorous acid produced due to a reduction in the oxide film covering the cathode, which lowers the electrolysis efficiency.

[0005] This invention was made in view of the above problems, and provides a space purification device that can stably generate a desired amount of hypochlorous acid gas over a long period of time. [Means for solving the problem]

[0006] The air purification device according to the present invention comprises: an electrolytic cell that stores a first aqueous solution containing chloride ions and generates hypochlorous acid by non-diaphragm electrolysis of the first aqueous solution; a supply tank that stores a second aqueous solution containing chloride ions and supplies chloride ions contained in the second aqueous solution to the first aqueous solution by diaphragm electrolysis; an electrolytic anode provided in the electrolytic cell and used for non-diaphragm electrolysis and diaphragm electrolysis; a reversible common electrode composed of an electrode material and an oxide film covering the electrode material and used for non-diaphragm electrolysis and regeneration treatment of the oxide film; a regeneration cathode used for regeneration treatment of the oxide film; a supply cathode provided in the supply tank and used for diaphragm electrolysis; and an anion exchange membrane provided to connect the electrolytic cell and the supply tank and allowing anions to pass through based on the voltage applied between the electrolytic anode and the supply cathode. Hypochlorous acid is generated by membrane-free electrolysis of the first aqueous solution using an electrolytic anode and a shared electrode used as the cathode, and a purification operation is performed in which air introduced from the outside space flows through the electrolytic cell and is released into the outside space along with the hypochlorous acid. If the oxide film covering the electrode material of the shared electrode used as the cathode decreases as a result of this purification operation, the membrane-free electrolysis is stopped at least and the system is switched to a regeneration operation to regenerate the oxide film. In the regeneration operation, the polarity of the shared electrode used as the cathode is reversed to make it the anode, and a voltage is applied between the shared electrode used as the anode and the regeneration cathode to regenerate the oxide film on the surface of the shared electrode. [Effects of the Invention]

[0007] The present invention provides a space purification device capable of stably generating a desired amount of hypochlorous acid gas over a long period of time. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front cross-sectional view of a space purification device according to an embodiment. [Figure 2] Figure 2 is a functional block diagram of the current control unit according to the embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. Note that the xyz coordinates shown in the diagrams are for convenience in explaining the positional relationships of the components. Unless otherwise specified, the positive z-axis direction is vertically upward. Also, the xy-plane is the horizontal plane and is consistent across all drawings.

[0010] <Embodiment> Figure 1 is a front cross-sectional view of an air purification device 1 according to an embodiment. The air purification device 1 performs membraneless electrolysis of a first aqueous solution L1 containing chloride ions in an electrolytic cell 10, which will be described later, to generate and volatilize hypochlorous acid. The air purification device 1 removes bacteria, fungi, viruses, or odors contained in the air in the space outside the housing C that constitutes the air purification device 1 by releasing the generated hypochlorous acid into the space outside the air purification device 1. In addition, membrane electrolysis is performed to supply chloride ions contained in a second aqueous solution L2 stored in a supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 10 by permeating the anion exchange membrane 30, in order to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by membraneless electrolysis.

[0011] The air purification device 1 is installed indoors. Preferably, the installation location of the air purification device 1 is a place where airflow can occur. More specifically, the installation location of the air purification device 1 is indoors. Specific examples of installation locations for the air purification device 1 include, for example, the inside of an air conditioner, the inside of a bathroom heater / dryer, around a fan, around a circulator, around a ceiling fan, inside a humidifier, inside a dehumidifier, inside an air purifier, and on a desk.

[0012] As shown in Figure 1, the air purification device 1 comprises a housing C, an electrolytic cell 10, a supply tank 20, an anion exchange membrane 30, and a current control unit 40.

[0013] The housing C is a box-shaped member that stores the electrolytic cell 10, the supply tank 20, the anion exchange membrane 30, and the current control unit 40. That is, the space purification device 1 is a unit integrated by the housing C. The space purification device 1 has a small size. When the shape of the housing C is a rectangular parallelepiped, it is, for example, about 10 cm × 7 cm × 4 cm.

[0014] The electrolytic cell 10 is a tank for storing the first aqueous solution L1 containing chloride ions and subjecting the first aqueous solution L1 to diaphragm-free electrolysis to generate hypochlorous acid. The supply tank 20 is a tank for storing the second aqueous solution L2 containing chloride ions and supplying the chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by diaphragm electrolysis. More specifically, the chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 by diaphragm electrolysis through the anion exchange membrane 30 provided so as to connect the electrolytic cell 10 and the supply tank 20. The current control unit 40 controls the diaphragm-free electrolysis, the diaphragm electrolysis, and the regeneration treatment of the oxide film formed on the surface of the common electrode 12 described later. Details of the electrolytic cell 10, the supply tank  20, and the anion exchange membrane 30 will be described later.

[0015] When assuming continuous use for 8 hours every day for one year, the volume of each of the electrolytic cell 10 and the supply tank 20 is preferably such that, for example, the volume of the supply tank 20 is about 12 times or more that of the electrolytic cell 10. By setting such a volume ratio, the supply tank 20 can store the second aqueous solution L2 containing a sufficient amount of chloride ions necessary for supplying the first aqueous solution L1 of the electrolytic cell 10. Therefore, chloride ions can be stably supplied from the second aqueous solution L2 stored in the supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 10. The amount of the first aqueous solution L1 stored in the electrolytic cell 10 is, for example, about 2 mL to 10 mL.

[0016] When viewed from the front, in order from the negative side of the x-axis, the electrolytic cell 10, the supply tank 20 The components are arranged in order. The anion exchange membrane 30 is positioned between the electrolytic cell 10 and the supply tank 20, connecting the electrolytic cell 10 and the supply tank 20. For example, if the surfaces of the electrolytic cell 10 and the supply tank 20 facing each other are formed by a frame-shaped member, the anion exchange membrane 30 may be positioned so as to be fitted into the frame-shaped member. The current control unit 40 is positioned at any location within the housing C, but is not limited to this position; it may be positioned outside the housing C and connected wirelessly or by other means.

[0017] The details of the electrolytic cell 10, the supply tank 20, and the anion exchange membrane 30 will be explained below using Figure 1, and the details of the current control unit 40 will be explained mainly using Figure 2.

[0018] [Electrolytic cell 10] The electrolytic cell 10 is a cell for storing a first aqueous solution L1 containing chloride ions and for generating hypochlorous acid by diaphragm-free electrolysis of the first aqueous solution L1. The electrolytic cell 10 may have a box-like shape, but any shape that can store the first aqueous solution L1 is acceptable. Figure 1 shows the electrolytic cell 10 with the first aqueous solution L1 stored inside. The amount of the first aqueous solution L1 stored in the electrolytic cell 10 is, for example, about 2 mL to 10 mL. The first aqueous solution is, for example, an aqueous solution in which an electrically conductive electrolyte is dissolved, i.e., an electrolyte, and specifically a dilute chloride aqueous solution having a predetermined chloride ion concentration. More specifically, the first aqueous solution L1 is, for example, a dilute sodium chloride aqueous solution or a dilute potassium chloride aqueous solution.

[0019] The "predetermined chloride ion concentration" of the first aqueous solution L1 includes both a chloride ion concentration having a predetermined numerical range and a chloride ion concentration having a predetermined numerical value. More specifically, the chloride ion concentration of the first aqueous solution L1 may be, for example, 17 mmol / L to 1500 mmol / L, or 171 mmol / L. In other words, for example, the concentration of a dilute sodium chloride aqueous solution or a dilute potassium chloride aqueous solution may be 17 mmol / L to 1500 mmol / L, or 171 mmol / L. By setting the predetermined chloride ion concentration to the numerical range or numerical value, it is possible to generate hypochlorous acid necessary for air purification while simultaneously suppressing the generation of chlorine that may be generated.

[0020] The electrolytic cell 10 includes an electrolytic anode 11, a shared electrode 12, a regenerative cathode 13, an air supply unit 14, a blower pipe 15, an internal space 16 on the electrolytic cell side, a water recovery unit 17, and a discharge port 18. The electrolytic cell 10 may further include a water level detection unit 19.

[0021] The electrolytic anode 11 is an electrode used in both non-diaphragm electrolysis and diaphragm electrolysis. An insoluble electrode may be used as the electrolytic anode 11. More specifically, as the electrolytic anode 11, for example, a platinum-iridium titanium electrode, a platinum electrode, a ruthenium titanium electrode, or an iridium titanium oxide electrode may be used. As shown in Figure 1, when the electrolytic anode 11 is a plate-shaped electrode, it has two plate-shaped surfaces, one of which is positioned to face the anion exchange membrane 30 described later, and the other surface is positioned to face the common electrode 12. In this specification, "facing" includes not only cases where the surfaces are directly in front of each other, but also cases where they are partially in front of each other.

[0022] The shared electrode 12 is composed of an electrode material and an oxide film covering the electrode material, and is used for membrane-free electrolysis and regeneration of the oxide film. More specifically, the shared electrode 12 is a reversible electrode, used as a cathode in membrane-free electrolysis and as an anode by reversing its polarity in regeneration operation. Regeneration operation refers to the regeneration of the oxide film on the shared electrode 12, which will be described in detail later. As shown in Figure 1, when the shared electrode 12 is a plate-shaped electrode, it has two plate-shaped surfaces, one of which is positioned to face the electrolytic anode 11, and the other surface is positioned to face the regeneration cathode 13.

[0023] A specific example of the shared electrode 12 is chloric acid (H), which can be produced as a byproduct of non-diaphragm electrolysis. Examples of electrodes that have reducing properties for ClO3 and have an oxide film formed on their surface include titanium electrodes, iron electrodes, tin electrodes, nickel electrodes, or alloys of the aforementioned metals. Examples of cases where the common electrode 12 is a metal alloy include a nickel-titanium alloy or a titanium electrode with tin oxide as a catalyst. Iron electrodes with an oxide film formed on them contain both FeO and Fe2O3. Details of the reduction of chloric acid will be described later in conjunction with the explanation of the purification operation.

[0024] The regenerative cathode 13 is an electrode used for regenerating the oxide film on the common electrode 12. An insoluble electrode may be used as the regenerative cathode 13. More specifically, a platinum-iridium titanium electrode, a platinum electrode, a ruthenium titanium electrode, an iridium titanium oxide electrode, or a titanium electrode may be used as the regenerative cathode 13. As shown in Figure 1, if the regenerative cathode 13 is a plate-shaped electrode, it has two plate-shaped surfaces, for example, one surface is positioned to face the common electrode 12 and the other surface is positioned to face the inner wall surface of the electrolytic cell 10.

[0025] Although the shapes of the electrolytic anode 11, the common electrode 12, and the regenerative cathode 13 have been described as "plate-shaped," they are not limited to this. The shapes of the electrolytic anode 11, the common electrode 12, and the regenerative cathode 13 may be mesh-shaped, rod-shaped, or any other shape.

[0026] The electrolytic anode 11 and the shared electrode 12 used as the cathode are a pair of electrodes used for membrane-free electrolysis of the first aqueous solution L1. There is no membrane such as an ion exchange membrane between the electrolytic anode 11 and the shared electrode 12 used as the cathode. In other words, the electrolysis of the first aqueous solution L1 performed using the pair of electrolytic anodes 11 and the shared electrode 12 used as the cathode is membrane-free electrolysis. By performing membrane-free electrolysis of the first aqueous solution L1 using the pair of electrolytic anodes 11 and the shared electrode 12, hypochlorous acid gas used for air purification is generated.

[0027] The shared electrode 12 used as the anode and the regenerating cathode 13 are a pair of electrodes used for regenerating the oxide film covering the electrode material of the shared electrode 12. There is no diaphragm such as an ion exchange membrane between the shared electrode 12 used as the anode and the regenerating cathode 13. In other words, the electrolysis of the first aqueous solution L1 performed using the shared electrode 12 used as the anode and the regenerating cathode 13 is diaphragm-free electrolysis. The diaphragm-free electrolysis of the first aqueous solution performed using the pair of shared electrodes 12 used as the anode and the regenerating cathode 13 performs the regeneration treatment (regeneration treatment operation) of the oxide film covering the electrode material of the shared electrode 12.

[0028] The air supply unit 14 is a blower, for example, a fan, that introduces air from the external space R into the electrolytic cell 10. In this specification, "external space R" means the outside of the air purification device 1, that is, the outside of the housing C, for example, the indoor space.

[0029] The air blower pipe 15 is a tubular member that connects the air supply unit 14 and the electrolytic cell 10. One end of the air supply unit 14 is located on the side of the external space R, and the other end is connected to the air blower pipe 15 side. One end of the air blower pipe 15 is connected to the side of the air supply unit 14, and the other end is connected to the side of the electrolytic cell 10. The end of the air blower pipe 15 located on the side of the electrolytic cell 10 may be connected to the electrolytic cell 10 such that it is located below (negative side of the z axis) the liquid level S1 of the first aqueous solution L1 stored in the electrolytic cell 10.

[0030] The air supply unit 14 supplies air from the external space R to the first aqueous solution L1 stored in the electrolytic cell 10 via the air blower pipe 15. If the end of the air blower pipe 15 is positioned below the liquid level S1 of the first aqueous solution L1 stored in the electrolytic cell 10 (negative z-axis side), the air introduced into the first aqueous solution L1 via the air supply unit 14 and the air blower pipe 15 is released into the first aqueous solution L1 as bubbles B. A moisture-permeable waterproof membrane (not shown) may be placed at any position along the entire diameter of the air blower pipe 15. The moisture-permeable waterproof membrane allows air, which is a gas supplied from the external space R, and the moisture (water vapor) contained in that air to pass through, but does not allow the liquid first aqueous solution L1 to pass through. It is a membrane. The arrangement of this moisture-permeable waterproof membrane prevents the backflow of the first aqueous solution L1 from the electrolytic cell 10 to the air vent pipe 15.

[0031] The electrolytic cell-side internal space 16 is an upper space (space on the positive z-axis side) formed above the liquid surface S1 of the first aqueous solution L1 when the first aqueous solution L1 is stored in the electrolytic cell 10. In other words, the first aqueous solution L1 is not stored up to the upper interior surface of the electrolytic cell 10 (the xy-plane on the positive z-axis side), and the electrolytic cell 10 has the electrolytic cell-side internal space 16.

[0032] The water recovery unit 17 is a component that recovers moisture contained in the air that flows through the inside of the air purification device 1 and is released from the electrolytic cell 10 into the external space R as a liquid and returns it to the electrolytic cell 10. The water recovery unit 17 is, for example, a Peltier element that can cool and condense moisture contained in the air into water droplets. When the water recovery unit 17 is a Peltier element, the Peltier element has a heat dissipation surface and a heat absorption surface, and a cooling heat sink is provided on the heat absorption surface. The cooling heat sink can cool and condense moisture contained in the air passing through the cooling heat sink, turning it into water droplets.

[0033] The water recovery unit 17 may be positioned at the outlet 18 through which the air passes when it is released to the external space R, in order to recover moisture contained in the air circulating inside the air purification device 1. When the water recovery unit 17 is positioned at the outlet 18, moisture contained in the air that has circulated inside the air purification device 1 can be recovered efficiently. The water recovery unit 17 may also be positioned at any location in the internal space 16 on the electrolytic cell side.

[0034] The discharge port 18 is an opening for releasing mixed air M, which is a mixture of air flowing in from the air supply unit 14 and hypochlorous acid generated from the first aqueous solution L1 by membraneless electrolysis, into the external space R of the housing C. In Figure 1, as an example, the discharge port 18 is provided on the upper surface of the electrolytic cell 10 (the xy plane on the positive z-axis side), but it is sufficient that it is positioned above the liquid level S1 of the first aqueous solution L1. The shape of the discharge port 18 is cylindrical, for example, cylindrical or rectangular. If the upper surface of the electrolytic cell 10 (the surface on the positive z-axis side) is close to the ceiling surface of the housing C, the discharge port 18 may be a hole-like opening provided in a part of the upper surface of the electrolytic cell 10. Alternatively, the discharge port 18 and the upper surface of the housing C (the surface on the positive z-axis side) may be formed as a single integrated unit.

[0035] The discharge port 18 may be equipped with an openable / closable or removable cover (not shown). The cover may be kept closed when transporting, moving, or installing the air purification device 1, and may be opened or removed when using the air purification device 1.

[0036] The electrolytic cell 10 may further include a water level detection unit 19. The water level detection unit 19 detects the position of the liquid level S1 in the first aqueous solution L1. The water level detection unit 19 is, for example, a water level sensor. The water level detection unit 19 is positioned at least above (on the positive z-axis side of) the upper end (the portion on the positive z-axis side of) the electrolytic anode 11 and the common electrode 12.

[0037] If the air purification device 1 is equipped with a water level detection unit 19, the water recovery unit 17 recovers moisture from the mixed air M based on the position of the liquid level S1 detected by the water level detection unit 19 and supplies water to the electrolytic cell 10. More specifically, the water recovery unit 17 supplies water to the electrolytic cell 10 so as not to fall below the upper ends (the portion on the positive z-axis side) of the electrolytic anode 11 and the common electrode 12. Furthermore, the water recovery unit 17 supplies water to the electrolytic cell 10 so as not to fall below the upper end (the portion on the positive z-axis side) of the air blower pipe 15 connected to the electrolytic cell 10.

[0038] When the air purification device 1 is equipped with a water recovery unit 17 and a water level detection unit 19, the electrolytic anode 11 and the common electrode 12 can remain immersed in the first aqueous solution L1. Therefore, exposure of the electrolytic anode 11 and the common electrode 12 to air as the first aqueous solution L1 decreases can be suppressed, and the electrolytic efficiency of membrane-free electrolysis can be maintained. The supply tank 20 is also equipped with a water recovery unit and a water level detection unit similar to that of the electrolytic cell 10. It may be equipped with a section.

[0039] [Supply tank 20] The supply tank 20 is a tank for storing the second aqueous solution L2 containing chloride ions and for supplying the chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1. Figure 1 shows the state in which the second aqueous solution L2 is stored in the supply tank 20.

[0040] As the solute for the second aqueous solution L2, GHS (Globally Horticultural Standards) is used to ensure safety in case of leakage. Harmonized System of Classification and A substance with a safety level equivalent to that of sodium chloride (labelling of chemicals) is preferred. Specifically, the second aqueous solution L2 is an aqueous metal chloride solution containing metal ions and chloride ions. The second aqueous solution L2 is subjected to diaphragm electrolysis via an anion exchange membrane 30, described later, so that the metal ions contained in the second aqueous solution L2 react with hydroxide ions produced by the diaphragm electrolysis to form a precipitate of metal hydroxide. Preferably, the second aqueous solution L2 is a high-concentration magnesium chloride aqueous solution or a saturated magnesium chloride aqueous solution.

[0041] When a magnesium chloride aqueous solution is used as the second aqueous solution L2, the mass percentage concentration of the magnesium chloride aqueous solution is, for example, 1% to 35%. As an example, when the second aqueous solution L2 is a magnesium chloride aqueous solution, diaphragm electrolysis is performed, causing the magnesium ions contained in the magnesium chloride aqueous solution to react with the hydroxide ions produced by the diaphragm electrolysis to form a magnesium hydroxide precipitate. The "precipitate" of magnesium hydroxide includes hard, sandy, colloidal, slurry-like, or gel-like forms, and the aqueous solution may appear cloudy.

[0042] The supply tank 20 comprises a supply cathode 21, an internal space 22 on the supply tank side, and an outlet 23. The supply cathode 21 is an electrode used in diaphragm electrolysis via an anion exchange membrane 30, as a pair with the electrolytic anode 11. As shown in Figure 1, when the supply cathode 21 is a plate-shaped electrode, it has two plate-shaped surfaces, one of which is positioned to face the anion exchange membrane 30, and the other surface is positioned to face the internal wall surface of the supply tank 20. Although the case in which the supply cathode 21 has a plate shape has been described as an example, it is not limited to this. The shape of the supply cathode 21 may be any shape, such as plate-shaped, mesh-shaped, or rod-shaped, similar to the shapes of the electrolytic anode 11, the common electrode 12, and the regenerative cathode 13.

[0043] Through diaphragm electrolysis of the second aqueous solution L2 using a pair of supply cathodes 21 and electrolytic anodes 11, chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1. The chloride ions supplied to the first aqueous solution L1 are used for diaphragm-free electrolysis to produce hypochlorous acid.

[0044] An insoluble electrode may be used as the supply cathode 21. More specifically, for example, a titanium electrode, a platinum-iridium titanium electrode, a platinum electrode, a ruthenium titanium electrode, or an iridium titanium oxide electrode may be used.

[0045] The internal space 22 on the supply tank side is the upper space (space on the positive z-axis side) formed above the liquid surface S2 of the second aqueous solution L2 when the second aqueous solution L2 is stored in the supply tank 20. In other words, the second aqueous solution L2 is not stored up to the upper interior surface of the supply tank 20 (the xy plane on the positive z-axis side), and the supply tank 20 has the internal space 22 on the supply tank side.

[0046] The outlet 23 is an opening for discharging hydrogen gas, generated by the diaphragm electrolysis of the second aqueous solution L2, to the external space R of the housing C. The outlet 23 is, for example, a check valve. When a check valve is used as 23, the hydrogen gas inside the supply tank 20 is discharged to the external space R, but the inflow of gases such as air from the external space R can be suppressed. As the diaphragm electrolysis of the second aqueous solution L2 is repeated, hydrogen gas accumulates in the internal space 22 on the supply tank side, and the internal pressure of the supply tank 20 increases. This pressure causes the check valve at the outlet 23 to open, and the hydrogen gas is discharged to the external space R of the supply tank 20.

[0047] If the supply tank 20 does not have an outlet 23, an air passage (not shown) may be provided to connect the internal space 16 on the electrolytic cell side and the internal space 22 on the supply tank side. If an air passage is provided between the electrolytic cell 10 and the supply tank 20, the hydrogen gas may be discharged in the following order: internal space 22 on the supply tank side, air passage, internal space 16 on the electrolytic cell side, and outlet 18.

[0048] [Anion exchange membrane 30] The anion exchange membrane 30 is provided to connect the electrolytic cell 10 and the supply tank 20, and is a membrane-like member that allows anions to pass through based on the voltage applied between the electrolytic cell 10 and the supply tank 20. More specifically, when a voltage is applied between the electrolytic anode 11 and the supply cathode 21, diaphragm electrolysis is performed between the electrolytic cell 10 and the supply tank 20 via the anion exchange membrane 30. Through diaphragm electrolysis using the electrolytic anode 11 and the supply cathode 21, chloride ions contained in the second aqueous solution L2 permeate the anion exchange membrane 30 and are supplied to the first aqueous solution L1 (indicated by the negative x-axis direction and thick black arrow).

[0049] The anion exchange membrane 30 in this embodiment is not a type of anion exchange membrane that allows anions to permeate by osmosis without using electricity. Furthermore, magnesium ions, which are cations, do not permeate the anion exchange membrane 30. More specifically, when chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 by permeating the anion exchange membrane 30 through diaphragm electrolysis using the electrolytic anode 11 and the supply cathode 21, magnesium ions, which are cations, do not permeate the anion exchange membrane 30. The anion exchange membrane 30 is, for example, a hydrocarbon-based anion exchange membrane. Specific examples of hydrocarbon-based anion exchange membranes include membranes that have properties such as selective permeability of monovalent anions, alkali resistance, or high temperature resistance.

[0050] Furthermore, the chloride ion concentration of the second aqueous solution L2 may be approximately the same as that of the first aqueous solution L1, and a high-concentration chloride aqueous solution supply tank may be provided to supply a high-concentration chloride aqueous solution to the second aqueous solution L2.

[0051] [Current control unit 40] The current control unit 40 includes wiring 41, 42, 43, and 44. Wiring 41, 42, 43, and 44 are lines through which current flows. The electrolytic anode 11 is electrically connected to the current control unit 40 via wiring 41, the common electrode 12 via wiring 42, the regenerative cathode 13 via wiring 43, and the supply cathode 21 via wiring 44.

[0052] The current control unit 40 controls the currents used in non-diaphragm electrolysis, diaphragm electrolysis, and oxide film regeneration treatment. More specifically, it controls the first current used in non-diaphragm electrolysis, the second current used in diaphragm electrolysis, and the third current used in oxide film regeneration treatment. In other words, the current control unit 40 controls the chemical reactions that occur in non-diaphragm electrolysis and diaphragm electrolysis by controlling the first and second currents. The third current is the current that flows when a voltage is applied between the common electrode 12 and the regeneration cathode 13.

[0053] Let us now refer to Figure 2 and explain the configuration of the current control unit 40. Figure 2 is a functional block diagram of the current control unit 40 according to an embodiment. As shown in Figure 2, the current control unit 40 includes an input unit 40a, a storage unit 40b, a timing unit 40c, a processing unit 40d, and an output unit 40e.

[0054] The input unit 40a receives information from a voltage acquisition unit (voltmeter, etc.), water recovery unit 17, or water level detection unit 19, etc. (not shown), located outside the current control unit 40, regarding the voltage values ​​applied to the electrolytic anode 11, the common electrode 12, and the regenerative cathode 13, as well as information regarding the water level of the first aqueous solution L1 stored in the electrolytic cell 10. The voltage acquisition unit is, for example, a voltmeter, which acquires the voltage between the electrolytic anode 11 and the common electrode 12 used as the cathode. The input unit 40a outputs the received information to the processing unit 40d.

[0055] The memory unit 40b stores the relationship between the voltage value, conductivity, and chloride ion concentration, as well as the first and second correlations.

[0056] The relationships between voltage, conductivity, and chloride ion concentration are information regarding the relationship between voltage and the conductivity of the first aqueous solution L1, and information regarding the relationship between the conductivity of the first aqueous solution L1 and the chloride ion concentration of the first aqueous solution L1, which were experimentally evaluated and determined in advance.

[0057] The first correlation is information regarding the correlation between the operating time of the purification operation and the amount of decrease in the oxide film covering the shared electrode 12, which was experimentally evaluated and identified in advance.

[0058] The second correlation concerns the correlation between the operating time of the regeneration process and the increase in the oxide film formed by coating the electrode material of the shared electrode 12, which was experimentally evaluated and identified in advance.

[0059] The memory unit 40b outputs the relationship between the voltage value, conductivity, and chloride ion concentration stored in the memory unit 40b, the first correlation, and the second correlation to the processing unit 40d upon request from the processing unit 40d.

[0060] The storage unit 40b is composed of a non-volatile storage device. The non-volatile storage device is, for example, a flash memory or a hard disk drive. Note that the storage unit 40b may not be built into the current control unit 40, but may be provided as a separate unit.

[0061] The timing unit 40c outputs information regarding the operating time of the purification operation and information regarding the operating time of the regeneration operation to the processing unit 40d.

[0062] The processing unit 40d receives information from the input unit 40a, the storage unit 40b, and the timing unit 40c. Using the received information, the processing unit 40d identifies control information related to the non-diaphragm electrolysis, diaphragm electrolysis, and air supply by the air supply unit 14 performed in the purification operation, the switching from the purification operation (at least stopping the non-diaphragm electrolysis) to the regeneration operation, the reversal of the common electrode 12 from cathode to anode performed when the regeneration operation starts, the reversal of the common electrode 12 from anode to cathode performed when the regeneration operation stops, and the change in the current ratio of the first current and the second current. The processing unit 40d outputs the identified control information to the output unit 40e.

[0063] The output unit 40e receives control information from the processing unit 40d. The output unit 40e is electrically connected to the electrolytic anode 11, the common electrode 12, the regeneration cathode 13, and the supply cathode 21 via wirings 41 to 44, respectively. Similarly, the output unit 40e is electrically connected to the water recovery unit 17 and the water level detection unit 19 by wirings not shown. Based on the received control information, the output unit 40e controls the following: non-diaphragm electrolysis, diaphragm electrolysis and air supply by the air supply unit 14 performed in the purification operation; switching from the purification operation (at least stopping non-diaphragm electrolysis) to the regeneration operation; reversing the common electrode 12 from cathode to anode when the regeneration operation starts; reversing the common electrode 12 from anode to cathode when the regeneration operation stops; and the first current and It outputs control signals related to the change in the current ratio of the second current.

[0064] The electrolytic anode 11, the shared electrode 12, the regenerating cathode 13, the water recovery unit 17, and the water level detection unit 19, etc., receive control signals from the output unit 40e and execute control based on the received signals. For example, in the purification operation described later, when chloride ions are consumed by non-diaphragm electrolysis in the electrolytic cell 10 and the voltage of the first aqueous solution L1 rises, the voltage value information is input to the input unit 40a based on the voltage value acquired by the voltage acquisition unit, and control information regarding the change in the current ratio of the first current and the second current is identified in the processing unit 40d. The identified control information is, for example, to increase the current ratio of the second current used in diaphragm electrolysis. This control information is output by the output unit 40e to the electrolytic anode 11, the shared electrode 12, and the regenerating cathode 13, thereby increasing the amount of chloride ions contained in the second aqueous solution L2 supplied to the first aqueous solution L1.

[0065] The processing unit 40d receives information on the operating time of the purification operation from the timing unit 40c and also receives the first correlation stored in the storage unit 40b. When the operating time of the purification operation received from the timing unit 40c has elapsed a predetermined time, the processing unit 40d outputs a control signal to the output unit 40e to stop at least the non-diaphragm electrolysis, switch the common electrode 12 from cathode to anode, and start the regeneration process operation, among the non-diaphragm electrolysis, diaphragm electrolysis, and air supply by the air supply unit 14. The output unit 40e stops the non-diaphragm electrolysis by outputting the control signal to the electrolytic anode 11 and the common electrode 12 used as cathode. Following the cessation of non-diaphragm electrolysis, the output unit 40e outputs a control signal to the common electrode 12 to switch the common electrode 12 from cathode to anode, and outputs a control signal to start the regeneration process operation to the common electrode 12 used as anode and the regeneration cathode 13.

[0066] In other words, when a predetermined operating time for the purification operation has elapsed, the current control unit 40 (processing unit 40d) stops at least the non-diaphragm electrolysis and performs regeneration operation based on the first correlation relationship stored in the memory unit 40b, among non-diaphragm electrolysis, diaphragm electrolysis, and air supply by the air supply unit 14.

[0067] The processing unit 40d receives information on the operating time of the regeneration process from the timing unit 40c and also receives the second correlation stored in the storage unit 40b. When the operating time of the regeneration process received from the timing unit 40c has elapsed a predetermined time, the processing unit 40d stops the regeneration process, switches the common electrode 12 from cathode to anode, and outputs a control signal to the output unit 40e to restart diaphragm-free electrolysis. The output unit 40e outputs the control signal to the common electrode 12 used as the anode and the regeneration cathode 13, and also outputs a control signal to restart diaphragm-free electrolysis to the electrolytic anode 11 and the common electrode 12 used as the cathode.

[0068] In other words, the current control unit 40 performs a regeneration operation for a predetermined time based on the second correlation stored in the memory unit 40b, and then stops the regeneration operation. Then, it reverses the polarity of the common electrode 12 used as the anode, making it the common electrode 12 used as the cathode, and restarts diaphragm-free electrolysis.

[0069] Furthermore, it is also possible to stop all of the following: non-diaphragm electrolysis, diaphragm electrolysis, and air supply by the air supply unit 14, i.e., the purification operation, and perform the regeneration operation.

[0070] Next, we will return to Figure 1 and explain the details of the purification and regeneration operations.

[0071] [Purification operation] In the air purification device 1 according to this embodiment, air introduced from the external space R flows through the electrolytic cell 10 and is released back into the external space R along with hypochlorous acid in a purification operation. More specifically, The first aqueous solution L1 is electrolyzed without a diaphragm using the electrolytic anode 11 and the shared electrode 12 used as the cathode to produce hypochlorous acid, and air introduced from the external space R flows through the electrolytic cell 10 and is released back into the external space R along with the hypochlorous acid in a purification operation. The current control unit 40 controls the electrolysis without a diaphragm and the electrolysis with a diaphragm by flowing the first current and the second current.

[0072] In the membrane-free electrolysis of the first aqueous solution L1 stored in the electrolytic cell 10, which is carried out by the electrolytic anode 11 and the shared electrode 12 used as the cathode, the generation of hypochlorous acid and the reduction of chloric acid, which is generated as a byproduct, occur simultaneously.

[0073] First, let's explain the generation of hypochlorous acid (HClO). Through membrane-free electrolysis of the first aqueous solution L1, chlorine (Cl2) is generated at the electrolytic anode 11. The generated chlorine (Cl2) undergoes a hydrolysis reaction with the water in the first aqueous solution L1, producing hydrochloric acid (HCl) and hypochlorous acid (HClO). Hydrochloric acid (HCl) dissociates in aqueous solution, releasing hydrogen ions (H2). + ) and chloride ions (Cl - It exists as (H). Hydrochloric acid (HCl) dissociates in aqueous solution into hydrogen ions (H). + ) and chloride ions (Cl - It exists as a hydrogen ion (H). + ) is a hydroxide ion (OH) generated at the common electrode 12. - It reacts with ) to form water.

[0074] Next, we will explain the reduction of chloric acid (HClO3) generated as a byproduct. By diaphragm-free electrolysis of the first aqueous solution L1, not only hypochlorous acid but also chloric acid (HClO3) is generated as a byproduct. In this embodiment, since an electrode with chloric acid reducing properties is used as the common electrode 12 used as the cathode, the generated chloric acid can be reduced.

[0075] More specifically, we will first explain using a titanium electrode coated with an oxide film as an example of a common electrode 12 used as the cathode. In a titanium electrode coated with an oxide film, the reaction shown in Equation 1 below occurs, and the oxide film (titanium oxide) accepts electrons and reacts with hydrogen ions to produce TiOOH, reducing the titanium from tetravalent to trivalent. Furthermore, as shown in Equation 2 below, TiOOH and chlorate ions (ClO3) contained in the first aqueous solution L1 react with each other. -) By reacting with [substances not specified in the original], chloric acid is reduced to chloride ions, the surface of the titanium electrode is oxidized again, and an oxide film is formed. When the surface of the electrode material of the common electrode 12 is covered with the oxide film and the reducing ability is high, the generation of hypochlorous acid is stably carried out while the reaction proceeds in the direction of decreasing the chloric acid concentration. By suppressing the increase in the chloric acid concentration, the relative decrease in the chloride ion concentration contained in the first aqueous solution L1 can be suppressed, and the decrease in the production efficiency of hypochlorous acid in the vicinity of the electrolytic anode 11 can be suppressed. TiO2+H + +e - →TiOOH ···(Equation 1) 6TiOOH+ClO3 - →Cl - +6TiO2+3H2O ···(Equation 2)

[0076] The air flow path A indicated by the white arrow and the upward-right fine slanted-line arrow in FIG. 1 is a series of paths through which the air supplied from the external space R to the space purification device 1 flows through the electrolytic cell 10 and is discharged to the external space R as mixed air M containing hypochlorous acid. That is, the air flow path A shows the flow of air from the external space R, the air supply unit 14, the air duct 15, the first aqueous solution L1 stored in the electrolytic cell 10, the internal space 16 on the electrolytic cell side, the water recovery unit 17, the discharge port 18, to the external space R.

[0077] More specifically, in the air flow path A, as shown in FIG. 1, air is discharged as bubbles B from the external space R through the air supply unit 14 and the air duct 15 into the first aqueous solution L1 stored in the electrolytic cell 10. In other words, by bubbling the first aqueous solution L1 with the air introduced from the external space R, bubbles B are generated. The bubbles B are mixed with the hypochlorous acid generated by the diaphragm-free electrolysis of the first aqueous solution L1 to form the mixed air M. In FIG. 1, the bubbles B are shown as circles with upward-right thick slanted lines, and the mixed air M is shown as an arrow with upward-right fine slanted lines.

[0078] Here, the hypochlorous acid generated by the diaphragm-free electrolysis of the first aqueous solution L1 contains the first water The solution L1 contains both hypochlorous acid dissolved in it and hypochlorous acid gas that has volatilized and gasified into the internal space 16 on the electrolytic cell side. The hypochlorous acid dissolved in the first aqueous solution L1 is mixed with bubbles B and released as mixed air M from the outlet 18 via the water recovery unit 17 to the external space R. The hypochlorous acid gas that has volatilized and gasified into the internal space 16 on the electrolytic cell side is mixed with the mixed air M and released from the outlet 18 via the water recovery unit 17 to the external space R. The hypochlorous acid gas released into the external space R is supplied to the external space R. As the hypochlorous acid gas (mixed air M) flows through the water recovery unit 17, the water contained in the hypochlorous acid gas is recovered into the electrolytic cell 10. Along with the recovery of the water by the water recovery unit 17, the electrolyte components contained in the water are also recovered into the electrolytic cell 10. Therefore, hypochlorous acid gas with reduced electrolyte component content can be supplied to the external space R.

[0079] The electrolyte components include metal ions. More specifically, these metal ions are sodium ions, potassium ions, calcium ions, or magnesium ions. In other words, as hypochlorous acid gas (mixed air M) flows through the water recovery unit 17, the water contained in the hypochlorous acid gas is recovered into the electrolytic cell 10. Along with the recovery of this water by the water recovery unit 17, metal ions such as sodium ions contained in the water contained in the hypochlorous acid gas are also recovered into the electrolytic cell 10. Therefore, hypochlorous acid gas with reduced metal ion content can be supplied into the external space R.

[0080] By generating bubbles B in the first aqueous solution L1 through bubbling, the bubbles B float towards the liquid surface S1 due to buoyancy, and as they do so, hypochlorous acid and bubbles B come into gas-liquid contact, allowing the bubbles B to absorb hypochlorous acid. In other words, compared to gas-liquid contact between air and the liquid surface S1 of the first aqueous solution L1, the gas-liquid contact by generating bubbles B in the first aqueous solution L1 through bubbling allows bubbles B to absorb more hypochlorous acid and release it into the external space R as mixed air M. The mixed air M contains water evaporated from the first aqueous solution L1, but this water contained in the mixed air M is recovered by the water recovery unit 17 and returned to the first aqueous solution L1 as water droplets.

[0081] The mixed air M containing hypochlorous acid, released from the outlet 18 into the external space R of the air purification device 1, purifies the external space R. More specifically, the mixed air M containing hypochlorous acid also removes bacteria, fungi, viruses, or odors contained in the air of the external space R of the enclosure C.

[0082] In the purification operation, by performing diaphragm electrolysis, chloride ions contained in the second aqueous solution L2 stored in the supply tank 20 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by permeating the anion exchange membrane 30, in order to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by non-diaphragm electrolysis. Specifically, the current control unit 40 increases the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 by, for example, increasing the second current.

[0083] Furthermore, during the purification operation, the current control unit 40 controls the first current to replenish the chloride ions contained in the first aqueous solution L1 that have decreased due to membrane-free electrolysis, thereby supplying chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by permeating through the anion exchange membrane 30. The current control unit 40 flows the first current and the second current in a predetermined ratio so that the hypochlorous acid concentration of the first aqueous solution L1 is maintained at a predetermined concentration while replenishing the chloride ions that have decreased in the first aqueous solution L1.

[0084] Equation 3 below shows the equilibrium reaction equation for the hypochlorous acid generation reaction. Cl2+H2O⇔HCl+HClO...(Formula 3) Cl supplied from the second aqueous solution L2 to the first aqueous solution L1 - Depending on the increase or decrease, the equilibrium state is on the right. The concentration of hypochlorous acid in the first aqueous solution L1 stored in the electrolytic cell 10 is maintained at a predetermined concentration, that is, the Cl in the electrolytic cell 10 - The current control unit 40 controls the current so that it does not appear to increase or decrease.

[0085] [Regeneration operation] If the above purification operation is continued, the oxide film covering the electrode material of the shared electrode 12 used as the cathode may be reduced and decrease, potentially exposing a portion of the electrode material. The reduction in the oxide film covering the cathode may decrease the electrolysis efficiency and reduce the amount of hypochlorous acid produced. First, the details of the reduction of the oxide film covering the electrode material of the shared electrode 12 will be explained. The reduction of the oxide film covering the electrode material of the shared electrode 12 occurs due to the reduction of the oxide film. The reduction of the oxide film occurs when (1) hydrogen ions (H) contained in the first aqueous solution L1 are reduced by membraneless electrolysis. + Two types of reduction are possible: (1) reduction by (2) reduction by hydrogen (H2) generated by membrane-free electrolysis. Below, the reduction of the oxide film will be explained using a titanium electrode with an oxide film formed on the surface of the electrode material as an example.

[0086] (1) The oxide film contains hydrogen ions (H + ) when reduced by As shown in Equation 4 below, the oxide film (titanium dioxide) accepts electrons and reacts with hydrogen ions to produce TiOOH. Part of this is used to reduce chloric acid as explained using Equation 2 above, but the oxide film is further reduced by the reaction shown in Equation 5 below. As the purification operation continues and the reactions in Equations 4 and 5 below proceed, at least a portion of the electrode material of the titanium electrode is exposed. TiO2+H + +e - →TiOOH (Formula 4) TiOOH+3H + +3e - →Ti+2H2O...(Formula 5)

[0087] (2) When the oxide film is reduced by hydrogen (H2) Hydrogen (H2) is produced by membraneless electrolysis, and at the common electrode 12 used as the cathode, water (H2O) in the first aqueous solution L1 is converted into electrons (e -It is generated by receiving ). Some of the hydrogen (H2) is discharged as hydrogen gas from the outlet 18 along with hypochlorous acid, but the hydrogen other than the discharged hydrogen gas reduces the oxide film covering the electrode material of the shared electrode 12, as shown in equation 6 below. TiO2+2H2→Ti+2H2O (Formula 6)

[0088] Next, the relationship between the decrease in oxide film and the decrease in electrolysis efficiency will be explained. If the oxide film covering the electrode material of the shared electrode 12 decreases due to the reactions (1) and / or (2) above, the reduction rate of chloric acid generated as a byproduct of membraneless electrolysis decreases, and the chloric acid concentration increases. Chloride ions contained in the first aqueous solution L1 stored in the electrolytic cell 10 are used to generate chloric acid instead of hypochlorous acid, so the concentration of chloride ions contained in the first aqueous solution L1 decreases compared to when using the shared electrode 12 whose electrode material is covered with an oxide film. As the concentration of chloride ions contained in the first aqueous solution L1 decreases, the amount of chloride ions available for generating hypochlorous acid relatively decreases, which may reduce the generation efficiency (electrolysis efficiency) of hypochlorous acid near the electrolytic anode 11, and potentially decrease the concentration of hypochlorous acid produced. In other words, if the oxide film covering the electrode material of the shared electrode 12 decreases, the electrolysis efficiency may decrease, and the amount of hypochlorous acid produced may decrease.

[0089] Therefore, in the space purification device 1 according to this embodiment, if the oxide film covering the electrode material of the common electrode 12 used as the cathode decreases due to the purification operation, at least the diaphragm-free electrolysis is stopped and the device switches to a regeneration operation that performs oxide film regeneration. More specifically, based on the first correlation stored in the memory unit 40b of the current control unit 40, the current control unit 40 stops at least the diaphragm-free electrolysis and starts the regeneration operation. In the regeneration operation, the polarity of the common electrode 12 used as the cathode is reversed to make it the anode, and the anode is used A voltage is applied between the shared electrode 12 and the regenerating cathode 13, and a third current is passed through to regenerate the oxide film on the surface of the shared electrode 12. More specifically, by applying a voltage between the shared electrode 12 and the regenerating cathode 13, the oxide film covering the electrode material of the shared electrode 12 is reduced, a third current flows through the exposed portion of the electrode material, and an oxide film is formed.

[0090] When the shared electrode 12 is used as the anode, the reaction between titanium and the water constituting the first aqueous solution L1 proceeds from the state shown in equation 5 or equation 6 above, and the reaction shown in equation 7 below occurs, thereby regenerating the oxide film covering the electrode material (titanium electrode) of the shared electrode 12. Ti + 2H2O → TiO2 + 4H + +4e - ...(Formula 7)

[0091] Thus, during the regeneration operation, the oxide film covering the electrode material of the shared electrode 12 is regenerated. By regenerating the oxide film covering the electrode material of the shared electrode 12, the decrease in the reduction rate of chloric acid can be suppressed, and the increase in chloric acid concentration can be suppressed. By suppressing the increase in chloric acid concentration, the relative decrease in the concentration of chloride ions contained in the first aqueous solution L1 can be suppressed, and the decrease in the generation efficiency of hypochlorous acid near the electrolytic anode 11 can be suppressed. Therefore, the decrease in electrolysis efficiency due to the decrease in the oxide film covering the electrode material of the shared electrode 12 can be suppressed.

[0092] The current control unit 40 performs a regeneration operation for a predetermined time based on the second correlation stored in the memory unit 40b, and then stops the regeneration operation. Then, it reverses the polarity of the common electrode 12 used as the anode, making it the common electrode 12 used as the cathode, and restarts the membraneless electrolysis. In this way, the air purification device 1 according to this embodiment can stably generate a desired amount of hypochlorous acid gas through the purification operation and the regeneration operation.

[0093] As described above, the following effects can be enjoyed with the space purification device 1 according to the embodiment.

[0094] The space purification device 1 according to this embodiment includes an electrolytic cell 10 that stores a first aqueous solution L1 containing chloride ions and generates hypochlorous acid by non-diaphragm electrolysis of the first aqueous solution L1; a supply tank 20 that stores a second aqueous solution L2 containing chloride ions and supplies chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by diaphragm electrolysis; an electrolytic anode 11 provided in the electrolytic cell 10 and used for non-diaphragm electrolysis and diaphragm electrolysis; a reversible common electrode 12 composed of an electrode material and an oxide film covering the electrode material and used for non-diaphragm electrolysis and regeneration treatment of the oxide film; a regeneration cathode 13 used for regeneration treatment of the oxide film; a supply cathode 21 provided in the supply tank 20 and used for diaphragm electrolysis; and an anion exchange membrane 30 provided to connect the electrolytic cell 10 and the supply tank 20 and allows anions to pass through based on the voltage applied between the electrolytic anode 11 and the supply cathode 21. The first aqueous solution L1 is electrolyzed without a diaphragm using the electrolytic anode 11 and the common electrode 12 used as the cathode to produce hypochlorous acid, and a purification operation is performed in which air introduced from the outside space flows through the electrolytic cell 10 and is released into the outside space along with the hypochlorous acid. If the oxide film covering the electrode material of the common electrode 12 used as the cathode decreases as a result of this purification operation, the electrolysis without a diaphragm is stopped and the system is switched to a regeneration operation to regenerate the oxide film. In the regeneration operation, the polarity of the common electrode 12 used as the cathode is reversed to make it the anode, and a voltage is applied between the common electrode 12 used as the anode and the regeneration cathode 13 to regenerate the oxide film on the surface of the common electrode 12.

[0095] By having the above configuration, the oxide film covering the electrode material of the shared electrode 12 can be regenerated during the regeneration operation. By regenerating the oxide film covering the electrode material of the shared electrode 12, the decrease in the reduction rate of chloric acid can be suppressed, and the increase in chloric acid concentration can be suppressed. By suppressing the increase in chloric acid concentration, the relative decrease in the concentration of chloride ions contained in the first aqueous solution L1 can be suppressed, and the decrease in the generation efficiency of hypochlorous acid near the electrolytic anode 11 can be suppressed. Therefore, the shared This makes it possible to suppress the decrease in electrolysis efficiency that occurs due to the reduction of the oxide film covering the electrode material of electrode 12. Therefore, it is possible to provide a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas over a long period of time.

[0096] The air purification device 1 according to this embodiment includes a current control unit 40 that controls non-diaphragm electrolysis, diaphragm electrolysis, and oxide film regeneration processing. The current control unit 40 includes a storage unit 40b that stores a first correlation between the operating time of the purification operation and the amount of decrease in the oxide film covering the electrode material of the common electrode 12. When a predetermined operating time of the purification operation has elapsed, the current control unit 40b stops at least non-diaphragm electrolysis and performs regeneration processing based on the first correlation stored in the storage unit 40b.

[0097] With the above configuration, when a predetermined operating time for the purification operation has elapsed, in other words, when the oxide film covering the electrode material of the shared electrode 12 used as the cathode has decreased by a predetermined amount, at least the membrane-free electrolysis can be stopped and the regeneration operation can be started. Therefore, the decrease in the amount of hypochlorous acid produced by membrane-free electrolysis when the electrolysis efficiency is reduced can be suppressed. Thus, a space purification device 1 can be provided that can stably generate a desired amount of hypochlorous acid gas over a long period of time.

[0098] The storage unit 40b of the air purification device 1 according to this embodiment further stores a second correlation between the operating time of the regeneration process and the amount of increase in the oxide film formed by coating the electrode material of the common electrode 12. The current control unit 40 performs the regeneration process for a predetermined time based on the second correlation stored in the storage unit 40b, then stops the regeneration process, reverses the polarity of the common electrode 12 used as the anode to make it the common electrode 12 used as the cathode, and restarts diaphragm-free electrolysis.

[0099] By having the above configuration, a series of operations including stopping the purification operation (at least stopping the non-diaphragm electrolysis), starting and stopping the regeneration operation, and restarting the non-diaphragm electrolysis can be carried out smoothly and continuously.

[0100] In the purification operation performed by the air purification device 1 according to this embodiment, electrolysis with a diaphragm is performed to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by electrolysis without a diaphragm, and the chloride ions contained in the second aqueous solution L2 stored in the supply tank 20 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by passing through the anion exchange membrane 30.

[0101] With the above configuration, chloride ions contained in the second aqueous solution L2 stored in the supply tank 20 permeate the anion exchange membrane 30 and are supplied to the first aqueous solution L1 stored in the electrolytic cell 10. Therefore, a space purification device 1 can be provided that can stably generate a desired amount of hypochlorous acid gas over a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0102] In the purification operation performed by the air purification device 1 according to this embodiment, the device comprises a housing C that houses the electrolytic cell 10 and the supply tank 20, an air supply unit 14 that introduces air from the space outside the housing into the electrolytic cell 10, and an outlet 18 located in the electrolytic cell 10 that releases mixed air M, which is a mixture of air supplied from the air supply unit 14 and hypochlorous acid, into the outside space.

[0103] By providing the above configuration, gas-liquid contact is performed by generating bubbles B in the first aqueous solution L1 by bubbling. Compared to gas-liquid contact between air and the liquid surface S1 of the first aqueous solution L1, gas-liquid contact with bubbles B by bubbling allows more hypochlorous acid to be incorporated into the bubbles B and released into the external space R as mixed air M.

[0104] In the purification operation performed by the air purification device 1 according to this embodiment, the electrolytic cell 10 is equipped with a water recovery unit 17 capable of recovering moisture as a liquid from the mixed air M, and in the purification operation, the water recovery unit 17 The mixed air M containing hypochlorous acid from which moisture has been recovered is then released into the external space R.

[0105] With the above configuration, the mixed air M contains hypochlorous acid gas and water evaporated from the first aqueous solution L1. This water contained in the mixed air M is recovered by the water recovery unit 17 and returned to the first aqueous solution L1 as water droplets. Along with the recovery of water by the water recovery unit 17, the electrolyte components contained in the water can also be recovered into the electrolytic cell 10. Therefore, hypochlorous acid gas with reduced electrolyte content can be supplied to the external space R.

[0106] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention.

[0107] An overview of one aspect of this disclosure is as follows:

[0108] (Item 1) An electrolytic cell that stores a first aqueous solution containing chloride ions and produces hypochlorous acid by diaphragm-free electrolysis of the first aqueous solution, A supply tank for storing a second aqueous solution containing chloride ions and supplying the chloride ions contained in the second aqueous solution to the first aqueous solution by diaphragm electrolysis, Provided in the electrolytic cell, The electrolytic anode used in the aforementioned non-diaphragm electrolysis and the aforementioned diaphragm electrolysis, A reversible common electrode, composed of an electrode material and an oxide film covering the electrode material, used for the diaphragm-free electrolysis and the regeneration process of the oxide film, A regenerative cathode used in the regeneration process of the aforementioned oxide film, Provided in the aforementioned supply tank, A supply cathode used in the aforementioned diaphragm electrolysis, The electrolytic cell and the supply tank are provided to connect them. An anion exchange membrane that allows anions to pass through based on the voltage applied between the electrolytic anode and the supply cathode, Equipped with, The first aqueous solution is subjected to the non-diaphragm electrolysis using the electrolytic anode and the shared electrode used as the cathode to produce hypochlorous acid, and a purification operation is performed in which air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with the hypochlorous acid. If the oxide film covering the electrode material of the shared electrode used as the cathode decreases as a result of performing the purification operation, at least the diaphragm-free electrolysis is stopped and the operation is switched to a regeneration operation that regenerates the oxide film. In the regeneration process described above, the polarity of the shared electrode used as the cathode is reversed to make it the anode, and a voltage is applied between the shared electrode used as the anode and the regeneration cathode to regenerate the oxide film on the surface of the shared electrode. Air purification device. (Item 2) The system includes a current control unit that controls the aforementioned non-diaphragm electrolysis, the aforementioned diaphragm electrolysis, and the regeneration process of the oxide film, The current control unit, The system includes a storage unit that stores a first correlation between the operating time of the purification operation and the amount of decrease in the oxide film covering the electrode material of the shared electrode. When the predetermined operating time of the purification operation has elapsed, at least the diaphragm-free electrolysis is stopped based on the first correlation stored in the memory unit, and the regeneration operation is performed. The air purification device described in item 1. (Item 3) The memory unit further stores a second correlation between the operating time of the regeneration process and the amount of increase in the oxide film formed by covering the electrode material of the shared electrode. The current control unit performs the regeneration operation for a predetermined time based on the second correlation stored in the memory unit, then stops the regeneration operation, reverses the polarity of the shared electrode used as the anode so that it is used as the cathode, and restarts the diaphragmless electrolysis. The air purification device described in item 2. (Item 4) In the aforementioned purification operation, the diaphragm electrolysis is performed, and chloride ions contained in the second aqueous solution stored in the supply tank are supplied to the first aqueous solution stored in the electrolytic cell by passing them through the anion exchange membrane, in order to replenish the chloride ions contained in the first aqueous solution that have been reduced by the non-diaphragm electrolysis. A space purification device as described in any one of items 1 to 3. (Item 5) A housing for housing the electrolytic cell and the supply tank, An air supply unit that introduces air from the external space of the housing into the electrolytic cell, Distributed in the electrolytic cell, the discharge port releases the mixed air, which is a mixture of the air supplied from the air supply unit and the hypochlorous acid, to the external space. Equipped with, The air purification device described in item 1. (Item 6) The electrolytic cell includes a water recovery unit capable of recovering moisture as a liquid from the mixed air, In the purification operation, the mixed air containing the hypochlorous acid from which moisture has been recovered by the water recovery unit is released into the external space. A space purification device as described in item 1 or 5. [Explanation of symbols]

[0109] 1. Air purification device 10 Electrolytic cell 11 Anode for electrolysis 12 Common electrode 13 Regeneration cathode 14 Air supply unit 15 Air pipe 16 Internal space on electrolytic cell side 17 Water Recovery Section 18 Outlet 19 Water level detection unit 20 Supply tank 21 Supply cathode 22 Supply tank side internal space 23 Outlet 30 Anion exchange membrane 40 Current control unit 40a Input section 40b Storage section 40c timing section 40d Processing Unit 40e Output Section 41 Wiring 42 Wiring 43 Wiring 44 Wiring A Airflow channel B bubbles C cabinet L1 1st aqueous solution L2 2nd aqueous solution M mixed air R External space S1 liquid level S2 liquid level

Claims

1. An electrolytic cell that stores a first aqueous solution containing chloride ions and produces hypochlorous acid by diaphragm-free electrolysis of the first aqueous solution, A supply tank for storing a second aqueous solution containing chloride ions and supplying the chloride ions contained in the second aqueous solution to the first aqueous solution by diaphragm electrolysis, Provided in the electrolytic cell, The electrolytic anode used in the aforementioned non-diaphragm electrolysis and the aforementioned diaphragm electrolysis, A reversible common electrode, composed of an electrode material and an oxide film covering the electrode material, used for the diaphragm-free electrolysis and the regeneration process of the oxide film, A regenerative cathode used in the regeneration process of the aforementioned oxide film, Provided in the aforementioned supply tank, A supply cathode used in the aforementioned diaphragm electrolysis, The electrolytic cell and the supply tank are provided to connect them. An anion exchange membrane that allows anions to pass through based on the voltage applied between the electrolytic anode and the supply cathode, Equipped with, The first aqueous solution is subjected to the non-diaphragm electrolysis using the electrolytic anode and the shared electrode used as the cathode to produce hypochlorous acid, and a purification operation is performed in which air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with the hypochlorous acid. If the oxide film covering the electrode material of the shared electrode used as the cathode decreases as a result of performing the purification operation, at least the diaphragm-free electrolysis is stopped and the operation is switched to a regeneration operation that regenerates the oxide film. In the regeneration process described above, the polarity of the shared electrode used as the cathode is reversed to make it the anode, and a voltage is applied between the shared electrode used as the anode and the regeneration cathode to regenerate the oxide film on the surface of the shared electrode. Air purification device.

2. The system includes a current control unit that controls the aforementioned non-diaphragm electrolysis, the aforementioned diaphragm electrolysis, and the regeneration process of the oxide film, The current control unit, The system includes a storage unit that stores a first correlation between the operating time of the purification operation and the amount of decrease in the oxide film covering the electrode material of the shared electrode. When the predetermined operating time of the purification operation has elapsed, at least the diaphragm-free electrolysis is stopped based on the first correlation stored in the memory unit, and the regeneration operation is performed. The air purification device according to claim 1.

3. The memory unit further stores a second correlation between the operating time of the regeneration process and the amount of increase in the oxide film formed by covering the electrode material of the shared electrode. The current control unit performs the regeneration operation for a predetermined time based on the second correlation stored in the memory unit, then stops the regeneration operation, reverses the polarity of the shared electrode used as the anode so that it is used as the cathode, and restarts the diaphragmless electrolysis. The air purification device according to claim 2.

4. In the aforementioned purification operation, the diaphragm electrolysis is performed, and chloride ions contained in the second aqueous solution stored in the supply tank are supplied to the first aqueous solution stored in the electrolytic cell by passing them through the anion exchange membrane, in order to replenish the chloride ions contained in the first aqueous solution that have been reduced by the non-diaphragm electrolysis. A space purification device according to any one of claims 1 to 3.

5. A housing for housing the electrolytic cell and the supply tank, An air supply unit that introduces air from the external space of the housing into the electrolytic cell, Distributed in the electrolytic cell, the discharge port releases the mixed air, which is a mixture of the air supplied from the air supply unit and the hypochlorous acid, to the external space. Equipped with, The air purification device according to claim 1.

6. The electrolytic cell includes a water recovery unit capable of recovering moisture as a liquid from the mixed air, In the purification operation, the mixed air containing the hypochlorous acid from which moisture has been recovered by the water recovery unit is released into the external space. The air purification device according to claim 1 or 5.

Images