Electrolyzed water generator, air purification device

Abstract

This technology provides a way to suppress the collision of water flow with the membrane surface of an anion exchange membrane. [Solution] The electrolytic cell 30 stores a first aqueous solution L1 containing chloride ions, and the supply tank 40 stores a second aqueous solution L2 containing chloride ions. The anion exchange membrane 50 is provided to connect the electrolytic cell 30 and the supply tank 40 and is permeable to anions containing chloride ions. The protective membrane 70 is provided on the electrolytic cell 30 side of the anion exchange membrane 50. The electrolytic cell 30 generates hypochlorous acid by non-diaphragm electrolysis of the first aqueous solution L1, and the supply tank 40 supplies chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by diaphragm electrolysis, allowing them to pass through the anion exchange membrane 50 and the protective membrane 70. The protective membrane 70 includes a porous membrane 72 having a mesh-like network of micropores.

Description

[Technical Field]

[0001] The present disclosure relates to an electrolyzed water generating device and a space purification device. [Background Art]

[0002] Electrolyzed water containing hypochlorous acid is produced using an electrolytic cell in which an anion exchange membrane is used as a diaphragm and an anode and the diaphragm are arranged in proximity to each other. In order to suppress deterioration of the anion exchange membrane caused by chlorine gas generated on the anode surface, a protective membrane having a plurality of slit-shaped cuts is arranged between the anode and the anion exchange membrane (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-322053 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Hypochlorous acid is generated when chlorine gas reacts with water. Further, electrolysis can generate a water flow toward the membrane surface of the anion exchange membrane. Even when a protective membrane having a plurality of slit-shaped cuts is used for the anion exchange membrane, it is difficult to suppress the impact of the water flow on the membrane surface of the anion exchange membrane.

[0005] The present disclosure has been made in view of the above problem, and provides a technique for suppressing the impact of water flow on the membrane surface of an anion exchange membrane. [Means for Solving the Problem]

[0006] To solve the above problems, an electrolytic water generator according to one embodiment of the present disclosure comprises an electrolytic cell for storing a first aqueous solution containing chloride ions, a supply tank for storing a second aqueous solution containing chloride ions, an anion exchange membrane provided to connect the electrolytic cell and the supply tank and permeable to anions containing chloride ions, and a protective membrane provided on the electrolytic cell side of the anion exchange membrane. The electrolytic cell generates hypochlorous acid by non-diaphragm electrolysis of the first aqueous solution, and the supply tank supplies chloride ions contained in the second aqueous solution to the first aqueous solution by diaphragm electrolysis, allowing them to pass through the anion exchange membrane and the protective membrane, and the protective membrane includes a porous membrane having a mesh-like structure of micropores.

[0007] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, recording media, or computer programs, are also valid forms of this disclosure. [Effects of the Invention]

[0008] This disclosure makes it possible to suppress the collision of water flow with the membrane surface of an anion exchange membrane. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a front cross-sectional view showing the air purification device according to Example 1. [Figure 2] Figure 2 is a magnified view of the anion exchange membrane and porous membrane shown in Figure 1. [Figure 3] Figure 3 shows the change in the concentration of hypochlorous acid over time in the air purification device shown in Figure 1. [Figure 4] Figure 4 is a front cross-sectional view showing the air purification device according to Example 2. [Figure 5] Figure 5 is a magnified view of the anion exchange membrane, porous membrane, and water-permeable membrane shown in Figure 4. [Modes for carrying out the invention]

[0010] The following describes specific embodiments of this disclosure in detail with reference to the drawings. The x, y, and z coordinates shown in the figures are for convenience in explaining the positional relationships of the components. Unless otherwise specified, the positive z-axis direction is vertically upward. Also, the x and y planes are horizontal planes and are consistent across the drawings.

[0011] (Example 1) Figure 1 is a front cross-sectional view showing the air purification device 20. The air purification device 20 performs membrane-free electrolysis of a first aqueous solution L1 containing chloride ions in an electrolytic cell 30, which will be described later, to generate and volatilize hypochlorous acid. The air purification device 1 releases the generated hypochlorous acid into the external space R of the housing C that constitutes the air purification device 20, thereby removing bacteria, fungi, viruses, or odors contained in the air in the external space R of the air purification device 20. In addition, membrane-assisted electrolysis is performed to supply chloride ions contained in the second aqueous solution L2 stored in the supply tank 40 to the first aqueous solution L1 stored in the electrolytic cell 30 by permeating through the anion exchange membrane 50 and the protective membrane 70, in order to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by membrane-free electrolysis.

[0012] The air purification device 20 is installed indoors. Preferably, the installation location of the air purification device 20 is a place where airflow can occur. More specifically, the installation location of the air purification device 20 is indoors. Specific examples of installation locations for the air purification device 20 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.

[0013] In this specification, "external space R" means the area outside the air purification device 20, that is, the area outside the housing C, for example, the indoor space. If the air purification device 20 is located inside equipment such as the air conditioner mentioned above, the area outside the housing C and the area inside the equipment are also included in "external space R".

[0014] As shown in Figure 1, the air purification device 20 comprises a housing C, an electrolytic cell 30, and a current control unit 60. The air purification device 20 may further include a supply tank 40, an anion exchange membrane 50, and a protective membrane 70. The supply tank 40 and the anion exchange membrane 50 are used to supply chloride ions from the supply tank 40 to the electrolytic cell 30 in order to continue the purification operation of the external space R without supplying chloride ions to the electrolytic cell 30 from the outside for a long period of time. Furthermore, the protective membrane 70 is used to protect the anion exchange membrane 50.

[0015] The housing C is a box-shaped member that houses the electrolytic cell 30, the supply tank 40, the anion exchange membrane 50, the current control unit 60, and the protective membrane 70. In other words, the air purification device 20 is a unit integrated by the housing C. The air purification device 20 is small in size, and if the shape of the housing C is a rectangular parallelepiped, it is for example about 10 cm × 7 cm × 4 cm.

[0016] The electrolytic cell 30 is a tank for storing a first aqueous solution L1 containing chloride ions and for producing hypochlorous acid by non-diaphragm electrolysis of the first aqueous solution L1. The supply tank 40 is a tank for storing a second aqueous solution L2 containing chloride ions and for supplying chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by permeating through an anion exchange membrane 50 and a protective membrane 70 by diaphragm electrolysis. The protective membrane 70 will be described later, so it will be omitted in the following description. More specifically, chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 by diaphragm electrolysis via an anion exchange membrane 50 provided to connect the electrolytic cell 30 and the supply tank 40. The anion exchange membrane 50 is permeable to anions, including chloride ions. The current control unit 60 controls non-diaphragm electrolysis and diaphragm electrolysis.

[0017] When assuming continuous use of 8 hours a day every day for one year, it is preferable that the volume of the supply tank 40 is about 12 times or more the volume of the electrolytic cell 30, for example. With such a volume ratio, the supply tank 40 can store the second aqueous solution L2 containing a sufficient amount of chloride ions that needs to be supplied to the first aqueous solution L1 in the electrolytic cell 30. Therefore, chloride ions can be stably supplied from the second aqueous solution L2 stored in the supply tank 40 to the first aqueous solution L1 stored in the electrolytic cell 30.

[0018] The electrolytic cell 30 and the supply tank 40 are arranged in the order of the electrolytic cell 30 and the supply tank 40 sequentially from the negative x-axis side in a front view. An anion exchange membrane 50 is arranged between the electrolytic cell 30 and the supply tank 40 so as to connect the electrolytic cell 30 and the supply tank 40. For example, when the opposing surfaces of the electrolytic cell 30 and the supply tank 40 are formed of frame-shaped members, the anion exchange membrane 50 may be arranged so as to be fitted into the frame-shaped members. The current control unit 60 is arranged at any position inside the housing C, but is not limited thereto, and may be arranged outside the housing C and connected via wireless communication or the like.

[0019] [Electrolytic cell 30] The electrolytic cell 30 is a tank for storing the first aqueous solution L1 containing chloride ions and generating hypochlorous acid by subjecting the first aqueous solution L1 to non-diaphragm electrolysis. The electrolytic cell 30 has, for example, a box shape, but any shape capable of storing the first aqueous solution L1 is acceptable. FIG. 1 shows a state where the first aqueous solution L1 is stored in the electrolytic cell 30. The volume of the first aqueous solution L1 stored in the electrolytic cell 30 is, for example, about 2 mL to 10 mL. The first aqueous solution L1 is, for example, an aqueous solution in which a conductive electrolyte is dissolved, that is, an electrolytic solution, and specifically is 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.

[0020] 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 said numerical range or numerical value, it is possible to generate hypochlorous acid necessary for purifying the external space R while simultaneously suppressing the generation of chlorine that may be generated.

[0021] The electrolytic cell 30 includes an electrolytic cell-side anode 31, an electrolytic cell-side cathode 32, an air supply unit 33, a blower pipe 34, an electrolytic cell-side internal space 35, a water recovery unit 36, and a discharge port 37. The electrolytic cell 30 may further include a water level detection unit 38.

[0022] The electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 are a pair of electrodes used for the electrolysis of the first aqueous solution L1. Insoluble electrodes may be used as the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32. More specifically, for example, platinum-iridium titanium electrodes, platinum electrodes, ruthenium titanium electrodes, or iridium titanium oxide electrodes may be used. Alternatively, the electrolytic cell-side cathode 32 may be a titanium electrode, iron electrode, tin electrode, nickel electrode, or an alloy of the aforementioned metals, each having an oxide film formed on its surface. An example of a case where the electrolytic cell-side cathode 32 is a metal alloy is 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. The shape of the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 may be plate-shaped, mesh-shaped, or rod-shaped.

[0023] There is no diaphragm, such as an ion exchange membrane, between the electrolytic cell anode 31 and the electrolytic cell cathode 32. In other words, the electrolysis of the first aqueous solution L1 performed using the pair of electrolytic cell anodes 31 and cathode 32 is diaphragm-free electrolysis. Hypochlorous acid gas, which is used for purifying the external space R, is generated by the diaphragm-free electrolysis of the first aqueous solution L1 performed using the pair of electrolytic cell anodes 31 and cathode 32.

[0024] The air supply unit 33 is a blower, for example, a blower, that introduces air from the external space R into the electrolytic cell 30.

[0025] The air blower pipe 34 is a tubular member that connects the air supply unit 33 and the electrolytic cell 30. One end of the air supply unit 33 is located on the side of the external space R, and the other end is connected to the air blower pipe 34 side. One end of the air blower pipe 34 is connected to the side of the air supply unit 33, and the other end is connected to the side of the electrolytic cell 30. The end of the air blower pipe 34 located on the side of the electrolytic cell 30 is connected to the electrolytic cell 30 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 30.

[0026] The air supply unit 33 supplies air from the external space R to the first aqueous solution L1 stored in the electrolytic cell 30 via the blower pipe 34. When the end of the blower pipe 34 is positioned below the liquid level S1 of the first aqueous solution L1 stored in the electrolytic cell 30 (negative z-axis side), the air introduced into the first aqueous solution L1 via the air supply unit 33 and the blower pipe 34 is released into the first aqueous solution L1 as bubbles B. A moisture-permeable waterproof membrane (not shown) may be placed over the entire diameter of the blower pipe 34. The moisture-permeable waterproof membrane is a membrane that 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 first aqueous solution L1, which is a liquid, to pass through. The placement of this moisture-permeable waterproof membrane prevents backflow of the first aqueous solution L1 from the electrolytic cell 30 to the blower pipe 34.

[0027] The electrolytic cell-side internal space 35 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 30. In other words, the first aqueous solution L1 is not stored up to the upper interior surface of the electrolytic cell 30 (the xy-plane on the positive z-axis side), and the electrolytic cell 30 has the electrolytic cell-side internal space 35.

[0028] The water recovery unit 36 ​​is a component that recovers moisture contained in the air that flows through the inside of the air purification device 20 and is released from the electrolytic cell 30 into the external space R as a liquid and returns it to the electrolytic cell 30. The water recovery unit 36 ​​is, for example, a Peltier element that can cool and condense moisture contained in the air into water droplets. When the water recovery unit 36 ​​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.

[0029] The water recovery unit 36 ​​may be located at the discharge port 37 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 20. When the water recovery unit 36 ​​is located at the discharge port 37, moisture contained in the air that has circulated inside the air purification device 20 can be recovered efficiently. The water recovery unit 36 ​​may be located at any position in the internal space 35 on the electrolytic cell side.

[0030] The discharge port 37 is an opening for releasing mixed air M, which is a mixture of air flowing in from the air supply unit 33 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 37 is provided on the upper surface of the electrolytic cell 30 (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 37 is cylindrical, including, for example, cylindrical or rectangular tubes. If the upper surface of the electrolytic cell 30 (the surface on the positive z-axis side) is close to the ceiling surface of the housing C, the discharge port 37 may be a hole-like opening provided in a part of the upper surface of the electrolytic cell 30. Alternatively, the discharge port 37 and the upper surface of the housing C (the surface on the positive z-axis side) may be formed as a single integrated unit.

[0031] The discharge port 37 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 20, and may be opened or removed when using the air purification device 20.

[0032] Next, we will explain the sequence of operations (purification operation) for supplying the hypochlorous acid gas generated by the air purification device 20 to the external space R. In the air purification device 20 according to this embodiment, air introduced from the external space R flows through the electrolytic cell 30 and is supplied to the external space R together with hypochlorous acid.

[0033] The airflow path A, indicated by the white arrow and the upward-sloping arrow in Figure 1, is a series of paths through which air supplied from the external space R to the air purification device 20 flows through the electrolytic cell 30 and is released back to the external space R as mixed air M containing hypochlorous acid. In other words, airflow path A shows the flow of air from the external space R, the air supply unit 33, the blower pipe 34, the first aqueous solution L1 stored in the electrolytic cell 30, the internal space on the electrolytic cell side 35, the water recovery unit 36, the discharge port 37, and back to the external space R.

[0034] More specifically, in airflow channel A, as shown in Figure 1, air supplied to the electrolytic cell 30 from the external space R via the air supply unit 33 and the air blower 34 is released as bubbles B into the first aqueous solution L1 stored in the electrolytic cell 30. In other words, bubbles B are generated by bubbling the first aqueous solution L1 with air introduced from the external space R. The released bubbles B are mixed with hypochlorous acid generated by the membraneless electrolysis of the first aqueous solution L1 to form mixed air M.

[0035] Here, the hypochlorous acid produced by the non-diaphragm electrolysis of the first aqueous solution L1 includes both hypochlorous acid dissolved in the first aqueous solution L1 and hypochlorous acid gas that has volatilized and gasified into the internal space 35 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 37 through the water recovery unit 36 ​​to the external space R. The hypochlorous acid gas that has volatilized and gasified into the internal space 35 on the electrolytic cell side is mixed with bubbles B which are mixed with hypochlorous acid and released as mixed air M from the outlet 37 through the water recovery unit 36 ​​to the external space R.

[0036] When the air purification device 20 is equipped with a water recovery unit 36, the hypochlorous acid gas (mixed air M) flows through the water recovery unit 36, and the water contained in the hypochlorous acid gas is recovered into the electrolytic cell 30. Along with the recovery of this water by the water recovery unit 36, metal ions such as sodium ions contained in the water contained in the hypochlorous acid gas are also recovered into the electrolytic cell 30. Therefore, hypochlorous acid gas with reduced water content and lower metal ion content can be supplied to the external space R. Metal ion components are included in the electrolyte components. More specifically, metal ions are sodium ions, potassium ions, calcium ions, or magnesium ions.

[0037] 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 36 ​​and returned to the first aqueous solution L1 as water droplets.

[0038] The mixed air M containing hypochlorous acid, released from the outlet 37 into the external space R of the air purification device 20, 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.

[0039] The electrolytic cell 30 may further include a water level detection unit 38. The water level detection unit 38 detects the position of the liquid level S1 in the first aqueous solution L1. The water level detection unit 38 is, for example, a water level sensor. The water level detection unit 38 is positioned at least above (on the positive z-axis side of) the upper ends (the portions on the positive z-axis side of) the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32.

[0040] If the air purification device 20 is equipped with a water level detection unit 38, the water recovery unit 36 ​​recovers moisture from the mixed air M based on the position of the liquid level S1 detected by the water level detection unit 38 and supplies water to the electrolytic cell 30. More specifically, the water recovery unit 36 ​​supplies water to the electrolytic cell 30 so as not to fall below the upper ends (the portion on the positive z-axis) of the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32. Furthermore, the water recovery unit 36 ​​supplies water to the electrolytic cell 30 so as not to fall below the upper end (the portion on the positive z-axis) of the air blower pipe 34 connected to the electrolytic cell 30.

[0041] If the air purification device 20 is equipped with a water recovery unit 36 ​​and a water level detection unit 38, the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 can remain immersed in the first aqueous solution L1. Therefore, exposure of the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 to the 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 40 may also be equipped with a water recovery unit and a water level detection unit similar to those of the electrolytic cell 30.

[0042] The supply tank 40 and anion exchange membrane 50, which will be described next, are used to supply chloride ions from the supply tank 40 to the electrolytic cell 30 in order to continue the purification operation without supplying chloride ions from the outside to the electrolytic cell 30 for a long period of time, and to continue the purification of the external space R.

[0043] [Supply tank 40] The supply tank 40 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 40.

[0044] As the solute for the second aqueous solution L2, it is preferable to use a substance whose GHS (Globally Harmonized System of Classification and Labelling of Chemicals) classification is as safe as that of sodium chloride, in order to ensure safety in the event of leakage. 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 50, which will be described later. This reaction between the metal ions contained in the second aqueous solution L2 and the hydroxide ions generated by the diaphragm electrolysis forms 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.

[0045] 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.

[0046] The supply tank 40 comprises a supply tank-side cathode 41, a supply tank-side internal space 42, and an outlet 43. The supply tank-side cathode 41 is an electrode used in diaphragm electrolysis via an anion exchange membrane 50, as a pair with the electrolytic cell-side anode 31. Chloride ions are supplied from the second aqueous solution L2 to the first aqueous solution L1 by diaphragm electrolysis of the second aqueous solution L2, which is performed using the pair of supply tank-side cathodes 41 and the electrolytic cell-side anode 31.

[0047] An insoluble electrode may be used as the supply tank side cathode 41. 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. The shape of the supply tank side cathode 41 may be any of the following, such as a plate, mesh, or rod, similar to the shapes of the electrolytic cell side anode 31 and the electrolytic cell side cathode 32.

[0048] The internal space 42 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 40. In other words, the second aqueous solution L2 is not stored up to the upper interior surface of the supply tank 40 (the xy-plane on the positive z-axis side), and the supply tank 40 has the internal space 42 on the supply tank side.

[0049] The outlet 43 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 43 is, for example, a check valve. When a check valve is used as the outlet 43, the hydrogen gas inside the supply tank 40 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 42 on the supply tank side, and the internal pressure of the supply tank 40 increases. This pressure causes the check valve of the outlet 43 to open, and the hydrogen gas is discharged to the external space R of the supply tank 40.

[0050] If the supply tank 40 does not have an outlet 43, an air passage (not shown) may be provided to connect the internal space 35 on the electrolytic cell side and the internal space 42 on the supply tank side. If an air passage is provided between the electrolytic cell 30 and the supply tank 40, the hydrogen gas may be discharged in the following order: internal space 42 on the supply tank side, air passage, internal space 35 on the electrolytic cell side, and outlet 37.

[0051] The anion exchange membrane 50 is provided to connect the electrolytic cell 30 and the supply tank 40, and is a membrane-like member that allows anions to pass through based on the voltage applied between the electrolytic cell 30 and the supply tank 40. More specifically, when a voltage is applied between the anode 31 on the electrolytic cell side and the cathode 41 on the supply tank side, diaphragm electrolysis is performed through the anion exchange membrane 50. Through diaphragm electrolysis using the anode 31 on the electrolytic cell side and the cathode 41 on the supply tank side, chloride ions contained in the second aqueous solution L2 permeate the anion exchange membrane 50 and are supplied to the first aqueous solution L1 (indicated by the negative x-axis direction and thick black arrow).

[0052] The anion exchange membrane 50 in this embodiment is not a type of anion exchange membrane that allows anions to permeate by osmosis without the use of electricity. Furthermore, magnesium ions, which are cations, do not permeate the anion exchange membrane 50. More specifically, when chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 by diaphragm electrolysis using the electrolytic cell side anode 31 and the supply tank side cathode 41, magnesium ions, which are cations, do not permeate the anion exchange membrane 50. The anion exchange membrane 50 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.

[0053] The anion exchange membrane 50 is positioned between the electrolytic cell 30 and the supply tank 40. If the surfaces of the electrolytic cell 30 and the supply tank 40 facing each other are formed by a frame-shaped member, the anion exchange membrane 50 may be positioned so as to be fitted into the frame-shaped member. In other words, the electrolytic cell 30 and the supply tank 40 are connected via the anion exchange membrane 50 in a way that allows anions to pass through.

[0054] 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.

[0055] The current control unit 60 includes wiring 61, 62, and 63. Wiring 61, 62, and 63 are lines through which current flows. The electrolytic cell-side anode 31 is electrically connected to the current control unit 60 via wiring 61, the electrolytic cell-side cathode 32 via wiring 62, and the supply tank-side cathode 41 via wiring 63.

[0056] The current control unit 60 controls the currents used in non-diaphragm electrolysis and diaphragm electrolysis. More specifically, it controls the first current used in non-diaphragm electrolysis and the second current used in diaphragm electrolysis. In other words, the current control unit 60 controls the chemical reactions that occur in non-diaphragm electrolysis and diaphragm electrolysis by controlling the first current and the second current.

[0057] In the purification operation, diaphragm electrolysis is performed to supply chloride ions contained in the second aqueous solution L2 stored in the supply tank 40 to the first aqueous solution L1 stored in the electrolytic cell 30 by permeating the anion exchange membrane 50, 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 60 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.

[0058] Furthermore, during the purification operation, the current control unit 60 controls the first current to replenish the chloride ions contained in the first aqueous solution L1 that have decreased due to membraneless electrolysis, thereby supplying chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by permeating the anion exchange membrane 50. The current control unit 60 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 or within a predetermined range, while replenishing the chloride ions that have decreased in the first aqueous solution L1. The predetermined concentration is, for example, the Cl concentration in the electrolytic cell 30. - This is the concentration at which the apparent increase or decrease does not occur. In other words, the predetermined concentration is, for example, the amount of Cl stored in the first aqueous solution L1. - This is the concentration at which the initial concentration of the substance does not appear to change. The Cl stored in the first aqueous solution L1 -The specified concentration range is a Cl concentration sufficient to stably supply hypochlorous acid gas from the electrolytic cell 30. - This is the range of concentrations.

[0059] The following reaction equation 1 shows the equilibrium reaction equation for the hypochlorous acid generation reaction. Cl2 + H2O ⇔ HCl + HClO ... (Reaction Equation 1) Cl supplied from the second aqueous solution L2 to the first aqueous solution L1 - Depending on the increase or decrease of , the equilibrium state may shift to the right or to the left. The concentration of hypochlorous acid in the first aqueous solution L1 stored in the electrolytic cell 30 is maintained at a predetermined concentration, that is, the Cl in the electrolytic cell 30 - The current control unit 60 controls the current so that it does not appear to increase or decrease.

[0060] [Protective film 70] When the water flow generated by electrolysis collides with the anion exchange membrane 50, the anion exchange membrane 50 deteriorates. To suppress the deterioration of the anion exchange membrane 50, it is desirable to suppress the collision of water flow with the anion exchange membrane 50. For this purpose, a protective membrane 70 is provided on the electrolytic cell 30 side of the anion exchange membrane 50 in the air purification device 20. That is, the anion exchange membrane 50 and the protective membrane 70 are arranged adjacent to each other, and the anion exchange membrane 50 located on the electrolytic cell 30 side is covered by the protective membrane 70. In particular, the protective membrane 70 consists of only one layer of porous membrane 72.

[0061] Figure 2 is a partially enlarged view of the anion exchange membrane 50 and the porous membrane 72. The porous membrane 72 is a semipermeable membrane having a network of micropores 74. It has liquid retention properties due to the surface tension generated on its fine porous surface, but it has low water permeability and does not actively allow water to pass through. Therefore, the porous membrane 72 can suppress collisions of ions or water particles with the anion exchange membrane 50.

[0062] The porous membrane 72 is one of the following: a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, or a nanofiltration (NF) membrane. If the porous membrane 72 is a microfiltration membrane, the diameter of the micropores 74 is, for example, 100 nm to 10000 nm. If the porous membrane 72 is an ultrafiltration membrane, the diameter of the micropores 74 is, for example, 10 nm to 1000 nm. If the porous membrane 72 is a nanofiltration membrane, the diameter of the micropores 74 is, for example, 1 nm to 100 nm. The material constituting the porous membrane 72 is, for example, PET (Poly Ethylene Terephthalate), PTFE (PolyTetraFluoroEthylene), PVDF (PolyVinylidene DiFluoride), etc. Furthermore, the shape of the mesh-like micropores 74 may be symmetrical (lattice-like, etc.) or asymmetrical. The surface of the porous membrane 72 may be treated to make it hydrophilic in order to further improve the conductivity between the electrolytic cell 30 and the supply tank 40.

[0063] When membrane-free electrolysis is performed in the electrolytic cell 30, hypochlorite ions are attracted to the anode 31 on the electrolytic cell side and do not actively move toward the porous membrane 72 and the anion exchange membrane 50. Therefore, there is almost no contact between the hypochlorite ions and the anion exchange membrane 50. In addition, since the porous membrane 72 has liquid-holding capacity due to the micropores 74, contact between hypochlorite ions moved by the water flow and the anion exchange membrane 50, as well as the physical load on the anion exchange membrane 50 by the water flow, is reduced. Here, the water flow is either convection generated during membrane-free electrolysis or bubbles B generated from the air supply unit 33.

[0064] On the other hand, if membrane-free electrolysis is not performed in the electrolytic cell 30, hypochlorite ions move to the anion exchange membrane 50 side by natural diffusion. Figure 3 shows the change in hypochlorous acid concentration in the air purification device 20 over time. The horizontal axis shows the elapsed time since membrane-free electrolysis was stopped, and the vertical axis shows the hypochlorous acid concentration. In the graph of Figure 2, the hypochlorous acid concentration in the electrolytic cell 30 is shown as "hypochlorous acid concentration 80". When membrane-free electrolysis is stopped, hypochlorite ions naturally diffuse while volatilizing, self-decomposing, etc., so the hypochlorous acid concentration 80 in the electrolytic cell 30 decreases over time. In addition, the liquid retention capacity of the porous membrane 72 makes it difficult for hypochlorite ions to pass through the porous membrane 72.

[0065] In the graph in Figure 2, the concentration of hypochlorous acid on the surface of the anion exchange membrane 50 is shown as "hypochlorous acid concentration 82". At the time when the membrane-free electrolysis is stopped, the amount of hypochlorite ions that reach the anion exchange membrane 50 is extremely small due to the liquid retention capacity of the porous membrane 72. As time passes, the amount of hypochlorite ions passing through the porous membrane 72 increases, and the hypochlorous acid concentration 82 on the surface of the anion exchange membrane 50 also increases. However, as the hypochlorous acid concentration 80 in the electrolytic cell 30 itself decreases, the hypochlorous acid concentration 82 on the surface of the anion exchange membrane 50 also decreases. In the first aqueous solution L1, ionized hypochlorous acid and non-ionized hypochlorous acid exist in equilibrium. The above explanation has focused on ionized hypochlorous acid, but the concentration of non-ionized hypochlorous acid reaching the surface of the anion exchange membrane 50 can be reduced by a similar mechanism.

[0066] The subject of the apparatus, system, or method in this disclosure comprises a computer. The functions of the subject of the apparatus, system, or method in this disclosure are realized by the computer executing a program. The computer comprises a processor as its main hardware component, which operates according to the program. The processor is of any type as long as it can realize its functions by executing the program. The processor consists of one or more electronic circuits, including semiconductor integrated circuits (ICs) or LSIs (Large Scale Integrations). Multiple electronic circuits may be integrated on one chip or provided on multiple chips. Multiple chips may be aggregated in one device or provided on multiple devices. The program is recorded on a non-temporary recording medium such as a ROM, optical disc, or hard disk drive that is readable by the computer. The program may be pre-stored on the recording medium or supplied to the recording medium via a wide-area communication network, including the Internet.

[0067] In this embodiment, since the protective film 70 protects the anion exchange membrane 50, direct contact between the electrolyzed water containing hypochlorite ions generated in the electrolytic cell 30 and the anion exchange membrane 50 can be suppressed. Furthermore, since direct contact between the electrolyzed water containing hypochlorite ions and the anion exchange membrane 50 is suppressed, the deterioration of the anion exchange membrane 50 can be suppressed. In addition, since the protective film 70 protects the anion exchange membrane 50, physical influences such as water flow or bubbles can be suppressed. Furthermore, since physical influences such as water flow or bubbles are suppressed, the deterioration of the anion exchange membrane 50 can be suppressed. Furthermore, since the deterioration of the anion exchange membrane 50 is suppressed, hypochlorous acid gas can be supplied stably for a long period of time without supplying chloride from outside the device. Furthermore, since the deterioration of the anion exchange membrane 50 is suppressed, the frequency of maintenance can be reduced.

[0068] Furthermore, since the protective membrane 70 is composed solely of a porous membrane 72, it can retain liquid due to the surface tension of the porous membrane 72. Also, since the porous membrane 72 is either a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, or a nanofiltration (NF) membrane, it can protect the anion exchange membrane 50. In addition, the surface of the porous membrane 72 is treated to make it hydrophilic, which further enhances its conductivity. Moreover, to compensate for the chloride ions contained in the first aqueous solution L1 that have decreased due to membraneless electrolysis, chloride ions contained in the second aqueous solution L2 stored in the supply tank 40 are supplied to the first aqueous solution L1, so that the purification operation can be continued for a long period of time without supplying chloride ions to the electrolytic cell 30 from the outside, and the purification of the external space R can be continued. Furthermore, by generating bubbles B in the first aqueous solution L1 by bubbling, gas-liquid contact is performed, allowing more hypochlorous acid to be taken into the bubbles B and released into the external space R as mixed air M. The mixed air M containing hypochlorous acid released into the external space R can purify the external space R.

[0069] An overview of one aspect of this disclosure is as follows: (Item 1) An electrolytic cell (30) for storing a first aqueous solution (L1) containing chloride ions, A supply tank (40) for storing a second aqueous solution (L2) containing chloride ions, An anion exchange membrane (50) is provided to connect the electrolytic cell (30) and the supply tank (40), and is permeable to anions containing chloride ions, A protective film (70) is provided on the electrolytic cell (30) side of the anion exchange membrane (50), Equipped with, The electrolytic cell (30) generates hypochlorous acid by performing membrane-free electrolysis of the first aqueous solution (L1), The supply tank (40) supplies the chloride ions contained in the second aqueous solution (L2) to the first aqueous solution (L1) by diaphragm electrolysis, through the anion exchange membrane (50) and the protective membrane (70). The protective film (70) includes a porous film (72) having a network of micropores. Electrolyzed water generator.

[0070] (Item 2) The protective film (70) is Composed solely of the aforementioned porous membrane (72), The electrolytic water generator described in item 1.

[0071] (Item 4) The porous membrane (72) is one of the following: a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, or a nanofiltration (NF) membrane. The electrolytic water generator described in item 1.

[0072] (Item 5) The surface of the porous membrane (72) is subjected to a hydrophilic treatment. The electrolytic water generator described in item 1.

[0073] (Item 6) The electrolytic water generator is provided as described in any one of items 1 to 5, Air introduced from the indoor space flows through the electrolytic cell (30) and is released into the indoor space together with the hypochlorous acid in a purification operation. To compensate for the chloride ions contained in the first aqueous solution (L1) that have been reduced by the aforementioned membrane-free electrolysis, the chloride ions contained in the second aqueous solution (L2) stored in the supply tank (40) are supplied to the first aqueous solution (L1) stored in the electrolytic cell (30) by permeating through the anion exchange membrane (50) and the protective membrane (70). Air purification device (20).

[0074] (Item 7) The air supplied to the electrolytic cell (30) is released as bubbles (B) into the first aqueous solution (L1). The released bubbles (B) are mixed with the hypochlorous acid, and the resulting mixed air (M) is released into the indoor space. The air purification device (20) described in item 6.

[0075] (Example 2) Example 2 relates to a space purification device 20, similar to Example 1. The structure of the protective film 70 in Example 2 differs from that of Example 1. When multiple porous films 72 are arranged adjacent to each other, i.e., stacked, depending on the arrangement of the films, unintended air, such as bubbles, may be mixed in between the films. An example of an arrangement of porous films 72 in which unintended air, such as bubbles, may be mixed in is when the protective film 70 is arranged as porous film 72 / porous film 72 / anion exchange film 50. The porous film 72 is a semipermeable film having a mesh-like structure of fine pores 74. It has liquid retention properties due to the surface tension generated on its fine porous surface, but it has low water permeability and does not actively allow water to pass through. Therefore, when porous films 72 and porous films 72 are arranged adjacent to each other, bubbles and other particles mixed in between adjacent porous films 72 may accumulate between the films, making it difficult to discharge them to the outside of the space purification device 20. If air (bubbles), which are gaseous rather than liquid, are present between the membranes, the current flow for diaphragm electrolysis via the anion exchange membrane 50 is inhibited. This may inhibit the supply of chloride ions from the supply tank 40 to the electrolytic cell 30. Example 2 aims to suppress the inhibition of the supply of chloride ions from the supply tank 40 to the electrolytic cell 30. The following will mainly explain the differences from Example 1.

[0076] Figure 4 is a front cross-sectional view showing the air purification device 20. The protective membrane 70 is composed of two layers: a porous membrane 72 and a water-permeable membrane 76. The water-permeable membrane 76 is positioned on the electrolytic cell 30 side of the anion exchange membrane 50, and the porous membrane 72 is positioned on the electrolytic cell 30 side of the water-permeable membrane 76. In other words, the water-permeable membrane 76 is positioned between the porous membrane 72 and the anion exchange membrane. The porous membrane 72 is a membrane that has water permeability and allows the first aqueous solution L1 to pass through. That is, the anion exchange membrane 50 and the water-permeable membrane 76 are positioned adjacent to each other, and the anion exchange membrane 50 positioned on the electrolytic cell 30 side is covered by the water-permeable membrane 76. Also, the water-permeable membrane 76 and the porous membrane 72 are positioned adjacent to each other, and the water-permeable membrane 76 positioned on the electrolytic cell 30 side is covered by the porous membrane 72.

[0077] Figure 5 is a partially enlarged view of the space purification device 20, the porous membrane 72, and the permeable membrane 76. By arranging the porous membrane 72 / permeable membrane 76 / anion exchange membrane 50, moisture is retained by the permeable membrane 76 placed between the porous membrane 72 and the anion exchange membrane 50. Even if unintended bubbles occur between the porous membrane 72 and the anion exchange membrane 50, the presence of the permeable membrane 76 makes it less likely for the current to flow for diaphragm electrolysis via the anion exchange membrane 50 to be obstructed. In addition, the supply of chloride ions from the supply tank 40 to the electrolytic cell 30 is less likely to be obstructed. Furthermore, by making the protective membrane 70 a two-layer structure of the porous membrane 72 and the permeable membrane 76, the durability of the protective membrane 70 is increased, direct contact between the electrolyzed water containing hypochlorite ions generated in the electrolytic cell 30 and the anion exchange membrane 50 is suppressed, and the deterioration of the anion exchange membrane 50 is further suppressed. The protective film 70 may be arranged in a configuration such as a porous film 72 / permeable film 76 / permeable film 76 / anion exchange film 50, in which a permeable film 76 is laminated.

[0078] According to this embodiment, the protective film 70 consists of a porous membrane 72 with low water permeability, a permeable membrane 76 with high water permeability, and an anion exchange membrane 50, which are layered in sequence. In other words, each membrane is placed adjacent to the others, thus increasing the film thickness and improving the durability of the protective film 70. Furthermore, by layering the porous membrane 72 with low water permeability, the permeable membrane 76 with high water permeability, and the anion exchange membrane 50 in sequence, the amount of water that can be held between the anion exchange membrane 50 and the porous membrane 72 can be increased. In addition, the increased amount of water held between the anion exchange membrane 50 and the porous membrane 72 improves electrical conductivity.

[0079] An overview of one aspect of this disclosure is as follows: (Item 3) The protective film (70) is It is composed of a two-layer structure consisting of the porous membrane (72) and a water-permeable membrane (76) that has water permeability to permeate the first aqueous solution (L1). The permeable membrane (76) is disposed between the porous membrane (72) and the anion exchange membrane (50). The electrolytic water generator described in item 1.

[0080] (Example 3) Examples 1 and 2 are air purification devices 20. Example 3, on the other hand, relates to an electrolytic water generator within the air purification device 20. The electrolytic water generator, excluding the air supply unit 33, blower pipe 34, water recovery unit 36, and discharge port 37 as shown in Figures 1 and 4, includes a discharge pipe for discharging a solution containing hypochlorous acid gas (hereinafter referred to as "electrolytic water") generated by membraneless electrolysis in the electrolytic cell 30. In other words, the electrolytic water generator discharges electrolytic water without releasing mixed air M containing hypochlorous acid. The protective film 70 in Example 3 is configured in the same way as in Examples 1 and 2.

[0081] According to this embodiment, a protective film 70 is used to protect the anion exchange membrane 50 in the electrolytic water generator, thus expanding the range of application.

[0082] The present disclosure has been described above based on examples. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing steps, and that such modifications are also within the scope of the present disclosure. [Explanation of Symbols]

[0083] 20 Space purification device, 30 Electrolytic cell, 31 Electrolytic cell side anode, 32 Electrolytic cell side cathode, 33 Air supply unit, 34 Air blower, 35 Electrolytic cell side internal space, 36 Water recovery unit, 37 Discharge port, 38 Water level detection unit, 40 Supply tank, 41 Supply tank side cathode, 42 Supply tank side internal space, 43 Discharge port, 50 Anion exchange membrane, 60 Current control unit, 61, 62, 63 Wiring, 70 Protective membrane, 72 Porous membrane, 74 Micropores, 76 Water permeable membrane, R External space.

Claims

1. An electrolytic cell for storing a first aqueous solution containing chloride ions, A supply tank for storing a second aqueous solution containing chloride ions, An anion exchange membrane is provided to connect the electrolytic cell and the supply tank, and is permeable to anions containing chloride ions, A protective film provided on the electrolytic cell side of the anion exchange membrane, Equipped with, The electrolytic cell generates hypochlorous acid by performing membrane-free electrolysis of the first aqueous solution. The supply tank supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by diaphragm electrolysis, passing them through the anion exchange membrane and the protective membrane. The protective film includes a porous film having a network of micropores. Electrolyzed water generator.

2. The aforementioned protective film is Composed solely of the aforementioned porous membrane, The electrolytic water generator according to claim 1.

3. The aforementioned protective film is It is composed of a two-layer structure consisting of the porous membrane and a water-permeable membrane that allows the first aqueous solution to pass through. The permeable membrane is disposed between the porous membrane and the anion exchange membrane. The electrolytic water generator according to claim 1.

4. The porous membrane is one of the following: a microfiltration (MF) membrane, an ultrafiltration (UF) membrane, or a nanofiltration (NF) membrane. The electrolytic water generator according to claim 1.

5. The surface of the porous membrane is subjected to a hydrophilic treatment. The electrolytic water generator according to claim 1.

6. The electrolytic water generator is provided according to any one of claims 1 to 5, Air introduced from the indoor space flows through the electrolytic cell and is released into the indoor space together with the hypochlorous acid in a purification operation. To compensate for the chloride ions contained in the first aqueous solution that have decreased due to the aforementioned membraneless electrolysis, the 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 permeating the anion exchange membrane and the protective membrane. Air purification device.

7. The air supplied to the electrolytic cell is released as bubbles into the first aqueous solution. The released bubbles are mixed with the hypochlorous acid, and the resulting mixed air is released into the indoor space. The air purification device according to claim 6.

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