Air purification device

Abstract

Provide a space purification device that can stably generate a desired amount of chlorine dioxide gas without supplying chloride ions (Cl - ) from the outside for a long time. 【Solution means】The space purification device includes an electrolytic cell that electrolyzes a first aqueous solution containing Cl - to generate hypochlorous acid, and a chloride ion supply tank that permeates Cl - contained in a second aqueous solution containing Cl - through an anion exchange membrane and supplies it to the first aqueous solution, and a high-concentration chloride aqueous solution containing Cl - at a higher concentration than the second aqueous solution is stored, and a high-concentration chloride aqueous solution supply tank that supplies the high-concentration chloride aqueous solution to the second aqueous solution. When the purification operation is stopped in a state where the concentration of Cl - contained in the second aqueous solution L2 is thinner than the concentration of Cl - contained in the first aqueous solution, the high-concentration chloride aqueous solution is supplied to the second aqueous solution so that the concentration of Cl - contained in the second aqueous solution L2 becomes higher than the concentration of Cl - contained in the first aqueous solution.

Description

Technical Field

[0001] The present invention relates to a space purification device.

Background Art

[0002] Patent Document 1 discloses an air purification device that uses hypochlorous acid generated by electrolyzing an aqueous sodium chloride solution to remove bacteria, fungi, viruses, odors, etc. contained in the air.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a conventional space purification device is miniaturized, the tank for storing the aqueous solution used for electrolysis also becomes small. When the tank is miniaturized, the amount of the aqueous solution that can be stored decreases compared to the conventional space purification device. Therefore, when electrolysis is repeatedly performed in the miniaturized space purification device, there is a problem that the chloride ion concentration in the aqueous solution easily decreases and the amount of hypochlorous acid generated is unstable.

[0005] The present invention has been made in view of the above problems, and provides a space purification device that can stably generate a desired amount of hypochlorous acid gas without supplying an aqueous solution containing chloride ions from the outside for a long period of time.

Means for Solving the Problems

[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 electrolyzing the first aqueous solution; a chloride ion 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 permeating an anion exchange membrane through diaphragm electrolysis; and a high-concentration chloride aqueous solution supply tank that stores a high-concentration chloride aqueous solution containing a higher concentration of chloride ions than the second aqueous solution and supplies the high-concentration chloride aqueous solution to the second aqueous solution. Air introduced from the indoor space flows through the electrolytic cell and is released into the indoor space together with hypochlorous acid in a purification operation. If the purification operation is stopped when the concentration of chloride ions in the second aqueous solution stored in the chloride ion supply tank is lower than the concentration of chloride ions in the first aqueous solution stored in the electrolytic cell, the high-concentration chloride aqueous solution stored in the high-concentration chloride aqueous solution supply tank is supplied to the second aqueous solution so that the concentration of chloride ions in the second aqueous solution becomes higher than the concentration of chloride ions in the first aqueous solution. [Effects of the Invention]

[0007] The present invention provides a space purification device 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. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a front cross-sectional view showing a space purification device according to an embodiment. [Figure 2] Figure 2 is a block diagram showing the current control unit according to the embodiment. [Figure 3] Figure 3 is a partial cross-sectional plan view along the line III-III in Figure 1, showing each electrolytic unit of the air purification device. [Figure 4] Figure 4 shows a list of chemical reactions occurring in the first aqueous solution stored in the first supply tank of the first diaphragm electrolytic unit and in the third aqueous solution stored in the electrolytic cell. [Figure 5]Figure 5 shows a list of chemical reactions occurring in the first aqueous solution stored in the first supply tank of the second diaphragm electrolytic unit and in the second aqueous solution stored in the second supply tank. [Figure 6] Figure 6 shows a list of reaction equations that occur in the third aqueous solution stored in the electrolytic cell of the diaphragm-free electrolytic unit. [Figure 7] Figure 7 shows the change over time in the chloride ion concentration of the second aqueous solution during the purification operation. [Figure 8] Figure 8 shows the change over time in the chloride ion concentration of the second aqueous solution when the purification operation is stopped and when the purification operation is restarted. [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 showing an air purification device 1 according to an embodiment. The air purification device 1 performs electrolysis of a first aqueous solution L1 containing chloride ions in an electrolytic cell 10 (described later) to generate and volatilize hypochlorous acid. The air purification device 1 releases the volatilized hypochlorous acid into an indoor space R which is outside the housing C that constitutes the air purification device 1, thereby removing bacteria, fungi, viruses, or odors contained in the air of the indoor space R in which the air purification device 1 is installed. The indoor space R is the space in which the air purification device 1 is installed and which is the target of air purification. The indoor space R is also the space outside the housing C of the air purification device 1, so it may also be called the "external space".

[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, and more specifically, includes, for example, the inside of a bathroom heater / dryer, the inside of an air conditioner, around a fan, around a circulator, around a ceiling fan, inside a humidifier, 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 chloride ion supply tank 20, a high-concentration chloride aqueous solution supply tank 30, an anion exchange membrane 41, and a current control unit 60. The air purification device 1 may further include a cation exchange membrane 42 and a metal ion supply tank 50. In this embodiment, an example in which the cation exchange membrane 42 and the metal ion supply tank 50 are included will be described.

[0013] The housing C houses the electrolytic cell 10, chloride ion supply tank 20, high-concentration chloride aqueous solution supply tank 30, metal ion supply tank 50, anion exchange membrane 41, cation exchange membrane 42, and current control unit 60. In other words, the air purification device 1 may be an integrated unit within the housing C. The shape of the housing C can be appropriately changed depending on the location where the air purification device 1 is installed, and may be, for example, rectangular or cylindrical. The air purification device 1 is small enough to be housed inside, for example, an air conditioner, and if the shape of the housing C is rectangular, it is, for example, about 10 cm × 7 cm × 4 cm.

[0014] Electrolytic cell 10 and chloride ion supply tank 2, assuming continuous use of 8 hours per day for one year. 0. The volumes of the high-concentration chloride aqueous solution supply tank 30 and the metal ion supply tank 50 will be described. For example, it is preferable that the volume of the chloride ion supply tank 20 be approximately 8 times or more the volume of the electrolytic cell 10. Alternatively, for example, the volume ratio of the chloride ion supply tank 20 to the high-concentration chloride aqueous solution supply tank 30 may be 2:3. Alternatively, for example, it is preferable that the volume of the metal ion supply tank 50 be approximately 4 times or more the volume of the electrolytic cell 10. By using such volume ratios, the chloride ion supply tank 20 and the high-concentration chloride aqueous solution supply tank 30 can store a second aqueous solution L2 containing a sufficient amount of chloride ions necessary to supply the first aqueous solution L1 stored in the electrolytic cell 10, as well as a high-concentration chloride aqueous solution HC. The metal ion supply tank 50 can store a third aqueous solution L3 containing a sufficient amount of metal ions (metal ions selected from the group consisting of sodium ions, lithium ions, and potassium ions, as described later) necessary to supply the first aqueous solution L1 stored in the electrolytic cell 10.

[0015] Therefore, chloride ions can be stably supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 10. Similarly, the required amount of metal ions can be stably supplied from the third aqueous solution L3 stored in the metal ion supply tank 50 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] The electrolytic cell 10, chloride ion supply tank 20, high-concentration chloride aqueous solution supply tank 30, and metal ion supply tank 50 are arranged in the following order from the negative x-axis side when viewed from the front: metal ion supply tank 50, electrolytic cell 10, chloride ion supply tank 20, and high-concentration chloride aqueous solution supply tank 30. An anion exchange membrane 41 is placed between the electrolytic cell 10 and the chloride ion supply tank 20. A cation exchange membrane 42 is placed between the electrolytic cell 10 and the metal ion supply tank 50. For example, if the surfaces facing each other between the electrolytic cell 10 and the chloride ion supply tank 20 are formed by a frame-shaped member, the anion exchange membrane 41 may be fitted into the frame-shaped member. Similarly, if the surfaces facing each other between the electrolytic cell 10 and the metal ion supply tank 50 are formed by a frame-shaped member, the cation exchange membrane 42 may be fitted into the frame-shaped member. The current control unit 60 is placed at any position within the housing C.

[0017] [Electrolytic cell 10] The electrolytic cell 10 is a tank for storing a first aqueous solution L1 containing chloride ions. The electrolytic cell 10 has a box-like shape, for example. Figure 1 shows the electrolytic cell 10 with the first aqueous solution L1 stored inside. The first aqueous solution L1 is, for example, an aqueous solution in which an electrically conductive electrolyte is dissolved, 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.

[0018] 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 860 mmol / L, or 171 mmol / L. In other words, for example, the mass percentage concentration of a dilute sodium chloride aqueous solution or a dilute potassium chloride aqueous solution may be 17 mmol / L to 860 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.

[0019] The electrolytic cell 10 includes an electrolytic cell-side anode 11, an electrolytic cell-side cathode 12, an air supply unit 13, a blower pipe 14, an electrolytic cell-side internal space 15, a water recovery unit 16, and a discharge port 17. The electrolytic cell 10 may further include a water level detection unit 18.

[0020] The electrolytic cell anode 11 and the electrolytic cell cathode 12 are a pair of electrodes used for the electrolysis of the first aqueous solution L1. The electrolytic cell anode 11 and the electrolytic cell cathode 12 are each inserted into the electrolytic cell 10 from the outside toward the inside. The electrolytic cell anode 11 and the electrolytic cell cathode 12 each have a plate-like shape. The plate-like shape includes rectangular and rectangular shapes.

[0021] Insoluble electrodes may be used as the electrolytic cell anode 11 and the electrolytic cell cathode 12. More specifically, for example, platinum-iridium titanium electrodes, platinum electrodes, ruthenium titanium electrodes, or iridium titanium oxide electrodes may be used.

[0022] There is no diaphragm, such as an ion exchange membrane, between the electrolytic cell anode 11 and the electrolytic cell cathode 12. In other words, the electrolysis of the first aqueous solution L1 performed using the pair of electrolytic cell anodes 11 and cathodes 12 is diaphragm-free electrolysis. Hypochlorous acid, which is used for purifying the indoor space R, is generated by the diaphragm-free electrolysis of the first aqueous solution L1 performed using the pair of electrolytic cell anodes 11 and cathodes 12.

[0023] The yz plane on the negative x-axis side of the electrolytic cell anode 11 and the yz plane on the positive x-axis side of the electrolytic cell cathode 12 are positioned opposite each other. This arrangement allows for a uniform electric field to be generated between the electrolytic cell anode 11 and the electrolytic cell cathode 12. Because electrolysis occurs uniformly, the current between the two electrodes is also uniformly distributed. Therefore, the degradation of the catalyst layer on the surface of each electrode occurs uniformly, and even when electrolysis is performed repeatedly, the non-uniform degradation of the catalyst layer on the surface of each electrode caused by a non-uniform electric field can be suppressed. Consequently, a decrease in electrolysis efficiency can be suppressed.

[0024] The air supply unit 13 is a blower or a predetermined opening that introduces air from the indoor space R into the electrolytic cell 10. If the air supply unit 13 is an opening, it is preferable to place it at any position that allows air to circulate to the opening, such as a circulator, fan, or ceiling fan located inside the bathroom heating and drying unit, inside the air conditioner, or outside the air purification device 1.

[0025] The air blower pipe 14 is a tubular member that connects the air supply unit 13 and the electrolytic cell 10. One end of the air supply unit 13 is located on the side of the indoor space R, and the other end is connected to the air blower pipe 14 side. One end of the air blower pipe 14 is connected to the side of the air supply unit 13, and the other end is connected to the side of the electrolytic cell 10. The end of the air blower pipe 14 located on the side of the electrolytic cell 10 is 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.

[0026] The air supply unit 13 supplies air from the indoor space R to the first aqueous solution L1 stored in the electrolytic cell 10 via the air blower pipe 14. The air introduced into the first aqueous solution L1 via the air supply unit 13 and the air blower pipe 14 is released as bubbles B.

[0027] The internal space 15 on the electrolytic cell side 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 internal space 15 on the electrolytic cell side.

[0028] The water recovery unit 16 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 indoor space R as a liquid and returns it to the electrolytic cell 10. The water recovery unit 16 is, for example, a Peltier element that can cool and condense moisture contained in the air into water droplets. The water recovery unit 16 may be placed at the discharge port 17 through which the air passes when it is released into the indoor space R in order to recover moisture contained in the air that flows through the inside of the air purification device 1. When the water recovery unit 16 is placed at the discharge port 17, moisture contained in the air that has flowed through the inside of the air purification device 1 can be recovered efficiently. Note that the water recovery unit 16 is located in the internal space on the electrolytic cell side. It may be placed at any position among the 15.

[0029] The discharge port 17 is an opening for releasing mixed air M, which is a mixture of air flowing in from the air supply unit 13 and hypochlorous acid generated from the first aqueous solution L1 by membraneless electrolysis, into the interior space R of the housing C. In Figure 1, as an example, the discharge port 17 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 17 is cylindrical, including, for example, cylindrical or rectangular tubes. 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 17 may be a hole-like opening provided in a part of the upper surface of the electrolytic cell 10. Alternatively, the discharge port 17 and the upper surface of the housing C (the surface on the positive z-axis side) may be formed as a single integrated unit.

[0030] The discharge port 17 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.

[0031] In the air purification device 1 according to this embodiment, air introduced from the indoor space R flows through the electrolytic cell 10 and is released back into the indoor space R along with hypochlorous acid in a purification operation. The airflow path A shown by the white arrows and upward-sloping arrows in Figure 1 is a series of paths through which air supplied from the indoor space R to the air purification device 1 flows through the electrolytic cell 10 and is released back into the indoor space R as mixed air M containing hypochlorous acid. In other words, the airflow path A shows the flow of air from the indoor space R, the air supply unit 13, the blower pipe 14, the first aqueous solution L1 stored in the electrolytic cell 10, the internal space on the electrolytic cell side 15, the water recovery unit 16, the discharge port 17, and back into the indoor space R.

[0032] More specifically, in the airflow channel A, as shown in Figure 1, bubbles B are released from the indoor space R through the air supply unit 13 and the air blower 14 into the first aqueous solution L1 stored in the electrolytic cell 10. In other words, bubbles B are generated by bubbling the first aqueous solution L1 with air introduced from the indoor space R. Bubbles B and hypochlorous acid generated by the membraneless electrolysis of the first aqueous solution L1 are mixed to form mixed air M.

[0033] 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 15 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 17 via the water recovery unit 16 into the indoor space R. The hypochlorous acid gas that has volatilized and gasified into the internal space 15 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 17 via the water recovery unit 16 into the indoor space R.

[0034] 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 room 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 16 and returned to the first aqueous solution L1 as water droplets.

[0035] The mixed air M containing hypochlorous acid, released from the discharge port 17 into the indoor space R of the air purification device 1, purifies the indoor space R. In other words, the mixed air M containing hypochlorous acid removes bacteria, fungi, viruses, or odors contained in the air of the indoor space R of the enclosure C.

[0036] The electrolytic cell 10 may further include a water level detection unit 18. The water level detection unit 18 detects the position of the liquid surface S1 in the first aqueous solution L1. The water level detection unit 18 is, for example, a water level sensor. The water level detection unit 18 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 anode 11 and the electrolytic cell cathode 12.

[0037] If the air purification device 1 is equipped with a water level detection unit 18, the water recovery unit 16 supplies water to the electrolytic cell 10 based on the position of the liquid level S1 detected by the water level detection unit 18. More specifically, the water recovery unit 16 supplies water to the electrolytic cell 10 so that it does not fall below the upper ends (the portion on the positive z-axis side) of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. Furthermore, the water recovery unit 16 supplies water to the electrolytic cell 10 so that it does not fall below the upper end (the portion on the positive z-axis side) of the air blower pipe 14 connected to the electrolytic cell 10.

[0038] If the air purification device 1 is equipped with a water recovery unit 16 and a water level detection unit 18, the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 can remain immersed in the first aqueous solution L1. Therefore, exposure of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 to air as the first aqueous solution L1 decreases can be suppressed, and the electrolysis efficiency of membrane-free electrolysis can be maintained. The chloride ion supply tank 20 and the metal ion supply tank 50 may also be equipped with water recovery units and water level detection units similar to those of the electrolytic cell 10.

[0039] [Chloride ion supply tank 20] The chloride ion 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. Figure 1 shows the state in which the second aqueous solution L2 is stored in the chloride ion supply tank 20.

[0040] As the solute for the second aqueous solution L2, a substance with a GHS (Globally Harmonized System of Classification and Labelling of Chemicals) classification that has a level of safety equivalent to sodium chloride is preferred 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. By performing the first diaphragm electrolysis described later, the metal ions contained in the second aqueous solution L2 react with hydroxide ions generated by the first diaphragm electrolysis to form a precipitate of metal hydroxide.

[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 10%. As an example, when the second aqueous solution L2 is a magnesium chloride aqueous solution, the magnesium ions contained in the magnesium chloride aqueous solution react with the hydroxide ions produced by the first diaphragm electrolysis, as described later, 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 chloride ion supply tank 20 includes a chloride ion supply tank side cathode 21, a chloride ion supply tank side internal space 22, and a first outlet 23.

[0043] The chloride ion supply tank side cathode 21 is inserted into the chloride ion supply tank 20 from the outside toward the inside. The chloride ion supply tank side cathode 21 has a plate-like shape. The plate-like shape includes rectangular and rectangular shapes. The chloride ion supply tank side cathode 21 is used in the first diaphragm electrolysis via the anion exchange membrane 41 as a pair with the electrolytic cell side anode 11, which will be described later. Details of the first diaphragm electrolysis will be described later with reference to Figure 3. Chloride ions are supplied from the second aqueous solution L2 to the first aqueous solution L1 by the first diaphragm electrolysis of the second aqueous solution L2, which is performed using the pair of chloride ion supply tank side cathodes 21 and the electrolytic cell side anode 11.

[0044] An insoluble electrode may be used as the chloride ion supply tank side cathode 21. More specifically, For example, platinum-iridium titanium electrodes, platinum electrodes, ruthenium titanium electrodes, or iridium oxide titanium electrodes may be used.

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

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

[0047] [High-concentration chloride solution supply tank 30] The high-concentration chloride aqueous solution supply tank 30 is a tank for storing a high-concentration chloride aqueous solution HC containing a higher concentration of chloride ions than the second aqueous solution L2, and for supplying the high-concentration chloride aqueous solution HC to the second aqueous solution L2 stored in the chloride ion supply tank 20.

[0048] Chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by the first diaphragm electrolysis described later, and are reduced. During the purification operation, the high-concentration chloride aqueous solution HC stored in the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 to replenish the chloride ions contained in the second aqueous solution L2 that have been reduced by the first diaphragm electrolysis. Also, when the purification operation is stopped, the high-concentration chloride aqueous solution HC stored in the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 so that the concentration of chloride ions contained in the second aqueous solution L2 becomes higher than the concentration of chloride ions contained in the first aqueous solution L1. The operation of supplying the high-concentration chloride aqueous solution HC to the second aqueous solution L2 during the purification operation and when the purification operation is stopped will be described later.

[0049] The high-concentration chloride aqueous solution HC is a solution obtained by increasing the concentration of the second aqueous solution L2. When the high-concentration chloride aqueous solution HC is a high-concentration magnesium chloride aqueous solution, the mass percentage concentration is, for example, about 25% to 35%. Preferably, the high-concentration chloride aqueous solution HC is a saturated magnesium chloride aqueous solution.

[0050] The high-concentration chloride aqueous solution supply tank 30 is equipped with a delivery unit 31. The delivery unit 31 delivers the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 to the chloride ion supply tank 20. The delivery unit 31 is, for example, a liquid pump. The delivery unit 31 is positioned from the chloride ion supply tank 20 to the high-concentration chloride aqueous solution supply tank 30. The delivery unit 31 is equipped with a suction-side tube 32 that draws in the high-concentration chloride aqueous solution HC, and a dropping-side tube 33 positioned on the chloride ion supply tank 20 side that drops the high-concentration chloride aqueous solution HC drawn in from the high-concentration chloride aqueous solution supply tank 30 into the second aqueous solution L2. The flow of the high-concentration chloride aqueous solution HC drawn in by the suction-side tube 32 (positive z-axis direction) and the flow of the high-concentration chloride aqueous solution HC dropped into the second aqueous solution L2 by the dropping-side tube 33 (negative z-axis direction) are indicated by thin white arrows.

[0051] [Metal ion supply tank 50] The metal ion supply tank 50 stores the third aqueous solution L3 containing metal ions, and the third aqueous solution L3 This is a tank for supplying metal ions contained in the first aqueous solution L1. Figure 1 shows the state in which the third aqueous solution L3 is stored in the metal ion supply tank 50.

[0052] For the solute of the third aqueous solution L3, a substance with a GHS classification equivalent to that of sodium chloride is preferred to ensure safety in the event of leakage. Specifically, the third aqueous solution L3 is an aqueous solution of a metal compound containing at least one metal ion selected from the group consisting of sodium ions, lithium ions, and potassium ions. That is, the metal ions contained in the third aqueous solution L3 may be one or more selected from the group consisting of sodium ions, lithium ions, and potassium ions, and may be a combination of two or three types.

[0053] More specifically, preferably, the third aqueous solution L3 is at least one aqueous solution selected from the group consisting of disodium hydrogen phosphate (Na2HPO4) aqueous solution, sodium bicarbonate (NaHCO3) aqueous solution, lithium carbonate (LiCO3) aqueous solution, and potassium carbonate (K2CO3) aqueous solution. That is, the third aqueous solution L3 may be one or more selected from the group consisting of disodium hydrogen phosphate aqueous solution, sodium bicarbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution, and may be a combination of two, three, or four types. The disodium hydrogen phosphate aqueous solution, sodium bicarbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution may be saturated disodium hydrogen phosphate aqueous solution, saturated sodium bicarbonate aqueous solution, saturated lithium carbonate aqueous solution, and saturated potassium carbonate aqueous solution, respectively. In this specification, "saturated" includes cases where the solute precipitates without dissolving in water. The more specific amounts of solute dissolved in the aqueous solutions are as follows. The amounts of solute dissolved in the aqueous solutions shown below include both the concentration at the initial state when the air purification device 1 is started to be used and the concentration when the concentration of the third aqueous solution L3 decreases with the use of the air purification device 1.

[0054] When using a disodium hydrogen phosphate aqueous solution as the third aqueous solution L3, the amount of disodium hydrogen phosphate aqueous solution that dissolves is, for example, 1g to 8g per 100g of water.

[0055] The metal ion supply tank 50 includes a metal ion supply tank side anode 51, a metal ion supply tank side internal space 52, and a second outlet 53.

[0056] The metal ion supply tank-side anode 51 is inserted into the metal ion supply tank 50 from the outside toward the inside. The metal ion supply tank-side anode 51 has a plate-like shape. The plate-like shape includes rectangular and rectangular shapes. The metal ion supply tank-side anode 51 is used in conjunction with the chloride ion supply tank-side cathode 21, which will be described later, in the second diaphragm electrolysis via the cation exchange membrane 42. Details of the second diaphragm electrolysis will be described later with reference to Figure 3. Metal ions are supplied from the third aqueous solution L3 to the first aqueous solution L1 by the second diaphragm electrolysis of the third aqueous solution L3, which is performed using the pair of metal ion supply tank-side anodes 51 and the electrolytic cell-side cathode 12.

[0057] An insoluble electrode may be used as the anode 51 on the metal ion supply tank side. More specifically, for example, a platinum-iridium titanium electrode, a platinum electrode, a ruthenium titanium electrode, or an iridium titanium oxide electrode may be used.

[0058] The internal space 52 on the metal ion supply tank side is the upper space (space on the positive z-axis side) formed above the liquid surface S3 of the third aqueous solution L3 when the third aqueous solution L3 is stored in the metal ion supply tank 50. In other words, the third aqueous solution L3 is not stored up to the upper interior surface of the metal ion supply tank 50 (the xy plane on the positive z-axis side), and the metal ion supply tank 50 has the internal space 52 on the metal ion supply tank side.

[0059] The second outlet 53 is an opening for discharging oxygen generated by the second diaphragm electrolysis of the third aqueous solution L3 into the indoor space R of the housing C. The second outlet 53 is, for example, a check valve. When a check valve is used as the second outlet 53, the oxygen inside the metal ion supply tank 50 is discharged into the indoor space R, but the inflow of gases such as air from the indoor space R can be suppressed. When the second diaphragm electrolysis of the third aqueous solution L3 is repeated, oxygen accumulates in the internal space 52 on the metal ion supply tank side, and the internal pressure of the metal ion supply tank 50 increases. This pressure causes the check valve of the second outlet 53 to open, and oxygen is discharged into the indoor space R of the metal ion supply tank 50.

[0060] [Anion exchange membrane 41] The anion exchange membrane 41 is a membrane-like member that connects the electrolytic cell 10 and the chloride ion supply tank 20 in a way that allows anions to pass through, based on the voltage applied between the electrolytic cell 10 and the chloride ion supply tank 20. More specifically, when a voltage is applied between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21, a first diaphragm electrolysis is performed via the anion exchange membrane 41. Through the first diaphragm electrolysis using the electrolytic cell anode 11 and the chloride ion supply tank cathode 21, chloride ions contained in the second aqueous solution L2 permeate the anion exchange membrane 41 and are supplied to the first aqueous solution L1 (indicated by the negative x-axis direction and thick black arrow).

[0061] The anion exchange membrane 41 in this embodiment is not a type of membrane that allows anions to permeate by osmosis without using electricity. Furthermore, magnesium ions, which are cations, do not permeate the anion exchange membrane 41. 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 41 during the first diaphragm electrolysis using the electrolytic cell side anode 11 and the chloride ion supply tank side cathode 21, magnesium ions, which are cations, do not permeate the anion exchange membrane 41. The anion exchange membrane 41 is, for example, a hydrocarbon-based anion exchange membrane, and includes membranes that have properties such as selective permeability of monovalent anions, alkali resistance, and high temperature resistance.

[0062] The plane on the anion exchange membrane 41 side of the electrolytic cell anode 11 (yz plane on the positive x-axis) and the plane on the anion exchange membrane 41 side of the chloride ion supply tank cathode 21 (yz plane on the negative x-axis) are positioned opposite each other. This arrangement allows for a uniform electric field to be generated between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21. Because electrolysis occurs uniformly, the current between the two electrodes is also uniformly distributed. Therefore, the deterioration of the catalyst layer on the surface of each electrode occurs uniformly, and even when electrolysis is performed repeatedly, the non-uniform deterioration of the catalyst layer on the surface of each electrode caused by a non-uniform electric field can be suppressed. Consequently, a decrease in electrolysis efficiency can be suppressed.

[0063] Furthermore, the electrolytic cell-side anode 11 and the chloride ion supply tank-side cathode 21 are positioned in close proximity to the anion exchange membrane 41. In this specification, "close proximity" includes both a state in which the electrolytic cell-side anode 11 and the chloride ion supply tank-side cathode 21 are close to the anion exchange membrane 41 while maintaining a predetermined distance from each other, and a state in which the electrolytic cell-side anode 11 and the chloride ion supply tank-side cathode 21 are in contact with the anion exchange membrane 41.

[0064] [Cation exchange membrane 42] The cation exchange membrane 42 is a membrane-like member that connects the electrolytic cell 10 and the metal ion supply tank 50 in a way that allows cations to pass through, based on the voltage applied between the electrolytic cell 10 and the metal ion supply tank 50. More specifically, when a voltage is applied between the electrolytic cell 10 and the metal ion supply tank 50, a second diaphragm electrolysis is performed via the cation exchange membrane 42. Through the second diaphragm electrolysis using the cathode 12 on the electrolytic cell side and the anode 51 on the metal ion supply tank side, metal ions contained in the third aqueous solution L3 are supplied to the first aqueous solution L1 by permeating through the cation exchange membrane 42 (indicated by a thick white arrow in the positive x-axis direction).

[0065] The cation exchange membrane 42 in this embodiment is not a type of cation exchange membrane that allows cations to permeate by osmosis without using electricity. Furthermore, the cation exchange membrane 42 does not allow hydroxide ions, which are anions, to permeate. More specifically, the electrolytic cell side cathode 12 and the metal ion supply tank When metal ions contained in the third aqueous solution L3 are supplied to the first aqueous solution L1 by the second diaphragm electrolysis using the side anode 51, they permeate the cation exchange membrane 42, while hydroxide ions, which are anions, do not permeate the cation exchange membrane 42.

[0066] The plane on the cation exchange membrane 42 side of the electrolytic cell-side cathode 12 (yz plane on the negative x-axis) and the plane on the cation exchange membrane 42 side of the metal ion supply tank-side anode 51 (yz plane on the positive x-axis) are positioned opposite each other. This arrangement allows for a uniform electric field to be generated between the electrolytic cell-side cathode 12 and the metal ion supply tank-side anode 51. Because electrolysis occurs uniformly, the current between the two electrodes is also uniformly distributed. Therefore, the degradation of the catalyst layer on the surface of each electrode occurs uniformly, and even when electrolysis is performed repeatedly, the non-uniform degradation of the catalyst layer on the surface of each electrode caused by a non-uniform electric field can be suppressed. Consequently, a decrease in electrolysis efficiency can be suppressed.

[0067] Furthermore, the electrolytic cell-side cathode 12 and the metal ion supply tank-side anode 51 are positioned in close proximity to the cation exchange membrane 42. In this specification, "close proximity" includes both a state in which the electrolytic cell-side cathode 12 and the metal ion supply tank-side anode 51 are close to the cation exchange membrane 42 while maintaining a predetermined distance from each other, and a state in which the electrolytic cell-side cathode 12 and the metal ion supply tank-side anode 51 are in contact with the cation exchange membrane 42.

[0068] [Current control unit 60] The current control unit 60 controls the current used in the non-diaphragm electrolysis, the first diaphragm electrolysis, and the second diaphragm electrolysis described later. Furthermore, based on the voltage values ​​applied in the non-diaphragm electrolysis (corresponding to "electrolysis" in the claim) and the first diaphragm electrolysis (corresponding to "diaphragm electrolysis" in the claim) obtained by the current control unit 60, the supply unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2.

[0069] Here, the configuration of the current control unit 60 will be explained using Figure 2. Figure 2 is a block diagram of the current control unit 60 according to an embodiment. As shown in Figure 2, the current control unit 60 includes a voltage acquisition unit 60a, a calculation unit 60b, an estimation unit 60c, and a storage unit 60d.

[0070] The voltage acquisition unit 60a is a device capable of acquiring the voltage value applied between electrodes, such as a voltmeter. The voltage values ​​acquired by the voltage acquisition unit 60a are of two types, such as (1) the first voltage value and (2) the second voltage value, as described below.

[0071] (1) First voltage value The voltage acquisition unit 60a acquires a first voltage value applied between the electrolytic cell anode 11 and the electrolytic cell cathode 12. The calculation unit 60b calculates the conductivity of the first aqueous solution L1 based on the first voltage value acquired by the voltage acquisition unit 60a. The estimation unit 60c estimates the chloride ion concentration of the first aqueous solution L1 based on the conductivity of the first aqueous solution L1 calculated by the calculation unit 60b.

[0072] (2) Second voltage value The voltage acquisition unit 60a acquires a second voltage value (the "voltage value" in the claim) applied between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21. The calculation unit 60b calculates the conductivity of the second aqueous solution L2 based on the second voltage value acquired by the voltage acquisition unit 60a and the conductivity of the first aqueous solution L1. The estimation unit 60c estimates the chloride ion concentration of the second aqueous solution L2 based on the conductivity of the second aqueous solution L2 calculated by the calculation unit 60b. The second voltage value is correlated with the chloride ion concentration of the second aqueous solution L2. An increase in the second voltage value indicates a decrease in the chloride ion concentration in the second aqueous solution L2, and a decrease in the second voltage value indicates an increase in the chloride ion concentration in the second aqueous solution L2.

[0073] Furthermore, the calculation unit 60b calculates the chloride ion concentration of the first aqueous solution L1 estimated from the first voltage value. The estimation unit 60c calculates the relative magnitudes of chloride ion concentrations in the second aqueous solution L2 estimated from the second voltage value. Based on the relative magnitudes calculated by the calculation unit 60b, the estimation unit 60c estimates the state of chloride ion concentration in the second aqueous solution L2 (first state P1 or second state P2), which will be described later.

[0074] Furthermore, the calculation unit 60b calculates the amount of high-concentration chloride solution HC to be supplied to the second aqueous solution L2, which is necessary to bring the second aqueous solution L2 to the desired concentration, based on the concentration of chloride ions contained in the second aqueous solution L2 estimated from the second voltage value. Here, the "desired concentration" is, for example, the same concentration as the concentration of chloride ions contained in the first aqueous solution L1 estimated from the first voltage value during the purification operation. The discharge unit 31 then supplies the high-concentration chloride solution HC to the second aqueous solution L2 based on the amount of high-concentration chloride solution HC supplied by the calculation unit 60b. This supply operation will be described later.

[0075] The memory unit 60d stores the first voltage value and the second voltage value acquired by the voltage acquisition unit 60a during the purification operation. Therefore, the conductivity calculation by the calculation unit 60b described above may be based on the first voltage value and the second voltage value stored in the memory unit 60d. In this case, the memory unit 60d outputs each of the stored pieces of information in response to a request from the calculation unit 60b.

[0076] The memory unit 60d may store information relating to the relationship between the first voltage value and the chloride ion concentration of the first aqueous solution L1, and information relating to the relationship between the second voltage value and the chloride ion concentration of the second aqueous solution L2. Each piece of information stored in the memory unit 60d is information that has been previously identified through experiments or other means. In this case, the memory unit 60d outputs each piece of stored information in response to a request from the estimation unit 60c.

[0077] As described above, the current control unit 60 controls the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the first and second voltage values ​​acquired by the voltage acquisition unit 60a. As a result, as will be described later, the purification operation can be performed when the chloride ion concentration of the second aqueous solution L2 is lower than that of the first aqueous solution L1 (second state P2), and the purification operation can be stopped when the chloride ion concentration of the second aqueous solution L2 is higher than that of the first aqueous solution L1 (first state P1).

[0078] The memory unit 60d may further store the correspondence between the amount of hypochlorous acid gas generated and the amount of current used in the diaphragmless electrolysis described later. The information stored in the memory unit 60d is information that has been identified in advance through experiments or other means. The current control unit 60 controls the third current used in the diaphragmless electrolysis described later, based on the information stored in the memory unit 60d. This current control will be described later.

[0079] The memory unit 60d may further store the correspondence between the amount of chloride ions reduced by the purification operation and the duration of the purification operation. The information stored in the memory unit 60d is information that has been identified in advance through experiments or other means. The current control unit 60 controls the first current used in the first diaphragm electrolysis, which will be described later, based on the information stored in the memory unit 60d. This current control will be described later.

[0080] The memory unit 60d may further store the correspondence between the decrease in chloride ions and sodium ions due to salt evaporation (described later) and the time of the purification operation. The information stored in the memory unit 60d is information that has been identified in advance through experiments or other means. The current control unit 60 controls the second current used in the second diaphragm electrolysis (described later) based on the information stored in the memory unit 60d. This current control will be described later.

[0081] As described above, the current control unit 60, based on the information stored in the memory unit 60d, performs the following operation: The current used in diaphragm electrolysis, first diaphragm electrolysis, and second diaphragm electrolysis is controlled. This allows chloride ions and sodium ions consumed by the first aqueous solution L1 to be supplied appropriately from the second aqueous solution L2 and the third aqueous solution L3, respectively, thereby providing a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas.

[0082] The current control unit 60 includes wiring 61 to 64. Wiring 61 to 64 are lines through which current flows. The chloride ion supply tank side cathode 21 is electrically connected to the current control unit 60 via wiring 61, the electrolytic cell side anode 11 via wiring 62, the electrolytic cell side cathode 12 via wiring 63, and the metal ion supply tank side anode 51 via wiring 64. Parts of each electrode may protrude outside each tank and be connected to the respective wiring.

[0083] Next, referring to Figure 3, the first diaphragm electrolytic unit E1, the second diaphragm electrolytic unit E2, and the non-diaphragm electrolytic unit E3 of the air purification device 1 according to this embodiment will be described.

[0084] Figure 3 is a partial cross-sectional plan view along the line III-III in Figure 1, showing each electrolytic unit of the air purification device 1. In Figure 3, the first diaphragm electrolytic unit E1 is shown as the area enclosed by a dashed rectangle, the second diaphragm electrolytic unit E2 as the area enclosed by a double-dash rectangle, and the non-diaphragm electrolytic unit E3 as the area enclosed by a dashed rectangle.

[0085] The first diaphragm electrolytic unit E1 is provided across the electrolytic cell 10 and the chloride ion supply tank 20. The first diaphragm electrolytic unit E1 comprises an electrolytic cell-side anode 11, a chloride ion supply tank-side cathode 21, and an anion exchange membrane 41. The first diaphragm electrolytic unit E1 performs first diaphragm electrolysis via the anion exchange membrane 41 by passing a first current between a pair of electrolytic cell-side anodes 11 and chloride ion supply tank-side cathodes 21.

[0086] The second diaphragm electrolytic unit E2 is provided across the chloride ion supply tank 20 and the metal ion supply tank 50, with the electrolytic cell 10 interposed between them. The second diaphragm electrolytic unit E2 comprises a cathode 21 on the chloride ion supply tank side, an anode 51 on the metal ion supply tank side, an anion exchange membrane 41, and a cation exchange membrane 42. The second diaphragm electrolytic unit E2 performs second diaphragm electrolysis via the anion exchange membrane 41 and the cation exchange membrane 42 by passing a second current between the pair of cathodes 21 on the chloride ion supply tank side and anodes 51 on the metal ion supply tank side.

[0087] The diaphragm-free electrolysis unit E3 is provided in the electrolytic cell 10. The diaphragm-free electrolysis unit E3 comprises an electrolytic cell-side anode 11 and an electrolytic cell-side cathode 12. The diaphragm-free electrolysis unit E3 generates hypochlorous acid by performing diaphragm-free electrolysis on the first aqueous solution L1 by passing a third current between the pair of electrolytic cell-side anodes 11 and electrolytic cell-side cathodes 12.

[0088] As explained above, the chloride ion supply tank side cathode 21 is used for the first diaphragm electrolysis and the second diaphragm electrolysis, and the electrolytic cell side anode 11 is used for the first diaphragm electrolysis and non-diaphragm electrolysis.

[0089] The current control unit 60 (see Figures 1 and 2) controls the first current used in the first diaphragm electrolysis, the second current used in the second diaphragm electrolysis, and the third current used in the non-diaphragm electrolysis. In other words, the current control unit 60 can control the chemical reactions occurring in the first diaphragm electrolysis unit E1, the second current flowing through the second diaphragm electrolysis unit E2, and the third current flowing through the non-diaphragm electrolysis unit E3 by controlling the first current flowing through the first diaphragm electrolysis unit E1, the second current flowing through the second diaphragm electrolysis unit E2, and the non-diaphragm electrolysis unit E3.

[0090] The following diagrams, using Figures 4 to 6, illustrate the chemical reactions occurring in the first diaphragm electrolytic section E1 and the second diaphragm electrolytic section. The chemical reactions occurring in section E2 and in the non-diaphragm electrolytic section E3 will be described in detail. Furthermore, the following description will focus on the case where the first aqueous solution L1 is a sodium chloride aqueous solution, the second aqueous solution L2 is a magnesium chloride aqueous solution, and the third aqueous solution L3 is a disodium hydrogen phosphate aqueous solution.

[0091] [First diaphragm electrolytic section E1] In the first diaphragm electrolytic unit E1, reactions occur at both the electrolytic cell-side anode 11 and the chloride ion supply tank-side cathode 21 via the anion exchange membrane 41. That is, in the first diaphragm electrolytic unit E1, reactions occur at both the first aqueous solution L1 stored in the electrolytic cell 10 and the second aqueous solution L2 stored in the chloride ion supply tank 20.

[0092] Figure 4 shows a list of chemical reactions occurring in the first aqueous solution L1 stored in the electrolytic cell 10 of the first diaphragm electrolytic unit E1 and in the second aqueous solution L2 stored in the chloride ion supply tank 20.

[0093] When a predetermined voltage is applied to the first diaphragm electrolytic unit E1, a first current flows, electrons move, and the chemical reaction shown in Figure 4 occurs. Note that the chemical reactions (a) to (f) in Figure 4, which occur in the first aqueous solution L1 stored in the electrolytic cell 10, also occur in the non-diaphragm electrolytic unit E3 in the same manner as described below.

[0094] First, referring to Figures 4(a) to (f), we will explain the reactions that occur in the first aqueous solution L1 stored in the electrolytic cell 10.

[0095] <Electrolytic cell 10 (first aqueous solution L1)> Figure 4(a): Anion exchange membrane 41 When a voltage is applied to the first diaphragm electrolytic unit E1 and a first current flows, the first current flows between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21, thereby transferring electrons (e) from the electrolytic cell anode 11 to the water (H2O) in the second aqueous solution L2 through the chloride ion supply tank cathode 21. - ) moves. Also, chloride ions (Cl) contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 move. - Chloride ions (Cl) are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by permeating through the anion exchange membrane 41. - ) is used in the reaction equation (b) in Figure 4 below. In other words, in the first aqueous solution L1, the electrons (e) before the first current flows (before the change) - ) After the first current flows (after the change), chloride ions (Cl - It can be said that this is the case.

[0096] Next, as shown in reaction equations (b) and (c) of Figure 4, two types of reactions occur at the electrolytic cell anode 11: chlorine (liquid) and oxygen (gas). • Reaction equation in Figure 4 (b): Anode 11 on the electrolytic cell side (chlorine generation reaction) Sodium chloride (NaCl) contained in the first aqueous solution L1, which is an aqueous sodium chloride solution, ionizes in water into sodium ions (Na + ) and chloride ions (Cl - ). Also, as described above in (a) of FIG. 4, chloride ions (Cl - ) are supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41. At the electrolytic cell side anode 11, the chloride ions (Cl - ) ionized in water and the chloride ions (Cl - ) supplied from the first aqueous solution L1 lose electrons (e - ), and chlorine (Cl2 (liquid, aq.)) is generated.

[0097] · Reaction formula (c) in FIG. 4: Electrolytic cell side anode 11 (oxygen generation reaction) At the electrolytic cell side anode 11, electrons (e - ) are taken away from the water (H2O) of the second aqueous solution L2, and oxygen (O2) and hydrogen ions (H + ) are generated.

[0098] · Reaction formula (d) in FIG. 4: In the first aqueous solution L1 (hypochlorous acid generation reaction) In the first aqueous solution L1 stored in the electrolytic cell 10, the chlorine (Cl2) generated in reaction formula (b) of FIG. 4 undergoes a hydrolysis reaction with the water (H2O) of the first aqueous solution L1, and hydrochloric acid (HCl) and hypochlorous acid (HClO) are generated. Hydrochloric acid (HCl) ionizes in an aqueous solution and exists as hydrogen ions (H + ) and chloride ions (Cl - ).

[0099] · Reaction formula (e) in FIG. 4: Hypochlorous acid generation reaction (equilibrium reaction formula) The equilibrium reaction formula of the hypochlorous acid generation reaction is shown. Depending on the increase or decrease of Cl - supplied from the second aqueous solution L2 to the first aqueous solution L1, the equilibrium state can shift to the right or to the left. Current control, which will be described later, is performed so that the Cl - contained in the first aqueous solution L1 stored in the electrolytic cell 10 does not apparently increase or decrease.

[0100] • Equation (f) in Figure 4: Equation for the change in chloride ions during electrolysis Equation (f) in Figure 4 represents the combined reaction equations (b) and (d) in Figure 4. The chlorine (Cl2) produced by reaction equation (b) in Figure 4 is converted into hydrochloric acid (HCl) and hypochlorous acid (HClO) according to reaction equation (d) in Figure 4.

[0101] Next, referring to Figures 4(g) to (i), we will explain the reactions that occur in the second aqueous solution L2 stored in the chloride ion supply tank 20.

[0102] <Chloride ion supply tank 20 (second aqueous solution L2)> • Figure 4(g): Anion exchange membrane 41 When a voltage is applied to the first diaphragm electrolytic unit E1 and the first current flows, chloride ions (Cl) contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 are released. - Chloride ions (Cl) are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by permeating through the anion exchange membrane 41. - ) is used in the reaction equation (b) of Figure 4 described above. Also, when the first current flows between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21, water (H2O) of the second aqueous solution L2 is released by electrons (e - ) is received. In other words, in the second aqueous solution L2, chloride ions (Cl) are present before the first current flows (before the change). - ) after the first current has flowed (after the change), electrons (e - It can be said that the water (H2O) in the second aqueous solution L2 becomes electrons (e - The reaction that occurs when ) is received is shown in the reaction equation (h) in Figure 4 below.

[0103] • Reaction equation (h) in Figure 4: Cathode 21 on the chloride ion supply tank side (hydrogen evolution reaction) At the chloride ion supply tank side cathode 21, water (H2O) in the second aqueous solution L2 is ionized (e - ) receives hydrogen (H2) and hydroxide ions (OH -Hydrogen is generated as a gas from the first outlet 23, and hydroxide ions are used in reaction equation (i) in Figure 4 below.

[0104] • Reaction equation (i) in Figure 4: Second aqueous solution L2 (magnesium hydroxide precipitation reaction) Magnesium ions (Mg) contained in the second aqueous solution L2, magnesium chloride 2+ ) and the hydroxide ions (OH) generated in the reaction equation (h) in Figure 4. - ) reacts with the other to form a precipitate of magnesium hydroxide (Mg(OH)2), which is a metal hydroxide precipitate.

[0105] Here, the solubility product of magnesium hydroxide (Mg(OH)2) is Ksp = 1.2 × 10⁻⁶. -11 (mol / L) 3 It is a substance that is extremely poorly soluble in aqueous solutions with a pH ranging from neutral to alkaline. For example, only 1.2 × 10⁻¹⁶ magnesium hydroxide is soluble in a weakly alkaline aqueous solution with a pH of 10. -3 The concentration is mol / L. In the second aqueous solution L2 of the chloride ion supply tank 20, hydroxide ions (OH) are generated by the reaction equation (g) in Figure 4. - ) is used to form a magnesium hydroxide precipitate, and hydroxide ions (OH) are produced in the second aqueous solution L2. - This suppresses the increase in the concentration of ) and the increase in the pH of the second aqueous solution L2.

[0106] Furthermore, when a magnesium chloride aqueous solution is used as the second aqueous solution L2, the pH of the saturated magnesium hydroxide aqueous solution produced after the first diaphragm electrolysis, where the magnesium hydroxide is saturated, is 10.36, calculated from the solubility product. Therefore, even after performing the first diaphragm electrolysis for a long period of time, the pH of the second aqueous solution L2 can be maintained at a weakly alkaline state of 10.36 or less. In other words, when a magnesium chloride aqueous solution is used as the second aqueous solution L2, it is possible to suppress the strong alkalinity of the second aqueous solution L2 stored in the chloride ion supply tank 20 after electrolysis, thereby providing a more safe air purification device 1.

[0107] Furthermore, for example, a contractor may install the air purification device 1 according to this embodiment. When the contractor removes the installed air purification device 1 after use, or during transportation after removal, the air purification device 1 may be overturned or dropped. In this case, if a magnesium chloride aqueous solution is used as the second aqueous solution L2, the second aqueous solution L2 after the electrolysis reaction is a weakly alkaline magnesium hydroxide aqueous solution. Therefore, even if the second aqueous solution L2 leaks outside the air purification device 1 due to overturning or dropping, safety can be further enhanced compared to an air purification device using a sodium chloride aqueous solution.

[0108] Next, referring to Figure 5, we will explain the chemical reactions that occur in the second diaphragm electrolytic section E2.

[0109] [Second diaphragm electrolytic section E2] In the second diaphragm electrolytic unit E2, reactions occur at both the chloride ion supply tank side cathode 21 and the metal ion supply tank side anode 51 via the anion exchange membrane 41 and the cation exchange membrane 42. That is, in the second diaphragm electrolytic unit E2, reactions occur at both the second aqueous solution L2 stored in the chloride ion supply tank 20 and the third aqueous solution L3 stored in the metal ion supply tank 50. The reaction in the second diaphragm electrolytic unit E2 supplies chloride ions from the second aqueous solution L2 to the first aqueous solution L1 stored in the electrolytic cell 10, and supplies metal ions from the third aqueous solution L3 to the first aqueous solution L1 stored in the electrolytic cell 10. For example, if the third aqueous solution L3 is a disodium hydrogen phosphate aqueous solution, sodium ions are supplied from the third aqueous solution L3 to the first aqueous solution L1.

[0110] The reaction in the second diaphragm electrolytic unit E2 supplies chloride ions from the second aqueous solution L2 to the first aqueous solution L1 stored in the electrolytic cell 10, causing a hypochlorous acid generation reaction in the first aqueous solution L1, as described later using reaction equation (d) in Figure 5. In other words, when the second diaphragm electrolytic unit E2 is used, chloride ions are supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 10 by both the first diaphragm electrolytic unit E1 and the second diaphragm electrolytic unit E2.

[0111] Figure 5 shows a list of chemical reactions occurring in the second aqueous solution L2 stored in the chloride ion supply tank 20 of the second diaphragm electrolytic unit E2, and in the third aqueous solution L3 stored in the metal ion supply tank 50.

[0112] When a predetermined voltage is applied to the second diaphragm electrolytic unit E2, a second current flows, electrons move, and the chemical reaction shown in Figure 5 occurs. First, referring to Figures 5(a) to (c), the chemical reaction that occurs in the second aqueous solution L2 stored in the chloride ion supply tank 20 will be explained. Note that the chemical reaction that occurs in the second aqueous solution L2 stored in the chloride ion supply tank 20 shown in Figures 5(a) to (c) is substantially the same as the chemical reaction explained using Figures 4(g) to (i).

[0113] <Chloride ion supply tank 20 (second aqueous solution L2)> Figure 5(a): Anion exchange membrane 41 When a voltage is applied to the second diaphragm electrolytic unit E2 and a second current flows, chloride ions (Cl) contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 are released. - Chloride ions (Cl) are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by permeating through the anion exchange membrane 41. - ) is used in the reaction equation (b) of Figure 5 described above. Also, when a second current flows between the chloride ion supply tank side cathode 21 and the metal ion supply tank side anode 51, water (H2O) of the second aqueous solution L2 is released from the metal ion supply tank side anode 51 through the chloride ion supply tank side cathode 21 by electrons (e -) is received. In other words, in the second aqueous solution L2, chloride ions (Cl) are present before the first current flows (before the change). - ) after the first current has flowed (after the change), electrons (e - It can be said that the water (H2O) in the second aqueous solution L2 becomes electrons (e - The reaction that occurs when ) is received is shown in the reaction equation (b) in Figure 5 below.

[0114] • Reaction equation in Figure 5 (b): Cathode 21 on the chloride ion supply tank side (hydrogen evolution reaction) At the chloride ion supply tank side cathode 21, water (H2O) in the second aqueous solution L2 is ionized (e - ) receives hydrogen (H2) and hydroxide ions (OH - Hydrogen is generated as a gas from the first outlet 23, and hydroxide ions are used in the reaction equation (c) in Figure 5 below.

[0115] • Reaction equation (c) in Figure 5: Second aqueous solution L2 (magnesium hydroxide precipitation reaction) Magnesium ions (Mg) contained in the second aqueous solution L2, magnesium chloride 2+ ) and the hydroxide ions (OH) generated in reaction equation (b) of Figure 6. - ) reacts with the other to form a precipitate of magnesium hydroxide (Mg(OH)2), which is a metal hydroxide precipitate.

[0116] Next, referring to Figures 5(d) to (e), we will explain the reactions that occur in the third aqueous solution L3 stored in the metal ion supply tank 50.

[0117] <Metal ion supply tank 50 (third aqueous solution L3)> • Reaction equation (d) in Figure 5: Anode 51 on the metal ion supply tank side (oxygen evolution reaction) At the anode 51 on the metal ion supply tank side, electrons (e) are released from water (H2O) in the third aqueous solution L3. - ) is removed, and oxygen (O2) and hydrogen ions (H + ) is generated. Oxygen volatilizes as a gas from the second outlet 53.

[0118] • Figure 5(e) Cation exchange membrane 42 When a voltage is applied to the second diaphragm electrolytic unit E2 and a second current flows, sodium ions (Na) contained in the third aqueous solution L3, which is a disodium hydrogen phosphate aqueous solution, stored in the metal ion supply tank 50 are released. + ) are supplied to the first aqueous solution L1 by permeating the cation exchange membrane 42. In addition, a second current flows between the chloride ion supply tank side cathode 21 and the metal ion supply tank side anode 51, causing the electrons (e) generated in reaction equation (d) in Figure 5 to be supplied. - ) move from the anode 51 on the metal ion supply tank side to the cathode 21 on the chloride ion supply tank side to the second aqueous solution L2. In other words, sodium ions (Na) that were present in the third aqueous solution L3 before the second current flowed (before the change) move. + ) and electrons (e - It can be said that after the second current flows (after the change), the electrons (e - The reaction that occurs upon receiving ) is as explained using reaction equation (b) in Figure 5.

[0119] Next, referring to Figure 6, the chemical reactions occurring in the diaphragm-free electrolytic section E3 will be explained. In the diaphragm-free electrolytic section E3, reactions occur in the first aqueous solution L1 stored in the electrolytic cell 10 at both the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 without the ion exchange membrane. In other words, in the diaphragm-free electrolytic section E3, reactions occur only in the first aqueous solution L1 stored in the electrolytic cell 10.

[0120] [Diaphragmless electrolysis section E3 (electrolytic cell 10)] Figure 6 shows the first aqueous solution L1 stored in the electrolytic cell 10 of the diaphragm-free electrolytic unit E3. This is a list of reaction equations. When a predetermined voltage is applied to the diaphragm-free electrolytic section E3, a third current flows, electrons move, and the chemical reactions shown in reaction equations (a) to (g) in Figure 6 occur.

[0121] Before explaining the diaphragm-free electrolytic section E3, let's first describe the changes. First, chloride ions from the second aqueous solution L2 and sodium ions and electrons from the third aqueous solution L3 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10.

[0122] Figure 6(a): Anion exchange membrane 41 As described above, when a voltage is applied to the first diaphragm electrolytic unit E1 and the second diaphragm electrolytic unit E2, and the first current and the second current flow, the first aqueous solution L1 stored in the electrolytic cell 10 reacts and produces electrons (e - ) loses electrons (e - In the first aqueous solution L1, which has lost its charge, a force acts to maintain electrical neutrality, and negatively charged chloride ions (Cl) are present. - ) are supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 through the anion exchange membrane 41 to the first aqueous solution L1 stored in the electrolytic cell 10. In the first aqueous solution L1, electrons (e) before the change - ) changes and then chloride ions (Cl - It can be said that this is the case.

[0123] Next, as shown in reaction equation (b) in Figure 6 and reaction equation (c) in Figure 4, two types of reactions occur at the electrolytic cell anode 11: chlorine (liquid) and oxygen (gas).

[0124] • Reaction equation (b) in Figure 6: Anode 11 on the electrolytic cell side (chlorine generation reaction) The sodium chloride (NaCl) contained in the first aqueous solution L1, a sodium chloride aqueous solution, is converted into sodium ions (Na) in water. + ) and chloride ions (Cl - It ionizes into (Cl). Also, as described above in Figure 6(a), chloride ions (Cl) are transferred from the second aqueous solution L2 to the first aqueous solution L1 via the anion exchange membrane 41. - ) is supplied. At the electrolytic cell anode 11, chloride ions (Cl) ionized in water are supplied. - ) and chloride ions (Cl) supplied from the first aqueous solution L1 - ) is an electron (e - It loses its ions and generates chlorine (Cl2 (liquid, aq.)).

[0125] • Reaction equation (c) in Figure 6: Anode 11 on the electrolytic cell side (oxygen evolution reaction) At the electrolytic cell anode 11, electrons (e) are released from water (H2O) in the first aqueous solution L1. -) is removed, and oxygen (O2) and hydrogen ions (H + ) occurs.

[0126] • Figure 6(d) Cation exchange membrane 42 When a voltage is applied to the second diaphragm electrolytic unit E2 and a second current flows, sodium ions (Na) present in the third aqueous solution L3 are transferred through the cation exchange membrane 42. + ) and electrons (e - ) are supplied to the first aqueous solution L1. In other words, before the second current flows (before the change), there are no sodium ions and electrons in the first aqueous solution L1 originating from the third aqueous solution L3, but after the second current flows (after the change), sodium ions and electrons are supplied from the third aqueous solution L3 to the first aqueous solution L1 via the cation exchange membrane 42.

[0127] • Reaction equation (e) in Figure 6: Electrolytic cell side cathode 12 (hydrogen evolution reaction) At the electrolytic cell cathode 12, water (H2O) in the first aqueous solution L1 is converted into electrons (e - ) receives hydrogen (H2) and hydroxide ions (OH - ) occurs.

[0128] • Reaction equation (f) in Figure 6: Hypochlorous acid generation reaction in the first aqueous solution L1 In the first aqueous solution L1 stored in the electrolytic cell 10, the chlorine (Cl2) generated in reaction equation (b) of Figure 6 undergoes a hydrolysis reaction with water (H2O) in the first aqueous solution L1, generating hydrochloric acid (HCl) and hypochlorous acid (HClO). Hydrochloric acid (HCl) dissociates in aqueous solution to form hydrogen ions (H+) and chloride ions (ClO). - It exists as (H). In addition, hydrogen ions generated in reaction equation (c) in Figure 6 are present in the first aqueous solution L1. + ) is the hydroxide ion (OH) generated in reaction equation (e) in Figure 6. - It reacts with ) to form water. In other words, the first aqueous solution The generation of hydrogen ions in liquid L1 may cause a decrease in the pH of the first aqueous solution L1, but the hydrogen ions (H + ) and hydroxide ions (OH) generated at the electrolytic cell cathode 12 -The reaction between ) and can suppress the decrease in pH of the first aqueous solution L1 that occurs with an increase in hydrogen ions.

[0129] • Reaction equation (g) in Figure 6: Hypochlorous acid generation reaction (equilibrium reaction equation) The equilibrium reaction equation for the hypochlorous acid generation reaction is shown. Cl supplied from the second aqueous solution L2 to the first aqueous solution L1. - Depending on the increase or decrease of Cl in the electrolytic cell 10, the equilibrium state may shift to the right or to the left. - To prevent the apparent increase or decrease, current control is performed as described later.

[0130] • Equation (h) in Figure 6: Equation for the change in chloride ions during electrolysis Equation (h) in Figure 6 represents the combined reaction equations (b) and (f) in Figure 6. The chlorine (Cl2) produced by reaction equation (b) in Figure 6 is converted into hydrochloric acid (HCl) and hypochlorous acid (HClO) according to reaction equation (f) in Figure 6.

[0131] The current control unit 60 controls the above chemical reaction by controlling electrolysis. In this case, bubbling of the first aqueous solution L1 during the purification operation of the air purification device 1 can cause the sodium chloride aqueous solution contained in the first aqueous solution L1 to splash and adhere to the inner wall surface of the electrolytic cell 10 located in the internal space 15 on the electrolytic cell side. When only the water evaporates from these droplets, the sodium chloride remaining on the inner wall surface of the electrolytic cell 10 crystallizes and turns white, which is known as salt splashing. Salt splashing also includes the splashing of the sodium chloride aqueous solution into the room space R as droplets along with the mixed air M released from the outlet 17. Therefore, in the electrolytic cell 10, (1) a decrease in chloride ions due to diaphragm-free electrolysis in the diaphragm-free electrolysis section E3 and (2) a decrease in chloride ions and sodium ions due to salt splashing can occur.

[0132] The current control by the current control unit 60 will be described below.

[0133] The current control unit 60 (1) controls the first current to supply chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by passing them through the anion exchange membrane 41, in order to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by diaphragmless electrolysis in the diaphragmless electrolysis unit E3. Furthermore, if the first aqueous solution L1 is a sodium chloride aqueous solution, the current control unit 60 (2) controls the second current of the second diaphragm electrolysis unit E2 to supply chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by passing them through the anion exchange membrane 41, in order to replenish the chloride ions and sodium ions contained in the first aqueous solution L1 that have been reduced by salt evaporation, in order to supply chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1, and also supplies sodium ions contained in the third aqueous solution L3 to the first aqueous solution L1.

[0134] The current control unit 60 supplies the chloride ions and sodium ions that have decreased in the first aqueous solution L1, and flows the first current, second current, and third current in predetermined proportions so that the hypochlorous acid concentration of the first aqueous solution L1 is maintained at a predetermined concentration.

[0135] The following provides a more detailed explanation of the current control for each current. The third current of the non-diaphragm electrolysis unit E3 is set according to the desired amount of hypochlorous acid gas generated. The first current (first diaphragm electrolysis) is controlled to compensate for the chloride ions contained in the first aqueous solution L1 that have been reduced by the purification operation. The ratio of the first current to the third current (non-diaphragm electrolysis) is fixed at a constant level within a predetermined range, and the ratios of both the first and third currents are changed. More specifically, when the third current is 150 mA, the first current is 5 mA. In this way, chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 by permeating the anion exchange membrane 41, in order to compensate for the chloride ions contained in the first aqueous solution L1 that have been reduced by non-diaphragm electrolysis.

[0136] If the first aqueous solution L1 is a sodium chloride aqueous solution, the second current of the second diaphragm electrolytic unit E2 is controlled to replenish the chloride ions and sodium ions contained in the first aqueous solution L1 that have decreased due to salt evaporation. The second current may, for example, be stopped under normal conditions. If the second current is stopped, information regarding the decrease in chloride ions and sodium ions and the time of the purification operation is determined in advance through experiments, etc., and when the decrease in chloride ions and sodium ions reaches the specified values, the stop of the second current is released and the second current is turned on. In this way, chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 by permeating the anion exchange membrane 41, and sodium ions contained in the third aqueous solution L3 are supplied to the first aqueous solution L1 by permeating the cation exchange membrane 42, in order to replenish the chloride ions and sodium ions contained in the first aqueous solution L1 that have decreased due to salt evaporation.

[0137] As described above, the current control unit 60 supplies the necessary amount of chloride ions to the first aqueous solution L1 stored in the electrolytic cell 10 by applying a first current in accordance with the desired amount of hypochlorous acid gas generated, and by applying second and third currents to compensate for the decreased chloride ions and sodium ions, thereby maintaining the hypochlorous acid concentration of the first aqueous solution L1 at a predetermined concentration.

[0138] As described above, the chloride ions and sodium ions consumed by the first aqueous solution L1 can be appropriately supplied from the second aqueous solution L2 and the third aqueous solution L3, respectively, thus providing a space purification device 1 capable of stably generating a desired amount of hypochlorous acid gas. Therefore, a space purification device 1 can be provided that can stably generate a desired amount of hypochlorous acid gas without supplying an aqueous solution containing chloride ions from an external source for a long period of time, such as one year.

[0139] Alternatively, multiple current control units 60 may be provided to control the first current, second current, and third current separately.

[0140] Furthermore, when diaphragm-free electrolysis is performed in an electrolytic cell at room temperature and atmospheric pressure, the electrolyte of the first aqueous solution L1 should be an electrically conductive electrolyte that is not used in electrolysis, does not generate mainly oxygen and chlorine from the anode, does not cause a decrease in the concentration of hypochlorous acid by reacting with hypochlorous acid, and does not react with each electrode, electrolytic cell, and anion exchange membrane. More specifically, in addition to the first aqueous solution L1 described above, other solutions may include, for example, metal chloride aqueous solutions, hydroxide salt aqueous solutions, acidic salt aqueous solutions, phosphate aqueous solutions, or combinations thereof. As a metal chloride aqueous solution, for example, a dilute calcium chloride aqueous solution or a dilute magnesium chloride aqueous solution may be used. As a hydroxide salt aqueous solution, for example, a dilute sodium hydroxide aqueous solution or a dilute potassium hydroxide aqueous solution of 0.4% by weight (0.1 mol / L) or less may be used. As an acidic salt aqueous solution, for example, a dilute hydrochloric acid aqueous solution of 0.4% by weight (0.1 mol / L) or less may be used. As a phosphate aqueous solution, for example, a disodium hydrogen phosphate aqueous solution, a sodium dihydrogen phosphate aqueous solution, a dipotassium hydrogen phosphate aqueous solution, or a potassium dihydrogen phosphate aqueous solution may be used. As a specific example of the combination of the second aqueous solution L2, pH adjustment may be performed by combining a dilute sodium chloride aqueous solution and a dilute sodium hydroxide aqueous solution.

[0141] [Supplying operation of high-concentration chloride aqueous solution (HC)] The following explains the definitions of terms used in describing the supply operation of the high-concentration chloride aqueous solution HC, and the supply operation of the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 to the chloride ion supply tank 20 during (1) purification operation, (2) when the purification operation is stopped (second state P2), (3) when the purification operation is restarted, and (4) when the purification operation is stopped (first state P1) of the air purification device 1.

[0142] [Definition of Terms] In this specification, the first state P1, the second state P2, the reference threshold V0, the first threshold V1 and The terms and the second threshold V2 will be used in the explanation. Furthermore, the concentration of chloride ions in each tank (electrolytic cell 10, chloride ion supply tank 20) ​​will be assumed to correspond to the ion concentration of the aqueous solution in each tank.

[0143] The first state P1 is a state in which the concentration of chloride ions in the second aqueous solution L2 in the chloride ion supply tank 20 is higher than the concentration of chloride ions in the first aqueous solution L1 in the electrolytic cell 10.

[0144] The second state P2 is a state in which the concentration of chloride ions in the second aqueous solution L2 in the chloride ion supply tank 20 is lower than the concentration of chloride ions in the first aqueous solution L1 in the electrolytic cell 10.

[0145] The reference threshold V0 is a second voltage value obtained when the concentration of chloride ions in the second aqueous solution L2 is the same as the concentration of chloride ions in the first aqueous solution L1. The reference threshold V0 is, for example, the initial chloride ion concentration of the first aqueous solution L1 and the initial chloride ion concentration of the second aqueous solution L2, and more specifically, it is the second voltage value obtained by the voltage acquisition unit 60a at a concentration of 50 g / L (a mass percentage concentration of 5% in the dilute sodium chloride aqueous solution), and this second voltage value is set as the threshold.

[0146] The first threshold value V1 is defined as the lower limit of the second voltage value acquired by the voltage acquisition unit 60a in the first state P1. The first threshold value V1 is, for example, the second voltage value acquired when the chloride ion concentration of the second aqueous solution L2 becomes 60 g / L (the mass percentage concentration of the dilute sodium chloride aqueous solution is 6%), and this second voltage value is set as the threshold value.

[0147] The second threshold V2 is defined as the upper limit of the second voltage value acquired by the voltage acquisition unit 60a in the second state P2. The second threshold V2 is, for example, the second voltage value acquired when the chloride ion concentration of the second aqueous solution L2 becomes 10 g / L (the mass percentage concentration of the dilute sodium chloride aqueous solution is 1%), and this second voltage value is set as the threshold.

[0148] (1) Supply operation of high-concentration chloride aqueous solution HC during purification operation Next, referring to Figure 7, the supply operation of supplying the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 to the second aqueous solution L2 in the chloride ion supply tank 20 during the purification operation will be explained in more detail. Figure 7 is a diagram showing the change in chloride ion concentration of the second aqueous solution L2 over time during the purification operation. In the figure, the horizontal axis represents time, the vertical axis on the left represents the chloride ion concentration of the second aqueous solution L2, and the vertical axis on the right represents the second voltage value applied between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21.

[0149] First, let's explain the state immediately after the high-concentration chloride solution HC is supplied to the second aqueous solution L2. As shown in the graph in Figure 7 (thick black line), during the purification operation, the high-concentration chloride solution HC is supplied to the second aqueous solution L2 so that the chloride ion concentration in the second aqueous solution L2 becomes the same as the chloride ion concentration in the first aqueous solution L1. In other words, at time t0 immediately after the high-concentration chloride solution HC is supplied to the second aqueous solution L2, the concentration of chloride ions contained in the second aqueous solution L2 is the same as the concentration of chloride ions contained in the first aqueous solution L1. Then, the air purification device 1 starts the purification operation. Accordingly, the voltage acquisition unit 60a acquires the first voltage value applied between the electrolytic cell side anode 11 and the electrolytic cell side cathode 12, and the second voltage value applied between the electrolytic cell side anode 11 and the chloride ion supply tank side cathode 21. The storage unit 60d stores the first voltage value and the second voltage value acquired by the voltage acquisition unit 60a during the purification operation.

[0150] The air purification device 1 performs a purification operation using a second aqueous solution L2 with the same concentration of chloride ions and a second state P2. Consequently, the chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by the first diaphragm electrolysis, and thus decrease. As a result, the concentration of chloride ions in the second aqueous solution L2 becomes lower. In other words, the second voltage value acquired by the voltage acquisition unit 60a increases. Then, at time t1, when the second voltage value acquired by the voltage acquisition unit 60a reaches the second threshold V2, the supply of high-concentration chloride aqueous solution HC by the delivery unit 31 is started.

[0151] When the supply of the high-concentration chloride aqueous solution HC by the supply unit 31 begins, the concentration of chloride ions in the second aqueous solution L2 rapidly increases, and the second voltage value decreases. Then, at time t2, when the second voltage value acquired by the voltage acquisition unit 60a reaches the reference threshold V0, the supply of the high-concentration chloride aqueous solution HC by the supply unit 31 is stopped. As a result, at time t2, the second aqueous solution L2 is in the same state as at time t0, that is, the concentration of chloride ions in the second aqueous solution L2 is the same as the concentration of chloride ions in the first aqueous solution L1.

[0152] The air purification device 1 then continues its purification operation. Then, from time t2 onward, that is, at times t3 and t4, the second voltage value acquired by the voltage acquisition unit 60a and the chloride ion concentration of the second aqueous solution L2 change, following the same time progression as at times t1 and t2, respectively. Although not specifically shown in the diagram, the same cycle is repeated from time t4 onward.

[0153] As described above, the air purification device 1 is put into operation. During the purification operation, the first aqueous solution L1 is electrolyzed and air containing hypochlorous acid is released into the indoor space R. During the purification operation, chloride ions consumed by the first aqueous solution L1 are supplied as needed from the second aqueous solution L2, and chloride ions consumed by the second aqueous solution L2 are supplied as needed from the high-concentration chloride aqueous solution HC, so that the desired amount of hypochlorous acid gas can be generated stably.

[0154] (2) Supply operation of high-concentration chloride aqueous solution HC when the purification operation is stopped in the second state P2 In this embodiment, "stopping the purification operation" means stopping the release of hypochlorous acid into the indoor space R by performing the purification operation stop procedure. That is, it means stopping at least the non-diaphragm electrolysis among the non-diaphragm electrolysis, the first diaphragm electrolysis, and the second diaphragm electrolysis. Furthermore, it means stopping the supply of air to the electrolytic cell 10 via the blower pipe 14 by the air supply unit 13 along with stopping the non-diaphragm electrolysis. Thus, in this embodiment, "stopping the purification operation" means putting the space purification device 1 into a standby state so that the purification operation can be immediately resumed, and does not mean turning off the power to the space purification device 1 and completely shutting down the device. Note that the supply of air to the electrolytic cell 10 by the air supply unit 13 may be stopped after the purification operation stop procedure has been performed and at least the non-diaphragm electrolysis has been stopped, and the supply of air to the electrolytic cell 10 by the air supply unit 13 has been continued for a predetermined time.

[0155] In this embodiment, by performing the purification operation stop procedure, at least the non-diaphragm electrolysis and the supply of air to the electrolytic cell 10 by the air supply unit 13 are stopped, and the purification operation is stopped. After the purification operation is stopped, control is performed to make the chloride ion concentration of the second aqueous solution L2 higher than the chloride ion concentration of the first aqueous solution L1. This control will be described later.

[0156] Furthermore, as mentioned above, since the air purification device 1 is intended for use for 8 hours a day, the "suspension of purification operation" period in this embodiment is assumed to be 16 hours.

[0157] As described above, the anion exchange membrane 41, which is placed between the electrolytic cell 10 and the chloride ion supply tank 20, allows chloride ions to pass through based on the voltage applied between the electrolytic cell-side anode 11 of the electrolytic cell 10 and the chloride ion supply tank-side cathode 21 of the chloride ion supply tank 20. However, the chloride ion concentration of the first aqueous solution L1 stored in the electrolytic cell 10 and the chloride ion supply tank 20 If there is a concentration difference between the chloride ion concentration of the first aqueous solution L1 and the second aqueous solution L2 stored in the anion exchange membrane 41, osmotic pressure will be generated, and water from either the first aqueous solution L1 or the second aqueous solution L2 may move across the anion exchange membrane 41 in a direction that eliminates the concentration difference. In other words, in order to eliminate the concentration difference, water may move from the side with the lower chloride ion concentration to the side with the higher chloride ion concentration among the first aqueous solution L1 and the second aqueous solution L2.

[0158] Here, if the chloride ion concentration of the second aqueous solution L2 in the chloride ion supply tank 20 is lower than the chloride ion concentration of the first aqueous solution L1 in the electrolytic cell 10, that is, if there is a concentration difference, the purification operation may be stopped, and water may move from the second aqueous solution L2 to the first aqueous solution L1. More specifically, while the purification operation is stopped, no chloride ions are supplied from the chloride ion supply tank 20 to the first aqueous solution L1, so the absolute amount of chloride ions contained in the first aqueous solution L1 does not change. However, if water moves from the second aqueous solution L2 to the first aqueous solution L1 via the anion exchange membrane 41 due to osmotic pressure, the amount of water in the first aqueous solution L1 will increase. Therefore, the increase in the amount of water in the first aqueous solution L1 that may occur while the purification operation is stopped may cause the chloride ion concentration of the first aqueous solution L1 to decrease. During the purification operation, the hypochlorous acid concentration in the first aqueous solution L1 is maintained at a predetermined level. However, if the purification operation is restarted after stopping, when the chloride ion concentration in the first aqueous solution L1 is lower than the predetermined level, the amount of hypochlorous acid gas generated may decrease. Consequently, it may become difficult to stably generate the desired amount of hypochlorous acid gas.

[0159] Therefore, in this embodiment, in order to prevent the amount of water in the first aqueous solution L1 from increasing while the purification operation is stopped, the chloride ion concentration of the first aqueous solution L1 from decreasing, and thus the amount of hypochlorous acid gas generated when the purification operation is restarted from decreasing, the purification operation is stopped when the chloride ion concentration of the second aqueous solution L2 is higher than the chloride ion concentration of the first aqueous solution L1.

[0160] Specifically, the estimation unit 60c of the current control unit 60 estimates the chloride ion concentration of the second aqueous solution L2 relative to the chloride ion concentration of the first aqueous solution L1, based on the first voltage value obtained by the voltage acquisition unit 60a during non-diaphragm electrolysis and the second voltage value obtained during the first diaphragm electrolysis. If the purification operation is stopped when the estimated chloride ion concentration of the second aqueous solution L2 is lower than that of the first aqueous solution L1, the delivery unit 31 supplies a high-concentration chloride aqueous solution HC to the second aqueous solution L2 so that the chloride ion concentration of the second aqueous solution L2 becomes higher than that of the first aqueous solution L1.

[0161] By stopping the purification operation when the chloride ion concentration in the second aqueous solution L2 is higher than that of the first aqueous solution L1, water moves from the first aqueous solution L1 to the second aqueous solution L2 via the anion exchange membrane 41 while the purification operation is stopped. Since no chloride ions are supplied from the chloride ion supply tank 20 to the first aqueous solution L1 while the purification operation is stopped, the absolute amount of chloride ions contained in the first aqueous solution L1 does not change. That is, when the purification operation is stopped, the concentration of the first aqueous solution L1 is a predetermined concentration, so the absolute amount of chloride ions contained in the first aqueous solution L1 is the amount corresponding to the predetermined concentration required to generate the desired amount of hypochlorous acid gas. However, if water moves from the first aqueous solution L1 to the second aqueous solution L2 via the anion exchange membrane 41 due to osmotic pressure, the amount of water in the first aqueous solution L1 decreases. As a result of the decrease in water in the first aqueous solution L1 that may occur while the purification operation is stopped, the chloride ion concentration of the first aqueous solution L1 increases (becomes more concentrated) compared to the predetermined concentration. Therefore, after stopping the purification operation, the purification operation can be restarted with the chloride ion concentration of the first aqueous solution L1 higher than a predetermined concentration, and in particular, the decrease in the amount of hypochlorous acid gas generated when the purification operation is restarted can be suppressed.

[0162] Furthermore, the volume of the electrolytic cell 10 is smaller than the volume of the chloride ion supply tank 20. That is, the volume of the first aqueous solution L1 is smaller than the volume of the second aqueous solution L2. Furthermore, if the chloride ion concentration of the first aqueous solution L1 is higher than that of the second aqueous solution L2, and water moves from the second aqueous solution L2 to the first aqueous solution L1, a large amount of water will move to eliminate the concentration difference. If the purification operation is stopped for a long period of time, and water moves from the second aqueous solution L2 to the first aqueous solution L1 due to osmotic pressure, the amount of water in the first aqueous solution L1 will increase, and the amount of liquid in the first aqueous solution L1 may exceed the amount of liquid that can be stored in the electrolytic cell 10, potentially causing the first aqueous solution L1 to overflow from the electrolytic cell 10.

[0163] In contrast, as in this embodiment, if the chloride ion concentration of the second aqueous solution L2 is higher than that of the first aqueous solution L1, and water moves from the first aqueous solution L1 to the second aqueous solution L2 to eliminate the concentration difference, the chloride ion concentration of the first aqueous solution L1 will increase with the movement of a small amount of water, and the concentration difference between the first aqueous solution L1 and the second aqueous solution L2 will be eliminated. Therefore, even if the purification operation is stopped for a long period of time, it is possible to prevent the first aqueous solution L1 from overflowing from the electrolytic cell 10.

[0164] Next, referring to Figure 8, we will explain in more detail the supply operation in which the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 in the chloride ion supply tank 20 when the purification operation is stopped in the second state P2. Figure 8 is a diagram showing the change in chloride ion concentration of the second aqueous solution L2 over time when the purification operation is stopped and when the purification operation is restarted. In the figure, the horizontal axis represents time, the vertical axis on the left represents the chloride ion concentration of the second aqueous solution L2, and the vertical axis on the right represents the second voltage value applied between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21.

[0165] First, let's explain the state in which the purification operation is being performed using the second aqueous solution L2 in the second state P2. As shown in the graph in Figure 8 (thick black line), in the purification operation using the second aqueous solution L2 in the second state P2, the concentration of chloride ions in the second aqueous solution L2 decreases from the same concentration as the concentration of chloride ions in the first aqueous solution L1. In other words, the second voltage value acquired by the voltage acquisition unit 60a increases from the reference threshold V0 towards the second threshold V2. As the air purification device 1 is being purified, the voltage acquisition unit 60a acquires the first voltage value applied between the electrolytic cell anode 11 and the electrolytic cell cathode 12, and the second voltage value applied between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21, respectively. The storage unit 60d stores the first and second voltage values ​​acquired by the voltage acquisition unit 60a during the purification operation.

[0166] Therefore, at time t11, the purification operation is stopped. The calculation unit 60b and the estimation unit 60c estimate the chloride ion concentration of the first aqueous solution L1, the chloride ion concentration of the second aqueous solution L2, and the state of the chloride ion concentration of the second aqueous solution L2 (first state P1 or second state P2) based on the first voltage value and second voltage value stored by the storage unit 60d immediately before the stop operation.

[0167] At this time, if the concentration of chloride ions in the second aqueous solution L2 is lower than the concentration of chloride ions in the first aqueous solution L1 (second state P2), the supply of high-concentration chloride aqueous solution HC by the delivery unit 31 is started so that the concentration of chloride ions in the second aqueous solution L2 becomes higher than the concentration of chloride ions in the first aqueous solution L1 (first state P1). In other words, if the purification operation is stopped when the second voltage value exceeds the reference threshold V0, high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 so that the second voltage value falls below the reference threshold V0.

[0168] Specifically, the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 such that the second voltage value acquired by the voltage acquisition unit 60a becomes a first threshold V1 (more preferably less than or equal to the first threshold V1) which is set to be less than the reference threshold V0. At this time, the amount of high-concentration chloride aqueous solution HC to be supplied is calculated by the calculation unit 60b based on the concentration of chloride ions contained in the second aqueous solution L2. Specifically, the amount of high-concentration chloride aqueous solution HC to be supplied is calculated by the calculation unit 60b, The second voltage value acquired by the voltage acquisition unit 60a when the purification operation is stopped is calculated and identified based on the first threshold value V1.

[0169] Immediately after the purification operation is stopped, the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 begins, and the concentration of chloride ions in the second aqueous solution L2 increases rapidly. Then, at time t12, when the second voltage value acquired by the voltage acquisition unit 60a reaches the first threshold V1 (when the supply of the amount of high-concentration chloride aqueous solution HC calculated by the calculation unit 60b is completed), the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 is stopped.

[0170] As described above, the purification operation of the air purification device 1 is stopped. If the purification operation is stopped when the chloride ion concentration of the second aqueous solution L2 is lower than that of the first aqueous solution L1 (second state P2), chloride ions are supplied from the high-concentration chloride aqueous solution HC to the second aqueous solution L2. In other words, the purification operation is controlled to stop when the chloride ion concentration of the second aqueous solution L2 is higher than that of the first aqueous solution L1. Therefore, even immediately after restarting the purification operation, the desired amount of hypochlorous acid gas can be stably generated.

[0171] (3) Supply operation of high-concentration chloride aqueous solution HC when resuming the purification operation Next, referring to Figure 8, we will explain in more detail the supply operation in which the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 of the chloride ion supply tank 20 when the purification operation is restarted.

[0172] First, let's explain the state immediately after the purification operation is restarted. In this embodiment, by performing the purification operation start procedure, the stopped electrolysis (at least non-diaphragm electrolysis) and the supply of air to the electrolytic cell 10 by the air supply unit 13 are restarted, and the purification operation is started. As shown in the graph of Figure 8 (thick black line), at time t13 immediately after the purification operation is restarted, the concentration of chloride ions in the second aqueous solution L2 is higher than the concentration of chloride ions in the first aqueous solution L1, which is the first state P1. Then, the air purification device 1 starts the purification operation. Accordingly, the voltage acquisition unit 60a acquires a first voltage value applied between the electrolytic cell side anode 11 and the electrolytic cell side cathode 12 and a second voltage value applied between the electrolytic cell side anode 11 and the chloride ion supply tank side cathode 21. The storage unit 60d stores the first voltage value and the second voltage value acquired by the voltage acquisition unit 60a during the purification operation.

[0173] The air purification device 1 first performs a purification operation using the second aqueous solution L2 in the first state P1. As a result, the chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by the first diaphragm electrolysis, and thus decrease. Consequently, the concentration of chloride ions contained in the second aqueous solution L2 becomes lower. In other words, the second voltage value acquired by the voltage acquisition unit 60a increases. Then, at time t14, the second voltage value acquired by the voltage acquisition unit 60a becomes the reference threshold V0. That is, at time t14, the concentration of chloride ions contained in the second aqueous solution L2 is the same as the concentration of chloride ions contained in the first aqueous solution L1.

[0174] The air purification device 1 then performs a purification operation using the second aqueous solution L2, which has the same concentration of chloride ions and is in the second state P2. As a result, the concentration of chloride ions in the second aqueous solution L2 decreases further, and the second voltage value acquired by the voltage acquisition unit 60a increases further. Then, at time t15, when the second voltage value acquired by the voltage acquisition unit 60a reaches the second threshold V2, the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 is started.

[0175] When the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 begins, the concentration of chloride ions in the second aqueous solution L2 increases rapidly, and the second voltage value acquired by the voltage acquisition unit 60a decreases. Then, at time t16, the second voltage value acquired by the voltage acquisition unit 60a When the reference threshold V0 is reached, the supply of the high-concentration chloride aqueous solution HC by the dispensing unit 31 is stopped. As a result, at time t16, the second aqueous solution L2 is in the same state as at time t14, that is, the concentration of chloride ions in the second aqueous solution L2 is the same as the concentration of chloride ions in the first aqueous solution L1.

[0176] The air purification device 1 then continues its purification operation in that concentration state. After time t16, although not specifically shown in the diagram, the second voltage value acquired by the voltage acquisition unit 60a and the chloride ion concentration of the second aqueous solution L2 change in the same way as at times t14 and t15, and the same cycle is repeated.

[0177] (4) Supply operation of high-concentration chloride aqueous solution HC when the purification operation is stopped in the first state P1 Next, we will explain the supply operation in which the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 in the chloride ion supply tank 20 when the purification operation is stopped in the first state P1.

[0178] First, let's explain the state after the purification operation has resumed. After the purification operation has resumed, the purification operation is performed using the second aqueous solution L2 in the first state P1. At this time, the concentration of chloride ions in the second aqueous solution L2 decreases from a state in which it is higher than the concentration of chloride ions in the first aqueous solution L1. In other words, the second voltage value acquired by the voltage acquisition unit 60a increases from the first threshold V1 toward the reference threshold V0. That is, after the purification operation has resumed, the purification operation will remain in the first state P1 until a certain period of time has elapsed.

[0179] During the purification operation, the air purification device 1's voltage acquisition unit 60a acquires a first voltage value applied between the electrolytic cell anode 11 and the electrolytic cell cathode 12, and a second voltage value applied between the electrolytic cell anode 11 and the chloride ion supply tank cathode 21. The storage unit 60d stores the first and second voltage values ​​acquired by the voltage acquisition unit 60a during the purification operation.

[0180] Therefore, at any time during the purification operation using the second aqueous solution L2 in the first state P1, the purification operation is stopped. When the purification operation is stopped, the calculation unit 60b and the estimation unit 60c re-estimate the chloride ion concentration of the second aqueous solution L2 and the state of the chloride ion concentration of the second aqueous solution L2 (first state P1 or second state P2) based on the first voltage value and second voltage value stored in the storage unit 60d immediately before the stop operation.

[0181] At this time, if the concentration of chloride ions in the second aqueous solution L2 is higher than the concentration of chloride ions in the first aqueous solution L1 (a first state P1), a high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 so that the second voltage value acquired by the voltage acquisition unit 60a becomes the first threshold V1 (the first threshold V1 is a value smaller than the reference threshold V0).

[0182] In this embodiment, a high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 such that the second voltage value acquired by the voltage acquisition unit 60a becomes the first threshold V1. The amount of high-concentration chloride aqueous solution HC supplied is calculated by the calculation unit 60b based on the concentration of chloride ions contained in the second aqueous solution L2. Specifically, the amount of high-concentration chloride aqueous solution HC supplied is calculated and determined by the calculation unit 60b based on the second voltage value acquired by the voltage acquisition unit 60a when the purification operation is stopped and the first threshold V1.

[0183] Immediately after the purification operation is stopped, the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 begins, and the concentration of chloride ions in the second aqueous solution L2 increases rapidly. When the second voltage value acquired by the voltage acquisition unit 60a reaches the first threshold V1 (when the supply of the amount of high-concentration chloride aqueous solution HC calculated by the calculation unit 60b is completed), the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 is stopped.

[0184] As a variation, if the concentration of chloride ions in the second aqueous solution L2 is higher than the concentration of chloride ions in the first aqueous solution L1 (first state P1), the supply of the high-concentration chloride aqueous solution HC by the delivery unit 31 is not required. In other words, if the purification operation is stopped when the second voltage value is below the reference threshold V0 (first state P1), the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 by the delivery unit 31 may be maintained so that the concentration of chloride ions in the second aqueous solution L2 is higher than the concentration of chloride ions in the first aqueous solution L1 (first state P1).

[0185] As described above, in this embodiment, the purification operation is stopped when the chloride ion concentration of the second aqueous solution L2 is higher than the chloride ion concentration of the first aqueous solution L1 (first state P1). As a result, when the purification operation is stopped, water moves from the first aqueous solution L1 to the second aqueous solution L2. However, if the amount of water moved exceeds a predetermined range, the electrolytic cell anode 11 and the electrolytic cell cathode 12 may be exposed as the amount of water in the first aqueous solution L1 decreases.

[0186] Therefore, in this embodiment, the first threshold V1 is set so that the voltage difference between it and the reference threshold V0 falls within a predetermined range. More specifically, the first threshold V1 is set so that the voltage difference corresponds to a concentration difference of 1% to 5% based on the initial chloride ion concentration, which is within a predetermined range.

[0187] This method suppresses excessive water movement from the first aqueous solution L1 to the second aqueous solution L2. This prevents exposure of the electrolytic cell-side anode 11 and electrolytic cell-side cathode 12 as the first aqueous solution L1 decreases.

[0188] As described above, the following effects can be enjoyed with the space purification device 1 according to the embodiment.

[0189] The air 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 electrolyzing the first aqueous solution L1; a chloride ion 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 permeating an anion exchange membrane 41 through diaphragm electrolysis; and a high-concentration chloride aqueous solution supply tank 30 that stores a high-concentration chloride aqueous solution HC containing a higher concentration of chloride ions than the second aqueous solution L2 and supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2. Air introduced from the indoor space R flows through the electrolytic cell 10 and is released into the indoor space R together with hypochlorous acid in a purification operation. If the purification operation is stopped when the concentration of chloride ions in the second aqueous solution L2 stored in the chloride ion supply tank 20 is lower than the concentration of chloride ions in the first aqueous solution L1 stored in the electrolytic cell 10, the high-concentration chloride aqueous solution HC stored in the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 so that the concentration of chloride ions in the second aqueous solution L2 becomes higher than the concentration of chloride ions in the first aqueous solution L1.

[0190] In this way, while the purification operation is stopped, the concentration of chloride ions in the second aqueous solution L2 stored in the chloride ion supply tank 20 can be made higher than the concentration of chloride ions in the first aqueous solution L1 stored in the electrolytic cell 10 (first state P1). In other words, the movement of water caused by the difference in chloride ion concentration in each tank can be made to be a movement from the first aqueous solution L1 to the second aqueous solution L2. This suppresses an increase in the amount of water in the first aqueous solution L1 and prevents the chloride ion concentration of the first aqueous solution L1 from becoming lower. As a result, when the purification operation is restarted, the chloride ion concentration of the first aqueous solution L1 does not become lower than the predetermined concentration, and the desired amount of hypochlorous acid gas can be stably generated. Furthermore, even when the purification operation is stopped for an even longer period, the increase in the amount of water in the first aqueous solution L1 This prevents water from overflowing from the electrolytic cell 10. 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 without supplying an aqueous solution containing chloride ions from an external source.

[0191] The air purification device 1 according to this embodiment includes a voltage acquisition unit 60a that acquires the voltage value (second voltage value) applied during diaphragm electrolysis (first diaphragm electrolysis), and a discharge unit 31 that delivers a high-concentration chloride solution HC from a high-concentration chloride solution supply tank 30 to a chloride ion supply tank 20 to replenish the chloride ions contained in the second aqueous solution L2 that have been reduced by diaphragm electrolysis. If the voltage value acquired when the concentration of chloride ions contained in the second aqueous solution L2 is the same as the concentration of chloride ions contained in the first aqueous solution L1 is defined as a reference threshold V0, the discharge unit 31 will supply the high-concentration chloride solution HC to the second aqueous solution L2 so that the voltage value becomes less than the reference threshold V0 when the purification operation is stopped when the voltage value acquired by the voltage acquisition unit 60a exceeds the reference threshold V0.

[0192] In this way, when the purification operation is stopped while the voltage value acquired by the voltage acquisition unit 60a exceeds the reference threshold V0, the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 so that the voltage value becomes less than the reference threshold V0. In other words, when the purification operation is stopped when the concentration of chloride ions in the second aqueous solution L2 is in the second state P2, the high-concentration chloride aqueous solution HC stored in the high-concentration chloride aqueous solution supply tank 30 is supplied to the second aqueous solution L2 so that the concentration of chloride ions in the second aqueous solution L2 becomes the first state P1. Since the supply of the high-concentration chloride aqueous solution HC is based on the voltage value applied in diaphragm electrolysis, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 with higher precision. Therefore, while the purification operation is stopped, water moves from the first aqueous solution L1 to the second aqueous solution L2, and the problems caused by the increase in the amount of water in the first aqueous solution L1 as described above 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 without supplying an aqueous solution containing chloride ions from an external source.

[0193] In this embodiment, the amount of high-concentration chloride aqueous solution HC supplied to the second aqueous solution L2 of the air purification device 1 is determined based on the voltage value (second voltage value) acquired by the voltage acquisition unit 60a when the purification operation is stopped, and the first threshold value V1, which is a value smaller than the reference threshold value V0.

[0194] In this way, the amount of high-concentration chloride aqueous solution HC to be supplied is determined based on the second voltage value and the first threshold V1 obtained when the purification operation is stopped. Therefore, even when the first and second voltage values ​​cannot be obtained after the purification operation is stopped, i.e., after the non-diaphragm electrolysis and diaphragm electrolysis are stopped, an amount of high-concentration chloride aqueous solution HC based on the voltage value can be supplied to the second aqueous solution L2. This makes it possible to determine the amount of high-concentration chloride aqueous solution HC supplied to the second aqueous solution L2 with high accuracy. Consequently, while the purification operation is stopped, water moves from the first aqueous solution L1 to the second aqueous solution L2, suppressing the problems caused by the increase in the amount of water in the first aqueous solution L1 as described above. Thus, 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 without supplying an aqueous solution containing chloride ions from an external source.

[0195] In the space purification device 1 according to this embodiment, the discharge unit 31 stops supplying the high-concentration chloride aqueous solution HC to the second aqueous solution L2 when the voltage value (second voltage value) acquired by the voltage acquisition unit 60a falls below the first threshold V1, which is a value smaller than the reference threshold V0.

[0196] In this way, if the voltage value (second voltage value) acquired by the voltage acquisition unit 60a falls below the first threshold V1, which is a value smaller than the reference threshold V0, the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 is stopped. Voltage value applied in diaphragm electrolysis Because it is based on voltage values, the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 can be stopped with high precision. This suppresses excessive water movement from the first aqueous solution L1 to the second aqueous solution L2, and prevents exposure of the electrolytic cell anode 11 and electrolytic cell cathode 12 due to excessive decrease in the first aqueous solution L1. Therefore, it is possible to provide a space purification device 1 that can generate a desired amount of hypochlorous acid gas more stably over a long period of time without supplying an aqueous solution containing chloride ions from the outside.

[0197] In the air purification device 1 according to this embodiment, the first threshold V1 is set so that the voltage difference between it and the reference threshold V0 falls within a predetermined range.

[0198] In this way, when supplying a high-concentration chloride aqueous solution HC to the second aqueous solution L2, it is possible to suppress the chloride ion concentration in the second aqueous solution L2 from becoming too high. As a result, the purification operation can be stopped when the chloride ion concentration in the second aqueous solution L2 is slightly higher than the chloride ion concentration in the first aqueous solution L1. Therefore, while the purification operation is stopped, an appropriate amount of water moves from the first aqueous solution L1 to the second aqueous solution L2, thereby suppressing the problems caused by the increase and decrease in the amount of water in the first aqueous solution L1 as described above. Thus, it is possible to provide a space purification device 1 that can generate a desired amount of hypochlorous acid gas more stably over a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0199] In this embodiment, when the air purification device 1 stops the purification operation while the voltage value (second voltage value) acquired by the voltage acquisition unit 60a is below the reference threshold V0, the discharge unit 31 does not supply the high-concentration chloride aqueous solution HC to the second aqueous solution L2, and maintains a state in which the concentration of chloride ions in the second aqueous solution L2 is higher than the concentration of chloride ions in the first aqueous solution L1.

[0200] In this way, when the purification operation is stopped while the voltage value (second voltage value) acquired by the voltage acquisition unit 60a is below the reference threshold V0, the discharge unit 31 does not supply the high-concentration chloride aqueous solution HC to the second aqueous solution L2, and the concentration of chloride ions in the second aqueous solution L2 is maintained to be higher than the concentration of chloride ions in the first aqueous solution L1. As a result, the purification operation can be stopped while the concentration of chloride ions in the second aqueous solution L2 maintains the first state P1. Because this is based on the voltage value applied in diaphragm electrolysis, the above control can be performed with high precision. Therefore, while the purification operation is stopped, water moves from the first aqueous solution L1 to the second aqueous solution L2, and the problems caused by the increase in the amount of water in the first aqueous solution L1 as described above can be suppressed. Thus, it is possible to provide a space purification device 1 that can generate a desired amount of hypochlorous acid gas more stably over a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0201] In the space purification device 1 according to this embodiment, the discharge unit 31 supplies a high-concentration chloride aqueous solution HC to the second aqueous solution L2 so that when the purification operation is stopped while the voltage value (second voltage value) acquired by the voltage acquisition unit 60a is less than the reference threshold V0, the voltage value (second voltage value) acquired by the voltage acquisition unit 60a becomes less than or equal to the first threshold V1, which is a value smaller than the reference threshold V0.

[0202] In this way, when the purification operation is stopped while the voltage value (second voltage value) acquired by the voltage acquisition unit 60a is below the reference threshold V0, the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 so that the voltage value (second voltage value) acquired by the voltage acquisition unit 60a becomes less than or equal to the first threshold V1, which is a value smaller than the reference threshold V0. This allows the purification operation to be stopped when the concentration of chloride ions contained in the second aqueous solution L2 is at the predetermined concentration in the first state P1. Because this is based on the voltage value applied in diaphragm electrolysis, the above control can be performed with high precision. Therefore, while the purification operation is stopped, water moves from the first aqueous solution L1 to the second aqueous solution L2, and as described above, the amount of water in the first aqueous solution L1 increases. This can suppress the malfunctions that occur. Furthermore, since the concentration of chloride ions in the second aqueous solution L2 is at a predetermined concentration, the desired amount of hypochlorous acid gas can be generated even more stably, especially immediately after restarting the purification operation. Therefore, it is possible to provide a space purification device 1 that can generate the desired amount of hypochlorous acid gas even more stably over a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0203] In the air purification device 1 according to this embodiment, the discharge unit 31 supplies a high-concentration chloride aqueous solution HC to the second aqueous solution L2 when the voltage value (second voltage value) acquired by the voltage acquisition unit 60a during the purification operation becomes a second threshold value V2 which is greater than the reference threshold value V0. After supplying the high-concentration chloride aqueous solution HC, the discharge unit 31 stops supplying the high-concentration chloride aqueous solution HC to the second aqueous solution L2 when the voltage value (second voltage value) acquired by the voltage acquisition unit 60a becomes the reference threshold value V0.

[0204] In this way, during the purification operation, when the voltage value acquired by the voltage acquisition unit 60a becomes a second threshold V2, which is greater than the reference threshold V0, the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2. After the supply of the high-concentration chloride aqueous solution HC, when the voltage value acquired by the voltage acquisition unit 60a becomes the reference threshold V0, the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 is stopped. In other words, the purification operation can be performed in a second state P2 where the concentration of chloride ions in the second aqueous solution L2 is lower than the concentration of chloride ions in the first aqueous solution L1. Therefore, during the purification operation, water moves from the second aqueous solution L2 to the first aqueous solution L1. This makes it possible to replenish the water evaporated from the first aqueous solution L1 by bubbling. Therefore, it is possible to provide a space purification device that can generate a desired amount of hypochlorous acid gas more stably over a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0205] Although the present invention has been described above based on embodiments, it can be easily inferred that the present invention is not limited in any way to the above embodiments, and that various improvements and modifications are possible without departing from the spirit of the present invention.

[0206] As mentioned above, in order for the chloride ion concentration of the second aqueous solution L2 to be at the predetermined concentration when the purification operation is restarted, an appropriate amount of water must be transferred from the first aqueous solution L1 to the second aqueous solution L2. The amount of water transferred increases as the concentration difference between the chloride ion concentration of the first aqueous solution L1 and the chloride ion concentration of the second aqueous solution L2 increases, and also increases as the duration of the concentration difference increases.

[0207] In the space purification device 1 according to Embodiment 1, when supplying a high-concentration chloride aqueous solution HC, the high-concentration chloride aqueous solution HC is supplied immediately after the purification operation is stopped so that the second voltage value becomes the first threshold V1. That is, the concentration difference between the chloride ion concentration of the first aqueous solution L1 and the chloride ion concentration of the second aqueous solution L2 is defined so that an appropriate amount of water moves from the first aqueous solution L1 to the second aqueous solution L2, but this is not limited to this.

[0208] For example, if the duration of the purification operation shutdown can be predicted, the high-concentration chloride aqueous solution HC may be supplied at a time tx after a certain period has elapsed since the shutdown of the purification operation. Specifically, after the purification operation shutdown, the second state P2 may be maintained, and water movement from the second aqueous solution L2 to the first aqueous solution L1 may occur for a certain period (time tx) before the high-concentration chloride aqueous solution HC is supplied. This makes it possible to offset and reduce the increase or decrease in water volume in each tank due to water movement that occurs while the purification operation is stopped. As a result, when the purification operation is restarted, the desired amount of hypochlorous acid gas can be generated stably. [Industrial applicability]

[0209] The air purification device according to this embodiment provides a desired amount of hypochlorous acid gas for a long period of time. Because it can generate the substance at regular intervals, it is useful as a device for purifying or disinfecting indoor spaces. [Explanation of symbols]

[0210] 1. Air purification device 10 Electrolytic cell 11 Electrolyzer side anode 12 Electrolytic cell side cathode 13 Air supply unit 14 Air duct 15 Internal space on electrolytic cell side 16 Water Recovery Section 17 Outlet 18 Water level detection unit 20 Chloride ion supply tank 21. Cathode on the side of the chloride ion supply tank 22. Internal space on the chloride ion supply tank side 23 1st outlet 30 High-concentration chloride solution supply tank 31 Dispatch unit 32 Suction tube 33 Dropping tube 41 Anion exchange membrane 42 Cation exchange membrane 50 Metal ion supply tank 51 Anode on the side of the metal ion supply tank 52 Internal space on the side of the metal ion supply tank 53 2nd outlet 60 Current control unit 60A Voltage Acquisition Unit 60b Calculation part 60c estimation part 60d storage section 61 Wiring 62 Wiring 63 Wiring 64 Wiring A air passage B bubbles C cabinet E1 1st diaphragm electrolytic section E2 Second diaphragm electrolytic section E3 Diaphragmless electrolytic section HC High-concentration chloride aqueous solution L1 1st aqueous solution L2 2nd aqueous solution L3 3rd aqueous solution M mixed air R Indoor space S1 liquid level S2 liquid level S3 liquid level P1 First state P2 Second State V0 threshold V1 First threshold V2 Second threshold

Claims

1. An electrolytic cell that stores a first aqueous solution containing chloride ions and generates hypochlorous acid by electrolyzing the first aqueous solution, A chloride ion supply tank stores a second aqueous solution containing chloride ions and supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by permeating an anion exchange membrane through diaphragm electrolysis, A high-concentration chloride aqueous solution supply tank that stores a high-concentration chloride aqueous solution containing chloride ions at a higher concentration than the second aqueous solution, and supplies the high-concentration chloride aqueous solution to the second aqueous solution, Equipped with, 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. When the purification operation is stopped while the concentration of chloride ions in the second aqueous solution stored in the chloride ion supply tank is lower than the concentration of chloride ions in the first aqueous solution stored in the electrolytic cell, the high-concentration chloride aqueous solution stored in the high-concentration chloride aqueous solution supply tank is supplied to the second aqueous solution so that the concentration of chloride ions in the second aqueous solution becomes higher than the concentration of chloride ions in the first aqueous solution. Air purification device.

2. A voltage acquisition unit that acquires the voltage value applied in the aforementioned diaphragm electrolysis, A dispensing unit that dispenses the high-concentration chloride aqueous solution from the high-concentration chloride aqueous solution supply tank to the chloride ion supply tank in order to replenish the chloride ions contained in the second aqueous solution that have been reduced by the diaphragm electrolysis, Equipped with, If the voltage value obtained when the concentration of chloride ions in the second aqueous solution is the same as the concentration of chloride ions in the first aqueous solution is used as the reference threshold, The aforementioned sending unit is, If the voltage value acquired by the voltage acquisition unit exceeds the reference threshold and the purification operation is stopped, the high-concentration chloride aqueous solution is supplied to the second aqueous solution so that the voltage value falls below the reference threshold. The air purification device according to claim 1.

3. The amount of the high-concentration chloride aqueous solution supplied to the second aqueous solution is determined based on the voltage value acquired by the voltage acquisition unit when the purification operation is stopped, and a first threshold value which is smaller than the reference threshold value. The air purification device according to claim 2.

4. The aforementioned sending unit is, When the voltage value acquired by the voltage acquisition unit falls below a first threshold value, which is smaller than the reference threshold value, the supply of the high-concentration chloride aqueous solution to the second aqueous solution is stopped. The air purification device according to claim 2.

5. The first threshold is set such that the voltage difference between it and the reference threshold is within a predetermined range. The air purification device according to claim 3.

6. The purification operation is performed when the voltage value acquired by the voltage acquisition unit is below the reference threshold value. When stopping, the discharge unit does not supply the high-concentration chloride aqueous solution to the second aqueous solution, and maintains a state in which the concentration of chloride ions in the second aqueous solution is higher than the concentration of chloride ions in the first aqueous solution. The air purification device according to claim 2.

7. The aforementioned sending unit is, If the purification operation is stopped when the voltage value acquired by the voltage acquisition unit is below the reference threshold, the high-concentration chloride aqueous solution is supplied to the second aqueous solution so that the voltage value acquired by the voltage acquisition unit becomes less than or equal to a first threshold value which is smaller than the reference threshold. The air purification device according to claim 2.

8. The aforementioned sending unit is, When the voltage value acquired by the voltage acquisition unit during the purification operation becomes a second threshold value which is greater than the reference threshold value, the high-concentration chloride aqueous solution is supplied to the second aqueous solution. After supplying the high-concentration chloride aqueous solution, if the voltage value acquired by the voltage acquisition unit reaches the reference threshold, the supply of the high-concentration chloride aqueous solution to the second aqueous solution is stopped. The air purification device according to claim 2.

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