Air purification device

Abstract

This invention provides a technology to suppress the reduction of the aqueous solution in the electrolytic cell due to evaporation, even when electrolysis is repeatedly performed in a miniaturized air purification device. [Solution] The electrolytic cell 30 stores a first aqueous solution L1 and generates hypochlorous acid from the first aqueous solution L1. The metal ion supply tank 20 stores a second aqueous solution L2 and supplies chloride ions contained in the second aqueous solution to the first aqueous solution L1. The first air passage 60 connects the internal space 12 on the chloride ion supply tank side and the internal space 35 on the electrolytic cell side. The water recovery unit 36 ​​recovers moisture contained in the air flowing from the electrolytic cell 30 as liquid and returns it to the electrolytic cell 30. The space purification device 1 performs a purification operation in which air introduced from the external space R flows through the electrolytic cell 30 and is released into the external space R together with hypochlorous acid. During the purification operation, gas generated in the metal ion supply tank 20 flows through the first air passage 60 and the electrolytic cell 30 and is released into the external space R together with the air.

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 removes bacteria, fungi, viruses, odors, etc. contained in the air by using hypochlorous acid generated by electrolyzing an aqueous sodium chloride solution.

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 is also miniaturized. 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, the aqueous solution in the electrolytic cell is likely to decrease due to evaporation.

[0005] The present invention has been made in view of the above problems, and provides a technique for suppressing the decrease in the aqueous solution in the electrolytic cell due to evaporation even when electrolysis is repeatedly performed in a miniaturized space purification device.

Means for Solving the Problems

[0006] To solve the above problems, a space purification device according to one aspect of the present invention includes an electrolytic cell that stores a first aqueous solution containing chloride ions and generates hypochlorous acid by non-diaphragm electrolysis of the first aqueous solution; a chloride ion supply tank that stores a second aqueous solution containing a higher concentration of chloride ions than the first aqueous solution and supplies chloride ions contained in the second aqueous solution to the first aqueous solution by permeating an anion exchange membrane through diaphragm electrolysis; a first air passage connecting an upper space on the chloride ion supply tank side formed above the liquid surface of the second aqueous solution and an upper space on the electrolytic cell side formed above the liquid surface of the first aqueous solution; and a water recovery unit that recovers moisture contained in the air flowing from the electrolytic cell as liquid and returns it to the electrolytic cell. Air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with hypochlorous acid in a purification operation, and in the purification operation, gas generated in the chloride ion supply tank flows through the first air passage and the electrolytic cell and is released into the outside space together with the air.

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

[0008] The present invention makes it possible to suppress the reduction of the aqueous solution in the electrolytic cell due to evaporation, even when electrolysis is repeatedly performed in a miniaturized air purification device. [Brief explanation of the drawing]

[0009] [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 partial cross-sectional plan view along the line II-II in Figure 1, showing a first example of each electrolytic unit in the air purification device. [Figure 3] Figure 3 is a partial cross-sectional plan view along the line II-II in Figure 1, showing a second example of the electrolytic units included in the air purification device. [Figure 4]Figure 4 shows a list of chemical reactions occurring in the first aqueous solution stored in the chloride ion 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 chloride ion supply tank of the second diaphragm electrolytic unit and in the second aqueous solution stored in the metal ion supply tank. [Figure 6] Figure 6 shows a list of chemical reactions occurring in the second aqueous solution stored in the metal ion supply tank of the second diaphragm electrolytic unit and in the third aqueous solution stored in the electrolytic cell. [Figure 7] Figure 7 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 8] Figure 8 is a block diagram showing the current control unit according to the embodiment. [Figure 9] Figure 9 is a flowchart showing the switching procedure using the air purification device shown in Figure 1. [Modes for carrying out the invention]

[0010] The specific embodiments of this disclosure will be described in detail below 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 represents the vertically upward direction. Also, the xy-plane is the horizontal plane and is consistent across all drawings.

[0011] <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 30, which will be described later, to generate and volatilize hypochlorous acid. The air purification device 1 removes bacteria, fungi, viruses, or odors contained in the air in the space outside the air purification device 1 by releasing the volatilized hypochlorous acid into the space outside the housing C that constitutes the air purification device 1.

[0012] 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 an air conditioner, around a fan, around a circulator, around a ceiling fan, inside a humidifier, inside an air purifier, and on a desk.

[0013] As shown in Figure 1, the air purification device 1 comprises a housing C, a chloride ion supply tank 10, a metal ion supply tank 20, an electrolytic cell 30, an anion exchange membrane 41, a cation exchange membrane 42, and a current control unit 50.

[0014] The housing C houses the chloride ion supply tank 10, the metal ion supply tank 20, the electrolytic cell 30, the anion exchange membrane 41, the cation exchange membrane 42, and the current control unit 50. 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, a rectangular parallelepiped or a cylindrical shape. 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 a rectangular parallelepiped, it is, for example, about 10 cm × 7 cm × 4 cm.

[0015] When considering continuous use of the chloride ion supply tank 10, metal ion supply tank 20, and electrolytic cell 30 for 8 hours a day for one year, it is preferable that the volume of the chloride ion supply tank 10 be approximately 12 times or more the volume of the electrolytic cell 30. It is also preferable that the volume of the metal ion supply tank 20 be approximately 6 times or more the volume of the electrolytic cell 30. By having such volume ratios, the chloride ion supply tank 10 can store a second aqueous solution L2 containing a sufficient amount of chloride ions to supply the first aqueous solution L1 of the electrolytic cell 30. The metal ion supply tank 20 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) to supply the first aqueous solution L1 of the electrolytic cell 30. Therefore, chloride ions can be stably supplied from the second aqueous solution L2 stored in the chloride ion supply tank 10 to the first aqueous solution L1 stored in the electrolytic cell 30. Similarly, the required amount of metal ions can be stably supplied from the third aqueous solution L3 stored in the metal ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 30. The amount of the first aqueous solution L1 stored in the electrolytic cell 30 is, for example, about 2 mL to 10 mL.

[0016] The chloride ion supply tank 10, the metal ion supply tank 20, and the electrolytic cell 30 are arranged in the order of metal ion supply tank 20, electrolytic cell 30, and chloride ion supply tank 10, starting from the negative x-axis side in a front view. An anion exchange membrane 41 is placed between the chloride ion supply tank 10 and the electrolytic cell 30. A cation exchange membrane 42 is placed between the metal ion supply tank 20 and the electrolytic cell 30. For example, if the surfaces of the chloride ion supply tank 10 and the electrolytic cell 30 facing each other are formed by a frame-shaped member, the anion exchange membrane 41 may be fitted into the frame-shaped member. Similarly, if the surfaces of the metal ion supply tank 20 and the electrolytic cell 30 facing each other are formed by a frame-shaped member, the cation exchange membrane 42 may be fitted into the frame-shaped member. The current control unit 50 is placed at any position within the housing C.

[0017] The chloride ion supply tank 10 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 10.

[0018] As the solute for the second aqueous solution L2, it is preferable to use a substance whose GHS (Globally Harmonized System of Classification and Labelling of Chemicals) classification is as safe as that of sodium chloride, in order to ensure safety in the event of leakage. Specifically, the second aqueous solution L2 is an aqueous metal chloride solution containing metal ions and chloride ions. By performing the first diaphragm electrolysis described later, the metal ions contained in the second aqueous solution L2 react with the hydroxide ions produced by the first diaphragm electrolysis to form a precipitate of metal hydroxide. Preferably, the second aqueous solution L2 is a high-concentration aqueous magnesium chloride solution or a saturated aqueous magnesium chloride solution.

[0019] When a magnesium chloride aqueous solution is used as the second aqueous solution L2, the mass percentage concentration of the magnesium chloride aqueous solution is, for example, 1% to 35%. As an example, when the second aqueous solution L2 is a magnesium chloride aqueous solution, 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.

[0020] The chloride ion supply tank 10 includes a chloride ion supply tank side cathode 11 and a chloride ion supply tank side internal space 12.

[0021] The chloride ion supply tank side cathode 11 is inserted into the chloride ion supply tank 10 from the outside toward the inside. The chloride ion supply tank side cathode 11 has a plate-like shape. The plate-like shape includes rectangular and rectangular shapes. The chloride ion supply tank side cathode 11 is used in the first diaphragm electrolysis via the anion exchange membrane 41 as a pair with the electrolytic cell side anode 31, which will be described later. Details of the first diaphragm electrolysis will be described later with reference to Figure 2. 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 11 and the electrolytic cell side anode 31.

[0022] An insoluble electrode may be used as the cathode 11 on the chloride 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.

[0023] The chloride ion supply tank side internal space 12 is an 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 10. In other words, the second aqueous solution L2 is not stored up to the upper interior surface of the chloride ion supply tank 10 (the xy plane on the positive z-axis side), and the chloride ion supply tank 10 has the chloride ion supply tank side internal space 12.

[0024] The metal ion supply tank 20 is a tank for storing the third aqueous solution L3 containing metal ions and supplying the metal ions contained in the third aqueous solution L3 to 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 20.

[0025] 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.

[0026] 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 each aqueous solution are shown below. The amounts of solute dissolved in each aqueous solution 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 as the air purification device 1 is used.

[0027] 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, 1 to 8 g per 100 g of water.

[0028] When using an aqueous sodium bicarbonate solution as the third aqueous solution L3, the amount of sodium bicarbonate solution that dissolves is, for example, 1 to 10 g per 100 g of water.

[0029] When lithium carbonate aqueous solution is used as the third aqueous solution L3, the amount of lithium carbonate aqueous solution that dissolves is, for example, 1 to 2 g per 100 g of water.

[0030] When using a potassium carbonate solution as the third aqueous solution L3, the amount of potassium carbonate solution that dissolves per 100g of water is, for example, 1 to 112g.

[0031] When using a combination of two solutions selected from the group consisting of disodium hydrogen phosphate aqueous solution, sodium bicarbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution as the third aqueous solution L3, the amount of dissolved solution in the mixed solution is, for example, 1 to 122 g per 100 g of water.

[0032] When using a combination of three solutions selected from the group consisting of disodium hydrogen phosphate aqueous solution, sodium bicarbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution as the third aqueous solution L3, the amount of dissolved solution in the mixed solution is, for example, 1 to 130 g per 100 g of water.

[0033] When a mixed solution consisting of four types of aqueous solutions—disodium hydrogen phosphate aqueous solution, sodium bicarbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution—is used as the third aqueous solution L3, the amount of the mixed solution that dissolves per 100g of water is, for example, 1 to 132g.

[0034] The metal ion supply tank 20 includes a metal ion supply tank side anode 21 and a metal ion supply tank side internal space 22.

[0035] The metal ion supply tank-side anode 21 is inserted into the metal ion supply tank 20 from the outside toward the inside. The metal ion supply tank-side anode 21 has a plate-like shape. The plate-like shape includes rectangular and rectangular shapes. The metal ion supply tank-side anode 21 is used in conjunction with the electrolytic cell-side cathode 32, which will be described later, for the second diaphragm electrolysis via the cation exchange membrane 42. Details of the second diaphragm electrolysis will be described later with reference to Figure 2. 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 21 and electrolytic cell-side cathode 32.

[0036] An insoluble electrode may be used as the anode 21 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.

[0037] The internal space 22 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 20. In other words, the third aqueous solution L3 is not stored up to the upper interior surface of the metal ion supply tank 20 (the xy plane on the positive z-axis side), and the metal ion supply tank 20 has the internal space 22 on the metal ion supply tank side.

[0038] The electrolytic cell 30 is a tank for storing the first aqueous solution L1 containing chloride ions. The electrolytic cell 30 has a box-like shape, for example. Figure 1 shows the state in which the first aqueous solution L1 is stored in the electrolytic cell 30. The first aqueous solution L1 is, for example, an aqueous solution in which an electrically conductive electrolyte is dissolved, and specifically it is a dilute chloride aqueous solution having a predetermined chloride ion concentration. More specifically, the first aqueous solution L1 is, for example, an aqueous sodium chloride solution or a dilute potassium chloride solution.

[0039] 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 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.

[0040] The electrolytic cell 30 includes an electrolytic cell-side anode 31, an electrolytic cell-side cathode 32, an air supply unit 33, a blower pipe 34, an electrolytic cell-side internal space 35, a water recovery unit 36, and a discharge port 37. The electrolytic cell 30 may further include a water level detection unit 38.

[0041] The electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 are a pair of electrodes used for the electrolysis of the first aqueous solution L1. The electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 are each inserted into the electrolytic cell 30 from the outside toward the inside. The electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 each have a plate-like shape. The plate-like shape includes rectangular and rectangular shapes.

[0042] Insoluble electrodes may be used as the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32. More specifically, for example, platinum-iridium titanium electrodes, platinum electrodes, ruthenium titanium electrodes, or iridium titanium oxide electrodes may be used.

[0043] There is no diaphragm, such as an ion exchange membrane, between the electrolytic cell anode 31 and the electrolytic cell cathode 32. In other words, the electrolysis of the first aqueous solution L1 performed using the pair of electrolytic cell anodes 31 and the electrolytic cell cathode 32 is diaphragm-free electrolysis. Hypochlorous acid, which is used for purifying the external space R, is generated by the diaphragm-free electrolysis of the first aqueous solution L1 performed using the pair of electrolytic cell anodes 31 and the electrolytic cell cathode 32.

[0044] The yz plane on the negative x-axis side of the electrolytic cell anode 31 and the yz plane on the positive x-axis side of the electrolytic cell cathode 32 are positioned opposite each other. This arrangement allows for a uniform electric field to be generated between the electrolytic cell anode 31 and the electrolytic cell cathode 32. 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 uneven degradation of the catalyst layer on the surface of each electrode caused by an uneven electric field can be suppressed. Consequently, a decrease in electrolysis efficiency can be suppressed.

[0045] The chloride ion supply tank 10 and the electrolytic cell 30 are connected by a tubular first air passage 60. Specifically, the first air passage 60 connects the chloride ion supply tank side internal space 12, which is formed above the liquid surface S2 of the second aqueous solution L2, and the electrolytic cell side internal space 35, which is formed above the liquid surface S1 of the first aqueous solution L1. The first air passage 60 is an air passage for sending air containing hydrogen, which is produced by the first diaphragm electrolysis of the second aqueous solution L2, to the electrolytic cell side internal space 35. A first moisture-permeable waterproof membrane 64 is inserted inside the first air passage 60. In other words, the first moisture-permeable waterproof membrane 64 is arranged over the entire diameter of the first air passage 60. The first moisture-permeable waterproof membrane 64 is a membrane that allows gas and the moisture (water vapor) contained in the gas to pass through, but does not allow liquid to pass through. More specifically, the first moisture-permeable waterproof membrane 64 allows air containing hydrogen and water vapor to pass through, but does not allow the second aqueous solution L2 to pass through. The arrangement of the first moisture-permeable waterproof membrane 64 prevents the second aqueous solution L2 from passing through the first air passage 60 and flowing into the electrolytic cell 30, even when the housing C is tilted so that the chloride ion supply tank 10 is above the electrolytic cell 30. Also, when the housing C is tilted so that the electrolytic cell 30 is above the chloride ion supply tank 10, it prevents the first aqueous solution L1 from passing through the first air passage 60 and flowing into the chloride ion supply tank 10.

[0046] The metal ion supply tank 20 and the electrolytic cell 30 are connected by a tubular second air passage 62. More specifically, the second air passage 62 connects the internal space 22 on the metal ion supply tank side, which is formed above the liquid surface S3 of the third aqueous solution L3, and the internal space 35 on the electrolytic cell side, which is formed above the liquid surface S1 of the first aqueous solution L1. The second air passage 62 is an air passage for sending oxygen-containing air, generated by the second diaphragm electrolysis of the third aqueous solution L3, to the internal space 35 on the electrolytic cell side. A second moisture-permeable waterproof membrane 66 is inserted inside the second air passage 62. In other words, the second moisture-permeable waterproof membrane 66 is arranged over the entire diameter of the second air passage 62. The second moisture-permeable waterproof membrane 66 is a membrane that allows gas and the moisture (water vapor) contained in the gas to pass through, but does not allow liquid to pass through. More specifically, the second moisture-permeable waterproof membrane 66 allows air containing oxygen and water vapor to pass through, but does not allow the third aqueous solution L3 to pass through. The placement of the second moisture-permeable waterproof membrane 66 prevents the third aqueous solution L3 from passing through the second air passage 62 and flowing into the electrolytic cell 30, even when the housing C is tilted so that the metal ion supply tank 20 is above the electrolytic cell 30. Furthermore, when the housing C is tilted so that the electrolytic cell 30 is above the metal ion supply tank 20, it prevents the first aqueous solution L1 from passing through the second air passage 62 and flowing into the electrolytic cell 30.

[0047] The air supply unit 33 is a blower, such as a fan, that introduces air from the external space R into the electrolytic cell 30. The air supply pipe 34 is a tubular member that connects the air supply unit 33 and the electrolytic cell 30. One end of the air supply unit 33 is located on the external space R side, and the other end is connected to the air supply pipe 34 side. One end of the air supply pipe 34 is connected to the air supply unit 33 side, and the other end is connected to the electrolytic cell 30 side. The end of the air supply pipe 34 located on the electrolytic cell 30 side is connected to the electrolytic cell 30 such that it is located below (negative z-axis side) the liquid level S1 of the first aqueous solution L1 stored in the electrolytic cell 30.

[0048] The air supply unit 33 supplies air from the external space R to the first aqueous solution L1 stored in the electrolytic cell 30 via the blower pipe 34. The air introduced into the first aqueous solution L1 via the air supply unit 33 and the blower pipe 34 is released as bubbles B. A moisture-permeable waterproof membrane (not shown) may be placed over the entire diameter of the blower pipe 34. The moisture-permeable waterproof membrane is a membrane that allows air, which is a gas supplied from the external space R, and the moisture (water vapor) contained in that air to pass through, but does not allow the first aqueous solution L1, which is a liquid, to pass through. The placement of this moisture-permeable waterproof membrane prevents backflow of the first aqueous solution L1 from the electrolytic cell 30 to the blower pipe 34.

[0049] The electrolytic cell-side internal space 35 is an upper space (space on the positive z-axis side) formed above the liquid surface S1 of the first aqueous solution L1 when the first aqueous solution L1 is stored in the electrolytic cell 30. In other words, the first aqueous solution L1 is not stored up to the upper interior surface of the electrolytic cell 30 (the xy plane on the positive z-axis side), and the electrolytic cell 30 has the electrolytic cell-side internal space 35. Air containing hydrogen released from the second aqueous solution L2 stored in the chloride ion supply tank 10 via the first air passage 60, and air containing oxygen released from the third aqueous solution L3 stored in the metal ion supply tank 20 via the second air passage 62 flow into the electrolytic cell-side internal space 35.

[0050] The water recovery unit 36 ​​is a component that circulates inside the air purification device 1 and recovers moisture contained in the air released from the electrolytic cell 30 into the external space R as a liquid and returns it to the electrolytic cell 30. The air containing hypochlorous acid (mixed air M) released from the electrolytic cell 30 into the external space R also contains hydrogen-containing air released from the second aqueous solution L2 stored in the chloride ion supply tank 10 via the first air passage 60, and oxygen-containing air released from the third aqueous solution L3 stored in the metal ion supply tank 20 via the second air passage 62. Therefore, the water recovery unit 36 ​​also recovers moisture contained in the hydrogen-containing air released from the second aqueous solution L2 stored in the chloride ion supply tank 10, and moisture contained in the oxygen-containing air released from the third aqueous solution L3 stored in the metal ion supply tank 20, as a liquid and returns it to the electrolytic cell 30.

[0051] As mentioned above, miniaturizing the air purification device 1 also miniaturizes the electrolytic cell 30. Miniaturizing the electrolytic cell 30 reduces the amount of first aqueous solution L1 that can be stored compared to a conventional air purification device. Therefore, if electrolysis is repeatedly performed in the miniaturized air purification device 1, the amount of first aqueous solution L1 in the electrolytic cell 30 tends to decrease due to evaporation. In this embodiment, by providing a first air passage 60 and a second air passage 62, the moisture contained in the hydrogen-containing air released from the second aqueous solution L2 stored in the chloride ion supply tank 10 and the moisture contained in the oxygen-containing air released from the third aqueous solution L3 stored in the metal ion supply tank 20 are also recovered as liquid in the first aqueous solution L1 stored in the electrolytic cell 30 by the water recovery unit 36. As a result, the decrease in the first aqueous solution L1 stored in the electrolytic cell 30 is suppressed.

[0052] The water recovery unit 36 ​​is, for example, a Peltier element that can cool and condense moisture contained in the air into water droplets. When the water recovery unit 36 ​​is a Peltier element, the Peltier element has a heat dissipation surface and a heat absorption surface, and a cooling heat sink is provided on the heat absorption surface. The cooling heat sink can cool and condense moisture contained in the air passing through it into water droplets. The water recovery unit 36 ​​may be placed at the discharge port 37 through which the air passes when it is released to the external space R in order to recover moisture contained in the air circulating inside the space purification device 1. When the water recovery unit 36 ​​is placed at the discharge port 37, moisture contained in the air that has circulated inside the space purification device 1 can be recovered efficiently. The water recovery unit 36 ​​may be placed at any position in the internal space 35 on the electrolytic cell side.

[0053] The airflow detection unit 39 is located downstream of the water recovery unit 36 ​​and detects the airflow rate of the hypochlorous acid-containing air (mixed air M) released from the first aqueous solution L1 stored in the electrolytic cell 30. Known technology can be used for the airflow detection unit 39; for example, a magnet is built into the float and the airflow rate is detected by a magnetic sensor. The hypochlorous acid-containing air released from the first aqueous solution L1 stored in the electrolytic cell 30 includes hydrogen-containing air released from the second aqueous solution L2 stored in the chloride ion supply tank 10 via the first air passage 60, and oxygen-containing air released from the third aqueous solution L3 stored in the metal ion supply tank 20 via the second air passage 62. Therefore, the hypochlorous acid-containing air released from the first aqueous solution L1 stored in the electrolytic cell 30 also contains hydrogen and oxygen.

[0054] The outlet 37 is an opening for releasing mixed air M, which is a mixture of air flowing in from the air supply unit 33 and hypochlorous acid generated from the first aqueous solution L1 by membraneless electrolysis, into the external space R of the housing C. The outlet 37 is also an opening for releasing hydrogen-containing air released from the first aqueous solution stored in the chloride ion supply tank 10, through the first air passage 60 and the internal space 35 on the electrolytic cell side of the electrolytic cell 30, together with the mixed air M, into the external space R. Furthermore, the outlet 37 is an opening for releasing oxygen-containing air released from the third aqueous solution L3 stored in the metal ion supply tank 20, through the second air passage 62 and the internal space 35 on the electrolytic cell side of the electrolytic cell 30, together with the mixed air M, into the external space R. In Figure 1, as an example, the outlet 37 is provided on the upper surface of the electrolytic cell 30 (the xy plane on the positive z-axis side), but it is sufficient for it to be positioned above the liquid level S1 of the first aqueous solution L1. The shape of the discharge port 37 is cylindrical, including, for example, a cylindrical or rectangular tube shape. If the upper surface (the surface on the positive z-axis side) of the electrolytic cell 30 is close to the ceiling surface of the housing C, the discharge port 37 may be a hole-like opening provided in a part of the upper surface of the electrolytic cell 30. Alternatively, the discharge port 37 and the upper surface (the surface on the positive z-axis side) of the housing C may be formed as a single unit.

[0055] The discharge port 37 may be equipped with an openable / closable or removable cover (not shown). The cover may be kept closed when transporting, moving, or installing the air purification device 1, and may be opened or removed when using the air purification device 1.

[0056] In the air purification device 1 according to this embodiment, air introduced from the external space R flows through the electrolytic cell 30 and is released back into the external 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 to the air purification device 1 from the external space R flows through the electrolytic cell 30 and is released back into the external space R as mixed air M containing hypochlorous acid. In other words, the airflow path A shows the flow of air from the external space R, the air supply unit 33, the blower pipe 34, the first aqueous solution L1 stored in the electrolytic cell 30, the internal space on the electrolytic cell side 35, the water recovery unit 36, the discharge port 37, and back into the external space R.

[0057] More specifically, in the air channel A, as shown in Figure 1, bubbles B are released from the external space R through the air supply unit 33 and the air blower 34 into the first aqueous solution L1 stored in the electrolytic cell 30. In other words, bubbles B are generated by bubbling the first aqueous solution L1 with air introduced from the external space R. Bubbles B and hypochlorous acid generated by the membraneless electrolysis of the first aqueous solution L1 are mixed to form mixed air M.

[0058] Here, the hypochlorous acid produced by the non-diaphragm electrolysis of the first aqueous solution L1 includes both hypochlorous acid dissolved in the first aqueous solution L1 and hypochlorous acid gas that has volatilized and gasified into the internal space 35 on the electrolytic cell side. The hypochlorous acid dissolved in the first aqueous solution L1 is mixed with bubbles B and released as mixed air M from the outlet 37 through the water recovery unit 36 ​​to the external space R. The hypochlorous acid gas that has volatilized and gasified into the internal space 35 on the electrolytic cell side is mixed with bubbles B which are mixed with hypochlorous acid and released as mixed air M from the outlet 37 through the water recovery unit 36 ​​to the external space R.

[0059] By generating bubbles B in the first aqueous solution L1 through bubbling, the bubbles B float towards the liquid surface S1 due to buoyancy, and as they do so, hypochlorous acid and bubbles B come into gas-liquid contact, allowing the bubbles B to absorb hypochlorous acid. In other words, compared to gas-liquid contact between air and the liquid surface S1 of the first aqueous solution L1, the gas-liquid contact by generating bubbles B in the first aqueous solution L1 through bubbling allows bubbles B to absorb more hypochlorous acid and release it into the external space R as mixed air M. The mixed air M contains water evaporated from the first aqueous solution L1, but this water contained in the mixed air M is recovered by the water recovery unit 36 ​​and returned to the first aqueous solution L1 as water droplets.

[0060] The mixed air M containing hypochlorous acid, released from the discharge port 37 into the external space R of the air purification device 1, purifies the external space R. In other words, the mixed air M containing hypochlorous acid removes bacteria, fungi, viruses, or odors contained in the air of the external space R of the enclosure C.

[0061] During the purification operation, air containing hydrogen generated from the second aqueous solution L2 stored in the chloride ion supply tank 10 also flows through the first air passage 60 and the internal space 35 on the electrolytic cell side of the electrolytic cell 30 and is released into the external space R from the outlet 37 together with the mixed air M. Similarly, during the purification operation, air containing oxygen generated from the third aqueous solution L3 stored in the metal ion supply tank 20 also flows through the second air passage 62 and the internal space 35 on the electrolytic cell side of the electrolytic cell 30 and is released into the external space R from the outlet 37 together with the mixed air M. The air containing hydrogen generated from the second aqueous solution L2 stored in the chloride ion supply tank 10 contains water evaporated from the second aqueous solution L2. Likewise, the air containing oxygen generated from the third aqueous solution L3 stored in the metal ion supply tank 20 contains water evaporated from the third aqueous solution L3. The moisture contained in the hydrogen-containing air generated from the second aqueous solution L2 stored in the chloride ion supply tank 10, and the moisture contained in the oxygen-containing air generated from the third aqueous solution L3 stored in the metal ion supply tank 20, are also recovered by the water recovery unit 36, just like the moisture contained in the mixed air M, and returned to the first aqueous solution L1 as water droplets.

[0062] The electrolytic cell 30 may further include a water level detection unit 38. The water level detection unit 38 detects the position of the liquid surface S1 in the first aqueous solution L1. The water level detection unit 38 is, for example, a water level sensor. The water level detection unit 38 is positioned at least above (on the positive z-axis side of) the upper end (the portion on the positive z-axis side of) the electrolytic cell side anode 31 and the electrolytic cell side cathode 32.

[0063] If the air purification device 1 is equipped with a water level detection unit 38, the water recovery unit 36 ​​recovers moisture from the mixed air M based on the position of the liquid level S1 detected by the water level detection unit 38 and supplies water to the electrolytic cell 30. More specifically, the water recovery unit 36 ​​supplies water to the electrolytic cell 30 so as not to fall below the upper ends (the portion on the positive z-axis) of the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32. Furthermore, the water recovery unit 36 ​​supplies water to the electrolytic cell 30 so as not to fall below the upper end (the portion on the positive z-axis) of the air blower pipe 34 connected to the electrolytic cell 30.

[0064] If the air purification device 1 is equipped with a water recovery unit 36 ​​and a water level detection unit 38, the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 can remain immersed in the first aqueous solution L1. Therefore, exposure of the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 to 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 10 and the metal ion supply tank 20 may also be equipped with water recovery units and water level detection units similar to those of the electrolytic cell 30.

[0065] The anion exchange membrane 41 is a membrane-like member that connects the chloride ion supply tank 10 and the electrolytic cell 30 in a way that allows anions to pass through, based on the voltage applied between the chloride ion supply tank 10 and the electrolytic cell 30. More specifically, when a voltage is applied between the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31, a first diaphragm electrolysis is performed via the anion exchange membrane 41. Through the first diaphragm electrolysis using the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31, 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).

[0066] The anion exchange membrane 41 in this embodiment is not an anion exchange membrane of the type 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 through the first diaphragm electrolysis using the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31, 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.

[0067] The plane on the anion exchange membrane 41 side of the chloride ion supply tank side cathode 11 (yz plane on the negative x-axis) and the plane on the anion exchange membrane 41 side of the electrolytic cell side anode 31 (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 chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31. 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.

[0068] Furthermore, the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31 are positioned in close proximity to the anion exchange membrane 41. In this specification, "close proximity" includes both a state in which the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31 are close to the anion exchange membrane 41 while maintaining a predetermined distance from each other, and a state in which the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31 are in contact with the anion exchange membrane 41.

[0069] The cation exchange membrane 42 is a membrane-like member that connects the metal ion supply tank 20 and the electrolytic cell 30 in a way that allows cations to pass through, based on the voltage applied between the metal ion supply tank 20 and the electrolytic cell 30. More specifically, when a voltage is applied between the metal ion supply tank 20 and the electrolytic cell 30, a second diaphragm electrolysis is performed via the cation exchange membrane 42. Through the second diaphragm electrolysis using the anode 21 on the metal ion supply tank side and the cathode 32 on the electrolytic cell 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).

[0070] 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, hydroxide ions, which are anions, do not permeate the cation exchange membrane 42. More specifically, 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 metal ion supply tank anode 21 and the electrolytic cell cathode 32, hydroxide ions, which are anions, do not permeate the cation exchange membrane 42.

[0071] The plane on the cation exchange membrane 42 side of the metal ion supply tank anode 21 (yz plane on the positive x-axis) and the plane on the cation exchange membrane 42 side of the electrolytic cell cathode 32 (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 metal ion supply tank anode 21 and the electrolytic cell cathode 32. 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.

[0072] Furthermore, the anode 21 on the metal ion supply tank side and the cathode 32 on the electrolytic cell side are positioned in close proximity to the cation exchange membrane 42. In this specification, "close proximity" includes both a state in which the anode 21 on the metal ion supply tank side and the cathode 32 on the electrolytic cell side are close to the cation exchange membrane 42 while maintaining a predetermined distance from each other, and a state in which the anode 21 on the metal ion supply tank side and the cathode 32 on the electrolytic cell side are in contact with the cation exchange membrane 42.

[0073] The current control unit 50 controls the current used for diaphragm electrolysis (first diaphragm electrolysis and second diaphragm electrolysis) and non-diaphragm electrolysis. The current control unit 50 is equipped with wiring 51, 52, 53, and 54. Wiring 51, 52, 53, and 54 are lines through which current flows. The chloride ion supply tank side cathode 11 is electrically connected to the current control unit 50 via wiring 51, the metal ion supply tank side anode 21 via wiring 52, the electrolytic cell side anode 31 via wiring 53, and the electrolytic cell side cathode 32 via wiring 54. Parts of each electrode may protrude outside each tank and be connected to the respective wiring.

[0074] Next, referring to Figures 2 and 3, the first diaphragm electrolytic unit E1, the second diaphragm electrolytic unit E2 (E2a, E2b), and the non-diaphragm electrolytic unit E3 of the air purification device 1 according to this embodiment will be described. The second diaphragm electrolytic unit E2 includes two examples, the second diaphragm electrolytic unit E2a and the second diaphragm electrolytic unit E2b, so the first example will be described in Figure 2 and the second example in Figure 3.

[0075] <First example: first diaphragm electrolytic section E1, second diaphragm electrolytic section E2a, non-diaphragm electrolytic section E3> Figure 2 is a partial cross-sectional plan view along the line II-II in Figure 1, showing a first example of each electrolytic unit in the air purification device 1. In Figure 2, the first diaphragm electrolytic unit E1 is shown as the area enclosed by a dashed rectangle, the second diaphragm electrolytic unit E2a is shown as the area enclosed by a double-dash rectangle, and the non-diaphragm electrolytic unit E3 is shown as the area enclosed by a dashed rectangle.

[0076] The first diaphragm electrolytic unit E1 is provided across the chloride ion supply tank 10 and the electrolytic cell 30. The first diaphragm electrolytic unit E1 comprises a chloride ion supply tank side cathode 11, an electrolytic cell side anode 31, 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 chloride ion supply tank side cathodes 11 and electrolytic cell side anodes 31.

[0077] The second diaphragm electrolysis unit E2a is provided across the chloride ion supply tank 10 and the metal ion supply tank 20. The second diaphragm electrolysis unit E2a comprises a cathode 11 on the chloride ion supply tank side, an anode 21 on the metal ion supply tank side, an anion exchange membrane 41, and a cation exchange membrane 42. The second diaphragm electrolysis unit E2a 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 11 on the chloride ion supply tank side and anodes 21 on the metal ion supply tank side.

[0078] The diaphragm-free electrolysis unit E3 is provided in the electrolytic cell 30. The diaphragm-free electrolysis unit E3 comprises an electrolytic cell-side anode 31 and an electrolytic cell-side cathode 32. The diaphragm-free electrolysis unit E3 generates hypochlorous acid by performing diaphragm-free electrolysis on a third aqueous solution by passing a third current between the pair of electrolytic cell-side anodes 31 and electrolytic cell-side cathodes 32.

[0079] As explained above, in the first example, the chloride ion supply tank side cathode 11 is used for the first diaphragm electrolysis and the second diaphragm electrolysis, and the electrolytic cell side anode 31 is used for the first diaphragm electrolysis and non-diaphragm electrolysis.

[0080] <Second example: first diaphragm electrolytic section E1, second diaphragm electrolytic section E2b, non-diaphragm electrolytic section E3> Figure 3 is a partial cross-sectional plan view along the line II-II in Figure 1, showing a second example of each electrolytic unit in the air purification device 1. In Figure 3, the first diaphragm electrolytic unit E1 is shown enclosed by a dashed rectangle, the second diaphragm electrolytic unit E2b is shown enclosed by a double-dash rectangle, and the non-diaphragm electrolytic unit E3 is shown enclosed by a dashed rectangle. The device configuration of the air purification device 1 in the second example, the first diaphragm electrolytic unit E1, and the non-diaphragm electrolytic unit E3 are the same as in the first example, so their explanation is omitted in this example, and only the second diaphragm electrolytic unit E2b will be explained.

[0081] The second diaphragm electrolysis unit E2b is provided across the metal ion supply tank 20 and the electrolytic cell 30. The second diaphragm electrolysis unit E2b comprises a metal ion supply tank side anode 21, an electrolytic cell side cathode 32, and a cation exchange membrane 42. The second diaphragm electrolysis unit E2b performs second diaphragm electrolysis via the cation exchange membrane 42 by passing a second current between the pair of metal ion supply tank side anodes 21 and electrolytic cell side cathodes 32.

[0082] As explained above, in the second example, the electrolytic cell anode 31 is used for the first diaphragm electrolysis and non-diaphragm electrolysis, and the electrolytic cell cathode 32 is used for the second diaphragm electrolysis and non-diaphragm electrolysis.

[0083] The current control unit 50 (see Figure 1) 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 50 can control the chemical reactions occurring in the first diaphragm electrolysis unit E1, the second current flowing through the second diaphragm electrolysis unit E2 (E2a, E2b), 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 (E2a, E2b), and the third current flowing through the non-diaphragm electrolysis unit E3.

[0084] The following describes in detail the chemical reactions occurring in the first diaphragm electrolytic section E1, the second diaphragm electrolytic section E2, and the non-diaphragm electrolytic section E3, using Figures 4 to 6. Furthermore, the following description will focus on the case where the second aqueous solution L2 is a magnesium chloride aqueous solution, the third aqueous solution L3 is a disodium hydrogen phosphate aqueous solution, and the first aqueous solution L1 is a sodium chloride aqueous solution.

[0085] [First diaphragm electrolytic section E1] In the first diaphragm electrolytic unit E1, reactions occur at both the chloride ion supply tank side cathode 11 and the electrolytic cell side anode 31 via the anion exchange membrane 41. That is, in the first diaphragm electrolytic unit E1, reactions occur at both the second aqueous solution L2 stored in the chloride ion supply tank 10 and the first aqueous solution L1 stored in the electrolytic cell 30.

[0086] Figure 4 shows a list of chemical reactions occurring in the second aqueous solution L2 stored in the chloride ion supply tank 10 of the first diaphragm electrolytic unit E1 and in the first aqueous solution L1 stored in the electrolytic cell 30.

[0087] 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 30, also occur in the non-diaphragm electrolytic unit E3 in the same manner as described below.

[0088] 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 30.

[0089] <Electrolytic cell 30 (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 31 and the chloride ion supply tank cathode 11, thereby transferring electrons (e) from the electrolytic cell anode 31 to the water (H2O) in the second aqueous solution L2 through the chloride ion supply tank cathode 11. -) moves. Also, chloride ions (Cl - ) contained in the second aqueous solution L2 stored in the chloride ion supply tank 10 permeate through the anion exchange membrane 41 and are supplied to the first aqueous solution L1 stored in the electrolytic cell 30. The chloride ions (Cl - ) supplied to the first aqueous solution L1 are used in the reaction formula (b) of FIG. 4 below. In other words, in the first aqueous solution L1, the electrons (e - ) before the first current flows (before the change) become chloride ions (Cl - ) after the first current flows (after the change).

[0090] Subsequently, as shown in the reaction formula (b) of FIG. 4 and the reaction formula (c) of FIG. 4, two types of reactions occur at the electrolytic cell side anode 31: chlorine (liquid) and oxygen (gas). · Reaction formula (b) of FIG. 4: Electrolytic cell side anode 31 (chlorine generation reaction) Sodium chloride (NaCl) contained in the sodium chloride aqueous solution, which is the first aqueous solution L1, ionizes into sodium ions (Na + ) and chloride ions (Cl - ) in water. 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 31, 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.

[0091] · Reaction formula (c) of FIG. 4: Electrolytic cell side anode 31 (oxygen generation reaction) At the electrolytic cell side anode 31, electrons (e - ) are taken away from the water (H2O) of the second aqueous solution L2, and oxygen (O2) and hydrogen ions (H + ) are generated.

[0092] · Reaction formula (d) of FIG. 4: In the first aqueous solution L1 (hypochlorous acid generation reaction) In the first aqueous solution L1 stored in the electrolytic cell 30, the chlorine (Cl2) generated in reaction equation (b) of Figure 4 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, releasing hydrogen ions (H + ) and chloride ions (Cl - It exists as ).

[0093] • Reaction equation (e) in Figure 4: 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 30, 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.

[0094] • 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.

[0095] 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 10.

[0096] <Chloride ion supply tank 10 (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 10 are released. - Chloride ions (Cl) supplied to the first aqueous solution L1 are supplied through the anion exchange membrane 41 and into the first aqueous solution L1 stored in the electrolytic cell 30. -) is used in the reaction equation (b) of Figure 4 described above. Also, when the first current flows between the electrolytic cell anode 31 and the chloride ion supply tank cathode 11, 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.

[0097] • Reaction equation (h) in Figure 4: Cathode 11 on the chloride ion supply tank side (hydrogen evolution reaction) At the chloride ion supply tank side cathode 11, water (H2O) in the second aqueous solution L2 is ionized (e - ) receives hydrogen (H2) and hydroxide ions (OH - ) is generated. Hydrogen volatilizes as a gas, and hydroxide ions are used in reaction equation (i) in Figure 4 below.

[0098] • 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.

[0099] 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 10, hydroxide ions (OH) generated in (g) of Figure 4 are present.- ) 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.

[0100] 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 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 10 after electrolysis, thereby providing a more safe air purification device 1.

[0101] 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.

[0102] Next, with reference to Figures 5 and 6, the chemical reactions occurring in the second diaphragm electrolytic unit will be explained. The second diaphragm electrolytic unit will be explained using Figure 5, including both the first example, the second diaphragm electrolytic unit E2a (see Figure 2 for its configuration), and the second example, the second diaphragm electrolytic unit E2b (see Figure 3 for its configuration). First, the first example, the second diaphragm electrolytic unit E2a, will be explained.

[0103] [Second diaphragm electrolytic section E2a] In the second diaphragm electrolytic unit E2a, reactions occur at both the chloride ion supply tank side cathode 11 and the metal ion supply tank side anode 21 via the anion exchange membrane 41 and the cation exchange membrane 42. That is, in the second diaphragm electrolytic unit E2a, reactions occur at both the second aqueous solution L2 stored in the chloride ion supply tank 10 and the third aqueous solution L3 stored in the metal ion supply tank 20. The reaction in the second diaphragm electrolytic unit E2a supplies chloride ions from the second aqueous solution L2 to the first aqueous solution L1 stored in the electrolytic cell 30, and supplies metal ions from the third aqueous solution L3 to the first aqueous solution L1 stored in the electrolytic cell 30. 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.

[0104] The reaction in the second diaphragm electrolytic unit E2a supplies chloride ions from the second aqueous solution L2 to the first aqueous solution L1 stored in the electrolytic cell 30, causing a hypochlorous acid generation reaction in the first aqueous solution L1, as explained using reaction equation (d) in Figure 4. In other words, when the second diaphragm electrolytic unit E2a is used, chloride ions are supplied from the second aqueous solution L2 stored in the chloride ion supply tank 10 to the first aqueous solution L1 stored in the electrolytic cell 30 by both the first diaphragm electrolytic unit E1 and the second diaphragm electrolytic unit E2a. In the second diaphragm electrolytic unit E2b, which will be described later, chloride ions are not supplied from the second aqueous solution L2 to the first aqueous solution L1. Therefore, for example, when the current amount of the first current is a predetermined value, using the second diaphragm electrolytic unit E2a allows more chloride ions to be supplied to the electrolytic cell 30 compared to using the second diaphragm electrolytic unit E2b.

[0105] Figure 5 shows a list of chemical reactions occurring in the second aqueous solution L2 stored in the chloride ion supply tank 10 of the second diaphragm electrolytic unit E2a, and in the third aqueous solution L3 stored in the metal ion supply tank 20.

[0106] When a predetermined voltage is applied to the second diaphragm electrolytic unit E2a, 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 occurring in the second aqueous solution L2 stored in the chloride ion supply tank 10 will be explained. Note that the chemical reaction occurring in the second aqueous solution L2 stored in the chloride ion supply tank 10 as shown in Figures 5(a) to (c) is substantially the same as the chemical reaction explained using Figures 4(g) to (i).

[0107] <Chloride ion supply tank 10 (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 10 are released. - Chloride ions (Cl) supplied to the first aqueous solution L1 are supplied through the anion exchange membrane 41 and into the first aqueous solution L1 stored in the electrolytic cell 30. - ) is used in the reaction equation (b) of Figure 4 described above. Also, when a second current flows between the chloride ion supply tank side cathode 11 and the metal ion supply tank side anode 21, water (H2O) of the second aqueous solution L2 is released from the metal ion supply tank side anode 21 through the chloride ion supply tank side cathode 11 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.

[0108] • Reaction equation (b) in Figure 5: Cathode 11 on the chloride ion supply tank side (hydrogen evolution reaction) At the chloride ion supply tank side cathode 11, water (H2O) in the second aqueous solution L2 is ionized (e - ) receives hydrogen (H2) and hydroxide ions (OH - ) is generated. Hydrogen volatilizes as a gas, and hydroxide ions are used in reaction equation (c) in Figure 5 below.

[0109] • 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 5. - ) reacts with the other to form a precipitate of magnesium hydroxide (Mg(OH)2), which is a metal hydroxide precipitate.

[0110] 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 20.

[0111] <Metal ion supply tank 20 (third aqueous solution L3)> • Reaction equation (d) in Figure 5: Anode 21 on the metal ion supply tank side (oxygen evolution reaction) At the metal ion supply tank anode 21, 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.

[0112] • Figure 5(e) Cation exchange membrane 42 When a voltage is applied to the second diaphragm electrolytic unit E2a 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 20 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 11 and the metal ion supply tank side anode 21, causing the electrons (e) generated in reaction equation (d) in Figure 5 to be supplied. - ) move from the anode 21 on the metal ion supply tank side to the cathode 11 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.

[0113] [Second diaphragm electrolytic section E2b] Next, with reference to Figure 6, we will describe the second example, the second diaphragm electrolytic unit E2b. Figure 6 is a list of chemical reactions that occur in the third aqueous solution L3 stored in the metal ion supply tank 20 of the second diaphragm electrolytic unit E2b and in the first aqueous solution L1 stored in the electrolytic cell 30.

[0114] In the second diaphragm electrolytic unit E2b, reactions occur at both the metal ion supply tank side anode 21 and the electrolytic cell side cathode 32 via the cation exchange membrane 42. That is, in the second diaphragm electrolytic unit E2b, reactions occur in both the third aqueous solution L3 stored in the metal ion supply tank 20 and the first aqueous solution L1 stored in the electrolytic cell 30. First, referring to Figures 6(a) to (b), the reaction occurring in the third aqueous solution L3 stored in the metal ion supply tank 20 will be explained. Note that the reaction occurring in the third aqueous solution L3 shown in Figures 6(a) to (b) is substantially the same as the chemical reaction explained using Figures 5(d) to (e).

[0115] <Metal ion supply tank 20 (third aqueous solution L3)> • Reaction equation (a) in Figure 6: Anode 21 on the metal ion supply tank side (oxygen evolution reaction) At the metal ion supply tank anode 21, electrons (e) are released from water (H2O) in the third aqueous solution L3. - ) is removed, and oxygen (O2) and hydrogen ions (H + Oxygen is generated. The generated oxygen volatilizes as a gas.

[0116] • Figure 6(b): Cation exchange membrane 42 When a voltage is applied to the second diaphragm electrolytic unit E2b 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 20 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 metal ion supply tank anode 21 and the electrolytic cell cathode 32, causing the electrons (e) generated in the reaction equation (a) of Figure 6 to be supplied. - ) moves from the metal ion supply tank anode 21 to the electrolytic cell cathode 32 to the first aqueous solution L1. 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 when ) is received is explained below using reaction equation (d) in Figure 6.

[0117] Next, referring to Figures 6(c) to 6(d), we will explain the reactions that occur in the first aqueous solution L1 stored in the electrolytic cell 30.

[0118] <Electrolytic cell 30 (first aqueous solution L1)> • Figure 6(c) Cation exchange membrane 42 As described above in Figure 6(b), when a voltage is applied to the second diaphragm electrolytic unit E2b 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.

[0119] • Reaction equation (d) in Figure 6: Electrolytic cell side cathode 32 (hydrogen evolution reaction) At the electrolytic cell cathode 32, water (H2O) in the first aqueous solution L1 is converted into electrons (e - ) receives hydrogen (H2) and hydroxide ions (OH - ) occurs.

[0120] Next, referring to Figure 7, 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 30 at both the electrolytic cell-side anode 31 and the electrolytic cell-side cathode 32 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 30.

[0121] [Diaphragmless electrolysis section E3 (electrolytic cell 30)] Figure 7 shows a list of reaction equations that occur in the first aqueous solution L1 stored in the electrolytic cell 30 of the diaphragm-free electrolytic unit E3. When a predetermined voltage is applied to the diaphragm-free electrolytic unit E3, a third current flows, electrons move, and the chemical reactions shown in Figure 7(a) to (h) occur.

[0122] 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 30.

[0123] Figure 7(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 E2a, and the first current and the second current flow, the first aqueous solution L1 stored in the electrolytic cell 30 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 10 through the anion exchange membrane 41 to the first aqueous solution L1 stored in the electrolytic cell 30. 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.

[0124] Next, as shown in reaction equation (b) in Figure 7 and reaction equation (c) in Figure 4, two types of reactions occur at the electrolytic cell anode 31: chlorine (liquid) and oxygen (gas).

[0125] • Reaction equation (b) in Figure 7: Anode 31 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 7(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 31, 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.)).

[0126] • Reaction equation (c) in Figure 7: Anode 31 on the electrolytic cell side (oxygen evolution reaction) At the electrolytic cell anode 31, electrons (e) are released from water (H2O) in the first aqueous solution L1. - ) is removed, and oxygen (O2) and hydrogen ions (H + ) occurs.

[0127] • Figure 7(d) Cation exchange membrane 42 When a voltage is applied to the second diaphragm electrolytic unit E2a or the second diaphragm electrolytic unit E2b 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.

[0128] • Reaction equation (e) in Figure 7: Electrolytic cell side cathode 32 (hydrogen evolution reaction) At the electrolytic cell cathode 32, water (H2O) in the first aqueous solution L1 is converted into electrons (e -) receives hydrogen (H2) and hydroxide ions (OH - ) occurs.

[0129] • Reaction equation (f) in Figure 7: In the first aqueous solution L1 (hypochlorous acid generation reaction) In the first aqueous solution L1 stored in the electrolytic cell 30, the chlorine (Cl2) generated in reaction equation (b) of Figure 7 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, releasing hydrogen ions (H + ) and chloride ions (Cl - It exists as (H). In addition, hydrogen ions generated in reaction equation (c) of Figure 7 are present in the first aqueous solution L1. + ) is the hydroxide ion (OH) generated in reaction equation (e) of Figure 7. - ) reacts with water. In other words, the generation of hydrogen ions in the first aqueous solution 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 32 - The reaction between ) and can suppress the decrease in pH of the first aqueous solution L1 that occurs with an increase in hydrogen ions.

[0130] • Reaction equation (g) in Figure 7: 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 30, 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.

[0131] • Equation (h) in Figure 7: Equation for the change in chloride ions during electrolysis Equation (h) in Figure 7 represents the combined reaction equations (b) and (f) in Figure 7. The chlorine (Cl2) produced by reaction equation (b) in Figure 7 is converted into hydrochloric acid (HCl) and hypochlorous acid (HClO) according to reaction equation (f) in Figure 7.

[0132] The current control unit 50 controls the above chemical reaction. Here, during the purification operation of the air purification device 1, the bubbling of the first aqueous solution L1 causes 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 30 located in the internal space 35 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 30 crystallizes and turns white, which is known as salt splashing. Salt splashing also includes the splashing of the sodium chloride aqueous solution into the external space R as droplets along with the mixed air M released from the outlet 37. Therefore, in the electrolytic cell 30, (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 (Cl) due to salt splashing - A decrease may occur.

[0133] The following describes the current control performed in the first and second examples, which have different configurations for the second diaphragm electrolytic unit E2. <First example: First diaphragm electrolytic section E1, second diaphragm electrolytic section E2a, non-diaphragm electrolytic section E3> The current control unit 50 (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 50 (2) controls the second current of the second diaphragm electrolysis unit E2a 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 50 supplies the chloride 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 in the third aqueous solution L3 is maintained at a predetermined concentration.

[0135] <Second example: First diaphragm electrolytic part E1, second diaphragm electrolytic part E2b, non-diaphragm electrolytic part E3> The current control unit 50 (1) supplies chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by permeating the anion exchange membrane 41, by controlling the first current to compensate for 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 50 (2) supplies chloride ions contained in the second aqueous solution L2 and sodium ions contained in the third aqueous solution L3 to the first aqueous solution L1 by controlling the first current and the second current of the second diaphragm electrolysis unit E2b to compensate for the chloride ions and sodium ions contained in the first aqueous solution L1 that have been reduced by salt evaporation.

[0136] The current control unit 50 supplies the chloride 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 in the third aqueous solution L3 is maintained at a predetermined concentration.

[0137] Here, the configuration of the current control unit 50 will be explained using Figure 8. Figure 8 is a block diagram of the current control unit 50 according to an embodiment. As shown in Figure 8, the current control unit 50 includes a voltage acquisition unit 50a, a calculation unit 50b, an estimation unit 50c, and a switching unit 50d. The current control unit 50 may further include a notification unit 50e.

[0138] The voltage acquisition unit 50a acquires the voltage between the electrolytic cell anode 31 and the electrolytic cell cathode 32. The voltage acquisition unit 50a is, for example, a voltmeter. The calculation unit 50b calculates the conductivity of the first aqueous solution L1 based on the voltage acquired by the voltage acquisition unit 50a. The estimation unit 50c 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 50b. Below, three types of control examples of current control by the current control unit 50 will be described. Similar control is performed in both the first and second examples, which have different configurations for the second diaphragm electrolysis. In both the first and second examples, which have different configurations for the second diaphragm electrolysis, before the current control unit 50 changes the current ratios of the first current (first diaphragm electrolysis), the second current (second diaphragm electrolysis), and the third current (non-diaphragm electrolysis), the third current has the largest current ratio, followed by the first current, and then the second current has the smallest current ratio. Details of the switching unit 50d and the notification unit 50e will be described later.

[0139] <First example: First diaphragm electrolytic section E1, second diaphragm electrolytic section E2a, non-diaphragm electrolytic section E3> [1. When the first current, second current, and third current are flowing simultaneously] When the current control unit 50 simultaneously supplies the first current, the second current, and the third current, it performs control to change or not change the current ratios of (1) to (3) below. (1) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is lower than a predetermined concentration: The current ratios of the first current, second current, and third current are changed so that the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41 increases. More specifically, the current ratio of the first current is not increased or changed, the current ratio of the second current is increased, and the current ratio of the third current is not increased or changed. In the first example, by flowing the first current, chloride ions are supplied from the second aqueous solution L2 stored in the chloride ion supply tank 10 to the first aqueous solution L1 stored in the electrolytic cell 30. Furthermore, by flowing the second current, chloride ions are also supplied from the second aqueous solution L2 stored in the chloride ion supply tank 10 to the first aqueous solution L1 stored in the electrolytic cell 30. On the other hand, in the second example described later, the second current flowing through the second diaphragm electrolytic unit E2b does not supply chloride ions from the second aqueous solution L2 to the first aqueous solution L1. Therefore, when the second diaphragm electrolytic unit E2a is used, more chloride ions can be supplied to the electrolytic cell 30 compared to when the second diaphragm electrolytic unit E2b is used.

[0140] Furthermore, if it is desired to supply chloride ions from the third aqueous solution L3 to the first aqueous solution L1 in order to increase the supply amount of chloride ions by a predetermined amount, when using the second diaphragm electrolytic unit E2a, the predetermined amount of chloride ions can be supplied from the third aqueous solution L3 to the first aqueous solution L1 by increasing only the second current, or by increasing both the first and second currents.

[0141] On the other hand, when using the second diaphragm electrolytic unit E2b in the second example described later, if it is desired to supply a predetermined amount of chloride ions from the third aqueous solution L3 to the first aqueous solution L1 in order to increase the supply amount of chloride ions, it is necessary to supply a predetermined amount of chloride ions from the third aqueous solution L3 to the first aqueous solution L1 by increasing the first current amount of the first diaphragm electrolysis.

[0142] Here, if the first current of the first diaphragm electrolysis and the second current of the second diaphragm electrolysis are increased so that the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41 increases, the amount of hydrogen ions in the first aqueous solution L1 increases due to the oxygen evolution reaction at the electrolytic cell anode 31 (see reaction equation (c) in Figure 7). When hydrogen ions increase, the pH of the first aqueous solution L1 decreases, which may suppress the generation of hypochlorous acid. Therefore, in the first example, by increasing both the first and second currents, a predetermined amount of chloride ions can be supplied from the first aqueous solution L1 to the third aqueous solution L3. Compared to the case where the second diaphragm electrolysis unit E2b is used in the second example, the increase in hydrogen ions in the first aqueous solution L1 associated with the increase in the current ratio of the first current (increase in current amount) can be suppressed, and the decrease in pH of the first aqueous solution L1 can be suppressed. In addition, the second diaphragm electrolysis unit E2b performs separate control to suppress the decrease in pH of the first aqueous solution L1. This control will be described later.

[0143] (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is higher than a predetermined concentration: The first current, second current, and third current are changed so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 decreases. More specifically, the current ratio of the first current is reduced or not changed, the current ratio of the second current is reduced, and the current ratio of the third current is increased or not changed.

[0144] (3) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is a predetermined concentration: the current ratios of the first current, second current and third current are not changed.

[0145] [2. When the third current flows at a predetermined value while simultaneously controlling the first and second currents] When the current control unit 50 controls the first and second currents at the same time as flowing the third current at a predetermined value, it performs the following controls (1) to (3). (1) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is lower than a predetermined concentration: The first and second currents are flowed so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 increases. For example, the first and third currents are flowed at predetermined values, and the second current is increased so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 increases. The second current may also be stopped if the chloride ion concentration of the first aqueous solution L1 is above a predetermined concentration. If the second current has been stopped, the stop of the second current is released and the second current is flowed so that the amount of chloride ions supplied to the first aqueous solution L1 increases. (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is higher than a predetermined concentration: The first and second currents are stopped so that the supply of chloride ions from the third aqueous solution L3 to the first aqueous solution L1 is stopped. (3) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is a predetermined concentration: the current ratios of the first current, second current and third current are not changed.

[0146] [3. When applying the first and second currents, or the third current] When the current control unit 50 supplies the first current and the second current, or the third current, it performs the following controls (1) to (3). (1) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is lower than a predetermined concentration: The third current is stopped and the first and second currents are turned on at the same time so that the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41 increases. (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is higher than a predetermined concentration: The first and second currents are stopped and the third current is simultaneously introduced so that the supply of chloride ions from the second aqueous solution L2 to the first aqueous solution L1 is stopped. (3) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is a predetermined concentration: the current ratios of the first current, second current and third current are not changed.

[0147] As described above, the current control unit 50 controls the first current, the second current, and the third current, thereby supplying the necessary amount of chloride ions to the first aqueous solution L1 stored in the electrolytic cell 30 and maintaining the hypochlorous acid concentration of the first aqueous solution L1 at a predetermined concentration.

[0148] <Second example: First diaphragm electrolytic part E1, second diaphragm electrolytic part E2b, non-diaphragm electrolytic part E3> [1. When the first current, second current, and third current are flowing simultaneously] When the current control unit 50 simultaneously supplies the first current, the second current, and the third current, it performs control to change or not change the current ratios of (1) to (3) below. (1) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is lower than a predetermined concentration: The current ratios of the first current, second current, and third current are changed so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 increases. More specifically, the current ratio of the first current is increased, the current ratio of the second current is increased in proportion to the increase in the current ratio of the first current, and the current ratio of the third current is not increased or changed.

[0149] Here, if the amount of the first current in the first diaphragm electrolysis is increased so that the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41 increases, the amount of hydrogen ions in the first aqueous solution L1 increases due to the oxygen evolution reaction at the electrolytic cell anode 31 (see reaction equation (c) in Figure 7). When hydrogen ions increase, the pH of the first aqueous solution L1 decreases, and the generation of hypochlorous acid may be suppressed. Therefore, in the second example, by increasing the current ratio of the second current in accordance with the increase in the current ratio of the first current, the amount of current flowing to the electrolytic cell cathode 32 also increases, and hydroxide ions (OH) are generated. - The formation of ) is promoted (see reaction equation (e) in Figure 7).

[0150] Therefore, the hydrogen ions that increase by increasing the current ratio of the first current react with hydroxide ions generated by increasing the current ratio of the second current to form water. Thus, by increasing the current ratio of the second current in a manner corresponding to the increase in the current ratio of the first current, the decrease in pH of the first aqueous solution L1 due to the increase in hydrogen ions can be suppressed.

[0151] (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is higher than a predetermined concentration: The first current, second current, and third current are changed so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 decreases. More specifically, the current ratio of the first current is decreased, the current ratio of the second current is decreased, and the current ratio of the third current is increased or not changed.

[0152] (3) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is a predetermined concentration: the current ratios of the first current, second current and third current are not changed.

[0153] [2. When the third current flows at a predetermined value while simultaneously controlling the first and second currents] When the current control unit 50 controls the first and second currents at the same time as flowing the third current at a predetermined value, it performs the following controls (1) to (3). (1) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is lower than a predetermined concentration: The first and second currents are flowed so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 increases. For example, the first and third currents are flowed at predetermined values, and the second current is increased so that the amount of chloride ions supplied from the second aqueous solution L2 through the anion exchange membrane 41 to the first aqueous solution L1 increases. The second current may also be stopped if the chloride ion concentration of the first aqueous solution L1 is above a predetermined concentration. If the second current has been stopped, the stop of the second current is released and the second current is flowed so that the amount of chloride ions supplied to the first aqueous solution L1 increases. (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is higher than a predetermined concentration: The first and second currents are stopped so that the supply of chloride ions from the third aqueous solution L3 to the first aqueous solution L1 is stopped. (3) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is a predetermined concentration: the current ratios of the first current, second current and third current are not changed.

[0154] [3. When applying the first and second currents, or the third current] When the current control unit 50 supplies the first current and the second current, or the third current, it performs the following controls (1) to (3). (1) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is lower than a predetermined concentration: The third current is stopped and the first and second currents are turned on at the same time so that the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41 increases. (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is higher than a predetermined concentration: The first and second currents are stopped and the third current is simultaneously introduced so that the supply of chloride ions from the second aqueous solution L2 to the first aqueous solution L1 is stopped. (3) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 50c is a predetermined concentration: the current ratios of the first current, second current and third current are not changed.

[0155] As described above, the current control unit 50 controls the first current, the second current, and the third current, thereby supplying the necessary amount of chloride ions to the first aqueous solution L1 stored in the electrolytic cell 30 and maintaining the hypochlorous acid concentration of the first aqueous solution L1 at a predetermined concentration.

[0156] In the case described above, "1. When the first, second, and third currents are applied simultaneously," the ratio of the first, second, and third currents is changed when there is an increase or decrease in the chloride ion concentration of the first aqueous solution L1. Because the first, second, and third currents are applied simultaneously, the increase or decrease in the chloride ion concentration of the first aqueous solution L1 can be minimized, and it can be maintained at the optimal predetermined concentration.

[0157] In the case described in "2. When the third current is flowing at a predetermined value and the first and second currents are controlled simultaneously," the first and second currents are mainly flowed or stopped when there is an increase or decrease in the chloride ion concentration of the first aqueous solution L1. In the case described in "3. When the first and second currents, or the third current, are flowing," when there is an increase or decrease in the chloride ion concentration of the first aqueous solution L1, either the first and second currents, or the third current, is flowed, and the other is stopped. Therefore, the chloride ion concentration of the first aqueous solution L1 can be maintained at a predetermined concentration. In cases 2 and 3 above, it is only necessary to control either the first and second currents, or the third current, making current control easy.

[0158] As described above, since chloride ions consumed by the first aqueous solution L1 can be appropriately supplied from the second aqueous solution L2, a space purification device 1 capable of stably generating a desired amount of hypochlorous acid gas can be provided. 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.

[0159] Alternatively, multiple current control units 50 may be provided to control the first current, second current, and third current separately.

[0160] Furthermore, if the current control unit 50 does not include an estimation unit 50c, a memory unit may be provided instead of the estimation unit 50c to store the correspondence between the decrease in chloride ions due to non-diaphragm electrolysis and the decrease in chloride ions due to salt evaporation, and a predetermined time. Based on the memory unit, the current control unit 50 may perform control to increase the current ratio of the first current and / or the second current in order to supply chloride ions from the second aqueous solution L2 to the first aqueous solution L1 when a predetermined time has elapsed.

[0161] 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.

[0162] As mentioned above, if electrolysis is continued when the airflow from the air purification device decreases, the concentration of hypochlorous acid in the first aqueous solution L1 in the electrolytic cell 30 will become high, and when the airflow recovers to the expected amount (above the standard airflow), there is a risk that air containing a high concentration of hypochlorous acid gas will be released as mixed air M. Furthermore, if electrolysis is continued with a reduced airflow, heat may accumulate in the electrolytic cell 30, which may accelerate the corrosion and deterioration of the electrodes (electrolytic cell anode 31, electrolytic cell cathode 32). In addition, if electrolysis is continued with a reduced airflow, the concentration of hypochlorous acid in the electrolytic cell will become high, which may accelerate the corrosion and deterioration of the ion exchange membrane (anion exchange membrane 41, cation exchange membrane 42) and, if the water recovery section is a Peltier element, the cooling heat sink provided by the Peltier element. Furthermore, the release of air containing an excess amount of hypochlorous acid gas into the external space R may cause an excessive increase in the hypochlorous acid concentration in the air of the external space R, potentially causing discomfort to occupants. To solve at least one of these problems, the current control unit 50 according to this embodiment performs the following processing.

[0163] The switching unit 50d in the current control unit 50 receives the airflow rate of the air containing hypochlorous acid detected by the airflow rate detection unit 39 from the airflow rate detection unit 39. For example, the switching unit 50d periodically receives the airflow rate of the air containing hypochlorous acid. Here, the airflow rate of the air containing hypochlorous acid decreases if foreign matter such as dust clogs the air supply unit 33, the blower pipe 34, or the outlet 37. Also, the airflow rate of the air containing hypochlorous acid decreases if scale originating from components contained in the first aqueous solution L1 forms and clogs the connection between the blower pipe 34 and the electrolytic cell 30, or the outlet 37. The switching unit 50d stores a reference airflow rate to be compared with the airflow rate in advance. The reference airflow rate is a value at which the hypochlorous acid concentration in the electrolytic cell 30 is determined to be high, and is derived in advance by means of simulation, experiment, etc. More specifically, for example, if the normal airflow rate is "1", the reference airflow rate is "0.7".

[0164] The switching unit 50d decides to stop at least the first and second diaphragm electrolysis out of the non-diaphragm electrolysis, first diaphragm electrolysis, and second diaphragm electrolysis if the airflow volume of the air containing hypochlorous acid detected by the airflow volume detection unit 39 falls below the standard airflow volume. In other words, if the airflow volume of the air containing hypochlorous acid falls below the standard airflow volume during purification, the switching unit 50d stops at least the first and second currents. By stopping the first and second diaphragm electrolysis, the supply of chloride ions to the electrolytic cell via the anion exchange membrane 41 and the supply of metal ions to the electrolytic cell 30 via the cation exchange membrane 42 are stopped. By stopping the supply of chloride ions, which are the source of hypochlorous acid, to the electrolytic cell 30, an upper limit is set on the total amount of hypochlorous acid gas that can be generated in the electrolytic cell 30, thereby suppressing the increase in the concentration of hypochlorous acid in the first aqueous solution L1. By suppressing the increase in the concentration of hypochlorous acid in the first aqueous solution L1, the release of high-concentration hypochlorous acid gas when the airflow rate of the hypochlorous acid-containing air recovers to above the standard airflow rate is suppressed. Furthermore, by stopping the first and second diaphragm electrolysis, the airflow rate of the hypochlorous acid-containing air falls below the standard airflow rate, and chloride ions and metal ions continue to be supplied in a situation where hypochlorous acid gas is not released from the first aqueous solution L1. This prevents the first aqueous solution L1 from becoming a strong acid or strong alkali outside the pH range of 5 to 10, thus suppressing premature deterioration of the anion exchange membrane 41 and cation exchange membrane 42.

[0165] In addition, as another process, the switching unit 50d decides to stop the non-diaphragm electrolysis in addition to stopping the first diaphragm electrolysis and the second diaphragm electrolysis if the airflow volume of the air containing hypochlorous acid detected by the airflow volume detection unit 39 falls below the standard airflow volume during the purification operation. That is, if the airflow volume of the air containing hypochlorous acid detected by the airflow volume detection unit 39 falls below the standard airflow volume during the purification operation, the switching unit 50d stops the third current along with the first and second currents. By stopping the non-diaphragm electrolysis, the generation of hypochlorous acid from chloride ions remaining in the electrolytic cell 30 at the time the first and second diaphragm electrolysis are stopped is halted. By stopping the generation of hypochlorous acid, the concentration of hypochlorous acid in the electrolytic cell 30 can be suppressed. Therefore, the release of high-concentration hypochlorous acid gas when the airflow volume of the air containing hypochlorous acid recovers to above the standard airflow volume is suppressed.

[0166] Furthermore, during normal diaphragm-free electrolysis in purification operation, heat of approximately 1W-4W is generated. The switching unit 50d stops diaphragm-free electrolysis when the airflow of hypochlorous acid-containing air falls below the standard airflow, thereby suppressing heat buildup in the electrolytic cell 30 and preventing corrosion and deterioration of the electrodes. Additionally, the switching unit 50d stops diaphragm-free electrolysis during purification operation when the airflow of hypochlorous acid-containing air falls below the standard airflow, thereby suppressing the increase in hypochlorous acid concentration in the electrolytic cell 30 and preventing corrosion and deterioration of the cooling heat sinks of the ion exchange membrane and Peltier element.

[0167] Furthermore, the switching unit 50d stops diaphragm-free electrolysis when the airflow rate of the hypochlorous acid-containing air falls below the standard airflow rate during the purification operation, thereby suppressing the consumption of water contained in the first aqueous solution L1 stored in the electrolytic cell 30. By suppressing water consumption, it is possible to prevent the electrolytic cell-side anode 31 and electrolytic cell-side cathode 32 from being exposed above the liquid surface S1 of the first aqueous solution L1.

[0168] Furthermore, if the airflow of hypochlorous acid-containing air released from the electrolytic cell 30 falls below the standard airflow rate, non-diaphragm electrolysis is stopped. This suppresses the generation of hypochlorous acid from chloride ions remaining in the electrolytic cell 30 when the first and second diaphragm electrolysis are stopped, thereby preventing the first aqueous solution L1 from becoming strongly alkaline with a pH of 11 or higher. By suppressing the strong alkalinity of the first aqueous solution L1, the deterioration of the electrolytic cell 30 can be suppressed.

[0169] The switching unit 50d decides to restart the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis after a predetermined time has elapsed since stopping the diaphragm electrolysis (first diaphragm electrolysis and second diaphragm electrolysis) and the non-diaphragm electrolysis, if the airflow volume of the air containing hypochlorous acid detected by the airflow volume detection unit 39 recovers to the expected airflow volume (standard airflow volume or higher). In other words, after a predetermined time has elapsed since stopping the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis, if the airflow volume of the air containing hypochlorous acid detected by the airflow volume detection unit 39 recovers to the standard airflow volume or higher, the switching unit 50d restarts supplying the first current, the second current, and the third current. As described above, stopping the diaphragm electrolysis stops the supply of chloride ions, which are the source of hypochlorous acid, to the electrolytic cell 30. Therefore, an upper limit is set on the total amount of hypochlorous acid gas that can be generated in the electrolytic cell 30, thereby suppressing the increase in the concentration of hypochlorous acid in the first aqueous solution L1. By suppressing the increase in the concentration of hypochlorous acid in the first aqueous solution L1, the release of high-concentration hypochlorous acid gas is suppressed when the airflow rate of the hypochlorous acid-containing air recovers to the expected amount (above the standard airflow rate). Furthermore, by stopping the non-diaphragm electrolysis, the generation of hypochlorous acid is stopped, which suppresses the increase in the concentration of hypochlorous acid in the electrolytic cell 30. Therefore, the release of high-concentration hypochlorous acid gas is suppressed when the airflow rate of the hypochlorous acid-containing air recovers to the expected amount (above the standard airflow rate).

[0170] Furthermore, if the switching unit 50d decides to restart the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis, it decides to continue operating the water recovery unit 36. In that case, the switching unit 50d keeps the water recovery unit 36 ​​running. Furthermore, if the switching unit 50d decides to restart the non-diaphragm electrolysis, the first diaphragm electrolysis, and the second diaphragm electrolysis, it decides to continue operating the air supply unit 33. In that case, the switching unit 50d keeps the air supply unit 33 running.

[0171] On the other hand, the switching unit 50d decides to stop the water recovery unit 36 ​​if, after a predetermined time has elapsed since stopping the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis, the airflow detection unit 39 detects that the airflow of the hypochlorous acid-containing air is less than the standard airflow. In that case, the switching unit 50d stops the water recovery unit 36.

[0172] Here, if the air supply unit 33 is left running while foreign matter is clogging the air supply unit 33, the blower pipe 34, or the outlet 37, the air supply unit 33 may be damaged. Also, if the air supply unit 33 is left running while scale has formed and clogged the connection between the blower pipe 34 and the electrolytic cell 30, or the outlet 37, the air supply unit 33 may be damaged. The switching unit 50d decides to stop the air supply unit 33 if, after a predetermined time has elapsed since stopping the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis, the airflow detection unit 39 detects that the airflow volume of the hypochlorous acid-containing air falls below the standard airflow volume. In that case, the switching unit 50d stops the air supply unit 33. Thus, damage to the air supply unit 33 can be prevented.

[0173] On the other hand, during the purification operation, the switching unit 50d determines whether to continue operating non-diaphragm electrolysis, first diaphragm electrolysis, and second diaphragm electrolysis if the airflow volume of the air containing hypochlorous acid detected by the airflow volume detection unit 39 is equal to or greater than the standard airflow volume. In that case, the switching unit 50d continues to supply the first current, the second current, and the third current.

[0174] Furthermore, if the switching unit 50d decides to continue the operation of non-diaphragm electrolysis, first diaphragm electrolysis, and second diaphragm electrolysis, it also decides to continue the operation of the water recovery unit 36. In that case, the switching unit 50d keeps the water recovery unit 36 ​​running. Furthermore, if the switching unit 50d decides to continue the operation of non-diaphragm electrolysis, first diaphragm electrolysis, and second diaphragm electrolysis, it also decides to continue the operation of the air supply unit 33. In that case, the switching unit 50d keeps the air supply unit 33 running.

[0175] The notification unit 50e of the current control unit 50 notifies the user of the air supply unit 33 when the airflow rate of the air containing hypochlorous acid detected by the airflow rate detection unit 39 falls below the standard airflow rate and the air supply unit 33 stops for a predetermined time. For example, the notification unit 50e performs notification by lighting or flashing a lamp (not shown) provided on the housing C. Alternatively, the notification unit 50e performs notification by displaying a message on a display (not shown) provided on the housing C. Furthermore, the notification unit 50e has a communication function and transmits to a server (not shown) that the air supply unit 33 has stopped for a predetermined time, and the server transmits to a terminal device that the air supply unit 33 has stopped for a predetermined time, causing the terminal device to perform notification by displaying a message. The terminal device is, for example, a smartphone and is held by the user.

[0176] The subject of the apparatus, system, or method in this disclosure comprises a computer. The functions of the subject of the apparatus, system, or method in this disclosure are realized by the computer executing a program. The computer comprises a processor as its main hardware component, which operates according to the program. The processor is of any type as long as it can realize its functions by executing the program. The processor consists of one or more electronic circuits, including semiconductor integrated circuits (ICs) or LSIs (Large Scale Integrations). Multiple electronic circuits may be integrated on one chip or provided on multiple chips. Multiple chips may be aggregated in one device or provided on multiple devices. The program is recorded on a non-temporary recording medium such as a ROM, optical disc, or hard disk drive that is readable by the computer. The program may be pre-stored on the recording medium or supplied to the recording medium via a wide-area communication network, including the Internet.

[0177] The operation of the air purification device 1 with the above configuration will now be explained. Figure 9 is a flowchart showing the switching procedure by the air purification device 1.

[0178] <Airflow detection → Electrolysis stopped → Airflow detection → Electrolysis resumed> The airflow detection unit 39 detects the airflow of the air containing hypochlorous acid (mixed air M) during the purification operation (step S10). If the airflow of the mixed air M containing hypochlorous acid is less than the standard airflow (Y in step S12), the current control unit 50 (switching unit 50d) stops the first diaphragm electrolysis and the second diaphragm electrolysis (step S14), and stops the non-diaphragm electrolysis (step S16). After a predetermined time has elapsed since stopping the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis, the airflow detection unit 39 detects the airflow of the air containing hypochlorous acid (mixed air M) (step S18). If the airflow of the mixed air M containing hypochlorous acid is equal to or greater than the standard airflow (step S20, N), the current control unit 50 (switching unit 50d) restarts the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis (step S22), continues to operate the water recovery unit 36 ​​(step S24), and continues to operate the air supply unit 33 (step S26).

[0179] <Air volume detection → Electrolysis stop → Air volume detection → Water recovery unit 36 ​​stop → Air supply unit 33 stop> On the other hand, after a predetermined time has elapsed since stopping the first diaphragm electrolysis, the second diaphragm electrolysis, and the non-diaphragm electrolysis in step S16, the airflow detection unit 39 detects the airflow of the air containing hypochlorous acid (mixed air M) (step S18). If the airflow of the mixed air M containing hypochlorous acid is less than the standard airflow (step S20, Y), the current control unit 50 (switching unit 50d) stops the water recovery unit 36 ​​(step S28) and stops the air supply unit 33 (step S30).

[0180] <Air volume detection → Purification operation continues> During the purification operation, the airflow detection unit 39 detects the airflow of the air containing hypochlorous acid (mixed air M) (step S10). If the airflow of the air containing hypochlorous acid is equal to or greater than the standard airflow (step S12, N), the current control unit 50 (switching unit 50d) continues to operate the non-diaphragm electrolysis, the first diaphragm electrolysis, and the second diaphragm electrolysis (step S32), the water recovery unit 36 ​​continues to operate (step S34), and the air supply unit 33 continues to operate (step S36).

[0181] As described above, the following effects can be enjoyed with the space purification device 1 according to the embodiment.

[0182] When the airflow of hypochlorous acid-containing air (mixed air M) released from the electrolytic cell 30 falls below the standard airflow rate, that is, when it falls below the standard airflow rate, at least the first and second diaphragm electrolysis processes among the non-diaphragm electrolysis, first diaphragm electrolysis, and second diaphragm electrolysis are stopped. As a result, the supply of chloride ions to the electrolytic cell 30 via the anion exchange membrane 41 and the supply of metal ions to the electrolytic cell 30 via the cation exchange membrane 42 are stopped. By stopping the supply of chloride ions, which are the source of hypochlorous acid, to the electrolytic cell 30, an upper limit is set on the total amount of hypochlorous acid gas that can be generated in the electrolytic cell 30, thereby suppressing the increase in the concentration of hypochlorous acid in the first aqueous solution L1. By suppressing the increase in the concentration of hypochlorous acid in the first aqueous solution L1, the release of high-concentration hypochlorous acid gas when the airflow of hypochlorous acid-containing air recovers to above the standard airflow rate is suppressed. Furthermore, by stopping the first and second diaphragm electrolysis, the airflow rate of the air containing hypochlorous acid falls below the standard airflow rate, and chloride ions and metal ions continue to be supplied under conditions where hypochlorous acid gas is not released from the first aqueous solution L1. This prevents the first aqueous solution L1 from becoming a strong acid or strong alkali outside the pH range of 5 to 10, thus suppressing premature deterioration of the anion exchange membrane 41 and cation exchange membrane 42.

[0183] In another process, if the airflow rate of hypochlorous acid-containing air (mixed air) released from the electrolytic cell 30 falls below the standard airflow rate, that is, if it falls below the standard airflow rate, the first diaphragm electrolysis and the second diaphragm electrolysis are stopped, as is the non-diaphragm electrolysis. This stops the generation of hypochlorous acid from chloride ions remaining in the electrolytic cell 30 at the time the first and second diaphragm electrolysis are stopped. Therefore, the concentration of hypochlorous acid in the electrolytic cell 30 can be suppressed. Consequently, the release of high-concentration hypochlorous acid gas when the airflow rate of hypochlorous acid-containing air recovers to above the standard airflow rate is suppressed. Furthermore, since non-diaphragm electrolysis is stopped when the airflow rate of hypochlorous acid-containing air released from the electrolytic cell 30 falls below the standard airflow rate, heat buildup in the electrolytic cell 30 is suppressed, and corrosion and deterioration of the electrodes (electrolytic cell-side anode 31, electrolytic cell-side cathode 32) can be suppressed. Furthermore, if the airflow of hypochlorous acid-containing air released from the electrolytic cell 30 falls below the standard airflow rate, the membrane-free electrolysis is stopped. This suppresses the increase in the concentration of hypochlorous acid in the electrolytic cell 30, thereby suppressing corrosion and deterioration of the ion exchange membrane (anion exchange membrane 41, cation exchange membrane 42) and the water recovery unit 36 ​​(for example, the cooling heat sink provided by the Peltier element). In addition, if the airflow of hypochlorous acid-containing air released from the electrolytic cell 30 falls below the standard airflow rate, the membrane-free electrolysis is stopped. This suppresses the consumption of water contained in the first aqueous solution L1 stored in the electrolytic cell 30. By suppressing water consumption, the exposure of the electrolytic cell-side anode 31 and electrolytic cell-side cathode 32 from the liquid surface S1 of the first aqueous solution L1 can be suppressed. Furthermore, if the airflow of hypochlorous acid-containing air released from the electrolytic cell 30 falls below the standard airflow rate, the non-diaphragm electrolysis is stopped. This prevents the first aqueous solution L1 from becoming strongly alkaline with a pH of 11 or higher, which could occur if non-diaphragm electrolysis were continued while the first and second diaphragm electrolysis were stopped. By suppressing the strong alkalinity of the first aqueous solution L1, the premature deterioration of the anion exchange membrane 41 and the cation exchange membrane 42 can be suppressed.

[0184] Furthermore, the water recovery unit 36 ​​is stopped when the airflow of hypochlorous acid-containing air (mixed air M) released from the electrolytic cell 30 falls below the standard airflow rate, thereby suppressing an increase in power consumption. Also, the air supply unit 33 is stopped when the airflow of hypochlorous acid-containing air released from the electrolytic cell 30 falls below the standard airflow rate, preventing damage to the air supply unit 33 when foreign matter clogs the air supply unit 33, the blower pipe 34, or the outlet 37. In addition, damage to the air supply unit 33 is prevented when scale builds up and clogs the connection between the blower pipe 34 and the electrolytic cell 30, or the outlet 37. Furthermore, the user is notified when the air supply unit 33 is stopped for a predetermined time, allowing the user to be aware of the operating status of the air purification device 1.

[0185] In the miniaturized air purification device 1, hydrogen-containing air generated in the chloride ion supply tank 10 flows through the first air passage 60 and the air supply unit 33 and is sent to the electrolytic cell 30, and the water recovery unit 36 ​​recovers the moisture contained in the air as a liquid and sends it to the electrolytic cell 30. This prevents the decrease in moisture content of the first aqueous solution L1 stored in the electrolytic cell 30 from decreasing even when electrolysis is repeatedly performed. In addition, oxygen-containing air generated in the metal ion supply tank 20 flows through the second air passage 62 and the air supply unit 33 and is sent to the electrolytic cell 30, and the water recovery unit 36 ​​recovers the moisture contained in the air as a liquid and sends it to the electrolytic cell 30. This prevents the decrease in moisture content of the first aqueous solution L1 stored in the electrolytic cell 30 from decreasing even when electrolysis is repeatedly performed in the miniaturized air purification device 1. Furthermore, since the first moisture-permeable waterproof membrane 64 is placed in the first air passage 60, it is possible to prevent the second aqueous solution L2 from the chloride ion supply tank 10 from flowing into the electrolytic cell 30. Furthermore, since the second moisture-permeable waterproof membrane 66 is placed inside the second air passage 62, it is possible to prevent the third aqueous solution L3 from the metal ion supply tank 20 from flowing into the electrolytic cell 30.

[0186] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit.

[0187] An overview of one aspect of this disclosure is as follows: (Item 1-1) An electrolytic cell that stores a first aqueous solution containing chloride ions and generates hypochlorous acid by diaphragm-free electrolysis of the first aqueous solution, A chloride ion supply tank stores a second aqueous solution containing a higher concentration of chloride ions than the first aqueous solution, 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. An airflow detection unit for detecting the airflow rate of air containing hypochlorous acid released from the electrolytic cell, Equipped with, Air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with the hypochlorous acid in a purification operation. During the aforementioned purification operation, if the airflow detected by the airflow detection unit falls below the standard airflow, at least the diaphragm electrolysis is stopped from the non-diaphragm electrolysis and the diaphragm electrolysis. Air purification device.

[0188] (Item 1-2) The diaphragm electrolysis in the chloride ion supply tank is the first diaphragm electrolysis. The air purification apparatus according to item 1-1, further comprising a metal ion supply tank for storing a third aqueous solution containing at least one metal ion selected from the group consisting of sodium ions, lithium ions, and potassium ions, and supplying the metal ion selected from the group contained in the third aqueous solution to the first aqueous solution by permeating a cation exchange membrane through a second diaphragm electrolysis.

[0189] (Item 1-3) It is equipped with a water recovery unit that recovers moisture contained in the circulating air as a liquid into the electrolytic cell, If, after a predetermined time has elapsed since the diaphragm electrolysis and the non-diaphragm electrolysis were stopped, the airflow detection unit detects that the airflow volume falls below the standard airflow volume, the water recovery unit is stopped. A space purification device as described in item 1-1 or 1-2.

[0190] (Items 1-4) The system includes an air supply unit that supplies air from the external space to the first aqueous solution stored in the electrolytic cell as bubbles, If, after a predetermined time has elapsed since the diaphragm electrolysis and the non-diaphragm electrolysis were stopped, the air supply unit is stopped if the airflow detected by the airflow detection unit falls below the standard airflow. The air purification device described in items 1-3.

[0191] (Items 1-5) If the aforementioned air supply unit stops for a predetermined period of time, the user will be notified of the stoppage. The air purification device described in items 1-4.

[0192] (Items 1-6) The second aqueous solution is a metal chloride aqueous solution containing metal ions and chloride ions, By performing the aforementioned diaphragm electrolysis, To compensate for the chloride ions contained in the first aqueous solution that have been reduced by the aforementioned non-diaphragm electrolysis, the chloride ions contained in the second aqueous solution stored in the supply tank are supplied to the first aqueous solution stored in the electrolytic cell by passing them through the anion exchange membrane. In the supply tank, metal ions contained in the second aqueous solution react with hydroxide ions generated by the diaphragm electrolysis to form a precipitate of metal hydroxide. The air purification device described in item 1-1.

[0193] (Item 2-1) An electrolytic cell that stores a first aqueous solution containing chloride ions and generates hypochlorous acid by diaphragm-free electrolysis of the first aqueous solution, A chloride ion supply tank stores a second aqueous solution containing a higher concentration of chloride ions than the first aqueous solution, 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 first air passage connects the upper space on the chloride ion supply tank side, which is formed above the liquid surface of the second aqueous solution, and the upper space on the electrolytic cell side, which is formed above the liquid surface of the first aqueous solution. A water recovery unit that recovers moisture contained in the air flowing from the electrolytic cell as a liquid and returns it to the electrolytic cell, Equipped with, Air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with the hypochlorous acid in a purification operation. In the purification operation described above, the gas generated in the chloride ion supply tank flows through the first air passage and the electrolytic cell and is released into the outside space together with the air. Air purification device.

[0194] (Item 2-2) The diaphragm electrolysis in the chloride ion supply tank is the first diaphragm electrolysis. A metal ion supply tank stores a third aqueous solution containing at least one metal ion selected from the group consisting of sodium ions, lithium ions, and potassium ions, and supplies the metal ion selected from the group contained in the third aqueous solution to the first aqueous solution by permeating a cation exchange membrane through a second diaphragm electrolysis, A second air passage connects the upper space on the metal ion supply tank side, which is formed above the liquid surface of the third aqueous solution, and the upper space on the electrolytic cell side. Furthermore, In the purification operation, the gas generated in the metal ion supply tank flows through the second air passage and the electrolytic cell and is released into the outside space together with the air. The air purification device described in item 2-1.

[0195] (Item 2-3) The second aqueous solution is a metal chloride aqueous solution containing metal ions and chloride ions, By performing the aforementioned diaphragm electrolysis, To compensate for the chloride ions contained in the first aqueous solution that have been reduced by the aforementioned non-diaphragm electrolysis, the chloride ions contained in the second aqueous solution stored in the supply tank are supplied to the first aqueous solution stored in the electrolytic cell by passing them through the anion exchange membrane. In the supply tank, metal ions contained in the second aqueous solution react with hydroxide ions generated by the diaphragm electrolysis to form a precipitate of metal hydroxide. A space purification device as described in item 2-1 or 2-2.

[0196] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing processes, and that such modifications are also within the scope of the present disclosure. [Explanation of Symbols]

[0197] 1. Air purification device, 10. Chloride ion supply tank, 11. Chloride ion supply tank side cathode, 12. Chloride ion supply tank side internal space, 20. Metal ion supply tank, 21. Metal ion supply tank side anode, 22. Metal ion supply tank side internal space, 30. Electrolytic cell, 31. Electrolytic cell side anode, 32. Electrolytic cell side cathode, 33. Air supply unit, 34. Air blower pipe, 35. Electrolytic cell side internal space, 36. Water recovery unit, 37. Discharge port, 38. Water level detection unit, 39. Air volume detection unit, 41. Anion exchange membrane, 42. Cation exchange membrane, 50. Current control unit, 50a. Voltage acquisition unit, 50b. Calculation unit, 50c. Estimation unit, 50d. Switching unit, 50e. Notification unit, 51, 52, 53, 54. Wiring, 60 1st air passage, 62 2nd air passage, 64 1st moisture-permeable waterproof membrane, 66 2nd moisture-permeable waterproof membrane, A air flow path, B bubble, C housing, E1 1st diaphragm electrolytic part, E2a,E2b 2nd diaphragm electrolytic part, E3 non-diaphragm electrolytic part, L1 1st aqueous solution, L2 2nd aqueous solution, L3 3rd aqueous solution, M mixed air, R external space, S1,S2,S3 liquid level.

Claims

1. An electrolytic cell that stores a first aqueous solution containing chloride ions and produces hypochlorous acid by diaphragm-free electrolysis of the first aqueous solution, A chloride ion supply tank stores a second aqueous solution containing a higher concentration of chloride ions than the first aqueous solution, 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 first air passage connects the upper space on the chloride ion supply tank side, which is formed above the liquid surface of the second aqueous solution, and the upper space on the electrolytic cell side, which is formed above the liquid surface of the first aqueous solution. A water recovery unit that recovers moisture contained in the air flowing from the electrolytic cell as a liquid and returns it to the electrolytic cell, Equipped with, Air introduced from the outside space flows through the electrolytic cell and is released into the outside space together with the hypochlorous acid in a purification operation. In the purification operation described above, the gas generated in the chloride ion supply tank flows through the first air passage and the electrolytic cell and is released into the outside space together with the air. Air purification device.

2. The diaphragm electrolysis in the chloride ion supply tank is the first diaphragm electrolysis. A metal ion supply tank stores a third aqueous solution containing at least one metal ion selected from the group consisting of sodium ions, lithium ions, and potassium ions, and supplies the metal ion selected from the group contained in the third aqueous solution to the first aqueous solution by permeating a cation exchange membrane through a second diaphragm electrolysis, A second air passage connects the upper space on the metal ion supply tank side, which is formed above the liquid surface of the third aqueous solution, and the upper space on the electrolytic cell side. Furthermore, In the purification operation, the gas generated in the metal ion supply tank flows through the second air passage and the electrolytic cell and is released into the outside space together with the air. The air purification device according to claim 1.

3. The second aqueous solution is a metal chloride aqueous solution containing metal ions and chloride ions, By performing the aforementioned diaphragm electrolysis, To compensate for the chloride ions contained in the first aqueous solution that have been reduced by the aforementioned non-diaphragm electrolysis, the chloride ions contained in the second aqueous solution stored in the supply tank are supplied to the first aqueous solution stored in the electrolytic cell by passing them through the anion exchange membrane. In the supply tank, metal ions contained in the second aqueous solution react with hydroxide ions generated by the diaphragm electrolysis to form a precipitate of metal hydroxide. The air purification device according to claim 1 or 2.

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