Space purification device

Abstract

This space purification device (1) comprises: an electrolysis tank (10) that holds and electrolyzes a first aqueous solution (L1) containing chloride ions (Cl-) and that generates hypochlorous acid; a chloride ion supply tank (20) that holds a second aqueous solution (L2) containing Cl-, that causes the Cl- contained in the second aqueous solution (L2) to permeate through an anion exchange membrane (41) by membrane electrolysis, and that supplies the Cl- to the first aqueous solution (L1); and a high-concentration chloride aqueous solution supply tank (30) that holds a high-concentration chloride aqueous solution (HC) containing Cl- at a higher concentration than in the second aqueous solution (L2) and that supplies the high-concentration chloride aqueous solution (HC) to the second aqueous solution (L2). When supplementing the Cl- contained in the second aqueous solution (L2), which has been reduced by the membrane electrolysis, the high-concentration chloride aqueous solution (HC) is supplied to the second aqueous solution (L2) such that the concentration of Cl- contained in the second aqueous solution (L2) is maintained within a range of prescribed concentration differences relative to the concentration of Cl- in the first aqueous solution (L1).

Description

Space Purification Device

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

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

[0003] Japanese Patent Application Laid-Open No. 2019-174032

[0004] When a conventional space purification device is downsized, the tank that stores the aqueous solution used for electrolysis also becomes smaller. This downsizing of the tank reduces the amount of aqueous solution that can be stored compared to conventional space purification devices. Therefore, when electrolysis is repeatedly performed in a downsized space purification device, the chloride ion concentration in the aqueous solution tends to decrease, resulting in an unstable amount of hypochlorous acid generated.

[0005] The present disclosure provides a space purification device that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from outside.

[0006] The space purification device according to the present disclosure includes an electrolytic cell that stores a first aqueous solution containing chloride ions and electrolyzes the first aqueous solution to produce hypochlorous acid, a chloride ion supply tank that stores a second aqueous solution containing chloride ions and supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by permeating an anion exchange membrane using diaphragm electrolysis, and a high-concentration chloride aqueous solution supply tank that stores a high-concentration chloride aqueous solution containing a higher chloride ion concentration than the second aqueous solution and supplies the high-concentration chloride aqueous solution to the second aqueous solution. When replacing the chloride ions contained in the second aqueous solution reduced by diaphragm electrolysis, the high-concentration chloride aqueous solution is supplied to the second aqueous solution so that the concentration of chloride ions contained in the second aqueous solution is maintained within a predetermined concentration difference range relative to the chloride ion concentration of the first aqueous solution, and a purification operation is performed in which air introduced from an external space flows through the electrolytic cell and is released into the external space together with hypochlorous acid.

[0007] The present disclosure provides a space purification device that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from the outside.

[0008] FIG. 1 is a front cross-sectional view showing a space purification device according to a first embodiment. FIG. 2 is a block diagram showing a current control unit according to the first embodiment. FIG. 3 is a partial cross-sectional plan view taken along line III-III in FIG. 1 , showing a first example of each electrolysis unit included in the space purification device. FIG. 4 is a partial cross-sectional plan view taken along line III-III in FIG. 1 , showing a second example of each electrolysis unit included in the space purification device. FIG. 5 is a list of chemical reactions occurring in the first aqueous solution stored in the first supply tank of the first diaphragm electrolysis unit and in the third aqueous solution stored in the electrolysis tank. FIG. 6 is a list of chemical reactions occurring in the first aqueous solution stored in the first supply tank of the second diaphragm electrolysis unit and in the second aqueous solution stored in the second supply tank. FIG. 7 is a list of chemical reactions occurring in the second aqueous solution stored in the second supply tank of the second diaphragm electrolysis unit and in the third aqueous solution stored in the electrolysis tank. FIG. 8 is a list of reaction formulas that occur in the third aqueous solution stored in the electrolytic cell of the membraneless electrolysis section.

[0009] Specific embodiments of the present disclosure will be described in detail below with reference to the drawings.

[0010] The xyz coordinates shown in the drawings are for the convenience of explaining the positional relationships of the components. Unless otherwise specified, the positive side of the z axis is vertically upward. The xy plane is a horizontal plane, and is common to all drawings.

[0011] 1 is a front cross-sectional view showing a space purification device 1 according to embodiment 1. The space purification device 1 performs electrolysis on a first aqueous solution L1 containing chloride ions in an electrolytic cell 10 (described later) to generate and volatilize hypochlorous acid. The space purification device 1 removes bacteria, fungi, viruses, odors, and the like contained in the air in the external space R of the space purification device 1 by causing the volatilized hypochlorous acid to flow into the external space R of the housing C that constitutes the space purification device 1.

[0012] The space purification device 1 is installed indoors. The installation location of the space purification device 1 is preferably a location where air flow can occur. More specifically, the installation location of the space purification device 1 is indoors, and more specific locations include, for example, inside a bathroom heater / dryer, inside an air conditioner (i.e., an air conditioner), around an electric fan, around a circulator, around a ceiling fan, inside a humidifier, inside an air purifier, and on a desk.

[0013] 1 , the space purification device 1 includes a housing C, an electrolytic cell 10, a chloride ion supply tank 20, a high-concentration chloride aqueous solution supply tank 30, an anion exchange membrane 41, and a current control unit 60. The space purification device 1 may further include a cation exchange membrane 42 and a metal ion supply tank 50. In this embodiment, an example including the cation exchange membrane 42 and the metal ion supply tank 50 will be described.

[0014] The housing C houses the electrolytic cell 10, the chloride ion supply tank 20, the high-concentration chloride aqueous solution supply tank 30, the metal ion supply tank 50, the anion exchange membrane 41, the cation exchange membrane 42, and the current control unit 60. That is, the space purification device 1 may be an integrated unit formed by the housing C. The shape of the housing C can be changed appropriately depending on the location where the space purification device 1 is installed, and may be, for example, a rectangular parallelepiped or cylindrical shape. The space purification device 1 has a small size that can be stored inside an air conditioner, for example, and when the housing C is rectangular, it is approximately 10 cm x 7 cm x 4 cm.

[0015] The volumes of the electrolytic cell 10, chloride ion supply cell 20, high-concentration chloride aqueous solution supply cell 30, and metal ion supply cell 50 assuming continuous use for eight hours every day for one year will be described below. For example, the volume of the chloride ion supply cell 20 is preferably about eight times or more the volume of the electrolytic cell 10. Furthermore, for example, the volume ratio of the chloride ion supply cell 20 to the high-concentration chloride aqueous solution supply cell 30 may be 2:3. Furthermore, for example, the volume of the metal ion supply cell 50 is preferably about four times or more the volume of the electrolytic cell 10. By setting such a volume ratio, the chloride ion supply cell 20 and the high-concentration chloride aqueous solution supply cell 30 can store the second aqueous solution L2 and the high-concentration chloride aqueous solution HC containing sufficient amounts of chloride ions to be supplied to the first aqueous solution L1 of the electrolytic cell 10. In addition, the metal ion supply tank 50 can store a third aqueous solution L3 containing a sufficient amount of metal ions (metal ions selected from the group consisting of sodium ions, lithium ions, and potassium ions, described below) required to be supplied to the first aqueous solution L1 of the electrolytic tank 10.

[0016] Therefore, chloride ions can be stably supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic tank 10. Similarly, a necessary amount of metal ions can be stably supplied from the third aqueous solution L3 stored in the metal ion supply tank 50 to the first aqueous solution L1 stored in the electrolytic tank 10. The amount of the first aqueous solution L1 stored in the electrolytic tank 10 is, for example, about 2 mL to 10 mL.

[0017] The electrolytic cell 10, chloride ion supply cell 20, high-concentration chloride aqueous solution supply cell 30, and metal ion supply cell 50 are arranged in this order from the negative side of the x-axis in a front view: metal ion supply cell 50, electrolytic cell 10, chloride ion supply cell 20, and high-concentration chloride aqueous solution supply cell 30. An anion exchange membrane 41 is arranged between the electrolytic cell 10 and the chloride ion supply cell 20. In addition, a cation exchange membrane 42 is arranged between the electrolytic cell 10 and the metal ion supply cell 50. For example, if the surface of the electrolytic cell 10 facing the chloride ion supply cell 20 and the surface of the chloride ion supply cell 20 facing the electrolytic cell 10 each have a shape (frame-like shape) with an opening, the anion exchange membrane 41 may be arranged so as to be fitted into the opening. Similarly, when the surface of the electrolytic cell 10 facing the metal ion supply cell 50 and the surface of the metal ion supply cell 50 facing the electrolytic cell 10 each have an opening (a frame-shaped member), the cation exchange membrane 42 may be disposed so as to be fitted into the opening. The current control unit 60 is disposed at any position within the housing C.

[0018] [Electrolytic Cell 10] The electrolytic cell 10 is a cell for storing a first aqueous solution L1 containing chloride ions. The electrolytic cell 10 has, for example, a box-like shape. FIG. 1 shows a state in which the first aqueous solution L1 is stored in the electrolytic cell 10. The first aqueous solution L1 is, for example, an aqueous solution in which an electrically conductive electrolyte is dissolved, and specifically, a dilute chloride aqueous solution having a predetermined chloride ion concentration. More specifically, the first aqueous solution L1 is, for example, a dilute sodium chloride aqueous solution or a dilute potassium chloride aqueous solution.

[0019] The "predetermined chloride ion concentration" of the first aqueous solution L1 includes both a chloride ion concentration having a predetermined numerical range and a chloride ion concentration having a predetermined numerical value. More specifically, the chloride ion concentration of the first aqueous solution L1 may be, for example, 1 g / L to 50 g / L, or may be 10 g / L. In other words, the mass percent concentration of the dilute sodium chloride aqueous solution or the dilute potassium chloride aqueous solution may be, for example, 0.1% to 5%, or may be 5%. By setting the predetermined chloride ion concentration to this numerical range or numerical value, it is possible to generate hypochlorous acid necessary for space purification while simultaneously suppressing the generation of chlorine, which may be generated.

[0020] The electrolytic cell 10 includes an electrolytic cell-side anode 11, an electrolytic cell-side cathode 12, an air supply unit 13, an air duct 14, an electrolytic cell-side internal space 15, a water recovery unit 16, and an outlet 17. The electrolytic cell 10 may further include a water level detection unit 18.

[0021] The electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 are a pair of electrodes used for electrolyzing the first aqueous solution L1. The electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 are each inserted from the outside to the inside of the electrolytic cell 10. The electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 each have a plate-like shape. Examples of plate-like shapes include rectangular and oblong shapes.

[0022] Insoluble electrodes may be used as the electrolytic cell side anode 11 and the electrolytic cell side cathode 12. 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] No diaphragm such as an ion exchange membrane is provided between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. That is, the electrolysis of the first aqueous solution L1 performed using the pair of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 is diaphragm-less electrolysis. Hypochlorous acid, which is used for space purification of the external space R, is produced by the diaphragm-less electrolysis of the first aqueous solution L1 performed using the pair of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12.

[0024] The yz plane on the negative side of the x-axis of the electrolytic cell-side anode 11 and the yz plane on the positive side of the x-axis of the electrolytic cell-side cathode 12 are arranged opposite each other. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. Because the electric field is generated uniformly, the current between the two electrodes is also distributed uniformly. Therefore, deterioration of the catalytic layer on the surface of each electrode occurs uniformly, and therefore, even when electrolysis is performed repeatedly, uneven deterioration of the catalytic layer on the surface of each electrode due to an uneven electric field can be suppressed. Therefore, a decrease in electrolysis efficiency can be suppressed.

[0025] Air supply unit 13 is a blower or a predetermined opening that introduces air from external space R into electrolytic cell 10. When air supply unit 13 is an opening, it is preferably placed at any position that allows air to circulate through the opening, such as a circulator, electric fan, or ceiling fan placed inside a bathroom heater / dryer, inside an air conditioner, or outside space purification device 1.

[0026] The air duct 14 is a tubular member that connects the air supply unit 13 and the electrolytic cell 10. One end of the air supply unit 13 is disposed on the external space R side, and the other end of the air supply unit 13 is connected to the air duct 14. One end of the air duct 14 is connected to the air supply unit 13, and the other end of the air duct 14 is connected to the electrolytic cell 10. The end of the air duct 14 that is connected to the electrolytic cell 10 is disposed in the electrolytic cell 10 so as to be located below the liquid level S1 of the first aqueous solution L1 stored in the electrolytic cell 10 (on the negative side of the z-axis).

[0027] The air supply unit 13 supplies air from the external space R into the first aqueous solution L1 stored in the electrolytic cell 10 via the air blower 14. The air introduced into the first aqueous solution L1 via the air supply unit 13 and the air blower 14 is released as bubbles B.

[0028] The electrolytic cell-side internal space 15 is an upper space (space on the positive z-axis side) formed above the liquid level S1 of the first aqueous solution L1 when the first aqueous solution L1 is stored in the electrolytic cell 10. In other words, the first aqueous solution L1 is not stored up to the internal upper surface of the electrolytic cell 10 (xy plane on the positive z-axis side), and the electrolytic cell 10 has the electrolytic cell-side internal space 15.

[0029] The water recovery unit 16 is a component that flows through the interior of the space purification device 1 and recovers moisture contained in the air released from the electrolytic cell 10 to the external space R as a liquid and returns it to the electrolytic cell 10. The water recovery unit 16 is, for example, a Peltier element that can cool the moisture contained in the air, condense it, and turn it into water droplets. In order to recover moisture contained in the air flowing through the interior of the space purification device 1, the water recovery unit 16 may be disposed at the discharge port 17 through which the air passes when it is released to the external space R. When the water recovery unit 16 is disposed at the discharge port 17, it is possible to efficiently recover moisture contained in the air that has flowed through the interior of the space purification device 1. The water recovery unit 16 may be disposed at any position in the electrolytic cell-side internal space 15.

[0030] The discharge port 17 is an opening for discharging mixed air M, which is a mixture of air flowing in from the air supply unit 13 and hypochlorous acid generated from the first aqueous solution L1 by diaphragm-less electrolysis, into the external space R of the casing C. In FIG. 1 , the discharge port 17 is provided on the top surface of the electrolytic cell 10 (the x-y plane on the positive side of the z-axis) as an example, but it may be located above the liquid level S1 of the first aqueous solution L1. The shape of the discharge port 17 is tubular, and may be, for example, a cylindrical or rectangular tubular shape. When the top surface of the electrolytic cell 10 (the surface on the positive side of the z-axis) is close to the ceiling surface of the casing C, the discharge port 17 may be a hole-like opening provided in a part of the top surface of the electrolytic cell 10. Alternatively, the discharge port 17 and the top surface of the casing C (the x-y plane on the positive side of the z-axis) may be integrally formed.

[0031] The outlet 17 may be provided with an openable or detachable lid (not shown). The lid may be configured to be closed when the space purification device 1 is transported, moved, or installed, and to be opened or detached when the space purification device 1 is used.

[0032] The space purification device 1 according to this embodiment performs a purification operation in which air introduced from the external space R flows through the electrolytic cell 10 and is released together with hypochlorous acid into the external space R. The air flow path A indicated by the outline arrow in Fig. 1 is a series of paths along which air supplied from the external space R to the space purification device 1 flows through the electrolytic cell 10 and is released as mixed air M containing hypochlorous acid into the external space R. That is, the air flow path A indicates the flow of air from the external space R, the air supply unit 13, the air duct 14, the first aqueous solution L1 stored in the electrolytic cell 10, the electrolytic cell-side internal space 15, the water recovery unit 16, the discharge port 17, and to the external space R.

[0033] More specifically, in the air flow path A, as shown in Fig. 1 , air is released as bubbles B from the external space R via the air supply unit 13 and the air blower duct 14 into the first aqueous solution L1 stored in the electrolytic cell 10. In other words, bubbles B are generated by bubbling the first aqueous solution L1 with air introduced from the external space R. The bubbles B are mixed with hypochlorous acid generated by the diaphragm-less electrolysis of the first aqueous solution L1 to form mixed air M.

[0034] Here, the hypochlorous acid produced by the membrane-less 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 electrolytic cell-side internal space 15. The hypochlorous acid dissolved in the first aqueous solution L1 is mixed with bubbles B and is released as mixed air M from the discharge port 17 into the external space R via the water recovery unit 16. The hypochlorous acid gas that has volatilized and gasified into the electrolytic cell-side internal space 15 is mixed with the bubbles B mixed with hypochlorous acid and is released as mixed air M from the discharge port 17 into the external space R via the water recovery unit 16.

[0035] By generating bubbles B in the first aqueous solution L1 by bubbling, the bubbles B come into gas-liquid contact with the hypochlorous acid as they rise toward the liquid surface S1 due to buoyancy, and the hypochlorous acid can be incorporated into the bubbles B. In other words, compared to gas-liquid contact between air and the liquid surface S1 of the first aqueous solution L1, gas-liquid contact resulting from the generation of bubbles B in the first aqueous solution L1 by bubbling allows more hypochlorous acid to be incorporated into the bubbles B. In other words, mixed air M containing more hypochlorous acid can be released into the external space R. The mixed air M contains moisture that has evaporated from the first aqueous solution L1, but the moisture contained in the mixed air M is recovered by the water recovery unit 16 and returned to the first aqueous solution L1 as water droplets.

[0036] The mixed air M containing hypochlorous acid is released from the outlet 17 into the external space R of the space purification device 1 to purify the external space R. That is, the mixed air M containing hypochlorous acid removes bacteria, fungi, viruses, odors, and the like contained in the air in the external space R of the housing C.

[0037] The electrolytic cell 10 may further include a water level detector 18 .

[0038] The water level detector 18 detects the position of the liquid level S1 of the first aqueous solution L1. The water level detector 18 is, for example, a water level sensor. The water level detector 18 is disposed above (on the positive z-axis side) the upper ends (on the positive z-axis side) of at least the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12.

[0039] When the space purification device 1 is equipped with a water level detection unit 18, the water recovery unit 16 supplies water to the electrolytic cell 10 based on the position of the liquid level S1 detected by the water level detection unit 18. More specifically, the water recovery unit 16 supplies water to the electrolytic cell 10 so that the water level does not fall below the upper ends (portions on the positive side of the z-axis) of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. Furthermore, the water recovery unit 16 supplies water to the electrolytic cell 10 so that the water level does not fall below the upper end (portion on the positive side of the z-axis) of the air blower duct 14 connected to the electrolytic cell 10.

[0040] When the space purification device 1 is equipped with the water recovery unit 16 and the water level detection unit 18, the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 can be maintained immersed in the first aqueous solution L1. Therefore, by providing the water level detection unit 18, exposure of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 to air due to a decrease in the first aqueous solution L1 can be suppressed, and the electrolysis efficiency of the diaphragm-less electrolysis can be maintained. Note that the chloride ion supply tank 20 and the metal ion supply tank 50 may also be equipped with a water recovery unit and a water level detection unit similar to those of the electrolytic cell 10.

[0041] [Chloride ion supply tank 20] The chloride ion supply tank 20 is a tank for storing the second aqueous solution L2 containing chloride ions and for supplying the chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1. Fig. 1 shows a state in which the second aqueous solution L2 is stored in the chloride ion supply tank 20.

[0042] To ensure safety in the event of leakage, the solute of the second aqueous solution L2 is preferably a substance classified under the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) as being as safe as sodium chloride. Specifically, the second aqueous solution L2 is a metal chloride aqueous solution containing metal ions and chloride ions. When the second aqueous solution L2 is subjected to the first membrane electrolysis described below, the metal ions contained in the second aqueous solution L2 react with the hydroxide ions generated by the first membrane electrolysis to form a metal hydroxide precipitate.

[0043] When a magnesium chloride aqueous solution is used as the second aqueous solution L2, the mass percentage concentration of the magnesium chloride aqueous solution is, for example, 1% to 10%. As an example, when the second aqueous solution L2 is a magnesium chloride aqueous solution, by performing the first diaphragm electrolysis described below, magnesium ions contained in the magnesium chloride aqueous solution react with hydroxide ions generated by the first diaphragm electrolysis to form a precipitate of magnesium hydroxide. Note that the "precipitate" of magnesium hydroxide includes hard sand, colloid, slurry, and gel forms, as well as a cloudy aqueous solution.

[0044] The chloride ion supply tank 20 includes a chloride ion supply tank side cathode 21 (referred to as the “supply tank side cathode” in the claims), a chloride ion supply tank side internal space 22 , and a first outlet 23 .

[0045] The chloride ion supply tank side cathode 21 is inserted from the outside to the inside of the chloride ion supply tank 20. The chloride ion supply tank side cathode 21 has a plate-like shape. Plate shapes include rectangular and oblong shapes. The chloride ion supply tank side cathode 21 is paired with the electrolytic cell side anode 11 described below and is used in first membrane-with-diaphragm electrolysis via an anion exchange membrane 41. Details of the first membrane-with-diaphragm electrolysis will be described later with reference to FIG. 2 . Chloride ions are supplied from the second aqueous solution L2 to the first aqueous solution L1 by the first membrane-with-diaphragm electrolysis of the second aqueous solution L2 performed using the pair of the chloride ion supply tank side cathode 21 and the electrolytic cell side anode 11.

[0046] An insoluble electrode may be used as the chloride ion supply tank side cathode 21. 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.

[0047] The chloride ion supply tank-side internal space 22 is an upper space (space on the positive z-axis side) formed above the liquid level S2 of the second aqueous solution L2 when the second aqueous solution L2 is stored in the chloride ion supply tank 20. In other words, the second aqueous solution L2 is not stored up to the internal upper surface (xy plane on the positive z-axis side) of the chloride ion supply tank 20, and the chloride ion supply tank 20 has the chloride ion supply tank-side internal space 22.

[0048] The first outlet 23 is an opening for discharging hydrogen gas generated by the first diaphragm electrolysis of the second aqueous solution L2 to the external space R of the casing C. The first outlet 23 is, for example, a check valve. When a check valve is used as the first outlet 23, hydrogen gas inside the chloride ion supply tank 20 is discharged to the external space R, but the inflow of gases such as air from the external space R can be suppressed. When the diaphragm electrolysis of the second aqueous solution L2 is repeated, hydrogen gas accumulates in the chloride ion supply tank-side internal space 22, and the internal pressure of the chloride ion supply tank 20 increases. This pressure opens the check valve of the first outlet 23, and the hydrogen gas is discharged to the external space R of the chloride ion supply tank 20.

[0049] [High-concentration chloride aqueous solution supply tank 30] The high-concentration chloride aqueous solution supply tank 30 is a tank for storing a high-concentration chloride aqueous solution HC containing chloride ions at a higher concentration than the second aqueous solution L2, and for supplying the high-concentration chloride aqueous solution HC to the second aqueous solution L2 stored in the chloride ion supply tank 20.

[0050] The chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10 by the first diaphragm electrolysis described below, and are reduced. The high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 so that the concentration of chloride ions contained in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the concentration of chloride ions contained in the first aqueous solution L1. If the difference between the chloride ion concentrations of the first aqueous solution L1 and the second aqueous solution L2 (i.e., the concentration difference) is large, there is a risk that the water of the first aqueous solution L1 or the second aqueous solution L2 will move to one side through the anion exchange membrane 41 due to osmotic pressure. Therefore, the "predetermined concentration difference," which is the difference in concentration between the chloride ions in the first aqueous solution L1 and the second aqueous solution, is a concentration difference within a range in which water movement through the anion exchange membrane 41 is unlikely to occur. "Water movement is unlikely to occur" means that even if the space purification device 1 according to this embodiment is used continuously for eight hours every day for one year, water movement can be suppressed to the extent that water does not overflow from either the electrolytic cell 10 or the chloride ion supply cell 20.

[0051] The high-concentration chloride aqueous solution HC is a solution obtained by increasing the concentration of the second aqueous solution L2. When the high-concentration chloride aqueous solution HC is a high-concentration magnesium chloride aqueous solution, the mass percent concentration is, for example, about 25 to 35%. Preferably, the high-concentration chloride aqueous solution HC is a saturated magnesium chloride aqueous solution.

[0052] The high-concentration chloride aqueous solution supply tank 30 includes a delivery unit 31. The delivery unit 31 delivers the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 to the chloride ion supply tank 20. The delivery unit 31 is, for example, a liquid pump. The delivery unit 31 is arranged between the chloride ion supply tank 20 and the high-concentration chloride aqueous solution supply tank 30. The delivery unit 31 includes a suction-side tube 32 that sucks in the high-concentration chloride aqueous solution HC and a drip-side tube 33 that is arranged on the chloride ion supply tank 20 side and drips the high-concentration chloride aqueous solution HC sucked from the high-concentration chloride aqueous solution supply tank 30 into the second aqueous solution L2. The flow of the high-concentration chloride aqueous solution HC sucked into the suction-side tube 32 (positive direction of the z-axis) and the flow of the high-concentration chloride aqueous solution HC dripped into the second aqueous solution L2 by the drip-side tube 33 (negative direction of the z-axis) are indicated by thin white arrows.

[0053] [Metal ion supply tank 50] The metal ion supply tank 50 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. Fig. 1 shows a state in which the third aqueous solution L3 is stored in the metal ion supply tank 50.

[0054] To ensure safety in the event of leakage, the solute of the third aqueous solution L3 is preferably a substance classified under the GHS as being as safe as sodium chloride. Specifically, the third aqueous solution L3 is a metal compound aqueous solution 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 types selected from the group consisting of sodium ions, lithium ions, and potassium ions, or a combination of two or three types.

[0055] More specifically, the third aqueous solution L3 is preferably disodium hydrogen phosphate (Na ２ HPO ４) aqueous solution, sodium bicarbonate (NaHCO ３ ) aqueous solution, lithium carbonate (LiCO ３ ) aqueous solution, potassium carbonate (K ２ CO ３ ) aqueous solutions. That is, the third aqueous solution L3 may be one or more aqueous 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, or a combination of two, three, or four aqueous solutions. 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. Note that "saturated" in this specification also includes cases where the solute does not dissolve in water and precipitates. More specific mass percent concentrations of each aqueous solution are as shown below. Note that the mass percent concentrations of each aqueous solution shown below include both the concentration in the initial state when use of the space purification device 1 begins and the concentration when the concentration of the third aqueous solution L3 decreases as the space purification device 1 is used.

[0056] When a disodium hydrogen phosphate aqueous solution is used as the third aqueous solution L3, the mass percent concentration of the disodium hydrogen phosphate aqueous solution is, for example, 1% to 8%.

[0057] When an aqueous solution of sodium bicarbonate is used as the third aqueous solution L3, the mass percent concentration of the aqueous solution of sodium bicarbonate is, for example, 1% to 10%.

[0058] When an aqueous lithium carbonate solution is used as the third aqueous solution L3, the mass percent concentration of the aqueous lithium carbonate solution is, for example, 1% to 2%.

[0059] When an aqueous potassium carbonate solution is used as the third aqueous solution L3, the mass percent concentration of the aqueous potassium carbonate solution is, for example, 1% to 112%.

[0060] When a combination of two aqueous solutions selected from the group consisting of disodium hydrogen phosphate aqueous solution, sodium hydrogen carbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution is used as the third aqueous solution L3, the mass percentage concentration of the mixed solution is, for example, 1% to 122%.

[0061] When a combination of three aqueous solutions selected from the group consisting of disodium hydrogen phosphate aqueous solution, sodium hydrogen carbonate aqueous solution, lithium carbonate aqueous solution, and potassium carbonate aqueous solution is used as the third aqueous solution L3, the mass percentage concentration of the mixed solution is, for example, 1% to 130%.

[0062] When a mixed solution of a combination of four aqueous solutions, disodium hydrogen phosphate, sodium bicarbonate, lithium carbonate, and potassium carbonate, is used as the third aqueous solution L3, the mass percentage concentration of the mixed solution is, for example, 1% to 132%.

[0063] The metal ion supply tank 50 includes a metal ion supply tank side anode 51 , a metal ion supply tank side internal space 52 , and a second outlet 53 .

[0064] The metal ion supply tank side anode 51 is inserted from the outside to the inside of the metal ion supply tank 50. The metal ion supply tank side anode 51 has a plate-like shape. Plate-like shapes include rectangular and oblong shapes. The metal ion supply tank side anode 51 is paired with the electrolytic cell side cathode 12 described below and is used in second membrane-with-diaphragm electrolysis via a cation exchange membrane 42. Details of the second membrane-with-diaphragm electrolysis will be described later with reference to FIG. 2 . Metal ions are supplied from the third aqueous solution L3 to the first aqueous solution L1 by the second membrane-with-diaphragm electrolysis of the third aqueous solution L3 performed using the pair of the metal ion supply tank side anode 51 and the electrolytic cell side cathode 12.

[0065] An insoluble electrode may be used as the metal ion supply tank side anode 51. 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.

[0066] The metal ion supply tank-side internal space 52 is an upper space (space on the positive z-axis side) formed above the liquid level S3 of the third aqueous solution L3 when the third aqueous solution L3 is stored in the metal ion supply tank 50. In other words, the third aqueous solution L3 is not stored up to the internal upper surface (xy plane on the positive z-axis side) of the metal ion supply tank 50, and the metal ion supply tank 50 has the metal ion supply tank-side internal space 52.

[0067] The second outlet 53 is an opening for discharging oxygen generated by the second diaphragm electrolysis of the third aqueous solution L3 to the external space R of the casing C. The second outlet 53 is, for example, a check valve. When a check valve is used as the second outlet 53, oxygen inside the metal ion supply tank 50 is discharged to the external space R, but the inflow of gases such as air from the external space R can be suppressed. When the diaphragm electrolysis of the third aqueous solution L3 is repeated, oxygen accumulates in the metal ion supply tank-side internal space 52, and the internal pressure of the metal ion supply tank 50 increases. This pressure opens the check valve of the second outlet 53, and oxygen is discharged into the external space R of the metal ion supply tank 50.

[0068] [Anion Exchange Membrane 41] The anion exchange membrane 41 is a membranous member that connects the electrolytic cell 10 and the chloride ion supply cell 20 in a manner that allows anions to pass therethrough, based on a voltage applied between the electrolytic cell 10 and the chloride ion supply cell 20. More specifically, when a voltage is applied between the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21, first membrane-with-diaphragm electrolysis is performed via the anion exchange membrane 41. By the first membrane-with-diaphragm electrolysis using the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21, chloride ions contained in the second aqueous solution L2 permeate the anion exchange membrane 41 and are supplied to the first aqueous solution L1 (indicated by a thick black arrow in the negative direction of the x-axis).

[0069] The anion exchange membrane 41 in this embodiment is not a type of membrane through which anions permeate due to osmotic pressure 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 permeate the anion exchange membrane 41 and are supplied to the first aqueous solution L1 by first membrane-with-diaphragm electrolysis using the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21, magnesium ions, which are cations, do not permeate the anion exchange membrane 41. The anion exchange membrane 41 is, for example, a hydrocarbon-based anion exchange membrane, and includes membranes that have monovalent anion-selective permeability, alkali resistance, and high-temperature resistance.

[0070] The plane of the electrolytic cell-side anode 11 on the anion exchange membrane 41 side (the yz plane on the positive side of the x-axis) and the plane of the chloride ion supply tank-side cathode 21 on the anion exchange membrane 41 side (the yz plane on the negative side of the x-axis) are arranged opposite each other. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side anode 11 and the chloride ion supply tank-side cathode 21. Because the electric field is generated uniformly, the current between the two electrodes is also distributed uniformly. Therefore, deterioration of the catalytic layer on the surface of each electrode occurs uniformly, and therefore, even when electrolysis is performed repeatedly, uneven deterioration of the catalytic layer on the surface of each electrode due to an uneven electric field can be suppressed. Therefore, a decrease in electrolysis efficiency can be suppressed.

[0071] Furthermore, the electrolytic cell side anode 11 and the chloride ion supply tank side cathode 21 are each disposed close to the anion exchange membrane 41. In this specification, "close to" includes both a state in which the electrolytic cell side anode 11 and the chloride ion supply tank side cathode 21 are close to the anion exchange membrane 41 with a predetermined gap between them, and a state in which the electrolytic cell side anode 11 and the chloride ion supply tank side cathode 21 are in contact with the anion exchange membrane 41.

[0072] [Cation exchange membrane 42] The cation exchange membrane 42 is a membranous member that connects the electrolytic cell 10 and the metal ion supply cell 50 in a manner that allows cations to pass therethrough, based on a voltage applied between the electrolytic cell 10 and the metal ion supply cell 50. More specifically, when a voltage is applied between the electrolytic cell 10 and the metal ion supply cell 50, second membrane-with-diaphragm electrolysis is performed via the cation exchange membrane 42. By the second membrane-with-diaphragm electrolysis using the electrolytic cell-side cathode 12 and the metal ion supply cell-side anode 51, metal ions contained in the third aqueous solution L3 permeate the cation exchange membrane 42 and are supplied to the first aqueous solution L1 (positive direction of the x-axis, indicated by a thick white arrow).

[0073] The cation exchange membrane 42 in this embodiment is not a type of cation exchange membrane through which cations permeate due to osmotic pressure 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 permeate the cation exchange membrane 42 and are supplied to the first aqueous solution L1 by second membrane-with-diaphragm electrolysis using the electrolytic cell-side cathode 12 and the metal ion supply cell-side anode 51, hydroxide ions, which are anions, do not permeate the cation exchange membrane 42.

[0074] The plane of the electrolytic cell-side cathode 12 on the cation exchange membrane 42 side (the yz plane on the negative side of the x-axis) and the plane of the metal ion supply tank-side anode 51 on the cation exchange membrane 42 side (the yz plane on the positive side of the x-axis) are arranged opposite each other. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side cathode 12 and the metal ion supply tank-side anode 51. Because the electric field is generated uniformly, the current between the two electrodes is also distributed uniformly. Therefore, deterioration of the catalytic layer on the surface of each electrode occurs uniformly, and therefore, even when electrolysis is performed repeatedly, uneven deterioration of the catalytic layer on the surface of each electrode due to an uneven electric field can be suppressed. Therefore, a decrease in electrolysis efficiency can be suppressed.

[0075] The electrolytic cell side cathode 12 and the metal ion supply cell side anode 51 are each disposed close to the cation exchange membrane 42. In this specification, "close to" includes both a state in which the electrolytic cell side cathode 12 and the metal ion supply cell side anode 51 are close to the cation exchange membrane 42 with a predetermined gap between them, and a state in which the electrolytic cell side cathode 12 and the metal ion supply cell side anode 51 are in contact with the cation exchange membrane 42.

[0076] [Current control unit 60] The current control unit 60 controls the current used in the membraneless electrolysis, the first membrane electrolysis, and the second membrane electrolysis, which will be described later. Furthermore, based on the voltage value applied in the first membrane electrolysis (corresponding to "membrane electrolysis" in the claims) acquired by the current control unit 60, the delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2.

[0077] The configuration of the current control unit 60 will now be described with reference to Fig. 2. Fig. 2 is a block diagram showing the current control unit 60 according to the first embodiment. As shown in Fig. 2, the current control unit 60 includes a voltage acquisition unit 60a, a calculation unit 60b, and an estimation unit 60c. The voltage acquisition unit 60a may further include a storage unit 60d.

[0078] The voltage acquisition unit 60a is a device, such as a voltmeter, capable of acquiring the voltage value applied between the electrodes. The voltage values ​​acquired by the voltage acquisition unit 60a include, for example, two types: (1) a first voltage value and (2) a second voltage value, which will be described below.

[0079] (1) The first voltage value voltage acquisition unit 60a acquires a first voltage value applied between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. The calculation unit 60b calculates the conductivity of the first aqueous solution L1 based on the first voltage value acquired by the voltage acquisition unit 60a. The estimation unit 60c estimates the chloride ion concentration of the first aqueous solution L1 based on the conductivity of the first aqueous solution L1 calculated by the calculation unit 60b. The current control unit 60 performs current control based on the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c. Details of current control by the current control unit 60 will be described later.

[0080] (2) The second voltage value acquisition unit 60a acquires a second voltage value (referred to as a "voltage value" in the claims) applied between the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21. The second voltage value correlates with the chloride ion concentration of the second aqueous solution L2. An increase in the second voltage value indicates a decrease in the chloride ion concentration contained in the second aqueous solution L2, and a decrease in the second voltage value indicates an increase in the chloride ion concentration contained in the second aqueous solution L2.

[0081] The memory unit 60d stores information relating to the relationship between the second voltage value and the chloride ion concentration of the second aqueous solution L2. The information stored in the memory unit 60d is information previously determined through experiments, etc. Based on the information stored in the memory unit 60d and the acquired second voltage value, the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2, for example, by the methods of Supply Examples 1 to 3 below.

[0082] Supply Example 1: Supplying the high-concentration chloride aqueous solution HC to the second aqueous solution L2 when the chloride ion concentration of the second aqueous solution L2 has decreased to a predetermined concentration When the difference between the reference voltage value and the second voltage value acquired by the voltage acquisition unit 60a becomes equal to or greater than a predetermined amount of change, the delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the acquired second voltage value. Here, the "reference voltage value" refers to the second voltage value that has a correlation with the initial chloride ion concentration of the first aqueous solution L1 stored in the electrolytic bath 10, i.e., the initial chloride ion concentration at the time when the spatial purification device 1 is first used.

[0083] More specifically, the initial chloride ion concentrations of the first aqueous solution L1 and the second aqueous solution L2 are, for example, 50 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 5%). As the space purification device 1 is used (purification operation), chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1, thereby decreasing the chloride ion concentration of the second aqueous solution L2 and increasing the second voltage value. As the purification operation continues, the chloride ion concentration of the second aqueous solution L2 decreases. When the voltage acquisition unit 60a acquires a second voltage value that correlates with, for example, a chloride ion concentration of 10 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 1%), the delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2. In other words, when the second voltage value reaches a predetermined fixed value, the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2. When the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 begins, the second voltage value decreases. When the voltage becomes equal to or less than the reference voltage value acquired by the voltage acquisition unit 60a, the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 is stopped.

[0084] Here, the chloride ion concentration of the first aqueous solution L1 is maintained at a predetermined concentration, as described below. Therefore, the chloride ion concentration of the second aqueous solution L2 can be maintained within a predetermined concentration difference range relative to the chloride ion concentration of the first aqueous solution L1. By maintaining the concentration difference within the predetermined range, water transfer between the first aqueous solution L1 and the second aqueous solution L2 can be suppressed. Note that, within the above-mentioned predetermined concentration difference range, the chloride ion concentration contained in the second aqueous solution L2 may be maintained in a state lower than the chloride ion concentration contained in the first aqueous solution. At this concentration difference, water transfer from the first aqueous solution L1 to the second aqueous solution L2 can be suppressed.

[0085] [Supply Example 2: Maintaining the Chloride Ion Concentration of the Second Aqueous Solution L2 at a Predetermined Concentration] When the second voltage value acquired by the voltage acquisition unit 60a exceeds a reference voltage value, the delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the acquired second voltage value. Since the high-concentration chloride aqueous solution HC is supplied to the first aqueous solution L1 at the time when the second voltage value exceeds the reference voltage value, i.e., when the chloride ion concentration of the first aqueous solution L1 decreases, the chloride ion concentration of the second aqueous solution L2 can be maintained at a predetermined concentration.

[0086] Supply Example 3: Supplying a High-Concentration Chloride Aqueous Solution HC When the Chloride Ion Concentration of the Second Aqueous Solution L2 Decreases by a Predetermined Amount of Change This is similar to Supply Example 1 described above, except that, while in Supply Example 1 the high-concentration chloride aqueous solution HC is supplied to the second aqueous solution L2 when the second voltage value reaches a predetermined fixed value, Supply Example 3 is based on a variable amount of change rather than a fixed value. More specifically, the initial chloride ion concentrations of the first aqueous solution L1 and the second aqueous solution L2 are set to, for example, 50 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 5%). As the purification operation continues, the chloride ion concentration of the second aqueous solution L2 decreases. When the voltage acquisition unit 60a acquires a second voltage value that correlates with, for example, a chloride ion concentration of 10 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 1%), the delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2.

[0087] Here, the chloride ion concentration of the second aqueous solution L2 to which the high-concentration chloride aqueous solution HC has been supplied may be higher or lower than the initial chloride ion concentration. For example, the supply of the high-concentration chloride aqueous solution HC may cause the chloride ion concentration of the second aqueous solution L2 to become 100 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 10%). In this case, the chloride ion concentration of the second aqueous solution L2 may decrease as the purification operation continues, and the next supply of the high-concentration chloride aqueous solution HC may be performed when the chloride ion concentration of the second aqueous solution L2 has decreased to 60 g / L. In this way, the delivery unit 31 may supply the high-concentration chloride aqueous solution HC to the second aqueous solution L2 when the chloride ion concentration of the second aqueous solution L2 has decreased to a predetermined concentration difference value, rather than a predetermined fixed value as in Supply Example 1.

[0088] The voltage acquisition unit 60a may further include a supply amount specifying unit (not shown). When the supply amount specifying unit is included, the high-concentration chloride aqueous solution HC may be supplied to the second aqueous solution L2 by a method different from the supply of the high-concentration chloride aqueous solution HC described in Supply Examples 1 to 3. The supply amount of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 is specified based on the second voltage value acquired by the voltage acquisition unit 60a and the information stored in the memory unit 60d. The delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the supply amount specified by the supply amount specifying unit. By supplying this supply amount of the high-concentration chloride aqueous solution HC to the second aqueous solution L2, the chloride ion concentration of the second aqueous solution L2 is maintained at a predetermined concentration. Therefore, the chloride ion concentration of the second aqueous solution L2 can be maintained within a predetermined concentration difference range with respect to the chloride ion concentration of the first aqueous solution L1.

[0089] The current control unit 60 includes wirings 61, 62, 63, and 64. The wirings 61, 62, 63, and 64 are lines through which current flows. The chloride ion supply tank-side cathode 21 is electrically connected to the current control unit 60 via wiring 61, the electrolytic tank-side anode 11 via wiring 62, the electrolytic tank-side cathode 12 via wiring 63, and the metal ion supply tank-side anode 51 via wiring 64. A portion of each electrode may protrude outside the corresponding tank and be connected to the corresponding wiring.

[0090] Next, the first diaphragm-containing electrolysis unit E1, the second diaphragm-containing electrolysis unit E2 (E2a, E2b), and the diaphragm-less electrolysis unit E3 included in the space purification device 1 according to this embodiment will be described with reference to Figures 3 and 4. The second diaphragm-containing electrolysis unit E2 includes two examples, the second diaphragm-containing electrolysis unit E2a and the second diaphragm-containing electrolysis unit E2b. Therefore, the first example will be described in Figure 3, and the second example will be described in Figure 4.

[0091] <First Example: First Electrolysis Unit with Diaphragm E1, Second Electrolysis Unit with Diaphragm E2a, and Electrolysis Unit without Diaphragm E3> Figure 3 is a partial cross-sectional plan view taken along line III-III in Figure 1, showing a first example of the electrolysis units included in the space purification device 1. In Figure 3, the first electrolysis unit with diaphragm E1 is shown as the area surrounded by a dashed-dotted line rectangle, the second electrolysis unit with diaphragm E2a is shown as the area surrounded by a dashed-dotted line rectangle, and the Electrolysis Unit without Diaphragm E3 is shown as the area surrounded by a broken-line rectangle.

[0092] The first membrane-containing electrolysis unit E1 is provided across the electrolytic cell 10 and the chloride ion supply cell 20. The first membrane-containing electrolysis unit E1 includes an electrolytic cell-side anode 11, a chloride ion supply cell-side cathode 21, and an anion exchange membrane 41. The first membrane-containing electrolysis unit E1 performs first membrane-containing electrolysis via the anion exchange membrane 41 by passing a first current between the pair of the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21.

[0093] The second membrane-based electrolysis unit E2a is provided across the chloride ion supply tank 20 and the metal ion supply tank 50. The second membrane-based electrolysis unit E2a includes a chloride ion supply tank-side cathode 21, a metal ion supply tank-side anode 51, an anion exchange membrane 41, and a cation exchange membrane 42. The second membrane-based electrolysis unit E2a performs second membrane-based electrolysis via the anion exchange membrane 41 and the cation exchange membrane 42 by passing a second current between the pair of the chloride ion supply tank-side cathode 21 and the metal ion supply tank-side anode 51.

[0094] The diaphragm-free electrolysis unit E3 is provided in the electrolytic cell 10. The diaphragm-free electrolysis unit E3 includes an electrolytic cell-side anode 11 and an electrolytic cell-side cathode 12. The diaphragm-free electrolysis unit E3 generates hypochlorous acid by electrolyzing the third aqueous solution without a diaphragm by passing a third current between the pair of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12.

[0095] As described above, in the first example, the chloride ion supply tank side cathode 21 is used in the first membrane electrolysis and the second membrane electrolysis, and the electrolytic tank side anode 11 is used in the first membrane electrolysis and the membraneless electrolysis.

[0096] <Second Example: First Diaphragm-Included Electrolysis Unit E1, Second Diaphragm-Included Electrolysis Unit E2b, and Diaphragm-Free Electrolysis Unit E3> Figure 4 is a partial cross-sectional plan view taken along line III-III in Figure 1, illustrating a second example of the electrolysis units included in the space purification device 1. In Figure 4, the first diaphragm-included electrolysis unit E1 is indicated by a dashed-dotted rectangle, the second diaphragm-included electrolysis unit E2b is indicated by a dashed-dotted rectangle, and the diaphragm-free electrolysis unit E3 is indicated by a broken-dashed rectangle. The configuration of the space purification device 1 in the second example, the first diaphragm-included electrolysis unit E1, and the diaphragm-free electrolysis unit E3 are the same as those in the first example, so their description will be omitted in this example, and only the second diaphragm-included electrolysis unit E2b will be described.

[0097] The second membrane-with-diaphragm electrolysis unit E2b is provided across the electrolytic cell 10 and the metal ion supply cell 50. The second membrane-with-diaphragm electrolysis unit E2b includes an electrolytic cell-side cathode 12, a metal ion supply cell-side anode 51, and a cation exchange membrane 42. The second membrane-with-diaphragm electrolysis unit E2b performs second membrane-with-diaphragm electrolysis via the cation exchange membrane 42 by passing a second current between the pair of the electrolytic cell-side cathode 12 and the metal ion supply cell-side anode 51.

[0098] As described above, in the second example, the electrolytic cell side anode 11 is used for the first electrolysis with a diaphragm and the electrolysis without a diaphragm, and the electrolytic cell side cathode 12 is used for the second electrolysis with a diaphragm and the electrolysis without a diaphragm.

[0099] The current control unit 60 (see FIGS. 1 and 2 ) controls the first current used in the first electrolysis with a diaphragm, the second current used in the second electrolysis with a diaphragm, and the third current used in the electrolysis without a diaphragm. In other words, the current control unit 60 controls the first current passed through the first electrolysis unit with a diaphragm E1, the second current passed through the second electrolysis unit with a diaphragm E2 (E2a, E2b), and the third current passed through the electrolysis unit without a diaphragm E3, thereby controlling the chemical reaction occurring in the first electrolysis unit with a diaphragm E1, the chemical reaction occurring in the second electrolysis unit with a diaphragm E2, and the chemical reaction occurring in the electrolysis unit without a diaphragm E3.

[0100] 5 to 7, the chemical reactions occurring in the first electrolysis unit with diaphragm E1, the second electrolysis unit with diaphragm E2, and the non-diaphragm electrolysis unit E3 will be described in detail below. The following describes a case where the first aqueous solution L1 is a sodium chloride aqueous solution, the second aqueous solution L2 is a magnesium chloride aqueous solution, and the third aqueous solution L3 is a disodium hydrogen phosphate aqueous solution.

[0101] [First diaphragm electrolysis unit E1] In the first diaphragm electrolysis unit E1, reactions occur in both the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21 via the anion exchange membrane 41. That is, in the first diaphragm electrolysis unit E1, reactions occur in both the first aqueous solution L1 stored in the electrolytic cell 10 and the second aqueous solution L2 stored in the chloride ion supply cell 20.

[0102] FIG. 5 shows a list of chemical reactions occurring in the first aqueous solution L1 stored in the electrolytic cell 10 of the first membrane-containing electrolysis unit E1 and chemical reactions occurring in the second aqueous solution L2 stored in the chloride ion supply tank 20.

[0103] When a predetermined voltage is applied to the first membrane-containing electrolysis unit E1, a first current flows, electrons move, and the chemical reactions shown in Fig. 5 occur. Note that the chemical reactions shown in Figs. 5(a) to 5(f) that occur in the first aqueous solution L1 stored in the electrolytic cell 10 also occur in the membrane-less electrolysis unit E3.

[0104] First, with reference to FIGS. 5(a) to 5(f), the reactions occurring in the first aqueous solution L1 stored in the electrolytic cell 10 will be described.

[0105] <Electrolytic cell 10 (first aqueous solution L1)> FIG. 5( a): Anion exchange membrane 41. When a voltage is applied to the first membrane-type electrolysis unit E1 and a first current flows, the first current flows between the electrolytic cell-side anode 11 and the chloride ion supply tank-side cathode 21, and the water (H ２ O) to electrons (e － ) contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 moves. －) permeates the anion exchange membrane 41 and is supplied to the first aqueous solution L1 stored in the electrolytic cell 10. The chloride ions (Cl － ) is used in the following reaction formula (b) in FIG. 5. In other words, in the first aqueous solution L1, the electrons (e － ) is converted into chloride ions (Cl － ) can be said to be

[0106] Subsequently, as shown in reaction formula (b) and reaction formula (c) of FIG. 5, two types of reactions occur at the electrolytic cell-side anode 11, involving chlorine (liquid) and oxygen (gas).

[0107] Reaction formula (b) in FIG. 5: Electrolytic cell-side anode 11 (chlorine generation reaction) Sodium chloride (NaCl) contained in the sodium chloride aqueous solution, which is the first aqueous solution L1, generates sodium ions (Na ＋ ) and chloride ions (Cl － 5A, chloride ions (Cl ) are ionized from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41. － ) is supplied to the electrolytic cell side anode 11. － ) and chloride ions (Cl ) supplied from the first aqueous solution L1 － ) is an electron (e － ) and loses chlorine (Cl ２ (liquid, aq.)) is generated.

[0108] Reaction formula (c) in FIG. 5: Electrolytic cell-side anode 11 (oxygen generation reaction) At the electrolytic cell-side anode 11, the water (H ２ O) to electrons (e － ) is taken away, and oxygen (O ２ ) and hydrogen ions (H ＋ ) occurs.

[0109] Reaction formula (d) in FIG. 5: In the first aqueous solution L1 (hypochlorous acid generation reaction) In the first aqueous solution L1 stored in the electrolytic cell 10, chlorine (Cl ) generated by reaction formula (b) in FIG. ２ ) is the water (H ２O), hydrolysis occurs, generating hydrochloric acid (HCl) and hypochlorous acid (HClO). Hydrochloric acid (HCl) ionizes in an aqueous solution, generating hydrogen ions (H ＋ ) and chloride ions (Cl － ) exists.

[0110] 5: Hypochlorous acid generating reaction (equilibrium reaction formula) The equilibrium reaction formula of the hypochlorous acid generating reaction is shown. － Depending on the increase or decrease of Cl contained in the first aqueous solution L1 stored in the electrolytic cell 10, the equilibrium state may shift to the right or to the left. － The current control described below is performed so that the apparent increase or decrease does not occur.

[0111] Formula (f) in Figure 5: Chloride ion change formula during electrolysis Formula (f) in Figure 5 is a single formula that combines reaction formulas (b) and (d) in Figure 5. The chlorine (Cl) produced by reaction formula (b) in Figure 5 ２ ) is converted into hydrochloric acid (HCl) and hypochlorous acid (HClO) according to reaction formula (d) in FIG. 5.

[0112] Next, with reference to FIGS. 5(g) to 5(i), the reaction occurring in the second aqueous solution L2 stored in the chloride ion supply tank 20 will be described.

[0113] <Chloride ion supply tank 20 (second aqueous solution L2)> FIG. 5( g): When a voltage is applied to the first diaphragm electrolysis unit E1 and a first current flows, chloride ions (Cl ) contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 are converted into chloride ions (Cl ). － ) permeates the anion exchange membrane 41 and is supplied to the first aqueous solution L1 stored in the electrolytic cell 10. The chloride ions (Cl － ) is used in the reaction formula (b) of FIG. 5 described above. In addition, when a first current flows between the electrolytic cell-side anode 11 and the chloride ion supplying cell-side cathode 21, the water (H ２ O) is electron (e － In other words, in the second aqueous solution L2, chloride ions (Cl ) are received before the first current flows (before the change).－ ) after the first current flows (after the change), electrons (e － ) The water (H ２ O) is electron (e － The reaction occurring when the cation is added is shown in reaction formula (h) in FIG. 5.

[0114] Reaction formula (h) in FIG. 5: Chloride ion supply tank side cathode 21 (hydrogen generation reaction) At the chloride ion supply tank side cathode 21, the water (H ２ O) is electron (e － ) and hydrogen (H ２ ) and hydroxide ions (OH － The hydrogen is evaporated as a gas from the first outlet 23, and hydroxide ions are used in the following reaction formula (i) in FIG. 5.

[0115] Reaction formula (i) in FIG. 5: In the second aqueous solution L2 (magnesium hydroxide precipitation reaction) The magnesium ions (Mg ２＋ ) and hydroxide ions (OH － ) reacts with magnesium hydroxide (Mg(OH) ２ ) A precipitate is formed.

[0116] Here, magnesium hydroxide (Mg(OH) ２ ) is solubility product Ksp = 1.2 × 10 －１１ (mol / L) ３ For example, magnesium hydroxide is soluble in a weakly alkaline aqueous solution with a pH of 10, at only 1.2 × 10 －３ In the second aqueous solution L2 of the chloride ion supply tank 20, hydroxide ions (OH － ) is used to generate magnesium hydroxide precipitate, thereby generating hydroxide ions (OH － ) and the increase in the pH of the second aqueous solution L2 can be suppressed.

[0117] Furthermore, when a magnesium chloride aqueous solution is used as the second aqueous solution L2, the pH of the magnesium hydroxide saturated aqueous solution produced after the first diaphragm electrolysis, in which magnesium hydroxide is saturated, is pH 10.36 as determined from the solubility product. Therefore, even after the first diaphragm electrolysis is performed over a long period of time, the pH of the second aqueous solution L2 can be maintained in a weakly alkaline state of up to 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 prevent the second aqueous solution L2 from becoming strongly alkaline, with a pH of 11 or more. Therefore, it is possible to provide a space purification device 1 that is safer by preventing the second aqueous solution L2 stored in the chloride ion supply tank 20 from becoming strongly alkaline after electrolysis.

[0118] Furthermore, for example, the space purification device 1 according to this embodiment may be installed by a contractor. After use, the space purification device 1 may be overturned or dropped when the contractor removes the installed space purification device or during transportation after removal. 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 space purification device 1 due to overturning or dropping, safety can be improved compared to space purification devices using a sodium chloride aqueous solution.

[0119] Next, the chemical reactions occurring in the second diaphragm electrolysis section will be described with reference to Figures 6 and 7. Regarding the second diaphragm electrolysis section, both the second diaphragm electrolysis section E2a (configuration see Figure 3) as a first example and the second diaphragm electrolysis section E2b (configuration see Figure 4) as a second example will be described with reference to Figure 6. First, the first example of the second diaphragm electrolysis section E2a will be described.

[0120] [Second diaphragm electrolysis unit E2a] In the second diaphragm electrolysis unit E2a, reactions occur in both the chloride ion supply tank side cathode 21 and the metal ion supply tank side anode 51 via the anion exchange membrane 41 and the cation exchange membrane 42. That is, in the second diaphragm electrolysis unit E2a, reactions occur in both the second aqueous solution L2 stored in the chloride ion supply tank 20 and the third aqueous solution L3 stored in the metal ion supply tank 50. Through the reactions in the second diaphragm electrolysis unit E2a, chloride ions are supplied from the second aqueous solution L2 to the first aqueous solution L1 stored in the electrolytic tank 10, and metal ions are supplied from the third aqueous solution L3 to the first aqueous solution L1 stored in the electrolytic tank 10. For example, when 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.

[0121] Chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 stored in the electrolytic cell 10 by the reaction in the second diaphragm electrolysis unit E2a cause the hypochlorous acid generation reaction described using reaction formula (d) in Fig. 5 in the first aqueous solution L1. In other words, when the second diaphragm electrolysis unit E2a is used, chloride ions are supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 10 by both the first diaphragm electrolysis unit E1 and the second diaphragm electrolysis unit E2a. The second diaphragm electrolysis unit E2b, which will be described later, does not supply chloride ions from the second aqueous solution L2 to the first aqueous solution L1. Therefore, for example, when the amount of the first current is a predetermined value, when the second diaphragm electrolysis unit E2a is used, more chloride ions can be supplied to the electrolytic cell 10 than when the second diaphragm electrolysis unit E2b is used.

[0122] FIG. 6 shows a list of chemical reactions occurring in the second aqueous solution L2 stored in the chloride ion supply tank 20 of the second membrane-containing electrolysis unit E2a and chemical reactions occurring in the third aqueous solution L3 stored in the metal ion supply tank 50.

[0123] When a predetermined voltage is applied to the second membrane-containing electrolysis unit E2a, a second current flows, electrons move, and the chemical reaction shown in Fig. 6 occurs. First, with reference to Figs. 6(a) to 6(c), the chemical reaction occurring in the second aqueous solution L2 stored in the chloride ion supply tank 20 will be described. Note that the chemical reaction occurring in the second aqueous solution L2 stored in the chloride ion supply tank 20 shown in Figs. 6(a) to 6(c) is substantially the same as the chemical reaction described using Figs. 5(g) to 5(i).

[0124] <Chloride ion supply tank 20 (second aqueous solution L2)> FIG. 6( a): When a voltage is applied to the second diaphragm electrolysis unit E2 and a second current flows, chloride ions (Cl ) contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 are converted into chloride ions (Cl ). － ) permeates the anion exchange membrane 41 and is supplied to the first aqueous solution L1 stored in the electrolytic cell 10. The chloride ions (Cl － ) is used in the reaction formula (b) of FIG. 5 described above. In addition, when a second current flows between the chloride ion supply tank side cathode 21 and the metal ion supply tank side anode 51, the water (H ２ O) is electron (e － In other words, in the second aqueous solution L2, chloride ions (Cl ) are received before the first current flows (before the change). － ) after the first current flows (after the change), electrons (e － ) The water (H ２ O) is electron (e － The reaction that occurs when the cation exchange reaction (C) is received is shown in reaction formula (b) in FIG. 6 below.

[0125] Reaction formula (b) of FIG. 6: Chloride ion supply tank side cathode 21 (hydrogen generation reaction) At the chloride ion supply tank side cathode 21, the water (H ２ O) is electron (e － ) and hydrogen (H ２ ) and hydroxide ions (OH － The hydrogen is evaporated as a gas from the first outlet 23, and hydroxide ions are used in the following reaction formula (c) in FIG. 6.

[0126] Reaction formula (c) in FIG. 6: In the second aqueous solution L2 (magnesium hydroxide precipitation reaction) The magnesium ions (Mg ２＋ ) and hydroxide ions (OH － ) reacts with magnesium hydroxide (Mg(OH) ２ ) A precipitate is formed.

[0127] Next, with reference to FIGS. 6(d) and 6(e), the reaction occurring in the third aqueous solution L3 stored in the metal ion supply tank 50 will be described.

[0128] <Metal ion supply tank 50 (third aqueous solution L3)> Reaction formula (d) in FIG. 6: Metal ion supply tank side anode 51 (oxygen generation reaction) At the metal ion supply tank side anode 51, water (H ２ O) to electrons (e － ) is taken away, and oxygen (O ２ ) and hydrogen ions (H ＋ The oxygen is vaporized as a gas from the second outlet 53.

[0129] When a voltage is applied to the second membrane electrolysis unit E2a and a second current flows, the sodium ions (Na ＋ ) permeates the cation exchange membrane 42 and is supplied to the first aqueous solution L1. In addition, when a second current flows between the chloride ion supply tank side cathode 21 and the metal ion supply tank side anode 51, electrons (e － ) moves from the metal ion supply tank side anode 51 to the second aqueous solution L2 through the chloride ion supply tank side cathode 21. In other words, the sodium ions (Na ＋ ) and electrons (e － ) is lost from the third aqueous solution L3 after the second current flows (after the change). ２ O) is electron (e －The reaction that occurs when the hydroxyl group 12 receives the hydroxyl group 13 is as explained using reaction formula (b) in FIG.

[0130] [Second membrane electrolysis unit E2b] Next, a second example of the second membrane electrolysis unit E2b will be described with reference to Fig. 7. Fig. 7 shows a list of chemical reactions occurring in the third aqueous solution L3 stored in the metal ion supply tank 50 of the second membrane electrolysis unit E2b and chemical reactions occurring in the first aqueous solution L1 stored in the electrolysis tank 10.

[0131] In the second membrane-equipped electrolysis unit E2b, reactions occur in both the metal ion supply tank-side anode 51 and the electrolytic tank-side cathode 12 via the cation exchange membrane 42. That is, in the second membrane-equipped electrolysis unit E2b, reactions occur in both the third aqueous solution L3 stored in the metal ion supply tank 50 and the first aqueous solution L1 stored in the electrolytic tank 10. First, with reference to FIGS. 7( a) and 7(b), the reactions occurring in the third aqueous solution L3 stored in the metal ion supply tank 50 will be described. The reactions occurring in the third aqueous solution L3 shown in FIGS. 7( a) and 7(b) are substantially the same as the chemical reactions described using FIGS. 6(d) and 6(e).

[0132] <Metal ion supply tank 50 (third aqueous solution L3)> Reaction formula (a) of FIG. 7: metal ion supply tank side anode 51 (oxygen generation reaction) In the metal ion supply tank side anode 51, water (H ２ O) to electrons (e － ) is taken away, and oxygen (O ２ ) and hydrogen ions (H ＋ The generated oxygen volatilizes as a gas from the second outlet 53.

[0133] 7(b): When a voltage is applied to the second membrane electrolysis unit E2b of the cation exchange membrane 42 and a second current flows, sodium ions (Na ＋ ) passes through the cation exchange membrane 42 and is supplied to the first aqueous solution L1. In addition, when a second current flows between the metal ion supply tank side anode 51 and the electrolytic tank side cathode 12, the electrons (e －) moves from the metal ion supply tank side anode 51 to the first aqueous solution L1 through the electrolytic tank side cathode 12. In other words, the sodium ions (Na ＋ ) and electrons (e － ) is lost from the third aqueous solution L3 after the second current flows (after the change). ２ O) is electron (e － The reaction that occurs when the cations of ...

[0134] Next, with reference to FIGS. 7(c) and 7(d), the reactions occurring in the first aqueous solution L1 stored in the electrolytic cell 10 will be described.

[0135] <Electrolytic cell 10 (first aqueous solution L1)> - Cation exchange membrane 42 in FIG. 7 (c) As described above in FIG. 7 (b), when a voltage is applied to the second membrane electrolysis unit E2b and the second current flows, sodium ions (Na ＋ ) and electrons (e － ) is supplied to the first aqueous solution L1. In other words, before the second current flows (before the change), the first aqueous solution L1 does not contain sodium ions and electrons derived 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.

[0136] Reaction formula (d) in FIG. 7: Electrolytic cell-side cathode 12 (hydrogen generation reaction) At the electrolytic cell-side cathode 12, the water (H ２ O) is electron (e － ) and hydrogen (H ２ ) and hydroxide ions (OH － ) occurs.

[0137] Next, the chemical reaction occurring in the diaphragm-free electrolysis unit E3 will be described with reference to Fig. 8. In the diaphragm-free electrolysis unit E3, a reaction occurs in the first aqueous solution L1 stored in the electrolytic cell 10, without the intervention of an ion exchange membrane, at both the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. That is, in the diaphragm-free electrolysis unit E3, a reaction occurs only in the first aqueous solution L1 stored in the electrolytic cell 10.

[0138] [Diaphragm-free electrolysis unit E3 (electrolytic cell 10)] Fig. 8 is a list of reaction formulas that occur in the first aqueous solution L1 stored in the electrolytic cell 10 of the diaphragm-free electrolysis unit E3. When a predetermined voltage is applied to the diaphragm-free electrolysis unit E3, a third current flows, electrons are transferred, and chemical reactions shown in reaction formulas (a) to (g) in Fig. 8 occur.

[0139] Before describing the membraneless electrolysis section E3, the changes will be described.

[0140] First, chloride ions from the second aqueous solution L2 and sodium ions and electrons from the third aqueous solution L3 are supplied to the first aqueous solution L1 stored in the electrolytic cell 10.

[0141] 8(a): Anion exchange membrane 41 As described above, when a voltage is applied to the first membrane electrolysis section E1 and the second membrane electrolysis section E2a and the first current and the second current flow, the first aqueous solution L1 stored in the electrolytic cell 10 generates electrons (e － ) is lost. － In the first aqueous solution L1, which has lost its chloride ions (Cl), a force that maintains electrical neutrality acts, and negatively charged chloride ions (Cl － ) is supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic tank 10 through the anion exchange membrane 41. In the first aqueous solution L1, the electrons (e － ) changes to chloride ions (Cl － ) can be said to be

[0142] Subsequently, as shown in reaction formula (b) of FIG. 8 and reaction formula (c) of FIG. 4, two types of reactions occur at the electrolytic cell-side anode 11, involving chlorine (liquid) and oxygen (gas).

[0143] Reaction formula (b) in FIG. 8: Electrolytic cell-side anode 11 (chlorine generation reaction) Sodium chloride (NaCl) contained in the sodium chloride aqueous solution, which is the first aqueous solution L1, generates sodium ions (Na ＋ ) and chloride ions (Cl － 8A, chloride ions (Cl ) are ionized from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41. － ) is supplied to the electrolytic cell side anode 11. － ) and chloride ions (Cl ) supplied from the first aqueous solution L1 － ) is an electron (e － ) and loses chlorine (Cl ２ (liquid, aq.)) is generated.

[0144] Reaction formula (c) in FIG. 8: Electrolytic cell-side anode 11 (oxygen generation reaction) At the electrolytic cell-side anode 11, the water (H ２ O) to electrons (e － ) is taken away, and oxygen (O ２ ) and hydrogen ions (H ＋ ) occurs.

[0145] When a voltage is applied to the second membrane electrolysis unit E2a or the second membrane electrolysis unit E2b and a second current flows, sodium ions (Na ＋ ) and electrons (e － ) is supplied to the first aqueous solution L1. In other words, before the second current flows (before the change), the first aqueous solution L1 does not contain sodium ions and electrons derived 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.

[0146] Reaction formula (e) in FIG. 8: Electrolytic cell-side cathode 12 (hydrogen generation reaction) At the electrolytic cell-side cathode 12, the water (H ２ O) is electron (e － ) and hydrogen (H ２ ) and hydroxide ions (OH － ) occurs.

[0147] Reaction formula (f) in FIG. 8: In the first aqueous solution L1 (hypochlorous acid generation reaction) In the first aqueous solution L1 stored in the electrolytic cell 10, chlorine (Cl ) generated by reaction formula (b) in FIG. ２ ) is the water (H ２ O), hydrolysis occurs, generating hydrochloric acid (HCl) and hypochlorous acid (HClO). Hydrochloric acid (HCl) ionizes in an aqueous solution, generating hydrogen ions (H ＋ ) and chloride ions (Cl － ) are present in the first aqueous solution L1. In addition, hydrogen ions generated by reaction formula (c) in FIG. 8 are present in the first aqueous solution L1. ＋ ) is the hydroxide ion (OH) generated in reaction formula (e) of FIG. － ) to form water. That is, the pH of the first aqueous solution L1 may decrease with the generation of hydrogen ions in the first aqueous solution L1, but the hydrogen ions (H ＋ ) and hydroxide ions (OH － ) reacts with the water, thereby suppressing a decrease in pH of the first aqueous solution L1 due to an increase in hydrogen ions.

[0148] 8: Hypochlorous acid generating reaction (equilibrium reaction formula) The equilibrium reaction formula of the hypochlorous acid generating reaction is shown below. － Depending on the increase or decrease of Cl in the electrolytic cell 10, the equilibrium state may shift to the right or to the left. － The current control described below is performed so that the apparent increase or decrease does not occur.

[0149] Equation (h) of Figure 8: Equation of chloride ion change during electrolysis Equation (h) of Figure 8 is a single equation that combines reaction equations (b) and (f) of Figure 8. The chlorine (Cl) produced by reaction equation (b) of Figure 8 ２ ) is converted into hydrochloric acid (HCl) and hypochlorous acid (HClO) according to reaction formula (f) in FIG. 8.

[0150] The current control unit 60 controls the above-mentioned chemical reaction by controlling electrolysis. Here, bubbling of the first aqueous solution L1 during the purification operation of the space purification device 1 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 10 located in the electrolytic cell-side inner space 15, and only the water evaporates from the droplets, causing the sodium chloride remaining on the inner wall surface of the electrolytic cell 10 to crystallize into a white color, which is called salt splashing. The salt splashing also includes the sodium chloride aqueous solution flying into the external space R as droplets together with the mixed air M discharged from the discharge port 17. Therefore, in the electrolytic cell 10, (1) a reduction in chloride ions due to diaphragm-less electrolysis in the diaphragm-less electrolysis unit E3, and (2) a reduction in chloride ions (Cl) due to salt splashing. － ) may decrease.

[0151] The current control performed in the first and second examples, which have different configurations of the second membrane electrolysis section, will be described below.

[0152] <First Example: Case of First Electrolysis Unit with Diaphragm E1, Second Electrolysis Unit with Diaphragm E2a, and Electrolysis Unit without Diaphragm E3> The current control unit 60 (1) controls the first current so as to replenish chloride ions contained in the first aqueous solution L1 that have been reduced by diaphragm-less electrolysis in the diaphragm-less electrolysis unit E3, thereby causing chloride ions contained in the second aqueous solution L2 to permeate through the anion exchange membrane 41 and be supplied to the first aqueous solution L1. Furthermore, when the first aqueous solution L1 is a sodium chloride aqueous solution, the current control unit 60 (2) controls the second current of the second electrolysis unit with diaphragm E2a so as to replenish chloride ions and sodium ions contained in the first aqueous solution L1 that have been reduced by salt splashing, thereby causing chloride ions contained in the second aqueous solution L2 to permeate through the anion exchange membrane 41 and be supplied to the first aqueous solution L1, and sodium ions contained in the third aqueous solution L3 to be supplied to the first aqueous solution L1.

[0153] The current control unit 60 supplies the first current, the second current, and the third current at a predetermined ratio so as to replenish the chloride ions that have decreased in the first aqueous solution L1 while maintaining the hypochlorous acid concentration in the third aqueous solution at a predetermined concentration.

[0154] <Second Example: In the Case of the First Electrolysis Unit with Diaphragm E1, the Second Electrolysis Unit with Diaphragm E2b, and the Electrolysis Unit without Diaphragm E3> The current control unit 60 (1) controls the first current so as to replenish chloride ions contained in the first aqueous solution L1 that have been reduced by diaphragm-less electrolysis in the diaphragm-less electrolysis unit E3, thereby causing chloride ions contained in the second aqueous solution L2 to pass through the anion exchange membrane 41 and be supplied to the first aqueous solution L1. Furthermore, when the first aqueous solution L1 is a sodium chloride aqueous solution, the current control unit 60 (2) controls the first current and the second current of the second electrolysis unit with diaphragm E2b so as to replenish chloride ions and sodium ions contained in the first aqueous solution L1 that have been reduced by salt splashing, thereby supplying 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.

[0155] The current control unit 60 supplies the first current, the second current, and the third current at a predetermined ratio so as to replenish the chloride ions that have decreased in the first aqueous solution L1 and maintain the hypochlorous acid concentration in the first aqueous solution L1 at a predetermined concentration.

[0156] Three examples of current control by the current control unit 60 will be described below. Similar control is performed in both the first and second examples, which have different configurations for the second diaphragm electrolysis. Before the current control unit 60 changes the current proportions of the first current (first diaphragm electrolysis), the second current (second diaphragm electrolysis), and the third current (diaphragmless electrolysis), the current proportions of the third current are greatest, followed by the current proportion of the first current, and then the current proportion of the second current is smallest.

[0157] <First Example: In the Case of the First Electrolysis Unit with Diaphragm E1, the Second Electrolysis Unit with Diaphragm E2a, and the Electrolysis Unit without Diaphragm E3> [1. When the First Current, the Second Current, and the Third Current are Simultaneously Passed] When the first current, the second current, and the third current are simultaneously passed, the current control unit 60 performs control to change or not change the current ratios in the following (1) to (3). (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimating unit 60c is lower than a predetermined concentration: The current ratios of the first current, the second current, and the third current are changed so as to increase the amount of chloride ions that permeate from the second aqueous solution L2 through the anion exchange membrane 41 and are supplied to the first aqueous solution L1. More specifically, the current ratio of the first current is increased or not changed, the current ratio of the second current is increased, and the current ratio of the third current is not increased or not changed. In the first example, by passing the first current, chloride ions are supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic tank 10. Furthermore, by passing the second current, chloride ions are also supplied from the second aqueous solution L2 stored in the chloride ion supply tank 20 to the first aqueous solution L1 stored in the electrolytic tank 10. On the other hand, the second current flowing in the second diaphragm electrolysis unit E2b described below does not supply chloride ions from the second aqueous solution L2 to the first aqueous solution L1. Therefore, when the second diaphragm electrolysis unit E2a is used, more chloride ions can be supplied to the electrolytic tank 10 than when the second diaphragm electrolysis unit E2b is used.

[0158] Furthermore, when it is desired to supply chloride ions from the third aqueous solution to the first aqueous solution so as to increase the supply amount of chloride ions by a predetermined amount, in the case where the second membrane electrolysis unit E2a is used, a predetermined amount of chloride ions can be supplied from the third aqueous solution to the first aqueous solution by increasing only the second current or by increasing both the first current and the second current.

[0159] On the other hand, when the second membrane electrolysis unit E2b described below is used, if it is desired to supply chloride ions from the third aqueous solution to the first aqueous solution so as to increase the supply amount of chloride ions by a predetermined amount, it is necessary to supply a predetermined amount of chloride ions from the third aqueous solution to the first aqueous solution by increasing the first current amount of the first membrane electrolysis.

[0160] Here, if the first current amount of the first diaphragm electrolysis and the second current amount of the second diaphragm electrolysis are increased so as to increase the amount of chloride ions supplied from the second aqueous solution L2 to the first aqueous solution L1 through the anion exchange membrane 41, hydrogen ions in the first aqueous solution L1 increase due to the oxygen generation reaction at the electrolytic cell anode 11 (see FIG. 8( c) ). This increase in hydrogen ions may decrease the pH of the first aqueous solution L1, thereby suppressing the generation of hypochlorous acid. Therefore, in the first example, by increasing both the first current and the second current, a predetermined amount of chloride ions can be supplied from the first aqueous solution to the third aqueous solution. Therefore, compared to the case where the second diaphragm electrolysis unit E2b in the second example is used, the increase in hydrogen ions in the first aqueous solution L1 that occurs with an increase in the current ratio of the first current (increase in the current amount) can be suppressed, and the decrease in pH in the first aqueous solution L1 can be suppressed. Note that the second diaphragm electrolysis unit E2b performs a separate control to suppress the decrease in pH in the first aqueous solution L1. This control will be described later. (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is higher than a predetermined concentration: The first current, the second current, and the third current are changed so as to reduce the amount of chloride ions that permeate from the second aqueous solution L2 through the anion exchange membrane 41 and are supplied to the first aqueous solution L1. More specifically, the current proportion of the first current is decreased or not changed, the current proportion of the second current is decreased, and the current proportion of the third current is not changed. (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is a predetermined concentration: The current proportions of the first current, the second current, and the third current are not changed.

[0161] [2. Controlling the First and Second Currents Simultaneously While Passing the Third Current at a Predetermined Value] When the current control unit 60 controls the first and second currents while passing the third current at a predetermined value, the current control unit 60 performs the following controls (1) to (3). (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is lower than a predetermined concentration: The first and second currents are passed so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. For example, the first and third currents are passed at predetermined values, and the second current is increased so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. Furthermore, the second current may be stopped if the chloride ion concentration of the first aqueous solution L1 is equal to or higher than the predetermined concentration. If the second current has been stopped, the second current is released from the stop state and the second current is passed again so as to increase the amount of chloride ions that are supplied to the first aqueous solution L1. (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is higher than a predetermined concentration: the first current and the second current are stopped so as to stop the supply of chloride ions from the third aqueous solution L3 to the first aqueous solution L1. (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is a predetermined concentration: the current ratio of the first current, the second current, and the third current is not changed.

[0162] [3. When the First Current and the Second Current, or the Third Current are Passed] When the current control unit 60 passes the first current, the second current, or the third current, the current control unit 60 performs the following controls (1) to (3). (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is lower than a predetermined concentration: The third current is stopped and the first current and the second current are passed simultaneously so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is higher than a predetermined concentration: The first current and the second current are stopped and the third current is passed simultaneously so as to stop the supply of chloride ions from the second aqueous solution L2 to the first aqueous solution L1. (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is a predetermined concentration: The current ratio of the first current, the second current, and the third current is not changed.

[0163] As described above, the current control unit 60 controls the first current, the second current, and the third current, so that the necessary amount of chloride ions can be supplied to the first aqueous solution L1 stored in the electrolytic cell 10, and the hypochlorous acid concentration in the first aqueous solution L1 can be maintained at a predetermined concentration.

[0164] <Second Example: In the Case of the First Electrolysis Unit E1 with Diaphragm, the Second Electrolysis Unit E2b with Diaphragm, and the Electrolysis Unit E3 without Diaphragm> [1. When the First Current, the Second Current, and the Third Current are Simultaneously Passed] When the first current, the second current, and the third current are simultaneously passed, the current control unit 60 performs control to change or not change the current ratios in the following (1) to (3). (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimating unit 60c is lower than a predetermined concentration: The current ratios of the first current, the second current, and the third current are changed so as to increase the amount of chloride ions that permeate from the second aqueous solution L2 through the anion exchange membrane 41 and are supplied to the first aqueous solution L1. More specifically, the current ratio of the first current is increased, and the current ratio of the second current is increased so as to correspond to the increase in the current ratio of the first current, and the current ratio of the third current is not increased or changed.

[0165] Here, when the first current amount of the first diaphragm electrolysis is increased so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1, hydrogen ions in the first aqueous solution L1 increase due to the oxygen generation reaction (see FIG. 8( c)) at the electrolytic cell-side anode 11. When the hydrogen ions increase, the pH of the first aqueous solution L1 decreases, and there is a risk that the generation of hypochlorous acid will be suppressed. Therefore, in the second example, by increasing the current rate of the second current so as to correspond to the increase in the current rate of the first current, the amount of current flowing to the electrolytic cell-side cathode 12 also increases, and hydroxide ions (OH － ) is promoted (see FIG. 8(e)).

[0166] Therefore, the hydrogen ions increased by increasing the current rate of the first current react with hydroxide ions generated by increasing the current rate of the second current to form water. Therefore, by increasing the current rate of the second current in proportion to the increase in the current rate of the first current, a decrease in the pH of the first aqueous solution L1 due to an increase in hydrogen ions can be suppressed. (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is higher than a predetermined concentration: The first current, the second current, and the third current are changed so as to reduce the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. More specifically, the current rate of the first current is decreased, the current rate of the second current is decreased, and the current rate of the third current is increased or not changed. (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is a predetermined concentration: The current rates of the first current, the second current, and the third current are not changed.

[0167] [2. Controlling the First and Second Currents Simultaneously While Passing the Third Current at a Predetermined Value] When the current control unit 60 controls the first and second currents while passing the third current at a predetermined value, the current control unit 60 performs the following controls (1) to (3). (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is lower than a predetermined concentration: The first and second currents are passed so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. For example, the first and third currents are passed at predetermined values, and the second current is increased so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. Furthermore, the second current may be stopped if the chloride ion concentration of the first aqueous solution L1 is equal to or higher than the predetermined concentration. If the second current has been stopped, the second current is released from the stop state and the second current is passed again so as to increase the amount of chloride ions that are supplied to the first aqueous solution L1. (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is higher than a predetermined concentration: the first current and the second current are stopped so as to stop the supply of chloride ions from the third aqueous solution L3 to the first aqueous solution L1. (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is a predetermined concentration: the current ratio of the first current, the second current, and the third current is not changed.

[0168] [3. When the First Current and the Second Current, or the Third Current are Passed] When the current control unit 60 passes the first current, the second current, or the third current, the current control unit 60 performs the following controls (1) to (3). (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is lower than a predetermined concentration: The third current is stopped and the first current and the second current are passed simultaneously so as to increase the amount of chloride ions that permeate the anion exchange membrane 41 from the second aqueous solution L2 and are supplied to the first aqueous solution L1. (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is higher than a predetermined concentration: The first current and the second current are stopped and the third current is passed simultaneously so as to stop the supply of chloride ions from the second aqueous solution L2 to the first aqueous solution L1. (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 60c is a predetermined concentration: The current ratio of the first current, the second current, and the third current is not changed.

[0169] As described above, the current control unit 60 controls the first current, the second current, and the third current, so that the necessary amount of chloride ions can be supplied to the first aqueous solution L1 stored in the electrolytic cell 10, and the hypochlorous acid concentration in the first aqueous solution L1 can be maintained at a predetermined concentration.

[0170] In the above-mentioned "1. When the first current, the second current, and the third current are simultaneously passed," if there is an increase or decrease in the chloride ion concentration of the first aqueous solution L1, the current ratios of the first current, the second current, and the third current are changed. Because the first current, the second current, and the third current are passed simultaneously, the increase or decrease in the chloride ion concentration of the first aqueous solution L1 can be minimized, and the chloride ion concentration can be maintained at an optimal predetermined concentration.

[0171] In the above-mentioned "2. When the third current is passed at a predetermined value while the first and second currents are controlled," when the chloride ion concentration of the first aqueous solution L1 increases or decreases, the first and second currents are mainly passed or stopped. In the above-mentioned "3. When the first and second currents or the third current are passed," when the chloride ion concentration of the first aqueous solution L1 increases or decreases, either the first and second currents or the third current is passed and the other is stopped. Therefore, the chloride ion concentration of the first aqueous solution L1 can be maintained at a predetermined concentration. In the above-mentioned cases 2 and 3, it is only necessary to control either the first and second currents or the third current, and therefore current control is easy.

[0172] As described above, the chloride ions consumed by the first aqueous solution L1 can be appropriately supplied from the second aqueous solution L2, thereby providing the space purification device 1 capable of stably generating a desired amount of hypochlorous acid gas. Therefore, the space purification device 1 can be provided that can stably generate a desired amount of hypochlorous acid gas for a long period of time, such as one year, without supplying an aqueous solution containing chloride ions from the outside.

[0173] It is also possible to provide a plurality of current control units 60 and control the first current, the second current, and the third current separately.

[0174] Furthermore, if the current control unit 60 does not include the estimation unit 60c, a memory unit may be provided instead of the estimation unit 60c, which stores a correspondence relationship between the decrease in chloride ions due to membraneless electrolysis and the decrease in chloride ions due to salt splashing, and a predetermined time. Based on the memory unit, the current control unit 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 the predetermined time has elapsed.

[0175] When membraneless electrolysis is performed in an electrolytic cell at room temperature and normal pressure, the electrolyte of the first aqueous solution L1 is not used in electrolysis, and oxygen and chlorine are mainly generated from the anode. The electrolyte does not react with hypochlorous acid to reduce the concentration of hypochlorous acid. It is sufficient if the electrolyte has conductivity and is not reactive with the electrodes, the electrolytic cell, or the anion exchange membrane. More specifically, in addition to the first aqueous solution L1 described above, the electrolyte may be, for example, a metal chloride aqueous solution, a hydroxide salt aqueous solution, an acid salt aqueous solution, a phosphate aqueous solution, or a combination thereof. The metal chloride aqueous solution may be, for example, a dilute calcium chloride aqueous solution or a dilute magnesium chloride aqueous solution. The hydroxide salt aqueous solution may be, for example, a dilute sodium hydroxide aqueous solution or a dilute potassium hydroxide aqueous solution of 0.4 wt % (0.1 mol / L) or less. The acid salt aqueous solution may be, for example, a dilute hydrochloric acid aqueous solution of 0.4 wt % (0.1 mol / L) or less. The phosphate aqueous solution may be, 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. As a specific example of a combination of the second aqueous solution L2, the pH may be adjusted by combining a dilute aqueous sodium chloride solution with a dilute aqueous sodium hydroxide solution.

[0176] As described above, the space purification device 1 according to the first embodiment can provide the following effects.

[0177] The space purification device 1 according to this embodiment includes an electrolytic tank 10 that stores a first aqueous solution L1 containing chloride ions and electrolyzes the first aqueous solution L1 to produce hypochlorous acid, a chloride ion supply tank 20 that stores a second aqueous solution L2 containing chloride ions and supplies the chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by passing them through an anion exchange membrane using diaphragm-equipped electrolysis, and a high-concentration chloride aqueous solution supply tank 30 that stores a high-concentration chloride aqueous solution HC that contains chloride ions at a higher concentration than the second aqueous solution L2 and supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2. When replenishing the chloride ions contained in the second aqueous solution L2 that have decreased due to the diaphragm electrolysis, a high-concentration aqueous chloride solution HC is supplied to the second aqueous solution L2 so that the concentration of chloride ions contained in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the concentration of chloride ions in the first aqueous solution L1, and a purification operation is performed in which air introduced from the external space R flows through the electrolytic cell 10 and is released into the external space R together with hypochlorous acid.

[0178] With the above configuration, when replenishing the chloride ions contained in the second aqueous solution L2 that have been reduced by diaphragm electrolysis, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 so that the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1. Therefore, the chloride ions contained in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This provides a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas over a long period of time without supplying an aqueous solution containing chloride ions from an external source. Furthermore, because the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1, the chloride ions contained in the second aqueous solution L2 can be supplied to the first aqueous solution L1 while suppressing water movement between the electrolytic cell 10 and the chloride ion supply tank 20.

[0179] The space purification device 1 according to this embodiment includes a delivery unit 31 that delivers the high-concentration chloride aqueous solution HC from the high-concentration chloride aqueous solution supply tank 30 to the chloride ion supply tank 20. The delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the voltage value applied in the diaphragm electrolysis.

[0180] With the above configuration, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 based on the voltage value applied during membrane electrolysis. Because the voltage value is used, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 so that the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1. Therefore, the chloride ions in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This provides a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas over a long period of time without supplying an aqueous solution containing chloride ions from an external source. Furthermore, because the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1, the chloride ions in the second aqueous solution L2 can be supplied to the first aqueous solution L1 while suppressing water movement between the electrolytic cell 10 and the chloride ion supply tank 20.

[0181] The space purification device 1 according to this embodiment further includes a current control unit 60 that controls the diaphragm-equipped electrolysis. The electrolytic cell 10 has an electrolytic cell-side anode 11, and the chloride ion supply cell 20 has a chloride ion supply cell-side cathode 21. The current control unit 60 has a voltage acquisition unit 60a that acquires the value of the voltage applied between the electrolytic cell-side anode 11 and the chloride ion supply cell-side cathode 21. The delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the voltage value acquired by the voltage acquisition unit 60a.

[0182] With the above configuration, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 based on the voltage value acquired by the voltage acquisition unit 60a. Because the supply is based on the acquired voltage value, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 with greater accuracy so that the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1. Therefore, the chloride ions in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This makes it possible to provide a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from outside.

[0183] The sending unit 31 provided in the space purification device 1 of this embodiment supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the acquired voltage value when the difference between the reference voltage value and the voltage value acquired by the voltage acquisition unit 60a becomes greater than a predetermined change amount.

[0184] With the above configuration, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 based on the voltage value acquired by the voltage acquisition unit 60a. Because the supply is based on the acquired voltage value, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 with greater accuracy so that the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1. Therefore, the chloride ions in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This makes it possible to provide a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from outside.

[0185] The sending unit 31 provided in the space purification device 1 of this embodiment supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the acquired voltage value when the voltage value acquired by the voltage acquisition unit 60a exceeds the reference voltage value.

[0186] With the above configuration, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 based on the voltage value acquired by the voltage acquisition unit 60a. Because the supply is based on the acquired voltage value, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 so that the concentration of chloride ions contained in the second aqueous solution L2 is maintained at a predetermined concentration relative to the concentration of chloride ions in the first aqueous solution L1 with greater accuracy. Therefore, the chloride ions contained in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This makes it possible to provide a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0187] The space purification device 1 according to this embodiment stops the supply of the high-concentration chloride aqueous solution HC to the second aqueous solution L2 when the voltage value acquired by the voltage acquisition unit 60a becomes equal to or lower than the reference voltage value.

[0188] The above configuration prevents the chloride ion concentration in the second aqueous solution L2 from becoming too high. That is, because the voltage value is acquired, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 so that the chloride ion concentration in the second aqueous solution L2 is maintained at a predetermined concentration relative to the chloride ion concentration in the first aqueous solution L1 with higher accuracy. Therefore, the chloride ions in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This allows for the provision of a space purification device 1 that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0189] The current control unit 60 included in the space purification device 1 according to this embodiment further includes a memory unit 60d that stores information relating to the relationship between the voltage value acquired by the voltage acquisition unit 60a and the chloride ion concentration of the second aqueous solution L2, and a supply amount specifying unit that specifies the supply amount of the high-concentration chloride aqueous solution HC based on the voltage value acquired by the voltage acquisition unit 60a and the information stored in the memory unit 60d. The delivery unit 31 supplies the high-concentration chloride aqueous solution HC to the second aqueous solution L2 based on the supply amount specified by the supply amount specifying unit.

[0190] With the above configuration, the supply amount of the high-concentration chloride aqueous solution HC can be specified and supplied to the second aqueous solution L2. Because the supply amount of the high-concentration chloride aqueous solution HC can be specified in advance, the supply of the high-concentration chloride aqueous solution HC can be prevented from causing the chloride ion concentration of the second aqueous solution L2 to become too high. That is, the high-concentration chloride aqueous solution HC can be supplied to the second aqueous solution L2 so that the chloride ion concentration contained in the second aqueous solution L2 is maintained at a predetermined concentration relative to the chloride ion concentration of the first aqueous solution L1. Therefore, the chloride ions contained in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. Therefore, a space purification device 1 can be provided that can stably generate a desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from an external source.

[0191] The current control unit 60 provided in the space purification device 1 of this embodiment passes a current between the electrolytic cell side anode 11 and the chloride ion supply cell side cathode 21 so as to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by electrolysis, thereby causing the chloride ions contained in the second aqueous solution L2 stored in the chloride ion supply cell 20 to pass through the anion exchange membrane 41 and be supplied to the first aqueous solution L1.

[0192] With the above configuration, the current control unit 60 applies the first current so as to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by electrolysis, thereby allowing the chloride ions contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 to pass through the anion exchange membrane 41 and be supplied to the first aqueous solution L1. This eliminates the need to externally supply an aqueous solution containing chloride ions to the electrolytic tank 10 for a long period of time. This makes it possible to provide the space purification device 1 that can stably generate a desired amount of hypochlorous acid gas for a long period of time without externally supplying an aqueous solution containing chloride ions.

[0193] In the space purification device 1 according to this embodiment, the second aqueous solution L2 is a metal chloride aqueous solution containing metal ions and chloride ions. By performing diaphragm electrolysis, the chloride ions contained in the second aqueous solution L2 stored in the chloride ion supply tank 20 are passed through the anion exchange membrane 41 and supplied to the first aqueous solution L1 stored in the electrolytic tank 10 so as to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by the electrolysis. In the chloride ion supply tank 20, the metal ions contained in the second aqueous solution L2 react with the hydroxide ions generated by the diaphragm electrolysis to form a precipitate of metal hydroxide.

[0194] By providing the above configuration, hydroxide ions (OH － ) is used to generate magnesium hydroxide precipitate, thereby generating hydroxide ions (OH － ) and the increase in pH of the second aqueous solution L2 can be suppressed.

[0195] In the space purification device 1 according to this embodiment, within a predetermined range of concentration difference, the concentration of chloride ions contained in the second aqueous solution L2 is maintained lower than the concentration of chloride ions contained in the first aqueous solution L1.

[0196] By providing the above configuration, it is possible to suppress the movement of water from the first aqueous solution L1 to the second aqueous solution L2.

[0197] The space purification device 1 according to this embodiment includes a housing C that houses an electrolytic cell 10, a chloride ion supply tank 20, and a high-concentration chloride aqueous solution supply tank 30. Air supplied to the electrolytic cell 10 in the housing C is released as bubbles B into a first aqueous solution L1, and the released bubbles B are mixed with hypochlorous acid, and the resulting mixed air M is released into an external space R, performing a purification operation.

[0198] With the above configuration, gas-liquid contact is performed in which bubbles B are generated in the first aqueous solution L1 by bubbling. The gas-liquid contact in which bubbles B are generated in the third aqueous solution L3 by bubbling can capture more hypochlorous acid in the bubbles B and release it into the external space R as mixed air M compared to gas-liquid contact between air and the liquid surface S1 of the first aqueous solution L1.

[0199] <Embodiment 2> A space purification device 2 (not shown) according to embodiment 2 differs from the space purification device 1 according to embodiment 1 in the configuration of the high-concentration chloride aqueous solution supply tank 30. Specifically, the space purification device 2 according to embodiment 2 differs from the space purification device 1 according to embodiment 1 in that it includes a chloride agent supply unit 30a (not shown) instead of the high-concentration chloride aqueous solution supply tank 30. The following description will focus on the differences from embodiment 1, and the same components as those in embodiment 1 will be denoted by the same reference numerals and will not be described as appropriate.

[0200] The chloride agent supply unit 30a is a tank for holding a chloride agent CA (not shown) and supplying the chloride agent to the second aqueous solution L2 stored in the chloride ion supply tank 20. As described in the first embodiment, the chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1 stored in the electrolytic tank 10 by the first diaphragm electrolysis and are reduced in concentration. The chloride agent CA is supplied to the second aqueous solution L2 so that the concentration of the chloride ions contained in the second aqueous solution L2 is maintained within a predetermined concentration difference range with respect to the concentration of the chloride ions contained in the first aqueous solution L1.

[0201] Here, if there is a large difference in concentration between the chloride ions contained in the first aqueous solution L1 and the chloride ions contained in the second aqueous solution L2, there is a risk that the water in the first aqueous solution L1 or the second aqueous solution L2 will move to one side through the anion exchange membrane 41 due to osmotic pressure. Therefore, the "predetermined concentration difference," which is the difference in concentration between the chloride ions in the first aqueous solution L1 and the second aqueous solution L2, is a concentration difference within a range in which water movement through the anion exchange membrane 41 is unlikely to occur. "Water movement is unlikely to occur" means that water movement can be suppressed to a degree that prevents water from overflowing from either the electrolytic cell 10 or the chloride ion supply tank 20, even when the space purification device 1 according to this embodiment is used continuously for eight hours every day for one year.

[0202] The chloride agent CA is a substance that is soluble in the second aqueous solution L2 and can supply chloride to the second aqueous solution L2, and is a solid, powder, granular, slurry, or gel-like substance. More specifically, the chloride agent CA is magnesium chloride.

[0203] The chloride agent supply unit 30a includes a supply device 31a (not shown). The supply device 31a supplies the chloride agent CA from the chloride agent supply unit 30a to the chloride ion supply tank 20. The supply device 31a is arranged between the chloride agent supply unit 30a and the chloride ion supply tank 20. The supply device 31a may be any device that can supply the chloride agent CA in a solid, powder, granular, slurry, or gel form to the second aqueous solution L2, and may be, for example, a commercially available powder supply device or a commercially available tablet supply device.

[0204] The supply device 31a included in the chloride agent supply unit 30a supplies the chloride agent CA to the second aqueous solution L2 based on the voltage value applied in the first diaphragm electrolysis (corresponding to "diaphragm electrolysis" in the claims) acquired by the current control unit 60. Based on the acquired second voltage value and information relating to the relationship between the second voltage value and the chloride ion concentration of the second aqueous solution L2 stored in the memory unit 60d included in the current control unit 60, the chloride agent CA is supplied to the second aqueous solution L2 by, for example, the methods of Supply Examples 1 to 3 below.

[0205] Supply Example 1: Supplying the chloride agent CA to the second aqueous solution L2 when the chloride ion concentration in the second aqueous solution L2 has decreased to a predetermined concentration When the difference between the reference voltage value and the second voltage value acquired by the voltage acquisition unit 60a is equal to or greater than a predetermined amount of change, the supply device 31a supplies the chloride agent CA to the second aqueous solution L2 based on the acquired second voltage value. Here, the "reference voltage value" refers to the second voltage value that has a correlation with the initial chloride ion concentration of the first aqueous solution L1 stored in the electrolytic bath 10, i.e., the initial chloride ion concentration at the time when the spatial purification device 1 is first used.

[0206] More specifically, the initial chloride ion concentrations of the first aqueous solution L1 and the second aqueous solution L2 are, for example, 50 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 5%). As the space purification device 1 is used (purification operation), chloride ions contained in the second aqueous solution L2 are supplied to the first aqueous solution L1, thereby decreasing the chloride ion concentration of the second aqueous solution L2 and increasing the second voltage value. As the purification operation continues, the chloride ion concentration of the second aqueous solution L2 decreases. When the voltage acquisition unit 60a acquires a second voltage value that correlates with, for example, a chloride ion concentration of 10 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 1%), the supply device 31a supplies the chloride agent CA to the second aqueous solution L2. In other words, when the second voltage value reaches a predetermined fixed value, the chloride agent CA is supplied to the second aqueous solution L2. When the supply of the chloride agent CA to the second aqueous solution L2 begins, the second voltage value decreases. When the voltage becomes equal to or lower than the reference voltage value acquired by the voltage acquisition unit 60a, the supply of the chloride agent CA to the second aqueous solution L2 is stopped.

[0207] Here, the chloride ion concentration of the first aqueous solution L1 is maintained at a predetermined concentration, as described below. Therefore, the chloride ion concentration of the second aqueous solution L2 can be maintained within a predetermined concentration difference range relative to the chloride ion concentration of the first aqueous solution L1. By maintaining the concentration difference within the predetermined range, water transfer between the first aqueous solution L1 and the second aqueous solution L2 can be suppressed. Note that, within the above-mentioned predetermined concentration difference range, the chloride ion concentration contained in the second aqueous solution L2 may be maintained in a state lower than the chloride ion concentration contained in the first aqueous solution. At this concentration difference, water transfer from the first aqueous solution L1 to the second aqueous solution L2 can be suppressed.

[0208] [Supply Example 2: Maintaining the Chloride Ion Concentration of the Second Aqueous Solution L2 at a Predetermined Concentration] When the second voltage value acquired by the voltage acquisition unit 60a exceeds a reference voltage value, the supply device 31a supplies the chloride agent CA to the second aqueous solution L2 based on the acquired second voltage value. Since the chloride agent CA is supplied to the first aqueous solution L1 at the time when the second voltage value exceeds the reference voltage value, i.e., when the chloride ion concentration of the first aqueous solution L1 decreases, the chloride ion concentration of the second aqueous solution L2 can be maintained at a predetermined concentration.

[0209] Supply Example 3: Supplying the Chloride Agent CA When the Chloride Ion Concentration of the Second Aqueous Solution L2 Decreases by a Predetermined Amount of Change This is similar to Supply Example 1 described above, except that, whereas in Supply Example 1, the chloride agent CA is supplied to the second aqueous solution L2 when the second voltage value reaches a predetermined fixed value, Supply Example 3 is based on a variable amount of change rather than a fixed value. More specifically, the initial chloride ion concentrations of the first aqueous solution L1 and the second aqueous solution L2 are, for example, 50 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 5%). As the purification operation continues, the chloride ion concentration of the second aqueous solution L2 decreases. When the voltage acquisition unit 60a acquires a second voltage value that correlates with, for example, a chloride ion concentration of 10 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 1%), the supply device 31a supplies the chloride agent CA to the second aqueous solution L2.

[0210] Here, the chloride ion concentration of the second aqueous solution L2 to which the chloride agent CA has been supplied may be higher or lower than the initial chloride ion concentration. For example, the chloride ion concentration of the second aqueous solution L2 may be 100 g / L (the mass percent concentration of the dilute sodium chloride aqueous solution is 10%) due to the supply of the chloride agent CA. In this case, the chloride ion concentration of the second aqueous solution L2 may decrease as the purification operation continues, and the next supply of the chloride agent CA may be when the chloride ion concentration of the second aqueous solution L2 has decreased to 60 g / L. In this way, the supply device 31a may supply the chloride agent CA to the second aqueous solution L2 when the chloride ion concentration of the second aqueous solution L2 has decreased to a predetermined concentration difference value, rather than a predetermined fixed value as in Supply Example 1.

[0211] The voltage acquisition unit 60a may further include a supply amount specifying unit (not shown). When the supply amount specifying unit is included, the chloride agent CA may be supplied to the second aqueous solution L2 by a method different from the supply of the chloride agent CA described in Supply Examples 1 to 3. The supply amount of the chloride agent CA to the second aqueous solution L2 is specified based on the second voltage value acquired by the voltage acquisition unit 60a and the information stored in the memory unit 60d. The supply device 31a supplies the chloride agent CA to the second aqueous solution L2 at the supply amount specified by the supply amount specifying unit. By supplying this supply amount of the chloride agent CA to the second aqueous solution L2, the chloride ion concentration of the second aqueous solution L2 is maintained at a predetermined concentration. Therefore, the chloride ion concentration of the second aqueous solution L2 can be maintained within a predetermined concentration difference range relative to the chloride ion concentration of the first aqueous solution L1.

[0212] As described above, the space purification device 2 according to the second embodiment can provide the following effects.

[0213] The space purification device 2 according to this embodiment includes an electrolytic tank 10 that stores a first aqueous solution L1 containing chloride ions and electrolyzes the first aqueous solution L1 to produce hypochlorous acid, a chloride ion supply tank 20 that stores a second aqueous solution L2 containing chloride ions and supplies the chloride ions contained in the second aqueous solution L2 to the first aqueous solution L1 by passing them through an anion exchange membrane using diaphragm-equipped electrolysis, and a chloride agent supply unit 30a that holds a chloride agent CA containing a higher concentration of chloride ions than the second aqueous solution L2 and supplies the chloride agent CA to the second aqueous solution L2. When replenishing the chloride ions contained in the second aqueous solution L2 that have decreased due to the diaphragm electrolysis, a chloride agent CA is supplied to the second aqueous solution L2 so that the concentration of the chloride ions contained in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the concentration of chloride ions in the first aqueous solution L1, and a purification operation is performed in which air introduced from the external space R flows through the electrolytic cell 10 and is released into the external space R together with hypochlorous acid.

[0214] With the above configuration, when replenishing the chloride ions contained in the second aqueous solution L2 that have been reduced by diaphragm electrolysis, the chloride agent CA can be supplied to the second aqueous solution L2 so that the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1. Therefore, the chloride ions contained in the second aqueous solution L2 can be stably supplied to the first aqueous solution L1. This provides a space purification device 2 that can stably generate a desired amount of hypochlorous acid gas over a long period of time without supplying an aqueous solution containing chloride ions from an external source. Furthermore, because the chloride ion concentration in the second aqueous solution L2 is maintained within a predetermined concentration difference range relative to the chloride ion concentration in the first aqueous solution L1, the chloride ions contained in the second aqueous solution L2 can be supplied to the first aqueous solution L1 while suppressing water movement between the electrolytic cell 10 and the chloride ion supply tank 20.

[0215] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present disclosure.

[0216] An outline of one aspect of the present disclosure is as follows.

[0217] (Item 1) A space purification device comprising: an electrolytic cell that stores a first aqueous solution containing chloride ions and electrolyzes the first aqueous solution to produce hypochlorous acid; a chloride ion supply tank that stores a second aqueous solution containing chloride ions and supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by permeating an anion exchange membrane using diaphragm electrolysis; and a high-concentration chloride aqueous solution supply tank that stores a high-concentration chloride aqueous solution that contains chloride ions at a higher concentration than the second aqueous solution and supplies the high-concentration chloride aqueous solution to the second aqueous solution, wherein, when compensating for chloride ions contained in the second aqueous solution that have decreased due to the diaphragm electrolysis, the high-concentration chloride aqueous solution is supplied to the second aqueous solution so that the concentration of the chloride ions contained in the second aqueous solution is maintained within a predetermined concentration difference range with respect to the chloride ion concentration of the first aqueous solution, and wherein a purification operation is performed in which air introduced from an external space flows through the electrolytic cell and is released into the external space together with the hypochlorous acid.

[0218] (Item 2) The space purification device according to Item 1, further comprising a delivery unit that delivers the high-concentration chloride aqueous solution from the high-concentration chloride aqueous solution supply tank to the chloride ion supply tank, wherein the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on a voltage value applied in the diaphragm-equipped electrolysis.

[0219] (Item 3) The space purification device according to Item 2, further comprising a current control unit that controls the diaphragm-equipped electrolysis, wherein the electrolytic cell has an electrolytic cell-side anode, the chloride ion supply cell has a supply cell-side cathode, the current control unit has a voltage acquisition unit that acquires a voltage value applied between the electrolytic cell-side anode and the supply cell-side cathode, and the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the voltage value acquired by the voltage acquisition unit.

[0220] (Item 4) The space purification device according to Item 3, wherein when a difference between a reference voltage value and the voltage value acquired by the voltage acquisition unit is equal to or greater than a predetermined change amount, the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the acquired voltage value.

[0221] (Item 5) The space purification device according to Item 3, wherein when the voltage value acquired by the voltage acquisition unit exceeds a reference voltage value, the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the acquired voltage value.

[0222] (Item 6) The space purification device according to Item 4 or 5, wherein the supply of the high-concentration chloride aqueous solution to the second aqueous solution is stopped when the voltage value acquired by the voltage acquisition unit becomes equal to or less than the reference voltage value.

[0223] (Item 7) The space purification device according to Item 3, wherein the current control unit further includes: a memory unit that stores information relating to a relationship between the voltage value acquired by the voltage acquisition unit and the chloride ion concentration of the second aqueous solution; and a supply amount specifying unit that specifies a supply amount of the high-concentration chloride aqueous solution based on the voltage value acquired by the voltage acquisition unit and the information stored in the memory unit; and the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the supply amount specified by the supply amount specifying unit.

[0224] (Item 8) The space purification device according to Item 3, wherein the current control unit supplies chloride ions contained in the second aqueous solution stored in the chloride ion supply tank to the first aqueous solution by passing a current between the electrolytic cell-side anode and the supply cell-side cathode so as to replenish chloride ions contained in the first aqueous solution that have been reduced by the electrolysis, through the anion exchange membrane.

[0225] (Item 9) The space purification device according to Item 1, wherein the second aqueous solution is a metal chloride aqueous solution containing metal ions and the chloride ions, and wherein by performing the membrane-operated electrolysis, the chloride ions contained in the second aqueous solution stored in the chloride ion supply tank are supplied to the first aqueous solution stored in the electrolytic tank through the anion exchange membrane so as to replenish the chloride ions contained in the first aqueous solution that have been reduced by the electrolysis, and the metal ions contained in the second aqueous solution and hydroxide ions generated by the membrane-operated electrolysis react with each other in the chloride ion supply tank to form a precipitate of metal hydroxide.

[0226] (Item 10) The space purification device according to Item 1, wherein the concentration of the chloride ions contained in the second aqueous solution is maintained lower than the concentration of the chloride ions contained in the first aqueous solution within the predetermined range of concentration difference.

[0227] (Item 11) The space purification device according to Item 1, comprising a housing that houses the electrolytic cell, the chloride ion supply tank, and the high-concentration chloride aqueous solution supply tank, wherein a purification operation is performed in which the air supplied to the electrolytic cell within the housing is released as bubbles into the first aqueous solution, the released bubbles are mixed with the hypochlorous acid, and the resulting mixed air is released into the external space.

[0228] (Item 12) A space purification device comprising: an electrolytic cell that stores a first aqueous solution containing chloride ions and electrolyzes the first aqueous solution to produce hypochlorous acid; a chloride ion supply tank that stores a second aqueous solution containing chloride ions and supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by permeating an anion exchange membrane using diaphragm electrolysis; and a chloride agent supply unit that holds a chloride agent containing a higher concentration of chloride ions than the second aqueous solution and supplies the chloride agent to the second aqueous solution, wherein, when compensating for chloride ions contained in the second aqueous solution that have decreased due to the diaphragm electrolysis, the chloride agent is supplied to the second aqueous solution so that the concentration of the chloride ions contained in the second aqueous solution is maintained within a predetermined concentration difference range with respect to the chloride ion concentration of the first aqueous solution, and a purification operation is performed in which air introduced from an external space flows through the electrolytic cell and is released into the external space together with the hypochlorous acid.

[0229] DESCRIPTION OF SYMBOLS 1, 2 Space purification device 10 Electrolytic cell 11 Electrolytic cell-side anode 12 Electrolytic cell-side cathode 13 Air supply unit 14 Air blower duct 15 Electrolytic cell-side internal space 16 Water recovery unit 17 Discharge port 18 Water level detection unit 20 Chloride ion supply tank 21 Chloride ion supply tank-side cathode 22 Chloride ion supply tank-side internal space 23 First outlet 30 High-concentration chloride aqueous solution supply tank 30a Chloride agent supply unit 31 Delivery unit 31a Supply device 32 Suction side tube 33 Dripping side tube 41 Anion exchange membrane 42 Cation exchange membrane 50 Metal ion supply tank 51 Metal ion supply tank-side anode 52 Metal ion supply tank-side internal space 53 Second outlet 60 Current control unit 60a Voltage acquisition unit 60b Calculation unit 60c Estimation unit 60d Storage section 61 Wiring 62 Wiring 63 Wiring 64 Wiring A Air flow path B Bubbles C Housing CA Chloride agent E1 First diaphragm electrolysis section E2 Second diaphragm electrolysis section E2a Second diaphragm electrolysis section E2b Second diaphragm electrolysis section E3 Non-diaphragm electrolysis section HC High concentration chloride aqueous solution L1 First aqueous solution L2 Second aqueous solution L3 Third aqueous solution M Mixed air R External space S1 Liquid level S2 Liquid level S3 Liquid level

Claims

1. A space purification device comprising: an electrolytic cell that stores a first aqueous solution containing chloride ions and electrolyzes the first aqueous solution to produce hypochlorous acid; a chloride ion supply tank that stores a second aqueous solution containing chloride ions and supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by passing them through an anion exchange membrane using diaphragm electrolysis; and a high-concentration chloride aqueous solution supply tank that stores a high-concentration chloride aqueous solution containing a higher concentration of chloride ions than the second aqueous solution and supplies the high-concentration chloride aqueous solution to the second aqueous solution, wherein, when compensating for chloride ions contained in the second aqueous solution that have decreased due to the diaphragm electrolysis, the high-concentration chloride aqueous solution is supplied to the second aqueous solution so that the concentration of the chloride ions contained in the second aqueous solution is maintained within a predetermined concentration difference range from the chloride ion concentration of the first aqueous solution, and a purification operation is performed in which air introduced from an external space flows through the electrolytic cell and is released into the external space together with the hypochlorous acid.

2. The space purification device according to claim 1, further comprising a delivery unit that delivers the high-concentration chloride aqueous solution from the high-concentration chloride aqueous solution supply tank to the chloride ion supply tank, and the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the voltage value applied in the diaphragm electrolysis.

3. The space purification device according to claim 2, further comprising a current control unit that controls the diaphragm-equipped electrolysis, wherein the electrolytic cell has an electrolytic cell-side anode, the chloride ion supply cell has a supply cell-side cathode, the current control unit has a voltage acquisition unit that acquires a voltage value applied between the electrolytic cell-side anode and the supply cell-side cathode, and the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the voltage value acquired by the voltage acquisition unit.

4. The space purification device according to claim 3, wherein the sending unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the acquired voltage value when the difference between a reference voltage value and the voltage value acquired by the voltage acquisition unit becomes equal to or greater than a predetermined amount of change.

5. The space purification device according to claim 3, wherein the sending unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the acquired voltage value when the voltage value acquired by the voltage acquisition unit exceeds a reference voltage value.

6. The space purification device according to claim 4 or 5, wherein the supply of the high-concentration chloride aqueous solution to the second aqueous solution is stopped when the voltage value acquired by the voltage acquisition unit becomes equal to or lower than the reference voltage value.

7. The space purification device described in claim 3, wherein the current control unit further comprises: a memory unit that stores information regarding the relationship between the voltage value acquired by the voltage acquisition unit and the chloride ion concentration of the second aqueous solution; and a supply amount determination unit that determines the supply amount of the high-concentration chloride aqueous solution based on the voltage value acquired by the voltage acquisition unit and the information stored in the memory unit; and the delivery unit supplies the high-concentration chloride aqueous solution to the second aqueous solution based on the supply amount determined by the supply amount determination unit.

8. The space purification device described in claim 3, wherein the current control unit supplies chloride ions contained in the second aqueous solution stored in the chloride ion supply tank to the first aqueous solution by passing a current between the electrolytic cell side anode and the supply cell side cathode so as to replenish chloride ions contained in the first aqueous solution that have been reduced by the electrolysis, through the anion exchange membrane.

9. The space purification device according to claim 1, wherein the second aqueous solution is a metal chloride aqueous solution containing metal ions and the chloride ions, and wherein by performing the membrane electrolysis, the chloride ions contained in the second aqueous solution stored in the chloride ion supply tank are supplied to the first aqueous solution stored in the electrolytic tank through the anion exchange membrane so as to replenish the chloride ions contained in the first aqueous solution that have been reduced by the electrolysis, and within the chloride ion supply tank, the metal ions contained in the second aqueous solution react with the hydroxide ions produced by the membrane electrolysis to form a precipitate of metal hydroxide.

10. The spatial purification device according to claim 1, wherein, within the range of the predetermined concentration difference, the concentration of the chloride ions contained in the second aqueous solution is maintained lower than the concentration of the chloride ions contained in the first aqueous solution.

11. The space purification device according to claim 1, comprising a housing that houses the electrolytic cell, the chloride ion supply tank, and the high-concentration chloride aqueous solution supply tank, wherein the air supplied to the electrolytic cell within the housing is released as bubbles into the first aqueous solution, the released bubbles are mixed with the hypochlorous acid, and the resulting mixed air is released into the external space during purification operation.

12. A space purification device comprising: an electrolytic cell that stores a first aqueous solution containing chloride ions and electrolyzes the first aqueous solution to produce hypochlorous acid; a chloride ion supply tank that stores a second aqueous solution containing chloride ions and supplies the chloride ions contained in the second aqueous solution to the first aqueous solution by passing them through an anion exchange membrane using diaphragm electrolysis; and a chloride agent supply unit that holds a chloride agent containing a higher concentration of chloride ions than the second aqueous solution and supplies the chloride agent to the second aqueous solution, wherein, when compensating for chloride ions contained in the second aqueous solution that have decreased due to the diaphragm electrolysis, the chloride agent is supplied to the second aqueous solution so that the concentration of the chloride ions contained in the second aqueous solution is maintained within a predetermined concentration difference range from the chloride ion concentration of the first aqueous solution, and a purification operation is performed in which air introduced from an external space flows through the electrolytic cell and is released into the external space together with the hypochlorous acid.

Images