Space purification device

Abstract

This space purification device (1) comprises: an electrolysis tank (10) for storing a first aqueous solution (L1); a first supply tank (20a) for storing a second aqueous solution (L2) and supplying OH− to the first aqueous solution (L1); a second supply tank (20b) for storing a third aqueous solution (L3) and supplying Cl− to the first aqueous solution (L1); a first anion exchange membrane (30a) connecting the electrolysis tank (10) and the first supply tank (20a); a second anion exchange membrane (30b) connecting the electrolytic cell (10) and the second supply tank (20b); and a current control unit that controls an electric current so as to compensate for Cl− that decreases when the first aqueous solution (L1) and the second aqueous solution (L2) are subjected to first diaphragm electrolysis to generate hypochlorous acid, thereby causing Cl− contained in the third aqueous solution (L3) to be transmitted through the second anion exchange membrane (30b) and supplied to 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 removes bacteria, fungi, viruses, odors, and the like from the air using hypochlorous acid generated by electrolyzing an aqueous solution containing chloride ions.

[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 has been made in consideration of the above-mentioned problems, and 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.

[0006] The spatial purification device according to the present disclosure includes an electrolytic cell for storing a first aqueous solution containing chloride ions, a first supply tank for storing a second aqueous solution containing hydroxide ions and supplying hydroxide ions to the first aqueous solution, a second supply tank for storing a third aqueous solution containing chloride ions at a higher concentration than the first aqueous solution and supplying chloride ions to the first aqueous solution, an electrolytic cell-side anode provided in the electrolytic cell, a first supply tank-side cathode provided in the first supply tank, a second supply tank-side cathode provided in the second supply tank, a first anion exchange membrane connecting the electrolytic cell and the first supply tank to be permeable to anions based on a voltage applied between the electrolytic cell-side anode and the first supply tank-side cathode, and a second anion exchange membrane connecting the electrolytic cell and the second supply tank to be permeable to anions based on a voltage applied between the electrolytic cell-side anode and the second supply tank-side cathode. a first membrane-with-diaphragm electrolysis section provided between the electrolytic cell and the first supply cell, which performs first membrane-with-diaphragm electrolysis of the first aqueous solution and the second aqueous solution via the first anion exchange membrane by passing a first current between the electrolytic cell-side anode and the first supply cell-side cathode to produce hypochlorous acid in the electrolytic cell; a second membrane-with-diaphragm electrolysis section provided between the electrolytic cell and the second supply cell, which performs second membrane-with-diaphragm electrolysis via the second anion exchange membrane by passing a second current between the electrolytic cell-side anode and the second supply cell-side cathode; and a current control section which controls the second current so as to compensate for chloride ions contained in the first aqueous solution that have been reduced by the first membrane-with-diaphragm electrolysis, thereby allowing chloride ions contained in the third aqueous solution to pass through the second anion exchange membrane and be supplied to the first aqueous solution.

[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 side cross-sectional view showing a space purification device according to embodiment 1. Fig. 2 is a top view showing the space purification device of Fig. 1. Fig. 3 is a diagram showing the chemical reaction formulas occurring in the first diaphragm electrolysis section and the second diaphragm electrolysis section formed by the respective tanks of the space purification device. Fig. 4 is a diagram showing the chemical reaction formulas occurring in the first diaphragm electrolysis section and the second diaphragm electrolysis section formed by the respective tanks of the space purification device. Fig. 5 is a block diagram showing a current control section forming part of the space purification device.

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

[0010] The right-handed xyz coordinate system shown in Figures 1 and 2 is for the convenience of explaining the positional relationship of the components. Unless otherwise specified, the positive direction of the z axis is the vertically upward direction. The xy plane is a horizontal plane, and is common to all the drawings.

[0011] First Embodiment A space purification device 1 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 and 2 .

[0012] Fig. 1 is a side cross-sectional view showing a space purification device 1 according to embodiment 1. Fig. 2 is a top view showing the space purification device 1 of Fig. 1 .

[0013] (1. Overall Configuration) The space purification device 1 generates hypochlorous acid by electrolyzing a first aqueous solution L1 containing chloride ions in an electrolytic cell 10 described below, and then volatilizes the generated hypochlorous acid. The space purification device 1 removes bacteria, fungi, viruses, odors, and the like contained in the air in the external space of the space purification device 1 by discharging the volatilized hypochlorous acid into the external space of a housing (not shown) that constitutes the space purification device 1.

[0014] 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 includes, for example, inside an air conditioner, around an electric fan, around a circulator, around a ceiling fan, inside a humidifier, inside an air purifier, on a desk, etc.

[0015] As shown in FIGS. 1 and 2, the spatial purification device 1 includes an electrolytic cell 10, a first supply cell 20a, a second supply cell 20b, a first anion exchange membrane 30a, a second anion exchange membrane 30b, and a current control unit 40.

[0016] The electrolytic cell 10, the first supply tank 20a, the second supply tank 20b, the first anion exchange membrane 30a, the second anion exchange membrane 30b, and the current control unit 40 are housed in a housing (not shown). That is, the space purification device 1 may be a unit integrated into the housing. The shape of the housing 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 housed inside an air conditioner, for example, approximately 10 cm x 7 cm x 4 cm.

[0017] The electrolytic bath 10 is a bath for storing a first aqueous solution L1 containing chloride ions. The electrolytic bath 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 bath 10. The first aqueous solution L1 is, for example, a dilute sodium chloride aqueous solution or a dilute potassium chloride aqueous solution having a predetermined chloride ion concentration.

[0018] The "predetermined chloride ion concentration" of the first aqueous solution L1 includes both a chloride ion concentration having a predetermined numerical range and a chloride ion concentration having a predetermined numerical value. More specifically, the chloride ion concentration of the first aqueous solution L1 may be, for example, 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 dilute potassium chloride aqueous solution may be, for example, 0.1% to 5%, or may be 1%. 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 at the same time.

[0019] The first supply tank 20a is a tank for storing a second aqueous solution L2 containing hydroxide ions. The hydroxide ions contained in the second aqueous solution L2 in the first supply tank 20a pass through the first anion exchange membrane 30a and are supplied to the first aqueous solution L1 in the electrolytic cell 10. The electrolytic cell 10, the first supply tank 20a, and the first anion exchange membrane 30a described below may be collectively referred to as a "diaphragm-equipped electrolytic cell."

[0020] The first supply tank 20a is a tank for storing a second aqueous solution L2 containing hydroxide ions and supplying the hydroxide ions to the first aqueous solution L1. FIG. 1 shows the first supply tank 20a storing the second aqueous solution L2. The second aqueous solution L2 is, for example, a sodium hydroxide aqueous solution. More specifically, the second aqueous solution L2 may be, for example, a sodium hydroxide aqueous solution having a mass percent concentration of sodium hydroxide of 0.1% to 5%, or may be a 1% sodium hydroxide aqueous solution. It is more preferable that the second aqueous solution L2 contain sodium chloride or potassium chloride so that the molar concentration of the second aqueous solution L2 is the same as that of the metal cations (sodium ions or potassium ions) contained in the first aqueous solution L1.

[0021] The second supply tank 20b is a tank for storing a third aqueous solution L3 containing chloride ions. The chloride ions contained in the third aqueous solution L3 in the second supply tank 20b permeate through the second anion exchange membrane 30b and are supplied to the first aqueous solution L1 in the electrolytic bath 10.

[0022] The second supply tank 20b is a tank for storing a third aqueous solution L3 containing chloride ions and for supplying chloride ions to the first aqueous solution L1. FIG. 1 shows a state in which the third aqueous solution L3 is stored in the second supply tank 20b. The chloride ion concentration of the third aqueous solution L3 is higher than the chloride ion concentration of the first aqueous solution L1. The third aqueous solution L3 is, for example, a high-concentration hydrochloric acid aqueous solution. More specifically, the third aqueous solution L3 is, for example, a hydrochloric acid aqueous solution with a mass percent concentration of 10% to 25%.

[0023] It is more preferable that the third aqueous solution L3 contains sodium chloride or potassium chloride at the same mass percent concentration (meaning the mass percent concentration relative to the solvent mass excluding the mass of hydrochloric acid contained in the third aqueous solution L3) as the sodium chloride or potassium chloride contained in the first aqueous solution L1. In other words, it is preferable that the third aqueous solution L3 contains metal cations (sodium ions or potassium ions) at the same molar concentration as the metal cations (sodium ions or potassium ions) contained in the first aqueous solution L1. Note that the "same molar concentration" does not necessarily mean the same molar concentration, but may be a molar concentration at which the difference in concentration between the metal cations (sodium ions or potassium ions) contained in the third aqueous solution L3 and the first aqueous solution L1 is smaller than a predetermined threshold range.

[0024] This prevents metal cations (sodium ions or potassium ions) contained in the first aqueous solution L1 from permeating through the second anion exchange membrane 30b into the third aqueous solution L3, which is particularly noticeable when there is a large difference in the concentration of metal cations between the aqueous solutions passing through the anion exchange membranes.

[0025] Assuming continuous use for eight hours a day for one year, the respective volumes of the electrolytic cell 10 and the second supply cell 20b are preferably set such that, for example, the volume of the second supply cell 20b is at least approximately 12 times the volume of the electrolytic cell 10. This volume ratio allows the second supply cell 20b to store a third aqueous solution L3 containing a sufficient amount of chloride ions required to be supplied to the first aqueous solution L1 of the electrolytic cell 10. Therefore, chloride ions can be stably supplied from the third aqueous solution L3 stored in the second supply cell 20b to the first aqueous solution L1 stored in the electrolytic cell 10. The amount of the first aqueous solution L1 stored in the electrolytic cell 10 is, for example, approximately 2 mL to 10 mL. The volume of the first supply cell 20a is approximately the same as that of the electrolytic cell 10, and the amount of the second aqueous solution L2 stored in the first supply cell 20a is, for example, approximately 2 mL to 10 mL.

[0026] The first anion exchange membrane 30a is a membranous member that connects the electrolytic cell 10 and the first supply cell 20a in a manner that allows anions to pass therethrough, based on a voltage applied between the electrolytic cell 10 and the first supply cell 20a. More specifically, when a voltage is applied between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12 (described below), first membrane-with-diaphragm electrolysis is carried out via the first anion exchange membrane 30a. By the first membrane-with-diaphragm electrolysis using the electrolytic cell-side anode 11 and the first supply cell-side cathode 12, hydroxide ions contained in the second aqueous solution L2 permeate the first anion exchange membrane 30a and are supplied to the first aqueous solution L1 (positive direction of the x-axis, indicated by the bold black arrow on the left side in FIG. 1 ).

[0027] The first anion exchange membrane 30a in this embodiment is not a type of anion exchange membrane through which anions permeate due to osmotic pressure without using electricity. Furthermore, the first anion exchange membrane 30a does not allow sodium ions, which are cations, to permeate. More specifically, when hydroxide ions contained in the second aqueous solution L2 permeate the first anion exchange membrane 30a and are supplied to the first aqueous solution L1 by the first membrane-with-diaphragm electrolysis using the electrolytic cell-side anode 11 and the first supply cell-side cathode 12, sodium ions, which are cations, do not permeate the first anion exchange membrane 30a. The first anion exchange membrane 30a is, for example, a hydrocarbon-based anion exchange membrane, and includes membranes that have monovalent anion-selective permeability, alkali resistance, and high-temperature resistance.

[0028] The first anion exchange membrane 30a is disposed between the electrolytic cell 10 and the first supply cell 20a. For example, the surface of the electrolytic cell 10 facing the first supply cell 20a (the yz plane on the negative side of the x-axis) and the surface of the first supply cell 20a facing the electrolytic cell 10 (the yz plane on the positive side of the x-axis) may each be formed by a frame-shaped member. When the surfaces of the electrolytic cell 10 and the first supply cell 20a facing each other are formed by frame-shaped members, the first anion exchange membrane 30a may be disposed so as to be fitted into the frame-shaped member.

[0029] The second anion exchange membrane 30b is a membranous member that connects the electrolytic cell 10 and the second supply cell 20b in a manner that allows anions to pass therethrough, based on a voltage applied between the electrolytic cell 10 and the second supply cell 20b. More specifically, when a voltage is applied between the electrolytic cell-side anode 11 and the second supply cell-side cathode 21 (described below), second membrane-with-diaphragm electrolysis is performed via the second anion exchange membrane 30b. By the second membrane-with-diaphragm electrolysis using the electrolytic cell-side anode 11 and the second supply cell-side cathode 21, chloride ions contained in the third aqueous solution L3 permeate through the second anion exchange membrane 30b and are supplied to the first aqueous solution L1 (negative direction of the x-axis, indicated by a bold black arrow on the right side in FIG. 1 ).

[0030] The second anion exchange membrane 30b in this embodiment is not a type of anion exchange membrane through which anions permeate due to osmotic pressure without using electricity. Furthermore, the second anion exchange membrane 30b does not allow sodium ions, which are cations, to permeate. More specifically, when chloride ions contained in the third aqueous solution L3 permeate the second anion exchange membrane 30b and are supplied to the first aqueous solution L1 by the second membrane electrolysis using the electrolytic cell-side anode 11 and the second supply cell-side cathode 21, sodium ions, which are cations, do not permeate the second anion exchange membrane 30b. The second anion exchange membrane 30b is, for example, a hydrocarbon-based anion exchange membrane, and includes membranes that have monovalent anion-selective permeability, alkali resistance, and high-temperature resistance.

[0031] The second anion exchange membrane 30b is disposed between the electrolytic cell 10 and the second supply cell 20b. For example, the surface of the electrolytic cell 10 facing the second supply cell 20b (the yz plane on the positive side of the x-axis) and the surface of the second supply cell 20b facing the electrolytic cell 10 (the yz plane on the negative side of the x-axis) may each be formed by a frame-shaped member. When the surfaces of the electrolytic cell 10 and the second supply cell 20b facing each other are formed by frame-shaped members, the second anion exchange membrane 30b may be disposed so as to be fitted into the frame-shaped member.

[0032] The current control unit 40 controls the current used in the first diaphragm electrolysis and the second diaphragm electrolysis. More specifically, the current control unit 40 controls the current used in the first diaphragm electrolysis, which is carried out across the electrolytic cell 10 and the first supply cell 20a, via the first anion exchange membrane 30a using the electrolytic cell-side anode 11 arranged in the electrolytic cell 10 and the first supply cell-side cathode 12 arranged in the first supply cell 20a. The current control unit 40 also controls the current used in the second diaphragm electrolysis, which is carried out across the electrolytic cell 10 and the second supply cell 20b, via the second anion exchange membrane 30b using the electrolytic cell-side anode 11 arranged in the electrolytic cell 10 and the second supply cell-side cathode 21 arranged in the second supply cell 20b.

[0033] The electrolytic cell-side anode 11 is used in both the first diaphragm electrolysis and the second diaphragm electrolysis. That is, the space purification device 1 according to this embodiment has one anode and two cathodes, for a total of three electrodes. Because the first supply tank 20a and the second supply tank 20b each have only cathodes, chlorine is not generated in the first supply tank 20a and the second supply tank 20b by a chemical reaction described below.

[0034] Hereinafter, the details of each tank (electrolytic tank 10, first supply tank 20a, second supply tank 20b) constituting the space purification device 1 will be described in more detail with reference to FIGS.

[0035] (2. Electrolytic Cell) The electrolytic cell 10 includes an electrolytic cell-side anode 11 , wiring 13 , an inlet 15 , a mixing space 16 , and an outlet 17 .

[0036] The electrolytic cell-side anode 11 is an electrode paired with a first supply cell-side cathode 12 disposed in the first supply cell 20a and used to electrolyze the first aqueous solution L1. As shown in FIG. 1 , a first anion-exchange membrane 30a is disposed between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12. That is, the electrolysis of the first aqueous solution L1 and the second aqueous solution L2 performed using the pair of the electrolytic cell-side anode 11 and the first supply cell-side cathode 12 is membrane-operated electrolysis (first membrane-operated electrolysis). The first membrane-operated electrolysis of the first aqueous solution L1 performed using the pair of the electrolytic cell-side anode 11 and the first supply cell-side cathode 12 generates hypochlorous acid, which is used for space purification.

[0037] The electrolytic cell-side anode 11 has a plate-like shape. That is, the electrolytic cell-side anode 11 is an anode plate having a plate-like shape that is placed on the electrolytic cell 10 side. The plate-like shape includes a rectangular or oblong shape. Hereinafter, the electrolytic cell-side anode 11 may also be referred to as an "electrolytic cell-side anode plate."

[0038] As an example, a case where the plate shape of the electrolytic cell-side anode 11 is rectangular will be described. As shown in Fig. 1 , the electrolytic cell-side anode 11 is arranged such that the shorter side of the rectangle is aligned with the vertical direction (z-axis direction). This arrangement can prevent bubbles generated by chemical reactions from adhering to both sides of the rectangular electrode. Furthermore, compared to when the longer side of the rectangle is aligned with the vertical direction (z-axis direction), when the shorter side is aligned with the vertical direction (z-axis direction), bubbles generated at the lower part of the electrolytic cell-side anode 11 (negative side of the z-axis) can be prevented from adhering to the upper part of the electrolytic cell-side anode 11 (positive side of the z-axis).

[0039] 2 , the electrolytic cell side anode 11 is arranged such that the longitudinal direction of the rectangle is along the horizontal direction (y-axis direction). The first supply cell side cathode 12 is also arranged in the same manner as the electrolytic cell side anode 11, as will be described in detail later. In other words, the electrolytic cell side anode 11 and the first supply cell side cathode 12 are arranged such that the planes (yz planes) of their respective rectangles face each other with a predetermined distance between them. The predetermined distance is a distance suitable for electrolysis performed using a pair of the electrolytic cell side anode 11 and the first supply cell side cathode 12.

[0040] The electrolytic cell-side anode 11 includes an electrolytic cell-side anode plate immersion portion 11a and an electrolytic cell-side anode plate protrusion portion 11b.

[0041] The electrolytic cell-side anode 11 is inserted from the outside of the electrolytic cell 10 toward the inside. In FIG. 2 , as an example, the electrolytic cell-side anode 11 is inserted horizontally (in the y-axis direction) from the side of the electrolytic cell 10 (the xz plane side on the negative side of the y-axis). The electrolytic cell-side anode plate immersed portion 11a inserted into the electrolytic cell 10 is the portion of the electrolytic cell-side anode 11 that is located inside the electrolytic cell 10 and is entirely immersed in the first aqueous solution L1. In other words, the first aqueous solution L1 is stored in the electrolytic cell 10 so that the entire electrolytic cell-side anode plate immersed portion 11a is immersed. That is, the first aqueous solution L1 is stored in the electrolytic cell 10 so that the liquid level S1 of the first aqueous solution L1 exceeds the upper end (the end on the positive side of the z-axis) of the electrolytic cell-side anode plate immersed portion 11a.

[0042] The electrolytic cell-side anode plate protrusion 11b is the portion of the electrolytic cell-side anode 11 that is arranged on the outside of the electrolytic cell 10. The wiring 13 is a line through which current flows. The electrolytic cell-side anode plate protrusion 11b is electrically connected to the current control unit 40 via the wiring 13.

[0043] As the electrolytic cell-side anode 11, for example, a platinum-iridium-titanium electrode, a platinum electrode, a ruthenium-titanium electrode, an iridium-titanium oxide electrode, or the like may be used.

[0044] The inlet 15 is an opening through which air from the space outside the housing constituting the space purification device 1 flows in. That is, the inlet 15 is an opening through which air from the space outside the space purification device 1 flows in. In FIG. 1 , the inlet 15 is provided on the top surface of the electrolytic cell 10 (xy plane on the positive side of the z axis) as an example, but the inlet 15 may be located above the liquid level S1 of the first aqueous solution L1. The shape of the inlet 15 may be, for example, cylindrical as shown in FIG. 2 or rectangular tubular.

[0045] The mixing space 16 is a space formed above the electrolytic cell 10 (positive side of the z-axis) when the first aqueous solution L1 is stored in the electrolytic cell 10. The mixing space 16 is a space for mixing hypochlorous acid generated by the first diaphragm electrolysis of the first aqueous solution L1 using a pair of electrolytic cell-side anodes 11 and first supply cell-side cathodes 12 with air from the external space that flows in through the inlet 15. The hypochlorous acid generated by the first diaphragm electrolysis includes volatilized and gasified hypochlorous acid gas and hypochlorous acid dissolved in the first aqueous solution L1. The hypochlorous acid gas is contained in the air that flows in through the inlet 15 and flows out to the external space through the outlet 17, which will be described later. The hypochlorous acid dissolved in the first aqueous solution L1 flows out to the external space through the outlet 17, which will be described later, by gas-liquid contact with the air that flows in through the inlet 15.

[0046] The outlet 17 is an opening for discharging mixed air, which is a mixture of air flowing in from the inlet 15 and hypochlorous acid generated by the first diaphragm electrolysis of the first aqueous solution L1, into the space outside the housing. That is, the outlet 17 is an opening for discharging mixed air into the space outside the space purification device 1. In FIG. 1 , the outlet 17 is provided on the upper surface of the electrolytic cell 10 (the x-y plane on the positive side of the z-axis) as an example, similar to the inlet 15, but the outlet 17 may be located above the liquid level S1 of the first aqueous solution L1. The shape of the outlet 17 is similar to that of the inlet 15 and may be, for example, cylindrical as shown in FIG. 2 or rectangular tubular.

[0047] The inlet 15 and the outlet 17 may each be provided with a lid (not shown) that can be opened or closed or that can be removed. The lid may be configured to be closed when the space purification device 1 is transported or moved, and to be opened or removed when the space purification device 1 is used. Furthermore, although the inlet 15 and the outlet 17 have been described as having separate structures, the inlet 15 and the outlet 17 may each serve as both an inlet and an outlet depending on the direction of the wind flowing into the space purification device 1.

[0048] The air containing hypochlorous acid that flows out from the outlet 17 into the space outside the space purification device 1 purifies the space. That is, the air containing hypochlorous acid removes bacteria, fungi, viruses, odors, and the like contained in the air in the space outside the housing.

[0049] (3. First Supply Tank) The first supply tank 20a includes a first supply tank-side cathode 12, a wiring 14, and a first outlet 23a.

[0050] The first supply tank side cathode 12 is an electrode paired with the electrolytic cell side anode 11 and used in the electrolysis of the second aqueous solution L2. As described above, a first anion exchange membrane 30a is disposed between the first supply tank side cathode 12 and the electrolytic cell side anode 11. That is, the electrolysis of the second aqueous solution L2 performed using the pair of the first supply tank side cathode 12 and the electrolytic cell side anode 11 is membrane electrolysis (first membrane electrolysis). The first membrane electrolysis of the second aqueous solution L2 performed using the pair of the first supply tank side cathode 12 and the electrolytic cell side anode 11 generates hydroxide ions, and the hydroxide ions are supplied from the second aqueous solution L2 to the first aqueous solution L1. Furthermore, hydrogen is generated by the first membrane electrolysis of the second aqueous solution L2 performed using the pair of the first supply tank side cathode 12 and the electrolytic cell side anode 11.

[0051] The first supply tank side cathode 12 has a plate-like shape, similar to the electrolytic tank side anode 11. That is, the first supply tank side cathode 12 is a cathode plate having a plate-like shape and arranged on the first supply tank 20a side. The plate-like shape includes a rectangular shape or an oblong shape. Hereinafter, the first supply tank side cathode 12 may also be referred to as the "first supply tank side cathode plate."

[0052] As an example, a case will be described in which the plate shape of the first supply tank side cathode 12 is rectangular, the same as that of the electrolytic cell side anode 11. As shown in FIG. 1 , the first supply tank side cathode 12 is arranged such that the shorter side of the rectangle is aligned with the vertical direction (z-axis direction). This arrangement can prevent bubbles generated by chemical reactions from adhering to both sides of the rectangular electrode. Furthermore, compared to when the longer side of the rectangle is aligned with the vertical direction (z-axis direction), when the shorter side is aligned with the vertical direction (z-axis direction), bubbles generated at the lower part (negative side of the z-axis) of the first supply tank side cathode 12 can be prevented from adhering to the upper part (positive side of the z-axis) of the first supply tank side cathode 12.

[0053] 2, the first supply tank side cathode 12 is arranged such that the longitudinal direction of the rectangle is along the horizontal direction (y-axis direction). The first supply tank side cathode 12 and the electrolytic cell side anode 11 are arranged such that the planes of the rectangles (y-z planes) face each other with a predetermined distance between them. The predetermined distance is a distance appropriate for electrolysis performed using a pair of the electrolytic cell side anode 11 and the first supply tank side cathode 12.

[0054] The electrolytic cell side anode 11 and the first supply cell side cathode 12 are each in close proximity to the first anion exchange membrane 30a. In this specification, "in close proximity" includes both a state in which the electrolytic cell side anode 11 and the first supply cell side cathode 12 are close to the first anion exchange membrane 30a with a predetermined gap therebetween, and a state in which the electrolytic cell side anode 11 and the first supply cell side cathode 12 are in contact with the first anion exchange membrane 30a.

[0055] The plane of the rectangular plate on the first anion exchange membrane 30a side of the electrolytic cell side anode 11 (the yz plane on the negative x-axis side) is designated as plane P1. The plane of the rectangular plate on the first anion exchange membrane 30a side of the first supply tank side cathode 12 (the yz plane on the positive x-axis side) is designated as plane P2. Planes P1 and P2 are arranged opposite each other with the first anion exchange membrane 30a interposed therebetween. This arrangement allows a uniform electric field to be generated between the electrolytic cell side anode 11 and the first supply tank side cathode 12.

[0056] The first supply tank side cathode 12 includes a first supply tank side cathode plate immersion portion 12a and a first supply tank side cathode plate protrusion portion 12b. The first supply tank side cathode 12 is inserted from the outside of the first supply tank 20a toward the inside. In FIG. 2 , as an example, the first supply tank side cathode 12, like the electrolytic cell side anode 11, is inserted from the side of the first supply tank 20a (the xz plane side on the negative side of the y-axis) toward the horizontal direction (y-axis direction). The first supply tank side cathode plate immersion portion 12a inserted into the first supply tank 20a is a portion of the first supply tank side cathode 12 that is positioned inside the first supply tank 20a and is entirely immersed in the second aqueous solution L2. In other words, the second aqueous solution L2 is stored in the first supply tank 20a so that the entire first supply tank side cathode plate immersion portion 12a is immersed. That is, the second aqueous solution L2 is stored in the first supply tank 20a so that the liquid level S2 of the second aqueous solution L2 exceeds the upper end (the end on the positive side of the z-axis) of the cathode plate immersed portion 12a on the first supply tank side.

[0057] The first supply tank side cathode plate protrusion 12b is a portion of the first supply tank side cathode 12 that is arranged on the outside of the first supply tank 20a. The wiring 14 is a line through which current flows. The first supply tank side cathode plate protrusion 12b is electrically connected to the current control unit 40 via the wiring 14.

[0058] As the first supply tank side cathode 12, for example, a platinum iridium titanium electrode, a platinum electrode, a ruthenium titanium electrode, an iridium titanium oxide electrode, or the like may be used.

[0059] The first outlet 23a is an opening for discharging hydrogen gas generated by the first diaphragm electrolysis of the second aqueous solution L2 to the external space of the housing. The first outlet 23a may be, for example, a check valve. When a check valve is used as the first outlet 23a, hydrogen gas inside the first supply tank 20a is discharged to the external space, but the inflow of gases such as air from the external space can be suppressed. When the first diaphragm electrolysis of the second aqueous solution L2 is repeated, hydrogen gas accumulates inside the first supply tank 20a, and the internal pressure of the first supply tank 20a increases. This pressure opens the check valve, and the hydrogen gas is discharged to the external space of the first supply tank 20a.

[0060] (4. Second Supply Tank) The second supply tank 20b includes a second supply tank-side cathode 21, a wiring 22, and a second outlet 23b.

[0061] The second supply cell side cathode 21 is an electrode paired with the electrolytic cell side anode 11 and used in the electrolysis of the third aqueous solution L3. As shown in FIG. 1 , a second anion exchange membrane 30b is disposed between the electrolytic cell side anode 11 and the second supply cell side cathode 21. That is, the electrolysis of the third aqueous solution L3 performed using the pair of the electrolytic cell side anode 11 and the second supply cell side cathode 21 is membrane electrolysis (second membrane electrolysis). That is, the electrolytic cell side anode 11 is used in both the first membrane electrolysis and the second membrane electrolysis. Chloride ions are supplied from the third aqueous solution L3 to the first aqueous solution L1 by the second membrane electrolysis of the third aqueous solution L3 performed using the pair of the electrolytic cell side anode 11 and the second supply cell side cathode 21. Furthermore, hydrogen is produced by the second membrane electrolysis of the third aqueous solution L3 performed using the pair of the electrolytic cell side anode 11 and the second supply cell side cathode 21.

[0062] The second supply tank side cathode 21 has a plate-like shape, similar to the electrolytic tank side anode 11 and the first supply tank side cathode 12. That is, the second supply tank side cathode 21 is a cathode plate having a plate-like shape and arranged on the second supply tank 20b side. The plate-like shape includes a rectangular shape or an oblong shape. Hereinafter, the second supply tank side cathode 21 may also be referred to as the "second supply tank side cathode plate."

[0063] As an example, a case will be described in which the second supply tank side cathode 21 also has a rectangular plate shape, similar to the electrolytic tank side anode 11 and the first supply tank side cathode 12. As shown in Fig. 1, the second supply tank side cathode 21 is disposed so that the shorter side of the rectangle is aligned along the vertical direction (z-axis direction). Also, as shown in Fig. 2, the second supply tank side cathode 21 is disposed so that the longer side of the rectangle is aligned along the horizontal direction (y-axis direction).

[0064] The electrolytic cell side anode 11 and the second supply cell side cathode 21 are each close to the second anion exchange membrane 30b. In this specification, "close to" includes both a state in which the electrolytic cell side anode 11 and the second supply cell side cathode 21 are close to the second anion exchange membrane 30b with a predetermined gap therebetween, and a state in which the electrolytic cell side anode 11 and the second supply cell side cathode 21 are in contact with the second anion exchange membrane 30b.

[0065] The rectangular plane (yz plane on the positive x-axis side) on the second anion exchange membrane 30b side of the plate-shaped electrolytic cell side anode 11 is designated as plane P3. The rectangular plane (yz plane on the negative x-axis side) on the second anion exchange membrane 30b side of the plate-shaped second supply tank side cathode 21 is designated as plane P4. Planes P3 and P4 are arranged opposite each other with the second anion exchange membrane 30b interposed therebetween. This arrangement allows a uniform electric field to be generated between the electrolytic cell side anode 11 and the second supply tank side cathode 21.

[0066] The second supply tank side cathode 21 includes a second supply tank side cathode plate immersion portion 21a and a second supply tank side cathode plate protrusion portion 21b. The second supply tank side cathode 21 is inserted from the outside toward the inside of the second supply tank 20b. In FIG. 2 , as an example, the second supply tank side cathode 21 is inserted from the side of the second supply tank 20b (the xz plane side on the negative side of the y-axis) toward the horizontal direction (y-axis direction). The second supply tank side cathode plate immersion portion 21a inserted into the second supply tank 20b is a portion of the second supply tank side cathode 21 that is positioned inside the second supply tank 20b and is entirely immersed in the third aqueous solution L3. In other words, the third aqueous solution L3 is stored in the second supply tank 20b so that the entire second supply tank side cathode plate immersion portion 21a is immersed. That is, the third aqueous solution L3 is stored in the second supply tank 20b so that the liquid level S3 of the third aqueous solution L3 exceeds the upper end (the end on the positive side of the z-axis) of the second supply tank side cathode plate immersion portion 21a.

[0067] 2, the second supply tank side cathode plate protrusion 21b is a portion of the second supply tank side cathode 21 that is disposed on the outside of the second supply tank 20b. The wiring 22 is a line through which current flows. The second supply tank side cathode plate protrusion 21b is electrically connected to the current control unit 40 via the wiring 22.

[0068] As the second supply tank side cathode 21, for example, a platinum iridium titanium electrode, a platinum electrode, a ruthenium titanium electrode, an iridium titanium oxide electrode, or the like may be used.

[0069] The second outlet 23b is an opening for discharging hydrogen gas generated by the second diaphragm electrolysis of the third aqueous solution L3 to the external space of the housing. The second outlet 23b may be, for example, a check valve. When a check valve is used as the second outlet 23b, hydrogen gas inside the second supply tank 20b is discharged to the external space, but the inflow of gases such as air from the external space can be suppressed. When the second diaphragm electrolysis of the third aqueous solution L3 is repeated, hydrogen gas accumulates inside the second supply tank 20b, and the internal pressure of the second supply tank 20b increases. This pressure opens the check valve, and the hydrogen gas is discharged to the external space of the second supply tank 20b.

[0070] (5. Water Level Detector and Water Supply Unit) As shown in FIG. 1 , the space purification device 1 may further include a water level detector 18 and a water supply unit 19. The water level detector 18 detects the position of the liquid level S1 in the first aqueous solution L1. The water level detector 18 is, for example, a water level sensor. The water level detector 18 is disposed at least above (on the positive z-axis side) the upper end (on the positive z-axis side) of the electrolytic cell-side anode plate immersed portion 11a.

[0071] The water supply unit 19 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 supply unit 19 supplies water to the electrolytic cell 10 so that the water level in the electrolytic cell 10 does not fall below the upper end (the portion on the positive side of the z-axis) of the electrolytic cell-side anode plate immersion portion 11a. The water supply unit 19 may be, for example, a Peltier element that can cool and condense moisture contained in the air into droplets, or a water tank that can store water. The water supply unit 19 may be located in any position that allows it to supply water to the electrolytic cell 10, and may be located above the electrolytic cell 10 or above the second supply tank 20b as shown in FIG. 1.

[0072] When the space purification device 1 includes the water level detector 18 and the water supplier 19, the electrolytic cell-side anode plate immersed portion 11a can be kept immersed in the first aqueous solution L1, thereby suppressing exposure of the electrolytic cell-side anode plate immersed portion 11a to air due to a decrease in the first aqueous solution L1, and maintaining the electrolysis efficiency of the first diaphragm-equipped electrolysis.

[0073] 1 and 2, the space purification device 1 according to this embodiment includes a first diaphragm electrolysis unit E1 and a second diaphragm electrolysis unit E2. The current control unit 40 controls the first current flowing through the first diaphragm electrolysis unit E1 and the second current flowing through the second diaphragm electrolysis unit E2, thereby controlling the chemical reactions occurring in the first diaphragm electrolysis unit E1 and the second diaphragm electrolysis unit E2.

[0074] The first membrane-with-diaphragm electrolysis unit E1 is provided across the electrolytic cell 10 and the first supply cell 20a. The first membrane-with-diaphragm electrolysis unit E1 performs first membrane-with-diaphragm electrolysis via the first anion exchange membrane 30a by passing a first current between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12. More specifically, the first membrane-with-diaphragm electrolysis unit E1 performs membrane-with-diaphragm electrolysis of the first aqueous solution L1 to produce hypochlorous acid and membrane-with-diaphragm electrolysis of the second aqueous solution L2 to produce hydroxide ions and hydrogen by passing a first current between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12. In other words, the first membrane-with-diaphragm electrolysis unit E1 includes the electrolytic cell-side anode 11, the first supply cell-side cathode 12, and the first anion exchange membrane 30a.

[0075] The second membrane-with-diaphragm electrolysis unit E2 is provided across the electrolytic cell 10 and the second supply cell 20b. A second current is passed between the electrolytic cell-side anode 11 and the second supply cell-side cathode 21 to perform membrane-with-diaphragm electrolysis via the second anion exchange membrane 30b. More specifically, the second membrane-with-diaphragm electrolysis unit E2 generates hydrogen by passing a second current between the electrolytic cell-side anode 11 and the second supply cell-side cathode 21. In other words, the second membrane-with-diaphragm electrolysis unit E2 includes the electrolytic cell-side anode 11, the second supply cell-side cathode 21, and the second anion exchange membrane 30b.

[0076] 3 and 4, the chemical reactions occurring in the first diaphragm electrolysis unit E1 provided between the electrolytic cell 10 and the first supply cell 20a and the second diaphragm electrolysis unit E2 provided between the electrolytic cell 10 and the second supply cell 20b will be described in detail. Figures 3 and 4 are diagrams showing the chemical reaction formulas occurring in the first diaphragm electrolysis unit E1 and the second diaphragm electrolysis unit E2, which are constituted by the respective cell tanks of the space purification device 1. The following description will be given for a case in which the first aqueous solution L1 containing chloride ions is a sodium chloride aqueous solution, the second aqueous solution L2 containing hydroxide ions is a sodium hydroxide aqueous solution, and the third aqueous solution L3 containing chloride ions is a hydrochloric acid aqueous solution.

[0077] [First Diaphragm Electrolysis Unit E1 (Electrolytic Cell 10 and First Supply Cell 20a)] Sodium chloride (NaCl) contained in the sodium chloride aqueous solution, which is the first aqueous solution L1, is ＋ and Cl － In addition, sodium hydroxide (NaOH) contained in the sodium hydroxide aqueous solution, which is the second aqueous solution L2, is ionized into Na ＋ and OH － When a predetermined voltage is applied to the first membrane electrolysis section E1, a current flows, electrons move, and the following chemical reaction shown in FIG.

[0078] Reaction formula (a): Equation by which chlorine is generated from chloride ions at the electrolytic cell-side anode 11. Reaction formula (b): Equation by which hydrogen and hydroxide ions are generated from water at the first supply cell-side cathode 12. Reaction formula (c): Equation by which water and oxygen are generated from hydroxide ions at the electrolytic cell-side anode 11. Reaction formula (d): Equation by which hydrochloric acid and hypochlorous acid are generated from chlorine and water in the first aqueous solution L1. Reaction formula (e): Equation of the hypochlorous acid generation reaction at the electrolytic cell-side anode 11 (reaction formula (a) + reaction formula (d)). Reaction formula (f): Equation by which electrons in the first aqueous solution L1 are consumed and chloride ions are passed through the second anion exchange membrane 30b to supply chloride ions to the electrolytic cell 10. A voltage is applied to the first diaphragm electrolysis section E1, a current flows, and the first aqueous solution L1 stored in the electrolytic cell 10 converts electrons (e －) When one of the ions is lost, chloride ions Cl 1 are transferred from the third aqueous solution L3 stored in the second supply tank 20b through the second anion exchange membrane 30b to the first aqueous solution L1 in the electrolytic cell 10. － is supplied.

[0079] Meanwhile, the reaction formula (c) of the first diaphragm electrolysis proceeds, and the first aqueous solution L1 stored in the electrolytic cell 10 converts into hydroxide ions (OH － ) is consumed, hydroxide ions OH permeate from the second aqueous solution L2 stored in the first supply tank 20a through the first anion exchange membrane 30a and are added to the first aqueous solution L1 in the electrolytic cell 10. － At this time, the hydroxide ions OH － is produced according to reaction formula (b).

[0080] Here, the proportion of current used in the hypochlorous acid generation reaction of reaction formula (e) is represented by "x," and the proportion of current used in the oxygen generation reaction of reaction formula (c) is represented by "1-x." Furthermore, the proportion of current used in reaction formula (b) of the first diaphragm electrolysis is represented by "y," and the proportion of current used in reaction formula (f) of the second diaphragm electrolysis is represented by "1-y." Applying the above x and y to reaction formula (b) + (c) + (e) + (f) results in the following reaction formula (g) shown in FIG. 3 .

[0081] Reaction formula (g): A formula derived from reaction formulas (b) + (c) + (e) + (f) When membrane electrolysis is performed in the first membrane electrolysis unit E1, chloride ions in the electrolytic cell 10 are consumed and therefore reduced. However, in the space purification device 1 according to this embodiment, chloride ions are supplied from the third aqueous solution L3 stored in the second supply tank 20b to the first aqueous solution L1 stored in the electrolytic cell 10. Meanwhile, when membrane electrolysis is performed in the first membrane electrolysis unit E1, hydroxide ions in the electrolytic cell 10 are also consumed and therefore reduced. However, in the space purification device 1 according to this embodiment, hydroxide ions are supplied from the second aqueous solution L2 stored in the first supply tank 20a to the first aqueous solution L1 stored in the electrolytic cell 10.

[0082] Here, the amount of chloride ions (Cl ) consumed by the first diaphragm electrolysis is transferred from the third aqueous solution L3 stored in the second supply tank 20b to the first aqueous solution L1 stored in the electrolytic tank 10. － ) is supplied, and Cl is added to the electrolytic cell 10. － The conditions under which does not appear to increase or decrease are as follows, as shown in Figure 4. In this reaction, hypochlorous acid (HClO) volatilizes as a gas, so it is not included in the following formula.

[0083] Reaction formula (h): Cl － When reaction formula (h) is transformed, reaction formula (i) shown in FIG. 4 is obtained.

[0084] Reaction formula (i): Modification of reaction formula (h) Substituting y in reaction formula (i) into the above reaction formula (g) gives reaction formula (j) shown in FIG.

[0085] Reaction formula (j): Reaction formula (g) + (i) Transforming reaction formula (j) gives the following reaction formula (k).

[0086] Reaction formula (k): Modification of reaction formula (j) From reaction formula (k) shown in FIG. 4, for example, when two electrons flow to the first membrane electrolysis unit E1, one hypochlorous acid (HClO) is generated. For example, when four electrons flow to the first membrane electrolysis unit E1, one oxygen (O ２ For example, when two electrons flow into the first membrane electrolysis section E1, one hydrogen (H ２ ) is generated.

[0087] In addition, since the acid dissociation constant of hypochlorous acid (HClO) is approximately 7.5, it is necessary to maintain the pH of the first aqueous solution L1 unchanged. In reaction formula (k) shown in FIG. 4, hydroxide ions and hydrogen ions, which are the cause of the change in pH, react to form water and disappear from the reaction formula. Therefore, the amount of chloride ions (Cl ) consumed by the first diaphragm electrolysis is transferred from the third aqueous solution L3 stored in the second supply tank 20b to the first aqueous solution L1 stored in the electrolytic cell 10. － ) is supplied, and Cl is added to the electrolytic cell 10. － When the condition is such that there is no apparent increase or decrease in pH, the increase or decrease in pH can also be suppressed.

[0088] As described above, when the number of electrons flowing in the first diaphragm electrolysis unit E1 changes, that is, when the ratio of the current flowing in the first diaphragm electrolysis unit E1 to the current flowing in the second diaphragm electrolysis unit E2 changes, the supply amount of chloride ions supplied from the second supply tank 20b to the electrolytic cell 10 changes. For example, when the ratio of the current used in the first diaphragm electrolysis is changed from the current used in the second diaphragm electrolysis unit E2 to the current used in the second diaphragm electrolysis unit E2, the supply amount of chloride ions (Cl － ) is supplied to the electrolytic cell 10, and Cl － is greater than the current rate under the condition that there is no apparent increase or decrease (reaction formula (l) shown in FIG. 4), the Cl supplied from the second supply tank 20b to the electrolytic tank 10 － The supply amount of Cl in the electrolytic cell 10 decreases. － decreases.

[0089] Cl in the electrolytic cell 10 － When the electrolysis efficiency of the first membrane electrolysis is reduced, the Cl in the electrolytic cell 10 gradually decreases. － increases, and Cl － reaches a level that does not appear to increase or decrease.

[0090] On the other hand, the proportion of the current used in the first diaphragm electrolysis is such that chloride ions (Cl － ) is supplied to the electrolytic cell 10, and Cl － When the current ratio is smaller than the condition where there is no apparent increase or decrease (reaction formula (m) shown in FIG. 4), the Cl supplied from the second supply tank 20b to the electrolytic tank 10 － The supply amount of Cl in the electrolytic cell 10 increases. － increases.

[0091] Cl in the electrolytic cell 10 － When the electrolysis efficiency of the first membrane electrolysis is increased, the Cl in the electrolytic cell 10 gradually increases. － decreases, and Cl － reaches a level that does not appear to increase or decrease.

[0092] In addition, Cl in the electrolytic cell 10 － When the amount of Cl in the electrolytic cell 10 increases, the equilibrium of the reaction formula (d) shown in FIG. 3 shifts to the left, and the amount of chlorine generated increases.－ By adjusting the current flowing through the first membrane electrolysis section E1 and the current flowing through the second membrane electrolysis section E2 so that the apparent increase or decrease in the current does not occur, hypochlorous acid can be produced while suppressing the generation of chlorine.

[0093] [Second membrane-equipped electrolysis section E2 (electrolytic cell 10 and second supply cell 20b)] The reaction in the second supply cell 20b will be described. The only electrode arranged in the second supply cell 20b is the second supply cell-side cathode 21. When a predetermined voltage is applied to the second membrane-equipped electrolysis section E2, a current flows, electrons move, and the following chemical reaction shown in Figure 4 occurs.

[0094] Reaction formula (n): A formula for generating hydrogen and hydroxide ions from water at the second supply tank-side cathode 21. Reaction formula (o): A formula for obtaining electrons by consuming (supplying) chloride ions that permeate from the second supply tank 20b through the second anion exchange membrane 30b. When a voltage is applied to the second membrane-type electrolysis unit E2 and a current flows, chloride ions (Cl ) contained in the third aqueous solution L3 stored in the second supply tank 20b are consumed (supplied). － ) permeates the second anion exchange membrane 30b and is supplied to the first aqueous solution L1, and the third aqueous solution L3 contains electrons (e － ) You get 1.

[0095] The above is a detailed description of the chemical reaction occurring in the first membrane electrolysis section E1 provided between the electrolytic cell 10 and the first supply cell 20a, and the chemical reaction occurring in the second membrane electrolysis section E2 provided between the electrolytic cell 10 and the second supply cell 20b.

[0096] (8. Current Control Unit) The current control unit 40 controls the chemical reaction. More specifically, the current control unit 40 controls the second current so as to replenish the chloride ions contained in the first aqueous solution L1 that have been reduced by the first diaphragm electrolysis in the first diaphragm electrolysis unit E1. By controlling the second current, the current control unit 40 causes chloride ions contained in the third aqueous solution L3 to permeate through the second anion exchange membrane 30b and supply them to the first aqueous solution L1. Details will be described below with reference to FIG. 5.

[0097] The functions of the current control unit 40 can be realized by a known controller configuration (such as a hardware circuit or a combination of a computer and software).

[0098] 5 is a block diagram showing the current control unit 40 according to embodiment 1. As shown in FIG. 5, the current control unit 40 includes a voltage acquisition unit 41, a calculation unit 42, and an estimation unit 43.

[0099] The voltage acquisition unit 41 acquires the voltage between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12. The voltage acquisition unit 41 is, for example, a voltmeter. The calculation unit 42 calculates the conductivity of the first aqueous solution L1 based on the voltage acquired by the voltage acquisition unit 41. The estimation unit 43 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 42.

[0100] The current control unit 40 controls the first current passed through the first membrane electrolysis unit E1 and the second current passed through the second membrane electrolysis unit E2 shown in Figures 1 and 2 so as to maintain the chloride ion concentration in the first aqueous solution L1 at a predetermined concentration. Three examples of current control by the current control unit 40 will be described below.

[0101] [1. When the first current and the second current are caused to flow simultaneously] When the current control unit 40 causes the first current and the second current to flow simultaneously, it performs the following controls (1) to (3).

[0102] (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is lower than a predetermined concentration: the current ratio between the first current and the second current is changed so as to increase the amount of chloride ions that permeate from the third aqueous solution L3 through the second anion exchange membrane 30b and are supplied to the first aqueous solution L1. More specifically, the current ratio of the first current is decreased and the current ratio of the second current is increased.

[0103] (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is higher than a predetermined concentration: the current ratio between the first current and the second current is changed so as to reduce the amount of chloride ions that permeate from the third aqueous solution L3 through the second anion exchange membrane 30b 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 decreased.

[0104] (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is a predetermined concentration: the current ratio between the first current and the second current is not changed.

[0105] [2. When the first current flows at a predetermined value and the second current is controlled at the same time] When the current control unit 40 flows the first current at a predetermined value and controls the second current at the same time, the current control unit 40 performs the following controls (1) to (3).

[0106] (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is lower than a predetermined concentration: A second current is passed so as to increase the amount of chloride ions that pass through the second anion exchange membrane 30b from the third aqueous solution L3 and are supplied to the first aqueous solution L1.

[0107] (2) If the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is higher than a predetermined concentration: The second current is stopped so that the supply of chloride ions from the third aqueous solution L3 to the first aqueous solution L1 is stopped.

[0108] (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is a predetermined concentration: the first current and the second current are not changed.

[0109] [3. When the First Current or the Second Current is Passed] When the current control unit 40 passes the first current or the second current, it performs the following controls (1) to (3).

[0110] (1) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is lower than a predetermined concentration: The first current is stopped and the second current is simultaneously passed so as to increase the amount of chloride ions that pass through the second anion exchange membrane 30b from the third aqueous solution L3 and are supplied to the first aqueous solution L1.

[0111] (2) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is higher than a predetermined concentration: The second current is stopped and the first current is simultaneously passed so as to stop the supply of chloride ions from the third aqueous solution L3 to the first aqueous solution L1.

[0112] (3) When the chloride ion concentration of the first aqueous solution L1 estimated by the estimation unit 43 is a predetermined concentration: the first current and the second current are not changed.

[0113] As described above, the current control unit 40 controls the first current and the second current, so that the required amount of chloride ions can be supplied to the first aqueous solution L1 in the electrolytic cell 10, and the chloride ion concentration in the first aqueous solution L1 can be maintained at a predetermined concentration.

[0114] In the above-mentioned "1. When the first current and the second current are passed simultaneously," the current ratio between the first current and the second current is changed when there is an increase or decrease in the chloride ion concentration of the first aqueous solution L1. Because the first current and the second 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.

[0115] In "2. When the first current is passed at a predetermined value while the second current is controlled simultaneously," the second current is mainly passed or stopped when the chloride ion concentration of the first aqueous solution L1 increases or decreases. In "3. When the first current or the second current is passed," one of the first current and the second current is passed and the other is stopped when the chloride ion concentration of the first aqueous solution L1 increases or decreases. Therefore, the chloride ion concentration of the first aqueous solution L1 can be maintained at a predetermined concentration. In the above cases 2 and 3, it is only necessary to control either the first current or the second current, making current control easy.

[0116] As described above, in this embodiment, the chloride ions consumed by the first aqueous solution L1 can be appropriately supplied from the third aqueous solution L3, thereby providing the space purification device 1 that can stably generate a desired amount of hypochlorous acid gas. Therefore, it is 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, such as one year, without supplying an aqueous solution containing chloride ions from the outside.

[0117] It is also possible to provide a plurality of current control units 40 and control the first current and the second current separately.

[0118] 2, the inlet 15 and the outlet 17 are respectively arranged on the lower right side (negative side of the y-axis and positive side of the x-axis) and the upper left side (positive side of the y-axis and negative side of the x-axis) when the electrolytic cell 10 is viewed from above, but the arrangement is not limited to this. For example, the positions of the inlet 15 and the outlet 17 may be reversed, the inlet 15 and the outlet 17 may be at the same position on the x-axis, or the inlet 15 and the outlet 17 may be at the same position on the y-axis.

[0119] However, it is preferable to arrange the inlet 15 and the outlet 17 so that they are as far apart as possible on the xy plane. By arranging them in this way, the time during which the inflowing air and hypochlorous acid are mixed in the mixing space 16 is extended, so that a larger amount of hypochlorous acid can be contained in the mixed air.

[0120] Next, we will explain the case where the plane P1 (yz plane on the negative side of the x-axis) of the first anion exchange membrane 30a side of the rectangular plate of the electrolytic cell side anode 11 and the plane P2 (yz plane on the positive side of the x-axis) of the first supply cell side cathode 12 do not face each other.

[0121] For example, if the plane of each rectangle is arranged parallel to the xy plane, a non-uniform electric field may be generated between the electrolytic cell side anode 11 and the first supply cell side cathode 12. If a non-uniform electric field is generated between the electrolytic cell side anode 11 and the first supply cell side cathode 12, the current distribution between the electrolytic cell side anode 11 and the first supply cell side cathode 12 will also be non-uniform.

[0122] When the current distribution between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12 becomes uneven, regions of high and low current density are generated. In the high current density regions, deterioration of the catalytic layer on the surfaces of the electrolytic cell-side anode 11 and the first supply cell-side cathode 12 (hereinafter also referred to as each electrode plate) is likely to progress, while in the low current density regions, deterioration of the catalytic layer on the surface of each electrode plate is unlikely to progress. In other words, when an uneven electric field is generated between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12, the current distribution becomes uneven, and regions of different current densities may exist simultaneously on the same electrode plate. Therefore, uneven deterioration of the catalytic layer due to use of each electrode plate may occur.

[0123] If the degree of deterioration of the catalyst layer on the surface of each electrode plate differs, repeated electrolysis may result in the simultaneous presence of regions on each electrode plate that can be used as an electrode and regions that have deteriorated to the point where they can no longer be used. When electrolysis is performed using electrode plates that include regions that cannot be used as electrodes, there is a risk that the electrolysis efficiency may be reduced.

[0124] In contrast, in the spatial purification device 1 according to this embodiment, the planes P1 and P2 are arranged opposite each other with the first anion exchange membrane 30a interposed therebetween. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side anode 11 and the first supply cell-side cathode 12, resulting in a uniform current distribution between the two electrodes. Therefore, deterioration of the catalyst layer on the surface of each electrode plate occurs uniformly, and uneven deterioration of the catalyst layer on the surface of each electrode plate due to an uneven electric field can be suppressed even when electrolysis is performed repeatedly. This suppresses a decrease in electrolysis efficiency.

[0125] Similarly, when the current distribution between the electrolytic cell-side anode 11 and the second supply cell-side cathode 21 becomes uneven, regions of high and low current density are generated. The high current density regions are more susceptible to deterioration of the catalytic layer on the surfaces of the electrolytic cell-side anode 11 and the second supply cell-side cathode 21 (hereinafter also referred to as each electrode plate), while the low current density regions are less susceptible to deterioration of the catalytic layer on the surfaces of each electrode plate. That is, when an uneven electric field is generated between the electrolytic cell-side anode 11 and the second supply cell-side cathode 21, the current distribution becomes uneven, and regions of different current densities may exist simultaneously on the same electrode plate. Therefore, uneven deterioration of the catalytic layer may occur due to the use of each electrode plate. If the degree of deterioration of the catalytic layer on the surface of each electrode plate differs, repeated electrolysis may result in the simultaneous existence of regions on each electrode plate that can be used as an electrode and regions that have deteriorated to the point where they become unusable. When electrolysis is performed using electrode plates that include regions that cannot be used as electrodes, the electrolysis efficiency may be reduced.

[0126] In contrast, in the spatial purification device 1 according to this embodiment, the planes P3 and P4 are arranged opposite each other with the second anion exchange membrane 30b interposed therebetween. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side anode 11 and the second supply cell-side cathode 21, resulting in a uniform current distribution between the two electrodes. Therefore, deterioration of the catalyst layer on the surface of each electrode plate occurs uniformly, and uneven deterioration of the catalyst layer on the surface of each electrode plate due to an uneven electric field can be suppressed, even when electrolysis is performed repeatedly. This suppresses a decrease in electrolysis efficiency.

[0127] (10. Summary of the Present Disclosure) An overview of one aspect of the present disclosure is as follows.

[0128] (Item 1) An electrolytic cell (10) for storing a first aqueous solution (L1) containing chloride ions; a first supply tank (20a) for storing a second aqueous solution (L2) containing hydroxide ions and supplying the hydroxide ions to the first aqueous solution (L1); a second supply tank (20b) for storing a third aqueous solution (L3) containing the chloride ions at a higher concentration than the first aqueous solution (L1) and supplying the chloride ions to the first aqueous solution (L1); an electrolytic cell-side anode (11) provided in the electrolytic cell (10); a first supply tank-side cathode (12) provided in the first supply tank (20a); and a second supply tank-side cathode (21) provided in the second supply tank (20b). a first anion exchange membrane (30a) that connects the electrolytic cell (10) and the first supply cell (20a) in a manner that allows anions to pass therethrough based on a voltage applied between the electrolytic cell-side anode (11) and the first supply cell-side cathode (12); and a second anion exchange membrane (30b) that connects the electrolytic cell (10) and the second supply cell (20b) in a manner that allows anions to pass therethrough based on a voltage applied between the electrolytic cell-side anode (11) and the second supply cell-side cathode (21). a first membrane electrolysis section (E1) provided between the electrolytic cell (10) and the first supply cell (20a) and configured to perform first membrane electrolysis of the first aqueous solution (L1) and the second aqueous solution (L2) via the first anion exchange membrane (30a) by passing a first current between the electrolytic cell-side anode (11) and the first supply cell-side cathode (12) to produce hypochlorous acid in the electrolytic cell (10); and a second membrane electrolysis section (E2) provided between the electrolytic cell (10) and the second supply cell (20b) and configured to perform second membrane electrolysis via the second anion exchange membrane (30b) by passing a second current between the electrolytic cell-side anode (11) and the second supply cell-side cathode (21). a current control unit (40) that controls the second current so as to replenish the chloride ions contained in the first aqueous solution (L1) that have been reduced by the first diaphragm electrolysis, thereby causing the chloride ions contained in the third aqueous solution (L3) to permeate through the second anion exchange membrane (30b) and supply them to the first aqueous solution (L1).

[0129] According to this configuration, chloride ions consumed by the first aqueous solution (L1) can be appropriately supplied from the third aqueous solution (L3), thereby providing an air purification device (1) capable of stably generating a desired amount of hypochlorous acid gas. Therefore, a desired amount of hypochlorous acid gas can be stably generated over a long period of time, such as one year, without supplying an aqueous solution containing chloride ions from the outside.

[0130] (Item 2) The space purification device (1) according to Item 1, wherein the current control unit (40) maintains the chloride ion concentration of the first aqueous solution (L1) at a predetermined concentration by flowing the first current and the second current at a predetermined ratio.

[0131] According to this configuration, the chloride ion concentration in the first aqueous solution (L1) is further maintained at a predetermined concentration, so that a desired amount of hypochlorous acid gas can be stably generated.

[0132] (Item 3) The current control unit (40) comprises: a voltage acquisition unit (41) that acquires a voltage between the electrolytic cell-side anode (11) and the first supply cell-side cathode (12); a calculation unit (42) that calculates the conductivity of the first aqueous solution (L1) based on the voltage acquired by the voltage acquisition unit (41); and an estimation unit (43) that estimates the concentration of the first aqueous solution (L1) based on the conductivity calculated by the calculation unit (42), wherein the current control unit (40) simultaneously applies the first current and the second current, and when the chloride ion concentration of the first aqueous solution (L1) is lower than a predetermined concentration, changes the current ratio between the first current and the second current so as to increase the amount of chloride ions that permeate the second anion exchange membrane (30b) from the third aqueous solution (L3) and are supplied to the first aqueous solution (L1), Item 1. The space purification device (1) according to Item 1, wherein, when the chloride ion concentration in the first aqueous solution (L1) is higher than the predetermined concentration, the current ratio between the first current and the second current is changed so as to reduce the amount of chloride ions that permeate from the third aqueous solution (L3) through the second anion exchange membrane (30b) and are supplied to the first aqueous solution (L1).

[0133] According to this configuration, when the first current and the second current are passed simultaneously, the current ratio between the first current and the second current is controlled, so that the chloride ion concentration in the first aqueous solution (L1) is maintained at a predetermined concentration, and the desired amount of hypochlorous acid gas can be stably generated.

[0134] (Item 4) The space purification device (1) according to Item 3, wherein the current control unit (40) does not change the current ratio between the first current and the second current when the chloride ion concentration of the first aqueous solution (L1) is the predetermined concentration.

[0135] Furthermore, with this configuration, the current ratio between the first current and the second current is not changed, so that a desired amount of hypochlorous acid gas can be stably generated with simple control.

[0136] (Item 5) The current control unit (40) comprises: a voltage acquisition unit (41) that acquires a voltage between the electrolytic cell-side anode (11) and the first supply cell-side cathode (12); a calculation unit (42) that calculates the conductivity of the first aqueous solution (L1) based on the voltage acquired by the voltage acquisition unit (41); and an estimation unit (43) that estimates the concentration of the first aqueous solution (L1) based on the conductivity calculated by the calculation unit (42), wherein the current control unit (40) controls the second current while causing the first current to flow at a predetermined value, and controls the second current by: when the chloride ion concentration of the first aqueous solution (L1) is lower than a predetermined concentration, causing the second current to flow so as to increase the amount of chloride ions that permeate the second anion exchange membrane (30b) from the third aqueous solution (L3) and are supplied to the first aqueous solution (L1); 2. The space purification device (1) according to item 1, wherein, when the chloride ion concentration in the first aqueous solution (L1) is higher than the predetermined concentration, the second current is stopped so that the supply of the chloride ions from the third aqueous solution (L3) to the first aqueous solution (L1) is stopped.

[0137] According to this configuration, when the first current is passed at a predetermined value and the second current is passed at the same time, only the second current is controlled. Therefore, the chloride ion concentration of the first aqueous solution (L1) can be maintained at a predetermined concentration through simple control, and the desired amount of hypochlorous acid gas can be stably generated.

[0138] (Item 6) The current control unit (40) comprises: a voltage acquisition unit (41) that acquires a voltage between the electrolytic cell side anode (11) and the first supply cell side cathode (12); a calculation unit (42) that calculates the conductivity of the first aqueous solution (L1) based on the voltage acquired by the voltage acquisition unit (41); and an estimation unit (42) that estimates the concentration of the first aqueous solution (L1) based on the conductivity calculated by the calculation unit (42), and the current control unit (40) stops the first current and simultaneously starts the second current so that the amount of chloride ions that permeate the third aqueous solution (L3) through the second anion exchange membrane (30b) and are supplied to the first aqueous solution (L1) increases when the chloride ion concentration of the first aqueous solution (L1) is lower than a predetermined concentration, 2. The space purification device (1) according to Item 1, wherein, when the chloride ion concentration in the first aqueous solution (L1) is higher than a predetermined concentration, the second current is stopped and the first current is simultaneously passed so as to stop the supply of the chloride ions from the third aqueous solution (L3) to the first aqueous solution (L1).

[0139] According to this configuration, the first current is stopped and the second current is allowed to flow at the same time, or the second current is stopped and the first current is allowed to flow at the same time, so that the chloride ion concentration in the first aqueous solution (L1) is maintained at a predetermined concentration, and the desired amount of hypochlorous acid gas can be stably generated.

[0140] (Item 7) The space purification device (1) according to Item 1, wherein when the first aqueous solution (L1) is a sodium chloride aqueous solution or a potassium chloride aqueous solution and the third aqueous solution (L3) is a hydrochloric acid aqueous solution, the third aqueous solution (L3) contains sodium chloride or potassium chloride so that its molar concentration is the same as that of the sodium ions or potassium ions contained in the first aqueous solution (L1).

[0141] This configuration further prevents metal cations (sodium ions or potassium ions) contained in the first aqueous solution (L1) from permeating into the third aqueous solution (L3) through the second anion exchange membrane (30b), thereby preventing changes in pH due to the permeation of metal cations. In other words, it is possible to prevent unintended changes in pH of the first aqueous solution (L1).

[0142] (Item 8) The space purification device (1) according to Item 1, further comprising: a housing that stores the electrolytic cell (10), the first supply tank (20a), and the second supply tank (20b); an inlet (15) that is disposed within the housing above a liquid level (S1) of the first aqueous solution (L1) stored in the electrolytic cell (10), and through which air flows in from an external space of the housing; a mixing space (16) that mixes the volatilized hypochlorous acid with the air that has flowed in from the inlet (15); and an outlet (17) through which the mixed air flows out to the external space.

[0143] According to this configuration, air introduced into the inlet (15) from the space outside the space purification device (1) can be mixed with hypochlorous acid in the mixing space (16) and then released into the space outside through the outlet (17). This makes it possible to remove bacteria, fungi, viruses, odors, etc. contained in the air in the space outside the space purification device (1).

[0144] The present disclosure has been described above based on the embodiments, but the present disclosure is not limited to the above embodiments, and it can be easily understood by those skilled in the art that various improvements and modifications are possible within the scope of the spirit of the present disclosure.

[0145] For example, in the space purification device 1 according to the first embodiment, the electrodes (electrolytic cell-side anode 11, first supply cell-side cathode 12, second supply cell-side cathode 21) are inserted from the side of each cell (the xz plane side on the negative side of the y-axis) toward the inside of each cell (electrolytic cell 10, first supply cell 20a, second supply cell 20b) in the horizontal direction (y-axis direction), but the present disclosure is not limited to this.

[0146] For example, each electrode may be inserted from the upper side of the top surface of each tank (positive side of the z-axis in FIG. 1 ) toward the inside of each tank (negative direction of the z-axis), or from the lower side of the bottom surface of each tank (negative side of the z-axis) toward the inside of each tank (positive direction of the z-axis).

[0147] Furthermore, in the space purification device 1 according to the first embodiment, the inlet 15, which is an opening for allowing air from the space outside the housing to flow in, is provided on the top surface of the electrolytic cell 10 (the x-y plane on the positive side of the z-axis in FIG. 1 ), but the present disclosure is not limited to this. For example, the inlet 15 may be provided on the bottom surface of the electrolytic cell 10 (the x-y plane on the negative side of the z-axis in FIG. 1 ), and air may be introduced by an air pump. This allows air to be supplied as bubbles from the inlet 15 into the first aqueous solution L1, allowing the air released from the outlet 17 to contain a larger amount of hypochlorous acid gas.

[0148] The air purifying device of this embodiment can stably generate the desired amount of hypochlorous acid gas for a long period of time without supplying an aqueous solution containing chloride ions from the outside, and is therefore useful as a device for purifying or sterilizing indoor spaces, etc.

[0149] 1. Space Purification Device 10. Electrolytic Cell 11. Electrolytic Cell-Side Anode 11a. Electrolytic Cell-Side Anode Plate Immersed Portion 11b. Electrolytic Cell-Side Anode Plate Protruding Portion 12. First Supply Cell-Side Cathode 12a. First Supply Cell-Side Cathode Plate Immersed Portion 12b. First Supply Cell-Side Cathode Plate Protruding Portion 13. Wiring 14. Wiring 15. Inlet 16. Mixing Space 17. Outlet 18. Water Level Detection Portion 19. Water Supply Portion 20a. First Supply Cell 20b. Second Supply Cell 21. Second Supply Cell-Side Cathode 21a. Second Supply Cell-Side Cathode Plate Immersed Portion 21b. Second Supply Cell-Side Cathode Plate Protruding Portion 22. Wiring 23a. First Discharge Port 23b. Second Discharge Port 30a. First Anion Exchange Membrane 30b. Second Anion Exchange Membrane 40. Current Control Portion 41. Voltage Acquisition Portion 42. Calculation Portion 43. Estimation Portion E1 First electrolysis section with diaphragm E2 Second electrolysis section with diaphragm L1 First aqueous solution L2 Second aqueous solution L3 Third aqueous solution P1 Plane P2 Plane P3 Plane P4 Plane S1 Liquid level S2 Liquid level S3 Liquid level

Claims

1. An electrolytic cell for storing a first aqueous solution containing chloride ions, a first supply cell for storing a second aqueous solution containing hydroxide ions and supplying the hydroxide ions to the first aqueous solution, a second supply cell for storing a third aqueous solution containing a higher concentration of chloride ions than the first aqueous solution and supplying the chloride ions to the first aqueous solution, an electrolytic cell-side anode provided in the electrolytic cell, a first supply cell-side cathode provided in the first supply cell, a second supply cell-side cathode provided in the second supply cell, a first anion exchange membrane connecting the electrolytic cell and the first supply cell to be permeable to anions based on a voltage applied between the electrolytic cell-side anode and the first supply cell-side cathode, and a second anion exchange membrane connecting the electrolytic cell and the second supply cell to be permeable to anions based on a voltage applied between the electrolytic cell-side anode and the second supply cell-side cathode. a first diaphragm electrolysis section provided between the electrolytic cell and the first supply cell, which performs first membrane electrolysis of the first aqueous solution and the second aqueous solution through the first anion exchange membrane by passing a first current between the electrolytic cell side anode and the first supply cell side cathode to produce hypochlorous acid in the electrolytic cell; a second diaphragm electrolysis section provided between the electrolytic cell and the second supply cell, which performs second membrane electrolysis through the second anion exchange membrane by passing a second current between the electrolytic cell side anode and the second supply cell side cathode; and a current control section which controls the second current so as to replenish the chloride ions contained in the first aqueous solution that have been reduced by the first diaphragm electrolysis, thereby causing the chloride ions contained in the third aqueous solution to permeate through the second anion exchange membrane and supply them to the first aqueous solution.

2. The spatial purification device according to claim 1, wherein the current control unit maintains the chloride ion concentration of the first aqueous solution at a predetermined concentration by flowing the first current and the second current at a predetermined ratio.

3. The space purification device according to claim 1, wherein the current control unit comprises: a voltage acquisition unit that acquires a voltage between the electrolytic cell side anode and the first supply cell side cathode; a calculation unit that calculates the conductivity of the first aqueous solution based on the voltage acquired by the voltage acquisition unit; and an estimation unit that estimates the concentration of the first aqueous solution based on the conductivity calculated by the calculation unit, wherein the current control unit simultaneously flows the first current and the second current, and when a chloride ion concentration of the first aqueous solution is lower than a predetermined concentration, changes the current ratio of the first current to the second current so as to increase the amount of the chloride ions that permeate the second anion exchange membrane from the third aqueous solution and are supplied to the first aqueous solution, and when a chloride ion concentration of the first aqueous solution is higher than the predetermined concentration, changes the current ratio of the first current to the second current so as to decrease the amount of the chloride ions that permeate the second anion exchange membrane from the third aqueous solution and are supplied to the first aqueous solution.

4. The spatial purification device according to claim 3, wherein the current control unit does not change the current ratio between the first current and the second current when the chloride ion concentration of the first aqueous solution is the specified concentration.

5. The space purification device according to claim 1, wherein the current control unit comprises: a voltage acquisition unit that acquires a voltage between the electrolytic cell side anode and the first supply cell side cathode; a calculation unit that calculates the conductivity of the first aqueous solution based on the voltage acquired by the voltage acquisition unit; and an estimation unit that estimates the concentration of the first aqueous solution based on the conductivity calculated by the calculation unit, and the current control unit controls the second current while flowing the first current at a predetermined value, and controls the second current by: when the chloride ion concentration of the first aqueous solution is lower than a predetermined concentration, flowing the second current so as to increase the amount of chloride ions that permeate through the second anion exchange membrane from the third aqueous solution and are supplied to the first aqueous solution; and when the chloride ion concentration of the first aqueous solution is higher than the predetermined concentration, stopping the second current so as to stop the supply of chloride ions from the third aqueous solution to the first aqueous solution.

6. The space purification device according to claim 1, wherein the current control unit comprises: a voltage acquisition unit that acquires a voltage between the electrolytic cell side anode and the first supply cell side cathode; a calculation unit that calculates the conductivity of the first aqueous solution based on the voltage acquired by the voltage acquisition unit; and an estimation unit that estimates the concentration of the first aqueous solution based on the conductivity calculated by the calculation unit; and wherein, when the chloride ion concentration of the first aqueous solution is lower than a predetermined concentration, the current control unit stops the first current and simultaneously flows the second current so as to increase the amount of chloride ions that permeate through the second anion exchange membrane from the third aqueous solution and are supplied to the first aqueous solution, and when the chloride ion concentration of the first aqueous solution is higher than a predetermined concentration, the current control unit stops the second current and simultaneously flows the first current so as to stop the supply of chloride ions from the third aqueous solution to the first aqueous solution.

7. The spatial purification device according to claim 1, wherein, when the first aqueous solution is a sodium chloride aqueous solution or a potassium chloride aqueous solution and the third aqueous solution is a hydrochloric acid aqueous solution, the third aqueous solution contains sodium chloride or potassium chloride so that its molar concentration is the same as that of the sodium ions or potassium ions contained in the first aqueous solution.

8. The space purification device of claim 1, further comprising: a housing that houses the electrolytic cell, the first supply tank, and the second supply tank; an inlet located within the housing above the liquid level of the first aqueous solution stored in the electrolytic cell, through which air flows in from an external space of the housing; a mixing space that mixes the volatilized hypochlorous acid with the air that has flowed in from the inlet; and an outlet through which the mixed air flows out to the external space.

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