Space purification device

Abstract

A space purification device (1) comprises a current control unit (40) that supplies chloride ions contained in a second aqueous solution (L2) stored in a supply tank (20) to a first aqueous solution (L1) through an anion exchange membrane (30) so as to compensate for chloride ions that are contained in the first aqueous solution (L1) and are reduced by membraneless electrolysis. The current control unit (40) supplies the chloride ions contained in the second aqueous solution (L2) to the first aqueous solution (L1) through the anion exchange membrane (30) by channeling a second electrical current. The current control unit (40) channels a first electrical current and the second electrical current at a prescribed current ratio, and performs control to change the current ratio in accordance with a prescribed operation time, such that the concentration of hypochlorous acid in the first aqueous solution (L1) is maintained at a prescribed concentration.

Description

Space Purification Device

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

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

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

[0004] However, when generating hypochlorous acid water by electrolysis of sodium chloride solution in an air purification device, sodium hydroxide, a strong alkaline substance, may be generated. When such an air purification device is miniaturized and installed at a designated installation site by a contractor, it is expected that the contractor may remove the air purification device after use, or the air purification device may tip over or fall during transportation after removal. In this case, there is a possibility that the generated sodium hydroxide, a strong alkaline substance, may leak outside the air purification device.

[0005] The present disclosure provides a space purification device that can stably supply hypochlorous acid by suppressing strong alkalinity after electrolysis of an aqueous solution stored in a supply tank, thereby improving safety.

[0006] The spatial purification device according to the present disclosure includes an electrolytic cell for storing a first aqueous solution containing chloride ions, a supply cell for storing a second 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 and an electrolytic cell-side cathode provided in the electrolytic cell, a supply cell-side cathode provided in the supply cell, an anion exchange membrane provided to connect the electrolytic cell and the supply cell and allowing anions to pass therethrough based on a voltage applied between the electrolytic cell-side anode and the supply cell-side cathode, and an anion exchange membrane provided in the electrolytic cell and allowing anions to pass therethrough based on a voltage applied between the electrolytic cell-side anode and the supply cell-side cathode. The electrolysis system includes a diaphragm-less electrolysis unit that generates hypochlorous acid by performing diaphragm-less electrolysis of a first aqueous solution by passing a first current between the electrolytic cell-side anode and the supply cell-side cathode, a diaphragm-containing electrolysis unit that is disposed between the electrolytic cell and the supply cell and performs diaphragm-containing electrolysis via an anion exchange membrane by passing a second current between the electrolytic cell-side anode and the supply cell-side cathode, and a current control unit that supplies chloride ions contained in a second aqueous solution stored in the supply cell through the anion exchange membrane to the first aqueous solution so as to replenish chloride ions contained in the first aqueous solution reduced by the diaphragm-less electrolysis. The current control unit passes the second current to pass chloride ions contained in the second aqueous solution through the anion exchange membrane to the first aqueous solution. The current control unit controls the first and second currents to flow at a predetermined current ratio and changes the current ratio according to a predetermined operating time so that the hypochlorous acid concentration in the first aqueous solution is maintained at a predetermined concentration.

[0007] The present disclosure makes it possible to provide a space purification device that can suppress strong alkalinity after electrolysis of an aqueous solution, thereby improving safety and enabling a stable supply of hypochlorous acid.

[0008] Fig. 1 is a perspective view showing a space purification device according to an embodiment. Fig. 2 is a partial front cross-sectional view showing the space purification device of Fig. 1. Fig. 3 is a list of reaction formulas occurring in the diaphragm-less electrolysis section. Fig. 4 is a reaction formula showing the ratio of current flowing in the diaphragm-less electrolysis section to the current flowing in the diaphragm-containing electrolysis section. Fig. 5 is a list of reaction formulas occurring in the diaphragm-containing electrolysis section. Fig. 6 is a graph showing the correlation between the amount of hypochlorous acid and chlorine generated and the current ratio. Fig. 7 is a block diagram showing a current control section according to an embodiment.

[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 the figures is for the convenience of explaining the positional relationships of the components. Unless otherwise specified, the positive direction of the z axis is vertically upward. The xy plane is a horizontal plane, which is common to all the figures.

[0011] 1 is a perspective view showing an outline of a space purification device 1 according to an embodiment. The space purification device 1 performs electrolysis on a first aqueous solution L1 containing chloride ions in an electrolytic cell 10 (described later) to generate and volatilize hypochlorous acid. The space purification device 1 removes bacteria, fungi, viruses, odors, and the like contained in the air in the external space of the space purification device 1 by discharging the volatilized hypochlorous acid into the external space of a housing B constituting the space purification device 1.

[0012] The space purification device 1 is installed indoors. The installation location of the space purification device 1 is preferably a location where air flow can occur. More specifically, the installation locations of the space purification device 1 include, for example, inside an air conditioner, which is an air conditioner, around an electric fan, around a circulator, around a ceiling fan, inside a humidifier, inside an air purifier, and on a desk.

[0013] The spatial purification device 1 includes a housing B, an electrolytic cell 10 , a supply cell 20 , an anion exchange membrane 30 , and a current control unit 40 .

[0014] The housing B houses the electrolytic cell 10, the supply cell 20, the anion exchange membrane 30, and the current control unit 40. That is, the space purification device 1 may be an integrated unit formed by the housing B. The shape of the housing B can be changed appropriately depending on the location where the space purification device 1 is installed, and may be, for example, a rectangular parallelepiped or cylindrical shape. The space purification device 1 has a small size that can be stored inside an air conditioner, for example, approximately 10 cm x 7 cm x 4 cm.

[0015] 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, an aqueous solution in which an electrically conductive electrolyte is dissolved, and specifically, a dilute chloride aqueous solution having a predetermined chloride ion concentration. More specifically, the first aqueous solution L1 is, for example, a dilute sodium chloride aqueous solution or a dilute potassium chloride aqueous solution.

[0016] The "predetermined chloride ion concentration" of the first aqueous solution L1 includes both a chloride ion concentration having a predetermined numerical range and a chloride ion concentration having a predetermined numerical value. More specifically, the chloride ion concentration of the first aqueous solution L1 may be, for example, 1 g / L to 50 g / L, or may be 10 g / L. In other words, the mass percent concentration of the dilute sodium chloride aqueous solution or the dilute potassium chloride aqueous solution may be, for example, 0.1% to 5%, or may be 5%. By setting the predetermined chloride ion concentration to this numerical range or numerical value, it is possible to generate hypochlorous acid necessary for space purification while simultaneously suppressing the generation of chlorine, which may be generated.

[0017] The supply tank 20 is a tank for storing the second aqueous solution L2 containing chloride ions. The chloride ions contained in the second aqueous solution L2 in the supply tank 20 permeate through the anion exchange membrane 30 and are supplied to the first aqueous solution L1 in the electrolytic tank 10.

[0018] The supply tank 20 is a tank for storing a second aqueous solution L2 containing chloride ions and supplying the chloride ions to the first aqueous solution L1. FIG. 1 illustrates the second aqueous solution L2 stored in the supply tank 20. The chloride ion concentration of the second aqueous solution L2 is higher than that of the first aqueous solution L1. To ensure safety in the event of leakage, the solute of the second aqueous solution L2 is preferably a substance classified under the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) as being as safe as sodium chloride. Specifically, the second aqueous solution L2 is a metal chloride aqueous solution containing metal ions and chloride ions. The second aqueous solution L2 is subjected to membrane electrolysis, as described below, whereby the metal ions contained in the second aqueous solution L2 react with the hydroxide ions generated by the membrane electrolysis to form a metal hydroxide precipitate. Preferably, the second aqueous solution L2 is a high-concentration magnesium chloride aqueous solution or a saturated magnesium chloride aqueous solution. When an aqueous magnesium chloride solution is used as the second aqueous solution L2, the mass percentage concentration of the aqueous magnesium chloride solution may be, for example, 1% to 35%. As an example, when the second aqueous solution L2 is an aqueous magnesium chloride solution, by performing the diaphragm electrolysis described below, magnesium ions contained in the aqueous magnesium chloride solution react with hydroxide ions generated by the diaphragm electrolysis to form a precipitate of magnesium hydroxide. The "precipitate" of magnesium hydroxide includes hard sand, colloid, slurry, and gel forms, as well as a cloudy aqueous solution.

[0019] Assuming that the space purification device is used continuously for eight hours every day for one year, the respective volumes of the electrolytic cell 10 and the supply cell 20 are preferably set so that the volume of the supply cell 20 is at least about 12 times the volume of the electrolytic cell 10. By setting such a volume ratio, the supply cell 20 can store the second aqueous solution L2 containing a sufficient amount of chloride ions necessary to supply to the first aqueous solution L1 in the electrolytic cell 10. Therefore, the supply cell 20 can stably supply chloride ions from the second aqueous solution L2 stored in the supply cell 20 to the first aqueous solution L1 stored in the electrolytic cell 10. The amount of the first aqueous solution L1 stored in the electrolytic cell 10 is, for example, about 2 mL to 10 mL.

[0020] The anion exchange membrane 30 is provided to connect the electrolytic cell 10 and the supply cell 20, and is a membranous member that allows anions to pass therethrough based on a voltage applied between the electrolytic cell 10 and the supply cell 20. More specifically, when a voltage is applied between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 (described below), membrane-type electrolysis occurs via the anion exchange membrane 30. By membrane-type electrolysis using the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21, chloride ions contained in the second aqueous solution L2 permeate the anion exchange membrane 30 and are supplied to the first aqueous solution L1 (indicated by a thick black arrow in the negative direction of the x-axis).

[0021] The anion exchange membrane 30 in this embodiment is not a type of anion exchange membrane through which anions permeate due to osmotic pressure without using electricity. Furthermore, magnesium ions, which are cations, do not permeate the anion exchange membrane 30. More specifically, when chloride ions contained in the second aqueous solution L2 permeate the anion exchange membrane 30 and are supplied to the first aqueous solution L1 by membrane electrolysis using the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21, magnesium ions, which are cations, do not permeate the anion exchange membrane 30. The anion exchange membrane 30 is, for example, a hydrocarbon-based anion exchange membrane, and includes membranes that have monovalent anion-selective permeability, alkali resistance, and high-temperature resistance.

[0022] The anion exchange membrane 30 is disposed between the electrolytic cell 10 and the supply cell 20. For example, the surface of the electrolytic cell 10 facing the supply cell 20 (the yz plane on the positive side of the x-axis) and the surface of the supply cell 20 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 opposing surfaces of the electrolytic cell 10 and the supply cell 20 are each formed by a frame-shaped member, the anion exchange membrane 30 may be disposed so as to be fitted into the frame-shaped member.

[0023] The current control unit 40 controls the current used in the diaphragmless electrolysis and the diaphragm-containing electrolysis. More specifically, the current control unit 40 controls the current used in the diaphragmless electrolysis, which is performed using a pair of electrolytic cell-side anode 11 and electrolytic cell-side cathode 12 arranged in the electrolytic cell 10. The current control unit 40 also controls the current used in the diaphragm-containing electrolysis, which is performed via the anion-exchange membrane 30 using a pair of electrolytic cell-side anode 11 and supply cell-side cathode 21, across the electrolytic cell 10 and the supply cell 20. The electrolytic cell-side anode 11 is used for both the diaphragm-less electrolysis and the diaphragm-containing electrolysis. That is, the space purification device 1 according to this embodiment includes one anode and two cathodes, for a total of three electrodes. Because the supply cell 20 includes only a cathode, chlorine is not generated within the supply cell 20 by a chemical reaction, which will be described later.

[0024] Hereinafter, the details of each component will be described in more detail with reference to FIGS.

[0025] As shown in FIG. 1 , the electrolytic cell 10 includes an electrolytic cell-side anode 11 , an electrolytic cell-side cathode 12 , a wire 13 , a wire 14 , an inlet 15 , a mixing space 16 , and an outlet 17 .

[0026] The electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 are a pair of electrodes used in the electrolysis of the first aqueous solution L1. As shown in Fig. 1 , no diaphragm such as an ion exchange membrane is provided between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. That is, the electrolysis of the first aqueous solution L1 performed using the pair of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 is diaphragm-less electrolysis. Hypochlorous acid, which is used for space purification, is produced by the diaphragm-less electrolysis of the first aqueous solution L1 performed using the pair of the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12.

[0027] The electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 each have a plate-like shape. That is, the electrolytic cell-side anode 11 is an electrolytic cell-side anode plate 11 having a plate-like shape, and the electrolytic cell-side cathode 12 is an electrolytic cell-side cathode plate 12 having a plate-like shape. Plate-like shapes include rectangular and oblong shapes. Hereinafter, the electrolytic cell-side anode 11 will also be referred to as the electrolytic cell-side anode plate 11. The electrolytic cell-side cathode 12 will also be referred to as the electrolytic cell-side cathode plate 12.

[0028] As an example, a case will be described in which the plate shapes of the electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are rectangular. The electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are 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 rectangle of each 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 electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are prevented from adhering to the upper part (positive side of the z-axis) of the electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12.

[0029] The electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are arranged such that the longitudinal direction of the rectangle is along the horizontal direction (y-axis direction). In other words, the electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are arranged such that the planes (yz planes) of their respective rectangles face each other with a predetermined gap between them. The predetermined gap is a gap appropriate for electrolysis performed using a pair of electrolytic cell-side anode plate 11 and electrolytic cell-side cathode plate 12.

[0030] The electrolytic cell-side anode plate 11 has an electrolytic cell-side anode plate immersed portion 11a and an electrolytic cell-side anode plate protruding portion 11b. Similarly, the electrolytic cell-side cathode plate 12 has an electrolytic cell-side cathode plate immersed portion 12a and an electrolytic cell-side cathode plate protruding portion 12b.

[0031] The electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are inserted from the outside of the electrolytic cell 10 toward the inside. In FIG. 1 , as an example, the electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12 are 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 and the electrolytic cell-side cathode plate immersed portion 12a inserted into the electrolytic cell 10 are positioned inside the electrolytic cell 10 and are 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 electrolytic cell-side anode plate immersed portion 11a and the electrolytic cell-side cathode plate immersed portion 12a are entirely 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 and the electrolytic cell side cathode plate immersed portion 12a.

[0032] The electrolytic cell-side anode plate protrusion 11b and the electrolytic cell-side cathode plate protrusion 12b are disposed on the exterior side of the electrolytic cell 10. Wiring 13 and wiring 14 are lines through which current flows. The electrolytic cell-side anode plate protrusion 11b is electrically connected to a current control unit 40 via wiring 13, and the electrolytic cell-side cathode plate protrusion 12b is electrically connected to a current control unit 40 via wiring 14.

[0033] Insoluble electrodes may be used as the electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12. More specifically, for example, a platinum-iridium-titanium electrode, a platinum electrode, a ruthenium-titanium electrode, or an iridium-titanium oxide electrode may be used.

[0034] The inlet 15 is an opening through which air from the space outside the casing B 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 (the x-y plane on the positive side of the z-axis) as an example, but it may be located above the liquid level S1 of the first aqueous solution L1. The shape of the inlet 15 may be, for example, cylindrical as shown in FIG. 1 or rectangular tubular. When the top surface of the electrolytic cell 10 (the surface on the positive side of the z-axis) is close to the ceiling surface of the casing B, the inlet 15 may be a hole-like opening provided in a part of the top surface of the electrolytic cell 10. Alternatively, the inlet 15 and the top surface of the casing B (the surface on the positive side of the z-axis) may be integrally formed.

[0035] 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 membrane-less electrolysis of the first aqueous solution L1 using a pair of electrolytic cell-side anode plates 11 and electrolytic cell-side cathode plates 12 with air from the external space that flows in through the inlet 15. The hypochlorous acid generated by membrane-less 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.

[0036] The outlet 17 is an opening through which mixed air, which is a mixture of air flowing in from the inlet 15 and hypochlorous acid generated by the membraneless electrolysis of the first aqueous solution L1, flows out to the space outside the casing B. That is, the outlet 17 is an opening through which the mixed air flows out to the space outside the space purification device 1. In FIG. 1 , the outlet 17 is provided on the top surface of the electrolytic cell 10 (the x-y plane on the positive side of the z-axis) as an example, similar to the inlet 15. However, it need only 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. 1 or rectangular tubular. When the top surface (the surface on the positive side of the z-axis) of the electrolytic cell 10 is close to the ceiling surface of the casing B, the outlet 17 may be a hole-like opening provided in a part of the top surface of the electrolytic cell 10. Alternatively, the outlet 17 and the top surface (the surface on the positive side of the z-axis) of the casing B may be integrally formed.

[0037] The inlet 15 and the outlet 17 may 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, moved, or installed, and to be opened or removed when the space purification device 1 is used. Although the inlet 15 and the outlet 17 are 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.

[0038] 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 B.

[0039] The supply tank 20 includes a supply tank-side cathode 21, wiring 22, and an outlet 23. The supply tank-side cathode 21 is an electrode paired with the electrolytic cell-side anode 11 and used for electrolysis of the second aqueous solution L2. As shown in FIG. 1 , an anion exchange membrane 30 is disposed between the electrolytic cell-side anode 11 and the supply tank-side cathode 21. That is, the electrolysis of the second aqueous solution L2 performed using the pair of the electrolytic cell-side anode 11 and the supply tank-side cathode 21 is membrane-less electrolysis. That is, the electrolytic cell-side anode 11 is used for both membrane-less electrolysis and membrane-with electrolysis. Chloride ions are supplied from the second aqueous solution L2 to the first aqueous solution L1 by the membrane-with electrolysis of the second aqueous solution L2 performed using the pair of the electrolytic cell-side anode 11 and the supply tank-side cathode 21.

[0040] The supply tank side cathode 21 is a supply tank side cathode plate 21 having a plate shape. The plate shape includes a rectangular shape and an oblong shape. Hereinafter, the supply tank side cathode 21 will also be referred to as a supply tank side cathode plate 21.

[0041] As an example, a case will be described in which the supply tank side cathode plate 21 also has a rectangular plate shape, similar to the electrolytic tank side anode plate 11. As shown in Fig. 1 , the supply tank side cathode plate 21 is arranged such that the shorter side of the rectangle is aligned along the vertical direction (z-axis direction). Furthermore, the supply tank side cathode plate 21 is arranged such that the longer side of the rectangle is aligned along the horizontal direction (y-axis direction).

[0042] The electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 are each in close proximity to the anion exchange membrane 30. In this specification, "close proximity" includes both a state in which the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 are close to the anion exchange membrane 30 with a predetermined gap therebetween, and a state in which the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 are in contact with the anion exchange membrane 30.

[0043] The plane of the rectangular plate on the anion exchange membrane 30 side of the electrolytic cell-side anode plate 11 (the yz plane on the positive x-axis side) is designated as plane P1. The plane of the rectangular plate on the anion exchange membrane 30 side of the supply cell-side cathode plate 21 (the yz plane on the negative x-axis side) is designated as plane P2. Planes P1 and P2 are arranged opposite each other with the anion exchange membrane 30 interposed therebetween. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21.

[0044] The electrolytic cell-side anode plate 11 is disposed between the electrolytic cell-side cathode plate 12 and the anion exchange membrane 30. This arrangement makes it possible to maintain small potential differences between the electrolytic cell-side anode plate 11 and the electrolytic cell-side cathode plate 12, and between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21.

[0045] The supply tank-side cathode plate 21 includes a supply tank-side cathode plate immersed portion 21a and a supply tank-side cathode plate protruding portion 21b. The supply tank-side cathode plate 21 is inserted from the outside of the supply tank 20 toward the inside. In FIG. 1 , as an example, the supply tank-side cathode plate 21 is inserted horizontally (in the y-axis direction) from the side of the supply tank 20 (the xz plane side on the negative side of the y-axis). The supply tank-side cathode plate immersed portion 21a inserted into the supply tank 20 is positioned inside the supply tank 20 and is entirely immersed in the second aqueous solution L2. In other words, the second aqueous solution L2 is stored in the supply tank 20 so that the entire supply tank-side cathode plate immersed portion 21a is immersed. That is, the second aqueous solution L2 is stored in the supply tank 20 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 supply tank-side cathode plate immersed portion 21a.

[0046] 1, the supply tank-side cathode plate protrusion 21b is disposed on the exterior side of the supply tank 20. The wiring 22 is a line through which current flows. The supply tank-side cathode plate protrusion 21b is electrically connected to the current control unit 40 via the wiring 22.

[0047] An insoluble electrode may be used as the supply tank side cathode plate 21. More specifically, for example, a platinum-iridium-titanium electrode, a platinum electrode, a ruthenium-titanium electrode, or an iridium-titanium oxide electrode may be used.

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

[0049] Figure 2 is a partial front cross-sectional view showing the space purification device 1 of Figure 1. The housing B shown in Figure 1 is omitted from Figure 2. As shown in Figure 2, the space purification device 1 may further include a water level detection unit 18 and a water supply unit 19. The water level detection unit 18 detects the position of the liquid level S1 in the first aqueous solution L1. The water level detection unit 18 is, for example, a water level sensor. The water level detection unit 18 is disposed above (on the positive z-axis side) the upper ends (on the positive z-axis side) of at least the electrolytic cell-side anode plate immersed portion 11a, the electrolytic cell-side cathode plate immersed portion 12a, and the supply cell-side cathode plate immersed portion 21a.

[0050] 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 does not fall below the upper ends (portions on the positive side of the z-axis) of the electrolytic cell-side anode plate immersed portion 11a, the electrolytic cell-side cathode plate immersed portion 12a, and the supply cell-side cathode plate immersed portion 21a. The water supply unit 19 may be, for example, a Peltier element that cools and condenses moisture contained in the air to form 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, for example, on the top, side, or bottom side of the electrolytic cell 10.

[0051] When the space purification device 1 is equipped with the water level detection unit 18 and the water supply unit 19, the electrolytic cell-side anode plate immersed portion 11a and the electrolytic cell-side cathode plate immersed portion 12a can be maintained immersed in the first aqueous solution L1. This prevents the electrolytic cell-side anode plate immersed portion 11a and the electrolytic cell-side cathode plate immersed portion 12a from being exposed to air due to a decrease in the first aqueous solution L1, thereby maintaining the electrolysis efficiency of diaphragm-less electrolysis.

[0052] 2, the space purification device 1 according to this embodiment includes a diaphragm-less electrolysis unit E1 and a diaphragm-containing electrolysis unit E2. The current control unit 40 controls the first current flowing through the diaphragm-less electrolysis unit E1 and the second current flowing through the diaphragm-containing electrolysis unit E2, thereby controlling the chemical reactions occurring in the diaphragm-less electrolysis unit E1 and the diaphragm-containing electrolysis unit E2.

[0053] The diaphragm-less electrolysis unit E1 is provided in the electrolytic cell 10. The diaphragm-less electrolysis unit E1 produces hypochlorous acid by electrolyzing the first aqueous solution L1 without a diaphragm by passing a first current between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12. In other words, the diaphragm-less electrolysis unit E1 includes the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12.

[0054] The membrane-equipped electrolysis unit E2 is provided across the electrolytic cell 10 and the supply cell 20. A second current is passed between the electrolytic cell-side anode 11 and the supply cell-side cathode 21, thereby performing membrane-equipped electrolysis via the anion exchange membrane 30. In other words, the membrane-equipped electrolysis unit E2 includes the electrolytic cell-side anode 11, the supply cell-side cathode 21, and the anion exchange membrane 30.

[0055] Here, we will explain in detail the chemical reaction occurring in the diaphragm-less electrolysis section E1 provided in the electrolytic cell 10 and the chemical reaction occurring in the diaphragm-containing electrolysis section E2 provided between the electrolytic cell 10 and the supply cell 20. Below, we will explain the case where the first aqueous solution L1 containing chloride ions is a sodium chloride aqueous solution and the second aqueous solution L2 is a magnesium chloride aqueous solution.

[0056] [Non-diaphragm electrolysis section E1 (electrolytic cell 10)] Fig. 3 is a list of reaction formulas occurring in the non-diaphragm electrolysis section E1. Sodium chloride (NaCl) contained in the sodium chloride aqueous solution, which is the first aqueous solution L1, converts sodium ions (Na ＋) and chloride ions (Cl － When a predetermined voltage is applied to the membraneless electrolysis section E1, a current flows, electrons move, and chemical reactions shown in reaction formulas (a) to (g) in FIG. 3 occur. Reaction formula (a) in FIG. 3: Electrolytic cell side anode 11 (chlorine generation reaction) At the electrolytic cell side anode 11, chloride ions (Cl ) ionized in water are converted into chloride ions (Cl ). － ) is an electron (e － ) and loses chlorine (Cl ２ 3 : Electrolytic cell side cathode 12 (hydrogen generation reaction) At the electrolytic cell side cathode 12, water (H ２ O) is electron (e － ) and hydrogen (H ２ ) and hydroxide ions (OH － 3: Electrolytic cell-side anode 11 (oxygen generation reaction) At the electrolytic cell-side anode 11, water (H ２ O) to electrons (e － ) is taken away, and oxygen (O ２ ) and hydrogen ions (H ＋ 3 : Reaction in the first aqueous solution L1 (hypochlorous acid generation reaction) In the first aqueous solution L1 of the electrolytic cell 10, chlorine (Cl ) generated by reaction in the reaction in the reaction in the electrolytic cell 10 is generated. ２ ) is the water (H ２ O), hydrolysis occurs, generating hydrochloric acid (HCl) and hypochlorous acid (HClO). Hydrochloric acid (HCl) ionizes in an aqueous solution, generating hydrogen ions (H ＋ ) and chloride ions (Cl － 3(e): When a voltage is applied to the anion exchange membrane 30 and a current flows through the membrane electrolysis section E2, the first aqueous solution L1 stored in the electrolytic cell 10 generates electrons (e － ) is lost. － In the first aqueous solution L1, which has lost its chloride ions (Cl), a force that maintains electrical neutrality acts, and negatively charged chloride ions (Cl － ) is supplied from the second aqueous solution L2 stored in the supply tank 20 to the first aqueous solution L1 stored in the electrolytic tank 10 through the anion exchange membrane 30. In the first aqueous solution L1, the electrons (e － ) changes to chloride ions (Cl－ 3 (f): Hypochlorous acid generating reaction (equilibrium reaction formula) The equilibrium reaction formula of the hypochlorous acid generating reaction is shown below. － Depending on the increase or decrease of Cl in the electrolytic cell 10, the equilibrium state may shift to the right or to the left. － The current control described later is performed so that the apparent increase or decrease does not occur. Equation (g) of FIG. 3: Chloride ion change equation during electrolysis The chlorine (Cl) generated by reaction equation (a) of FIG. ２ ) is converted into hydrochloric acid (HCl) and hypochlorous acid (HClO) according to reaction formula (d) in Figure 3. This can be expressed in a single formula as formula (g) in Figure 3.

[0057] Figure 4 shows a reaction formula including the ratio of the current flowing in the diaphragm-less electrolysis section E1 to the current flowing in the diaphragm-containing electrolysis section E2. Here, the ratio of the current flowing in the electrolytic cell-side anode 11 used for the chlorine generation reaction of reaction formula (a) in Figure 3 is represented by "x," and the ratio of the current used for the oxygen generation reaction of reaction formula (c) in Figure 3 is represented by "1-x." Furthermore, the ratio of the current flowing in the electrolytic cell-side anode 11 originating from the diaphragm-less electrolysis section E1 is represented by "y," and the ratio of the current originating from the diaphragm-containing electrolysis section E2 is represented by "1-y." Applying the above x and y to reaction formula (b) + (c) + (g) in Figure 3 and taking into account the change shown in (e) in Figure 3 results in reaction formula (a) in Figure 4.

[0058] When membrane-less electrolysis is performed in the membrane-less electrolysis section E1, the 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 second aqueous solution L2 stored in the supply tank 20 to the first aqueous solution L1 stored in the electrolytic cell 10.

[0059] Here, the amount of chloride ions (Cl ) consumed by the membraneless electrolysis is transferred from the second aqueous solution L2 stored in the supply tank 20 to the first aqueous solution L1 stored in the electrolytic tank 10. － ) is supplied to the electrolytic cell 10, and chloride ions (Cl － The conditions under which the apparent increase or decrease in the concentration of ClO is not observed are as follows: In this reaction, hypochlorous acid (HClO) evaporates as a gas, so it is not shown in the reaction formulas (b) to (g) shown in Figure 4. Reaction formula (b) in Figure 4: Cl－ This shows the condition under which there is no apparent increase or decrease. ・Equation (c) in Figure 4: This shows the conditional equation for coefficients x and y, which is modified from reaction equation (b) in Figure 4. ・Equation (d) in Figure 4: When equation (c) in Figure 4 is substituted into reaction equation (a) in Figure 4, reaction equation (d) in Figure 4 is obtained. ・Equation (e) in Figure 4: This shows a modification of reaction equation (d) in Figure 4.

[0060] According to reaction formula (e) in Figure 4, for example, when two electrons flow into the diaphragm-less electrolysis unit E1, x units of hypochlorous acid (HClO) are generated. For example, when four electrons flow into the diaphragm-less electrolysis unit E1, 1-x units of oxygen are generated. For example, when two electrons flow into the diaphragm-less electrolysis unit E1, 1-x / 2 units of hydrogen are generated.

[0061] 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 (e) of 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 membraneless electrolysis is transferred from the second aqueous solution L2 stored in the supply tank 20 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.

[0062] As described above, when the number of electrons flowing in the membraneless electrolysis section E1 changes, that is, when the ratio of the current flowing in the membraneless electrolysis section E1 to the current flowing in the membraneless electrolysis section E2 changes, the amount of chloride ions supplied from the supply tank 20 to the electrolytic cell 10 changes. For example, when the ratio of the current used for membraneless electrolysis changes, the 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 (f) in FIG. 4), the Cl － The supply amount of Cl in the electrolytic cell 10 decreases. － decreases.

[0063] Cl in the electrolytic cell 10 －If the electrolysis without a diaphragm is continued in a state where the electrolysis efficiency is reduced, the Cl in the electrolytic cell 10 will gradually decrease. － increases, and Cl － reaches a level that does not appear to increase or decrease.

[0064] On the other hand, the amount of current used for membraneless electrolysis is such that chloride ions (Cl － ) is supplied to the electrolytic cell 10, and Cl － is larger than the current amount under the condition that there is no apparent increase or decrease (reaction formula (g) in FIG. 4 below), Cl supplied from supply tank 20 to electrolytic tank 10 － The supply amount of Cl in the electrolytic cell 10 increases. － increases.

[0065] Chloride ions (Cl) in the electrolytic cell 10 － ) increases, the electrolysis efficiency of membrane-less electrolysis increases. If membrane-less electrolysis is continued in a state where the electrolysis efficiency has increased, the Cl in the electrolytic cell 10 gradually increases. － decreases, and Cl － reaches a level that does not appear to increase or decrease.

[0066] 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 (f) in FIG. 3 shifts to the left, and the amount of chlorine generated increases. － By adjusting the current flowing through the membraneless electrolysis section E1 and the current flowing through the membrane-containing 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.

[0067] [Diaper membrane electrolysis section E2] Fig. 5 is a list of reaction formulae that occur in the diaphragm membrane electrolysis section E2. The reactions in the second aqueous solution L2 in the supply tank 20 will be described. The only electrode arranged in the supply tank 20 is the supply tank side cathode 21. When a predetermined voltage is applied to the diaphragm membrane electrolysis section E2, a current flows, electrons move, and the chemical reaction shown in Fig. 5 occurs. Reaction formula (a) in Fig. 5: Supply tank side cathode 21 (hydrogen generation reaction) At the supply tank side cathode 21, water (H ２ O) is electron (e － ) and hydrogen (H ２) and hydroxide ions (OH － ) is generated. Hydrogen volatilizes as a gas, and hydroxide ions are used in reaction formula (c) of FIG. 5, which will be described later. ・FIG. 5(b): When a voltage is applied to the anion exchange membrane 30 and a current flows through the membrane electrolysis section E2, chloride ions (Cl － ) passes through the anion exchange membrane 30 and is supplied to the first aqueous solution L1, and the second aqueous solution L2 passes through the supply tank side cathode 21 and receives electrons (e － In other words, in the second aqueous solution L2, the chloride ions (Cl － ) after the change, electrons (e － ) in the reaction formula (c) of FIG. 5: In the second aqueous solution L2 (magnesium hydroxide precipitation reaction) The magnesium ions (Mg ２＋ ) and hydroxide ions (OH － ) reacts with magnesium hydroxide (Mg(OH) ２ ) precipitate is formed. Magnesium hydroxide (Mg(OH) ２ ) is solubility product Ksp = 1.2 × 10 －１１ (mol / L) ３ It is a substance that is very difficult to dissolve in aqueous solutions with a pH ranging from neutral to alkaline. For example, the concentration of magnesium hydroxide that can be dissolved in a weakly alkaline aqueous solution with a pH of 10 is only 1.2 × 10 －３ In the second aqueous solution L2 of the supply tank 20, hydroxide ions (OH － ) is used to generate magnesium hydroxide precipitate, thereby generating hydroxide ions (OH － ) and the increase in pH of the second aqueous solution L2 can be suppressed.

[0068] Furthermore, when a magnesium chloride aqueous solution is used as the second aqueous solution L2, the pH of the magnesium hydroxide saturated aqueous solution produced after membrane electrolysis, in which magnesium hydroxide is saturated, is pH 10.36 as determined from the solubility product. Therefore, even after membrane electrolysis is performed over a long period of time, the pH of the second aqueous solution L2 can be maintained in a weakly alkaline state of up to 10.36 or less. In other words, when a magnesium chloride aqueous solution is used as the second aqueous solution L2, it is possible to prevent the second aqueous solution L2 from becoming strongly alkaline, with a pH of 11 or more. Therefore, it is possible to provide a space purification device 1 that is safer by preventing the second aqueous solution L2 stored in the supply tank 20 from becoming strongly alkaline after electrolysis.

[0069] Furthermore, for example, the space purification device 1 according to this embodiment may be installed by a contractor. After use, the space purification device 1 may be overturned or dropped when the contractor removes the installed space purification device or during transportation after removal. In this case, if a magnesium chloride aqueous solution is used as the second aqueous solution L2, the second aqueous solution L2 after the electrolysis reaction is a weakly alkaline magnesium hydroxide aqueous solution. Therefore, even if the second aqueous solution L2 leaks outside the space purification device 1 due to overturning or dropping, safety can be improved compared to space purification devices using a sodium chloride aqueous solution.

[0070] The above is a detailed description of the chemical reaction occurring in the membraneless electrolysis section E1 provided in the electrolytic cell 10 and the chemical reaction occurring in the membrane-containing electrolysis section E2 provided across the electrolytic cell 10 and the supply cell 20.

[0071] The current control unit 40 controls the chemical reaction. More specifically, the current control unit 40 applies the second current, causing chloride ions contained in the second aqueous solution L2 to permeate through the anion exchange membrane 30 and be supplied to the first aqueous solution L1. The current control unit 40 also applies the first current and the second current at a predetermined current ratio so that the concentration of hypochlorous acid (liquid) in the first aqueous solution L1 is maintained at a predetermined concentration.

[0072] As described above, in the first aqueous solution L1 stored in the electrolytic cell 10, chlorine (Cl ２(liquid, aq.)) and hypochlorous acid (HClO (liquid)) are generated and reach an equilibrium state, but Cl supplied from the second aqueous solution L2 to the first aqueous solution L1 － The equilibrium state can change depending on the increase or decrease in (see reaction equations (a), (d), and (f) in FIG. 3). Here, the amount of chlorine (gas) volatilized from the first aqueous solution L1 stored in the electrolytic cell 10 is proportional to the concentration of chlorine (liquid) in the first aqueous solution L1. Similarly, the amount of hypochlorous acid (gas) volatilized from the first aqueous solution L1 stored in the electrolytic cell 10 is proportional to the concentration of hypochlorous acid (liquid) in the first aqueous solution L1.

[0073] The ratio of the amounts of chlorine (liquid) and hypochlorous acid (liquid) generated in the first aqueous solution L1 stored in the electrolytic cell 10 is determined by the current ratio between the first current and the second current. In other words, the ratio of the amounts of chlorine (gas) and hypochlorous acid (gas) generated that volatilize from the first aqueous solution L1 stored in the electrolytic cell 10 is determined by the current ratio between the first current and the second current. More specifically, with regard to the current ratio between the first current and the second current, when the amount of the first current flowing through the diaphragm-less electrolysis unit E1 is made larger than the amount of the second current flowing through the diaphragm-containing electrolysis unit E2, the amount of chlorine (gas) generated that volatilizes from the first aqueous solution L1 decreases, and the amount of hypochlorous acid (gas) generated increases.

[0074] FIG. 6 is a graph showing the correlation between the amount of hypochlorous acid (gas) and chlorine (gas) generated and the current rate. The current control unit 40 controls the current rate between the first current and the second current so that the amount of the first current is greater than the amount of the second current. The current control unit 40 controls the first current and the second current so that they flow at a predetermined current rate. The current rate between the amount of the first current and the amount of the second current is calculated by dividing the amount of the first current by the amount of the second current. As shown in FIG. 6, when the amount of the first current is increased, the amount of hypochlorous acid (HClO, gas, shown by the black line) generated (mL / hour) increases, and the amount of chlorine (Cl ２ , gas (shown by the dashed line) is generated (mL / hour).

[0075] The predetermined current ratio between the first current and the second current is a current ratio at which the amount of hypochlorous acid (gas) generated exceeds the amount of chlorine (gas). The current ratio between the first current and the second current at which the amount of hypochlorous acid (gas) generated exceeds the amount of chlorine (gas) generated is, for example, when the amount of the first current is more than n times the amount of the second current (n is an arbitrary positive number, shown by the dashed line). For example, when platinum electrodes are used as each electrode, n may be set to 5, preferably n = 7. Furthermore, for example, when iridium titanium oxide electrodes are used as each electrode, n may be set to 15, preferably n = 17. By setting n to this value, the amount of hypochlorous acid (gas) generated can exceed the amount of chlorine (gas). By generating hypochlorous acid (gas) at a rate exceeding the amount of chlorine (gas), a space purification device 1 with improved safety can be provided. Note that the value of n is not limited to these and can be changed as appropriate depending on the type of electrode used.

[0076] The inventors discovered a problem that would occur if the above current ratio were maintained unchanged, for example, when the electrode catalyst elutes and the electrodes deteriorate over the course of a predetermined operating time of the space purification device 1. Deterioration of the electrodes reduces the electrolysis efficiency in the diaphragm-less electrolysis unit E1 and the diaphragm-containing electrolysis unit E2, potentially making it difficult to stably supply hypochlorous acid. Therefore, the current control unit 40 controls the ratio of the first current to the second current to change the current ratio in accordance with the predetermined operating time of the space purification device 1, so that the concentration of hypochlorous acid (liquid) in the first aqueous solution L1 is maintained at a predetermined concentration.

[0077] 7 is a block diagram showing the current control unit 40 according to the embodiment. As shown in FIG. 7, the current control unit 40 includes an operating time acquisition unit 41 and a storage unit 42. The operating time acquisition unit 41 acquires the cumulative operating time of the space purification device 1. The storage unit 42 stores the cumulative operating time of the space purification device 1 acquired by the operating time acquisition unit 41 in association with the current ratio between the first current and the second current. When a predetermined operating time of the space purification device 1 has elapsed, the current control unit 40 performs control to change the current ratio between the first current and the second current based on the storage unit 42.

[0078] As described above, when the amount of the first current is more than n times the amount of the second current, the amount of chlorine (gas) generated decreases and the amount of hypochlorous acid (gas) generated increases. In other words, the amount of hypochlorous acid (gas) generated exceeds the amount of chlorine (gas) generated (see FIG. 6 ). The current control unit 40 changes the current ratio by controlling the amount of the first current to the amount of the second current based on the memory unit 42. The amount of the first current is increased according to the predetermined operating time of the space purification device 1, while the amount of the second current is maintained unchanged. Because the current control unit 40 increases the amount of the first current according to the predetermined operating time, the total current amount, which is the sum of the amounts of the first current and the second current, also increases. Here, in order to suppress deterioration of each electrode, the current density at each electrode when the amount of the first current is increased is, for example, up to 30 A / dm ２ The following applies.

[0079] As described above, the current control unit 40 controls the current ratio between the first current and the second current, so that the concentration of hypochlorous acid (liquid) in the first aqueous solution L1 can be maintained at a predetermined concentration while supplying a required amount of chloride ions from the second aqueous solution L2 in the supply tank 20 to the first aqueous solution L1 in the electrolytic tank 10. Furthermore, even if the electrodes deteriorate, the amount of the first current can be increased according to the specified operating time of the space purification device 1 while the amount of the second current is maintained unchanged, thereby supplying a required amount of chloride ions from the second aqueous solution L2 in the supply tank 20 to the first aqueous solution L1 in the electrolytic tank 10.

[0080] As described above, the space purification device 1 can stably generate a desired amount of hypochlorous acid gas because the chloride ions consumed by the first aqueous solution L1 can be appropriately supplied from the second aqueous solution L2. Therefore, the space purification device 1 can stably generate a desired amount of hypochlorous acid gas for a long period of time, such as one year, without externally supplying an aqueous solution containing chloride ions.

[0081] The current control unit 40 may control the amount of the first current so that the amount of the first current is greater than the amount of the second current, and may increase the amount of the first current while increasing the amount of the second current. When the amount of the first current is also increased, it is preferable that the amount of the first current is more than n times the amount of the second current, as described above.

[0082] In the present embodiment, the memory unit 42 included in the current control unit 40 stores the cumulative operating time of the space purification device 1 acquired by the operating time acquisition unit 41 in association with the current ratio between the first current and the second current, but this is not limited to this. As electrode deterioration progresses, for example, the voltage between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 increases. Therefore, instead of the operating time acquisition unit 41, for example, a voltage acquisition unit (not shown) that acquires the voltage between the electrolytic cell-side anode 11 and the electrolytic cell-side cathode 12 may be provided. The voltage acquisition unit is, for example, a voltmeter. The memory unit 42 may store the voltage acquired by the voltage acquisition unit in association with the current ratio between the first current and the second current. When the voltage acquisition unit acquires a predetermined voltage value, the current control unit 40 changes the current ratio between the first current and the second current. More specifically, the current control unit 40 performs control to increase the amount of the first current relative to the amount of the second current based on the memory unit 42.

[0083] It is also possible to provide a plurality of current control units 40 and control the first current and the second current separately.

[0084] A case will now be described in which no electrode deterioration or the like occurs and the concentration of hypochlorous acid (liquid) in the first aqueous solution L1 does not decrease even after a predetermined operating time. The current control unit 40 may pass the second current, thereby causing chloride ions contained in the second aqueous solution L2 to permeate the anion exchange membrane 30 and be supplied to the first aqueous solution L1. Alternatively, the current control unit 40 may pass the first current and the second current at a predetermined current ratio so that the concentration of hypochlorous acid (liquid) in the first aqueous solution L1 is maintained at a predetermined concentration. As described above, the current ratio between the first current and the second current is such that the amount of the first current is more than n times the amount of the second current. In other words, if no electrode deterioration or the like occurs, the current control unit 40 may maintain the current ratio at a predetermined value without controlling the current ratio between the first current and the second current to change it according to the predetermined operating time.

[0085] 2, the inlet 15 and the outlet 17 are arranged on the front left side (negative side of the y-axis and negative side of the x-axis) and the back right side (positive side of the y-axis and positive side of the x-axis) when the electrolytic cell 10 is viewed in plan, 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. However, when the inlet 15 and the outlet 17 are arranged, it is preferable to arrange them so that they are at the farthest positions on the xy plane. With this arrangement, the time during which the inflowing air and hypochlorous acid are mixed in the mixing space 16 is longer, and therefore, more hypochlorous acid can be contained in the mixed air.

[0086] Next, a case will be described in which plane P1 (the yz plane on the positive x-axis side) of the rectangular plate on the anion exchange membrane 30 side of the electrolytic cell-side anode plate 11 and plane P2 (the yz plane on the negative x-axis side) of the rectangular plate on the anion exchange membrane 30 side of the supply cell-side cathode plate 21 do not face each other. When the planes of each rectangle are arranged parallel to the xy plane, a non-uniform electric field may be generated between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21. When a non-uniform electric field is generated between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21, the current distribution between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 also becomes non-uniform.

[0087] When the current distribution between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 becomes uneven, regions of high and low current density are generated. In the high current density areas, the catalytic layer on the surfaces of the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21 (hereinafter also referred to as each electrode plate) is more likely to deteriorate, while in the low current density areas, the catalytic layer on the surfaces of each electrode plate is less likely to deteriorate. That is, when an uneven electric field is generated between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21, the current distribution becomes uneven, and regions of different current densities may exist simultaneously on the same electrode plate. Therefore, the deterioration of the catalytic layer due to the use of each electrode plate may occur unevenly. If the degree of deterioration of the catalytic layer on the surfaces 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 easily reduced.

[0088] In contrast, in the spatial purification device 1 according to this embodiment, the planes P1 and P2 are arranged opposite each other with the anion exchange membrane 30 interposed therebetween. This arrangement allows a uniform electric field to be generated between the electrolytic cell-side anode plate 11 and the supply cell-side cathode plate 21, resulting in a uniform distribution of current 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. Therefore, a decrease in electrolysis efficiency can be suppressed.

[0089] When membraneless electrolysis is performed in the electrolytic cell 10 at room temperature and normal pressure, the electrolyte of the first aqueous solution L1 is not used in the electrolysis, and oxygen and chlorine are mainly generated from the anode. The electrolyte does not react with hypochlorous acid to reduce the concentration of hypochlorous acid, and is non-reactive with the electrodes, the electrolytic cell 10, and the anion exchange membrane 30. The electrolyte may be electrically conductive and non-reactive with the electrodes, the electrolytic cell 10, and the anion exchange membrane 30. More specifically, in addition to the first aqueous solution L1 described above, the first aqueous solution L1 may be, for example, a metal chloride aqueous solution, a hydroxide salt aqueous solution, an acid salt aqueous solution, a phosphate aqueous solution, or a combination thereof. The metal chloride aqueous solution may be, for example, a dilute calcium chloride aqueous solution or a dilute magnesium chloride aqueous solution. The hydroxide salt aqueous solution may be, for example, a dilute sodium hydroxide aqueous solution or a dilute potassium hydroxide aqueous solution of 0.4 wt % (0.1 mol / L) or less. The acid salt aqueous solution may be, for example, a dilute hydrochloric acid aqueous solution of 0.4 wt % (0.1 mol / L) or less. The phosphate aqueous solution may be, for example, a disodium hydrogen phosphate aqueous solution, a sodium dihydrogen phosphate aqueous solution, a dipotassium hydrogen phosphate aqueous solution, or a potassium dihydrogen phosphate aqueous solution. As a specific example of a combination of the first aqueous solution L1, the pH may be adjusted by combining a dilute sodium chloride aqueous solution with a dilute sodium hydroxide aqueous solution.

[0090] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present disclosure.

[0091] An outline of one aspect of the present disclosure is as follows.

[0092] (Item 1) An electrolytic cell (10) for storing a first aqueous solution (L1) containing chloride ions; a supply tank (20) for storing a second aqueous solution (L2) containing chloride ions at a higher concentration than the first aqueous solution (L1) and for supplying chloride ions to the first aqueous solution (L1); an electrolytic cell-side anode (11) and an electrolytic cell-side cathode (12) provided in the electrolytic cell (10); a supply tank-side cathode (21) provided in the supply tank (20); and an anion exchange membrane (30) provided to connect the electrolytic cell (10) and the supply tank (20), which allows anions to pass through based on a voltage applied between the electrolytic cell-side anode (11) and the supply tank-side cathode (21). a diaphragm-less electrolysis unit (E1) provided in the electrolytic cell (10) for generating hypochlorous acid by performing diaphragm-less electrolysis of the first aqueous solution (L1) by passing a first current between the electrolytic cell-side anode (11) and the electrolytic cell-side cathode (12); a diaphragm-containing electrolysis unit (E2) provided between the electrolytic cell (10) and the supply tank (20) for performing diaphragm-containing electrolysis via the anion exchange membrane (30) by passing a second current between the electrolytic cell-side anode (11) and the supply tank-side cathode (21); and a current control unit (40) for supplying chloride ions contained in the second aqueous solution (L2) stored in the supply tank (20) to the first aqueous solution (L1) by passing them through the anion exchange membrane (30) so as to compensate for chloride ions contained in the first aqueous solution (L1) that have decreased due to the diaphragm-less electrolysis, wherein the current control unit (40) By passing the second current, chloride ions contained in the second aqueous solution (L2) are permeated through the anion exchange membrane (30) and supplied to the first aqueous solution (L1), and the first current and the second current are passed at a predetermined current ratio, and the current ratio is controlled to be changed according to a predetermined operating time, so that the concentration of hypochlorous acid in the first aqueous solution (L1) is maintained at a predetermined concentration.

[0093] (Item 2) The space purification device (1) according to Item 1, wherein the current control unit (40) includes a memory unit (42) that stores an operating time of the space purification device (1) and a current ratio between the first current and the second current in association with each other, and performs control to change the current ratio based on the memory unit when the predetermined operating time has elapsed.

[0094] (Item 3) The space purification device (1) according to Item 2, wherein the current control unit (40) changes the current ratio by increasing the amount of the first current relative to the second current based on the memory unit (42).

[0095] (Item 4) The space purification device (1) according to Item 2 or Item 3, wherein a total current amount, which is the sum of the current amount of the first current and the current amount of the second current, is increased with the predetermined operation time.

[0096] (Item 5) The space purification device (1) according to Item 1, comprising: a housing (B) that houses the electrolytic cell (10) and the supply tank (20); an inlet (15) that is disposed within the housing above the liquid level 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; and an outlet (17) through which the mixed air flows out to the external space.

[0097] 1 Space purification device 10 Electrolytic cell 11 Anode on the electrolytic cell side 11a Anode plate immersion part on the electrolytic cell side 11b Anode plate protrusion on the electrolytic cell side 12 Cathode on the electrolytic cell side 12a Cathode plate immersed part on the electrolytic cell side 12b Cathode plate protrusion on the electrolytic cell side 13 Wiring 14 Wiring 15 Inlet 16 Mixing space 17 Outlet 18 Water level detection section 19 Water supply section 20 Supply tank 21 Supply tank side cathode 21a Supply tank side cathode plate immersion section 21b Supply tank side cathode plate protrusion section 22 Wiring 23 Discharge port 30 Anion exchange membrane 40 Current control section 41 Operating time acquisition section 42 Storage section B Housing L1 First aqueous solution L2 Second aqueous solution S1 Liquid level S2 Liquid level E1 Non-diaphragm electrolytic part E2 Diaphragm electrolysis section P1 plane P2 plane

Claims

1. An electrolytic cell for storing a first aqueous solution containing chloride ions; a supply cell for storing a second aqueous solution containing a higher concentration of chloride ions than the first aqueous solution and for supplying chloride ions to the first aqueous solution; an electrolytic cell-side anode and an electrolytic cell-side cathode provided in the electrolytic cell; a supply cell-side cathode provided in the supply cell; an anion exchange membrane provided to connect the electrolytic cell and the supply cell and allowing anions to pass through based on a voltage applied between the electrolytic cell-side anode and the supply cell-side cathode; a membrane-less electrolysis section provided in the electrolytic cell for generating hypochlorous acid by performing membrane-less electrolysis of the first aqueous solution by passing a first current between the electrolytic cell-side anode and the electrolytic cell-side cathode; and a membrane-with electrolysis section provided between the electrolytic cell and the supply cell for performing membrane-with electrolysis via the anion exchange membrane by passing a second current between the electrolytic cell-side anode and the supply cell-side cathode. a current control unit that supplies chloride ions contained in the second aqueous solution stored in the supply tank through the anion exchange membrane to the first aqueous solution so as to replenish chloride ions contained in the first aqueous solution that have been reduced by the diaphragm-less electrolysis, wherein the current control unit applies the second current so as to supply chloride ions contained in the second aqueous solution through the anion exchange membrane to the first aqueous solution, and applies the first current and the second current at a predetermined current ratio and controls to change the current ratio in accordance with a predetermined operating time so that the hypochlorous acid concentration in the first aqueous solution is maintained at a predetermined concentration.

2. The space purification device according to claim 1, wherein the current control unit includes a memory unit that stores the operating time of the space purification device and the current ratio of the first current to the second current in association with each other, and when the predetermined operating time has elapsed, controls to change the current ratio based on the memory unit.

3. The space purification device according to claim 2, wherein the current control unit changes the current ratio by increasing the amount of the first current relative to the second current based on the memory unit.

4. The space purification device according to claim 2 or 3, wherein the total current amount, which is the sum of the current amount of the first current and the current amount of the second current, is increased as the predetermined operating time increases.

5. The space purification device according to claim 1, comprising: a housing that houses the electrolytic cell and the supply cell; an inlet that is positioned within the housing above the liquid level of the first aqueous solution stored in the electrolytic cell and 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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