Air purification system and air purification method

Abstract

An air purification system (1) includes an ozone generator (40) that generates ozone gas and an emission unit (50) that atomizes or vaporizes and emits an alcohol aqueous solution. A mole fraction of alcohol included in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less. Hydroxyl radicals are generated by a reaction of the ozone gas and the alcohol aqueous solution that is atomized or vaporized.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an air purification system and an air purification method. BACKGROUND

[0002] An air purifier using a filter such as a HEPA filter for purifying an indoor space has been on the market. However, such an air purifier cannot sterilize or inactivate microorganisms such as viruses and bacteria. On the other hand, since ozone gas has strong oxidizing power, it is used to sterilize or inactivate microorganisms such as viruses and bacteria present in the space and on the surface of objects. However, it is known that a high concentration of ozone gas can cause damage to human health, and the Japan Society for Occupational Health recommends that the ozone allowable concentration be 0.1 ppm or less. On the other hand, if the ozone gas concentration in the room is 0.1 ppm or less, the sterilization or inactivation effect of microorganisms is small, so a high concentration of ozone gas is fumigated during the time when a person is not in the room, as described in Patent Literature 1.

[0003] In Patent Literature 1, an air purifier is disclosed that has a first air vent that communicates with an indoor space, an ozone generating portion, an ozone decomposing portion, and a second air vent that communicates with the indoor space. The ozone generating portion is located between the first air vent and the ozone decomposing portion. A shut-off unit that can be opened and closed and that can cut off the flow of ozone gas when closed is provided between the ozone generating portion and the ozone decomposing portion.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2002-126063 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The conventional air purifier opens the shut-off unit when a person is in the room and decomposes ozone gas in the ozone decomposing portion. In addition, the conventional air purifier closes the shut-off unit when a person is not in the room, and removes the odor and odor source in the indoor space using ozone gas generated by the ozone generating portion. However, in the conventional air purifier, a high concentration of ozone gas cannot be used during the time when a person is in the room. Therefore, in the case where an infected person who has contracted an infectious disease is in the room, droplets containing an infection source such as the above-described microorganisms are scattered into the indoor space due to coughing and the like, and adhere to and accumulate on the surface of objects, so there is a risk that the risk of infection from the infected person to other people becomes high.

[0009] Therefore, an object of the present disclosure is to provide an air purification system and an air purification method that can purify air by hydroxyl radicals generated by adding an additive to ozone gas.

[0010] Method for solving the problem

[0011] The air purification system of the present disclosure is provided with an ozone generating section that generates ozone gas and an emitting section that atomizes or vaporizes and emits an alcohol aqueous solution. The mole fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less. Hydroxyl radicals are generated by the reaction of ozone gas with the alcohol aqueous solution that has been atomized or vaporized.

[0012] The alcohol can include at least any one of ethanol and isopropyl alcohol. The alcohol can be emitted in a manner of 12 times or less in terms of volume ratio with respect to ozone gas when converted to a gas. The air purification system can further be provided with a first housing that houses the ozone generating section and the emitting section, and the ozone gas and the alcohol aqueous solution that has been atomized or vaporized can react on the inside of the first housing. The air purification system can further be provided with a first housing that houses the ozone generating section and the emitting section, and the ozone gas and the alcohol aqueous solution that has been atomized or vaporized can react on the outside of the first housing. The air purification system can further be provided with a second housing that houses the ozone generating section and a third housing that houses the emitting section, and the ozone gas and the alcohol aqueous solution that has been atomized or vaporized can react on the outside of the second housing and the third housing. The ozone gas concentration in the outside space can be controlled to be 0.1 ppm or less.

[0013] The air purification method of the present disclosure includes a process of generating ozone gas, a process of emitting an alcohol aqueous solution that has been atomized or vaporized, and a process of generating hydroxyl radicals by the reaction of ozone gas with the alcohol aqueous solution that has been atomized or vaporized. The mole fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less.

[0014] Effects of the Invention

[0015] According to the present disclosure, it is possible to provide an air purification system and an air purification method that can purify air by hydroxyl radicals generated by adding an additive to ozone gas. BRIEF DESCRIPTION OF DRAWINGS

[0016] [ Figure 1 ] Figure 1 is a schematic view showing an air purification system of one embodiment.

[0017] [ Figure 2 ] Figure 2 is a schematic view showing an air purification system of another embodiment.

[0018] [ Figure 3 ] Figure 3 is a schematic view showing an air purification system of another embodiment.

[0019] [ Figure 4 ] Figure 4This is a graph showing the relationship between the molar fraction of alcohol and the fluorescence peak height of hydroxyl radicals. Detailed Implementation

[0020] Hereinafter, several exemplary embodiments will be described with reference to the accompanying drawings. It should be noted that, for ease of explanation, the scale of the drawings has been exaggerated and may sometimes differ from the actual scale.

[0021] [First Implementation Method]

[0022] First, use Figure 1 The air purification system 1 of the first embodiment will be described. For example... Figure 1 As shown, the air purification system 1 of this embodiment includes an air purification device 2. The air purification device 2 includes a first housing 10, a filter section 20, an air supply section 30, an ozone generating section 40, an emission section 50, and a control section 60. However, the air purification device 2 only needs to include the ozone generating section 40 and the emission section 50; it is not necessary to include the first housing 10, the filter section 20, the air supply section 30, and the control section 60. In the air purification system 1 of this embodiment, as described later, ozone gas generated by the ozone generating section 40 reacts with an alcohol-water solution released from the emission section 50 as an additive to generate hydroxyl radicals. Then, the air purification system 1 purifies the air using hydroxyl radicals.

[0023] Ozone (O3) has a high redox potential of 2.07V, exhibiting extremely strong oxidizing power. Therefore, ozone gas can be used for sterilization and virus inactivation. Furthermore, the hydroxyl radicals (OH·) generated in the air from a portion of the ozone gas reaction have an even higher redox potential of 3.85V, exhibiting the strongest oxidizing power among molecules containing oxygen atoms. However, under normal conditions without additives, it is difficult for ozone gas to generate hydroxyl radicals. Therefore, in the air purification system 1 of this embodiment, the unreacted portion of the ozone gas reacts with an alcohol-water solution as an additive to generate highly oxidizing hydroxyl radicals, increasing the concentration of hydroxyl radicals in the space and thereby enhancing the bactericidal effect.

[0024] The first housing 10 accommodates a filter section 20, a blower section 30, an ozone generation section 40, a discharge section 50, and a control section 60. The first housing 10 divides an internal space of the air purifying device 2 and an indoor space which is an external space. An air suction port 11 for sucking air from the outside of the first housing 10 and an air discharge port 12 for discharging air sucked from the air suction port 11 to the outside of the first housing 10 are provided in the first housing 10. An air flow path 13 connecting the air suction port 11 and the air discharge port 12 is provided in the inside of the first housing 10, and air flows in the air flow path 13 from the air suction port 11 toward the air discharge port 12. In the air flow path 13, the filter section 20, the blower section 30, and the ozone generation section 40 are arranged in this order from the upstream side.

[0025] The filter section 20 is provided in the air suction port 11, and removes foreign matter from air sucked from the outside of the first housing 10. The filter section 20 can also include, for example, a publicly known dust filter. In addition, the filter section 20 can include, in addition to the dust filter, a publicly known functional filter.

[0026] The blower section 30 is provided in the air flow path 13 on the downstream side of the filter section 20. The blower section 30 causes air to flow into the inside of the first housing 10 from the outside of the first housing 10 through the air suction port 11, and causes air flowing into the first housing 10 to be discharged to the outside of the first housing 10 through the air discharge port 12. The blower section 30 can also include, for example, a Silo fan. The blower section 30 is arranged in the downstream side of the filter section 20 in the drawing, but can generate an air current from the air suction port 11 toward the air discharge port 12 if arranged in the air flow path 13. Therefore, the blower section 30 can also be arranged, for example, in the vicinity of the air discharge port 12.

[0027] The ozone generation section 40 generates ozone gas. The ozone gas is ozone of a gas. Specifically, the ozone generation section 40 generates ozone gas from oxygen in air sucked from the outside of the first housing 10. The ozone gas generated by the ozone generation section 40 is discharged to the outside of the first housing 10 through the air discharge port 12. The ozone generation section 40 is not particularly limited as long as it can generate ozone gas, and can include, for example, a discharge-type ozone generator such as a corona discharge and a silent discharge, or an ultraviolet lamp-type ozone generator. The amount of ozone gas generated by the ozone generation section 40 can be adjusted, for example, by changing the output of the ozone generation section 40, the ozone generation time, and the like.

[0028] The air purifying system 1 can also be provided with an ozone concentration sensor that measures the concentration of ozone gas on at least either the outside or the inside of the first housing 10. In the case of measuring the concentration of ozone gas on the outside of the first housing 10, the concentration of indoor ozone gas after the ozone gas has reacted with the alcohol aqueous solution is measured, and thus a direct indicator of the amount of indoor ozone gas can be obtained. On the other hand, in the case of measuring the concentration of ozone gas on the inside of the first housing 10, the ozone concentration sensor is disposed, for example, on the downstream side of the ozone generating portion 40 in the air flow path 13. In this case, the ozone concentration sensor can directly measure the concentration of ozone gas generated by the ozone generating portion 40, and thus an indicator of the amount of ozone gas generated by the ozone generating portion 40 can be obtained. Therefore, the amount of ozone gas generated can be easily adjusted according to the state of the ozone generating portion 40.

[0029] The concentration of ozone gas in the external space in the air purifying system 1 is preferably controlled to be 0.1 ppm or less. Thereby, even in the case where a person is present in the room, the air can be purified by the air purifying system 1. The concentration of ozone gas in the external space can be controlled to be 0.08 ppm or less. The air purifying system 1 can decontaminate by the hydroxyl radical, and thus the lower limit of the concentration of ozone gas in the external space is not particularly limited, and can be controlled to be 0.01 ppm or more, for example. Note that ppm in this specification means parts per million by volume.

[0030] The concentration of ozone gas generated by the ozone generating portion 40 is not particularly limited. As described above, the concentration of ozone gas in the external space is preferably 0.1 ppm or less. However, since the ozone gas reacts with the alcohol aqueous solution to generate the hydroxyl radical, at least a part of the ozone gas generated by the ozone generating portion 40 disappears by reacting with the alcohol aqueous solution. Therefore, the concentration of ozone gas generated by the ozone generating portion 40 can also exceed 0.1 ppm. However, from the viewpoint of further reducing the concentration of ozone gas in the atmosphere on the outside of the first housing 10, it is preferable to control the concentration of ozone gas generated by the ozone generating portion 40 to be 0.1 ppm or less. In addition, by setting the concentration of ozone gas to be 0.1 ppm or less, deterioration of specific materials due to ozone gas can be suppressed. The concentration of ozone gas generated by the ozone generating portion 40 can also be controlled to be 0.08 ppm or less. In addition, the air purifying system 1 can purify the air by the hydroxyl radical, and thus the lower limit of the concentration of ozone gas generated by the ozone generating portion 40 is not particularly limited, and can be controlled to be 0.01 ppm or more, for example.

[0031] The discharge portion 50 discharges the alcohol aqueous solution by atomizing or vaporizing it. Then, the ozone gas generated by the ozone generating portion 40 reacts with the alcohol aqueous solution after atomization or vaporization, and thereby the hydroxyl radical is generated. At this time, the alcohol aqueous solution after atomization or vaporization can be supplied to the ozone gas, or the ozone gas can be supplied to the alcohol after atomization or vaporization.

[0032] Hydroxyl radicals are one kind of radicals, for example, capable of decomposing by abstracting hydrogen from organic matter such as proteins and lipids constituting microorganisms, and have bactericidal or viral inactivating effects. Hydroxyl radicals have a higher oxidation-reduction potential than ozone, and have sufficient bactericidal or inactivating effects even at a low concentration of hydroxyl radicals. For example, if CT values (Concentration-Time Values) required for 99% sterilization of Escherichia coli are compared, it is said that hydroxyl radicals are several hundredth or less of the CT value of ozone.

[0033] Therefore, according to the air purification system 1 of the present embodiment, by the action of hydroxyl radicals, even at a low concentration of ozone gas, bacteria can be effectively sterilized and viruses can be inactivated. In addition, hydroxyl radicals have high reactivity, and become water by combining with abstracted hydrogen, and thus have low residual properties. Furthermore, hydroxyl radicals can decompose organic matter by high oxidizing power, and thus can be applied not only to sterilization of bacteria and inactivation of viruses, but also to deodorization, bleaching, and cleaning, and the like.

[0034] Note that it is said that the CT value required for 99% sterilization of Escherichia coli by hydroxyl radicals is 4.7 x 10 -10It is expected that other bacteria and viruses and the like also have the same tendency. On the other hand, in the case where the ozone gas concentration is 0.1 ppm and the relative humidity is 80% (corresponding to so-called ozone mist), the new coronavirus (SARS-CoV-2) was reduced by 27% at CT (ppm x min) = 24, 13% at CT = 42, and 4.6% at CT = 60, and the TCID50was reduced. If this value is approximated by an exponential function, it can be estimated that the TCID50is 1% at about CT = 92. That is, the 99% inactivation time at an ozone gas concentration of 0.1 ppm is 920 minutes, or about 15 hours. As in the example described later, in the case where an additive is added to the gas at an ozone gas concentration of 0.1 ppm so that the amount of hydroxyl radicals is 2 times more than the amount of moisture, the time required for 99% inactivation is 1 / 2 times, or about 7.5 hours. This inactivation time is inversely proportional to the activation amount (actual hydroxyl radical concentration) of the reaction product of ozone gas and the additive. By controlling the amounts of ozone gas and additive with such an idea, the time until 99% inactivation of the new coronavirus can be estimated. In addition, in the case of using ozone mist formed by mixing ozone gas with water vapor (water particles), a bactericidal rate equivalent to that in the case of using ozone gas from which moisture is removed is shown in about 1 / 5 of the time. In the case where ozone gas is reacted with an alcohol aqueous solution, it is possible to perform sterilization in about 1 / 2 of the time as in the case of using ozone mist, and thus it can be said that the time until inactivation is about 1 / 10 as compared with the case of using ozone gas from which moisture is removed.

[0035] The discharge portion 50 discharges the alcohol aqueous solution as described above by atomizing or vaporizing the alcohol aqueous solution. The alcohol aqueous solution can be discharged by either of atomization or vaporization, or can be discharged by both of atomization and vaporization. In addition, the alcohol aqueous solution can be immediately made into fine droplets after atomization, and then the fine droplets can be vaporized. By atomizing or vaporizing the alcohol aqueous solution, the reaction of ozone gas with the alcohol aqueous solution becomes easily performed, and thus it is possible to efficiently generate hydroxyl radicals. The discharge portion 50 can include at least either of an atomizer that atomizes the alcohol aqueous solution and a vaporizer that vaporizes the alcohol aqueous solution. The atomizer can include, for example, at least one selected from an ultrasonic atomizer, a mesh atomizer, and a compressor atomizer. The vaporizer can include, for example, a heating-type vaporizer.

[0036] The ultrasonic atomizer atomizes the alcohol aqueous solution using a cavitation effect of ultrasonic waves. The ultrasonic atomizer can include an outer tank provided with an ultrasonic vibrator and an inner tank provided at a position more inward than the outer tank. The ultrasonic atomizer, for example, accommodates a coolant such as water in the outer tank in contact with the inner tank, and transmits ultrasonic vibration energy from the ultrasonic vibrator to the alcohol aqueous solution accommodated in the inner tank through the coolant, whereby it is possible to atomize the alcohol aqueous solution.

[0037] A mesh nebulizer sprays an alcohol aqueous solution using ultrasonic vibration and a mesh. The mesh nebulizer can also include an ultrasonic vibrator, a mesh having a plurality of opening portions, and a tank containing an alcohol aqueous solution. The mesh nebulizer extrudes the alcohol aqueous solution in the tank from the plurality of opening portions of the mesh by vibration of the ultrasonic vibrator, for example. Thus, the mesh nebulizer can spray the alcohol aqueous solution.

[0038] A compressor nebulizer sprays an alcohol aqueous solution using gas compressed by a compressor. The compressor nebulizer can include a spray nozzle, a tank, and a compressor. The alcohol aqueous solution contained in the tank is sent to the spray nozzle, and the compressor sends gas such as air to the spray nozzle. The compressor nebulizer can spray the alcohol aqueous solution from the spray nozzle using the gas sent by the compressor.

[0039] A heating-type vaporizer heats an alcohol aqueous solution and discharges the alcohol aqueous solution vaporized by the heating. The heating-type vaporizer can include a heater and a tank storing an alcohol aqueous solution. The heating-type vaporizer can also send the alcohol aqueous solution stored in the tank to the heater and vaporize the sent alcohol aqueous solution by heating. The heater can also heat the alcohol aqueous solution using Joule heat.

[0040] The mole fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less. Hydroxyl radicals can be generated by reacting ozone gas with water, but if an alcohol aqueous solution having a mole fraction within the above range is used, the amount of generated hydroxyl radicals obtained by reacting ozone gas with the alcohol aqueous solution increases. Thus, hydroxyl radicals having higher oxidation power than ozone gas can be generated with high efficiency, and thus the bactericidal and viral inactivation effects can be improved even if the ozone gas concentration in the room is maintained in a low state. The mole fraction of alcohol in the alcohol aqueous solution can be 0.1 or more, or 0.3 or less.

[0041] The alcohol can be discharged in a manner such that the volume ratio with respect to ozone gas is 12 times or less. When the volume ratio is 12 times or less, the amount of generated hydroxyl radicals obtained by reacting ozone gas with the alcohol aqueous solution sometimes increases. The volume ratio can be 11 times or less. In addition, the volume ratio can be 0.1 times or more, 1 times or more, or 2 times or more.

[0042] The alcohol contained in the alcohol aqueous solution is not particularly limited. From the viewpoint of easily atomizing or vaporizing the alcohol aqueous solution, it is preferable to contain an alcohol having 1 or more and 5 or less carbon atoms. The alcohol aqueous solution can include at least one alcohol selected from the group consisting of methanol, ethanol, propanol such as isopropanol, butanol, and pentanol. Among them, the alcohol preferably includes at least any one of ethanol and isopropanol, which are commonly used as disinfecting alcohol. In addition, from the viewpoint that the amount of generated hydroxyl radicals increases, the alcohol preferably includes ethanol.

[0043] In the air purifying system 1 of the present embodiment, ozone gas and the alcohol aqueous solution after atomization or vaporization react on the inner side of the first housing 10. By causing ozone gas and the alcohol aqueous solution to react on the inner side of the first housing 10, a part of the ozone gas disappears on the inner side of the first housing 10. Therefore, even if a large amount of ozone gas is generated, the emission of high-concentration ozone gas into the room can be suppressed. The emission portion 50 may, for example, emit the alcohol aqueous solution into the air flow path 13, or may emit the alcohol aqueous solution into a mixing chamber different from the air flow path 13, and cause ozone gas and the alcohol aqueous solution to react in the air flow path 13 or the mixing chamber. The emission portion 50 can emit the alcohol aqueous solution to a position on the downstream side of the ozone generation portion 40 in the air flow path 13 as shown in FIG. 1, or can emit the alcohol aqueous solution to a position on the upstream side. Figure 1 The emission portion 50 may, for example, emit the alcohol aqueous solution to a position on the downstream side of the ozone generation portion 40 in the air flow path 13 as shown in FIG. 1, or can emit the alcohol aqueous solution to a position on the upstream side.

[0044] The control portion 60 includes a CPU, a ROM, and a RAM. The CPU can read a program stored in the ROM, and execute commands such as operations and controls according to the program. The RAM can store information acquired from the air supply portion 30, the ozone generation portion 40, the emission portion 50, and the like, and the CPU can read the information stored in the RAM and use it for processing such as operations. The control portion 60 can also control the on and off of the driving of the air supply portion 30, the ozone generation portion 40, and the emission portion 50. The control portion 60 can control in such a manner that the air supply portion 30, the ozone generation portion 40, and the emission portion 50 are continuously driven, or can control in such a manner that they are intermittently driven at a prescribed timing. The driving timing of the air supply portion 30, the ozone generation portion 40, and the emission portion 50 can be the same or different. For example, the control portion 60 can control the driving timing of the ozone generation portion 40 and the emission portion 50 in such a manner that the generation of ozone gas and the emission of the alcohol aqueous solution occur at the same time. Alternatively, the control portion 60 can control the driving timing of the ozone generation portion 40 and the emission portion 50 so that the generation of ozone gas and the emission of the alcohol aqueous solution occur at different timings. Further, the control portion 60 can control the driving of the ozone generation portion 40 based on the concentration measured by the ozone concentration sensor.

[0045] Note that, in the present embodiment, an example in which the hydroxyl radical generated by the reaction of the ozone gas generated by the ozone generation portion 40 and the alcohol aqueous solution emitted from the emission portion 50 is emitted from the exhaust port 12 without passing through the ozone decomposition portion or the like is described. However, the air purifying system 1 of the present embodiment purifies air by the hydroxyl radical, and thus can include an ozone decomposition portion that decomposes unreacted ozone gas on the downstream side of the region in the air flow path 13 where the hydroxyl radical is generated. By this, the ozone gas concentration in the room can be reduced while purifying the air. The ozone decomposition portion may, for example, include an ozone decomposition catalyst such as manganese dioxide that decomposes ozone gas by contact with the ozone gas.

[0046] As explained above, the air purification system 1 of the present embodiment is provided with the ozone generating section 40 that generates ozone gas and the discharge section 50 that discharges alcohol aqueous solution that has been atomized or vaporized. The molar fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less. Then, hydroxyl radicals are generated by the reaction of the ozone gas with the alcohol aqueous solution that has been atomized or vaporized.

[0047] Further, the air purification method of the present embodiment includes a process of generating ozone gas, a process of atomizing or vaporizing and discharging alcohol aqueous solution, and a process of generating hydroxyl radicals by the reaction of ozone gas with alcohol aqueous solution that has been atomized or vaporized. The molar fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less.

[0048] The oxidizing power of hydroxyl radicals is higher than that of ozone gas, so even in the case where the concentration of hydroxyl radicals in a space is low, bacteria can be effectively sterilized and viruses can be inactivated. Therefore, it is not necessary to fumigate high-concentration ozone gas in the time when a person is not in a room as in the case of a conventional air purifier. Further, hydroxyl radicals can decompose organic substances by high oxidizing power, so they can be used for deodorization, bleaching, and cleaning, or the like, in place of or in addition to sterilization of bacteria and inactivation of viruses. Therefore, according to the air purification system 1 or the air purification method of the present embodiment, air can be purified by hydroxyl radicals generated by adding an additive to ozone gas. Note that the air purification system 1 or the air purification method can use high-concentration ozone gas in combination with hydrogen radicals in order to improve sterilization of bacteria and inactivation of viruses in the case where a person is not in a room.

[0049] [Second Embodiment]

[0050] Next, the air purification system 1 of the second embodiment will be described. Figure 2 The air purification system 1 of the second embodiment will be described. In the air purification system 1 of the first embodiment, the first housing 10 that houses the ozone generating section 40 and the discharge section 50 is provided, and the ozone gas and the alcohol aqueous solution that has been atomized or vaporized react inside the first housing 10. In the air purification system 1 of the present embodiment, the first housing 10 that houses the ozone generating section 40 and the discharge section 50 is provided, which is the same as the air purification system 1 of the first embodiment. On the other hand, in the air purification system 1 of the present embodiment, the ozone gas and the alcohol aqueous solution that has been atomized or vaporized react outside the first housing 10. The air purification system 1 of the second embodiment is the same as the air purification system 1 of the first embodiment with respect to other points.

[0051] As explained above, the air purification system 1 of the present embodiment is provided with the ozone generating section 40 that generates ozone gas and the discharge section 50 that discharges alcohol aqueous solution that has been atomized or vaporized. The molar fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less. Then, hydroxyl radicals are generated by the reaction of the ozone gas with the alcohol aqueous solution that has been atomized or vaporized. Figure 2As shown, the discharge portion 50 is provided to the first housing 10 in a manner that the aqueous alcohol solution can be discharged to the outside of the first housing 10. The discharge portion 50 discharges the aqueous alcohol solution, for example, toward the ozone gas discharged through the exhaust port 12 of the first housing 10. Thereby, the ozone gas generated by the ozone generation portion 40 and the aqueous alcohol solution discharged from the discharge portion 50 are mixed outside the first housing 10, and the hydroxyl radical is generated.

[0052] As explained above, the air purification system 1 of the present embodiment further includes the first housing 10 that accommodates the ozone generation portion 40 and the discharge portion 50, and the ozone gas and the atomized or vaporized aqueous alcohol solution react outside the first housing 10. According to the air purification system 1 of the present embodiment, since the hydroxyl radical is generated outside the first housing 10, it is possible to contribute to the sterilization or inactivation of bacteria and viruses attached to walls, floors, and ceilings of a room and objects placed in the room.

[0053] [Third Embodiment]

[0054] Next, the air purification system 1 of the third embodiment will be explained. Figure 3 The air purification system 1 of the third embodiment will be explained. In the air purification system 1 of the first embodiment, the first housing 10 that accommodates the ozone generation portion 40 and the discharge portion 50 is provided. On the other hand, the air purification system 1 of the present embodiment includes the second housing 15 that accommodates the ozone generation portion 40 and the third housing 51 that accommodates the discharge portion 50 instead of the first housing 10. Then, the ozone gas and the atomized or vaporized aqueous alcohol solution react outside the second housing 15 and the third housing 51. As to the points other than this, the air purification system 1 of the third embodiment is the same as the air purification system 1 of the first embodiment.

[0055] The air purification system 1 of the present embodiment includes the ozone generation device 3 and the discharge device 4. The ozone generation device 3 includes the second housing 15, the filter portion 20, the air supply portion 30, the ozone generation portion 40, and the control portion 60. The second housing 15 accommodates the filter portion 20, the air supply portion 30, the ozone generation portion 40, and the control portion 60. The second housing 15 corresponds to the first housing 10, and divides the internal space of the ozone generation device 3 and the room space as the external space. As with the first housing 10, the air intake port 11 and the exhaust port 12 are provided to the second housing 15, and the air flow path 13 that connects the air intake port 11 and the exhaust port 12 is provided to the inside of the second housing 15. The ozone generation device 3 is different from the air purification device 2 of the first embodiment in that the discharge portion 50 is not provided, but is the same as the air purification device 2 as to the points other than this. Note that the ozone generation device 3 includes the ozone generation portion 40, and does not necessarily need to include the filter portion 20, the air supply portion 30, and the control portion 60.

[0056] The discharge device 4 includes a discharge portion 50 and a third housing 51. The discharge portion 50 is housed in the third housing 51. The discharge portion 50 is provided to the third housing 51 and sprays the alcohol aqueous solution outside the third housing 51. The discharge portion 50 can be the same as the discharge portion of the first embodiment and atomizes or vaporizes the alcohol aqueous solution to discharge.

[0057] The ozone gas generated by the ozone generating portion 40 is discharged outside the second housing 15. In addition, the discharge device 4 discharges the alcohol aqueous solution outside the third housing 51. Then, the ozone gas generated by the ozone generating portion 40 and the alcohol aqueous solution discharged from the discharge portion 50 are mixed outside the second housing 15 and the third housing 51 to generate hydroxyl radicals.

[0058] As described above, the air purification system 1 of the present embodiment further includes the second housing 15 housing the ozone generating portion 40 and the third housing 51 housing the discharge portion 50. Then, the ozone gas and the alcohol aqueous solution atomized or vaporized react outside the second housing 15 and the third housing 51. According to the air purification system 1 of the present embodiment, the ozone gas and the alcohol aqueous solution react outside the second housing 15 and the third housing 51. Therefore, hydroxyl radicals are generated outside the second housing 15 and the third housing 51, and thus it is possible to contribute to sterilization or inactivation of bacteria and viruses attached to walls, floors, and ceilings in a room and objects placed in the room. In addition, since the second housing 15 housing the ozone generating portion 40 and the third housing 51 housing the discharge portion 50 can be separated, it is possible to make maintenance at the time of failure easy.

[0059] The air purification system 1 is provided in a room of a building, a mobile body, or the like, for example, and can purify air in the room. The air purification system 1 can be used in a house, a hospital, a school, a factory, a smoking room, a car, a bus, a train, a ship, or the like, for example.

[0060] Note that, in the first to third embodiments, a mobile air purification system 1 that can be carried has been described, but the air purification system 1 can also be a stationary air purification system provided to a ceiling or a wall or the like in a room.

[0061] Embodiment

[0062] Hereinafter, the present embodiment will be described in more detail by examples and comparative examples, but the present embodiment is not limited to these examples.

[0063] [Example 1]

[0064] First, a medicine (an additive) of an isopropyl alcohol aqueous solution was prepared by mixing isopropyl alcohol and water at a ratio of 1 : 9 in a manner that the molar fraction of isopropyl alcohol manufactured by Fuji Photo Film Co., Ltd. and light pure drug Co., Ltd. was 0.1. Next, in a manner that the mixture ratio of ozone gas and the isopropyl alcohol aqueous solution after vaporization became ozone : isopropyl alcohol = 1 : 2.8 (volume ratio) or so, the ozone gas and the isopropyl alcohol aqueous solution after vaporization were made to react in a reaction tank. Specifically, the isopropyl alcohol was vaporized by heating the above medicine which was discharged at a flow rate of 20 μL / min in a manner that the volume ratio with respect to the ozone gas was about 2.8 times. More specifically, the above medicine which was discharged at a flow rate of 20 μL / min was heated and vaporized. Then, the medicine after vaporization and the ozone gas having a concentration of 500 ppm and a flow rate of 500 mL / min were mixed, and the reaction was performed in a reaction tank which was kept at 30°C.

[0065] A beaker filled with a chemical sensor liquid was placed in a reaction tank. The chemical sensor liquid was prepared by dissolving terephthalic acid 0.084 g in a mixed liquid of DMF (N,N-dimethylformamide) : methanol = 4 : 1 250 mL in a manner that the concentration of terephthalic acid became 2 mmol / L. Terephthalic acid was manufactured by Fuji Photo Film Co., Ltd. and light pure drug Co., Ltd. as a special grade, DMF was manufactured by Fuji Photo Film Co., Ltd. and light pure drug Co., Ltd. as a special grade, and methanol was manufactured by Fuji Photo Film Co., Ltd. and light pure drug Co., Ltd. as a special grade.

[0066] Terephthalic acid does not emit fluorescence even if ultraviolet rays of a wavelength of 310 nm are irradiated. However, 2-hydroxyterephthalic acid which is generated by the reaction of terephthalic acid with hydroxyl radicals absorbs ultraviolet rays of a wavelength of 310 nm and emits fluorescence having a peak near a wavelength of 425 nm. Therefore, the chemical sensor liquid was used as an index of the amount of generation of hydroxyl radicals. The fluorescence intensity of the chemical sensor liquid was measured using a spectrofluorophotometer RF-5300 manufactured by Shimadzu Corporation. Specifically, the chemical sensor liquid was irradiated with ultraviolet rays of a wavelength of 310 nm, and the peak intensity of the spectrum of the fluorescence emitted from the chemical sensor liquid near a wavelength of 425 nm (hydroxyl radical fluorescence peak height) was measured.

[0067] [Example 2]

[0068] A medicine of an isopropyl alcohol aqueous solution was prepared by mixing isopropyl alcohol and water at a ratio of 3 : 7 in a manner that the molar fraction of isopropyl alcohol became 0.3, and the hydroxyl radical fluorescence peak height was measured in the same manner as in Example 1. Note that the isopropyl alcohol was vaporized in a manner that the volume ratio with respect to the ozone gas was about 8.1 times.

[0069] [Example 3]

[0070] A reagent of an ethanol aqueous solution was prepared by mixing ethanol and water in a ratio of 1 :9 in a manner that the molar fraction of the ethanol manufactured by Fuji Photo Film Co., Ltd. and Gokyo Co., Ltd. became 0.1, and the hydroxyl radical fluorescence peak height was measured in the same manner as in Example 1, except for this. Note that the ethanol was emitted in a manner that it was about 3.6 times by volume relative to the ozone gas, in terms of gas.

[0071] [Example 4]

[0072] A reagent of an ethanol aqueous solution was prepared by mixing ethanol and water in a ratio of 3 :7 in a manner that the molar fraction of the ethanol became 0.3, and the hydroxyl radical fluorescence peak height was measured in the same manner as in Example 1, except for this. Note that the ethanol was emitted in a manner that it was about 11 times by volume relative to the ozone gas, in terms of gas.

[0073] [Comparative Example 1]

[0074] The hydroxyl radical fluorescence peak height was measured in the same manner as in Example 1, except for using water having a molar fraction of alcohol of 0 as a reagent.

[0075] [Comparative Example 2]

[0076] A reagent of an isopropyl alcohol aqueous solution was prepared by mixing isopropyl alcohol and water in a ratio of 1 : 1 in a manner that the molar fraction of the isopropyl alcohol became 0.5, and the hydroxyl radical fluorescence peak height was measured in the same manner as in Example 1, except for this. Note that the isopropyl alcohol was emitted in a manner that it was about 13 times by volume relative to the ozone gas, in terms of gas.

[0077] [Comparative Example 3]

[0078] A reagent of an ethanol aqueous solution was prepared by mixing ethanol and water in a ratio of 1 : 1 in a manner that the molar fraction of the ethanol became 0.5, and the hydroxyl radical fluorescence peak height was measured in the same manner as in Example 1, except for this. Note that the ethanol was emitted in a manner that it was about 19 times by volume relative to the ozone gas, in terms of gas.

[0079] [Table 1]

[0080] Pharmaceutical agent Hydroxyl radical fluorescence peak height (A.U.) Volume ratio of alcohol Example 1 Isopropanol aqueous solution (mole fraction 0.1) 101 2.8 Example 2 Isopropanol aqueous solution (mole fraction 0.3) 88 8.1 Example 3 Ethanol aqueous solution (mole fraction 0.1) 127 3.6 Example 4 Ethanol aqueous solution (mole fraction 0.3) 125 11 Comparative Example 1 Water (mole fraction 0) 67 0 Comparative Example 2 Isopropanol aqueous solution (mole fraction 0.5) 46 13 Comparative Example 3 Ethanol aqueous solution (mole fraction 0.5) 75 19

[0081] As shown in Table 1 and Figure 4 , in Example 1 to Example 4, an alcohol aqueous solution having a molar fraction of 0.05 or more and 0.35 or less was reacted with ozone gas. Note that in Figure 4A line of +5% and -5% as a measurement error of the fluorescence peak height of hydroxyl radicals was added to the middle. In these examples, the amount of generation of hydroxyl radicals increased compared to the case where water and an alcohol aqueous solution with a mole fraction of 0.5 were reacted with ozone gas like in Comparative Examples 1 to 3. For example, in the case of an ethanol aqueous solution (mole fraction 0.1), the peak value of hydroxyl radicals was 1.9 times compared to the case of water, and had about 2 times the activity (bactericidal performance). The mechanism is not certain, but can be inferred from the reactivity of ozone gas. First, if moisture is present, it is easy to react with ozone gas to generate hydroxyl radicals.

[0082] Since the reactivity of ozone gas is higher with alcohol than with water, it is considered that in the case where an alcohol aqueous solution like in Examples 1 to 4 is reacted, the amount of generation of hydroxyl radicals is about 2 times more than in the case where water is reacted. On the other hand, if the mole fraction of alcohol is too much, the generated hydroxyl radicals react with alcohol, and part of the generation of hydroxyl radicals disappears. Therefore, in the case where the mole fraction is 0.5, it is inferred that the amount of generation of hydroxyl radicals decreases. Note that in this example, the amount of generation of hydroxyl radicals was evaluated at a concentration of ozone gas of 500 ppm for the convenience of the device, but the same result can be expected in a system at a low concentration of ozone gas of 0.1 ppm or the like.

[0083] In addition, the volume ratio of alcohol to ozone gas (alcohol volume ratio) after vaporization was observed, and was 2.8 in Example 1 where the mole fraction of alcohol after the concentration of hydroxyl radicals increased was 0.1, and was 3.6 in Example 3. In addition, it was 8.1 in Example 2 where the mole fraction of alcohol was 0.3, and was 11 in Example 4. Therefore, the volume ratio of the amount of addition of alcohol to ozone gas reaches 12 times in the case of conversion to gas, and is a preferable range.

[0084] The entire contents of Japanese Patent Application No. 2020-189387 (Filing date: November 13, 2020) are hereby incorporated by reference.

[0085] Several embodiments have been described, but modifications or variations of the embodiments can be made based on the above disclosure. All the constituent elements of the above embodiments and all the features recited in the claims can also be extracted and combined, respectively, as long as they do not contradict each other.

[0086] The present disclosure can contribute, for example, to Goal 3 of the United Nations-led Sustainable Development Goals (SDGs), “Ensure healthy lives and promote well-being for all at all ages”.

[0087] Explanation of symbols

[0088] 1…air purification system, 10…first housing, 15…second housing, 40…ozone generating section, 50…discharge section, 51…third housing.

Claims

1. An air purification system comprising: an ozone generating section that generates ozone gas; and a discharge section that discharges an alcohol aqueous solution that has been atomized or vaporized, wherein a mole fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less, and wherein hydroxyl radicals are generated by a reaction of the ozone gas with the alcohol aqueous solution that has been atomized or vaporized. The alcohol includes at least any one of ethanol and isopropyl alcohol. The alcohol is discharged in a manner that a volume ratio with respect to the ozone gas is 12 times or less when converted into a gas.

2. The air purification system of claim 1, wherein, Further comprising a first housing that accommodates the ozone generating section and the discharge section, 3. The air purification system of claim 1 or 2, wherein, The ozone gas and the alcohol aqueous solution that has been atomized or vaporized react on an inside of the first housing.

4. The air purification system of claim 1 or 2, wherein, Further comprising a first housing that accommodates the ozone generating section and the discharge section, The ozone gas and the alcohol aqueous solution that has been atomized or vaporized react on an outside of the first housing.

5. The air purification system of claim 1 or 2, wherein, Further comprising a second housing that accommodates the ozone generating section and a third housing that accommodates the discharge section, The ozone gas and the alcohol aqueous solution that has been atomized or vaporized react on an outside of the second housing and the third housing.

6. The air purification system of claim 1 or 2, wherein, An ozone gas concentration in an outside space is controlled to be 0.1 ppm or less.

8. An air purification method comprising:

7. The air purification system of claim 1 or 2, wherein, a process of generating ozone gas, a process of discharging an alcohol aqueous solution that has been atomized or vaporized, and a process of generating hydroxyl radicals by a reaction of the ozone gas with the alcohol aqueous solution that has been atomized or vaporized; a mole fraction of alcohol contained in the alcohol aqueous solution with respect to the alcohol aqueous solution is 0.05 or more and 0.35 or less. ​ ​

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