Carbon dioxide nanobubble water or carbon dioxide nanobubble mist, and method for producing the same

Abstract

To provide a carbon dioxide nanobubble water or a carbon dioxide nanobubble mist capable of using as a bactericidal agent for an intended purpose by significantly generating a hydroxyl radical having sterilization capability without using a chemical liquid and a chemosynthesis preparation.SOLUTION: A carbon dioxide nanobubble water or a carbon dioxide nanobubble mist used for sterilization has a peak particle diameter of a contained carbon dioxide nanobubble of 100 nm or less, a dissolved carbon dioxide amount of 2,000 mg / L or more and a nanobubble concentration of 6 to 8×107 particles / mL during generation of nanobubbles, and a half-life time of a nanobubble concentration of 300 hours or more after the generation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to carbon dioxide nanobubble water or carbon dioxide nanobubble mist used for sterilization, and a method for producing the same.

Background Art

[0002] In recent years, as environmentally friendly activities such as SDGs have spread globally, the number of consumers aiming for so-called "weigh-and-sell" has been increasing for alcoholic beverages, various drinks, milk, lotion, etc. for the purpose of reducing waste containers.

[0003] Such weigh-and-sell is a sales method in which stores fill alcoholic beverages, various drinks, milk, lotion, etc. provided by the store into containers brought by consumers themselves. However, there is a problem of how to clean and sterilize the inside of the brought containers safely and securely to fill the contents.

[0004] Also, at home, sterilization (disinfection) of baby bottles and food and beverage storage containers is essential. However, general hot water disinfection takes time and also involves risks such as burns.

[0005] Furthermore, due to the global pandemic of the novel coronavirus, sterilization of indoor spaces (general households, workplaces, stores, medical sites, etc.) is required. However, in the daily living environment, it is desirable to perform cleaning, sterilization, and disinfection without using chemical solutions that may be harmful to health as much as possible. Although sterilization with hypochlorous acid, etc. is simple and does not use electricity, and the sterilization effect is also effective, there are problems such as concerns about adverse effects on the human body.

[0006] As other sterilization methods that do not use chemical solutions, there is the ultraviolet sterilization method, etc. However, ultraviolet rays with a short wavelength are harmful to the human body. Therefore, an ultraviolet light source with a slightly longer wavelength called a black light has come to be used for sterilization, but there is a problem that the sterilization effect by ultraviolet irradiation is limited.

[0007] In addition, various studies have shown that nanobubbles have a sterilizing effect, and in particular, a sterilization method using ozone nanobubble water has also been put into practical use. However, issues such as the need for caution in handling ozone remain.

[0008] On the other hand, Patent Document 1 (Japanese Patent Application Laid-Open No. 2009-131770), Patent Document 2 (Japanese Patent Application Laid-Open No. 2011-088842), and Patent Document 3 (Japanese Patent Application Laid-Open No. 2020-171263) disclose inventions that use carbon dioxide nanobubbles for sterilization instead of ozone, etc. However, the specific sterilization effect, the duration of the sterilization action, the utilization method, etc. are not clear, and there are doubts about the effectiveness.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] As disclosed in the inventions related to the above patent applications, it has been determined to some extent that carbon dioxide nanobubble water has a sterilizing effect, but the carbon dioxide nanobubbles themselves do not have a sterilizing ability. According to the research of the inventors of the present application, it has been found that the sterilizing effect observed in carbon dioxide nanobubble water is mainly due to the hydroxyl radicals generated by carbon dioxide nanobubble water.

[0011] Although the internal pressure of nanobubbles can reach several tens of atmospheres, the interface of carbon dioxide nanobubbles is softer compared to that of nanobubbles composed of nitrogen and oxygen. Therefore, the carbon dioxide encapsulated in carbon dioxide nanobubbles is more likely to jet out to the outside compared to nitrogen nanobubbles, oxygen nanobubbles, etc. Also, since the internal pressure of nanobubbles increases as the particle size decreases, the smaller the particle size of carbon dioxide nanobubbles, the easier it is for the encapsulated carbon dioxide to jet out to the outside, and as a result, a large amount of hydroxyl radicals will be generated.

[0012] That is, the fact revealed by the research of the present inventors is that the amount and significance of generating hydroxyl radicals having sterilization ability by carbon dioxide nanobubble water determines the sterilization action and sterilization effect (sterilization ability). In this specification, the ability to sterilize bacteria including Escherichia coli, Staphylococcus aureus, and periodontal pathogens to 1 / 100 or less within 30 minutes is defined as a significant sterilization ability.

[0013] The present invention responds to the era when it is desirable to effectively sterilize fungi existing inside containers or fungi existing in various indoor environmental air in a simple and safe manner even in retail stores and households by significantly generating hydroxyl radicals having sterilization ability, and from the viewpoints of the progress of a sustainable society and consideration for the environment, it provides carbon dioxide nanobubble water or carbon dioxide nanobubble mist that can be used as a bactericide according to the purpose of use without using chemical solutions or chemically synthesized preparations.

[0014] To achieve the above object, the present invention is carbon dioxide nanobubble water or carbon dioxide nanobubble mist used for sterilization, wherein the peak particle diameter in the particle size distribution of the contained carbon dioxide nanobubbles is 100 nm or less, the dissolved carbon dioxide amount at the time of nanobubble generation is 2000 mg / L or more, the nanobubble concentration is 6 - 8×10 7 particles / mL, and the time for the nanobubble concentration to be halved is 300 hours or more after generation, which is characterized by this.

[0015] The present invention also relates to a method for producing the above carbon dioxide nanobubble water, comprising a carbon dioxide gas cylinder, a gas injector, a production container, and a piezoelectric vibrator. (Step 1) Carbon dioxide gas filled in the carbon dioxide gas cylinder is bubbled into the water filled in the production container by the gas injector so that the dissolved carbon dioxide amount becomes 2×10 3 mg / L or more. (Step 2) The water after bubbling is vibrated by the piezoelectric vibrator at a vibration frequency of 1 to 2 MHz for 50 to 60 minutes. This is the gist of the invention.

[0016] Furthermore, the present invention relates to a method for producing the above carbon dioxide nanobubble mist, comprising a carbon dioxide gas cylinder, a gas injector, a production container, a piezoelectric vibrator, a fan for discharging the carbon dioxide nanobubble water to the outside as mist, and an injection cylinder. (Step 1) Carbon dioxide gas filled in the carbon dioxide gas cylinder is bubbled into the water filled in the production container by the gas injector so that the dissolved carbon dioxide amount becomes 2×10 3 mg / L or more. (Step 2) The water after bubbling is vibrated by the piezoelectric vibrator at a vibration frequency of 1 to 2 MHz for 50 to 60 minutes to produce carbon dioxide nanobubble water. (Step 3) Wind is blown by the fan onto the carbon dioxide nanobubble mist rising on the liquid surface of the produced carbon dioxide nanobubble water, and the carbon dioxide nanobubble mist is discharged to the outside of the production container from the injection cylinder. This is the gist of the invention.

Advantages of the Invention

[0017] According to the carbon dioxide nanobubble water or carbon dioxide nanobubble mist of the present invention having the above configuration, bacteria such as Escherichia coli, Staphylococcus aureus, and periodontal bacteria can be sterilized to 1 / 100 or less within 30 minutes (according to the fair competition rules and enforcement regulations determined by the Detergent and Soap Fair Trade Council). It has a sterilizing effect and can be used as a simple and inexpensive disinfectant without using a chemical solution harmful to the human body. Moreover, once the carbon dioxide nanobubble water is produced, it can maintain the sterilizing effect for 300 hours or more, making it possible to prepare it in advance.

[0018] In addition, since the carbon dioxide nanobubble water or carbon dioxide nanobubble mist of the present invention can be produced using a simple and inexpensive device, it can be purchased and used at a reasonable price even at grocery stores or in ordinary households.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a conceptual diagram of an apparatus for generating carbon dioxide nano-bubble water and carbon dioxide nano-bubble mist according to the invention of the present application. The generating apparatus 1 is composed of a water supply tank 2, a carbon dioxide gas cylinder 3, a gas injector 3-1, a generating container 4, a piezoelectric vibrator 5, a fan 6 for discharging the carbon dioxide nano-bubble water to the outside of the generating container 4 as mist, and an injection cylinder 7. When only generating carbon dioxide nano-bubble water, the fan 6 and the injection cylinder 7 for atomizing and discharging are not necessary. Hereinafter, nano-bubbles may be abbreviated as "NB", and carbon dioxide may also be referred to as "carbon dioxide gas".

[0021] In this example, pure water was used as the sample, a commercially available SODASTREAM (registered trademark) was used for the carbon dioxide gas cylinder 3, and a commercially available "IM1-24-PS1" (manufactured by SEIKO GIKEN Inc.) was used for the piezoelectric vibrator 5. The water used is not limited to pure water, and may be tap water or mineral water.

[0022] The surface of the piezoelectric vibrator 5 was coated with a glass material, and the driving ultrasonic frequency was 1.7 MHz. As the generating container 4, an aluminum one with a capacity of 200 mL (inner diameter 50 mm) was used. The piezoelectric vibrator 5 was installed at the bottom of the generating container 4, and the generating container 4 was installed on a cooling plate driven by a Peltier element to maintain the temperature at 20°C or lower.

[0023] The initial dissolved oxygen in pure water was 8.1 mg / L, and the dissolved carbon dioxide was 0.26 mg / L. In order to increase the dissolved carbon dioxide concentration, the carbon dioxide gas filled in the carbon dioxide gas cylinder 3 was bubbled by the gas injector 3-1. The dissolved carbon dioxide after bubbling was 3.5×10 3 mg / L.

[0024] The carbonated water in the generating container 4 after bubbling was irradiated with ultrasonic waves of 1.7 MHz by the piezoelectric vibrator 5. The irradiation time was 1 hour. The amount of dissolved carbon dioxide after 1 hour of irradiation decreased to 35 mg / L, and the NB concentration was 7×10 7It was [X] particles / mL. The carbon dioxide reduced by ultrasonic irradiation is presumably trapped in the NB.

[0025] Figure 2 is a graph showing the particle size distribution (particle size dispersion) of the carbon dioxide NB generated by the above method. As shown in Figure 2, the particle size of the carbon dioxide NB is distributed from 50 to 150 nm, and the peak particle size of the particle size distribution is about 70 nm. As described above, the smaller the particle size of the carbon dioxide NB, the easier the encapsulated carbon dioxide is to eject to the outside, and as a result, a large amount of hydroxyl radicals will be generated. The optimal particle size is 70 to 80 nm, and it is desirable to generate carbon dioxide NB with this particle size as the peak of the distribution. Note that Figure 10 is a graph measuring the relationship between the ultrasonic irradiation time and the average particle size of the carbon dioxide NB. Up to about 60 minutes, the average particle size decreases rapidly, but after exceeding 100 minutes, the coalescence of the NB progresses and it becomes larger instead. Therefore, the ultrasonic irradiation time is optimally about 50 to 60 minutes.

[0026] In the present invention, ultrasonic waves are irradiated to carbonated water to generate carbon dioxide NB. Since the dissolved carbon dioxide is trapped in the NB, the NB concentration increases in proportion to the ultrasonic irradiation time.

[0027] Figure 3 is a graph showing the results of measuring the irradiation time dependence of the carbon dioxide NB concentration. When the ultrasonic irradiation is continued, the concentration of the carbon dioxide NB increases, but the concentration after 1 hour of irradiation increased rapidly to 7×10 7 particles / mL. After that, when the irradiation was continued, the rate of increase in the concentration of the carbon dioxide NB became slower.

[0028] As one method of further increasing the concentration of carbon dioxide NB, a method of re-bubbling carbon dioxide gas at regular intervals (for example, every 1 hour) can be considered. However, when the concentration of carbon dioxide NB increases, the combination of carbon dioxide NB progresses, the particle size of carbon dioxide NB gradually increases, and accordingly, the concentration of carbon dioxide NB with a small particle size decreases. Furthermore, it is considered that the particle size enlargement occurs by irradiating the generated carbon dioxide NB with ultrasonic waves, and as a result, the carbon dioxide NB concentration decreases. Therefore, the optimal concentration of carbon dioxide NB from the viewpoint of the sterilization effect is 7×10 7 particles / mL or so.

[0029] Figure 4 is a graph and a photograph showing the verification results regarding the sterilization effect exerted by the generated carbon dioxide NB water. Escherichia coli was used for this verification. The photograph in Figure 4 shows the change in the colony form on the petri film after holding Escherichia coli in carbon dioxide NB water for 15 minutes, and it can be seen that the number of colonies decreased (died) significantly in an extremely short time. Figure 4 also shows a graph of the time change in the survival rate of Escherichia coli in NB water. This time change can be expressed as (survival rate) ∝ EXP(-kt) (t is time), and the coefficient k NB of the exponential part is here called the sterilization ability of nanobubbles (the unit is min -1 ). The larger this value, the greater the sterilization ability. The result of Figure 4 is k NB = 0.32 (min -1 ), and the time when the number of bacteria becomes 1 / 100 is about 14 minutes. The ability to kill Escherichia coli is equivalent to that for Staphylococcus aureus, periodontal pathogens, etc.

[0030] In the graph of Figure 4, for comparison with the present invention, the result of leaving Escherichia coli in pure water is indicated by ○. Even in pure water, the survival rate of Escherichia coli gradually decreases with time, but this decrease in the survival rate is due to the inactivation of Escherichia coli in degassed pure water due to lack of nutrients and oxygen, and does not show a sterilization effect by pure water.

[0031] Figure 5 is a graph and a photograph verifying the sterilization effect of carbon dioxide NB water in a mistified state according to the invention of the present application. The photograph in Figure 5 shows the change in the colony morphology on the petri film after holding Escherichia coli in carbon dioxide NB water for 15 minutes, similar to Figure 4. It can be seen that the number of colonies decreased (died) significantly in an extremely short time. According to this verification, it was shown that there is a sterilization effect equivalent to that of the liquid not only in the liquid state but also in the mistified state. When using carbon dioxide NB water as a disinfectant, if it can be used in a mistified state, its scope of use can be greatly expanded as a disinfectant for the inside of containers with complex shapes and indoor spaces.

[0032] In widely using and applying carbon dioxide NB water as a disinfectant, the persistence of the sterilization effect (sterilization life) is a very important aspect. Even if carbon dioxide NB water with a high sterilization effect can be generated, if it is lost within about a few minutes, its utility value will be extremely small.

[0033] Figure 6 is a graph showing the change in NB concentration of carbon dioxide NB water over time according to the invention of the present application. The NB concentration of carbon dioxide NB water and the sterilization effect are in a proportional relationship as will be described later. However, even after 300 hours have passed since generation, the concentration has only decreased by about half and still maintains a high concentration. The life of NB is proportional to the particle size because the smaller the particle size, the smaller the probability of coalescence.

[0034] Figure 7 is a graph and a photograph showing the results of examining the sterilization effect of carbon dioxide NB water one week after generation. The sterilization effect (sterilization ability) was k NB = 0.16 min -1 The photograph in Figure 7 shows the change in the colony morphology on the petri film after holding Escherichia coli in carbon dioxide NB water for 15 minutes, similar to Figure 4. It can be seen that the number of colonies decreased (died) significantly in a short time. Although the sterilization effect has decreased slightly compared to immediately after the generation of carbon dioxide NB water, it can be seen that it still maintains a strong sterilization effect. The fact that the time for maintaining the sterilization effect is long enables pre-production and is extremely advantageous for application to actual products.

[0035] Figure 8 is a graph showing the correlation between carbon dioxide NB concentration and sterilization action, and the sterilization action of carbon dioxide NB becomes stronger as the concentration of carbon dioxide NB increases. When comparing the sterilization action of NB water obtained by irradiating pure water with ultrasound and carbon dioxide NB water obtained by irradiating carbonated water with carbon dioxide bubbling with ultrasound, it is found that there is an overwhelming difference of more than 10 times at the same NB concentration. The NB generated when pure water is irradiated with ultrasound is dissolved air, and since most of it is nitrogen, the interface is hard, it is difficult to eject to the outside, and there is little generation of hydroxyl radicals.

[0036] In order to investigate the factor (cause) of the sterilization effect of carbon dioxide NB water generated by irradiating carbonated water with ultrasound, radical species in the carbon dioxide NB water were detected using ESR.

[0037] Figure 9 is a graph plotting typical ESR spectra of the carbon dioxide NB water (Soda-SNB) according to the present invention, pure water NB water (SNB) in which NB is generated by irradiating pure water with ultrasound, and simple carbonated water (Soda), with (a) showing the ESR spectrum of carbon dioxide NB water (Soda-SNB), (b) showing the ESR spectrum of pure water NB water (SNB), and (c) showing the ESR spectrum of carbonated water (Soda). The peaks indicated by ● in the figure are due to hydroxyl radicals (·OH), which have strong bactericidal properties, and although hydroxyl radicals can be confirmed in pure water NB water and carbonated water, the amount is far less than that in carbon dioxide NB water.

[0038] As shown in Fig. 9, the NB concentration in the pure NB water is sufficiently high (4 × 10 7 Despite the fact that the concentration of hydroxyl radicals in the carbonated water was 100% (particles / mL), almost no disinfecting effect was observed. The amount of hydroxyl radicals in the carbonated water was also extremely small, indicating that dissolved carbon dioxide alone does not have a disinfecting effect. From this, it can be concluded that the disinfecting effect of the carbon dioxide NB water is due to the disinfecting ability of the hydroxyl radicals generated by the carbon dioxide NB water.

[0039] Carbon dioxide NB water produces significantly more reactive oxygen species than NB water produced from pure water alone. The reaction involved in the formation of reactive oxygen species is thought to occur between the solutes present in the NB water and NB. The solubility of carbon dioxide in water is about three orders of magnitude higher than that of oxygen and nitrogen. Carbon dioxide has a strong interaction with water molecules, and it is considered that the carbon dioxide molecules encapsulated in NB react with the water molecules at the NB interface, making the NB interface structurally unstable.

[0040] As described above, the present inventors proposed that the interface of NB has a two-dimensional interfacial layer composed of water molecule clusters, and clarified that carbon dioxide molecules interact with the interfacial water molecule clusters to soften the interface. It can be interpreted that NB with a softened interface is more likely to react with solute molecules and bacteria around it, and is more likely to generate radicals.

[0041] On the other hand, oxygen and nitrogen hardly interact with the interfacial water clusters, and the interface is harder than in the case of carbon dioxide. Therefore, it can be interpreted that these gas molecules are less likely to generate reactive oxygen species and the antibacterial ability against Escherichia coli etc. does not increase.

[0042] Furthermore, since the internal pressure of NB with a size of 100 nm or less is estimated to be several tens of atmospheres or more, the high-pressure encapsulated carbon dioxide promotes the radical generation reaction. Since the peak particle size in the particle size distribution of the carbon dioxide NB produced in the present invention is 100 nm or less, the high internal pressure promotes radical generation.

[0043] In the above-described example, the dissolved carbon dioxide after bubbling with the carbon dioxide gas cylinder 3 was set to 3.5×10 3 mg / L, but it may be 2×10 3 mg / L or more.

[0044] Also, the vibration frequency by the piezoelectric vibrator 5 was set to 1.7 MHz, but it may be 1 to 2 MHz, and the ultrasonic irradiation time was set to 1 hour, but it may be 1 hour or more. Furthermore, the NB concentration was set to 7×10 7 particles / mL, but it may be 6 to 8×10 7It is sufficient if it is at the level of particles / mL.

[0045] In addition, in the above embodiment, the condition of the water temperature for generating carbon dioxide NB was described as 20°C or lower, but it may be 40°C or lower.

[0046] As described above, the carbon dioxide nanobubble water or carbon dioxide nanobubble mist according to the present invention has a significant bactericidal effect of sterilizing bacteria including Escherichia coli, Staphylococcus aureus, and periodontal bacteria to 1 / 100 or less within 30 minutes, and can be utilized for any articles and environments (including dental treatment, etc.) that require sterilization. In particular, since the mist also exhibits a significant bactericidal effect, it can also be utilized for sterilization inside containers having a complex shape and for indoor environment sterilization using a humidifier or the like.

[0047] In addition, the carbon dioxide nanobubble water or carbon dioxide nanobubble mist according to the present invention can be generated by an extremely simple and inexpensive device, and can be generated not only with pure water but also with tap water or commercially available mineral water, and can be prepared in advance. Therefore, the running cost required for generation can be extremely low, and it can be used inexpensively and easily even in small-scale stores and ordinary households.

Explanation of Signs

[0048] 1 Generation device 2 Water supply tank 3 Carbon dioxide gas cylinder 3-1 Gas injection nozzle 4 Generation container 5 Piezoelectric vibrator 6 Fan 7 Injection cylinder

Claims

1. Carbon dioxide nanobubble water or carbon dioxide nanobubble mist used for sterilization, wherein the peak particle size in the particle size distribution of the contained carbon dioxide nanobubbles is 100 nm or less, The amount of dissolved carbon dioxide during nanobubble generation is 2000 mg / L or more, and the nanobubble concentration is 6 to 8×10 ７ particles / mL, and the time for the nanobubble concentration to halve is 300 hours or more after generation, carbon dioxide nanobubble water or carbon dioxide nanobubble mist, characterized by the above.

2. The peak particle size of the carbon dioxide nanobubbles is 70 to 80 nm, carbon dioxide nanobubble water or carbon dioxide nanobubble mist according to Claim 1, characterized by the above.

3. A method for producing carbon dioxide nanobubble water according to Claim 1 or 2, comprising a carbon dioxide gas cylinder, a gas injector, a generation container, and a piezoelectric vibrator, (Step 1) To the water filled in the production container, carbon dioxide gas filled in the carbon dioxide gas cylinder is bubbled by the gas injector so that the dissolved carbon dioxide amount becomes 2 × 10 ３ mg / L or more. (Step 2) vibrating the water after bubbling with the piezoelectric vibrator at a frequency of 1 to 2 MHz for 50 to 60 minutes, a method for producing carbon dioxide nanobubble water, characterized by the above.

4. The water is any one of tap water, mineral water, and pure water, a method for producing carbon dioxide nanobubble water according to Claim 3, characterized by the above.

5. A method for producing carbon dioxide nanobubble mist according to Claim 1 or 2, comprising a carbon dioxide gas cylinder, a gas injector, a generation container, a piezoelectric vibrator, a fan for discharging the carbon dioxide nanobubble water as mist to the outside, and an injection cylinder, (Step 1) To the water filled in the production container, carbon dioxide gas filled in the carbon dioxide gas cylinder is bubbled by the gas injector so that the dissolved carbon dioxide amount becomes 2 × 10 ３ mg / L or more, (Step 2) vibrating the water after bubbling with the piezoelectric vibrator at a frequency of 1 to 2 MHz for 50 to 60 minutes to generate carbon dioxide nanobubble water, (Step 3) blowing air by the fan onto the carbon dioxide nanobubble mist rising on the liquid surface of the generated carbon dioxide nanobubble water, and discharging the carbon dioxide nanobubble mist from the injection cylinder to the outside of the generation container, a method for producing carbon dioxide nanobubble mist, characterized by the above.

6. The water is any one of tap water, mineral water, and pure water, a method for producing carbon dioxide nanobubble mist according to Claim 5, characterized by the above.

Images