JP7528405B2 - Atmospheric pressure low temperature plasma bubble liquid - Google Patents

Description

The present invention relates to an atmospheric pressure low-temperature plasma bubble liquid, which contains atmospheric pressure low-temperature plasma-containing gas obtained by converting a specific raw material gas into plasma under specific conditions in the form of fine bubbles in the liquid.
The present invention also relates to a method for producing an atmospheric pressure low-temperature plasma bubble liquid, in which atmospheric pressure low-temperature plasma-containing gas obtained by plasmatizing a specific raw material gas under specific conditions is added to a liquid as fine bubbles using a bubble generator.
Furthermore, the present invention relates to an atmospheric pressure low-temperature plasma bubble liquid manufacturing apparatus comprising at least a plasma-containing gas manufacturing machine that produces atmospheric pressure low-temperature plasma-containing gas by plasmatizing a specific raw material gas under specific conditions, a plasma-containing gas transport path that maintains the temperature of the plasma-containing gas at -25 to 100°C, and a bubble generator.

Liquids containing fine bubbles having a diameter of less than 1 mm have attracted attention in a wide variety of fields because of the various functions that are attributable to the fine bubbles, and are known to have a wide variety of applications.
It is also known to use plasma containing gases in a wide variety of applications.
Patent documents 1 to 5 describe plasma bubble liquids that contain plasma-containing gas in the form of fine bubbles in the liquid and have sterilizing and cleaning functions.

However, these patent documents do not state or suggest the formation of a plasma bubble liquid using fine bubbles made from "atmospheric pressure low-temperature plasma-containing gas at a temperature of -25 to 100°C obtained by plasmatizing at least one raw material gas selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor under conditions of a pressure of 0.1 to 10 atmospheres, a raw material gas supply rate of 0.001 to 100,000 L/min, and an electric field strength of 1 to 1,000 kV/cm."

JP 2006-88115 A JP 2008-178870 A JP 2012-228644 A International Publication No. 2015/072461 JP 2016-203082 A

The problem to be solved by the present invention is to provide an atmospheric pressure low-temperature plasma bubble liquid that has excellent pollutant decomposition (cleaning) and sterilization functions.
Another object of the present invention is to provide a method for producing an atmospheric pressure low-temperature plasma bubble liquid that has excellent pollutant decomposition (cleaning) and sterilization functions.
Furthermore, the present invention aims to provide an apparatus for producing atmospheric pressure low-temperature plasma bubble liquid that has excellent functions such as decomposing pollutants (cleaning function) and sterilizing functions.

As a result of extensive investigations aimed at solving the above problems, the present inventors have completed the following invention.
[1] A method for producing a raw material gas, which is at least one selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor, comprising:
Pressure: 0.1 to 10 atmospheres
A raw material gas supply rate of 0.001 to 100,000 L/min and an electric field strength of 1 to 1,000 kV/cm;
The atmospheric pressure low-temperature plasma bubble liquid is obtained by adding atmospheric pressure low-temperature plasma-containing gas having a temperature of -25 to 100°C obtained by plasmatizing the gas under the above conditions into a liquid as fine bubbles.
[2] The atmospheric pressure low-temperature plasma bubble liquid according to [1], wherein the temperature is −25 to 40° C.
[3] A method for producing a raw material gas, which is at least one selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor, comprising:
Pressure: 0.1 to 10 atmospheres
A raw material gas supply rate of 0.001 to 100,000 L/min and an electric field strength of 1 to 1,000 kV/cm;
The atmospheric pressure low-temperature plasma-containing gas having a temperature of -25 to 100°C obtained by plasmatizing the gas under the above conditions is added to the liquid as fine bubbles using a bubble generator.
[4] A method for producing a raw material gas, which is at least one selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor, comprising:
Pressure: 0.1 to 10 atmospheres
A raw material gas supply rate of 0.001 to 100,000 L/min and an electric field strength of 1 to 1,000 kV/cm;
The atmospheric pressure low-temperature plasma bubble liquid producing device comprises at least a plasma-containing gas producing machine for producing atmospheric pressure low-temperature plasma-containing gas at a temperature of -25 to 100°C by plasmatizing the liquid under the above conditions, and a bubble generator.

According to the present invention, there is provided an atmospheric pressure low-temperature plasma bubble liquid having excellent pollutant decomposition (cleaning) and sterilization functions.
In addition, a method for producing atmospheric pressure low-temperature plasma bubble liquid that has excellent pollutant decomposition (cleaning) and sterilization functions is provided.
Furthermore, an apparatus for producing atmospheric pressure low-temperature plasma bubble liquid having excellent pollutant decomposition (cleaning) and sterilization functions is provided.

[Atmospheric pressure low-temperature plasma bubble liquid]
The atmospheric pressure low-temperature plasma bubble liquid of the present invention contains atmospheric pressure low-temperature plasma-containing gas obtained by plasmatizing a specific raw material gas under specific conditions in the form of one or more fine bubbles selected from the group consisting of nanobubbles, fine bubbles, and microbubbles.

<Atmospheric pressure low-temperature plasma-containing gas>
The atmospheric pressure low-temperature plasma-containing gas in the present invention is an atmospheric pressure low-temperature plasma-containing gas having a temperature of −25 to 100° C. obtained by converting one or more raw material gases selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor into plasma under conditions of at least a pressure of 0.1 to 10 atmospheres, a raw material gas supply rate of 0.001 to 100,000 L/min, and an electric field strength of 1 to 1,000 kV/cm.

The temperature of the atmospheric pressure low-temperature plasma-containing gas is -25 to 100°C, preferably -25 to 40°C. If the gas temperature exceeds 100°C, the effect of the atmospheric pressure low-temperature plasma bubble liquid may be lost or inactivated, making it difficult to increase the plasma concentration in the plasma-containing gas. In addition, since the plasma-containing gas is at a high temperature, problems may arise in terms of safety, handling, etc. Furthermore, if the liquid medium that constitutes the liquid is water or the like with a boiling point of 100°C or less, the liquid may boil, making it difficult to include the liquid as fine bubbles.

In the present invention, the raw material gas is at least one selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor. Among these, oxygen and carbon dioxide can form a plasma-containing gas having excellent cleaning function.
The source gas is introduced into the plasma processing space to obtain atmospheric pressure low-temperature plasma-containing gas. The source gas introduced into the plasma processing space serves as both the source gas for plasma and the carrier gas.
The source of the raw gas may be a container (gas cylinder) for storing the raw gas, or, in the case where air is used as the gas, may be an outside air intake blower.

The pressure at which the plasma is generated is 0.1 to 10 atm, and preferably 0.7 to 1.5 atm. By using a mild pressure condition, there is no risk of the apparatus becoming large-scale, which is advantageous in terms of cost.
The supply rate of the raw material gas when it is introduced into the plasma treatment space is 0.001 to 100,000 L/min, preferably 0.01 to 10,000 L/min, more preferably 0.1 to 1,000 L/min, and further preferably 1 to 1,000 L/min.
If the supply rate of the raw gas is less than 0.001 L/min, the amount of plasma-containing gas generated is small, which may reduce the decomposition (cleaning) and sterilization functions of the atmospheric pressure low-temperature plasma bubble liquid. If the supply rate exceeds 100,000 L/min, the device may become large-scale, and the plasma concentration in the plasma-containing gas may decrease, which may reduce the decomposition (cleaning) and sterilization functions of the atmospheric pressure low-temperature plasma bubble liquid.

The plasma processing space into which the plasma raw material gas is introduced is provided between a pair of electrodes connected to a power source. High frequency waves, pulse waves, microwaves, etc. are applied from the power source to the pair of electrodes, and when the discharge start voltage is exceeded, an electric field is formed in the plasma processing space. At least a portion of the introduced raw material gas is converted into plasma in the plasma processing space, and then released as a plasma-containing gas. Therefore, the plasma-containing gas includes all gases obtained by converting at least a portion of the raw material gas into plasma.

The electric field strength generated in the plasma processing space is 1 to 1000 kV/cm, preferably 2 to 300 kV/cm. If the electric field strength exceeds 1000 kV/cm, the device becomes large and is disadvantageous in terms of cost, and if the electric field strength is less than 1 kV/cm, there is a risk that a sufficient amount of plasma cannot be obtained.

The electric field rise time (and fall time) is the time required for the voltage to continuously increase (or decrease) in the plasma processing space. The electric field rise time is not particularly limited and is set arbitrarily based on the gas type of the raw material gas, pressure, raw material gas supply amount, electric field strength, processing voltage, processing current, etc. For example, it is 10 μs or less, and preferably 50 ns to 5 μs. In order to make the time required for the electric field to rise 10 μs or less, it is preferable to apply a pulse wave to the electrodes.

The power in the plasma processing space is not particularly limited, and is set arbitrarily based on the type of raw material gas, pressure, raw material gas supply amount, electric field strength, processing voltage, processing current, etc. For example, it can be 100 kW/h or less, preferably 10 kW/h or less. If the power exceeds 100 kW/h, the device becomes large-scale, which may be disadvantageous in terms of cost.
The processing voltage in the plasma processing space is not particularly limited and is set arbitrarily based on the type of source gas, pressure, source gas supply amount, electric field strength, processing current, etc. For example, it can be 10 to 1000 V, preferably 20 to 600 V, and more preferably 40 to 500 V.
The treatment current in the plasma treatment space is not particularly limited and is set arbitrarily based on the type of source gas, pressure, source gas supply amount, electric field strength, treatment voltage, etc. For example, it can be 0.001 to 1000 A, preferably 0.01 to 500 A, and more preferably 0.1 to 100 A.
The frequency when applying an electric field by a pulse wave in the plasma processing space is not particularly limited, and is set arbitrarily based on the type of raw material gas, pressure, raw material gas supply amount, electric field strength, processing voltage, processing current, etc. For example, it can be 0.001 kHz or more, preferably 0.01 kHz to 300 MHz, and more preferably 0.1 kHz to 150 MHz.

The plasma used in this invention can be any scientifically defined plasma, without any particular limitations. Plasma is a high-energy gaseous state that contains charged particles produced by ionization, and it is sufficient that the number of ions and electrons is equal or nearly equal, and that the plasma is electrically neutral or nearly neutral. Plasma can be generated by various methods, such as by discharging electricity between electrodes spaced apart from each other.

Immediately after generation, the plasma in the plasma-containing gas is in a high-energy state accompanied by light emission. For this reason, it emits light in a color according to the type of plasma raw material gas, and can induce various chemical reactions. The plasma in the plasma-containing gas becomes invisible by losing part of its energy. For example, when the plasma in the plasma-containing gas is transported long distances in an air current, it gradually loses energy, becomes quenched, and finally becomes invisible. In addition, for example, the emitting plasma in the plasma-containing gas can be quenched and made invisible by an operation such as removing energy. Note that the inventor has confirmed that even when the plasma in the plasma-containing gas is quenched, the plasma contains plasma that can fully exert the function of decomposing pollutants (cleaning function) and the function of sterilization.

<Liquid>
The liquid constituting the atmospheric pressure low-temperature plasma bubble liquid of the present invention is not particularly limited as long as it is a liquid medium. For example, it may be at least one selected from the group consisting of tap water, industrial water, ultrapure water, ion-exchanged water, distilled water, and organic solvents. In the present invention, it is preferable to use water such as tap water, industrial water, ultrapure water, ion-exchanged water, and distilled water.
Also, if necessary, a mixed liquid in which various components are added to the liquid medium may be used. The various components contained in the liquid medium are not particularly limited, but may include, for example, one or more selected from the group consisting of acids, liquid bases, salts, low molecular weight organic compounds, polymeric compounds, etc. as solutes or dispersoids. By using the various components contained in these liquid media, a liquid can be made to have a desired function in addition to the function possessed by atmospheric pressure low temperature plasma. The amount of each component is not particularly limited, and may be the amount necessary to impart the desired function.

<Bubbles>
The atmospheric pressure low-temperature plasma bubble liquid of the present invention contains atmospheric pressure low-temperature plasma-containing gas obtained by plasmatizing a specific raw material gas under specific conditions as fine bubbles. The diameter of the bubbles is, for example, about 500 μm or less, preferably 200 μm or less, and more preferably 100 μm or less. In addition to such fine bubbles, bubbles with a diameter of 500 μm or more may be contained. Such fine bubbles rarely merge with each other to form larger bubbles, and are efficiently dispersed, diffused, and dissolved in the liquid due to the influence of surface tension, and can exist in the liquid for a long time. The fine bubbles are known as one or more of so-called nanobubbles, fine bubbles, and microbubbles.
The atmospheric pressure low-temperature plasma bubble liquid of the present invention is a liquid in which fine bubbles containing atmospheric pressure low-temperature plasma are dispersed, diffused, and dissolved. The fine atmospheric pressure low-temperature plasma in the liquid makes it possible to obtain an atmospheric pressure low-temperature plasma bubble liquid with high pollutant decomposition (cleaning) and sterilization functions.

[Method of producing atmospheric pressure low-temperature plasma bubble solution]
The method for producing an atmospheric pressure low-temperature plasma bubble liquid of the present invention involves converting a raw material gas, which is at least one kind selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor, into plasma under conditions of at least a pressure of 0.1 to 10 atmospheres, a raw material gas supply rate of 0.001 to 100,000 L/min, and an electric field strength of 1 to 1,000 kV/cm, and adding the atmospheric pressure low-temperature plasma-containing gas having a temperature of -25 to 100°C to the liquid in the form of fine bubbles using a bubble generator.
The atmospheric pressure low-temperature plasma-containing gas and the fine bubbles are the same as those described above in [Atmospheric pressure low-temperature plasma-containing gas].
In addition, as for the plasma-containing gas producing machine and bubble generator for producing the atmospheric pressure low-temperature plasma-containing gas, the plasma-containing gas producing machine and bubble generator constituting the atmospheric pressure low-temperature plasma bubble liquid producing apparatus described later can be used.

[Atmospheric pressure low-temperature plasma bubble liquid production equipment]
The atmospheric pressure low-temperature plasma bubble liquid producing apparatus of the present invention is equipped with at least a plasma-containing gas producing machine that produces atmospheric pressure low-temperature plasma-containing gas at a temperature of -25 to 100°C by plasmatizing a raw material gas, which is one or more kinds selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor, under conditions of at least a pressure of 0.1 to 10 atmospheres, a raw material gas supply rate of 0.001 to 100,000 L/min, and an electric field strength of 1 to 1,000 kV/cm, and a bubble generator.

<Plasma-containing gas production machine>
The plasma-containing gas production apparatus is not particularly limited as long as it can convert at least a portion of a raw material gas, which is one or more types selected from the group consisting of air, oxygen, carbon dioxide, nitrogen, and water vapor, into plasma under conditions of at least a pressure of 0.1 to 10 atmospheres, a raw material gas supply rate of 0.001 to 100,000 L/min, and an electric field strength of 1 to 1,000 kV/cm, and can produce an atmospheric pressure low-temperature plasma-containing gas at a temperature of -25 to 100°C.

The plasma-containing gas producing machine has at least a raw material gas inlet section for introducing a raw material gas, a plasma processing space for converting the raw material gas into plasma, a pair of electrodes for forming the plasma processing space by forming an electric field, a power source connected to the electrodes, and a plasma-containing gas discharge section for discharging the plasma-containing gas.
The plasma-containing gas production apparatus preferably has a housing that covers the plasma processing space in order to facilitate control of pressure and the like.

The plasma raw material gas inlet connects the plasma raw material gas source to the plasma processing space. If the plasma raw material gas is air, an air supply such as a blower can be used.

The housing covering the plasma processing space can be made of a dielectric material such as glass or ceramic. Dielectrics having a dielectric constant of 2000 or less, such as barium titanate, silicon oxide, aluminum nitride, silicon nitride, or silicon carbide, can also be used. By making at least a part of the housing out of a conductive material, the housing itself can be used as an electrode.
The shape of the housing is not particularly limited and may be any shape such as a cylinder, a sphere, a box, etc. The housing covering the plasma processing space may be in the shape of a nozzle that is processed so as to become narrower toward the plasma-containing gas emission part.

The means for forming an electric field in the plasma processing space to cause discharge is not particularly limited, and any means can be used.
For example, a pair of electrodes having different polarities are formed on the outer or inner surface of the housing, facing each other at a distance from each other, and each electrode is connected to a power source to form an electric field and discharge. The pair of electrodes can be provided facing each other inside the housing that covers the plasma processing space. At least one of the pair of electrodes can be provided with a layer of an insulator or the like formed on the surface. The interval between the discharge electrodes is not particularly limited and may be appropriately set in consideration of the voltage, etc., and may be, for example, about 0.5 to 5.0 mm. When discharging using the electrodes, the plasma concentration can be increased.

Also, for example, a coil is provided on the outer or inner circumference of a housing covering the plasma processing space, and an electrode core is provided in the plasma processing space, and the coil and the electrode core are connected to a power source to form an electric field to cause discharge. The interval between the coils, the winding length, the winding diameter, the wire diameter, the interval between the electrode core and the coil, the electrode core shape, etc. are not particularly limited, and are appropriately optimized in consideration of the voltage, etc. When the housing is an elongated cylindrical shape from the raw material gas introduction part to the plasma-containing gas discharge part, if discharge is performed using a coil provided on the outer or inner circumference of the housing and a corresponding electrode core, although the discharge density is relatively low, the discharge volume through which the plasma raw material gas passes can be increased, and therefore a large amount of plasma can be generated.
In order to obtain a stable plasma discharge, it is preferable that the pair of electrodes or the coil is configured not to come into direct contact with the plasma raw material gas. Therefore, an insulating coating made of a glassy material such as quartz or alumina, or a ceramic material may be provided on the surface of the pair of electrodes or the coil by a known means such as coating.

<Bubble generator>
The bubble generator provided in the atmospheric pressure low-temperature plasma bubble liquid manufacturing device is not particularly limited as long as it has at least a gas inlet and a gas outlet and can generate fine bubbles, and various types can be used. For example, there are those that are connected in-line to the liquid path of a flowing liquid and discharge gas into the liquid by a swirling flow method to mix and generate fine bubbles, and those that use a stirring member or the like to mix the gas and liquid when discharging gas into water to generate fine bubbles.
Also, a combined plasma-containing gas production device and bubble generator may be used in which a plasma processing space is provided in at least one of the gas inlet, interior, and gas outlet of the bubble generator.
The diameter of the fine bubbles is, for example, about 500 μm or less, preferably 200 μm or less, and more preferably 100 μm or less. In addition to such fine bubbles, bubbles with a diameter of 500 μm or more may be included, and can be set according to the application, etc.
The gas discharge amount is not particularly limited, but is, for example, an amount exceeding 0 L/min, preferably 0.1 L/min or more, more preferably 0.5 L/min or more. The upper limit of the gas discharge amount is not particularly limited, and can be set according to the production amount, etc. For example, it can be 1000 L/min or less, or for example, 100 L/min or less.

<Other equipment, etc.>
The atmospheric pressure low-temperature plasma bubble liquid producing apparatus of the present invention can be provided with a plasma-containing gas transport path between the plasma-containing gas producing device and the bubble generator, which maintains the temperature of the plasma-containing gas at −25 to 100° C., preferably −20 to 80° C., and more preferably −10 to 40° C. This makes it possible to suppress deactivation of plasma during transport of the plasma-containing gas when the plasma-containing gas producing device and the bubble generator are separated from each other.
Furthermore, the atmospheric pressure low-temperature plasma bubble liquid manufacturing apparatus of the present invention may be provided with one or more devices selected from the group consisting of a pump for moving the liquid medium, a nozzle for dispensing the product into a container or the like, a control valve for controlling flow rate and liquid pressure, various sensors for flow rate, pressure, temperature, etc., a stirring device, a plasma-containing gas treatment device, a raw material gas transport path, etc., as necessary.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Pollutant decomposition function (cleaning function)]
Example 1
Air was supplied as a raw material gas to an atmospheric pressure low-temperature plasma-containing gas production machine at 10 L/min, and plasma was generated under conditions of a pressure of 1 atmosphere, an electric field strength of 3 kV/cm, a current value of 0.32 A (measured value), a voltage of 100 V, and a power of 25 W/h to obtain a low-temperature atmospheric pressure plasma-containing gas at 40°C.
The plasma-containing gas, whose temperature was kept at 40°C, was introduced into a bubble generator (FB-S 15A: manufactured by Sakamoto Giken Co., Ltd.) with the distance (plasma-containing gas transport path length) between the plasma-containing gas outlet of the plasma-containing gas production machine and the gas inlet of the bubble generator set to 0 m (direct connection), and was added to 20 L of tap water as fine bubbles to obtain an atmospheric pressure low-temperature plasma bubble liquid.
The obtained atmospheric pressure low-temperature plasma bubble liquid was circulated at a liquid flow rate of 20 L/min, and methylene blue was added in an amount to give 1 ppm by mass.
As shown in Table 1, the circulating liquid was withdrawn immediately after the addition of methylene blue (0 min), and 10, 20, 30, 40, 50, 60, 70, and 90 min later, and the absorbance at 664 nm was measured. The results are shown in Table 1.

<Examples 2 to 5>
Except for the length of the plasma-containing gas transport path being the distance shown in Table 1, an atmospheric pressure low-temperature plasma bubble liquid was produced in the same manner as in Example 1, and the absorbance at 664 nm was measured in the same manner as in Example 1. The results are also shown in Table 1.

<Comparative Example 1>
Instead of the plasma-containing gas, air was introduced into a bubble generator (FB-S 15A: manufactured by Sakamoto Giken Co., Ltd.) and added as fine bubbles to 20 L of tap water to produce a bubble liquid, and the absorbance at 664 nm was measured in the same manner as in Example 1. The results are also shown in Table 1.

<Examples 6 to 8, Comparative Example 2>
Except for the fact that the type of raw material gas introduced into the atmospheric pressure low-temperature plasma-containing gas production apparatus was changed from air to the gas shown in Table 1, an atmospheric pressure low-temperature plasma bubble liquid was produced in the same manner as in Example 1, and the absorbance at 664 nm was measured in the same manner as in Example 1. The results are also shown in Table 1.

<Examples 9 and 10>
Except for the feed rate of the raw material gas introduced into the atmospheric pressure low-temperature plasma-containing gas production device being the feed rate shown in Table 1, an atmospheric pressure low-temperature plasma bubble liquid was produced in the same manner as in Example 1, and the absorbance at 664 nm was measured in the same manner as in Example 1. The results are also shown in Table 1.

The relationship between absorbance at 664 nm and methylene blue concentration (ppm by mass) is roughly as shown in Table 2 below.

As shown in Table 1, in the atmospheric pressure low-temperature plasma bubble solution of Example 1, which contains plasma-containing gas including atmospheric pressure low-temperature plasma in the form of fine bubbles, methylene blue was decomposed in about 60 minutes, the absorbance at 664 nm decreased, and the solution became colorless and transparent. On the other hand, in the bubble solution containing air in the form of fine bubbles (Comparative Example 1), methylene blue was not decomposed.
It was found that the methylene blue decomposition function was maintained even if the distance (plasma-containing gas transport path length) between the plasma-containing gas outlet of the plasma-containing gas production machine and the gas inlet of the bubble generator was extended to 10 m.

It can be seen that the atmospheric pressure low-temperature plasma bubble liquid (Examples 1 to 8) using air, nitrogen, oxygen, or carbon dioxide as the raw material gas for the atmospheric pressure low-temperature plasma has excellent methylene blue decomposition function, but when argon is used (Comparative Example 2), the methylene blue decomposition function is inferior.
From this, it can be seen that the atmospheric pressure low-temperature plasma bubble liquid of the present invention, which contains the atmospheric pressure low-temperature plasma-containing gas of the present invention in the form of fine bubbles, has excellent pollutant decomposition function and is a functional liquid with excellent cleaning and sterilization functions.

[Sterilization function]
Example 11
Air was supplied as a raw material gas to an atmospheric pressure low-temperature plasma-containing gas production machine at 10 L/min, and plasma was generated under the conditions of a pressure of 1 atmosphere, an electric field strength of 3 kV/cm, a current value of 0.32 A (measured value), a voltage of 100 V, and a power of 25 W/h to obtain a low-temperature atmospheric pressure plasma-containing gas at 40° C. The plasma-containing gas, whose temperature was kept at 40° C., was introduced into a bubble generator (FB-S 15A: manufactured by Sakamoto Giken Co., Ltd.) with the distance (plasma-containing gas transport path length) between the plasma-containing gas outlet of the plasma-containing gas production machine and the gas inlet of the bubble generator set to 0 m (direct connection), and the gas was added as fine bubbles to 20 L of 4-fold diluted river water (Edogawa River, Noda City, Chiba Prefecture) to obtain an atmospheric pressure low-temperature plasma bubble liquid.
The obtained atmospheric pressure low-temperature plasma bubble liquid was circulated at a liquid flow rate of 20 L/min, and one pass (circulation time 1 minute) was performed. 1 mL of the liquid 3 hours after each treatment was added to Nissui Pharmaceutical's "Compact Dry EC" and cultured at a culture temperature of 35±1°C for 24 hours, and the number of coliform bacteria was evaluated. The coliform bacteria count was evaluated by visually counting the number of colonies stained reddish purple. The results are shown in Table 3.

<Examples 12 and 13>
The coliform bacteria count was evaluated in the same manner as in Example 11, except that the treatment with the atmospheric pressure low-temperature plasma bubble liquid was changed from one pass to 10 passes (circulation time 10 minutes) or 30 passes (circulation time 30 minutes). The results are shown in Table 3.

<Comparative Example 3>
The untreated 4-fold diluted river water was used to evaluate the coliform bacteria count in the same manner as in Example 11, except that no treatment such as circulation was performed. The results are shown in Table 3.

<Comparative Examples 4 to 6>
Air was introduced into the fine bubble generator instead of the plasma-containing gas to obtain a bubble liquid. The obtained bubble liquid was subjected to the same treatments (1 pass, 10 passes, and 30 passes) as in Examples 11 to 13, and the coliform bacteria count was evaluated in the same manner as in Example 11. The results are shown in Table 3.

<Comparative Example 7>
The plasma-containing gas was not introduced into the bubble generator, and the solution was bubbled for 30 minutes to obtain an atmospheric pressure low-temperature plasma injection solution. The coliform bacteria count of the obtained atmospheric pressure low-temperature plasma injection solution was evaluated in the same manner as in Example 11. The results are shown in Table 3.

As shown in Table 3, the atmospheric pressure low-temperature plasma bubble liquids of Examples 11 to 13 have superior sterilization function compared to the air bubble liquids of Comparative Examples 4 to 6 and the atmospheric pressure low-temperature plasma injection liquid of Comparative Example 7.

Claims (3)

A raw material gas which is at least one selected from the group consisting of air, oxygen, carbon dioxide and nitrogen is at least
Pressure : 0.7 to 1.5 atmospheres
A feed gas supply rate of 0.1 to 1000 L/min and an electric field strength of 2 to 300 kV/cm;
The atmospheric pressure low-temperature plasma bubble liquid is obtained by adding atmospheric pressure low-temperature plasma-containing gas having a temperature of -25 to 40°C obtained by plasmatizing the gas under the above conditions to a liquid as fine bubbles having a diameter of 500 μm or less . A raw material gas which is at least one selected from the group consisting of air, oxygen, carbon dioxide and nitrogen is at least
Pressure : 0.7 to 1.5 atmospheres
A feed gas supply rate of 0.1 to 1000 L/min and an electric field strength of 2 to 300 kV/cm;
The atmospheric pressure low-temperature plasma-containing gas having a temperature of -25 to 40°C obtained by plasmatizing the gas under the above conditions is added to the liquid as fine bubbles having a diameter of 500 μm or less using a bubble generator. A raw material gas which is at least one selected from the group consisting of air, oxygen, carbon dioxide and nitrogen is at least
Pressure : 0.7 to 1.5 atmospheres
A raw material gas supply rate of 0.1 to 1000 L/min and an electric field strength of 2 to 300 kV/cm;
The atmospheric pressure low-temperature plasma bubble liquid producing device includes at least a plasma-containing gas producing device that produces atmospheric pressure low-temperature plasma-containing gas at a temperature of -25 to 40°C by plasmatizing the gas under the above conditions, and a bubble generator that generates fine bubbles with a diameter of 500 μm or less.