JP2009183867A - Method and device for producing functional water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which disinfection and sterilization can be safely and securely performed utilizing plasma. <P>SOLUTION: A device for producing functional water includes: a treatment tank 1; a water feed source 2; water feed means 3, 4 feeding water W from the water feed source to the treatment tank; a plasma generating means 5 arranged above the treatment tank and emitting plasma toward the water surface of the treatment tank; a supporting means supporting the plasma generating means; a gas feeding source 11 feeding a gas to the plasma generating means; and water exhausting means 12, 13 exhausting water subjected to plasma treatment from the treatment tank. The plasma generating means emits generated plasma without causing electric current to flow inside the water in the treatment tank. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for producing functional water, particularly water having weak acidity and having an effect of suppressing the growth of bacteria without using chemicals.

  Conventionally, a method of disinfecting and sterilizing an object using atmospheric pressure low temperature plasma is known. As such a method, for example, a gas obtained by vaporizing a bactericidal liquid substance, a reactive gas, or a mixed gas thereof is introduced into a discharge region, and the generated plasma active species in the atmospheric low temperature plasma region is converted into a food product. A sterilization method (e.g., see Patent Document 1) that makes contact with a packaging material, packaging container, or medical material, or a method of sterilizing an object by directly injecting atmospheric low-temperature plasma into pathogenic microorganisms (e.g., Patent Document 2). Reference) exists.

  In addition, a rare gas or a mixed gas mainly composed of rare gases is introduced into a plasma reactor having opposed electrodes, plasma is generated by atmospheric pressure glow discharge, and packaging materials, containers, and medical devices positioned between the opposed electrodes There is a method of sterilization by irradiating a material or the like with plasma (for example, see Patent Document 3).

By the way, in general, microorganisms are active in a humid environment. Therefore, plasma radiation light and active species generated by a plasma generator in atmospheric pressure do not come into direct contact with microorganisms. This is because these microorganisms are surrounded by water.
Therefore, the conventional sterilization method using plasma as described above cannot reliably break the barrier of the water shield surrounding the microorganisms and cannot be disinfected and sterilized safely and reliably. It was not effective for disinfection or sterilization of contained objects or liquids.

JP 2001-54556 A JP 2006-102004 A JP-A-8-156920

  Accordingly, an object of the present invention is to provide a method capable of performing disinfection and sterilization safely and reliably using plasma.

  In order to solve the above problems, according to the first aspect of the present invention, there is provided a method for producing functional water by irradiating water with plasma generated so that no current flows in the water. In this specification, “plasma generated so that current does not flow in water” excludes plasma generated in a state where water forms part of the current circuit and current flows in water. That means

In the configuration of the first invention, the plasma is preferably microwave plasma, and the water is preferably irradiated to the water at atmospheric pressure or higher pressure.
The plasma is preferably generated using a rare gas, and the water includes ultrapure water, ion-exchanged water, purified water, drinking water, and treated water (sewage, after washing treatment). It is preferable to consist of any one of water, chemical-treated water, etc.) or a plurality of combinations thereof.

  In order to solve the above-mentioned problem, according to the second invention, a treatment tank, a water supply source, water supply means for supplying water from the water supply source to the treatment tank, and plasma on the water surface or water of the treatment tank A plasma generating means for irradiating; a supporting means for supporting the plasma generating means; a gas supply source for supplying gas to the plasma generating means; and a draining means for discharging plasma-treated water from the processing tank. The apparatus for producing functional water is provided, wherein the plasma generating means irradiates plasma generated without flowing current in the water of the treatment tank.

  In the configuration of the second invention, the plasma generating means preferably comprises a microwave plasma generating means, and the plasma irradiation from the plasma generating means is performed in an atmospheric pressure or higher pressure. Is preferred.

Preferably, the gas supply source supplies a rare gas, and the water is ultrapure water, ion exchange water, purified water, drinking water, and treated water (sewage, after washing treatment). Of water, chemical treated water, etc.) or a plurality of combinations thereof.
Moreover, the said apparatus may be equipped with the stirring means which stirs the water in the said processing tank, and the said apparatus may be provided with the cooling means which cools the said processing tank.

According to the present invention, by directly irradiating water with plasma generated so that no current flows in the water, the pH value of the water is reduced regardless of the method of using chemicals. The concentration of active oxygen can be increased. As a result, functional water that is weakly acidic and rich in active oxygen can be efficiently produced. This functional water can suppress the growth of bacteria and has a disinfecting and sterilizing effect.
According to the present invention, such functional water can be produced in large quantities easily and at low cost without using chemicals.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a functional water production apparatus according to one embodiment of the present invention. Referring to FIG. 1, a functional water production apparatus according to the present invention includes a treatment tank 1, a water supply source 2, a water supply pipe 3 that supplies water W from the water supply source 2 to the treatment tank 1, and a middle of the water supply pipe 3. A water supply pump 4 is provided.
The water supplied from the water supply source 2 is preferably composed of any one of ultrapure water, ion-exchanged water, purified water, and distilled water, or a combination of them, but a general water supply Water or the like may be used.

Above the processing tank 1, plasma generating means 5 for irradiating plasma toward the water surface of the processing tank 1 is disposed. Although not shown, the plasma generating means 5 is supported by a suitable supporting means. As the plasma generating means, a known appropriate one can be used. In this embodiment, the plasma generating means 5 is a microwave plasma generating means, for example, a cavity type microwave plasma torch. In this case, a microwave line plasma generator may be used instead of the cavity type microwave plasma torch.
The plasma generation means is not limited to the microwave plasma generation means, and any plasma generation means that can irradiate plasma generated without flowing current in the water of the processing tank 1 may be used. That is, in the present invention, for example, one electrode is disposed in water, the other electrode is disposed above the water surface, and a high voltage is applied between the two electrodes to generate a discharge to generate plasma. The plasma generating means having such a configuration is excluded.
The plasma generating means is preferably capable of generating and irradiating plasma at atmospheric pressure or higher pressure.

  In FIG. 1, a cavity type microwave plasma torch 5 includes a cylindrical cavity 6 with both ends opened and a discharge tube 7 extending through the cavity 6 in the central axis direction. The cavity 6 is made of a conductor such as copper, and the discharge tube 7 is made of a dielectric such as quartz.

  An antenna (not shown) is provided on the side wall of the cavity 6, and one end side of the coaxial cable 8 is connected to the antenna. The other end side of the coaxial cable 8 is connected to a microwave power source 9.

  A gas supply source 11 is connected to the upper end of the discharge tube 7 through a gas supply tube 10. The gas supply source 11 supplies a rare gas such as argon. By supplying microwaves from the microwave power source 9 into the cavity 6, rare gas plasma is irradiated from the lower end opening of the discharge tube 7.

A drainage port is formed in the lower side wall of the treatment tank 1, and a drainage pipe 12 for discharging plasma-treated water is connected to the drainage port. An opening / closing valve 13 is provided in the middle of the drain pipe 12.
Moreover, the processing tank 1 is arrange | positioned in the cooling water tank 14 provided with the well-known appropriate water cooling apparatus (not shown). In addition, the drain pipe 12 of the treatment tank 1 is disposed so as to penetrate the side wall of the cooling water tank 14 and extend to the outside.

Further, a magnetic stirrer main body 15 is disposed below the cooling water tank 14, and a magnetic stirrer stirrer 16 is disposed in the treatment tank 1, and the water W in the treatment tank 1 is It can be stirred. In this case, another known stirring means may be used instead of the magnetic stirrers 15 and 16. Stirring means is provided as necessary.
Instead of providing a stirring means, the microwave plasma torch 5 is moved to move the plasma irradiation area over the entire water surface of the processing tank 1, or the supply speed of the water W to the processing tank 1 and the processing tank 1 The effect similar to that of the agitation means can be obtained by adjusting the discharge rate of the water W after the treatment to generate a constant water flow in the treatment tank 1.

Hereinafter, operation | movement of the functional water manufacturing apparatus of this invention is demonstrated easily.
The entire functional water production apparatus of the present invention is arranged in atmospheric pressure. When the open / close valve 13 of the drain pipe 12 is closed, the water W is supplied from the water supply source 2 into the treatment tank 1 through the water supply pipe 3, and when a certain amount of water W is stored in the treatment tank 1. The supply of water W is stopped. Then, the magnetic stirrers 15 and 16 are switched on and the water W is stirred.

  A microwave having a predetermined wavelength is output from the microwave power source 9 into the cavity 6 through the coaxial cable 9. In addition, gas is introduced into the discharge tube 7 from the gas supply source 11 through the gas introduction conduit 10, whereby plasma is generated in the discharge tube 7 and directed from the lower end opening of the discharge tube 7 toward the water surface of the treatment tank 1. The water W is subjected to plasma treatment.

  When a certain period of time has elapsed and the entire water W in the treatment tank 1 has been plasma treated, the operation of the microwave plasma torch 5 and the magnetic stirrers 15 and 16 is stopped, the open / close valve 13 is opened, and the treatment is performed. Water W after the plasma treatment is taken out from the tank 1. Thereafter, the opening / closing valve 13 is closed, and new water W is supplied to the treatment tank 1, and plasma treatment of new water W is performed in the same manner as before.

  When the water W is plasma-treated, its pH value is lowered to show weak acidity, and it contains abundant active oxygen. Thus, according to the present invention, functional water that is weakly acidic and rich in active oxygen is produced. This functional water can suppress the growth of bacteria and has a disinfection and sterilization effect.

Next, an experiment was conducted to examine the characteristics of the functional water obtained by the functional water production apparatus according to the present invention.
Example 1
A glass petri dish having a diameter of 90 mm was used as the processing tank 1, the petri dish 1 was placed in the cooling water tank 14, and 20 ml of purified water W was stored in the petri dish 1. The inner diameter of the discharge tube 7 of the cavity type microwave plasma torch 5 was 10 mm, and the length of the cavity 6 was 150 mm. Then, while applying a microwave of 2.45 GHz and 400 W, argon gas (99.99%) was introduced into the discharge tube 7 at a rate of 2 liters / minute. The distance between the lower end opening of the discharge tube 7 and the water surface of the petri dish 1 was set to z = 25 mm. The temperature of the plasma gas was 827K at the position of z = 25 mm.

Then, argon gas plasma was irradiated for 10 minutes toward the water surface of the petri dish 1. During the plasma irradiation, the purified water from the petri dish was slowly stirred by the magnetic stirrers 15 and 16.
As soon as plasma irradiation was stopped after 10 minutes of plasma irradiation, the petri dish 1 was placed in a temperature-controlled water tank, and then the temperature of the purified water in the petri dish 1 was maintained at 303 K for 30 minutes. .

(Comparative Example 1)
A device similar to the above is used, and the cooling water tank 14 is covered with light so that the plasma gas is not applied to the water W of the petri dish 1, but only light (plasma radiation light) is applied to the water surface of the petri dish 1. As soon as plasma irradiation was stopped, the petri dish 1 was placed in a temperature-controlled water tank, and then the temperature of the purified water in the petri dish 1 was maintained at 303 K for 30 minutes.

(Comparative Example 2)
Untreated purified water was used as Comparative Example 2.
(Comparative Example 3)
Acidic water with pH = 4.7 was prepared by mixing 0.1N HCl in untreated purified water.

Using an illuminometer (Luminescent sensor PSN AB-2200, manufactured by AT) and a luminol solution (Bactormix AB-2960 manufactured by AT), changes in the amount of active oxygen contained in purified water according to the examples over time are integrated. It measured as luminescence intensity (ICLI). For measurement, 90 μl of purified water from Petri dish 1 and a buffer solution (0.1 M KH ₂ PO ₄ and 0.05 mM EDTA2Na, PH = 7.4) were pipetted into a test tube, and 100 μl of luminol solution was placed in the test tube. Was done by injecting.

  The measurement results are shown in the graph of FIG. Referring to the graph of FIG. 2, the amount of active oxygen in purified water before plasma irradiation was 1496 counts / 10 seconds on average. And when plasma irradiation with respect to purified water was started, the amount of active oxygen in purified water increased rapidly, and reached 30500 counts / 10 seconds at the maximum after 10 minutes passed. Even after 30 minutes have passed since the plasma irradiation was stopped after 10 minutes, about 43% of active oxygen at the peak remained in the purified water.

  Next, using the same illuminometer and luminol solution as described above, the active oxygen contained in the purified water according to the example while changing the distance z between the lower end opening of the discharge tube 7 of the microwave plasma torch 5 and the water surface of the petri dish 1. The amount was measured. The measurement results are shown in the graph of FIG. As can be seen from the graph of FIG. 6, it can be seen that the amount of active oxygen contained decreases as the distance between the lower end opening of the discharge tube 7 and the water surface of the petri dish 1 increases. This means that the closer to the lower end opening of the discharge tube 7, the higher the plasma energy, and therefore the stronger the reaction with purified water.

Further, using the same illuminometer and luminol solution as described above, Examples (purified water irradiated with plasma), Comparative Example 1 (purified water irradiated only with plasma radiation) and Comparative Example 2 (untreated purified water) The amount of each active oxygen contained was measured as integrated chemiluminescence intensity.
The measurement results are shown in the graph of FIG. As shown in the graph of FIG. 3, the amounts of active oxygen contained in purified water irradiated with plasma, purified water irradiated only with plasma radiation, and untreated purified water were 30500 counts / 10 seconds on average, respectively. Count / 10 seconds, and 1490 counts / 10 seconds. From this, it can be seen that the amount of active oxygen contained increases when the purified water is irradiated with plasma. Further, it can be seen that even if the purified water is irradiated with only the plasma radiation, the amount of active oxygen contained does not increase so much, and thus the plasma radiation hardly affects the increase in the amount of active oxygen in the purified water.

Next, the change with time of the PH value of purified water according to the example was measured. The measurement results are shown in the graph of FIG. Referring to the graph of FIG. 4, the pH value of purified water decreased from 6.49 to 4.84 by plasma irradiation. Then, after 30 minutes had elapsed, the PH value took the minimum value of 4.89, and thereafter, the PH value hardly changed over time. Thus, by irradiating the purified water with plasma, the pH value of the purified water could be changed to weak acidity without using a method using a normal chemical.
In this case, it is considered that the reason why the PH value is lowered is that nitrogen oxides generated in the downstream region of the irradiated plasma are dissolved in purified water and nitric acid is generated.

Next, it was examined whether or not the purified water according to the example has a fungus growth inhibitory effect.
Escherichia coli NBRC3301 obtained from National Institute of Technology and Evaluation, formed from agar plates (10 g / l polypeptone, 2 g / l yeast extract, 1 g / l MgSO ₄ · 7H ₂ O, 15 g / l agar powder) (PH = 7.0) and cultured at a temperature of 303 K for 16 hours. A colony of E. coli from an agar plate is cultured with 8 ml culture solution (formed from 10 g / l polypeptone, 2 g / l yeast extract, 1 g / l MgSO ₄ · 7H ₂ O, PH = 7.0) Transferred to a tube. After 8 hours of culture, 80 μl of the culture tube liquid was transferred to 8 ml of culture medium and cultured for another 8 hours. Prior to the activity test, this E. coli culture was transferred to a centrifuge tube and centrifuged three times for 15 minutes at 2046 G in physiological saline using a centrifuge. The culture solution of E. coli was diluted 10 times with physiological saline.

  4.4 ml of purified water after plasma irradiation according to the example, 4.4 ml of untreated purified water according to comparative example 2, and 4.4 ml of acidic water according to comparative example 3 were injected into three test tubes, respectively. Then, 0.1 ml of the 10-fold diluted culture solution and 0.5 ml of 45-fold concentrated physiological saline were injected into each test tube using a pipette. At 10 minutes after the injection, 0.47 ml of the liquid was collected from each test tube and cultured for 8 hours in a culture medium having the same concentration and the same components. Then, the activity test of each of the three culture solutions was measured as turbidity (600 nm).

  The measurement results are shown in the graph of FIG. As can be seen from FIG. 5, the pH value of the purified water of the example and the pH value of the acidic water of Comparative Example 3 are 4.84 and 4.7, respectively. Regardless, the purified water of the example reduces the activity of E. coli by about 57%, whereas the acidic water of Comparative Example 3 and the untreated purified water of Comparative Example 2 have a turbidity of about the same as 1.2. Therefore, the inhibitory effect of acidic water in Comparative Example 3 is almost the same as that of untreated purified water in Comparative Example 2. From this, it can be seen that the effect of suppressing the purified water after the plasma irradiation in the examples is not weakly acidic but rather is caused by the contained active oxygen.

  The configuration of the present invention is not limited to the above-described embodiment. For example, in the above-mentioned embodiment, the lower end of the discharge tube of the microwave plasma torch is arranged at a distance from the water surface of the treatment tank, and the plasma is irradiated toward the water surface. It can also be set as the structure which puts the lower end of a discharge tube in the water of a processing tank, and irradiates plasma in the water of a processing tank. In this case, it is preferable to provide at least one opening in the peripheral wall of the discharge tube and introduce air from this opening.

  In the above-described embodiment, the apparatus of the present invention is configured to perform plasma irradiation at atmospheric pressure. However, the apparatus of the present invention may be operated at a high pressure of atmospheric pressure or higher to perform plasma irradiation. Good.

  Further, the present invention is applied to a purification treatment process, and the sewage is subjected to plasma irradiation to purify the sewage, and the present invention is applied to a production process of wine, beer, etc. It is possible to improve the quality of the taste and the like. In addition, the present invention can be applied to a post-chemical treatment process, a semiconductor processing process, and the like.

It is a figure which shows schematic structure of the functional water manufacturing apparatus by this invention. It is the graph which measured the change over time of the amount of active oxygen contained in purified water irradiated with plasma according to the present invention as integrated chemiluminescence intensity (ICLI). It is the graph which measured each amount of active oxygen contained in purified water irradiated with plasma, purified water irradiated only with plasma radiation light, and untreated purified water as ICLI. It is the graph which measured the change with time progress of pH value of the purified water irradiated with plasma by the present invention. It is a graph which respectively shows the result of the activity test of colon_bacillus | E._coli in the culture solution containing the purified water irradiated with plasma, the purified water irradiated only with plasma radiation light, and untreated purified water. It is the graph which measured the change of the amount of active oxygen contained in the purified water irradiated with the plasma according to the present invention as the plasma irradiation distance changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Treatment tank 2 Water supply source 3 Water supply pipe 4 Water supply pump 5 Cavity type microwave plasma torch 6 Cavity 7 Discharge pipe 8 Coaxial cable 9 Microwave power supply 10 Gas supply pipe 11 Gas supply source 12 Drain pipe 13 Opening and closing valve 14 Cooling water tank 15 Magnetic stirrer body 16 Stirrer W Water

Claims (12)

  A method for producing functional water by irradiating water with plasma generated so that no current flows in the water.   The method of claim 1, wherein the plasma is a microwave plasma.   The method according to claim 1 or 2, wherein the water is irradiated with the plasma at a high pressure of atmospheric pressure or higher.   The method according to claim 1, wherein the plasma is generated using a rare gas.   The said water consists of any one of ultrapure water, ion-exchange water, purified water, and distilled water, or a plurality of combinations thereof. The method of crab. A treatment tank;
A water supply,
Water supply means for supplying water from the water supply source to the treatment tank;
Plasma generating means for irradiating plasma on the water surface or water of the treatment tank;
Supporting means for supporting the plasma generating means;
A gas supply source for supplying gas to the plasma generating means;
Drainage means for discharging plasma-treated water from the treatment tank,
The apparatus for producing functional water, wherein the plasma generating means irradiates plasma generated without flowing current in the water of the treatment tank.   The apparatus according to claim 6, wherein the plasma generating means is a microwave plasma generating means.   The apparatus according to claim 6 or 7, wherein the plasma irradiation from the plasma generating means is performed in an atmospheric pressure or higher pressure.   The apparatus according to claim 6, wherein the gas supply source supplies a rare gas.   The said water consists of any one of ultrapure water, ion-exchange water, purified water, and distilled water, or a plurality of combinations thereof. A device according to the above.   The apparatus according to any one of claims 6 to 10, further comprising stirring means for stirring water in the treatment tank.   The apparatus according to claim 5, further comprising a cooling unit that cools the treatment tank.

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