JPH11104655A - Method for generating oh radical and method for sterilization by oh radical - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a large amount of OH radicals in a short time and to minimize residual undecomposed hydrogen peroxide by generating OH radicals by the chemical reaction in which hydrogen peroxide is mixed into pure water and ultrasonic energy is given. SOLUTION: An inner container 2 made from quartz and others is arranged in an outer container 1 made from stainless steel and others, a liquid 3 having good ultrasonic wave transmission is put in the outer container 1, a solution 4 prepared by mixing hydrogen peroxide in pure water is put in the inner container 2, and ultrasonic waves of 500 K-5 MHz frequency and of 250 W-1.5 kW output are generated from an ultrasonic wave generating part 5 on the outside of the outer container 1 so that the hydrogen peroxide is reacted to produce OH radicals for sterilization or organic substance decomposition treatment in the solution 4. When the solution 4 is mixed with bacteria, mold, or organic substances in a concentration of the normal living environment, and the ultrasonic wave generating part 5 is turned on, OH radicals are generated rapidly in a solution 5 to kill the bacteria and the mold and to decompose the organic substances into carbon dioxide and water in three minutes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing OH radicals for efficiently producing OH radicals in a short time, and to a disinfection method for disinfecting with OH radicals as one of the applications of the generated OH radicals. .

[0002]

2. Description of the Related Art Japanese Patent Laid-Open Publication No.
Make 01wt% ~0.1wt% hydrogen peroxide solution H ₂ O _2, the sterilization method used for sterilization which was heated to 30-60 degrees Celsius is disclosed.

[0003] Also, JP-A-9-64146 discloses that
A cleaning method is disclosed in which a cleaning liquid comprising hydrogen fluoride HF, hydrogen peroxide H ₂ O ₂ , a surfactant and pure water is subjected to ultrasonic waves for cleaning. In this case, the concentration of hydrogen peroxide H ₂ O ₂ is 0.1 to 10% by weight.

[0004]

However, in the former sterilization method, since the concentration of hydrogen peroxide H ₂ O ₂ is high and the remaining amount of hydrogen peroxide which does not decompose into water is relatively large, cleaning after sterilization is difficult. It takes time and effort.

[0005] The latter cleaning method cannot be applied to sterilization because it contains hydrogen fluoride HF and a surfactant, and after the cleaning, a considerable amount of pure water is not used for rinsing. I have to.

A first object of the present invention is to efficiently produce a large amount of OH radicals in a short time even if the concentration of hydrogen peroxide in pure water is low, and to chemically react and decompose hydrogen peroxide in a short time. Accordingly, an object of the present invention is to provide a method for generating OH radicals, which can minimize the remaining amount of hydrogen peroxide that does not decompose into water.

The OH radical generated according to the present invention is
It can be used not only for sterilization but also for decomposing and washing organic substances, but sterilization is the most effective. Accordingly, a second object of the present invention is to provide a high sterilizing effect even when the concentration of hydrogen peroxide in pure water is low, and to reduce the residual amount of hydrogen peroxide that does not decompose into water, thereby achieving cleaning after sterilization. OH is easy to operate, and in some cases, the washing step can be omitted.
It is to provide a sterilization method using radicals.

[0008]

According to the method for producing OH radicals of the present invention, OH radicals are produced by mixing hydrogen peroxide with pure water and applying ultrasonic energy to cause a chemical reaction.

In the present invention, pure water and hydrogen peroxide are the only substances that generate OH radicals, and no other remaining chemical substances are used. Since hydrogen peroxide is stable, OH radicals cannot be generated simply by mixing it with pure water. In the present invention, both the OH radical generation reaction and decomposition of hydrogen peroxide are simultaneously promoted by ultrasonic energy, and if ultrasonic energy is applied, OH radicals are also generated from pure water itself, so that a large amount of OH radicals can be produced in a short time. OH
Radicals can be generated, and the remaining amount of hydrogen peroxide that does not decompose can be minimized.

According to the present invention, by applying ultrasonic energy, it is possible to improve the reaction rate of hydrogen peroxide, increase the generation rate of OH radicals, and reduce the remaining amount. Even if it is lowered to about 1 μM,
There is no practical problem for purposes such as sterilization.

When the concentration of hydrogen peroxide is increased, the generation amount of OH radicals naturally increases. However, when the concentration is excessively increased, post-cleaning is troublesome and the danger increases. From such a viewpoint and also from the viewpoint of economy, the upper limit of the concentration is suitably about 100 mM.

[0012] The frequency of the ultrasonic wave is 500
About KHz to 5 MHz is appropriate.

The sterilization method according to the present invention sterilizes by the OH radical generated in the above-described manner.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

As a method of sterilizing, decomposing organic substances, or performing a washing treatment with OH radicals, a batch method and a continuous treatment method are exemplified. FIG. 1 shows an example of a batch method, in which an inner container 2 made of quartz or the like is placed in an outer container 1 made of stainless steel or the like, and a liquid having a good ultrasonic wave propagation property (normal liquid) is placed in the outer container 1. 3), the inner container 2 is filled with a solution 4 in which hydrogen peroxide is mixed in pure water, and the ultrasonic generator 5 outside the outer container 1 is supplied with a solution of, for example, a frequency of 500 kHz to 5 MHz.
By generating ultrasonic waves having an output power of 250 W to 1.5 KW, a chemical reaction is caused to hydrogen peroxide to generate OH radicals, and sterilization or organic matter decomposition treatment is performed in the solution 4. The concentration of hydrogen peroxide is 1 μM to 100 mM.

In this processing apparatus, the following considerations are required to efficiently transmit ultrasonic energy. First, since the ultrasonic wave used in the present invention has a very high frequency, it has high straightness. Therefore, in order to prevent useless reflection, the bottom surfaces of the outer container 1 and the inner container 2 need to be flat, and when generating ultrasonic waves, both bottom surfaces must be arranged in parallel. The thickness d of the bottom of both containers in such an arrangement is
In order to prevent the reflection and attenuation of the ultrasonic wave, it is desirable to set the size to half the wavelength λ of the sound wave propagating in the material. That is, d = (1/2) λ.

In such an apparatus, when bacteria, fungi, or organic substances are mixed into the solution 4 at a concentration that can be found in a normal living environment and the ultrasonic generator 5 is turned on, the solution 5 OH radicals are rapidly generated, bacteria and fungi are killed in three minutes, and organic substances are decomposed and returned to carbon dioxide gas and water. The solution 4 after turning off the ultrasonic generator 5 becomes sterile water, and there is almost no remaining hydrogen peroxide. This is because, in the process of generating OH radicals, hydrogen peroxide is decomposed by ultrasonic waves.

If it is not desired to raise the temperature of the solution 4 in the inner container 2, the liquid 3 in the outer container 1 may be circulated so as to be constantly replaced by an external low-temperature liquid.

In the batch system shown in FIG. 1, the inner container 2 is not always necessary, and even if the solution containing hydrogen peroxide is directly put into the outer container 1, the same or more effect can be obtained. Also in this case, the thickness of the outer container 1 is set as described above.

FIG. 2 shows an example of a continuous processing method using nozzles. In this example, the cavity 7 of the nozzle body 6
An ultrasonic generator 5 is disposed inside the nozzle body, and while pure water is press-fitted into the cavity 7 from the pure water inlet 8 of the nozzle body 6, hydrogen peroxide is put into and mixed from the hydrogen peroxide mixing port 9, and the solution is mixed. The liquid is jetted from the injection port 10 and sprayed onto the object to be cleaned 12 as a liquid column 11.

If the liquid column 11 is not too long, it will be continuous with the solution in the cavity 7.
It is considered that an OH radical generation reaction occurs also in the above, and a sterilization / cleaning effect by the OH radical is expected on the surface of the cleaning object 12. Volume of cavity 7 and injection port 10
The size varies depending on the use conditions.

FIG. 3 shows another example of the continuous processing method. In this example, a plurality of hydrogen peroxide inlets 13 are provided at predetermined intervals in a flow path 12 such as a pipe, and an ultrasonic generator 14
, And an auxiliary ultrasonic generating unit 15 is arranged downstream of such an arrangement.

In the case of the example shown in FIG. 3, pure water is caused to flow through the flow path 12 and hydrogen peroxide is injected from the ultrasonic generator 15 at the same time as or slightly before injection of hydrogen peroxide from the hydrogen peroxide mixing port 13. Generates sound waves. The plurality of hydrogen peroxide inlets 13 and the ultrasonic generators 14 are arranged because various operation modes are assumed. For example, the hydrogen peroxide inlet 13 operates only one of the uppermost streams, Ultrasonic generator 14
If all are actuated, O
The H radical generation reaction can be sufficiently caused.
The downstream ultrasonic generator 15 is for decomposing the residual hydrogen peroxide, which also generates OH radicals by decomposing water, but here, the main purpose is to decompose hydrogen peroxide. It is desirable that the energy be lower than that of the ultrasonic generating unit 14 on the upstream side. Hydrogen peroxide mixing port 13,
The number of ultrasonic generators 14 and 15 and their relative positions can be appropriately determined according to the purpose of use.

As a modification of FIG. 3, if the flow path 12 is circulated in a loop, for example, the hydrogen peroxide concentration is made higher than that in FIG. In addition, the sterilizing / washing effect increases.

In the example shown in FIG. 2, a valve which can be opened and closed by remote automatic operation is provided in the injection port 10, and pure water and hydrogen peroxide are injected into the cavity 7 to generate ultrasonic waves. By opening the valve, it is possible to ripen the generation of OH radicals and then perform a sterilization / cleaning treatment. In this case, the valve is opened and closed intermittently.

<Experimental Examples> Next, experimental examples performed by the present inventors and the results thereof will be described.

The experimental apparatus can be represented by a schematic diagram as shown in FIG. 1, and in order to suppress the temperature rise in the inner container 2,
Tap water was constantly flowed into and out of the outer container 1. The volume of the outer container 1 was 4 liters, the volume of the inner container 2 was 1 liter, and a flat bottom flask made of quartz glass was used. The energy of the ultrasonic wave was 500 W, and the frequency was 950 KHz. 100 ml of the solution 4 of the batch was placed in the inner container 2.
The solution is prepared by preparing a hydrogen peroxide solution of a predetermined molar concentration in pure water, mixing an appropriate amount of DMPO, which is a radical trapping agent for OH radicals, and mixing well. Was a sample to which no ultrasonic wave was applied.

Thereafter, ultrasonic waves were applied to measure the time, and 1 milliliter was collected at each measurement time.
The method of measuring R was adopted.

In such an experiment, the generation efficiency of OH radical was highest when the concentration of hydrogen peroxide was about 100 μM. In terms of the amount of OH radicals generated, increasing the concentration of hydrogen peroxide to the order of mM should increase the amount, but the higher the efficiency of production in the order of μM, the higher the concentration. Is inhibited or, in fact, many occur, but due to the high concentration, the self-extinction reaction proceeds rapidly, and furthermore, DMPO-OH (5.5-dimethyl)
-1-Pyrroline-N-Oxide) itself is also decomposed in large quantities, and it is not clear whether it was not detected during ESR measurement. Here, the fact that about 100 μM was good is the result from the viewpoint of efficiency,
It is not limited to about μM. FIG. 4 shows the amount of OH radical generated when the concentration of hydrogen peroxide is 100 μM in comparison with the case where pure water alone is used.

Further, in order to try the bactericidal effect by the OH radical generated in this way, stearo thermophilus (Ba), which is a heat-resistant bacillus normally present in the air, is used.
cillus Stearothermophilus) spores were selected. The reason for choosing this is that the spores are very tough, survive in boiling water at 100 ° C, and require more than 10 minutes of heating with steam at 121 ° C or higher to completely kill them, He thought that if the spores could be killed, most of the other bacteria could be killed.

In the above OH radical measurement experiment, D
Instead of adding MPO, the diluted spore suspension was added to the batches to make up to 100 milliliters, thereby bringing each batch to 1500 cells / ml. This was irradiated with ultrasonic waves, and after 3 minutes, 1 ml was collected, divided and applied to the medium in four sterilized petri dishes, cultured at 50 ° C. for 2 weeks, and the number of generated colonies was counted. For each concentration of hydrogen peroxide, four samples were made and cultured
This is to reduce measurement unevenness. The results are shown in a line graph in FIG. In this graph, the horizontal axis represents the molar concentration of hydrogen peroxide, and the vertical axis represents the number of colonies resulting from the culture.

From this graph, it can be seen that the hydrogen peroxide concentration is 100
It is presumed that a bactericidal effect occurs from around μM / l, and that bactericidal was almost completely performed at 1 mM / l or more.

FIG. 6 is a line graph showing experimental results obtained by measuring the relationship between the generation amount of OH radicals and the ultrasonic irradiation time using the molar concentration of hydrogen peroxide as a parameter. FIG. 7 shows the results of examining the germination rate of spores by changing the hydrogen peroxide concentration stepwise from 0 to 100 mM and changing the ultrasonic irradiation time stepwise from 0 to 5 minutes for each concentration. FIG. 8 shows this as a three-dimensional bar graph. Hydrogen peroxide concentration is 0.1 mM (100 μM), 10 mM, 10 mM
In each case of 0 mM, the germination rate was 0 when the ultrasonic irradiation time was 3 minutes.

[0034]

As described above, according to the present invention, both the generation of OH radicals by hydrogen peroxide and the decomposition of hydrogen peroxide are simultaneously promoted by ultrasonic energy, and if ultrasonic energy is applied, Since OH radicals are also generated from the pure water itself, a large amount of OH radicals can be generated in a short time, and the remaining amount of undecomposed hydrogen peroxide can be minimized.

Therefore, sterilization, decomposition of organic substances, washing and the like can be efficiently performed in a short time. In addition, the remaining amount of hydrogen peroxide that does not decompose is small, and pure water and hydrogen peroxide are the only substances that generate OH radicals. Other remaining chemical substances are not used. Even if the amount of hydrogen is reduced, the effect of sterilization or the like can be obtained in a short time, which is advantageous in terms of economy, has less risk, and facilitates post-treatment.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of an apparatus for generating OH radicals in a batch mode by the method of the present invention.

FIG. 2 is a schematic view of an example of an apparatus for generating OH radicals by a continuous processing method.

FIG. 3 is a schematic view of another example of an apparatus for generating OH radicals by a continuous processing method.

FIG. 4 is a diagram showing the results of an experiment comparing the amount of OH radicals produced when the concentration of hydrogen peroxide is 100 μM with that of pure water alone.

FIG. 5 is a graph showing the results of an experiment in which a bactericidal effect was attempted on spores of Stearo thermophilus.

FIG. 6 shows the relationship between the molar concentration of hydrogen peroxide
5 is a graph showing experimental results obtained by measuring the relationship between the generation amount of H radicals and ultrasonic irradiation time.

FIG. 7 is a diagram showing the results of an experiment in which the germination rate of spores was examined by changing the concentration of hydrogen peroxide stepwise and changing the irradiation time of ultrasonic waves stepwise for each concentration.

FIG. 8 is a three-dimensional bar graph of the result of the experiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer container 2 Inner container 3 Liquid 4 Solution 5 Ultrasonic wave generator 6 Nozzle body 7 Cavity 8 Pure water inlet 9 Hydrogen peroxide mixing port 10 Injection port 11 Liquid column 12 Cleaning object 12 Flow path 13 Hydrogen peroxide mixing port 14 Ultrasonic generator 15 Ultrasonic generator

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[Procedure amendment]

[Submission date] November 25, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

The experimental apparatus can be represented by a schematic diagram as shown in FIG. 1, and in order to suppress the temperature rise in the inner container 2,
Tap water was constantly flowed into and out of the outer container 1. The volume of the outer container 1 was 4 liters, the volume of the inner container 2 was 1 liter, and a flat bottom flask made of quartz glass was used. The energy of the ultrasonic wave was 500 W, and the frequency was 950 KHz. 100 ml of the solution 4 of the batch was placed in the inner container 2.
The solution is prepared by preparing a hydrogen peroxide solution having a predetermined molar concentration in pure water, and adding DMPO (5.5-Dimethyl-1-Py) as a radical trapping agent for OH radical.
(rroline-N-Oxide) was mixed in an appropriate amount, mixed well, and then 1 ml was first collected to obtain a sample not subjected to ultrasonic waves.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

In such an experiment, the generation efficiency of OH radical was highest when the concentration of hydrogen peroxide was about 100 μM. In terms of the amount of OH radicals generated, increasing the concentration of hydrogen peroxide to the order of mM should increase the amount, but the higher the efficiency of production in the order of μM, the higher the concentration. but what has been inhibited, or, to a matter of fact are more likely to occur, the concentration self-annihilation reaction proceeds rapidly because of the high, yet will decompose even in large quantities those of DMPO-O H its, It is not clear whether it was not detected during ESR measurement. Here, the reason that about 100 μM was good is that
This is a result from the viewpoint of efficiency, and is not limited to about 100 μM. FIG. 4 shows that the hydrogen peroxide concentration is 1
The production amount of OH radical at 00 μM is shown in comparison with the case of pure water alone.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 1/50 560 C02F 1/50 560Z B01J 19/00 B01J 19/00 C 19/10 19/10 C01B 15/01 C01B 15/01 C02F 1 / 36 C02F 1/36

Claims (8)

[Claims] 1. A method for producing OH radicals, comprising mixing hydrogen peroxide into pure water and applying ultrasonic energy to cause a chemical reaction to produce OH radicals. 2. A method for producing OH radicals, comprising mixing hydrogen peroxide into pure water so as to have a concentration of 1 μM or more and applying ultrasonic energy to cause a chemical reaction to produce OH radicals. 3. A method for producing OH radicals, wherein hydrogen peroxide is mixed with pure water so as to have a concentration of 1 μM to 100 mM and subjected to a chemical reaction by applying ultrasonic energy to produce OH radicals. 4. An ultrasonic frequency of 500 KHz to 5 MHz.
The OH according to claim 1, 2 or 3,
How radicals are generated. 5. A sterilization method using OH radicals, wherein hydrogen peroxide is mixed with pure water and subjected to a chemical reaction by applying ultrasonic energy to generate OH radicals and sterilize. 6. A method according to claim 1, wherein hydrogen peroxide is mixed with pure water to a concentration of 1 μM or more, and is subjected to a chemical reaction by applying ultrasonic energy to generate OH radicals, which are sterilized. Sterilization method. 7. A sterilization method using OH radicals, wherein hydrogen peroxide is mixed with pure water so as to have a concentration of 1 μM to 100 mM, and is subjected to a chemical reaction by applying ultrasonic energy to generate OH radicals. 8. The frequency of the ultrasonic wave is set to 500 KHz to 5 MHz.
The OH according to claim 5, 6 or 7,
Sterilization method by radical.