JP2019166408A - Decontamination method using chlorine oxide gas - Google Patents

Abstract

To provide a decontamination method capable of decontaminating a large space safely and in a short time compared with conventional methods without corroding contents in the space necessary to be decontaminated.SOLUTION: A decontamination method for removing contaminants by providing gas-phase chlorine dioxide to a closed space and reducing chemical corrosion of contents in the closed space includes a step for generating the chlorine oxide gas in the closed space under an environment of steam of 10 g/mor less and a step for introducing the chlorine oxide gas to the closed space at a chlorine oxide gas concentration of 230 ppm or less and a CT value of 50-2,000 ppm hr.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a decontamination method for a closed space by applying vapor phase of chlorine dioxide.

  The decontamination method using formalin has been utilized as a mainstream decontamination method in pharmaceutical manufacturing facilities and the like because of the excellent permeability of formaldehyde. However, due to concerns about carcinogenicity, regulations on the use of formalin have been strengthened in each country, so studies on alternatives to formalin such as hydrogen peroxide and peracetic acid in decontamination work are proceeding.

  Hydrogen peroxide is used in decontamination of aseptic rooms, where contamination of foreign substances is severely restricted, because there is a concern about the corrosion of production equipment and interior building materials due to condensation and the removal of residual gas. It can be difficult. In addition, since a peracetic acid preparation is usually used in the form of a mist, there is a problem that it is inferior in air diffusibility and is not suitable for decontamination over a wide space.

  Chlorine dioxide gas has been approved since 1988 by the United States Environmental Protection Agency (EPA) as a fumigant sterilant. A method for sterilizing biosafety cabinets that require environmental disinfection and aseptic operation with chlorine dioxide gas is standardized by the American National Standards Institute (ANSI).

  Patent Document 1 discloses a decontamination method by introducing chlorine dioxide gas having a predetermined CT value into a closed space under environmental control.

Japanese Patent No. 5823957

  The present invention is intended for facilities that require antibacterial and antifungal measures, and can decontaminate large spaces in a safer and shorter time than conventional methods without corroding the contents in the space that requires decontamination. A decontamination method is provided.

  As a result of diligent investigations for solving the above problems, the present inventors have introduced a chlorine dioxide gas into an enclosed space under an environment with a predetermined amount of water vapor or less, thereby preventing the contents in the space from corroding. As a result, the present inventors have found that decontamination can be carried out safely and in a shorter time than the above.

That is, the present invention
[1] A method of removing contaminants by applying a gaseous phase of chlorine dioxide in a closed space and reducing chemical corrosion of contents in the closed space:
In the enclosed space in an environment with a water vapor volume of 10 g / m ³ or less;
Generating chlorine dioxide gas;
A step of introducing chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 10 to 230 ppm and a CT value of 50 to 2000 ppm.

[2] A method of removing contaminants by applying a gaseous phase of chlorine dioxide in a closed space and reducing chemical corrosion of the contents in the closed space:
In the enclosed space in an environment with a water vapor volume of 10 g / m ³ or less;
Generating chlorine dioxide gas;
A step of introducing chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 20 to 230 ppm and a CT value of 60 to 2000 ppm · hour,

[3] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 10 to 100 ppm and CT value of 50 to 200 ppm · hour effective to reduce pollutants by 3 logs, [1] or [2] Described method,

[4] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 20 to 100 ppm and a CT value of 60 to 150 ppm · hour which is effective in reducing pollutants by 3 logs, [1] or [2] Described method,

[5] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 20 to 150 ppm and a CT value of 100 to 330 ppm · hour effective to reduce pollutants by 4 logs, [1] or [2] Described method,

[6] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 50 to 150 ppm and CT value of 150 to 330 ppm · hour effective to reduce pollutants by 4 logs, [1] or [2] Described method,

[7] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 40 to 200 ppm and CT value of 130 to 600 ppm, which is effective in reducing pollutants by 5 logs, [1] or [2] Described method,

[8] including a step of introducing chlorine dioxide gas into the closed space at a chlorine dioxide gas concentration of 80 to 200 ppm effective for reducing the pollutants by 5 log and a CT value of 300 to 600 ppm, [1] or [2] Described method,

[9] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 50 to 230 ppm and a CT value of 400 to 2000 ppm effective for reducing 6 logs of contaminants, [1] or [2] Described method,

[10] including a step of introducing chlorine dioxide gas into a closed space at a chlorine dioxide gas concentration of 100 to 230 ppm and a CT value of 500 to 2000 ppm effective for reducing 6 logs of contaminants, [1] or [2] Described method,

[11] The method according to any one of [1] to [10], wherein the relative humidity in the enclosed space is 60% or less,

[12] The method according to any one of [1] to [10], wherein the relative humidity in the enclosed space is 45% or less,

[13] The method according to any one of [1] to [12], wherein the contaminant is one or more selected from the group consisting of bacteria, fungi, and viruses.

[14] The method according to any one of [1] to [12], wherein the contaminant is a spore-forming bacterium.

  According to the present invention, for facilities requiring antibacterial and antifungal measures, the decontamination of a large space is safer and quicker than before without corroding the contents in the space requiring decontamination. It can be performed. Therefore, the present invention can be a very useful technique especially in decontamination in pharmaceutical factories, food factories, etc., where the contamination of foreign substances is severely restricted.

It is a schematic diagram of the decontamination system used in this embodiment. It is a schematic graph showing the time-dependent change of the chlorine dioxide gas density | concentration in a high concentration exposure test. It is a schematic graph showing the time-dependent change of the chlorine dioxide gas density | concentration in a low concentration exposure test. It is a graph which shows the time-dependent change of the chlorine dioxide gas density | concentration in closed space of Example 32. It is the water vapor amount conversion table | surface calculated | required from relative humidity and dry-bulb temperature. It is a graph which shows the relationship between the chlorine dioxide gas CT value of Examples 1-7 and the number of residual bacteria.

  Hereinafter, the configuration of the present invention will be described in detail.

<Characteristics of chlorine dioxide gas>
Chlorine dioxide gas is characterized by being easily volatilized in an open system, and can quickly increase its concentration to a concentration effective for removing contaminants. In addition, since it easily enters a narrow space, it is possible to exert a sufficient removal effect on contaminants present in the narrow space.

  Chlorine dioxide has very good sterilizing power, approximately 500,000 times that of anhydrous ethanol generally used as a disinfectant, about 100 times that of chlorhexidine gluconate, about 100 times that of benzalkonium chloride, hypochlorous acid It has about 10 times the bactericidal power of sodium acid. Chlorine dioxide does not show a decrease in sterilizing power due to an increase in pH value unlike chlorine, and its effectiveness in a wide pH range is recognized.

  Chlorine dioxide has a broad antibacterial spectrum and exhibits excellent sterilization and bactericidal effects against contaminants such as bacteria, fungi and viruses. For example, in addition to Escherichia coli, Salmonella, Legionella, Pseudomonas aeruginosa, Vibrio parahaemolyticus, Lactococcus, Lactobacillus, Bacillus cereus, Clostridium, Campylobacter, Cladosporium, Fusarium, Kumonskabi, Blue mold, Ringworm, etc. Has been confirmed. Inactivation of viruses such as influenza virus, norovirus, HIV, hepatitis B virus, rotavirus and canine parvovirus has also been confirmed.

  Chlorine dioxide is advantageous in that it is chemically structurally stable, does not produce carcinogenic substances, has low toxicity to the human body, and is highly safe.

  Chlorine dioxide gas is decomposed in a relatively short time. Therefore, the labor and labor of post-processing after decontamination processing are saved.

<Removal of pollutants>
According to the decontamination method according to the present embodiment, contaminants can be effectively removed in a short time by applying a gaseous phase of chlorine dioxide in a closed space.

  In the present embodiment, the “closed space” does not have to be a completely sealed space, but may be a space in which chlorine dioxide gas is filled in the space. With such a space, the effects of the present invention can be sufficiently obtained. The “closed space” is not particularly limited, but it is preferably implemented in production lines, work rooms, laboratories, operating rooms, etc. in facilities such as pharmaceutical factories, food factories, hospitals, laboratories, etc., where contamination by foreign substances is severely restricted. More preferably, these are sealed spaces.

  The “closed space” can include contents selected from the group consisting of metallic objects, non-metallic objects, and combinations thereof. The metallic object in the enclosed space can be formed from a metal selected from the group consisting of steel, aluminum, iron, copper, chromium, lead, and combinations thereof. The non-metallic object can be formed from a material selected from the group consisting of wood, brick, stone, cinder concrete, ceramic tile, ceiling tile, carpet, textile, and combinations thereof. Specific examples of contents include, for example, production equipment, manufacturing machines, air conditioners, dehumidifiers, measuring instruments, analytical equipment, electronic equipment (for example, telephone equipment, computers, copiers and other electronic office equipment), lighting equipment, and the like. , Acoustic equipment, internal building materials and piping, laboratory instruments, surgical tools, tools, and other equipment.

  Examples of the “contaminant” in the present embodiment include bacteria, fungi, viruses, and the like. The “pollutant removal method” in the present embodiment means a method of disinfecting, sterilizing and / or sterilizing the contaminant.

  “Bacteria” are unicellular microorganisms that are larger than viruses and have a hard cell wall. Examples of bacteria include spore-forming bacteria such as Clostridium botulinum, Clostridium perfringens, Bacillus cereus, Bacillus subtilis, Tetanus, Bacillus anthracis, Staphylococcus, Escherichia coli, Salmonella, Legionella, Pseudomonas aeruginosa, Vibrio cholerae, Mycobacterium tuberculosis, Examples include streptococci and Vibrio parahaemolyticus. In the present embodiment, a high removal effect is exerted even against the spore-forming bacteria exemplified above, which are resistant to drying, high temperature, chemicals and the like and are difficult to remove. Examples of spore-forming bacteria include the genus Bacillus and the genus Clostridium.

  “Fungus” is a general term for fungi, excluding bacteria and deformed bacteria (slime mold), and includes molds, mushrooms, yeasts and the like.

  A “virus” refers to a structure having a simple structure in which a central nucleic acid (either DNA or RNA) is wrapped in a shell called a capsid. Examples of the virus include Ebola virus, Norovirus, Rotavirus, Influenza virus, Adenovirus, Coronavirus, Measles virus, Rubella virus, Hepatitis virus, Herpes virus, HIV and the like.

In the present embodiment, 3 log reduction, 4 log reduction, 5 log reduction, and 6 log reduction are the order of the number of bacteria remaining by the sterilization operation with respect to the initial number of bacteria carried on the biological indicator (BI), respectively. It is an index showing whether it has been reduced. Specifically, for example, when the initial number of bacteria is 2.8 × 10 ⁶ cfu, 3 log reduction is 2.8 × 10 ³ cfu or less, 4 log reduction is 2.8 × 10 ² cfu or less, and 5 log reduction is the number of bacteria. Is 2.8 × 10 cfu or less, and 6 log reduction indicates that the number of bacteria is 2.8 cfu or less.

  In the present embodiment, “disinfect” refers to a process of cleaning the enclosed space and the contents of the enclosed space, and generally refers to a 3 log reduction of viable bacteria, that is, a reduction of 99.9% or more.

  In the present embodiment, “sterilize” means a process of removing or inactivating pathogens on the enclosed space and the contents of the enclosed space, for example, killing or detoxifying the pathogenic bacteria and / or bacteria. Refers to the process and generally refers to a 4 log reduction of viable bacteria, ie a reduction of 99.99% or more.

  In this embodiment, “sterilize” refers to a process that completely eliminates the viability of microorganisms, such as killing all non-pathogenic and pathogenic spores, fungi, bacteria, and viruses. Refers to a 6 log reduction of viable bacteria, ie a reduction of 99.9999% or more. This is statistically understood by those skilled in the art as destroying all the microorganisms and their spores, i.e. having zero viability.

<Setting environmental conditions>
In this embodiment, the amount of water vapor in the decontaminated closed space is adjusted to 10 g / m ³ or less. Even when the relative humidity in the enclosed space is low, when the water vapor amount is 10 g / m ³ or more, iron, aluminum, copper, etc., which are not particularly surface-treated, have a higher risk of corrosion. Conventional indoor management (for example, Patent Document 1) based on relative humidity, which has been performed at the time of decontamination, has been insufficient to prevent corrosion of contents. Moreover, there exists an advantage by which the spreading | diffusion of chlorine dioxide gas becomes more favorable by making the amount of water vapor | steam in closed space into 10 g / m < ³ > or less. If the amount of water vapor in the closed space is maintained at 10 g / m ³ or less from the time of chlorine dioxide generation to the end of decontamination, the effect of the present invention can be sufficiently obtained. Preferably at 9.5 g / m ³ or less, more preferably 9.0 g / m ³ or less, more preferably 8.5 g / m ³ or less, particularly preferably at 8.0 g / m ³ or less . The lower limit of the amount of water vapor in the enclosed space is not particularly limited, but for example, 0.1 g / m ³ or more, 0.5 g / m ³ or more, 1.0 g / m ³ or more, 2.0 g / m ³ or more, 3 .0g / m ³ or more, it may be 4.0 g / m ³ or more.

The temperature in the enclosed space (dry bulb temperature) is preferably adjusted to 31 ° C. or lower. Within this range, the amount of water vapor is always 10 g / m ³ or less when the relative humidity is 31% or less (see FIG. 5). The room temperature in the closed space is preferably 5 to 31 ° C, more preferably 16 to 30 ° C, still more preferably 18 to 28 ° C, and particularly preferably 20 to 26 ° C.

  The relative humidity in the enclosed space is preferably 60% or less, more preferably 45% or less, more preferably 37% or less, more preferably 31% or less, and further preferably 30% or less. Yes, particularly preferably 28% or less. The lower limit value of the relative humidity in the enclosed space is not particularly limited. For example, 0.1% or more, 0.5% or more, 1.0% or more, 5.0% or more, 10% or more, 15% or more, 20 % Or more.

The amount of water vapor (g / m ³ ) can be obtained by substituting the water vapor partial pressure (hPa) and the dry bulb temperature (° C.) into the gas equation of state. The water vapor partial pressure (hPa) can be determined by multiplying the saturated water vapor pressure (hPa) by the relative humidity (%). The saturated water vapor pressure (hPa) can be obtained by substituting the dry bulb temperature (° C.) into the Telens (1930) equation. FIG. 5 shows a water vapor amount conversion table obtained from relative humidity (%) and dry bulb temperature (° C.).

In the present embodiment, it is not always necessary to operate the air conditioner and / or the dehumidifier during decontamination if it is managed that the amount of water vapor in the closed space is 10 g / m ³ or less.

<Generation of chlorine dioxide>
Although it does not specifically limit as a generation source which generate | occur | produces chlorine dioxide gas, For example, the chlorine dioxide water in which chlorine dioxide was dissolved is mentioned. From such chlorine dioxide water, dissolved chlorine dioxide gas is liberated. It does not specifically limit as a density | concentration of the chlorine dioxide dissolved in chlorine dioxide water, It adjusts suitably according to the volume of the space which should be sanitized, and the target chlorine dioxide gas density | concentration. Chlorine dioxide should just be dissolved so that it may become 0.01-0.8 mass%, for example. In this embodiment, a method of sending air into the solution (aeration), a method of reducing pressure, a method of blowing air, or the like may be adopted for chlorine dioxide water to promote liberation of chlorine dioxide gas. Among these, by performing aeration on the chlorine dioxide water, liberation of the chlorine dioxide gas is easily promoted, and the chlorine dioxide gas concentration in the closed space to be decontaminated is easily increased. As a result, the time required for decontamination is likely to be shortened.

  In addition to the above, the generation source for generating chlorine dioxide gas includes, for example, a preparation in which a sodium chlorite aqueous solution and chlorine, an inorganic acid or an organic acid are formulated. Examples of the inorganic acid include hydrochloric acid and sulfuric acid. Examples of the organic acid include citric acid, lactic acid, pyruvic acid, malic acid, tartaric acid, gluconic acid, glycolic acid, fumaric acid, malonic acid, maleic acid, oxalic acid, succinic acid, acrylic acid and the like. Chlorine dioxide gas is easily produced by the reaction between the aqueous sodium chlorite solution and these chlorine, inorganic acid or organic acid. In addition, these simple reaction systems simply mix two kinds of raw materials appropriately, so that they can be easily formulated and used by users. Examples of the preparation include sprays, smokes, gels, sheets, sticks, and the like that are adjusted so that sodium chlorite can react with chlorine, inorganic acid, or organic acid as appropriate.

  The mixing ratio when the aqueous sodium chlorite solution is reacted with chlorine, an inorganic acid or an organic acid is not particularly limited, and is appropriately selected depending on the type of raw material used. For example, when a sodium chlorite aqueous solution and hydrochloric acid are selected, hydrochloric acid may be blended in an amount of 0.3 to 15% by mass with respect to 1 to 25% by mass of sodium chlorite. In this case, it is preferable to mix 1.5 to 12% by mass of hydrochloric acid with respect to 5 to 25% by mass of sodium chlorite, and 3 to 12% by mass of hydrochloric acid with respect to 10 to 25% by mass of sodium chlorite. % Is more preferable. When the blending amount of sodium chlorite is less than 1% by mass, the amount of sodium chlorite aqueous solution required increases and convenience tends to decrease. On the other hand, when the blending amount of sodium chlorite exceeds 25% by mass, it corresponds to a deleterious substance stipulated in the Poisonous and Deleterious Substances Control Law, and the handling tends to be restricted, and the formulation tends to be difficult.

<Introduction of chlorine dioxide>
The concentration of chlorine dioxide gas introduced into the closed space is preferably 10 ppm or more, more preferably 15 ppm or more, and further preferably 20 ppm or more from the viewpoint of enhancing the effect of removing contaminants. Moreover, it is preferable that it is 230 ppm or less from a viewpoint of preventing the corrosion of the content by gaseous-phase provision of chlorine dioxide.

  FIG. 2 and FIG. 3 are schematic graphs showing changes in chlorine dioxide gas concentration over time in a high concentration exposure test of 80 ppm or more and a low concentration exposure test of less than 80 ppm, respectively. The vertical axis represents chlorine dioxide gas concentration (ppm), and the horizontal axis represents time (hours). That is, for example, when released from a generation source that generates chlorine dioxide gas, the concentration in the space is gradually increased over time. Thereafter, the concentration of chlorine dioxide gas decreases after the maximum concentration is exhibited due to the decomposition amount exceeding the generation amount. In the present embodiment, the chlorine dioxide gas suitably exhibits a decontamination effect by being used so that the maximum concentration becomes a predetermined concentration (for example, 10 ppm) or more in the process of decontamination. In addition, according to this embodiment, the reaction amount of two types of reaction liquids (sodium chlorite water and hydrochloric acid) is automatically adjusted by the discharge amount of the chemical pump, and the necessary chlorine dioxide gas is supplied to the closed space, It can be automatically controlled so as to increase to a predetermined chlorine dioxide target concentration and thereafter reach a substantially constant chlorine dioxide gas concentration.

  In this embodiment, the “CT value” is an integrated value of “chlorine dioxide gas concentration (ppm)” and “time (hour)”. For example, in FIGS. 2 and 3, the CT value is expressed as the area of a region defined by the horizontal axis and the graph. Sometimes expressed as a concentration integrated value.

  In order to reduce 3 to 4 logs, a CT value of at least 50 ppm · hour is required for low concentration exposure of chlorine dioxide gas of less than 80 ppm, and at least 140 ppm · hour for high concentration exposure of 80 ppm or more. Because high concentration exposure requires more chemicals and minimizes the risk of corrosion of the contents in the enclosed space, a low concentration exposure of less than 80 ppm is preferred for 3 log to 4 log reduction. On the other hand, in order to reduce 5 to 6 logs, low concentration exposure requires a long time for decontamination and is inefficient, and high concentration exposure can reduce the number of bacteria more efficiently. In FIG. 6, the graph showing the relationship between the chlorine dioxide gas CT value of Examples 1-7 and the number of residual bacteria is shown. CT values achieving 3 log and 4 log under low exposure conditions tend to be lower than CT values achieving 3 log and 4 log under high exposure conditions, and 5 log under high exposure conditions. It can be seen that the CT values achieving 6 and 6 log tend to be lower than the CT values achieving 5 log and 6 log under the condition of low concentration exposure.

  More specifically, for 3 log reduction, the chlorine dioxide gas concentration is preferably 10 to 100 ppm; more preferably 15 to 100 ppm; more preferably 20 to 100 ppm; still more preferably 30 to 80 ppm; particularly preferably 30 to 60 ppm. preferable. The CT value is preferably 50 to 150 ppm · hour; more preferably 55 to 150 ppm · hour; more preferably 60 to 150 ppm · hour; still more preferably 90 to 120 ppm · hour; particularly preferably 100 to 110 ppm · hour.

  For reducing 4 logs, the chlorine dioxide gas concentration is preferably 20 to 150 ppm; more preferably 25 to 150 ppm; more preferably 50 to 150 ppm; still more preferably 50 to 100 ppm; and particularly preferably 50 to 80 ppm. The CT value is preferably from 100 to 330 ppm · hour; more preferably from 110 to 330 ppm · hour; more preferably from 150 to 330 ppm · hour; even more preferably from 180 to 250 ppm · hour; particularly preferably from 190 to 240 ppm · hour.

  For a 5 log reduction, the chlorine dioxide gas concentration is preferably 40 to 200 ppm; more preferably 60 to 200 ppm; more preferably 80 to 200 ppm; still more preferably 80 to 180 ppm; and particularly preferably 100 to 150 ppm. The CT value is preferably 130 to 600 ppm · hour; more preferably 200 to 600 ppm · hour; more preferably 300 to 600 ppm · hour; even more preferably 330 to 400 ppm · hour; particularly preferably 350 to 380 ppm · hour.

  For 6 log reduction, the chlorine dioxide gas concentration is preferably 50 to 230 ppm; more preferably 70 to 230 ppm; more preferably 100 to 230 ppm; still more preferably 130 to 200 ppm; particularly preferably 160 to 190 ppm. The CT value is preferably 400 to 2000 ppm · hour; more preferably 450 to 2000 ppm · hour; more preferably 500 to 2000 ppm · hour; even more preferably 550 to 1500 ppm · hour; particularly preferably 580 to 1000 ppm · hour.

  In the present embodiment, the predetermined CT value may be achieved in the time from the start of use of the chlorine dioxide gas to the decomposition of the chlorine dioxide gas. The predetermined CT value is preferably achieved within 4 hours from the start of use of chlorine dioxide gas, more preferably within 3 hours, even more preferably within 2 hours. It is particularly preferred to be achieved within 5 hours. Since a predetermined CT value is achieved in a short time, the time required for decontamination is shortened. Therefore, in various facilities (for example, pharmaceutical factories), lines that have been suspended for decontamination (for example, pharmaceuticals) Production line) can be restarted at an early stage, and the decline in operational efficiency can be suppressed.

  In the present embodiment, the maximum concentration of chlorine dioxide gas in a predetermined space is preferably achieved within 60 minutes from the start of use of chlorine dioxide gas, more preferably within 40 minutes, More preferably, it is achieved within 30 minutes. When the maximum concentration is reached in a short time, the decontamination efficiency is increased, and the loss due to the concentration reduction rate due to decomposition is reduced with respect to the concentration increase rate. Moreover, the density | concentration of the chlorine dioxide gas in space falls, after showing the maximum density | concentration (for example, refer FIG. 3). Therefore, by showing the maximum concentration at an early stage of 60 minutes, for example, the time required to reach less than 0.1 ppm, which is the concentration that humans can enter, is shortened. As a result, in various facilities (for example, pharmaceutical factories), lines that have been suspended for decontamination (for example, pharmaceutical production lines) are restarted at an early stage, and a reduction in work efficiency is suppressed.

  The present invention will be described based on examples, but the present invention is not limited to the examples.

<Sterilization test>
The decontamination effect was confirmed using the decontamination system shown in FIG. Biological indicator 7 (Mesa Labs Mesa Strip, SPORE STRIP BIOLOGICAL INDICATOR (BI), product number ACD / 6, for chlorine dioxide gas, bacterial species Bacillus atrophaeus, in a closed space 12 (sterility-compatible room: space volume about 33 m ³ )) The initial number of bacteria 2.5 to 2.8 × 10 ⁶ cfu) was suspended so that only the required number of samples could be sampled every hour. The room temperature and humidity were controlled by the dehumidifier 5, the air conditioner 13, and the temperature / humidity indicator 14 (manufactured by VAISALA), and the amount of water vapor in the space was 10 g / m ³ or less.

  In order to measure the chlorine dioxide gas concentration in the room, a Teflon (registered trademark) tube 11 (outer diameter φ6 mm × length 20 m) connected to a suction device of a chlorine dioxide gas concentration meter 3 (CDM-5 manufactured by Earth Pharmaceutical Co., Ltd.) ) Was fixed in place in the room. Chlorine dioxide gas generator 1 (CD-700 manufactured by Earth Pharmaceutical Co., Ltd.) and chlorine dioxide gas concentration measuring devices 2 and 3 are set in the machine installation room outside the space, and a predetermined amount is passed through the gas supply pipe 9 to the sterilization-compatible room. Of chlorine dioxide gas. The chlorine dioxide gas diluted in the space is a circulation type that returns the indoor air to the gas generator through the pipe 10 for reducing the indoor air.

  The amount of reaction of the two types of reaction liquids 8a and 8b (25% sodium chlorite water and 9% hydrochloric acid) is automatically adjusted by the chemical pump discharge amount for the target chlorine dioxide gas concentration, and the required chlorine dioxide gas is aseptically handled. It was supplied to the room. The indoor concentration measurement interval was once every 2 minutes. The concentration was increased to the target concentration over about 30 minutes, and thereafter it was automatically controlled so that the chlorine dioxide gas concentration was almost constant. The chlorine dioxide gas concentration was measured over time, and the CT value was calculated.

  After the exposure, the activated carbon adsorption type chlorine dioxide gas recovery machine 4 was operated in order to remove the chlorine dioxide gas in the space which became unnecessary. In order to assist gas diffusion, the circulator 6 was always operated.

  The biological indicator 7 installed in the enclosed space is sampled at every elapse of time, taken out from the wrapping paper in a clean bench using sterilized tweezers, immersed in 2 mL of physiological saline and added with 3 glass beads, BI was crushed with a vortex mixer for 20-30 minutes. The total amount of the pulverized liquid obtained was mixed in an SCDLP agar medium and cultured in an incubator at about 37 ° C. for about 2 days, and the number of colonies generated was counted.

  In addition, the chlorine dioxide gas concentration measuring device made from ATi can also be used as a standard concentration measuring device of chlorine dioxide gas. The concentration calibration method with the chlorine dioxide gas concentration measuring instrument CDM-5 manufactured by Earth Pharmaceutical Co., Ltd. is as follows.

  Using a Tedlar bag (registered trademark), chlorine dioxide gas was collected from the chlorine dioxide gas generator 1, and 10 mL of chlorine dioxide gas was collected in a syringe shielded from light with aluminum foil. The collected chlorine dioxide gas was injected with a syringe into another container containing 2 mL of 50 ppm ethylenediamine aqueous solution, and mixed with careful shaking so that the chlorine dioxide gas was dissolved in the ethylenediamine aqueous solution. Using the mixed solution as a sample solution, the reaction product of ethylenediamine and chlorine dioxide was quantitatively analyzed by ion chromatography, and the amount of reacted chlorine dioxide gas was calculated from the obtained quantitative results. A calibration curve was created from the display value of the chlorine dioxide gas concentration measuring instrument manufactured by ATi and the quantitative result of chlorine dioxide gas. A correction coefficient was input in advance into the program of the measuring instrument so that the concentration displayed on the monitor of the measuring instrument was equivalent to the true chlorine dioxide gas concentration, based on the chlorine dioxide gas concentration measuring instrument manufactured by ATi.

(High concentration exposure test)
A high concentration of chlorine dioxide gas of 80 ppm or more was exposed to the enclosed space 12. In the enclosed space, the air conditioner 13 and the dehumidifier 5 adjusted the temperature to 19 to 26 ° C., the water vapor amount to 5 to 10 g / m ³ , and the relative humidity to 25 to 42%. Five biological indicators 7 were collected every predetermined exposure time, and the number of remaining bacteria was evaluated (Table 1).

(Low concentration exposure test)
A low concentration of chlorine dioxide gas of less than 80 ppm was exposed to the enclosed space 12. In the enclosed space, the air conditioner 13 and the dehumidifier 5 adjusted the temperature to 19 to 26 ° C., the water vapor amount to 5 to 10 g / m ³ , and the relative humidity to 25 to 42%. Five biological indicators 7 were collected every predetermined exposure time, and the number of remaining bacteria was evaluated (Table 2).

(3 log reduction test)
Table 3 shows the results of Examples 8 to 13-2 that achieved 3 log reduction.

(4 log reduction test)
Table 4 shows the results of Examples 14 to 19-2 that achieved 4 log reduction.

(5 log reduction test)
The results of Examples 20-25-2 that achieved a 5 log reduction are shown in Table 5.

(6 log reduction test)
Table 6 shows the results of Examples 26 to 31-2 that achieved 6 log reduction.

<Decomposability of chlorine dioxide gas (residual)>
(Example 32)
Using the decontamination system shown in FIG. 1, the chlorine dioxide gas concentration was measured over time for 11.5 hours from the start of use of chlorine dioxide gas (0 minutes), and the decomposability (residuality) of chlorine dioxide gas. Was evaluated. Table 7 and FIG. 4 show changes with time of the chlorine dioxide gas concentration in the enclosed space.

About 170 mL of 25% sodium chlorite aqueous solution and about 170 mL of 9% hydrochloric acid were respectively discharged at a rate of 17 mL / min to the closed space 12 (sterility-compatible chamber: space volume: about 33 m ³ ). The chlorine dioxide gas concentration in the space after about 18 minutes reached 200 ppm, and the concentration was almost stable. Thereafter, the concentration was controlled while supplying and stopping a predetermined amount of the reaction solution so that the chlorine dioxide gas concentration in the space was stabilized, and the exposure was performed for about 10 hours. In the space, the air conditioner 13 and the dehumidifier 5 adjusted the temperature to 19 to 26 ° C., the water vapor amount to 5 to 10 g / m ³ , and the relative humidity to 25 to 42%. After the decontamination, the chlorine dioxide gas in the space which became unnecessary was recovered by operating the activated carbon adsorption type chlorine dioxide gas recovery machine 4. After about 43 minutes, the chlorine dioxide concentration in the enclosed space 12 became 0 ppm, and the recovery of chlorine dioxide gas was completed.

  The startup rate and diffusivity of the space supply of chlorine dioxide gas can be performed quickly unlike hydrogen peroxide, etc .; recovery of chlorine dioxide gas is different from formalin, and adsorption to the material and re-transpiration by adsorption The gas concentration in the space became 0 ppm in a short time, and it was confirmed that the worker can safely enter the closed space after decontamination.

<Corrosion test of contents>
In the decontamination system shown in FIG. 1 (decontamination target space is about 33 m ³ ), iron bearings used in pump bearings, compressor bearings, granulators, tableting machines, and filling machines were observed after decontamination.

(Example 33)
Chlorine dioxide gas was exposed twice under the following conditions. The total CT value of 2 times was 2280 ppm · hour. The average room temperature, average relative humidity, and average water vapor amount during introduction of chlorine dioxide gas are as follows.
First time Average temperature: 20 ° C., average relative humidity: 41%, average water vapor amount: 7.10 g / m ³
Second time Average temperature: 22 ° C., average relative humidity: 41%, average water vapor amount: 7.97 g / m ³
Rust was not confirmed on the iron bearing after the second exposure, and it was confirmed that the shaft rotation was not affected.

(Comparative Example 1)
Chlorine dioxide gas was exposed under conditions of an average temperature of 29 ° C. and an average relative humidity of 39.4%. From the water vapor conversion table (FIG. 5), the average water vapor is estimated to be about 11.4 g / m ³ . The CT value was 196 ppm · hour. Rust was confirmed on the iron bearing after exposure.

  According to the present invention, for facilities requiring antibacterial and antifungal measures, the decontamination of a large space can be performed safely and in a short period of time without corroding the contents in the space requiring decontamination. It can be performed. Therefore, the present invention can be a very useful technique especially in decontamination in pharmaceutical factories, food factories, etc., where the contamination of foreign substances is severely restricted.

1: Chlorine dioxide gas generator 2: Chlorine dioxide gas concentration meter (measurement unit)
3: Chlorine dioxide gas concentration meter (suction unit)
4: Chlorine dioxide gas recovery machine 5: Dehumidifier 6: Circulator 7: Biological indicator (BI)
8a, 8b: 2 types of reaction liquid (sodium chlorite water and hydrochloric acid)
9: Gas supply pipe 10: Gas suction pipe 11: Teflon (registered trademark) tube for gas suction 12: Closed space 13: Air conditioner 14: Temperature / humidity indicator

Claims (10)

A method of removing contaminants by applying a vapor phase of chlorine dioxide in a closed space and reducing chemical corrosion of the contents in the closed space:
In the enclosed space in an environment with a water vapor volume of 10 g / m ³ or less;
Generating chlorine dioxide gas;
Introducing chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 230 ppm or less and a CT value of 50 to 2000 ppm · hour. The method according to claim 1, wherein the relative humidity in the enclosed space is 31% or less. The method according to claim 1 or 2, wherein chlorine dioxide gas is introduced into the enclosed space at a chlorine dioxide gas concentration of 10 to 230 ppm, an exposure time of 6.0 hours or less, and a CT value of 50 to 1000 ppm · hour. The method according to claim 1, wherein the CT value is 50 to 953 ppm · hour. The method according to claim 1, wherein the CT value is 50 to 149 ppm · hour. A method of reducing contaminants by 3 logs by applying a vapor phase of chlorine dioxide in a closed space and reducing chemical corrosion of the contents in the closed space:
In the enclosed space where the water vapor amount is 10 g / m ³ or less and the relative humidity is 31% or less;
Generating chlorine dioxide gas;
And introducing the chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 230 ppm or less and a CT value of 50 to 2000 ppm · hour. A method of reducing contaminants by 4 logs by applying a gaseous phase of chlorine dioxide in a closed space and reducing chemical corrosion of the contents in the closed space:
In the enclosed space where the water vapor amount is 10 g / m ³ or less and the relative humidity is 31% or less;
Generating chlorine dioxide gas;
And introducing chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 230 ppm or less and a CT value of 100 to 2000 ppm · hour. A method of reducing contaminants by 5 logs by applying a gaseous phase of chlorine dioxide in a closed space and reducing chemical corrosion of the contents in the closed space:
In the enclosed space where the water vapor amount is 10 g / m ³ or less and the relative humidity is 31% or less;
Generating chlorine dioxide gas;
And introducing a chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 230 ppm or less and a CT value of 130 to 2000 ppm · hour. A method of reducing contaminants by 6 logs by applying a vapor phase of chlorine dioxide in a closed space and reducing chemical corrosion of the contents in the closed space:
In the enclosed space where the water vapor amount is 10 g / m ³ or less and the relative humidity is 31% or less;
Generating chlorine dioxide gas;
And introducing the chlorine dioxide gas into the enclosed space at a chlorine dioxide gas concentration of 230 ppm or less and a CT value of 400 to 2000 ppm · hour. The method according to any one of claims 1 to 9, wherein the contaminant is a spore-forming bacterium.