Chlorine Dioxide Generation Device and Chlorine Dioxide Generation Method

Abstract

A chlorine dioxide generation apparatus X which is so configured that, in a solvent in a vessel 1, a chlorite, an acidic substance capable of reacting with the chlorite to generate a chlorine dioxide gas, and a buffering substance that is a salt or conjugate base of the acidic substance and has a buffering effect on the acidic substance are mixed together to generate a chlorine dioxide gas.

Description

Technical Field

[0001] The present invention relates to a chlorine dioxide generator and a chlorine dioxide generation method for generating chlorine dioxide gas in a solvent in a container.

Background Art

[0002] Conventionally, instruments and devices for generating chlorine dioxide gas by reacting a chlorite solution with an acidic substance have been known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method for generating chlorine dioxide gas described in Patent Document 1, for example, a large amount of high-concentration chlorine dioxide gas is generated at the initial stage of the reaction, and low-concentration chlorine dioxide gas is generated after a lapse of a predetermined time. For example, when it is desired to disinfect a room, indoor or other similar space with chlorine dioxide gas in an environment where people are present, it is necessary to stably generate a certain degree of low-concentration chlorine dioxide gas from the initial stage of the reaction for a long period of time.

[0005] Therefore, an object of the present invention is to provide a chlorine dioxide generator and a chlorine dioxide generation method capable of stably controlling and generating chlorine dioxide gas from the initial stage of the reaction.

Means for Solving the Problems

[0006] The characteristic configuration of the chlorine dioxide generator according to the present invention for achieving the above object is that in a solvent in a container, a chlorite, an acidic substance that reacts with the chlorite to generate chlorine dioxide gas, and a buffer substance that is a salt or conjugate base thereof having a buffering action on the acidic substance are mixed to generate chlorine dioxide gas. In the chlorine dioxide generator, before mixing the chlorite and the acidic substance, the buffer substance to sub- chlorate aqueous solution is configured to be mixed with.

[0007] In the chlorine dioxide generator of the present invention, a chlorite and an acidic substance react in a solvent in a container to generate chlorine dioxide gas. At this time, since there is a buffer substance in the solvent that is a salt or conjugate base thereof having a buffering action on the acidic substance, it is possible to make it difficult (make it substantially constant) for the pH of the solvent to fluctuate when the reaction between the chlorite and the acidic substance occurs and chlorine dioxide is generated. Therefore, chlorine dioxide gas can be stably controlled and generated from the initial stage of the reaction between the chlorite and the acidic substance.

[0008] In Example 1 and the like described later, when a buffer substance is added to the reaction system of the chlorite and the acidic substance, low-concentration chlorine dioxide gas is generated in the initial stage of the reaction, and as a result, the generation amount of chlorine dioxide gas substantially maintains the low concentration in the initial stage of the reaction over a long period. On the other hand, when a buffer substance is not added to the reaction system of the chlorite and the acidic substance, high-concentration chlorine dioxide gas is generated rapidly and in large quantities in the initial stage of the reaction, and as a result, the generation amount of chlorine dioxide gas decreases rapidly thereafter.

[0009] Therefore, when a buffer substance is added to the reaction system of the chlorite and the acidic substance as in the chlorine dioxide generator of the present invention, the concentration in the initial stage of the reaction of chlorine dioxide gas can be suppressed compared to the case where no buffer substance is added. Therefore, the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas in the initial stage of the reaction. Further, in this configuration, before mixing the chlorite and the acidic substance, the buffer substance is added to the chlorite aqueous solutionconfigured to be mixed with. Buffer substance to sub- By dissolving it in an aqueous chlorate solution, the buffer substance can be made uniform in the aqueous chlorite solution. When an acidic substance is mixed in this state, the reaction between the chlorite and the acidic substance occurs to generate chlorine dioxide, and the pH fluctuation of the solvent is less likely to occur. Therefore, since the concentration at the initial stage of the reaction can be reliably suppressed, the generation period can be further extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0010] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the chlorite is sodium chlorite or potassium chlorite, and the acidic substance is any one of an inorganic acid, an organic acid, and an amphiphilic substance.

[0011] According to this configuration, sodium chlorite or potassium chlorite as the chlorite is easily available, so the present invention can be easily implemented. Further, if the acidic substance is any one of an inorganic acid, an organic acid, and an amphiphilic substance, it can react with sodium chlorite or potassium chlorite as the chlorite to generate chlorine dioxide.

[0012] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the acidic substance is a phosphoric acid compound.

[0013] According to this configuration, if the acidic substance is a phosphoric acid compound, it is easily available, so the present invention can be easily implemented.

[0014] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the acidic substance is sodium dihydrogen phosphate or potassium dihydrogen phosphate.

[0015] According to this configuration, sodium dihydrogen phosphate or potassium dihydrogen phosphate as the acidic substance has excellent storage stability, does not generate corrosive gases, and is excellent in handling, so the present invention can be easily implemented.

[0016] A further characteristic configuration of the chlorine dioxide generator according to the present invention lies in that the buffering agent is a phosphate.

[0017] According to this configuration, if the buffering agent is a phosphate, it can surely exhibit a buffering action against the phosphate compound (sodium dihydrogen phosphate or potassium dihydrogen phosphate) as an acidic substance in the solvent in the container.

[0018] A further characteristic configuration of the chlorine dioxide generator according to the present invention lies in that the buffering agent contains at least any one of tripotassium phosphate, trisodium phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate.

[0019] According to this configuration, tripotassium phosphate, trisodium phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate as the buffering agent are easily available, so the present invention can be easily implemented.

[0020] A further characteristic configuration of the chlorine dioxide generator according to the present invention lies in that the acidic substance is acetic acid.

[0021] According to this configuration, if the acidic substance is acetic acid, it is easily available, has excellent storage stability, does not generate corrosive gases, and is excellent in handling, so the present invention can be easily implemented.

[0022] A further characteristic configuration of the chlorine dioxide generator according to the present invention lies in that the buffering agent is an acetate.

[0023] According to this configuration, if the buffering agent is an acetate, it can surely exhibit a buffering action against acetic acid as an acidic substance in the solvent in the container.

[0024] A further characteristic configuration of the chlorine dioxide generator according to the present invention lies in that the buffering agent contains at least any one of potassium acetate and sodium acetate.

[0025] According to this configuration, potassium acetate and sodium acetate as buffer substances are easily available, so the present invention can be easily implemented.

[0026] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the acidic substance is citric acid.

[0027] According to this configuration, if the acidic substance is citric acid, it is easily available, has excellent storage stability, does not generate corrosive gases, and is excellent in handling, so the present invention can be easily implemented.

[0028] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the buffer substance is a citrate.

[0029] According to this configuration, if the buffer substance is a citrate, it can surely exert a buffering action on citric acid as an acidic substance in the solvent in the container.

[0030] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the buffer substance contains at least one of potassium citrate and sodium citrate.

[0031] According to this configuration, potassium citrate and sodium citrate as buffer substances are easily available, so the present invention can be easily implemented.

[0032] A further characteristic configuration of the chlorine dioxide generator according to the present invention is that the pH of the solvent is set to 5 to 7.

[0033] According to this configuration, by setting the pH of the solvent to 5 to 7, chlorine dioxide gas at a low concentration can be generated more stably controlled from the initial stage of the reaction (see Example 5 described later).

[0034] A further characteristic configuration of the chlorine dioxide generator according to the present invention is before that the concentration of the sodium chlorite is set to 3 to 25% by weight

[0035] In Example 2 described below, when the concentration of the chlorite aqueous solution was variously changed (3 to 25% by weight), the amount of chlorine dioxide gas generated was examined, and as a result, it was possible to suppress the concentration of chlorine dioxide gas at the initial stage of the reaction and to dramatically extend the generation period while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction. Therefore, in view of safety, stability, the generation efficiency of chlorine dioxide gas, etc., it is preferable that the concentration of the chlorite is 3 to 25% by weight.

[0036] A further characteristic configuration of the chlorine dioxide generator according to the present invention lies in that a gelling agent is added to the solvent in the container.

[0037] According to this configuration, by adding a gelling agent, the solvent in the container can be gelled. Therefore, even if the container is tilted, the gelled solvent is less likely to spill from the container, and the chlorine dioxide generator can be easily handled.

[0038] A characteristic configuration of the chlorine dioxide generation method according to the present invention is that in the solvent in the container, a chlorite, an acidic substance that reacts with the chlorite to generate chlorine dioxide gas, and a buffering substance that is a salt or conjugate base thereof having a buffering action with respect to the acidic substance are mixed to generate chlorine dioxide gas. In the chlorine dioxide generation method, before mixing the chlorite and the acidic substance, the buffering substance to sub- chlorate aqueous solution is configured to be mixed.

[0039] In the chlorine dioxide generation method of the present invention, a chlorite and an acidic substance react in the solvent in the container to generate chlorine dioxide gas. At this time, since a buffering substance that is a salt or conjugate base thereof having a buffering action with respect to the acidic substance is present in the solvent, it is possible to make it difficult for the pH of the solvent to fluctuate (to be substantially constant) when the reaction between the chlorite and the acidic substance occurs and chlorine dioxide is generated. Therefore, chlorine dioxide gas can be stably controlled and generated from the initial stage of the reaction between the chlorite and the acidic substance.

[0040] Therefore, when a buffering substance is added to the reaction system of chlorite and an acidic substance as in the chlorine dioxide generation method of the present invention, the concentration of chlorine dioxide gas at the initial stage of the reaction can be suppressed compared to the case where no buffering substance is added. Therefore, the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction. Further, in this configuration, before mixing the chlorite and the acidic substance, the buffering substance is mixed with the chlorite aqueous solution in such a manner. The buffering substance to sub- is dissolved in an aqueous chlorate solution so that the buffering substance can be made uniform in the aqueous chlorite solution. When the acidic substance is mixed in this state, the reaction between the chlorite and the acidic substance occurs to generate chlorine dioxide, and the pH fluctuation of the solvent is less likely to occur. Therefore, since the concentration at the initial stage of the reaction can be surely suppressed, the generation period can be further extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0043] A further characteristic configuration of the chlorine dioxide generation method according to the present invention is that the buffering substance is said dissolved in an aqueous chlorite solution, and the acidic substance and the gelling agent are mixed.

[0044] According to this configuration, by adding a gelling agent, the solvent in the container can be gelled. Therefore, even if the container is tilted, the gelled solvent is less likely to spill from the container, and the chlorine dioxide generation method can be easily performed.

Brief Description of Drawings

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Figure 1

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Figure 10

Mode for Carrying Out the Invention

[0046] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The chlorine dioxide generator of the present invention generates chlorine dioxide gas by mixing a chlorite, an acidic substance that reacts with the chlorite to generate chlorine dioxide gas, and a buffering substance that is a salt or conjugate base thereof having a buffering action on the acidic substance in a solvent in a container. Further, the chlorine dioxide generation method of the present invention generates chlorine dioxide gas by mixing a chlorite, an acidic substance that reacts with the chlorite to generate chlorine dioxide gas, and a buffering substance that is a salt or conjugate base thereof having a buffering action on the acidic substance in a solvent in a container.

[0047] The reaction between chlorite and an acidic substance is configured to be carried out in a solvent within a container. The solvent is preferably an aqueous solution. At this time, at least one of the chlorite and the acidic substance may be in an aqueous solution state, and the two may be mixed and reacted in the container. In the present embodiment, the case where the chlorite is an aqueous chlorite solution will be described. In this case, the acidic substance may be used in any of a powder form, a solid form, and a liquid form. In the present embodiment, the case where a powder-form acidic substance is used will be described.

[0048] Figure 1 shows a chlorine dioxide generator X that adds an acidic substance B to a solvent (aqueous chlorite solution A) in a container 1 having an opening at one end, mixes the two in the container 1, and reacts them to generate chlorine dioxide gas. The container 1 of the present embodiment may be a container (chlorite-containing portion 12) capable of containing the aqueous chlorite solution A. The acidic substance B may be stored in a container (acidic substance-containing portion 13) outside the container 1, and the acidic substance B may be added into the container 1 when the chlorine dioxide generator X is used. The opening of the container 1 serves as a gas discharge portion 11 capable of discharging gas.

[0049] As the buffering substance C, which is a salt or conjugate base having a buffering action on the acidic substance B, either a solid form or a liquid form may be used. The buffering substance C may be dissolved or mixed in the aqueous chlorite solution A or the acidic substance B (powder form, solid form, and liquid form) before mixing the aqueous chlorite solution A and the acidic substance B. In the present embodiment, the case where the buffering substance C is dissolved in the aqueous chlorite solution A and then mixed with the acidic substance B will be described.

[0050] Examples of the shape of the container 1 include, but are not limited to, a bottle shape, a tubular shape (test tube shape), a stick shape, a bag shape (pouch shape), a box shape, etc. In the present embodiment, the case where the container 1 is in a bottle shape will be described. Also, the material of the container 1 is not particularly limited as long as it has heat resistance and chemical resistance. Glasses, metals such as stainless steel, and resins such as polypropylene, polyethylene, Tritan (registered trademark, manufactured by Eastman) having excellent heat resistance and chemical resistance are particularly preferred.

[0051] The gas release part 11 may be an open system, but a lid having a breathable structure or a non-permeable member having breathability can be provided. These members may be attached to the opening of the container 1 after adding the acidic substance B into the container 1. As the non-permeable member, for example, a moisture-permeable waterproof sheet (or breathable waterproof sheet) that allows gas, air, and moisture to pass through but does not allow liquid to pass through can be used. The moisture-permeable waterproof sheet may use a microporous film (a film made of a material having a large number of very small holes) alone, or a material obtained by laminating and bonding multiple sheets, a material that allows the movement of gas, air, and moisture (water vapor) even if it is non-porous, a coating-type material obtained by subjecting a high-density fabric to a strong water-repellent treatment, etc. may be used. Examples of commercially available products include Gore-Tex (registered trademark), Expor (registered trademark, manufactured by Mitsubishi Chemical Corporation), Poramu (registered trademark, manufactured by Tokuyama Corporation), Entrant E (registered trademark, manufactured by Toray Industries, Inc.), Tyvek (registered trademark, manufactured by DuPont), Melfit (registered trademark, manufactured by Unicel), etc. In addition, it is desirable that the non-permeable member has heat sealability (heat weldability) in order to facilitate attachment to the container 1.

[0052] (Chlorite) Examples of the chlorite used in the present invention include alkali metal chlorites and alkaline earth metal chlorites. Examples of the alkali metal chlorite include sodium chlorite, potassium chlorite, and lithium chlorite. Examples of the alkaline earth metal chlorite include calcium chlorite, magnesium chlorite, and barium chlorite. Among them, sodium chlorite and potassium chlorite are preferable from the viewpoint of easy availability, and sodium chlorite is most preferable. These chlorites may be used alone or in combination of two or more.

[0053] The proportion of chlorite in the aqueous chlorite solution is preferably 0.1 to 30% by weight. When it is less than 0.1% by weight, there may be a problem that chlorite is insufficient in the generation of chlorine dioxide gas. When it exceeds 30% by weight, there may be a problem that chlorite is saturated and crystals are likely to precipitate. In view of safety, stability, generation efficiency of chlorine dioxide gas, etc., 3 to 25% by weight is preferable, and a more preferable range is 3% by weight to 15% by weight.

[0054] (Acidic substance) The acidic substance that can be used in the present invention is an acid that reacts with chlorite, and is not particularly limited as long as it is preferably any of inorganic acids, organic acids, and amphiphilic substances. For example, in the case of an inorganic acid, the acidic substance may be a phosphate compound (sodium dihydrogen phosphate or potassium dihydrogen phosphate), acetic acid, sulfuric acid, etc. In the case of an organic acid, it may be citric acid, malic acid, lactic acid, etc. In the case of an amphiphilic substance, it may be 3-morpholinopropanesulfonic acid, 2-morpholinoethanesulfonic acid, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, etc. Among them, it is preferable to use a phosphate compound (sodium dihydrogen phosphate or potassium dihydrogen phosphate), acetic acid, and citric acid because of their excellent storage stability, no generation of corrosive gas, and no change in concentration during storage. The acidic substance may be used alone or in combination of two or more. Also, the acidic substance may be in any form of anhydride and hydrate.

[0055] The acidic substance may also be contained in a porous substance. As the porous substance, for example, a porous material or a fired aggregate can be used, but it is not limited thereto. Examples of the porous material include porous silica, sepiolite, montmorillonite, diatomaceous earth, talc, zeolite, activated clay, molecular sieve, activated alumina, etc. Among them, it is preferable to use porous silica in terms of easy availability, excellent porosity (wide porous space), and easy inclusion of acidic substances or chlorites. There is no particular limitation on the specific surface area of these porous silicas, etc. As the fired aggregate, for example, those obtained by firing bones of animals (including mammals, fish, and birds), shells, and corals and crushing them into flakes, particles, or powder can be used.

[0056] In the state of being contained in such a porous substance, the concentration of the acidic substance is preferably set such that the final concentration is 30% by weight or less.

[0057] (Buffer substance) The buffer substance that can be used in the present invention is not particularly limited as long as it is a salt or conjugate base having a buffering action against the acidic substance. Substances corresponding to "a salt or conjugate base having a buffering action against the acidic substance" become "a salt of the acidic substance" or "a conjugate base of the acidic substance". The buffer substance may be used alone or in combination of two or more.

[0058] When using a phosphate compound (sodium dihydrogen phosphate or potassium dihydrogen phosphate), which is an inorganic acid, as the acidic substance, the buffer substance may contain at least one phosphate of potassium phosphate, sodium phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate. When using acetic acid, which is an inorganic acid, as the acidic substance, the buffer substance may contain at least one acetate of potassium acetate and sodium acetate. When using citric acid, which is an organic acid, as the acidic substance, the buffer substance may contain at least one citrate of potassium citrate and sodium citrate. Also, the buffer substance may be in any form of anhydride and hydrate.

[0059] By dissolving the buffering substance C in the chlorite aqueous solution A, the buffering substance C can be made into a uniform state in the chlorite aqueous solution A. When the acidic substance B is mixed in this state, the fluctuation of the pH of the solvent when the reaction between the chlorite and the acidic substance occurs and chlorine dioxide is generated is less likely to occur.

[0060] In this embodiment, the acidic substance B is mixed in a state where the buffering substance C is dissolved in the chlorite aqueous solution A. However, a gelling agent may be added and mixed together with the acidic substance B.

[0061] As the gelling agent, a water-absorbing gelling agent, for example, a water-absorbing resin may be used, but it is not limited to such an embodiment. Examples of the water-absorbing resin include Aqualic (registered trademark, manufactured by Nippon Shokubai Co., Ltd.), Sunfresh (registered trademark, manufactured by Sanyo Chemical Industries, Ltd.), Aquakeep (registered trademark, manufactured by Sumitomo Seika Chemicals Co., Ltd.), KI Gel (registered trademark, manufactured by Kuraray Co., Ltd.), etc., but are not limited thereto.

[0062] The timing of adding the gelling agent to the container 1 is not limited to the above embodiment, and the gelling agent may be added after mixing the acidic substance B in a state where the buffering substance C is dissolved in the chlorite aqueous solution A.

[0063] By adding the gelling agent, the solvent in the container 1 can be gelled. Therefore, even if the container 1 is tilted, the gelled solvent is less likely to spill from the container 1, and the chlorine dioxide generator X can be easily handled.

[0064] In the chlorine dioxide generator X of the present invention, chlorine dioxide gas is generated by the reaction between the chlorite and the acidic substance in the solvent in the container. At this time, since there is a buffering substance in the solvent that is a salt or conjugate base having a buffering action with respect to the acidic substance, the fluctuation of the pH of the solvent when the reaction between the chlorite and the acidic substance occurs and chlorine dioxide is generated can be reduced (made substantially constant). Therefore, chlorine dioxide gas can be stably controlled and generated from the initial stage of the reaction between the chlorite and the acidic substance.

[0065] Therefore, when a buffering substance is added to the reaction system of chlorite and an acidic substance as in the chlorine dioxide generator X of the present invention, the concentration of chlorine dioxide gas at the initial stage of the reaction can be suppressed as compared with the case where no buffering substance is added. Thus, the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0066] The pH of the solvent is preferably 5 to 7. The pH of the solvent in this case is the pH value in the state where the aqueous sodium chlorite solution A, the acidic substance B, and the buffering substance C are mixed, and can be adjusted by the addition amount of the buffering substance C. If the pH is within this range, chlorine dioxide gas at a low concentration can be stably controlled and generated from the initial stage of the reaction. Preferably, if the pH of the solvent is adjusted to 5.5 to 7, the initial generation amount of chlorine dioxide gas can be further suppressed. More preferably, if the pH of the solvent is adjusted to 6 to 7, the initial generation amount of chlorine dioxide gas can be further suppressed.

[0067] The place where the chlorine dioxide generator X of the present invention is used is not particularly limited. For example, it can be used in general households (living rooms, entrances, toilets, kitchens, etc.), for industrial use (factory use), at medical sites such as hospitals, clinics, and nursing facilities, and at public facilities such as schools, train stations, and public toilets, and can be used in all scenarios. In addition, it can be used not only in relatively large spaces such as indoor spaces where people can live, but also in narrow spaces such as refrigerators, shoe boxes, and inside vehicles (cars, buses, trains). Thus, the size of the applicable space of the generator of the present invention is not particularly limited.

[0068] 〔Alternative Embodiment 1〕 Not limited to the above-described embodiment, a solid (powder) chlorite may be used and the acidic substance may be in a liquid state. In this case, in the container 1, it is preferable to mix with the chlorite in a state where the buffering substance C is dissolved in an aqueous solution of the acidic substance B.

[0069] The acidic substance that can be used in this form can be the above-described acidic substance. The concentration of the aqueous solution of the acidic substance is preferably 30% by weight or less.

Example

[0070] [Example 1] As the chlorine dioxide generator X of the present invention, an aqueous solution A of sodium chlorite (43 mL) with a concentration of 23.5% by weight was placed in a container 1 (bottle-shaped, volume 100 mL), 7.7 g of tripotassium phosphate (buffer substance C) was dissolved, and the acidic substance B was placed in an external container (acidic substance storage part 13) of the container 1. The acidic substance B was 8.5 g of sodium dihydrogen phosphate (powder).

[0071] Sodium dihydrogen phosphate was added into the container 1 to bring the sodium chlorite aqueous solution A into contact with sodium dihydrogen phosphate. The chlorine dioxide gas generated immediately after mixing the sodium chlorite aqueous solution A and sodium dihydrogen phosphate was discharged to the outside of the container 1 through the gas discharge part 11, and the chlorine dioxide treatment of the object to be treated was carried out in the fumigation chamber for a predetermined time. FIG. 2 is a graph showing the relationship between the amount of generated chlorine dioxide gas and time. As Comparative Example 1, the amount of generated chlorine dioxide gas when the buffer substance C was not added was shown.

[0072] As a result, in Comparative Example 1, a high-concentration chlorine dioxide gas was generated rapidly and in large quantities (up to about 3.5 mg per hour) in the initial stage of the reaction (up to about 100 hours), and a low-concentration chlorine dioxide gas was generated (0.5 mg or less per hour) when about 720 hours (about 1 month) had passed. After that, the amount of generated chlorine dioxide gas per hour gradually decreased until about 6 months had passed.

[0073] On the one hand, in Example 1 of the present invention, chlorine dioxide gas at a low concentration (0.3 mg or less per hour) was generated at the initial stage of the reaction, and thereafter, the generation amount of chlorine dioxide gas maintained the low concentration at the initial stage of the reaction over a long period (7200 hours, about 10 months). Also, when about 2500 hours (about 3.5 months) had elapsed since the start of the reaction, the generation amount of chlorine dioxide gas per hour exceeded the generation amount per hour in Comparative Example 1. Therefore, it was recognized that in Example 1 of the present invention, chlorine dioxide gas at a low concentration can be stably controlled and generated from the initial stage of the reaction. Further, in Example 1 of the present invention, since the concentration of chlorine dioxide gas at the initial stage of the reaction can be suppressed, the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction, and it was recognized that the chlorine dioxide generator X can be made to have a longer life.

[0074] 〔Example 2〕 In the chlorine dioxide generator X used in Example 1, it was investigated how chlorine dioxide gas is generated when the concentration of the chlorite aqueous solution A is variously changed (3 to 25% by weight) (Examples 2-1 to 2-4 of the present invention). The results are shown in FIG. 3. As Comparative Examples 2-1 to 2-4, the generation amounts of chlorine dioxide gas when the buffering substance C was not added were shown.

[0075] As a result, in any of Examples 2-1 to 2-4 of the present invention, it was recognized that chlorine dioxide gas at a low concentration can be stably controlled and generated from the initial stage of the reaction as compared with each of Comparative Examples 2-1 to 2-4. Therefore, if the concentration of the chlorite aqueous solution A is 3 to 25% by weight, it was recognized that the concentration of chlorine dioxide gas at the initial stage of the reaction can be suppressed, and the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0076] 〔Example 3〕 In the chlorine dioxide generator X used in Example 1, for the embodiment in which the acidic substance B is potassium dihydrogen phosphate (9.6 g) and the buffering substance C is tripotassium phosphate (7.7 g) (Example 3-1 of the present invention), and for the embodiment in which the acidic substance B is sodium dihydrogen phosphate (16.5 g) and the buffering substance C is disodium hydrogen phosphate (8.4 g) (Example 3-2 of the present invention), it was investigated how chlorine dioxide gas is generated. The results are shown in Fig. 4. As Comparative Examples 3-1 to 3-2, the generation amounts of chlorine dioxide gas when the buffering substance C was not added were shown.

[0077] As a result, in any of Examples 3-1 to 3-2 of the present invention, it was recognized that chlorine dioxide gas at a low concentration can be stably controlled and generated from the initial stage of the reaction as compared with Comparative Examples 3-1 to 3-2, respectively. Therefore, if the acidic substance B and the buffering substance C are used in combination at least as in this Example, the concentration of chlorine dioxide gas at the initial stage of the reaction can be suppressed, and it was recognized that the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0078] 〔Example 4〕 In the chlorine dioxide generator X used in Example 1, for the embodiment in which the acidic substance B is acetic acid (2.0 mL) and the buffering substance C is sodium acetate (25.4 g) (Example 4-1 of the present invention), and for the embodiment in which the acidic substance B is citric acid (6.8 g) and the buffering substance C is trisodium citrate dihydrate (41.6 g) (Example 4-2 of the present invention), it was investigated how chlorine dioxide gas is generated. The results are shown in Fig. 5. As Comparative Examples 4-1 to 4-2, the generation amounts of chlorine dioxide gas when the buffering substance C was not added were shown.

[0079] As a result, in any of Examples 4-1 to 4-2 of the present invention, it was confirmed that chlorine dioxide gas at a low concentration could be stably controlled and generated from the initial stage of the reaction as compared with Comparative Examples 4-1 to 4-2, respectively. Therefore, it was confirmed that if the acidic substance B and the buffering substance C are used in combination at least as in this Example, the concentration of chlorine dioxide gas at the initial stage of the reaction can be suppressed, and the generation period can be dramatically extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0080] 〔Example 5〕 In the embodiment of the chlorine dioxide generator X in which the acidic substance B is potassium dihydrogen phosphate and the buffering substance C is tripotassium phosphate (Example 3-1 of the present invention), when the addition amount of tripotassium phosphate as the buffering substance C was variously changed to change the pH of the reaction system, how the generation amount of chlorine dioxide gas changed was examined. The results are shown in Fig. 6. As Comparative Example 5, the generation amount of chlorine dioxide gas when the buffering substance C was not added was shown.

[0081] The pH of the reaction system of Comparative Example 5 was 4.5. Also, the pH of the reaction system when the addition amount of tripotassium phosphate as the buffering substance C was 0.5 g was 5.0 (Example 5-1 of the present invention), the pH of the reaction system when the addition amount of tripotassium phosphate was 1.7 g was 5.5 (Example 5-2 of the present invention), the pH of the reaction system when the addition amount of tripotassium phosphate was 3.5 g was 6.0 (Example 5-3 of the present invention), and the pH of the reaction system when the addition amount of tripotassium phosphate was 7.9 g was 6.7 to 7.0 (Example 5-4 of the present invention).

[0082] As a result, when tripotassium phosphate, which is the buffering substance C, is added, the amount of chlorine dioxide gas generated is 3 mg or less per hour. In any of Examples 5-1 to 5-4 of the present invention, it was confirmed that chlorine dioxide gas at a low concentration can be stably controlled and generated from the initial stage of the reaction as compared with Comparative Example 5. Further, it was found that the amount of chlorine dioxide gas generated is suppressed as the pH of the reaction system rises from 5.0 to 6.7 (about 7.0). Therefore, it was confirmed that the amount of chlorine dioxide gas generated can be controlled by adjusting the addition amount of the buffering substance C to adjust the pH of the reaction system. In particular, when the pH of the reaction system is adjusted to 5.5 to 7.0, the amount of chlorine dioxide gas generated is 2 mg or less per hour. When the pH of the reaction system is adjusted to 6.0 to 7.0, the amount of chlorine dioxide gas generated is 1 mg or less per hour. It was confirmed that chlorine dioxide gas at a low concentration can be more stably controlled and generated from the initial stage of the reaction.

[0083] In addition, in this example, although the results were shown when the acidic substance was a phosphate compound and the buffering substance was a phosphate, the same results were obtained even when the acidic substance was acetic acid and the buffering substance was acetate, and when the acidic substance was citric acid and the buffering substance was citrate (the results are not shown).

[0084] 〔Example 6〕 In the chlorine dioxide generator X used in Example 1, tripotassium phosphate, which is the buffering substance C, was dissolved in the aqueous sodium chlorite solution A and then the acidic substance B was added. On the other hand, when the buffering substance C was dissolved in the aqueous solution of the acidic substance B and then mixed with the aqueous sodium chlorite solution A (Inventive Example 6-1), and when it was mixed with the solid acidic substance B and then mixed with the aqueous sodium chlorite solution A (Inventive Example 6-2), how chlorine dioxide gas is generated was investigated. The results are shown in FIG. 7.

[0085] As a result, in any of Inventive Examples 6-1 to 6-2, the behavior of chlorine dioxide gas generation was the same as that in Inventive Example 1, and it was confirmed that chlorine dioxide gas at a low concentration can be stably controlled and generated from the initial stage of the reaction.

[0086] 〔Example 7〕 In the chlorine dioxide generator X of Example 1, the bottle-shaped container 1 was used. However, when the container 1 was made into a pouch shape (bag shape) (Example 7 of the present invention), it was examined how chlorine dioxide gas was generated.

[0087] The pouch-shaped container 1 used was a bag processed into a rectangular shape (120 mm × 200 mm) in top view (Fig. 8). The pouch-shaped container 1 contained a first storage container 10 (100 mm × 150 mm) composed of a fragile delamination-type film 10A containing an aqueous sodium chlorite solution A and a buffering substance C (tripotassium phosphate), and a second storage container 20 (80 mm × 100 mm) composed of a water-soluble PVA film containing an acidic substance B (sodium dihydrogen phosphate, powder) were stored in a stacked state. The container 1 had a gas release part 11 with at least one of the front and back surfaces being gas-permeable and liquid-impermeable.

[0088] An external force was applied by pressing with a finger from the outside of this container 1 to deform it. At this time, the external force applied to the container 1 was transmitted to the fragile first storage container 10 to deform the first storage container 10, and the internal pressure thereof increased, so that a desired layer in the delamination-type film 10A was peeled off, and the first storage container 10 could be easily broken. By breaking the first storage container 10, the aqueous sodium chlorite solution A released inside the container 1 immediately contacted the second storage container 20, and a part of the water-soluble second storage container 20 dissolved. Further, by shaking the container 1 several times to the left and right, most of the water-soluble second storage container 20 dissolved. As a result, the aqueous sodium chlorite solution, tripotassium phosphate, and sodium dihydrogen phosphate were mixed, and chlorine dioxide gas was generated.

[0089] The results are shown in Fig. 9. As Comparative Example 7, the generation amount of chlorine dioxide gas when the buffering substance C was not added was shown.

[0090] As a result, similar to the case of the chlorine dioxide generator X of Example 1, also in Invention Example 7, compared with Comparative Example 7, it was found that chlorine dioxide gas at a low concentration can be stably controlled and generated (3 mg or less per hour) from the initial stage of the reaction, and the generation period can be significantly extended while maintaining the generation concentration of chlorine dioxide gas at the initial stage of the reaction.

[0091] In addition, in this Example, the results were shown when the acidic substance was a phosphoric acid compound and the buffering substance was a phosphate, but even when the acidic substance was citric acid and the buffering substance was citrate, the same results were obtained (the results are not shown).

[0092] 〔Example 8〕 In the chlorine dioxide generator X of Example 1, when a gelling agent (water-absorbing resin: Aqualic (manufactured by Nippon Shokubai Co., Ltd.)) was added together with acidic substance B, how chlorine dioxide gas was generated was investigated (Invention Example 8). The results are shown in FIG. 10. As Comparative Example 8, the generation amount of chlorine dioxide gas when buffering substance C was not added was shown.

[0093] As a result, similar to the case of the chlorine dioxide generator X of Invention Example 1, also in Invention Example 8, it was found that chlorine dioxide gas at a low concentration can be stably controlled and generated (0.5 mg or less per hour) from the initial stage of the reaction compared with Comparative Example 8.

Industrial Applicability

[0094] The present invention can be used for a chlorine dioxide generator and a chlorine dioxide generation method for generating chlorine dioxide gas in a solvent in a container.

Explanation of Reference Numerals

[0095] X Chlorine dioxide generator A Aqueous chlorite solution B Acidic substance C Buffering substance 1 Container

Claims

1. In a chlorine dioxide generator that generates chlorine dioxide gas by mixing a chlorite, an acidic substance that reacts with the chlorite to generate chlorine dioxide gas, and a buffering substance that is a salt or conjugate base thereof having a buffering action on the acidic substance in a solvent in a container, A chlorine dioxide generator configured to mix the buffering substance with an aqueous chlorite solution before mixing the chlorite and the acidic substance.

2. The chlorine dioxide generator according to claim 1, wherein the chlorite is sodium chlorite or potassium chlorite, and the acidic substance is any one of an inorganic acid, an organic acid, and an amphiphilic substance.

3. The chlorine dioxide generator according to claim 1 or 2, wherein the acidic substance is a phosphoric acid compound.

4. The chlorine dioxide generator according to any one of claims 1 to 3, wherein the acidic substance is sodium dihydrogen phosphate or potassium dihydrogen phosphate.

5. The chlorine dioxide generator according to claim 3 or 4, wherein the buffering substance is a phosphate.

6. The chlorine dioxide generator according to claim 5, wherein the buffering substance contains at least any one of tripotassium phosphate, trisodium phosphate, dipotassium hydrogen phosphate, and disodium hydrogen phosphate.

7. The chlorine dioxide generator according to claim 1 or 2, wherein the acidic substance is acetic acid.

8. The chlorine dioxide generator according to claim 7, wherein the buffering substance is an acetate.

9. The chlorine dioxide generator according to claim 7 or 8, wherein the buffering substance contains at least any one of potassium acetate and sodium acetate.

10. The chlorine dioxide generator according to claim 1 or 2, wherein the acidic substance is citric acid.

11. The chlorine dioxide generator according to claim 10, wherein the buffering substance is a citrate.

12. The chlorine dioxide generator according to claim 10 or 11, wherein the buffering substance contains at least one of potassium citrate and sodium citrate.

13. The chlorine dioxide generator according to any one of claims 1 to 12, wherein the pH of the solvent is 5 to 7.

14. The chlorine dioxide generator according to any one of claims 1 to 13, wherein the concentration of the chlorite is 3 to 25% by weight.

15. The chlorine dioxide generator according to any one of claims 1 to 14, wherein a gelling agent is added to the solvent in the container.

16. In a method for generating chlorine dioxide gas by mixing a chlorite, an acidic substance that reacts with the chlorite to generate chlorine dioxide gas, and a buffering substance that is a salt or conjugate base having a buffering action on the acidic substance in a solvent in a container, A method for generating chlorine dioxide, wherein the buffering substance is mixed with an aqueous solution of chlorite before the chlorite and the acidic substance are mixed.

17. The method for generating chlorine dioxide according to claim 16, wherein the acidic substance and the gelling agent are mixed in a state where the buffering substance is dissolved in the aqueous solution of chlorite.

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