WO2022269749A1

WO2022269749A1 - Method and device for decomposing gaseous substance and particulate substance in gas phase

Info

Publication number: WO2022269749A1
Application number: PCT/JP2021/023571
Authority: WO
Inventors: 信幸石川; 康介太田; 広樹滝口
Original assignee: 日本たばこ産業株式会社
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-12-29

Abstract

Provided is a method with which a gaseous substance and a particulate substance in a gas phase can be efficiently decomposed. A method for decomposing a gaseous substance and a particulate substance in a gas phase, the method including a step for producing an aerosol by spraying a solution for causing a Fenton reaction into the gas phase, and a step for decomposing the gaseous substance and the particulate substance using the aerosol.

Description

Method and apparatus for decomposing gaseous and particulate matter in gas phase

The present invention relates to a method and apparatus for decomposing gaseous substances and particulate matter in the gas phase.

A method using ozone or plasma is known as a method for decomposing gaseous substances and particulate matter in the gas phase. These techniques are useful as techniques for decomposing the above substances, but they have low processing capacity and have problems in processing the generated ozone. Therefore, it is currently used in a limited space where the air is relatively clean, and its applicability in a place with a high concentration of pollutants is low.

Also known is a method of removing gaseous substances and particulate matter in the gas phase by collecting them with filters or adsorbents. The above method is effective in that it can temporarily collect gaseous substances and particulate matter in the gas phase and reduce their concentrations, but it involves the disposal of dirty filters and adsorbents. , the cost of maintenance is high, and the load on the environment is large. A method that is inexpensive, requires low maintenance frequency, and can efficiently decompose the above substances has not yet been established.

On the other hand, the method of using the Fenton reaction as a material decomposition method in the liquid phase has traditionally attracted attention as an inexpensive and practical means. However, in the liquid phase treatment, since the treated water is circulated from the viewpoint of cost reduction, there are problems such as coloration of the solution and sedimentation of sludge in the liquid phase. In addition, since divalent iron is used as a reaction source, it is necessary to devise ways to promote the reduction of iron from trivalent to divalent iron, as described in Patent Document 1, for example. Although there are few examples of applying the Fenton reaction to the gas phase, for example, Patent Document 2 describes supplying an aqueous solution containing divalent iron ions in an atomized state into air containing hydrogen peroxide. there is

Japanese Patent No. 6202770 Japanese Patent No. 6039834

However, in the method disclosed in Patent Document 2, since an aqueous solution containing iron ions is sprayed into the air containing hydrogen peroxide, it is difficult to control the concentration of hydrogen peroxide taken into the aerosol particles containing iron ions. be. Therefore, it is extremely difficult to control the Fenton reaction, and gaseous substances and particulate matter in the gas phase cannot be decomposed with sufficient efficiency.

An object of the present invention is to provide a method and apparatus capable of efficiently decomposing gaseous substances and particulate matter in the gas phase.

The present invention includes the following embodiments.

[1] A method for decomposing gaseous substances and particulate matter in a gas phase, comprising:
spraying a solution that causes a Fenton reaction into the gas phase to generate an aerosol;
decomposing the gaseous substance and the particulate matter with the aerosol;
method including.

[2] The method according to [1], wherein the aerosol particles contained in the aerosol do not contain coarse particles having a particle size of 40 μm or more in number particle size distribution and have a peak in the range of 1 to 10 μm. .

[3] The method according to [1] or [2], wherein the method for spraying the solution that causes the Fenton reaction into the gas phase is a two-fluid nozzle method, an ultrasonic atomization method, or a surface acoustic wave method.

[4] The method according to any one of [1] to [3], further comprising the step of forming fine bubbles in the solution that causes the Fenton reaction or its raw material solution.

[5] The method according to [4], wherein the fine bubble generation method is at least one method selected from the group consisting of a pressurized dissolution method, an ultrasonic method, a swirling flow method, and an ejector method.

[6] The method according to [4] or [5], wherein the number particle size distribution of the fine bubbles has a peak at 300 nm or less.

[7] The method according to any one of [4] to [6], wherein the number concentration of the fine bubbles in the solution causing the Fenton reaction or its raw material solution is 1×10 ⁷ /cc or more.

[8] The method according to any one of [1] to [7], wherein the solution causing the Fenton reaction contains iron ions and hydrogen peroxide.

[9] The method according to [8], wherein the iron ion concentration in the solution causing the Fenton reaction is 51 to 250 mg/L.

[10] The method according to [8] or [9], wherein the concentration of the hydrogen peroxide in the solution causing the Fenton reaction is 1000 to 10000 mg/L.

[11] The method according to any one of [8] to [10], wherein the solution causing the Fenton reaction further contains a pH adjuster.

[12] The method according to [11], wherein the pH adjuster is at least one compound selected from the group consisting of citric acid and oxalic acid.

[13] The method according to any one of [1] to [12], wherein the pH of the solution causing the Fenton reaction is 3 or more and less than 5.

[14] The method according to any one of [1] to [13], wherein the gaseous substance and the particulate matter are tobacco smoke.

[15] of [1] to [14], wherein the solution that causes the Fenton reaction further contains at least one transition metal ion selected from the group consisting of copper ions, zinc ions, cobalt ions, manganese ions and nickel ions. Any method described.

[16] a chamber containing gaseous matter and particulate matter in an internal gas phase;
a tank holding a plurality of raw material liquids that are raw materials of the solution that causes the Fenton reaction;
a sprayer for spraying a solution that causes a Fenton reaction obtained by mixing the plurality of raw material liquids into the gas phase inside the chamber;
An apparatus for decomposing gaseous and particulate matter in the gas phase, comprising:

[17] The apparatus according to [16], further comprising a fine bubble generator connected to the tank and forming fine bubbles in at least one of the raw material liquids.

[18] The apparatus of [16] or [17], wherein the gaseous matter and the particulate matter are tobacco smoke.

According to the present invention, it is possible to provide a method and apparatus capable of efficiently decomposing gaseous substances and particulate matter in the gas phase.

It is a schematic diagram showing an example of the decomposition apparatus according to the present embodiment. FIG. 2 is a diagram showing the number particle size distribution of aerosol particles in Reference Examples 1 and 2; 1 is a photograph of aerosol particles in Reference Examples 1 and 2 taken with a high-speed camera.

[Method for Decomposing Gaseous Matter and Particulate Matter in Gas Phase]
A method for decomposing gaseous substances and particulate matter in a gas phase according to the present embodiment includes the following steps. A step of spraying a solution that causes a Fenton reaction into the gas phase to generate an aerosol (hereinafter also referred to as an aerosol generating step); Also called a process).

In the method according to the present embodiment, since the solution that causes the Fenton reaction (hereinafter also referred to as the Fenton reaction solution) is sprayed into the gas phase containing the gaseous substance and the particulate matter, the gaseous substance in the gas phase is efficiently It can decompose matter and particulate matter. It is believed that spraying the Fenton reaction solution makes it easier to control the concentrations of iron ions and hydrogen peroxide in the aerosol particles, and also accelerates the Fenton reaction due to the fluid cavitation effect. As will be described later, in the method according to the present embodiment, by further optimizing the conditions of the Fenton reaction solution for spraying, it is possible to suppress the coloring and sludge formation of the solution and further increase the decomposition efficiency. Specifically, by using a pH adjuster that forms a complex with iron ions, and by adjusting the concentrations of iron ions and hydrogen peroxide, the formation of sludge can be particularly suppressed. In addition, from the viewpoint of improving the decomposition efficiency, there is an optimum pH of the Fenton reaction solution, and when the pH is 3 or more and less than 5, the decomposition efficiency can be maximized, while the solution coloring and sludge formation can be suppressed. Furthermore, the atomization conditions of the Fenton reaction solution are related to the particle size distribution and number concentration of the aerosol particles, and the decomposition efficiency can be further enhanced by controlling the particle size conditions.

In addition to the aerosol generation step and the decomposition step, the method according to the present embodiment includes, for example, a step of forming fine bubbles in a solution that causes a Fenton reaction or its raw material solution (hereinafter also referred to as a fine bubble formation step). may include The gaseous substances and particulate substances contained in the gas phase are not particularly limited, but may be, for example, tobacco smoke, exhaust smoke or gases containing industrially generated organic substances, and the like. The method according to this embodiment is particularly effective for decomposing tobacco smoke in the gas phase. Examples of gaseous substances contained in tobacco smoke include aldehydes such as formaldehyde and acetaldehyde, and volatile organic compounds (VOCs) such as benzene. Particulate matter contained in tobacco smoke includes, for example, polycyclic aromatic hydrocarbons and fatty acids, which are oily substances.

(Aerosol generation process)
In this step, the Fenton reaction solution is sprayed into a gas phase in which gaseous substances and particulate substances are present to generate an aerosol. The Fenton reaction solution is a solution capable of generating hydroxyl radicals from hydrogen peroxide using iron as a catalyst, and can contain iron ions and hydrogen peroxide. The iron ions can be, for example, iron ions derived from iron sulfate, iron chloride, iron nitrate, iron oxide, and the like. The hydrogen peroxide can be hydrogen peroxide derived from aqueous hydrogen peroxide, sodium percarbonate, and the like. Examples of the solvent for the Fenton reaction solution include water and ethanol, with water being preferred. The quality of water is not particularly limited, and a sufficient effect can be expected even with purified water or ordinary tap water.

The concentration of iron ions in the Fenton reaction solution is preferably 51 mg/L or more and less than 500 mg/L. When the concentration is 51 mg/L or more, higher decomposition efficiency can be obtained. Further, when the concentration is less than 500 mg/L, coloration of the solution and generation of sludge can be sufficiently suppressed. The concentration is more preferably 60 mg/L or more and 250 mg/L or less, more preferably 70 mg/L or more and less than 200 mg/L. The concentration of iron ions in the Fenton reaction solution can be measured by ion chromatography or the like.

The concentration of hydrogen peroxide in the Fenton reaction solution is preferably 1000 mg/L or more and 10000 mg/L or less. When the concentration is 1000 mg/L or more, higher decomposition efficiency can be obtained, and coloration of the solution and formation of sludge can be suppressed. Further, when the concentration is 10000 mg/L or less, the decomposition rate can be improved and maintained without significantly increasing sludge formation. At an excessive concentration of hydrogen peroxide, the generated radicals are scavenged by the hydrogen peroxide, so it is desirable to operate within this concentration range. The concentration is more preferably 5000 mg/L or more and 10000 mg/L or less, more preferably 7500 mg/L or more and 10000 mg/L or less. The concentration of hydrogen peroxide in the Fenton reaction solution can be measured with a hydrogen peroxide concentration meter or the like.

The Fenton reaction solution preferably further contains a pH adjuster. By including the pH adjuster in the Fenton reaction solution, it is possible to further suppress the coloring of the solution and the generation of sludge. As the pH adjuster, a pH adjuster capable of forming a complex with iron ions is preferable, and examples thereof include citric acid and oxalic acid. Among these, citric acid is more preferable from the viewpoint of suppressing coloration of the solution and generation of sludge and having less effect on health. These pH adjusters may be used alone or in combination of two or more. The amount of the pH adjuster contained in the Fenton reaction solution can be appropriately selected so as to achieve a preferable pH range of the Fenton reaction solution, which will be described later.

From the viewpoint of further improving the decomposition efficiency, the Fenton reaction solution further contains at least one transition metal ion (other than iron ions) selected from the group consisting of copper ions, zinc ions, cobalt ions, manganese ions and nickel ions. can be done. The copper ions can be, for example, copper ions derived from copper sulfate, copper nitrate, copper oxide, and the like. The zinc ions can be, for example, zinc ions derived from zinc sulfate and the like. Cobalt ions can be, for example, cobalt ions derived from cobalt chloride, cobalt nitrate, and the like. The manganese ions can be, for example, manganese ions derived from manganese sulfate and the like. The nickel ions can be, for example, nickel ions derived from nickel chloride and the like. When the Fenton reaction solution contains the transition metal ion, the concentration of the transition metal ion in the Fenton reaction solution is preferably 0.1 mg/L or more and less than 500 mg/L, more preferably 51 mg/L or more and less than 500 mg/L. The concentration of the transition metal ions in the Fenton reaction solution can be measured by an ion chromatograph or an inductively coupled plasma atomic emission spectrometer.

The Fenton reaction solution contains, in addition to iron ions, hydrogen peroxide, a pH adjuster, the transition metal ions (other than iron ions), and a solvent, for example, a reduction accelerator for promoting reduction to divalent iron and oxidation of divalent iron. Antioxidants and the like can be included to prevent

The pH of the Fenton reaction solution is preferably 3 or more and less than 5. When the pH is 3 or more, higher decomposition efficiency can be obtained. Further, when the pH is less than 5, coloring of the solution and generation of sludge can be further suppressed. The pH is more preferably 3 or more and less than 4, more preferably 3.5 or more and less than 4. The pH of the Fenton reaction solution is a value measured using a pH meter (Toa DKK, HM-41).

The aerosol generated by spraying the Fenton reaction solution contains aerosol particles that exist in the form of particles and gasified components that exist around the aerosol particles. In the method according to the present embodiment, from the viewpoint of further improving the decomposition efficiency, the aerosol particles contained in the generated aerosol do not contain coarse particles having a particle size of 40 μm or more in the number particle size distribution, and have a particle size of 1 to 10 μm. It is preferable to have a peak within the range of . In the number particle size distribution, the aerosol particles do not contain coarse particles having a particle size of 40 μm or more, and have a peak in the range of 1 to 10 μm, so that a large amount of radicals are generated instantaneously, and the decomposition efficiency is higher. expected to improve. This is believed to be due to the synergistic effect of fluid cavitation and cavity collapse during spraying and the Fenton reaction. In addition, since aerosol particles within this range are less susceptible to the effects of gravity and can stably float in space, it is expected that the probability and time of contact with aerosol particles will be improved. In order to make aerosol particles with a very fine number particle size distribution, for example, it is necessary to apply liquid pressure and air pressure above a certain level, and this pressure and the pressure difference up to the atomization cause fluid cavitation and cavity collapse. and is expected to further accelerate the Fenton reaction. The peak particle size of the aerosol particles is more preferably 2 to 10 μm, even more preferably 2 to 5 μm. Here, the peak in the number particle size distribution refers to the mode (mode size).

It should be noted that it can be confirmed by the following method that the aerosol particles contained in the aerosol do not contain coarse particles having a particle size of 40 μm or more in the number particle size distribution and have a peak within the range of 1 to 10 μm. The number particle size distribution of the aerosol particles is measured with a sensor HP2070 using a particle size distribution analyzer welas (PALAS, digital 2000). The number particle size distribution is measured at a point 50 cm away from the tip of the spray nozzle in the horizontal direction.

The method for spraying the Fenton reaction solution into the gas phase is preferably a two-fluid nozzle method, an ultrasonic atomization method, or a surface acoustic wave method. By adopting these methods, the particle size of the aerosol particles contained in the aerosol can be easily controlled within the above range. In particular, the two-fluid nozzle system is more preferable from the viewpoint of maximizing the fluid cavitation effect. In the case of the two-fluid nozzle system, the pressure in the tank holding the Fenton reaction solution, which supplies the Fenton reaction solution to the nozzle, is preferably 0.1 to 0.3 MPa. Also, the spray pressure is preferably 0.1 to 0.4 MPa, more preferably 0.21 to 0.4 MPa. Examples of the gas to be introduced into the nozzle include air and nitrogen. In addition, the raw material solution containing iron ions and the raw material solution containing hydrogen peroxide are held separately in the tank, and the two are mixed just before the nozzle, and the Fenton reaction solution can be sprayed from the nozzle. The shape of the spray nozzle is not particularly limited, and one that can efficiently disperse the aerosol particles is desirable.

The spray rate for spraying the Fenton reaction solution into the gas phase is not particularly limited, but can be, for example, 0.01 to 10 L/hour. Spraying may be continuous or intermittent spraying with certain sprays and pauses. The spray speed here is the value for continuous spray.

(Decomposition process)
In this step, the gaseous substances and particulate matter in the gas phase are decomposed by the aerosol generated in the aerosol generating step. When the Fenton reaction solution is sprayed and an aerosol is generated, radical generation is accelerated, and gaseous substances and particulate matter in the gas phase in contact with the radicals are instantaneously decomposed. In addition, since the Fenton reaction proceeds within the aerosol particles in the aerosol and radicals are further generated, gaseous substances and particulate substances that come into contact with the aerosol particles floating in the gas phase after spraying, and are taken into the aerosol particles Gaseous and particulate matter are also decomposed. Therefore, the method according to the present embodiment can efficiently decompose gaseous substances and particulate matter in the gas phase. In particular, the method according to this embodiment can efficiently decompose tobacco smoke in the gas phase (air).

The total concentration of gaseous substances and particulate matter in the gas phase is not particularly limited, but when the gaseous matter and particulate matter are tobacco smoke, the concentration of tobacco smoke is, for example, 0.1 in mass concentration of particles. It can be ~30 mg/m ³ . Although the temperature of the gas phase is not particularly limited, it can be, for example, 10 to 30° C. From the viewpoint of acceleration of the Fenton reaction, the higher the temperature, the higher the reaction rate, so a high effect can be expected.

(Fine bubble forming step)
The method according to this embodiment preferably further includes a fine bubble forming step of forming fine bubbles in the Fenton reaction solution or its raw material solution. If the Fenton reaction solution to be sprayed contains fine bubbles, the decomposition efficiency is further improved. This is probably because the Fenton reaction solution originally contains fine air bubbles, and the air bubbles act as the nuclei of the cavities, resulting in a better fluid cavitation effect. Furthermore, due to the physical detergency of fine bubbles, the sprayer, the tank holding the Fenton reaction solution or its raw material liquid, and the flow path connecting the sprayer and the tank through which the Fenton reaction solution or its raw material liquid passes are dirty. becomes difficult to adhere, and more stable spraying can be achieved. The fine bubble formation step may be performed before the aerosol generation step, or may be performed during the aerosol generation step. The raw material solution of the Fenton reaction solution is a solution that can prepare the Fenton reaction solution by mixing or the like, and can be, for example, a solution containing iron ions, a solution containing hydrogen peroxide, or the like. When there are a plurality of raw material liquids, the fine bubble forming step may be performed for one raw material liquid, or the fine bubble forming step may be performed for two or more raw material liquids.

The fine bubble generation method is not particularly limited, but is selected from the group consisting of the pressurized dissolution method, the ultrasonic method, the swirl flow method, and the ejector method from the viewpoint of the ease of the generation method and the size and concentration of the fine bubbles to be generated. is preferably at least one type of method.

The fine bubbles preferably have a peak at 300 nm or less in the number particle size distribution. When the fine bubbles have a peak at 300 nm or less in the number particle size distribution, they can remain in the liquid as bubbles for a longer period of time, and can further promote the generation of radicals. The fine bubbles more preferably have a number particle size distribution peak within the range of 20 to 300 nm, more preferably within the range of 50 to 200 nm. The number particle size distribution of fine bubbles can be measured using Nanosite (Malvern Panalytical, NS300) that measures and analyzes the Brownian motion of nanoparticles in liquid.

The number concentration of fine bubbles in the Fenton reaction solution or its raw material solution is preferably 1×10 ⁷ /cc or more. When the number concentration is 1×10 ⁷ /cc or more, the decomposition efficiency is further improved. The number concentration is more preferably 5×10 ⁷ to 1×10 ⁹ pieces/cc, more preferably 1×10 ⁸ to 1×10 ⁹ pieces/cc. The number concentration of fine bubbles can be measured using the nanosite described above.

[Device for decomposing gaseous and particulate matter in gas phase]
An apparatus for decomposing gaseous substances and particulate matter in a gas phase according to the present embodiment has the following configuration. A chamber containing a gaseous substance and particulate matter in an internal gas phase; a tank holding a plurality of raw material liquids that are raw materials of a solution that causes a Fenton reaction; and a Fenton reaction that is obtained by mixing the plurality of raw material liquids. A nebulizer for nebulizing a solution into the gas phase inside the chamber. The decomposition apparatus according to this embodiment can suitably perform the decomposition method according to this embodiment described above, and can efficiently decompose gaseous substances and particulate matter in the gas phase. It is preferable that the decomposition apparatus according to the present embodiment further includes a fine bubble generator that is connected to the tank and that forms fine bubbles in at least one of the raw material liquids, from the viewpoint of further improving the decomposition efficiency. . Further, a filter, an activated carbon filling layer, or the like may be provided at the exhaust outlet for capturing excess hydrogen peroxide or the like after decomposition. The decomposing device according to this embodiment is particularly effective for decomposing tobacco smoke in the gas phase.

Fig. 1 shows an example of a disassembling device according to this embodiment. A decomposition apparatus 1 shown in FIG. 1 holds a chamber 2 containing tobacco smoke 6, which is a gaseous substance and particulate matter, in an internal gas phase, and

raw material liquids

5a and 5b, which are raw materials of a solution that causes a Fenton reaction. and a sprayer 4 for spraying into the gas phase inside the chamber 2 a solution that causes the Fenton reaction obtained by mixing the

raw material liquids

5a and 5b. The chamber 2 includes an introduction portion 9 that introduces the tobacco smoke 6 into the chamber 2 , and an exhaust portion 10 that exhausts the gas obtained by decomposing the tobacco smoke 6 from the chamber 2 to the outside. The discharge section 10 is provided with a filter 12 and a fan 13 . The

raw material liquids

5a and 5b in the tank 3 are mixed and supplied to the two-fluid nozzle type sprayer 4, and sprayed into the chamber 2 together with the compressed air 11 to generate the aerosol 7. FIG. The aerosol 7 contains aerosol particles 8 which break up the tobacco smoke 6 in the chamber 2 . Cigarette smoke 6 that has not been decomposed in chamber 2 is trapped in filter 12 together with aerosol particles 8 and decomposed in filter 12 . Therefore, the tobacco smoke 6 is efficiently decomposed.

Although not shown in FIG. 1, the decomposition device 1 can further include a fine bubble generator that forms fine bubbles in at least one of the

raw material liquids

5a and 5b in the tank 3. Fine bubbles may be formed by the fine bubble generator before mixing the

raw material liquids

5a and 5b and spraying, or during spraying.

Hereinafter, the present embodiment will be described in detail with examples, but the present embodiment is not limited to these examples.

[Reference example 1]
Ultrapure water in which 10.2 mg/L of methylene blue was dissolved was prepared in a 1 L beaker. Iron sulfate heptahydrate (Fuji Film Wako Pure Chemical Co., Ltd., 094-01082) was added to the solution so that the iron ion concentration was 2 mg/L. In addition, sulfuric acid (Fuji Film Wako Pure Chemical Industries, Ltd., 198-09595) was used to adjust the pH of the solution to 3.0. Thus, a raw material liquid A was prepared. Next, in a new beaker, hydrogen peroxide solution (Fujifilm Wako Pure Chemical Co., Ltd., 081-04215) is added to ultrapure water so that the concentration of hydrogen peroxide is 1580 mg / L, and the pH is adjusted using sulfuric acid. was similarly adjusted to 3.0. Thus, a raw material liquid B was prepared. Both beakers were placed in a tank of a two-fluid nozzle type two-fluid spray cart IIIX (Spraying Co., SCU3XVA-777). By pressurizing the inside of the tank with compressed air, the raw material liquids A and B in both beakers are pushed out, and immediately before spraying, the raw material liquids A and B are mixed in equal amounts to prepare a Fenton reaction solution, which is then sprayed at the nozzle. The solution was mixed with compressed air so that it could be atomized. The pressure in the tank was 0.2 MPa, and the spray pressure was 0.2 MPa. A two-fluid automatic spray gun (Spraying Co., 10535-1/4J-SS) was used for spraying, and a flat type nozzle cap (Spraying Co., PF1650DF-SS) was used.

(Measurement of number particle size distribution, etc. of aerosol particles)
The number particle size distribution of the aerosol particles contained in the aerosol generated by nebulization was measured with a sensor HP2070 using a particle size distribution analyzer welas (PALAS, digital 2000). The number particle size distribution was measured at a point 50 cm away from the tip of the spray nozzle in the horizontal direction. The results are shown in FIG.

In addition, since the measurable range of the particle size distribution analyzer used for this measurement is limited (maximum particle size: 40 μm), coarse particles having a particle size exceeding 40 μm were confirmed using a high-speed camera. . A high-speed camera (trade name: VW-9000 high speed microscope, Keyence Corporation) was used as the high-speed camera. The photographing conditions were shutter speed: 1/30000 seconds, number of frames: 8000 fps, number of pixels: 640×240 pixels. A photograph taken with a high-speed camera is shown in FIG. The particles shown in the figure indicate the presence of large particles that can be imaged by the camera. By changing the sensor of the particle size distribution analyzer, it is possible to measure particles exceeding 40 μm.

(Evaluation of decomposition performance)
The sprayed Fenton reaction solution is colored by methylene blue, but as the Fenton reaction progresses, the methylene blue is decomposed and the color is reduced. The decomposition performance was evaluated by evaluating the attenuation of this color. Specifically, the Fenton reaction solution that had settled after spraying was collected in a 1 L graduated cylinder, and the absorbance of the solution was measured 3 minutes after spraying. An absorbance photometer (Shimadzu Corporation, UV-1800) was used to measure the absorbance, and the reduction rate of methylene blue was evaluated by measuring absorbance attenuation at a wavelength of 664 nm. A smaller value of the reduction rate indicates that the methylene blue is more decomposed and the decomposition efficiency is higher. Table 1 shows the results.

[Reference example 2]
The procedure was carried out in the same manner as in Reference Example 1 except that the spray pressure was changed to 0.3 MPa, the number particle size distribution of the aerosol particles and the like were measured, and the decomposition performance was evaluated. The results are shown in FIGS. 2, 3 and Table 1.

[Reference example 3]
In the preparation of raw material solutions A and B, before adding iron sulfate heptahydrate or hydrogen peroxide solution, a pressurized dissolution type fine bubble generator (OM4-MDG-045, Aura Tech Co., Ltd.) was used for 1 hour. The decomposition performance was evaluated in the same manner as in Reference Example 1, except that fine bubbles were continuously generated. Table 1 shows the results. The fine bubbles had a peak at 81.6 nm in the number particle size distribution. The number concentration of fine bubbles was 7.23×10 ⁷ /cc.

[Reference Example 4]
In the preparation of raw material liquid A, iron sulfate heptahydrate and sulfuric acid were not added. Further, in the preparation of the raw material liquid B, neither hydrogen peroxide solution nor sulfuric acid was added. Further, the spray pressure was set to 0 MPa (no compressed air was introduced into the nozzle, the Fenton reaction solution only passed through the nozzle and was not sprayed). Other than these, it was carried out in the same manner as in Reference Example 3, and the decomposition performance was evaluated. Table 1 shows the results.

[Reference Example 5]
In the preparation of raw material liquid A, iron sulfate heptahydrate and sulfuric acid were not added. Further, in the preparation of the raw material liquid B, neither hydrogen peroxide solution nor sulfuric acid was added. Other than these, it was carried out in the same manner as in Reference Example 3, and the decomposition performance was evaluated. Table 1 shows the results.

[Reference Example 6]
The decomposition performance was evaluated in the same manner as in Reference Example 1, except that the spray pressure was 0 MPa (no compressed air was introduced into the nozzle, the Fenton reaction solution only passed through the nozzle and was not sprayed). Table 1 shows the results.

From Table 1, in Reference Examples 1 to 3 in which the Fenton reaction solution was sprayed, the reduction rate was smaller than in Reference Examples 4 to 6 in which the Fenton reaction solution was not sprayed. Do you get it. Further, from FIGS. 2 and 3, in Reference Example 2 sprayed at a high pressure (0.3 MPa), the aerosol particles do not contain coarse particles having a particle size of 40 μm or more in the number particle size distribution, and have a particle size of 1 to 10 μm. It was found to have a peak within the range of . When comparing Reference Example 1 sprayed at low pressure (0.2 MPa) and Reference Example 2 sprayed at high pressure (0.3 MPa), Reference Example 2 had a smaller reduction rate value and higher decomposition efficiency. . By spraying at high pressure, the aerosol particles have a very fine number particle size distribution, and the value of the reduction rate of methylene blue tends to decrease at the moment of spraying. Presumably produced in large quantities. This is believed to be due to the synergistic effect of fluid cavitation and cavity collapse during spraying and the Fenton reaction. Furthermore, in Reference Example 3, in which the sprayed Fenton reaction solution contained fine bubbles, a lower reduction rate value (higher decomposition efficiency) was obtained. This is probably because the solution originally contained fine air bubbles, and the air bubbles acted as cores of the cavities, resulting in a higher effect.

[Reference Example 7]
One tobacco (Mobius Super Light) was naturally combusted in a glass tube after adjusting the flow rate so that the linear velocity was 0.1 m/s. Cigarette smoke generated was collected with a Cambridge pad (Borgwaldt, 44 mmφ) and an impinger containing 100 ml of ultrapure water. After the tobacco smoke was collected on the Cambridge pad, it was shaken and extracted with 100 ml of ultrapure water added to an impinger, followed by syringe filtration to obtain a tobacco smoke solution. After that, iron sulfate heptahydrate in an amount that makes the iron ion concentration 10 mg/L, hydrogen peroxide water in an amount that makes the hydrogen peroxide concentration 100 mg/L, and an amount that makes the pH 4.0 are added to the cigarette smoke solution. of citric acid (Fuji Film Wako Pure Chemical Co., Ltd., 030-05525) was added and allowed to stand for 24 hours. After standing still, the coloration of the solution and the presence or absence of sludge formation were visually observed. In addition, TOC (Total Organic Carbon) measurement was performed using a total organic carbon meter (Shimadzu Corporation, TOC-L CPN) to evaluate the decomposition rate of tobacco smoke solution (TOC decomposition rate). Here, the decomposition rate means the attenuation rate of the TOC concentration before and after addition of iron sulfate heptahydrate and hydrogen peroxide solution to the cigarette smoke solution. Table 2 shows the results. When the Fenton reaction solution is sprayed, the solution floats in space as very small aerosol particles, but since the aerosol particles exist as droplets, it is speculated that the same reaction as in the liquid phase occurs. be done. Therefore, this test was conducted in the liquid phase.

[Reference Examples 8 to 30]
Reference Example 7 except that the amounts of iron sulfate heptahydrate, hydrogen peroxide solution, and citric acid added were changed so that the iron ion concentration, hydrogen peroxide concentration, and pH were the values shown in Table 2. was carried out in the same manner as in , and the presence or absence of coloration of the solution and sludge formation was observed, and the TOC decomposition rate was evaluated. Table 2 shows the results.

From Table 2, no coloration of the solution and formation of sludge were observed, and the TOC decomposition rate was high. A condition of 3 or more and less than 5 was found to be the optimum condition for the Fenton reaction solution in aerosol spraying.

[Example 1]
Iron sulfate heptahydrate (Fuji Film Wako Pure Chemical Co., Ltd., 094-01082) was added to the ultrapure water so that the iron ion concentration was 200 mg/L. The pH of the solution was adjusted to 3.0 using citric acid (Fuji Film Wako Pure Chemical Co., Ltd., 030-05525). Thus, a raw material liquid A was prepared. Separately from the raw material solution A, a hydrogen peroxide solution (Fujifilm Wako Pure Chemical Co., Ltd., 081-04215) was added to ultrapure water so that the concentration of hydrogen peroxide was 10000 mg / L, and the pH was adjusted using citric acid. was similarly adjusted to 3.0. Thus, a raw material liquid B was prepared. In the preparation of raw material solutions A and B, before adding iron sulfate heptahydrate or hydrogen peroxide solution, fine bubbles were generated for 1 hour using a pressurized dissolution type fine bubble generator (LE3FS, Living Energy). kept happening. Fine bubbles had a peak at 95.1 nm in number particle size distribution. The number concentration of fine bubbles was 2.07×10 ⁸ /cc. The obtained raw material liquids A and B were placed in the tank of a two-fluid atomizer spray cart IIIX (Spraying Co., SCU3XVA-777). By pressurizing the inside of the tank with compressed air, the raw material liquids A and B are extruded, and immediately before spraying, the raw material liquids A and B are mixed in equal amounts to prepare a Fenton reaction solution, and the solution and the compressed air are sprayed at the nozzle. and can be sprayed by mixing. The pressure in the tank was 0.2 MPa, and the spray pressure was 0.25 MPa. A two-fluid automatic spray gun (Spraying Co., 10535-1/4J-SS) was used for spraying. A flat type nozzle cap was used, but a small amount type nozzle cap (PF1050DF-SS by Spraying Co.) was used in order to reduce the amount of spray.

Eight cigarettes (Mobius Super Light) were spontaneously burned at the same time in an indoor space of about 45 m ³ to create a space filled with tobacco sidestream smoke. After that, the Fenton reaction solution was sprayed into the space by the two-fluid spray device. TVOC concentrations were measured by a TVOC (Total Volatile Organic Compounds) meter (RAE systems, ppbRAE 3000+) for about 1 hour. The TVOC reduction rate was calculated from the difference between the TVOC concentration when the Fenton's reaction solution was sprayed and the TVOC concentration after 1 hour of spontaneous combustion without spraying the Fenton's reaction solution. Table 3 shows the results.

[Example 2]
The TVOC concentration was measured in the same manner as in Example 1, except that the pH of the raw material liquids A and B was changed to 4.0. Table 3 shows the results.

[Example 3]
The TVOC concentration was measured in the same manner as in Example 1, except that the pH of the raw material liquids A and B was changed to 5.0. Table 3 shows the results.

[Example 4]
Example 1 was repeated except that NaOH was used instead of citric acid in the preparation of raw material solutions A and B, and the pH of raw material solutions A and B was changed to 6.0, and the TVOC concentration was measured. . Table 3 shows the results.

[Comparative Example 1]
The TVOC concentration was measured in the same manner as in Example 1, except that ultrapure water was used as raw material solutions A and B (no iron sulfate heptahydrate, hydrogen peroxide solution, or citric acid was added). Table 3 shows the results.

[Reference Example 31]
The TVOC concentration was measured in the same manner as in Example 1, except that nothing was sprayed into the space filled with tobacco sidestream smoke. Table 3 shows the results.

From Table 3, it was found that Examples 1 to 4, in which tobacco smoke was decomposed by the method according to the present embodiment, exhibited a significant TVOC reduction rate and efficiently decomposed tobacco smoke. Especially when the pH of the Fenton reaction solution was around 3 to 4, a higher reduction rate was obtained. Based on the results of Reference Examples 28 to 30 in which the coloration of the solution and the formation of sludge were examined, it was found that the pH is preferably 3 or more and less than 5, and particularly preferably 3 or more and 4 or less.

1 decomposition device 2 chamber 3 tank 4

atomizer

5a, 5b raw material liquid 6 cigarette smoke 7 aerosol 8 aerosol particles 9 introduction part 10 discharge part 11 compressed air 12 filter 13 fan

Claims

A method for decomposing gaseous and particulate matter in a gas phase, comprising:
spraying a solution that causes a Fenton reaction into the gas phase to generate an aerosol;
decomposing the gaseous substance and the particulate matter with the aerosol;
method including.
The method according to claim 1, wherein the aerosol particles contained in the aerosol do not contain coarse particles having a particle size of 40 μm or more and have a peak in the range of 1 to 10 μm in the number particle size distribution.
3. The method according to claim 1 or 2, wherein the method of spraying the solution that causes the Fenton reaction into the gas phase is a two-fluid nozzle method, an ultrasonic atomization method, or a surface acoustic wave method.
The method according to any one of claims 1 to 3, further comprising a step of forming fine bubbles in the solution or raw material liquid for causing the Fenton reaction.
The method according to claim 4, wherein the fine bubble generation method is at least one method selected from the group consisting of a pressure dissolution method, an ultrasonic method, a swirling flow method, and an ejector method.
The method according to claim 4 or 5, wherein the fine bubbles have a number particle size distribution peak at 300 nm or less.
The method according to any one of claims 4 to 6, wherein the number concentration of the fine bubbles in the solution causing the Fenton reaction or its raw material solution is 1 x 107 /cc or more.
The method according to any one of claims 1 to 7, wherein the solution causing the Fenton reaction contains iron ions and hydrogen peroxide.
The method according to claim 8, wherein the iron ion concentration in the solution causing the Fenton reaction is 51 to 250 mg/L.
The method according to claim 8 or 9, wherein the concentration of the hydrogen peroxide in the solution causing the Fenton reaction is 1000-10000 mg/L.
The method according to any one of claims 8 to 10, wherein the solution causing the Fenton reaction further contains a pH adjuster.
The method according to claim 11, wherein the pH adjuster is at least one compound selected from the group consisting of citric acid and oxalic acid.
The method according to any one of claims 1 to 12, wherein the pH of the solution causing the Fenton reaction is 3 or more and less than 5.
The method according to any one of claims 1 to 13, wherein the gaseous substance and the particulate matter are tobacco smoke.
The solution according to any one of claims 1 to 14, wherein the solution that causes the Fenton reaction further contains at least one transition metal ion selected from the group consisting of copper ions, zinc ions, cobalt ions, manganese ions and nickel ions. described method.
a chamber containing gaseous matter and particulate matter in an internal gas phase;
a tank holding a plurality of raw material liquids that are raw materials of the solution that causes the Fenton reaction;
a sprayer for spraying a solution that causes a Fenton reaction obtained by mixing the plurality of raw material liquids into the gas phase inside the chamber;
An apparatus for decomposing gaseous and particulate matter in the gas phase, comprising:
The apparatus according to claim 16, further comprising a fine bubble generator connected to said tank and forming fine bubbles in at least one of said raw material liquids.
The device according to claim 16 or 17, wherein said gaseous matter and said particulate matter are tobacco smoke.