JP2005111355A - Photocatalyst, photocatalyst-carried ceramic porous body, decomposition cleaning method for toxic substance and gas cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst capable of quickly decomposing/cleaning a toxic substance. <P>SOLUTION: In an immersion step 1, a ceramic porous body with a void diameter of 2-3 mm comprising cordierite is immersed into a sol solution of titanium oxide and is pulled up from the sol solution. Thereafter, in a removal step 2, the sol solution remaining in the pore is removed by a blower, and in a calcination step 3, the ceramic porous body removed of the sol solution in the pore is calcined at 500°C to obtain the titanium oxide porous body. In a second immersion step 4, the titanium oxide porous body is immersed into a basic water having pH adjusted to 9.6 for 1 hour, and in a drying step 5, the titanium oxide porous body after the immersion is dried at 110°C for 2 hours to complete the production of the titanium oxide porous body with excellent decomposition cleaning speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photocatalyst that decomposes and purifies harmful substances, a photocatalyst-supported ceramic porous body, a method for decomposing and purifying harmful substances, and a gas purification apparatus.

  When a photocatalyst represented by titanium oxide or the like is irradiated with light having energy higher than the band gap of the photocatalyst, holes and electrons are generated inside the photocatalyst. These holes and electrons diffuse to the surface of the photocatalyst and react with a substance adsorbed on the surface of the photocatalyst or a substance existing in the vicinity of the surface of the photocatalyst. Many air purification devices using the properties of this photocatalyst have been commercialized, and many patent applications have been filed.

  For example, FIG. 6 is a plan view of an air cleaner using ozone and a photocatalyst together. A filter member, an ozone generation unit, a photocatalyst device, and an activated carbon unit in order from the upstream to the downstream of the flow path of the air that is the fluid to be treated, the photocatalyst device forming a flow path for the air, and the interior of the case member A photocatalytic filter in which a photocatalytic functional layer is supported on a substrate having a large number of holes, and an ultraviolet irradiation means for irradiating the photocatalytic filter, and the entire amount of air to be processed passes through the photocatalytic filter. A photocatalytic filter is disposed so as to flow (see, for example, Patent Document 1).

  FIG. 7 is a vertical cross-sectional view of an air purifying apparatus using an adsorbent containing at least one of activated carbon and zeolite and a photocatalyst. A cylindrical deodorizing filter including a photocatalyst, and an excitation light source disposed in the vicinity of the deodorizing filter on the upstream side of the deodorizing filter, and the deodorizing filter is rotated so that the irradiation position of the light from the excitation light source changes. Therefore, the gas adsorbed on the entire deodorizing filter can be processed and decomposed, so that the regeneration rate of the deodorizing filter can be improved and the initial excellent performance is maintained for a long period of time (for example, patent document) 2).

  When the photocatalyst is irradiated with light having energy greater than the band gap as described above, electrons are excited from the valence band of the photocatalyst to the conduction band, and holes and electrons are generated. These holes and excited electrons are generated on the surface of the photocatalyst. It diffuses and reacts with harmful gases adsorbed on the surface of the photocatalyst and harmful gases diffused on the surface of the photocatalyst to make them harmless. Among photocatalysts, titanium oxide photocatalysts are most frequently used because of their strong oxidizing power and excellent chemical stability. The titanium oxide photocatalyst proceeds with the above photocatalytic reaction by absorbing light having a wavelength of about 400 nm or less.

  On the other hand, the photocatalytic reaction proceeds only on the surface of the photocatalyst or in the vicinity of the surface of the photocatalyst. For this reason, when decomposing and purifying an extremely dilute harmful gas of ppm or ppb level with a photocatalyst, the process of diffusing the harmful gas on the surface of the photocatalyst tends to be the rate-limiting step of the decomposition and purification reaction. In particular, when a harmful gas having low adsorptivity to the photocatalyst is targeted for decomposition and purification, there is a problem that the decomposition and purification rate is remarkably slowed.

Therefore, in order to solve this problem and increase the decomposition and purification rate by the photocatalytic reaction, a method of using a photocatalyst and an adsorbent in combination has been performed. For example, a purification device using a deodorizing filter in which an adsorbent powder such as activated carbon, zeolite, manganese, copper or the like is kneaded with a photocatalyst powder binder and this is coated on a honeycomb structure is disclosed (for example, see Patent Document 2). . Further, a purification device is disclosed that uses activated carbon fibers coated with titanium oxide to adsorb and purify harmful gases, and further decomposes and purifies the harmful gases adsorbed by the photocatalytic effect of titanium oxide (see, for example, Patent Document 3). ).
JP 2002-272824 A JP 2002-263175 A JP 2002-355299 A

  Many adsorbents such as activated carbon do not transmit light with a wavelength of 400 nm or less required for the photocatalytic reaction of the titanium oxide photocatalyst, or hardly transmit light. For this reason, for example, in a catalyst material in which activated carbon particles and titanium oxide particles are kneaded, increasing the content of activated carbon particles in the material reduces the amount of light reaching the photocatalyst, which is necessary for decomposition and purification of harmful substances. There is a problem that the photocatalytic reaction does not occur sufficiently. Further, when the content of the activated carbon particles is reduced, there is a problem that the amount of harmful substances adsorbed on the catalyst material is reduced, and the decomposition and purification rate is slowed down. For example, when activated carbon fiber is coated with a titanium oxide photocatalyst, the photocatalyst on the fiber surface in the direction of the light source is sufficiently irradiated with light, and the photocatalytic reaction proceeds, but the photocatalyst on the opposite side of the fiber surface The light does not reach and the photocatalytic reaction does not proceed. In order to increase the adsorption amount of harmful substances and increase the decomposition and purification rate, activated carbon fibers coated with a titanium oxide photocatalyst need to be bundled into the purification device. There is a problem that the irradiation does not reach and the photocatalytic reaction hardly proceeds.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a photocatalyst excellent in the decomposition and purification rate of harmful substances, a photocatalyst-supported ceramic porous body, a decomposition and purification method for harmful substances, and a gas purification apparatus. is there.

  Accordingly, the photocatalyst according to claim 1 for solving the above-mentioned problem is characterized in that the surface is treated with a basic or acidic solution having a pH adjusted to enhance the gas adsorption ability. .

  In the photocatalyst according to claim 1, when the photocatalyst is treated with a basic solution, the surface hydroxyl group of the photocatalyst is inclined to be basic, so that an acidic substance such as hydrogen sulfide is easily adsorbed. Further, when the photocatalyst is treated with an acidic solution, the surface hydroxyl group of the photocatalyst is inclined to be acidic, so that it is easy to adsorb a basic substance such as ammonia.

  The ceramic porous body supporting a photocatalyst according to claim 2 is a ceramic porous body supporting the photocatalyst by supporting the photocatalyst on the ceramic porous body by immersing the ceramic porous body in a sol solution of the photocatalyst and firing it. Is characterized by being immersed in a basic or acidic solution with pH adjusted.

  According to the photocatalyst-supporting ceramic porous body according to claim 2, the photocatalyst-supporting ceramic porous body has a larger surface area per unit mass than a normal photocatalyst and can adsorb a large amount of substances.

  In addition, the method for decomposing and purifying a harmful substance according to claim 3, the photocatalyst according to claim 1 or 2 or the photocatalyst-supporting ceramic porous body is irradiated with light to cause a photocatalytic reaction, and ozone is used in combination. It is characterized by decomposing harmful substances.

  According to the method for decomposing and purifying harmful substances according to claim 3, since the harmful substances can be decomposed and purified by the photocatalytic reaction and ozone, the speed of decomposition and purification can be further improved.

According to a fourth aspect of the present invention, there is provided a method for decomposing and purifying a harmful substance, wherein the harmful substance is adsorbed on a ceramic porous body that has been subjected to immersion treatment with a basic or acidic solution that has been subjected to pH adjustment to enhance gas adsorption ability. 5. The harmful substance decomposition and purification method according to claim 4, wherein the adsorbed harmful substance is decomposed by ozone. The harmful substance is adsorbed on the surface of the ceramic porous body and decomposed by ozone. Therefore, harmful substances can be quickly decomposed and purified without using a photocatalytic reaction.

  The gas purification device according to claim 5 is a gas purification device that introduces a gas to be treated into the purification device main body, passes the treatment unit, decomposes harmful substances in the gas, and then exhausts the gas. The processing unit is provided with a photocatalyst whose surface has been treated with a basic or acidic solution whose pH has been adjusted to improve the gas adsorption ability, and a light irradiation means for irradiating the photocatalyst with light. And

  According to the gas purification device of the fifth aspect, it is possible to decompose and purify harmful substances that pass through the processing section by photocatalytic reaction. In addition, the photocatalyst used is surface-treated and has an excellent ability to adsorb harmful substances, so the decomposition and purification speed is high.

  The gas purification device according to claim 6 is a gas purification device that introduces a gas to be treated into the purification device main body, passes the treatment unit, decomposes harmful substances in the gas, and then exhausts the gas. The ceramic porous body is immersed in a sol solution of a photocatalyst and baked to support the photocatalyst on the ceramic porous body, and the ceramic porous body supporting the photocatalyst is subjected to pH adjustment with a basic or acidic solution. And a light irradiating means for irradiating the photocatalyst-supported ceramic porous body with light.

  According to the gas purification device of the sixth aspect, it is possible to decompose and purify harmful substances passing through the processing section by photocatalytic reaction. Further, the photocatalyst-carrying ceramic porous body to be used is surface-treated and has an excellent ability to adsorb harmful substances, so that the decomposition and purification speed is high. The photocatalyst-carrying ceramic porous body has a larger surface area per unit mass than a normal photocatalyst and can adsorb a large amount of substances, so that the speed of decomposition and purification can be further improved.

  The gas purification device according to claim 7 is the gas purification device according to claim 5 or 6, wherein ozone is provided in the processing section.

  According to the gas purification device of the seventh aspect, in addition to the effect of the gas purification device of the fifth or sixth aspect, the decomposition and purification speed can be further improved by ozone.

  The gas purification device according to claim 8 is a gas purification device that introduces a gas to be treated into the purification device main body, passes the treatment unit, decomposes harmful substances in the gas, and then exhausts the gas. The treatment section is provided with a ceramic porous body that is immersed in a basic or acidic liquid that has been subjected to pH adjustment to enhance gas adsorption ability, and ozone generating means.

  According to the gas purification apparatus of the eighth aspect, harmful substances can be promptly decomposed and purified by ozone without using a photocatalyst.

  As the photocatalyst, titanium oxide, zinc oxide, strontium titanate, barium titanate, or the like, or a combination thereof can be used. In addition, as the ceramic porous body, titanium oxide, zinc oxide, strontium titanate, barium titanate, aluminum oxide, silicon oxide, zeolite, or the like, or a combination thereof can be used.

  In adjusting the pH, a basic solution such as an aqueous potassium hydroxide solution or an acidic solution such as an aqueous nitric acid solution can be used.

  In addition, the light irradiation referred to in the “claims” means irradiation with light capable of exciting the photocatalytic reaction.

  As is clear from the above description, the present invention has the following effects.

  By immersing the photocatalyst in a basic solution or acidic solution, the ability to adsorb harmful substances such as hydrogen sulfide and ammonia can be improved, so that harmful substances can be quickly decomposed and purified without using an adsorbent. can do. Further, when no adsorbent is used, the light irradiation efficiency is improved because the adsorbent does not block light irradiation on the photocatalyst.

  By using a photocatalyst and ozone in combination, the speed of decomposition and purification of harmful substances can be improved. In addition, by using a porous ceramic body immersed in a basic solution or acidic solution, it is possible to quickly decompose and purify harmful substances using only ozone, without using a photocatalyst. And cost reduction can be realized.

  Embodiments of the present invention will be described below. Chemisorbed water is present on the surface of the metal oxide containing the titanium oxide photocatalyst. This chemically adsorbed water is adsorbed on the surface of the metal oxide in a dissociated state, and forms a hydroxyl group on the surface of the metal oxide like M-OH (M represents a metal). Due to this surface hydroxyl group, the surface of the metal oxide exhibits both properties of a solid acid and a solid base. The property of the solid acid is attributed to a reaction in which the surface hydroxyl group releases a proton as shown in the following chemical formula 1, and the property of the solid base is attributed to a reaction in which the surface hydroxyl group receives a proton as in the chemical formula 2 below.

  The hydroxyl group on the surface of the metal oxide varies in degree of dissociation depending on the electronegativity and coordination number of the metal, and the properties of the solid acid and solid base of the surface hydroxyl group also vary depending on the electronegativity and coordination number of the metal. . In ordinary titanium oxide photocatalysts, there are mainly two types of surface hydroxyl groups, and the dissociation constants are reported as pKa = 12.7 and pKa = 2.9, respectively (Satoru Kiyono, “Titanium oxide”, (Refer to Gihodo.) However, it is considered that surface hydroxyl groups having various properties exist in addition to the surface hydroxyl groups due to differences in surface structure.

  In the present invention, this surface hydroxyl group is treated with an acidic solution or a basic solution, thereby facilitating adsorption of harmful substances to the surface hydroxyl group and realizing an improvement in purification treatment speed.

  Specifically, when the titanium oxide photocatalyst is immersed in a basic solution, the surface hydroxyl group of titanium oxide releases protons as shown in the following chemical formula 3, and a basic titanium oxide surface can be obtained. This basic surface has the property of easily adsorbing acidic gas such as hydrogen sulfide, and the purification rate of acidic gas can be improved by surface-treating the titanium oxide photocatalyst with a basic solution. Further, when the titanium oxide photocatalyst is immersed in an acidic solution, the surface hydroxyl group of titanium oxide receives protons as shown in the following chemical formula 4, and an acidic titanium oxide surface can be obtained. This acidic surface has the property of easily adsorbing a basic gas such as ammonia, and the purification rate of the basic gas can be improved by surface-treating the titanium oxide photocatalyst with an acidic solution.

  In this embodiment, since an adsorbent that prevents light from reaching the photocatalyst is not used, the photocatalyst can be irradiated with sufficient light to induce a photocatalytic reaction. Can be adsorbed on the surface of the photocatalyst, so that the purification rate of harmful substances can be improved.

  In addition to titanium oxide, zinc oxide, strontium titanate, barium titanate, or the like can be used for the photocatalyst of the present invention.

(Preparation of sample 1)
The preparation of Sample 1 will be described with reference to FIG. First, in the immersion step 1, a ceramic porous body made of cordierite and having a pore diameter of 2 to 3 mm was immersed in a sol solution of titanium oxide.

  After the ceramic porous body was pulled up from the sol solution, in the removal step 2, the sol solution remaining inside the pores was removed with a blower.

  The ceramic porous body from which the sol solution inside the pores was removed was fired at 500 ° C. in the firing step 3 to obtain a titanium oxide-supported ceramic porous body (hereinafter referred to as a titanium oxide porous body).

  This titanium oxide porous body was immersed in basic water whose pH was adjusted to 9.6 in the second immersion step 4 for 1 hour. The basic water was adjusted to a predetermined pH by adding an aqueous potassium hydroxide solution to distilled water.

  The titanium oxide porous body after immersion was dried at 110 ° C. for about 2 hours in the drying step 5 to complete the base-treated titanium oxide porous body 1 as the sample 1.

(Preparation of sample 2)
In the preparation of the sample 1, the pH of the basic water in the second immersion step 4 is adjusted to 8.4, and the other steps are the same as the preparation of the sample 1 and the sample is the base-treated titanium oxide porous material. Completed Body 2.

(Preparation of sample 3)
In the preparation of the sample 1, the pH of the basic water in the second immersion step 4 is adjusted to 7.4, and the other steps are the same as the preparation of the sample 1 and the sample is the base-treated titanium oxide porous material. Completed body 3.

(Preparation of sample 4)
In the preparation of the sample 1, in place of the basic water used in the second immersing step 4, acid water whose pH was adjusted to 5.7 by adding a nitric acid aqueous solution to distilled water was used. The acid-treated titanium oxide porous body 1 as the sample 4 was completed by performing the same operation as in the preparation.

(Preparation of sample 5)
In the preparation of the sample 1, in place of the basic water used in the second immersion step 4, tap water (pH = 6.7) is used, and the other steps are performed in the same manner as in the preparation of the sample 1, and the sample 5 is used. An acid-treated titanium oxide porous body 2 was completed.

(Preparation of sample 6)
In the preparation of the sample 1, the second immersion step 4 was not performed, and in the other steps, the same operation as the preparation of the sample 1 was performed to complete the titanium oxide porous body as the sample 6.

(Example 1)
Each of the samples 1 to 6 was prepared to have a size of 40 mm in length, 40 mm in width, and 25 mm in height, placed in a 1 L volume Pyrex (registered trademark) glass container, and the glass container was sealed. Hydrogen sulfide was introduced into the container so that the concentration of hydrogen sulfide was 2 ppm while maintaining the hermeticity. After introducing hydrogen sulfide, let stand for 1 hour in dark condition with light blocked, and when the conditions sufficient for hydrogen sulfide adsorption on the porous titanium oxide to reach equilibrium are met, the concentration of hydrogen sulfide in the container is measured And measured. Further, in order to compare with the test results, a similar test (blank test) was performed on a glass container not containing a titanium oxide porous body, and the hydrogen sulfide concentration was measured.

  The measurement result of the hydrogen sulfide concentration is shown in FIG. Hydrogen sulfide was not detected from the glass containers using Samples 1-5. Moreover, from the glass container using the sample 6, the hydrogen sulfide of the density | concentration lower than a blank test was detected.

  As shown in Chemical Formula 3, the titanium oxide porous material treated with basic water has a basic surface, and acidic hydrogen sulfide is easily adsorbed on the surface of the basic titanium oxide porous material. The porous titanium oxides of Samples 1 to 3 are considered to be excellent in hydrogen sulfide adsorption ability. Moreover, since the weak acidic point of the porous body surface reacted and the porous body processed with acidic water converted into the basic point, it is thought that the samples 4 and 5 are excellent in the adsorption ability of hydrogen sulfide.

  From the above results, it was shown that the titanium oxide porous body that was surface-treated with basic water or acidic water was excellent in hydrogen sulfide adsorption ability.

(Example 2)
Each of the samples 1 to 6 was prepared in a size of 227 mm in length, 227 mm in width, and 20 mm in height, and installed in the deodorizing apparatus shown in FIG. In FIG. 3, the deodorizing device introduces gas from the suction port 32 by the rotation of the fan 31, passes the titanium oxide porous body 33 made of each of the samples 1 to 6, and then exhausts the gas from the exhaust port 34. In addition, by irradiating the titanium oxide porous body 33 with the black light 35, the passing gas can be purified by a photocatalytic reaction.

This deodorizing apparatus was installed in an acrylic test chamber having a volume of 1 m ³ and the acrylic test chamber was sealed. With the deodorizer switch turned off, hydrogen sulfide was introduced into the test chamber so that the hydrogen sulfide concentration was 120 ppb. After introducing hydrogen sulfide, it was allowed to stand for 2 minutes, the deodorizing device was turned on, and the purification treatment by the photocatalytic reaction of the titanium oxide porous body 33 was started. The concentration of hydrogen sulfide during the treatment was continuously measured, and the hydrogen sulfide purification rate (pseudo first-order reaction rate constant) was obtained for each sample 1-6. The results are shown in Table 1.

  As shown in Table 1, the sample 1 has the highest purification rate, and the titanium oxide porous material (samples 1 to 5) subjected to surface treatment with basic water or acidic water is not treated with untreated titanium oxide. The purification rate was remarkably improved as compared with the body (sample 6), and the effectiveness of the surface treatment for improving the purification rate was shown.

Example 3
From the results of Examples 1 and 2, it was revealed that the adsorption ability of hydrogen sulfide on the surface of the porous titanium oxide body is improved by the immersion treatment with basic water or acidic water. On the other hand, when hydrogen sulfide molecules are adsorbed on the surface of the titanium oxide porous body, the next hydrogen sulfide molecules cannot be adsorbed on the surface until the decomposition reaction of hydrogen sulfide by the photocatalyst is completed. Therefore, in order to quickly decompose the adsorbed hydrogen sulfide molecules, a combined test of ozone gas and photocatalysis was performed.

  In the test of Example 2, an ozone generator was installed in the test chamber, the deodorizer was switched on and at the same time the ozone was generated from the ozone generator, and the change in hydrogen sulfide concentration was measured. .

The test results are shown in FIG. When photocatalyst and ozone are used together (O ₃ / TiO ₂ / BL), the rate of decrease in hydrogen sulfide concentration is greater than when ozone is not used together (TiO ₂ / BL), and photocatalyst and ozone are used in combination. It was shown that the purification rate of hydrogen sulfide was improved. In addition, there was no difference between the case where the titanium oxide porous body not subjected to the immersion treatment and ozone were used in combination (not shown) and the case of only the titanium oxide porous body not subjected to the immersion treatment (not shown). . Therefore, it was shown that only the titanium oxide porous body that has been subjected to immersion treatment to improve the adsorption ability has the effect of combined use with ozone.

Example 4
In Example 3, ozone was generated simultaneously with turning on the switch of the deodorizing device. On the other hand, in Example 4, ozone was generated in the laboratory in advance, and the ozone was adsorbed to the titanium oxide porous body. In this state, the deodorizer was turned on to start purification of hydrogen sulfide. did. Note that no ozone was generated after the deodorizer was turned on. The results are shown in FIG. 4 (pre-O ₃ / TiO ₂ / BL). It was shown that the purification rate of hydrogen sulfide can be improved by previously generating ozone in the laboratory as in this example.

(Example 5)
In Example 5, hydrogen sulfide is introduced into the laboratory so that the concentration becomes 70 ppb, and ozone is generated simultaneously with turning on the switch of the deodorizer, and the black light in the deodorizer of FIG. The experiment was conducted without light irradiation by 35. Moreover, as a comparative experiment, an experiment in which light was irradiated by the black light 35 and an experiment in which purification was performed using only ozone without using a deodorizing apparatus were performed.

The results are shown in FIG. When light irradiation by the black light 35 is not performed (O ₃ / TiO ₂ / Dark), the purification rate is further improved compared to when light irradiation by the black light 35 is performed (O ₃ / TiO ₂ / BL). It has been shown. Further, a higher purification rate is obtained than in the case of the experiment using only ozone (O ₃ ).

  From these results, it is possible to improve the adsorption rate of hydrogen sulfide and ozone on the surface of the titanium oxide porous body by immersing the titanium oxide porous body, and the hydrogen sulfide and ozone react efficiently on the surface of the titanium oxide porous body. Is thought to improve. In addition, these results indicate that hydrogen sulfide can be quickly purified without using a purification reaction by a photocatalytic reaction in the immersion-treated titanium oxide porous body.

  In addition to the titanium oxide, a metal oxide having a surface hydroxyl group such as zinc oxide, strontium titanate, barium titanate, aluminum oxide, silicon oxide, or zeolite can be used in this embodiment.

Process drawing of sample preparation. The figure which shows the measurement result of the hydrogen sulfide density | concentration in Example 1. FIG. The block diagram of a deodorizing apparatus. The figure which shows the measurement result of the hydrogen sulfide density | concentration in Example 3 and 4. FIG. The figure which shows the measurement result of the hydrogen sulfide density | concentration in Example 5. FIG. The top view of the air cleaner by combined use of ozone and a photocatalyst. The longitudinal cross-sectional view of the air purification apparatus which used together the adsorption agent and photocatalyst containing at least 1 sort (s) of activated carbon and a zeolite.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Immersion process 2 ... Removal process 3 ... Baking process 4 ... 2nd immersion process 5 ... Drying process 31 ... Fan 32 ... Suction port 33 ... Titanium oxide porous body 34 ... Exhaust port 35 ... Black light

Claims (8)

A photocatalyst characterized in that the surface is treated with a basic or acidic solution having a pH adjusted to enhance the gas adsorption ability. The ceramic porous body is immersed in a sol solution of a photocatalyst and baked to support the photocatalyst on the ceramic porous body, and the ceramic porous body supporting the photocatalyst is subjected to pH adjustment with a basic or acidic solution. A photocatalyst-supported ceramic porous body that is immersed in The photocatalyst according to claim 1 or 2, wherein the photocatalyst-supporting ceramic porous body is irradiated with light to cause a photocatalytic reaction, and ozone is used in combination to decompose the harmful substance. Method. It is characterized by adsorbing harmful substances to a porous ceramic body with enhanced gas adsorption capacity by dipping in a basic or acidic solution with pH adjustment, and decomposing the adsorbed harmful substances with ozone. Decomposition and purification method for harmful substances. In the gas purification apparatus that introduces the gas to be treated into the purification apparatus body, passes the treatment section, decomposes harmful substances in the gas, and then exhausts the gas,
The processing unit is provided with a photocatalyst whose surface has been treated with a basic or acidic solution whose pH has been adjusted to improve the gas adsorption ability, and a light irradiation means for irradiating the photocatalyst with light. Gas purification device. In the gas purification apparatus that introduces the gas to be treated into the purification apparatus body, passes the treatment section, decomposes harmful substances in the gas, and then exhausts the gas,
The ceramic porous body is immersed in a sol solution of a photocatalyst and baked to support the photocatalyst on the ceramic porous body, and the ceramic porous body supporting the photocatalyst is subjected to pH adjustment with a basic or acidic solution. A gas purification apparatus comprising: a catalyst-carrying ceramic porous body that has been soaked in step 1; and a light irradiation means that irradiates the photocatalyst-supported ceramic porous body with light. In the gas purification apparatus according to claim 5 or 6,
A gas purification apparatus characterized in that an ozone generating means is provided in the processing section. In the gas purification apparatus that introduces the gas to be treated into the purification apparatus body, passes the treatment section, decomposes harmful substances in the gas, and then exhausts the gas,
A gas purification apparatus comprising a ceramic porous body that has been immersed in a basic or acidic liquid that has been subjected to pH adjustment in the treatment section to enhance gas adsorption ability, and ozone generation means.

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