JP2011000544A - Method for regenerating photocatalyst and apparatus for cleaning corrosive gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating a photocatalyst that determines the deterioration degree of a photocatalyst member with changes in color of the photocatalyst member and regenerates changes in color and catalytic activity accompanied with the deterioration of a photocatalyst in accordance with determination results and an apparatus for cleaning a corrosive gas having the photocatalyst member to be regenerated with this regeneration method.SOLUTION: The apparatus 1 for cleaning a corrosive gas decomposes and removes the corrosive gas by allowing the corrosive gas to contact the photocatalyst filter 2 of a complex compound where at least one metal out of platinum, silver, copper, and vanadium is supported on titanium oxide. The color of the photocatalyst filter 2 is detected by a color detecting means 3 (color sensor) and a deterioration degree determining means 4 determines the deterioration degree of the photocatalyst based on the changes in color of the photocatalyst filter 2. Based on the determination by the deterioration degree determining means 4, a photocatalyst regenerating means 5 allows a cleaning liquid containing an oxidizing agent to contact the photocatalyst filter 2, thereby regenerating the photocatalyst filter 2.

Description

  The present invention provides a photocatalyst regeneration method for cleaning a photocatalyst member in which a photocatalyst of a composite compound in which noble metal (made of at least one of platinum, silver, copper, and vanadium) is supported on titanium oxide is coated on the member, and the photocatalyst member The present invention relates to a corrosive gas purification device provided with Specifically, the deterioration of the photocatalyst associated with the purification of the corrosive gas is determined based on a change in the color of the photocatalyst member, the photocatalyst member is washed according to the determination result, and the catalyst performance is recovered. The present invention relates to a regenerating photocatalyst and a corrosive gas purification device.

  Titanium oxide photocatalysts are known to have a purifying action for decomposing harmful substances in the air and water, an antibacterial action, and an antifouling action.

  When the titanium oxide photocatalyst is irradiated with light having energy higher than the band gap, electrons are excited from the valence band to the conductor, and electron-hole pairs are generated. The excited electrons diffuse to the surface of the photocatalyst and react with the surface adsorbed water to generate active oxygen species such as OH radicals. The active oxygen species, holes and the like decompose the harmful substances adsorbed or collided with the photocatalyst surface.

  The band gap of titanium oxide is about 3.0 eV, and an excitation reaction occurs by irradiating light with a wavelength of about 400 nm or less, and harmful substances can be removed.

  When a photocatalyst member coated with titanium oxide photocatalyst (filter, etc.) is used to remove corrosive gas as a purification device for corrosive gas (nitrogen oxide gas, hydrogen sulfide gas, etc.) present in the environment The decomposition products when the corrosive gas is decomposed accumulate on the surface of the photocatalytic member. When the corrosive gas to be purified has a high concentration or when the photocatalyst is used for a long period of time, the surface of the photocatalyst member is covered with decomposition products and the like, and the catalytic performance of the photocatalyst is degraded. In this state, the surface of the photocatalyst member changes significantly.

  That is, the surface of the photocatalyst member is discolored and looks bad, and the decomposition ability with respect to corrosive gas is reduced.

  Therefore, in order to recover the catalytic ability of the photocatalyst, the photocatalyst member is periodically cleaned. Then, the catalyst capacity is confirmed during the regular cleaning, and when a decrease in the catalyst capacity is confirmed, a catalyst capacity recovery operation is performed.

  For example, in the method for regenerating a photocatalyst described in Patent Document 1, the photocatalyst sheet is periodically washed, the oxidation product of air pollutants adsorbed on the surface is eluted to recover the photocatalytic activity, and then the catalyst is further recovered. The capacity is confirmed, and an alkali agent is added to the photocatalyst sheet as necessary to enhance the decontamination function of the photocatalyst during reuse.

  In recent years, high-output blue LEDs (Light Emitting Diodes) and pure green LEDs have become available, and full-color sensors using three primary color LEDs as light emitting elements have been developed (for example, Non-Patent Documents 1 and 2). ).

  A color sensor is a sensor that separates reflected light from a detection body into components of R (red), G (green), and B (blue), which are the three primary colors of light, and determines the color based on the ratio.

  A full-color sensor using three primary color LEDs has an advantage that a subtle color difference can be detected as compared with the case of using monochromatic light. Subtle color differences can be detected by a full-color sensor using an incandescent lamp, but a full-color sensor using three primary color LEDs has the advantages of long life, low power consumption, and low heat generation.

JP-A-10-305214

Mitsutoshi Nomura, Katsuya Shibata “Development of SA1J-F Fiber Type Full Color Sensor Using Three Primary Color LEDs”, [online], December 1, 1999, IDEC REVIEW, [Search April 27, 2009], Internet <URL: http: // www. idec. com / jpja / technology_solution / tech_resources / pdfs2 / IRV_1999_13. pdf> “Digital Color Discriminating Sensor CZ”, [online], [Search on April 27, 2009], Internet <URL: http: // www. keyence. co. jp / switch / color / cz / menu / 236 />

  In the above prior art, the substance derived from the corrosive gas attached to the surface of the photocatalyst member can be removed by simple water washing. However, when the corrosive gas has a high concentration or when the photocatalyst member is used for a long period of time, the degree of discoloration is large, and the photocatalytic performance may not be recovered by simple water washing. Further, even when the catalyst performance is recovered by washing with water, the discoloration of the surface of the photocatalyst member may not be completely recovered.

  Therefore, the present invention provides a photocatalyst regeneration method capable of recovering the catalytic activity of the photocatalyst and recovering the discoloration of the surface of the photocatalyst member, and a corrosive gas purification device provided with the photocatalyst member regenerated by the photocatalyst regeneration method. The purpose is that.

  The photocatalyst regeneration method of the present invention that achieves the above object is the photocatalyst of a composite compound in which at least one metal of platinum, silver, copper, and vanadium is supported on titanium oxide, based on the change in color of the photocatalyst. It is characterized in that the photocatalyst is regenerated by contacting the photocatalyst with a cleaning solution containing an oxidant based on the determination.

  Further, the corrosive gas purifying apparatus of the present invention that achieves the above object is provided by contacting corrosive gas with a photocatalyst of a composite compound in which at least one metal of platinum, silver, and copper vanadium is supported on titanium oxide. A corrosive gas purification device that decomposes and removes a toxic gas, a color detection means for detecting the color of the photocatalyst, and a degree of deterioration of the photocatalyst based on a change in the color of the photocatalyst detected by the detection means And a photocatalyst regeneration unit that regenerates the photocatalyst by bringing the photocatalyst into contact with a cleaning liquid containing an oxidant based on the determination of the degradation degree determination unit.

  According to the above invention, the catalytic activity of the photocatalyst can be maintained above a certain level.

1 is a schematic view of a corrosive gas purification device according to an embodiment of the present invention. The figure which shows the catalytic activity of the photocatalyst filter after wash | cleaning which concerns on Example 1 of this invention. The figure which shows the catalytic activity of the photocatalyst filter after wash | cleaning which concerns on Example 5 of this invention. The figure which shows the catalytic activity of the photocatalyst filter after repeating washing | cleaning which concerns on Example 1 of this invention. The figure which shows the catalytic activity of the photocatalyst filter after repeating washing | cleaning which concerns on Example 5 of this invention.

  The present invention relates to a case where a photocatalyst member coated with a photocatalyst of a composite compound in which noble metal (made of at least one of platinum, silver, copper and vanadium) is supported on titanium oxide is used for decomposition of corrosive gas. This solves the problem that the decomposition ability of the corrosive gas is reduced with the decomposition of the corrosive gas, and the photocatalyst member is discolored due to the supported metal.

  When cleaning the photocatalyst member to recover the catalytic activity of the photocatalyst, by recovering the discoloration of the surface of the photocatalyst member, it becomes possible to determine the degree of degradation of the catalyst ability by the discoloration of the photocatalyst member, and efficiently the photocatalyst The member can be cleaned.

  That is, although the photocatalyst member cleaning time differs depending on the concentration and decomposition time of the corrosive gas, according to the photocatalyst regeneration method of the present invention and the corrosive gas cleaning device provided with the photocatalyst member regenerated by the photocatalyst regeneration method of the present invention, Since the photocatalyst member discoloration determination can be made based on whether or not the degree of discoloration set in advance has been reached, maintenance of the photocatalyst member can be performed with an appropriate cleaning cycle. Therefore, the corrosive gas purification device has an effect that the decomposition ability of the photocatalytic member can be maintained at a certain level or higher.

  Hereinafter, the present invention will be described in detail with specific examples.

  In the embodiment of the present invention, as a photocatalyst member, a photocatalyst filter in which the surface of a ceramic filter is coated with a titanium oxide photocatalyst is shown as an example. It can also be applied to a photocatalyst member coated with a photocatalyst on the surface, or a photocatalyst member fixed to a cloth or the like. Further, the photocatalyst itself may be used as the photocatalyst member.

Example 1
A corrosive gas purification apparatus according to an embodiment of the present invention will be described in detail with reference to FIG.

  A corrosive gas purification apparatus 1 according to an embodiment of the present invention includes a photocatalytic filter 2, a color detection unit 3 (hereinafter referred to as a color sensor), a deterioration degree determination unit 4, a photocatalyst cleaning unit 5, and a control unit 6.

  The photocatalytic filter 2 is obtained by coating a ceramic support of a foam structure with a titanium oxide photocatalyst, and has a three-dimensional structure in which voids are randomly arranged. In this example, a 90 × 70 × 40 mm photocatalytic filter 2 was used. When the corrosive gas is purified by the photocatalytic filter 2, substances derived from the corrosive gas accumulate on the surface of the photocatalytic filter 2. The color of the photocatalytic filter 2 is an unused product and is almost white. As the substance derived from the corrosive gas accumulates, the color changes to blackish green.

  A known color sensor 3 may be used (for example, Non-Patent Documents 1 and 2). In particular, the color sensor 3 using three primary color LEDs is preferable because it has a long life and generates little heat.

  The color sensor 3 can detect a change in the color of the photocatalytic filter 2. Then, based on the detected color, the deterioration degree determination means 4 determines the deterioration degree of the photocatalytic filter 2.

  The deterioration degree determination means 4 determines the deterioration degree of the photocatalytic filter 2 based on the color detected by the color sensor 3. As a method for determining the degree of deterioration, there is a method for evaluating the degree of deterioration by determining whether or not the color detected by the color sensor 3 has reached a preset degree of discoloration.

  The photocatalyst cleaning means 5 cleans the photocatalyst filter 2 when it is determined that the catalyst filter 2 needs to be cleaned based on the deterioration degree determined by the deterioration degree determination means 4. As a method for cleaning the photocatalytic filter 2, as shown in FIG. 1, an apparatus for spraying a cleaning liquid containing an oxidizing agent onto the photocatalytic filter 2 can be used. In addition, the apparatus which immerses the photocatalyst filter 2 in the washing | cleaning liquid containing an oxidizing agent may be sufficient.

  The control unit 6 determines whether or not the photocatalyst filter 2 needs to be cleaned based on the deterioration degree determined by the deterioration degree determination unit 4 and controls the photocatalyst cleaning unit 5. Note that the deterioration degree determined by the deterioration degree determination means 4 may be displayed by a deterioration degree display means (alarm lamp or the like) (not shown), and the photocatalytic filter 2 may be washed based on this display.

  In the Example of this invention, the photocatalyst filter was reproduced | regenerated by the method of immersing the photocatalyst filter 2 in the washing | cleaning liquid containing an oxidizing agent.

  As a cleaning liquid for cleaning the photocatalytic filter 2, 1L of pure water is put into a beaker, and 10mL of about 5% sodium hypochlorite solution (chlorine kitchen hitter manufactured by Kao Corporation) is added, and hypochlorous acid having a concentration of 500ppm. An aqueous sodium solution was prepared and used.

  The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 30 minutes. Thereafter, the photocatalytic filter 2 was pulled up from the solution, drained, and then rinsed with running tap water. The washed photocatalytic filter 2 was dried in a dryer at 120 ° C. for 3 hours.

(Example 2)
The corrosive gas purification apparatus according to Embodiment 2 of the present invention is the same as the corrosive gas purification apparatus 1 according to Embodiment 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  A sodium hypochlorite aqueous solution having a concentration of 500 ppm was obtained in the same manner as in Example 1. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 15 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

(Example 3)
The corrosive gas purification apparatus according to Embodiment 3 of the present invention is the same as the corrosive gas purification apparatus 1 according to Embodiment 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  1 L of tap water was put into a beaker, and 10 mL of an about 5% sodium hypochlorite solution (chlorine kitchen hitter manufactured by Kao Corporation) was added to obtain an aqueous sodium hypochlorite solution having a concentration of 500 ppm. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 30 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

Example 4
The corrosive gas purification apparatus according to Example 4 of the present invention is the same as the corrosive gas purification apparatus 1 according to Example 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  A sodium hypochlorite aqueous solution having a concentration of 500 ppm was obtained in the same manner as in Example 3. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 15 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

  About the photocatalyst filter 2 cleaned by the cleaning method of Examples 1 to 4, the color was visually observed, and compared with the unused photocatalyst filter 2, the corrosive gas (nitrogen oxide gas or It was determined how much the substance derived from hydrogen sulfide gas) was removed and the photocatalytic filter 2 was decolorized. The results are shown in Table 1.

  In all of Examples 1 to 4 which are washing conditions using sodium hypochlorite, an excellent decoloring effect was confirmed, and the color of the photocatalytic filter 2 was restored to a level equivalent to that of an unused product. From this, corrosive gas-derived substances accumulated on the surface of the photocatalytic filter 2 are immersed in an aqueous solution in which sodium hypochlorite is dissolved in pure water and tap water to a level equivalent to that of an unused product. It turns out that it is decolored.

(Example 5)
The corrosive gas purification apparatus according to Embodiment 5 of the present invention is the same as the corrosive gas purification apparatus 1 according to Embodiment 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  1 L of pure water of about 40 ° C. was put into a beaker, and 10 g of a detergent containing sodium percarbonate (oxygen kitchen hitter manufactured by Kao Corporation) was added to obtain an aqueous solution containing sodium percarbonate. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 15 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

(Example 6)
The corrosive gas purification apparatus according to Embodiment 6 of the present invention is the same as the corrosive gas purification apparatus 1 according to Embodiment 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  1 L of tap water of about 40 ° C. was put into a beaker, and 10 g of a detergent containing sodium percarbonate (oxygen kitchen hitter manufactured by Kao Corporation) was added to obtain an aqueous solution containing sodium percarbonate.

  The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 15 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

(Example 7)
The corrosive gas purification apparatus according to Example 7 of the present invention is the same as the corrosive gas purification apparatus 1 according to Example 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  In the same manner as in Example 6, an aqueous solution containing sodium percarbonate was obtained. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 30 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

(Example 8)
The corrosive gas purification apparatus according to Example 8 of the present invention is the same as the corrosive gas purification apparatus 1 according to Example 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  1 L of pure water at about 40 ° C. was placed in a beaker, and 4 g of a detergent containing sodium percarbonate (oxygen kitchen hitter manufactured by Kao Corporation) was added to obtain an aqueous solution containing sodium percarbonate.

  The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 15 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

Example 9
The corrosive gas purification apparatus according to Embodiment 9 of the present invention is the same as the corrosive gas purification apparatus 1 according to Embodiment 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  1 L of tap water at about 40 ° C. was put into a beaker, and 4 g of detergent containing sodium percarbonate (oxygen kitchen hitter manufactured by Kao Corporation) was added to obtain an aqueous solution containing sodium percarbonate. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 15 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

(Example 10)
The corrosive gas purification apparatus according to Example 10 of the present invention is the same as the corrosive gas purification apparatus 1 according to Example 1 of the present invention. Therefore, the same means as those constituting the corrosive gas purification device 1 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  If it is determined that the photocatalytic filter 2 needs to be cleaned based on the deterioration level determined by the deterioration level determination means 4, the photocatalytic filter 2 is cleaned.

  In the same manner as in Example 9, an aqueous solution containing sodium percarbonate was obtained. The photocatalytic filter 2 in which the substance derived from the corrosive gas was accumulated in this solution was immersed for 30 minutes. Thereafter, the photocatalytic filter 2 was rinsed and dried in the same manner as in Example 1.

  About the photocatalyst filter 2 cleaned by the cleaning methods of Examples 5 to 10, the color was visually observed, and compared with the unused photocatalyst filter 2, corrosive gas accumulated on the surface of the photocatalyst filter 2 (nitrogen oxide gas or It was determined how much the substance derived from hydrogen sulfide gas) was removed and the photocatalytic filter 2 was decolorized. The results are shown in Table 2.

  In all of Examples 5 to 10 which are washing conditions using sodium percarbonate, an excellent decoloring effect was confirmed, and the color of the photocatalytic filter 2 was restored to a level equivalent to that of an unused product. From this, the corrosive gas-derived substance accumulated on the surface of the photocatalytic filter 2 is immersed in an aqueous solution in which 4 g of sodium percarbonate is dissolved in 1 L of pure water or tap water to a level equivalent to that of an unused product. It turns out that it is decolored.

  As described above, it is possible to remove the corrosive gas-derived substances accumulated on the surface of the photocatalytic filter 2 and recover the discoloration of the photocatalytic filter 2 under any of the cleaning conditions of Examples 1 to 4 and Examples 5 to 10.

  When sodium hypochlorite is used, depending on the pH of the water used, harmful and corrosive chlorine gas may be generated, so it is more preferable to use sodium percarbonate.

  Next, a gas purification test is performed using the photocatalyst filter 2 washed by the washing method shown in Example 1 and Example 5, and the gas purification of the photocatalyst filter 2 by the washing method shown in Example 1 and Example 5 is performed. We evaluated how much the performance recovered.

In the gas purification test, hydrogen sulfide gas was used as a corrosive gas. The test was conducted in an acrylic test chamber having an effective volume of 1 m ³ .
The corrosive gas purification device 1 is set in the test chamber, and hydrogen sulfide gas is injected from the external pipe. The hydrogen sulfide gas concentration in the test chamber was about 500 ppb. In order to make the internal gas concentration uniform, the operation of the corrosive gas purification apparatus 1 was started in a state where the air in the test chamber was stirred using a small fan.

  The change over time in the hydrogen sulfide gas concentration in the test chamber was measured with a hydrogen sulfide continuous measuring device immediately before the start of operation. From this continuous measurement result, the recovery performance of the photocatalytic filter 2 with the sodium hypochlorite cleaning solution and the sodium percarbonate cleaning solution was evaluated.

  As a comparison, the purification performance of the unused photocatalyst filter 2 and the filter 2 before cleaning in which substances derived from corrosive gas accumulated were also tested by the same test method.

  FIG. 2 shows the results of washing with a sodium hypochlorite washing solution (washing method of Example 1), and FIG. 3 shows the results of washing with a sodium percarbonate washing solution (washing method of Example 5).

  As shown in FIG. 2, in the unused photocatalytic filter 2 (initial value: Δ), approximately 500 ppb of hydrogen sulfide gas can be reduced to 10 ppb or less in 22 minutes. On the other hand, in the photocatalytic filter 2 in which the substance derived from the corrosive gas is accumulated (accumulation of the substance derived from the corrosive gas: ◯), it takes 37 minutes for the hydrogen sulfide gas of about 500 ppb to become 10 ppb or less. From this, it is understood that the purification performance of the photocatalytic filter 2 against the corrosive gas is deteriorated by the accumulation of the substance derived from the corrosive gas on the surface of the photocatalytic filter 2.

  In the photocatalytic filter 2 after the photocatalytic filter 2 in which the substance derived from the corrosive gas is accumulated is washed with an aqueous sodium hypochlorite solution, the hydrogen sulfide gas of about 500 ppb becomes 10 ppb or less after 17 minutes. From this, accumulation of substances derived from corrosive gas on the surface of the photocatalytic filter 2 reduces the purification function of the photocatalytic filter 2 with respect to the corrosive gas, but the corrosive gas is washed by washing with a sodium hypochlorite cleaning solution. The derived material can be removed, and the purification performance of the photocatalytic filter 2 can be recovered to the purification performance level of the unused photocatalytic filter 2.

  Similarly, as shown in FIG. 3, the sodium percarbonate cleaning solution can provide the same effect as the sodium hypochlorite cleaning solution.

(Example 11)
The cleaning process of Example 1 was repeated 30 times, and the cleaning durability of the photocatalytic filter 2 with respect to the cleaning liquid containing sodium hypochlorite was evaluated. The result is shown in FIG.

(Example 12)
The cleaning process of Example 5 was repeated 30 times, and the cleaning durability of the photocatalytic filter 2 with respect to the cleaning liquid containing sodium percarbonate was evaluated. The result is shown in FIG.

  4 and 5, no deterioration in the performance of the photocatalytic filter 2 was confirmed using a cleaning solution containing sodium hypochlorite or a cleaning solution containing sodium percarbonate.

  As described above, according to the photocatalyst regeneration method and the corrosive gas purification device according to the present invention, the substance derived from the corrosive gas (nitrogen oxide gas, hydrogen sulfide gas, etc.) attached to the photocatalyst member (photocatalyst filter). Can be easily removed, and the discoloration of the photocatalyst member can also be reproduced. Since the discoloration of the photocatalyst member can be regenerated, the degree of deterioration of the photocatalyst member can be evaluated based on the change in the color of the photocatalyst.

  Although the change in the color of the photocatalyst member can be confirmed visually, the change in the color of the photocatalyst member can be detected by measuring the color sensor 3 so that a subtle change in color can be detected. The photocatalyst member can be cleaned with a proper cleaning cycle.

  The cleaning liquid used for cleaning the photocatalyst member is a commercially available cleaning liquid prepared from household bleach and cleaning agents. It is easily available, has excellent operability, and can effectively clean the photocatalyst member. It is. In addition, as the cleaning liquid, an oxidizing cleaning liquid may be used as appropriate.

  The photocatalyst regeneration method according to the present invention is not limited to the examples, and the type of the color sensor, the composition of the cleaning liquid, and the like can be appropriately selected as long as the object is achieved.

In addition, some of the substances derived from the corrosive gas accumulated on the surface of the photocatalyst (photocatalyst member) exhibit acidity when dissolved in water (for example, SO ₄ ²⁻ , NO ₃ ⁻ ). If the photocatalyst member is preliminarily washed with water or the like before being immersed in the photocatalyst member and then immersed in the cleaning liquid, the cleaning liquid can be prevented from being deteriorated.

DESCRIPTION OF SYMBOLS 1 ... Corrosive gas purification apparatus 2 ... Photocatalyst filter (photocatalyst member)
3. Color sensor (color detection means)
4 ... Degradation degree determination means 5 ... Photocatalyst regeneration means

Claims (7)

In a photocatalyst of a composite compound in which at least one metal of platinum, silver, copper, and vanadium is supported on titanium oxide,
Based on the change in color of the photocatalyst, determine the degree of degradation of the photocatalyst,
Based on this determination, the photocatalyst is regenerated by bringing the photocatalyst into contact with a cleaning liquid containing an oxidizing agent to regenerate the photocatalyst. The photocatalyst regeneration method according to claim 1, wherein the color change is measured by a color sensor. The photocatalyst regeneration method according to claim 1 or 2, wherein the photocatalyst is regenerated with the cleaning liquid after being washed with water. The photocatalyst regeneration method according to any one of claims 1 to 3, wherein the oxidizing agent is either sodium hypochlorite or sodium percarbonate. The photocatalyst regeneration method according to any one of claims 1 to 4, wherein the photocatalyst purifies nitrogen oxides or hydrogen sulfide. A corrosive gas purification device that decomposes and removes corrosive gas by bringing the corrosive gas into contact with a photocatalyst of a composite compound in which at least one metal of platinum, silver, copper, and vanadium is supported on titanium oxide,
Color detection means for detecting the color of the photocatalyst;
A deterioration degree determination means for determining a deterioration degree of the photocatalyst based on a change in the color of the photocatalyst detected by the detection means;
A corrosive gas purification device comprising: a photocatalyst regeneration unit that regenerates the photocatalyst by bringing a cleaning liquid containing an oxidant into contact with the photocatalyst based on the determination by the deterioration degree determination unit. The corrosive gas purification apparatus according to claim 6, further comprising a deterioration degree display means for displaying a deterioration degree of the photocatalyst.

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