JP2009291398A - Method for operating air quality purifier - Google Patents

Abstract

[PROBLEMS] To secure a sufficient amount of light for a catalytic reaction to a photocatalytic member containing fluorine-containing titanium oxide and to suppress a decrease in fluorine concentration of the photocatalytic member containing fluorine-containing titanium oxide even under high temperature and high humidity conditions To provide a method for operating an air purification device provided with a photocatalytic member containing titanium oxide.
A photocatalytic member containing at least fluorine-containing titanium oxide, a light source that irradiates ultraviolet rays, and an air purification device equipped with a fan. And the photocatalytic member is cooled when the surface temperature of the photocatalytic member becomes a predetermined value or more.
[Selection figure] None

Description

  The present invention relates to a method for operating an air purification apparatus provided with a photocatalytic member containing fluorine-containing titanium oxide.

  In recent years, photocatalytic members containing titanium oxide have been put into practical use in various situations for purposes such as sterilization, deodorization, and antifouling. The place of use is not limited to the outdoors where it is easy to secure the amount of light required for the catalytic reaction, and it can be used indoors where it is difficult to secure the amount of light by providing a light source in the vicinity of the photocatalytic member.

  For example, in order to sufficiently develop the catalytic reaction of the photocatalytic member in an indoor device for the purpose of sterilization, deodorization, etc., a light source (ultraviolet lamp) may be installed in the device. However, when the activity of titanium oxide is low, it is necessary to increase the output of the light source, and the running cost increases. Therefore, development of a photocatalytic member containing titanium oxide having high activity has been performed.

As a method for enhancing the activity of a photocatalytic member containing titanium oxide, it has been proposed that a photocatalytic member containing titanium oxide contains fluorine (for example, Patent Document 1, Patent Document 2, and Patent Document 3).
JP 2002-28494 A JP 2002-136878 A JP 2003-226554 A

  Generally, on the surface of fluorine-containing titanium oxide, the fluorine content in titanium oxide decreases due to an exchange reaction between chemically bonded fluorine and moisture contained in the air. Since the above exchange reaction is a reversible reaction that occurs relatively easily, if the fluorine-containing titanium oxide is left for a long period of time under high temperature and high humidity conditions, the fluorine content in the titanium oxide decreases, and as a result, the activity of the photocatalytic member increases. There is a problem of lowering. In particular, in an apparatus in which a photocatalytic member containing fluorine-containing titanium oxide and a light source are housed together, the light source increases the surface temperature of the photocatalytic member containing fluorine-containing titanium oxide and further promotes a decrease in fluorine content. It will be. In the above-mentioned conventional method, the activity of the photocatalytic member containing titanium oxide can be improved by fluorine, but the device operation method that can cope with the above-mentioned problem in consideration of the characteristics of the photocatalytic member containing fluorine-containing titanium oxide Was not proposed at all, and the high activity of the photocatalytic member could not be sustained for a long time.

  In addition, when the photocatalytic member containing fluorine-containing titanium oxide is not irradiated with ultraviolet rays for a long time, the surface of the photocatalytic member is covered with a chemical substance floating in the air. The high deodorizing performance of the photocatalytic member could not be exhibited.

  The present invention solves the above-mentioned conventional problems, and is an air purification device equipped with a photocatalytic member containing fluorine-containing titanium oxide that can suppress a decrease in fluorine content even under high-temperature and high-humidity conditions. The purpose is to provide a driving method.

  In order to solve the above-mentioned conventional problems, an operation method of an air purification device of the present invention is an air purification device comprising a photocatalytic member containing fluorine-containing titanium oxide, a light source for irradiating ultraviolet rays, and a fan. In the operation method, the photocatalytic member is intermittently irradiated with ultraviolet rays at predetermined time intervals during the operation stop period.

  With this configuration, even if a chemical substance floating in the atmosphere is adsorbed to the photocatalytic member, the adsorbed chemical substance can be decomposed by intermittent irradiation of ultraviolet rays, so that the reduction in the deodorizing ability of the photocatalytic member is suppressed. High deodorizing performance can be maintained over a long period of time.

  According to the operation method of the air purification device of the present invention, it is possible to prevent deterioration of the photocatalytic member containing fluorine-containing titanium oxide even when the air purification device is not used for a long period of time.

  Furthermore, even when operating under high-temperature and high-humidity conditions, the decrease in fluorine content can be suppressed, so that the high activity of the photocatalytic member containing fluorine-containing titanium oxide can be maintained for a long period of time.

  The “photocatalytic member” in the present invention refers to a substance that exhibits catalytic activity when irradiated with light such as ultraviolet rays. Specifically, by irradiating with light, various organic substances and inorganic substances can be decomposed and removed and sterilized, such as decomposition and removal of malodorous components such as acetaldehyde and mercaptans, fungi and algae. It means a substance that can be suitably used for sterilization removal, oxidative decomposition removal of nitrogen oxides, and imparting an antifouling function by making the glass superhydrophilic.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
<Module for Deodorizing Performance Evaluation of Photocatalytic Member 3>
FIG. 1 is a diagram showing a module for evaluating the deodorizing performance of the photocatalytic member 3 according to Embodiment 1 of the present invention. The activity evaluation of the photocatalytic member 3 in Embodiment 1 is performed by measuring the deodorizing performance with respect to acetaldehyde using the above module.

  As shown in FIG. 1, the module for evaluating the deodorizing performance of the photocatalytic member 3 according to the first embodiment includes a box 1 (made of acrylic, internal volume 100 L), a measuring device housing 2, a stirring fan 4, a black light. It is comprised by the blue fluorescent lamp 5, the thermocouple 7, and the control apparatus (not shown).

  A measuring device housing 2 and a stirring fan 4 are installed inside the box 1, and a photocatalytic member 3 (60 mm × 60 mm) is inserted inside the measuring device housing 2. A fan 6 is provided at the lower part of the measuring device housing 2 so that the gas in the box 1 passes through the photocatalytic member 3.

Directly above the photocatalytic member 3, five black light blue fluorescent lamps 5 (6W, manufactured by Matsushita Electric Industrial Co., Ltd.) are installed at intervals of about 50 mm, and a probe (UVS365, USHIO INC.) Is installed. The distance to the photocatalytic member 3 is adjusted in advance so that the intensity of light upon irradiation is 1.0 mW / cm ² . A thermocouple 7 is installed on the surface of the photocatalytic member 3 to detect the surface temperature of the photocatalytic member 3.

  A control device (not shown) is provided outside the box 1 and turns off the black light blue fluorescent lamp 5 when the thermocouple 7 detects that the surface temperature of the photocatalytic member 3 has reached a predetermined value. Or, the operation of the fan 6 is stopped.

<Deodorizing performance evaluation experiment of photocatalytic member 3>
The experiment for measuring the deodorizing performance by the photocatalytic member 3 is performed by the following method.

  While the dry air having a relative humidity of 5% or less is introduced into the box 1, the inside of the box 1 is replaced with dry air by rotating the stirring fan 4 for about 30 minutes. Thereafter, 1.80 L of nitrogen-diluted acetaldehyde 524 ppm standard gas is introduced into box 1 so that the acetaldehyde concentration in box 1 is about 10 ppm. Immediately after the introduction of acetaldehyde, the stirring fan 4 is stopped.

  At substantially the same time as the stirring fan 4 is stopped, the black light blue fluorescent lamp 5 is turned on and the fan 6 of the measuring device housing 2 is rotated. After rotation of the fan 6, a gas chromatograph (GC-14B, manufactured by Shimadzu Corporation) equipped with an automatic sampling device every 3 minutes is started. Sampling is performed for 1 hour at a frequency of 1 sampling / 3 minutes. In the gas chromatograph, Gaskuropack 56 (manufactured by GL Sciences Inc.) is used as a column.

  In Embodiment 1, the deodorizing ability of the photocatalytic member 3 is the sum of the adsorption deodorizing ability by the adsorbent and the decomposition and deodorizing ability by the photocatalytic member 3, and the larger the deodorizing rate coefficient, the better the deodorizing ability. Evaluate as being. Here, the “deodorization rate coefficient” is defined as an absolute value of the slope of a logarithmic approximation of the time change of the acetaldehyde concentration. The deodorization rate coefficient is calculated using the acetaldehyde concentration by dividing the adsorption deodorization ability and the decomposition deodorization ability. In Embodiment 1, in order to accurately evaluate the decomposition and deodorizing ability of the photocatalytic member 3, not the acetaldehyde concentration from 0 minutes to 3 minutes after the start, but the acetaldehyde concentration from 3 minutes to 15 minutes after the start. Was used.

<Method for measuring the concentration of fluorine contained in titanium oxide>
The measurement of the fluorine concentration contained in titanium oxide, which is one of the constituent elements of the photocatalytic member 3 in Embodiment 1, is performed by the following method.

  An automatic sample combustion apparatus using tungsten trioxide (60 mg) as a combustion aid added to the weighed photocatalytic member 3 (about 5 to 8 mg) and argon (200 ml / min) and oxygen (400 ml / min) as combustion gases (AQF-100, manufactured by Dia Instruments Co., Ltd.) is heated to 1080 ° C. The gas generated thereby is absorbed in an absorbing solution composed of a mixed aqueous solution of hydrogen peroxide (900 mg / L) and sodium carbonate (3 mM), and the concentration of fluoride ions in the absorbing solution is determined by ion chromatography ( ICS-1500, manufactured by Nippon Dionex Co., Ltd.).

  In the ion chromatography method, an eluent composed of a mixed solution of sodium carbonate (2.7 mM) and sodium hydrogen carbonate (0.3 mM), a guard column AG12A and a separation column AS12A (manufactured by Nippon Dionex Co., Ltd.) are used. The fluoride ion concentration is measured by detecting the conductivity.

  FIG. 2 is a graph showing the correlation between the concentration of fluorine contained in the titanium oxide and the deodorization rate coefficient according to Embodiment 1 of the present invention. In FIG. 2, as the photocatalytic member 3, the photocatalytic member 3 containing titanium oxide having a fluorine concentration of 0 wt%, 1.3 wt%, and 3.76 wt% was used.

  As shown in FIG. 2, the fluorine concentration and the deodorization rate coefficient are in a substantially proportional relationship. The decrease in the fluorine concentration means a decrease in the deodorization rate coefficient of the photocatalytic member 3, and is not preferable. For example, the deodorization rate coefficient of the photocatalytic member 3 containing titanium oxide containing 3.76% by weight of the fluorine concentration. Is 0.0163, indicating a high numerical value. Assuming that the lower limit of the allowable deodorization rate decrease is 0.013 corresponding to 80% of the value of the above deodorization rate coefficient, the fluorine concentration contained in the titanium oxide is 2.5 wt. % Or more is preferable.

  Examples will be described below.

<Example A>
In this example A, a photocatalytic member 3 containing titanium oxide containing 3.76% by weight of fluorine with respect to titanium oxide was used, a predetermined temperature (25 ° C, 40 ° C, 60 ° C), After placing in a constant temperature and humidity chamber (PL-2KP, manufactured by Espec Corp.) set to relative humidity (30%, 50%, 90%) for 72 hours, the fluorine concentration contained in titanium oxide was measured.

  FIG. 3 is a temperature and humidity profile of the photocatalytic member 3 in the constant temperature and humidity chamber in Example A. As shown in FIG. 3, the storage start time in Example A was set immediately after the photocatalytic member 3 reached both the predetermined set temperature and set humidity (after 1 hour).

<Evaluation A>
FIG. 4 shows the fluorine concentration contained in the titanium oxide after the constant temperature and humidity experiment when the fluorine concentration 3.76 wt% before the constant temperature and humidity experiment is taken as 100. In Example A, when the fluorine concentration after the constant temperature and humidity experiment is 95 ≦ the fluorine concentration after the constant temperature and humidity experiment ≦ 100, it is considered that the fluorine concentration has not changed, and the determination is “◯”. did. On the other hand, when the fluorine concentration after the constant temperature and humidity experiment was 95> the fluorine concentration after the constant temperature and humidity experiment, it was considered that the fluorine concentration was decreased, and the determination was “x”.

  As shown in FIG. 4, under the conditions where the set temperature of the constant temperature and humidity chamber is 40 ° C. or less, the fluorine concentration was 95 or more at all relative humidity, and the determination was “◯”. On the other hand, under the condition where the set temperature of the constant temperature and humidity chamber is 60 ° C., the fluorine concentration is 95 or more when the relative humidity is 30% and the determination is “◯”, but the fluorine concentration when the relative humidity is other than that. Was about 90, and the judgment was “x”.

  From the above, it was found that the decrease in fluorine concentration can be suppressed even under high temperature and high humidity by keeping the surface temperature of the photocatalytic member 3 containing fluorine-containing titanium oxide lower than a predetermined value.

<Example B>
In Example B, an experiment for evaluating the deodorizing performance of the photocatalytic member 3 was performed. As the photocatalytic member 3 in Example B, titanium oxide containing 3.76% by weight of fluorine with respect to titanium oxide, a filter containing zeolite (manufactured by Tosoh Corporation), glass fiber as a substrate, and A colloidal silica (manufactured by Nissan Chemical Industries, Ltd.) as a binder was used. Acetaldehyde was used as the gas for the catalytic reaction.

  FIG. 5 is a flowchart of the deodorization performance evaluation experiment of the photocatalytic member 3 in Example B. As shown in FIG. 5, the deodorizing performance evaluation experiment of the photocatalytic member 3 in Example B is performed once a day (24 hours) under the various conditions described later. The experiment was carried out for 14 days at a frequency of (experimental time of about 1 hour).

(Example 1)
Twelve hours after the start of the deodorization test, the black light blue fluorescent lamp 5 was turned on, and the photocatalytic member 3 was irradiated with ultraviolet rays at an intensity of 1.0 mW / cm ² for 30 minutes. In the time zone other than the deodorization test time (about 1 hour) and the ultraviolet irradiation time (30 minutes), the black light blue fluorescent lamp 5 was turned off.

(Example 2)
Six hours after the start time of the deodorization test, the black light blue fluorescent lamp 5 was turned on, and the photocatalytic member 3 was irradiated with ultraviolet rays at an intensity of 1.0 mW / cm ² for 30 minutes. Further, 6 hours after the ultraviolet irradiation start time, the black light blue fluorescent lamp 5 was turned on again, and the photocatalytic member 3 was irradiated with ultraviolet rays at an intensity of 1.0 mW / cm ² for 30 minutes. In Example 2, this 6-hour cycle including the ultraviolet irradiation time (30 minutes) was repeated three times a day. In the time zone other than the deodorization test time (about 1 hour) and the ultraviolet irradiation time (30 minutes × 3 times), the black light blue fluorescent lamp 5 was turned off.

(Example 3)
Three hours after the start of the deodorization test, the black light blue fluorescent lamp 5 was turned on, and the photocatalytic member 3 was irradiated with ultraviolet rays at an intensity of 1.0 mW / cm ² for 30 minutes. Further, 3 hours after the ultraviolet irradiation start time, the black light blue fluorescent lamp 5 was turned on again, and the photocatalytic member 3 was irradiated with ultraviolet rays at an intensity of 1.0 mW / cm ² for 30 minutes. In Example 3, the cycle every 3 hours including this ultraviolet irradiation time (30 minutes) was repeated 7 times a day. In the time zone other than the deodorization test time (about 1 hour) and the ultraviolet irradiation time (30 minutes × 7 times), the black light blue fluorescent lamp 5 was turned off.

Example 4
In Example 4, when the surface temperature of the filter reached 40 ° C., the fan was blown. Other than that, it carried out similarly to the said Example 1.

(Example 5)
In Example 5, when the surface temperature of the filter reached 40 ° C., the black light blue fluorescent lamp 5 was turned off. Other than that, it carried out similarly to the said Example 1.

(Comparative Example 1)
The photocatalytic member 3 was made of commercially available titanium oxide not containing fluorine (SSP-25, manufactured by Sakai Chemical Industry Co., Ltd.) and zeolite. In Comparative Example 1, during the 24-hour deodorization performance evaluation experiment, only the deodorization test was performed, and no ultraviolet irradiation was performed.

(Comparative Example 2)
As the photocatalytic member 3, the photocatalytic member 3 containing fluorine-containing titanium oxide used in Examples 1 to 5 was used. In this comparative example 2, during the 24-hour deodorization performance evaluation experiment, only the deodorization test was performed, and no ultraviolet irradiation was performed.

<Evaluation B>
In Table 1, the initial deodorizing performance for acetaldehyde in Example B, the deodorizing performance for acetaldehyde immediately after the 14-day deodorizing performance evaluation experiment, and 14 days when the fluorine concentration 3.76% by weight before the experiment is 100 Shows the fluorine concentration immediately after the deodorization performance evaluation experiment. The deodorizing performance of the photocatalytic member 3 in Example B is performed by converting the deodorizing ability in the 6 tatami room from the result obtained using the module for evaluating the deodorizing performance of the photocatalytic member 3 shown in FIG. It was.

  As shown in Table 1, in Examples 1 to 3, the deodorizing performance of the photocatalytic member 3 was maintained even after 14 days, although the fluorine concentration immediately after the 14-day deodorizing performance evaluation experiment was slightly reduced.

  In Examples 4 and 5, by cooling the filter when the temperature reached 40 ° C., not only the high deodorization performance of the photocatalytic member 3 was maintained even after 14 days, but also a 14-day deodorization performance evaluation experiment. Immediately after that, the fluorine concentration was maintained with almost no decrease, and a more favorable result was obtained.

  On the other hand, in Comparative Example 1, the deodorizing performance was low, and in the first deodorizing test, the deodorizing performance for acetaldehyde was less than 90% / h. Accordingly, Comparative Example 1 was excluded from the comparison target of the deodorization performance evaluation experiment of the 14-day cycle, and the experiment was not performed.

  In Comparative Example 2, the initial deodorizing performance for acetaldehyde satisfied 90% / h, but the results were not satisfied immediately after the 14-day deodorizing performance evaluation experiment.

  The operation method of the air purification device according to the present invention can maintain the high activity for a long time by suppressing the deterioration of the photocatalytic member containing fluorine-containing titanium oxide and the decrease in the fluorine concentration. It is useful for an apparatus that is used for a long time under high temperature and high humidity conditions for the purpose of air purification.

The figure which shows the deodorizing performance evaluation module of the photocatalytic member which concerns on Embodiment 1 of this invention. The graph which shows the correlation with the fluorine concentration contained in the titanium oxide which concerns on Embodiment 1 of this invention, and a deodorizing rate coefficient The figure of the temperature and humidity profile of the photocatalytic member in the constant temperature and humidity chamber in Embodiment 1 of this invention Graph of fluorine concentration contained in titanium oxide after experiment in Embodiment 1 of the present invention Flowchart of the deodorizing performance evaluation experiment of the photocatalytic member in Embodiment 1 of the present invention

Explanation of symbols

1 Box 2 Measuring Device Housing 3 Photocatalytic Member 4 Stirring Fan 5 Black Light Blue Fluorescent Lamp 6 Fan 7 Thermocouple

Claims (6)

A method for operating an air purification device comprising a photocatalytic member containing fluorine-containing titanium oxide, a light source for irradiating ultraviolet rays, and a fan,
A method for operating an air purification apparatus, wherein the photocatalytic member is irradiated with ultraviolet rays intermittently at predetermined intervals during an operation stop period. The method of operating an air purification device according to claim 1, wherein the photocatalytic member is cooled when a surface temperature of the photocatalytic member becomes a predetermined value or more. The method of operating an air purification device according to claim 2, wherein the photocatalytic member is cooled when the surface temperature of the photocatalytic member exceeds 40 ° C. The method of operating an air purification device according to claim 2 or 3, wherein the photocatalytic member is cooled by the fan. The method of operating an air purification device according to claim 2 or 3, wherein the method of cooling the photocatalytic member stops the operation of the light source that irradiates the ultraviolet rays. 6. The method for operating an air purification device according to claim 1, wherein the fluorine content of the photocatalytic member is 2.5% by weight or more based on the amount of titanium oxide.

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