JP2007298328A - Photocatalyst activity evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting and evaluating simply photocatalyst activity on a building execution field, and a portable photocatalyst activity evaluation device therefor, with a background wherein, though, as a method for measuring the photocatalyst activity of a photocatalyst substance, a test material is carried into a laboratory as a sample and evaluated by using full-scale analysis method and analysis equipment, in the case where especially the photocatalyst substance is applied onto the surface of an external material or an internal material for building, there is no means for performing quality confirmation and quality guarantee on the execution field. <P>SOLUTION: A transparent adhesive tape wherein methylene blue is included in a base material is stuck on the external material surface or the like having an applied or included photocatalyst substance, and UV-LED light or visible LED light is irradiated from the surface, to thereby generate a photocatalyst reaction. A decoloration process of methylene blue by a reduction reaction of the photocatalyst is measured as a change with time of reflection intensity of red LED light irradiated to the sample surface as measuring light, and displayed as a digital numerical value, to thereby evaluate the photocatalyst activity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photocatalytic activity evaluation apparatus and a photocatalyst for evaluating and detecting the activity of a photocatalyst on a material surface on which a photocatalytic substance is applied or contained on a building exterior material, interior material, wood surface, etc., and performing quality assurance. The present invention relates to a method for producing a tape-like methylene blue reagent as a reference substance for evaluating activity.

  A photocatalytic substance is a substance which has titanium oxide as a main component and exhibits photocatalytic activity by irradiating the surface of the substance with ultraviolet rays and visible rays. In titanium oxide, electrons in the valence band are excited by ultraviolet or visible light energy to generate electron and hole carriers. Holes take electrons from water molecules in the air and become stable, and water molecules from which electrons have been taken off become hydroxy radicals. On the other hand, electrons cause a reduction reaction with oxygen in the air to generate a superoxide anion. In general, hydroxy radicals and superoxide anions are called active oxygen and have a very strong redox decomposition ability. Harmful substances are decomposed with this decomposition power. Therefore, this photocatalytic reaction provides useful properties such as decomposition of harmful gases, disinfection action, and antifouling action. However, in order to evaluate the activity of these useful photocatalysts, samples had to be taken into the laboratory or laboratory and evaluated over time. In particular, when a photocatalytic substance is applied to an exterior material or interior material, there has been no simple evaluation method and evaluation apparatus for evaluating the activity of the photocatalyst in a short time at the construction site.

As a method for solving this problem, a method for optically measuring a decolorization process due to the reduction action of methylene blue of an organic dye, which is a wet decomposition performance test method proposed as a test method by the Photocatalyst Standardization Committee, is adopted.
Patent Publication 2004-138387 Light quantity detection unit having an activation light source for causing a photocatalyst, a light emitting element for irradiating a predetermined sample with measurement light, and a light receiving element for receiving light that has reached through the sample The photocatalytic function evaluation device evaluates the photocatalytic function based on the result obtained by the light receiving element, the activation light source has a plurality of lamps having different wavelengths, and the light quantity detection unit evaluates the photocatalytic function. A reference sample detector for a sample to be used as a reference and an evaluation sample detector for a sample whose photocatalytic function is to be evaluated, and a plurality of lamps for the reference sample detector and the evaluation sample detector The optical arrangement with respect to is the same. This apparatus has been developed for the purpose of measuring photoactivity by relative comparison with a reference sample, and is suitable for strict photoactivity measurement. However, the measurement apparatus becomes full-scale and cannot be applied to portable detection purposes. It is not suitable for the purpose of easily checking the activity at the construction site where the photocatalyst is installed. Patent publication 2005-313044 An evaluation apparatus that can carry a test photocatalyst coating film and a photocatalyst-containing material quickly and easily and intuitively to a consumer at any place. The contents and lid of the portable box-type case are opened approximately 90 degrees, and the light source is held by the arm that extends from the lid or the side wall of the contents. After irradiating the ink-coated plate and the ink-coated plate or forming a photocatalytic coating film, a coating-coated small piece is placed on the coating plate coated with ink and irradiated with a light source to prevent the photocatalytic coating film. It is an evaluation apparatus for comparing the stain effect visually. Although it is a portable and simple evaluation device, it is not suitable for objective evaluation of any kind of photocatalyst, because it is not detected numerically but visually.

  Photocatalysts based on titanium oxide act under the irradiation of sunlight with moisture adsorbed on the surface, causing oxidation and reduction, so there are two main functions: organic matter degradability and high water wetting performance. It is known for expressing its function. Since this phenomenon can be used to provide building materials having antibacterial, antifungal and antifouling properties, they are widely used in the medical, food distribution and construction industries. The photocatalyst has a higher photoactivity as the concentration of titanium oxide is higher. However, if the concentration is too high, so-called white flower phenomenon occurs, such as precipitation of crystals on the surface. Therefore, the concentration needs to be adjusted, and defective products with very low concentrations are also available. Is a problem. As a method for evaluating the activity of the photocatalyst, three methods of (1) an oleic acid test method, (2) a hydrophilic performance test method, and (3) a wet degradation performance test method have been studied. Of these, the oleic acid test method (1) and the hydrophilic performance test method (2) both irradiate the sample with light, track changes in the water contact angle, and how many times the water contact angle decreases (final contact) It is intended to evaluate the photoactivity from the relationship with the self-cleaning effect of organic matter decomposition. Although it is known that the correlation between the two is good, the sample is brought into the laboratory and generally requires a measurement time of about 48 hours. The wet decomposition performance test method of (3) is a method in which a cylinder is attached to a test piece, a dye aqueous solution (methylene blue) is poured into the cylinder, and the decolorization process due to the reduction reaction is performed using an absorptiometer with the progress of light irradiation. To track. This method can measure from 30 minutes to 1 hour, but you must use a full-scale measuring device that brings the sample into the laboratory and uses an absorptiometer. Not suitable. Under such circumstances, the development of an apparatus for simply evaluating the activity of the photocatalyst at the construction site has been an issue.

  In the present invention, a tape-like thin film is applied to a surface of a material to be inspected that contains or contains a photocatalytic substance, after applying a tape that applies or contains a photocatalytic reactant containing methylene blue as an evaluation standard substance for evaluating photoactivity. Light is transmitted through UV-LED or visible light LED to cause photocatalytic reaction. As the photocatalytic reaction proceeds on the surface of the material to be inspected, decolorization due to the reduction reaction of methylene blue, which is the evaluation reference substance, proceeds. In this decolorization process, red light from a red LED is irradiated as measurement light to methylene blue, and the reflectance of reflected light with respect to the irradiated light is measured. This is a system that evaluates photocatalytic activity by digitally displaying and visualizing measurement results.

  As described above, according to the first and second aspects of the invention, the photocatalytic activity can be evaluated relatively easily and reliably at a construction site or the like. In addition, UV-LED and visible light LED are provided as light sources for photocatalytic activity measurement, and both can be selected and irradiated, so it is possible to evaluate the photocatalytic activity of the material to be inspected against UV light and visible light. Therefore, it is possible to reliably perform quality assurance of the photocatalytic substance in a wide range.

  A photocatalytic substance mainly composed of methylene blue is applied to the surface of the titanium oxide-based photocatalytic substance or a tape containing a photocatalytic reactive substance is applied to the surface, and light is irradiated from the surface to activate the photocatalyst. Advance methylene blue decolorization. In order to optically detect the decolorization process of methylene blue, a red LED spot light is irradiated as measurement light, and the intensity of reflected light from the surface of methylene blue is detected using a photodiode or a phototransistor. Therefore, the photocatalytic activity evaluation device collects and irradiates UV light or visible light on the sample surface, collects the reflected light from the sample surface using an optical fiber, and guides it to the photodetector. It comprises a detector head portion composed of a reflected light receiving portion, and a measuring device main body portion in which reflected light from the detector head portion is connected through an optical fiber. The main body of the measuring device detects the reflected light captured by the optical fiber from the measuring device head, and digitally converts the photovoltaic power output from the detector circuit to display numerically and visually And a power supply circuit unit that supplies a light source unit, a detection circuit unit, and a digital display unit.

  The UV LED and visible light LED used as irradiation light are coaxially arranged in the measuring instrument head portion, and are condensed on the photocatalytic substance to be measured under the same conditions by switching the switch. Red LED light as measurement light is incident perpendicularly to the surface of the methylene blue tape, and reflected light that is vertically reflected in the same arrangement is detected by a photoelectric detector through an optical fiber. The light source circuit and the reflected light detection circuit of the measurement LED are characterized by having a circuit configuration that eliminates the influence of light other than the measurement light by performing pulse modulation.

FIG. 1 is a graph showing the change in reflected light intensity with respect to the light irradiation time, and the three graphs show the results when the light intensity of the UV-LED to be irradiated is strong, medium and weak, respectively. FIG. 2 is a photograph taken of the change in reflected light intensity measured in FIG. 1 as a segment display of a light emitting diode, and shows that the photocatalytic activity can be evaluated in about 1 minute. FIG. 3 is a layout and configuration diagram of the photocatalytic activity evaluation apparatus according to claim 1, and FIG. 4 is a cross-sectional layout diagram of the evaluation apparatus head section.

General building exterior materials, interior materials, exterior materials for transportation equipment such as trucks, coating and impregnation on the surface of interior materials, photocatalytic substances applied and impregnated on the surface of tiles used in various sanitary equipment such as toilets Use for evaluation and quality assurance is expected. It can also be used for evaluation confirmation after these constructions, and evaluation and determination of the degree of deterioration associated with aging.

It is a graph which shows the example of a measurement of the change of the reflected light intensity with respect to light irradiation time. It is the photograph which image | photographed the mode which showed the photocatalytic activity with respect to light irradiation time with the segment display of the light emitting diode. It is a figure which shows arrangement | positioning and a structure of the photocatalyst activity evaluation apparatus concerning this invention. It is sectional drawing which shows arrangement | positioning of an evaluation apparatus head part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photoelectric detector main circuit 2 ... Power supply 3 ... Operation indicator lamp 4 ... Digital display part 5 ... Red LED, photodetector 6 ... UVLED, visible light LED
7 ・ ・ ・ Tape (methylene blue)
8 ... Photocatalytic substance 9 ... Two-core optical fiber 10 ... Evaluation device head cover

Claims (2)

A method for evaluating and detecting the activity of a photocatalyst mainly composed of titanium oxide or the like, wherein (a) the surface of a substance coated with or containing the photocatalyst contains methylene blue as an evaluation standard substance for evaluating the photocatalytic activity A tape containing or containing a photocatalytic reactant is applied. (b) The surface of the tape is irradiated with ultraviolet light or visible light using a UV-LED or visible light LED, and the photocatalytic substance is activated by the ultraviolet light or visible light transmitted through the tape to advance the photocatalytic reaction. (c) The activity of the photocatalytic reaction is determined from the progress of the decolorization process, which is a reduction reaction of methylene blue, which is an evaluation reference substance. (d) In order to measure the decolorization process of methylene blue, the surface of the tape is irradiated with red LED light condensed by an optical fiber as measurement light, and the intensity of the reflected light from the tape is detected by a light intensity detection device. (e) The intensity is numerically digitally displayed and visually displayed in a bar graph form by a light emitting diode to evaluate the activity of the photocatalyst. The photocatalytic activity of the photocatalytic substance used on the surface of tiles, building exterior materials, interior materials, wood, wallpaper, etc. is evaluated by the procedures (a), (b), (c), (d), (e). Evaluation device for detecting. Methylene blue is used as an evaluation reference material for evaluating the photocatalytic activity of the photocatalytic material. In the activity evaluation process, as a means for causing the photocatalytic substance and methylene blue to react closely, a method for applying methylene blue to the surface of the tape-like thin film so that the photoactivity can be accurately detected, and a method for preparing and preparing a methylene blue reagent Activity detection reagent tape.

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