JP4538600B2 - Photocatalytic activity evaluation and measurement method and equipment for it - Google Patents

Description

  The present invention relates to a method for evaluating and measuring the activity of a photocatalyst such as titanium dioxide, which is used for various applications such as antifouling, antifogging, sterilization, and decomposition of harmful substances, and an apparatus therefor. More specifically, the present invention relates to a method for evaluating and measuring the activity of a photocatalyst utilizing a photoreduction reaction of silver ions, and an apparatus therefor. More specifically, the present invention relates to a method for evaluating and measuring the activity of a photocatalyst used for an activation evaluation test of a photocatalyst such as titanium dioxide used by being coated on a substrate such as glass, and an apparatus therefor.

  In recent years, various reactions using photocatalysts have been actively studied and actively used in various fields. Among the utilization technologies that are particularly attracting attention, photocatalysts are acted on by various light sources including natural light, and are used for decomposing dirt substances, odorous substances, various floating bacteria, harmful substances, etc. in the air. Attention has been focused on a technique for cleaning the window glass and the outer wall of the building from dirt without the need for human intervention. For this reason, various photocatalysts have been proposed and developed. However, active research and development have been conducted on systems that effectively use photocatalysts. As research and development and application research of such photocatalysts become active, it is important to accurately know and evaluate the performance of the photocatalyst, in particular, the activity of the catalyst, and a standard for that purpose has been demanded. Therefore, various trials, proposals have been made and implemented as photocatalyst evaluation / measurement methods.

  In general, in the case of solid catalysts including photocatalysts, the catalyst activity is measured by measuring the specific surface area of the solid catalyst powder and collecting various data according to the actual reaction to evaluate the performance. It is performed by such as. For example, as a method for evaluating a photocatalyst, a measurement method is known in which the catalyst powder is exposed to light such as formaldehyde and irradiated with light, and the formaldehyde concentration is detected and measured to know and evaluate the degree of decomposition of formaldehyde. .

  However, such an evaluation method is an extremely complicated and time-consuming evaluation method, and if the catalyst to be used is used in a powder state, it is not a powder unlike actual use conditions. In this case, for example, when the photocatalyst is used after being coated and coated on the surface of a substrate such as glass, it is problematic to apply the measurement method based on the powder method because it does not conform to the actual use of the catalyst.

  That is, the coated film-like photocatalyst has an extremely small effective surface area acting as a photocatalyst compared to the powder form, and such a case where extremely high sensitivity and accurate data are required for photocatalytic activity measurement. Measurement and evaluation by applying the powder method is far from the actual use of the catalyst, it is not appropriate, and it is difficult to say that the catalyst activity of the coating film is correctly evaluated. The measured values do not reflect the actual usage of the catalyst, have a problem in sensitivity, and it is extremely difficult and problematic to evaluate the catalyst by this test method.

  Therefore, as an evaluation / measurement method of the activity of the photocatalyst suitable for a form such as a coating film, the following two evaluation methods can be exemplified. The first evaluation / measurement method is a dye decomposition method using a dye such as methylene blue. In this dye decomposition method, the dye is applied to the surface of the photocatalyst material in advance, and the photocatalytic activity is measured by recording the change in absorbance of the dye over time while irradiating it with excitation light of photocatalytic reaction such as ultraviolet light. This is a technique to be realized (see Non-Patent Document 1).

Compared to the powder method, which is the formaldehyde decomposition method, the evaluation method by the first dye method is the actual use situation in that the conditions for measuring the activity of the catalyst and the measurement situation capture the reaction on the catalyst surface. It can be said that this is a very effective evaluation method. However, when introducing the measurement process, first, a step of applying and drying a dye in advance is essential. The state of this dye-coated film is very sensitive to environmental conditions such as the coating process, operator's skill level, temperature and humidity, and it is difficult to always set uniform conditions, which is sufficient in terms of reproducibility. However, it was a lot of work.

  The second method is an evaluation method using silver ion photoreduction. This evaluation method is an evaluation method introduced and reported in the academic literature issued prior to this application (see Non-Patent Document 2). This evaluation method is performed as follows. First, a photocatalytic material is inserted into an aqueous silver nitrate solution, and excitation light irradiation of a photocatalytic reaction such as ultraviolet light is performed. Since silver ions in the aqueous solution start to deposit as a silver thin film on the surface of the photocatalytic material by photocatalysis, the visible light transmittance of the sample decreases with the formation of the silver thin film. After carrying out excitation light irradiation of the photocatalytic reaction for a certain period of time, a sample is taken out from the silver nitrate aqueous solution and transferred to a visible light transmittance measuring device, and visible light is irradiated to measure visible light transmittance. After the measurement, the sample is again inserted into the silver nitrate aqueous solution, and the same operation, that is, the process of irradiation with photocatalytic reaction such as ultraviolet light and the measurement of visible light transmittance is repeated, and the change with time is recorded. Since the visible light transmittance decreases with the formation of the silver thin film, the photocatalytic activity is evaluated from the rate (rate) of the visible light transmittance decrease.

  This latter evaluation method is basically the same as the first method described above, unlike the dyeing method, which maintains the conditions of the coating process, etc. uniformly and is difficult to always manage under constant conditions with high reproducibility. This is an excellent method that requires only control of the purity of water and the concentration of silver nitrate, is very easy to manage and has good reproducibility. Furthermore, this latter technique has advantages such as high sensitivity, subtle activity intensity detection for each sample, and low photocatalytic activity detection limit and high sensitivity. However, the process requires repeating a number of different operations, so it is not always a simple method and problematic because it requires a great deal of time and effort to measure a single sample. .

  In other words, the above-mentioned process of “inserting a sample into an aqueous silver nitrate solution and performing excitation light irradiation of a photocatalytic reaction such as ultraviolet light for a certain period of time” and “visible light transmittance measuring device by taking out the sample from the aqueous silver nitrate solution” It is necessary to repeat the process of “measuring the visible light transmittance by” repeatedly. In addition, since it is necessary for the operator to perform the work in a repetitive manner at all times, the labor required for measuring one sample is very large, and it is a technique that can supply highly sensitive and reliable data. However, it was not a simple method.

“Industrial Materials Vol. 46 No. 5” (1998), Kazuyuki Takami, Takayoshi Nakasone, Kazuhito Hashimoto, Akira Fujishima, Nikkan Kogyo Shimbun, pages 102-105) S. Nishimoto, B .; Ohtani, H .; Kajiwara, T .; Kagiya, J .; Chem. Soc. , Faraday Trans. , 179, 2685 (1983)

As described above, the photocatalytic activity evaluation / measurement method based on the silver ion photoreduction method is a method for evaluating the activation of a film-like photocatalyst made of titanium dioxide applied or coated on a substrate such as glass. Is an extremely effective evaluation means because it is highly sensitive and can be evaluated with good reproducibility regardless of the skill of the analyst. Following the process of irradiating the excitation light for a certain period of time, “the process of taking the sample from the silver nitrate aqueous solution and transferring it to the visible light transmittance measuring device and measuring the visible light transmittance” is alternately repeated several tens of times. It was. In other words, this work is very time-consuming and inefficient, and the preponderance of measurement is offset by the complexity of this work, which is one of the reasons that hindered the development of evaluation methods using this method. It is done. The present invention pays attention to the advantages of the silver ion photoreduction method, and in carrying out the evaluation method by this method, the work steps required per sample are shortened while maintaining the advantages. The present invention aims to provide a method that is simpler than other competing photocatalytic activity measurement methods and capable of accurate measurement with less work time as well as the silver ion photoreduction method.

  Therefore, while basing on the basic matters of the conventional silver ion photoreduction method, the inventors have intensively studied whether the labor required for the analysis can be reduced as much as possible. As a result, in the photocatalytic activity evaluation test method based on the silver ion photoreduction method, conventionally, the photocatalytic activity evaluation was performed independently, and after the reaction by the excitation light irradiation to excite the photoreaction. Rather than carrying out visible light irradiation to obtain the light transmittance separately, it was devised to irradiate all at once and carry out photocatalytic reaction and light transmittance measurement work on the spot with the irradiated light. Advanced.

  Therefore, when the sample was irradiated with light for exciting the photocatalytic reaction and light for measuring the light transmittance at once, the light reaction was caused and the light transmittance was measured while the sample was left in the reaction solution. I was also successful. That is, the photocatalytic reaction by light that excites the photocatalytic reaction, that is, the reaction of reducing silver ions to deposit a silver layer in the form of a catalyst layer, and at the same time measuring the transmittance of visible light transmitted through the cell and the sample. Development of a technique that can be completed, and it is only necessary to repeat this light irradiation and light transmittance measurement work every time, freeing from the complexity of taking out samples one by one and switching the light source each time And succeeded in developing an evaluation and measurement method that can be easily automated to evaluate and measure the photocatalytic activity.

  That is, the sample is photoreacted in a solution for photocatalytic reaction as in the conventional method, and then the sample is taken out and transferred to another means, where the light transmittance is measured. The sample can be left in the same container without the need for complicated operations such as putting in or switching between the light that excites the photoreaction and the light that measures the transmittance and irradiating them separately. In this way, we have succeeded in developing an extremely simplified photocatalytic activity evaluation and measurement method that basically requires only light irradiation and transmittance measurement without taking them out.

  In other words, the conventional method uses only two types of light irradiation processes at different timings, which are two types of light sources: excitation light irradiation that excites the photoreaction and visible light irradiation that determines the light transmittance thereafter. The photocatalytic reaction is caused at the same time as the transmittance can be measured, and the work was simplified and the activity of the photocatalyst was evaluated and measured. This invention is made | formed based on the said knowledge and a series of success, The structure is as the following (1) to (12).

(1) In the photocatalytic activity evaluation / measurement method based on the silver ion photoreduction method, a carrier made of a light transmissive material having a photocatalyst coated and supported on a surface is filled in a light transmissive cell filled with an aqueous solution containing silver ions. Then, the photocatalytic reaction excitation wavelength light and the light transmittance measurement wavelength light are integrated into one system and irradiated to the support from the outside of the cell, and silver is irradiated on the photocatalyst coating surface by the excitation light. A photocatalytic activity evaluation / measurement method characterized in that an ion reduction reaction is caused, and at the same time, the transmittance of light passing through a carrier is measured and detected by measurement light.
(2) The photocatalytic activity evaluation / measurement method according to (1), wherein the photocatalytic reaction excitation wavelength light is ultraviolet light, and the light transmittance measurement wavelength light is visible light.
(3) The photocatalytic activity evaluation / measurement method according to (1), wherein the means for irradiating the wavelength light for photocatalytic reaction excitation and the wavelength light for light transmittance measurement in a single system is a half mirror.
(4) The photocatalytic activity evaluation / measurement method according to (1), wherein the cell and the photocatalyst support are made of transparent glass or synthetic resin having high light transmittance.
(5) The light transmittance was measured from the light irradiation to calculate the catalyst activity, and the process management, data management, and data calculation until the determination were controlled by a computer and automatically performed. (1) The photocatalytic activity evaluation / measurement method described.
(6) The photocatalytic activity evaluation / measurement method according to any one of (1) to (5), wherein the photocatalyst is titanium dioxide.

(7) In a photocatalyst evaluation / measurement apparatus based on a silver ion photoreduction method, light from a first light source that oscillates photocatalytic reaction excitation wavelength light and light from a second light source that oscillates light transmittance measurement wavelength light Are integrated into one system of light, a light transmission reaction cell filled with an aqueous solution containing silver ions, and a light incident surface standing and immersed in the light transmission reaction cell. By a silver ion photoreduction method, comprising: a photocatalyst carrier made of a transparent material coated with a photocatalyst; and a light transmittance measuring device for detecting light transmitted through the photocatalyst carrier and the light transmission type cell. Photocatalyst evaluation / measurement equipment.
(8) The photocatalyst evaluation / measurement device based on the silver ion photoreduction method according to (7), wherein the photocatalytic reaction excitation wavelength light is ultraviolet light, and the light transmittance measurement wavelength light is visible light.
(9) Irradiating the light from the first light source that oscillates the wavelength light for photocatalytic reaction excitation and the light from the second light source that oscillates the wavelength light for light transmittance measurement together into one system of light The photocatalyst evaluation / measurement device by the silver ion photoreduction method according to (7), wherein the means to perform is a half mirror.
(10) The photocatalytic activity evaluation / measurement device according to (7), wherein the light transmission type reaction cell and the photocatalyst carrier are made of transparent glass or synthetic resin having high light transmittance.
(11) The light transmittance was measured from the light irradiation to calculate the catalyst activity, and the process management, data management, and data calculation until the determination were controlled by a computer and automatically performed. (7) The photocatalytic activity evaluation / measurement apparatus described.
(12) The photocatalytic activity evaluation / measurement device according to any one of (7) to (11), wherein the photocatalyst is titanium dioxide.

In the conventional silver ion photoreduction method, a photocatalytic reaction is induced by ultraviolet light irradiation for a certain period of time to grow a silver thin film on the sample surface (several seconds to several minutes), and the visible light transmittance of the sample is increased. The step of measuring (several tens of seconds to several minutes) was performed with separate devices. Therefore, automation is difficult, and the above two steps are repeated by the number of data points required by the operator. For this reason, in the case of high-precision evaluation that requires a large number of data points, the above two steps were repeated every few hours. More specific work contents: Insert sample into silver nitrate aqueous solution → Irradiate photocatalytic reaction excitation light for a certain period of time → Remove sample and remove aqueous solution → Install sample in measuring device of visible light transmittance → Visible light transmittance measurement → The cycle of taking out the sample and inserting it into the aqueous silver nitrate solution was performed for the number of data points. If the data is 20 points, it is repeated 20 times.
In contrast, according to the present invention, as described above, the excitation light source for photocatalytic reaction and the light source for visible light transmittance measurement are integrated into one system, so that photocatalytic reaction induction and visible light transmittance measurement by excitation light irradiation can be performed. At the same time, the amount of work for the operator is drastically reduced. The work performed by the operator when evaluating one sample is to place the sample in a quartz cell → fill the quartz cell with an aqueous silver nitrate solution → install the quartz cell in a post-spectral ultraviolet / visible spectroscopic device, transmittance measuring device, etc. → control • Start up a program that repeats visible light measurement for a certain period of time using a data storage computer. This is a one-time operation regardless of the number of data points. This is because the light source for excitation of photocatalytic reaction and the light source for visible light transmittance measurement are integrated into one system, which eliminates the need to move the sample between devices, and can benefit from automatic repeated measurement by a computer. is there. Comparing the amount of work with the conventional one, it can be seen that the amount of work of the present invention is small and reasonable.

  The present invention will be specifically described with reference to the drawings and examples. However, these are only specific examples for disclosing as an aid for understanding the present invention, and the present invention is not limited thereto.

  FIG. 1 is a schematic diagram of a photocatalytic activity evaluation apparatus that integrates an excitation light source and a visible light transmittance measurement light source and implements the photocatalytic activity measurement evaluation method of the present invention and shows the concept of the apparatus. Effective for both photocatalytic reaction excitation and visible light transmittance measurement using a half mirror with light from light source 1 that oscillates wavelength light for photocatalytic reaction excitation and light from light source 2 that oscillates wavelength light for visible light transmittance measurement Synthesize light 4 that unifies light.

  Of course, depending on the combination of the photocatalyst material and the light source, there may be a case where a single light source can be used to excite the photocatalytic reaction and to generate light effective for measuring the visible light transmittance. In this case, a configuration using only a single light source (not shown) is also effective.

  First, the photocatalyst to be evaluated is coated on the surface of the substrate 8 such as glass by various means to form the photocatalyst layer 7. This sample layer 7 is placed in a cell 5 made of a material permeable to both photocatalytic reaction excitation light made of quartz filled with an aqueous silver nitrate solution 9 and the like and light for measuring visible light transmittance, as shown in the figure. Light including photocatalytic reaction excitation light and visible light transmittance measurement light is irradiated from the outside of the quartz cell. The irradiated light is installed so as to pass through the quartz cell 5, the silver nitrate aqueous solution 9, the photocatalyst coating film 7, the glass substrate 8, the silver nitrate aqueous solution 9, and the quartz cell 5 in this order. When installing the sample upside down, the photocatalytic reaction excitation light 1 is absorbed in the photocatalyst coating film 7, and the amount of light contributing to the photocatalytic reaction on the surface of the photocatalyst coating film is reduced, resulting in sensitivity. In the worst case, it is not preferable because it causes measurement failure.

  Although this method has been described based on a coating film, it goes without saying that the photocatalyst used is also effective for bulk samples. It should be noted that the photocatalytic activity can be measured as long as visible light is transmitted.

  As described above, the sample installation is completed, and immediately after the start of irradiation of light 4 including both photocatalytic reaction excitation and visible light transmittance measurement, photocatalytic reaction (in this case, silver ions in silver nitrate aqueous solution 9 (not shown)). The formation of the silver thin film 6 by the reduction of is just started, the visible light transmittance is high, and the light beam 10 that has passed through the quartz cell is hardly absorbed, so the transmittance (light intensity) measurement detector 11 is used. The intensity of the measured visible light is strong, and the intensity immediately after the start of irradiation is defined as 100%, which is automatically recorded in the control / data storage computer 12.

The transmittance (light intensity) measurement detector 11 and its control / data storage computer 12 are set to automatically measure and record the intensity of visible light at regular intervals immediately after the start of irradiation. Formation of the silver thin film 6 by reduction of silver ions (not shown) proceeds on the surface of the photocatalyst coating film 7 irradiated with effective light 4 including both photocatalytic reaction excitation and visible light transmittance measurement over time. To do. Since the silver thin film hinders the transmission of visible light, the intensity of the light beam 10 passing through the quartz cell decreases as the thickness of the silver thin film increases. That is, the visible light transmission intensity (transmittance) decreases with respect to the measurement elapsed time, and the state is recorded by the transmittance (light intensity) measurement detector 11 and the control / data storage computer 12. The higher the photocatalytic activity of the coating film, the faster the rate of formation of the silver thin film 6 due to reduction of silver ions (not shown), and the faster the intensity of visible light 10 passing through the quartz cell decreases. That is, the rate of decrease in the intensity of the visible light 10 passing through the quartz cell corresponds to the photocatalytic activity of the coating film 7 to be evaluated.

  Furthermore, it is currently widely used as a photocatalyst material, and is generally widely available for photocatalytic activity evaluation of a titanium dioxide photocatalytic thin film coated on a transparent substrate such as glass, which has the highest need for photocatalytic activity evaluation. The post-spectral ultraviolet / visible spectroscopic device and the transmittance measuring device 13 can be employed as the means for realizing the present invention without any modification. Here, the post-spectral type ultraviolet / visible spectroscopic device or transmittance measuring device is a spectroscopic device or a transmittance measuring device for ultraviolet / visible light, and all the light beams of all wavelength ranges emitted by the light source are simultaneously applied to the sample. In the case of irradiating and performing spectroscopy, a spectroscopic device or a transmittance measuring device of a type for performing light emitted from a sample is referred to as a post-spectral ultraviolet / visible spectroscopic device or a transmittance measuring device.

  In this type of apparatus, the sample is always irradiated with light from ultraviolet to visible, so that the progress of the photocatalytic reaction and the transmittance measurement can proceed simultaneously. Although not particularly limited, an example of a post-spectral type ultraviolet / visible spectroscopic device is a Multispec 1500 type manufactured by Shimadzu Corporation. When this commercially available apparatus is used, the apparatus for carrying out the present invention can measure the photocatalytic activity of a sample if it has a post-spectral ultraviolet / visible spectroscopic apparatus 13, a quartz cell 5, a silver nitrate aqueous solution 9 and the like.

Example;
The case where the present invention is applied to the photocatalytic activity measurement of a titanium dioxide coating thin film actually formed on a glass substrate by sputtering is shown as an example.
The sample is a titanium dioxide coating thin film formed on a glass substrate using a sputtering apparatus. The thickness of the glass substrate 8 is 0.5 millimeters, and the thickness of the titanium dioxide coating layer 7 is about 400 nanometers. This sample was inserted into a quartz cell having an optical path length of 2 mm and filled with an aqueous silver nitrate solution having a concentration of 0.01 mol / liter. In this example, a post-spectral ultraviolet / visible spectroscopic device 13 (manufactured by Shimadzu Corp., Multispec 1500 type), which is commercially available and of which quality is uniform and guaranteed, was used as a device that combines light irradiation and transmittance measurement. From the light source configuration of the apparatus, a deuterium lamp is used as the light source 1 mainly responsible for the photocatalytic reaction excitation, and a halogen lamp is used as the light source mainly responsible for the visible light transmittance measurement. The sample was synthesized via the mirror 3 and irradiated toward the quartz cell 5 containing the samples 7 and 8 and the silver nitrate aqueous solution 9.

  After this, the spectroscopic ultraviolet / visible spectroscopic device 13 is provided with a light source control mechanism (not shown), which ensures that the wavelength, intensity, and amount of light emitted from the light source are always maintained stably. Light irradiation is performed with accuracy, and the reliability of the present invention is ensured. That is, in the practice of the present invention, if the light irradiation conditions fluctuate, the obtained data will be unreliable, so it is very important to select one that does not fluctuate the light irradiation conditions. is there. In the case of this example, the ultraviolet intensity at the quartz cell position was measured with a Minolta UM-10 + UM-360 type ultraviolet light intensity measuring device, and found to be 3 microwatts / square centimeter. The stability and reproducibility were sufficient. Furthermore, there is no change in terms of transmittance measurement in that the factor is more important than the stability of the light source. Therefore, the device 11 for measuring the transmittance is important in carrying out the invention and evaluating the catalyst, and it should not be an exaggeration to say that it is a heart, but a highly reliable device should be prepared.

The obtained measurement data is centrally managed by the computer 12, and the activity of the photocatalyst is automatically calculated and obtained. As described above, the working procedure of the present invention is greatly simplified as compared with the conventional method, and the time required to calculate and obtain the photocatalytic activity after the sample is set in the quartz cell is extremely shortened. It was done. Moreover, while it was difficult to automate the conventional method, the present invention can be automated, so the burden on the measurer is greatly reduced.

  FIG. 2 shows the photocatalytic activity measurement results for a glass substrate having no photocatalytic active coating layer for comparison with a glass substrate having a photocatalytic active coating. In FIG. 2, the horizontal axis represents the measurement time (different from the work time. In the present invention, the work is from the sample setting to the program activation, and the subsequent measurement is automatically performed by the spectroscopic device). Shows the rate. Of course, a simple glass substrate does not exhibit photocatalytic activity, and the transmittance is constant at the 100 percent position. However, with respect to the coated sample, the transmittance of the sample decreases due to the deposition of a silver thin film due to the photocatalytic effect. It can be seen that the image is very clearly and highly sensitive. In addition, the continuity of the measurement points proved that the stability of the light source was extremely high, and it was proved that the measurement results were highly reliable.

  The number of measurement points was 600 points (5 times per minute) for a measurement time of 120 minutes. In the conventional measurement method of the conventional silver ion photoreduction method, usually one cycle of work is always required to obtain one measurement point (insert the sample into the silver nitrate aqueous solution → irradiate the photocatalytic reaction excitation light for a certain period of time → remove the sample and the aqueous solution. → Place the sample in the visible light transmittance measurement device → Visible light transmittance measurement → Take out the sample → Insert into the silver nitrate aqueous solution, even if skillful, irradiation time etc. can not be cut down at least 5 minutes per cycle Therefore, the amount of work when trying to take this data by the conventional method is an unrealistic number of 5 minutes × 600 = 50 hours.

  As described above, the present invention is capable of dramatically reducing the amount of work (time) of an operator required for evaluating one sample, as compared with the conventional silver ion photoreduction method, The significance is extremely great. In summary, according to the present invention, as described above, the photocatalytic reaction excitation light source and the visible light transmittance measurement light source are integrated into a single system, so that photocatalytic reaction induction and visible light transmission by excitation light irradiation are integrated. The rate measurement is performed at the same time, and the amount of work for the worker is drastically reduced. The work performed by the operator when evaluating one sample is to place the sample in a quartz cell → fill the quartz cell with an aqueous silver nitrate solution → install the quartz cell in a post-spectral ultraviolet / visible spectroscopic device, transmittance measuring device, etc. → control • Start up a program that repeats visible light measurement for a certain period of time using a data storage computer. This is a one-time operation regardless of the number of data points. This is because the light source for excitation of photocatalytic reaction and the light source for visible light transmittance measurement are integrated into one system, which eliminates the need to move the sample between devices, and can benefit from automatic repeated measurement by a computer. is there. Comparing the amount of work with the conventional one, it can be seen that the amount of work of the present invention is small and reasonable.

  In the conventional silver ion photoreduction method, it was necessary to maintain the working time of measurement of one sample at a realistic value, so at most it is called high-precision measurement with a data point of about several tens of plots per sample. I have done it. However, according to the present invention, the number of data points is irrelevant to the work time, and only depends on the calculation speed and storage capacity of the control / data storage computer. With a recent computer, the present invention greatly increases the conventional method not only in dramatically shortening the working time but also in measuring accuracy because it does not hinder the number of data points per sample from several hundreds or more. Surpass.

Furthermore, it is currently overwhelmingly widely used as a photocatalyst material, and for the photocatalytic activity evaluation of a titanium dioxide photocatalyst thin film coated on a transparent substrate such as glass that has the highest need for photocatalytic activity evaluation, it is generally widely marketed after spectroscopic analysis. It is also a great advantage that the type ultraviolet / visible spectroscopic device and the transmittance measuring device (13) can be adopted as the whole means for realizing the present invention without any modification. Currently, photocatalytic materials are widely studied in many research institutions and private companies all over the world. However, research on photocatalyst materials is relatively new, and objective and quantitative evaluation criteria for photocatalytic activity have not yet been established, and the present situation is that photocatalytic activity is evaluated by different methods and apparatuses for each institution. That is, under the present situation, there is no objective standard when comparing photocatalytic activity with an external engine, so it is extremely difficult to compare catalytic activity.

  Conditions required for the evaluation method and apparatus that can be an objective standard for this photocatalytic activity evaluation are high accuracy and high sensitivity, good reproducibility, no operator dependency and no environment dependency, simple (working time, (Measurement time is short), and a measuring device with exactly the same specifications can be easily obtained. The present invention sufficiently satisfies these conditions, and is likely to be adopted as a global standard in the future as a photocatalytic activity evaluation / measurement method.

  As technology using light becomes popular, research and development of photocatalysts are expected to become increasingly popular. Thus far, there has been no appropriate evaluation method unified with respect to photocatalytic activity, which has been a factor that hinders the development of photocatalysts. The significance of providing a measurement method is extremely great. In the future, the present invention will be greatly utilized for research and development of photocatalysts, and it is expected to greatly contribute not only to its development but also to industrial development.

The schematic diagram of the photocatalytic activity evaluation and measurement apparatus of this invention which integrated the light source for excitation of a photocatalytic reaction, and the light source for visible light transmittance | permeability measurement. The figure which shows the catalytic activity measurement result of the film-form titanium dioxide photocatalyst coated on the glass substrate.

Explanation of symbols

1: Photocatalytic reaction excitation light source.
2: Visible light transmittance measurement light source.
3: Half mirror.
4: 1 and 2 combined light from each light source.
5: Quartz cell.
6: Silver thin film deposited by photocatalytic reaction.
7: Coating layer showing photocatalytic effect.
8: Substrate such as glass.
9: Silver nitrate aqueous solution.
10: Synthetic light from each light source whose intensity decreased due to absorption by the silver thin film.
11: Transmittance (light intensity) measurement detector.
12: Computer for control and data storage.
13: Post-spectral ultraviolet / visible spectroscopic / transmittance measuring device.

Claims (12)

  In the photocatalytic activity evaluation and measurement method by the silver ion photoreduction method, a support made of a light-transmitting material with a photocatalyst coated and supported on a surface is placed in a light-transmitting cell filled with an aqueous solution containing silver ions, and immersed. Then, from the outside of the cell, the photocatalytic reaction excitation wavelength light and the light transmittance measurement wavelength light are integrated into one system and irradiated with light, and the silver ion reduction reaction is performed on the photocatalyst coating surface by the excitation light. The photocatalytic activity evaluation / measurement method is characterized in that the transmittance of light passing through the support is measured and detected by measuring light at the same time.   The photocatalytic activity evaluation / measurement method according to claim 1, wherein the photocatalytic reaction excitation wavelength light is ultraviolet light, and the light transmittance measurement wavelength light is visible light.   The photocatalytic activity evaluation / measurement method according to claim 1, wherein the means for irradiating the wavelength light for photocatalytic reaction excitation and the wavelength light for light transmittance measurement in a single system is a half mirror.   The photocatalytic activity evaluation / measurement method according to claim 1, wherein the cell and the photocatalyst carrier are made of transparent glass or synthetic resin having high light transmittance.   2. The photocatalyst according to claim 1, wherein the catalyst activity is calculated by measuring the light transmittance from the light irradiation, and the process management, data management, and data calculation until obtaining are controlled by a computer and automatically performed. Activity evaluation and measurement method.   The photocatalytic activity evaluation / measurement method according to any one of claims 1 to 5, wherein the photocatalyst is titanium dioxide.   In the photocatalyst evaluation / measurement apparatus based on the silver ion photoreduction method, the light from the first light source that oscillates the wavelength light for photocatalytic reaction excitation and the light from the second light source that oscillates the wavelength light for light transmittance measurement are combined. Means for integrating and irradiating with one system of light, a light-transmitting reaction cell filled with an aqueous solution containing silver ions, and a photocatalyst on the light incident surface standing and immersed in the light-transmitting reaction cell. Photocatalyst evaluation by silver ion photoreduction method, comprising a photocatalyst carrier made of a transparent material applied, and a light transmittance measuring device for detecting light transmitted through the photocatalyst carrier and the light transmission type cell measuring device.   The photocatalyst evaluation / measurement device by the silver ion photoreduction method according to claim 7, wherein the photocatalytic reaction excitation wavelength light is ultraviolet light, and the light transmittance measurement wavelength light is visible light.   Means for collectively irradiating the light from the first light source that oscillates the wavelength light for photocatalytic reaction excitation and the light from the second light source that oscillates the light transmittance measurement wavelength light into one system of light; The photocatalyst evaluation / measurement device according to claim 7, wherein the photocatalyst is a half mirror.   The photocatalytic activity evaluation / measurement device according to claim 7, wherein the light transmission type reaction cell and the photocatalyst support are made of transparent glass or synthetic resin having high light transmittance.   The photocatalyst according to claim 7, wherein the light transmittance is measured from the light irradiation to calculate the catalyst activity, and the process management, data management, and data calculation until the calculation are controlled by a computer and automatically performed. Activity evaluation and measurement device. The photocatalytic activity evaluation / measurement device according to any one of claims 7 to 11, wherein the photocatalyst is titanium dioxide.