Photocatalyst loaded body, method for manufacturing photocatalyst loaded body, and fluid treatment apparatus using photocatalyst loaded body

Abstract

[Problem] The present invention addresses the problem of providing: a photocatalyst loaded body which has good adhesion to a glass substrate, is not susceptible to falling off of a photocatalyst layer even when used for a water treatment, and can avoid an increase in cost for loading, and which also eliminates the need for surface roughening of the glass substrate, can efficiently irradiate the photocatalyst layer with ultraviolet rays or the like, and enables a photocatalytic reaction to sufficiently proceed; and a fluid treatment apparatus which uses this photocatalyst loaded body. [Solution] A photocatalyst layer 5 is composed of: an aggregate 50 of titanium oxide crystals which are obtained by hydrolyzing titanium(IV) tetrabutoxide by heat on a surface 4a of a glass substrate 4; and titanium oxide particles 51 which have an average particle diameter of 1 µm or less and are loaded on the surface 4a together with the aggregate 50 of the titanium oxide crystals using the aggregate 50 of the titanium oxide crystals as a binder.

Description

Photocatalyst carrier, method for manufacturing photocatalyst carrier, and fluid treatment device using photocatalyst carrier

[0001] The present invention relates to a photocatalyst carrier having a photocatalyst layer carrying a photocatalyst that causes a photocatalytic reaction when exposed to ultraviolet light, and treating a fluid that comes into contact with the photocatalyst through the photocatalytic reaction, and to a fluid treatment device using the same.

[0002] As an example of this type of photocatalyst carrier and fluid treatment device, a water purification device has been proposed that includes a glass substrate that supports a photocatalyst and has a photocatalytic reaction surface that comes into contact with a fluid, and a light-emitting diode that is arranged so as to be able to irradiate the photocatalyst and that mainly emits a predetermined visible light and ultraviolet light with a wavelength of 360 to 400 nm (see Patent Document 1).Methods for supporting the photocatalyst on the glass substrate include a method in which a colloid (sol) of titanium oxide particles is applied to the substrate surface and then baked, a vacuum deposition method, and a chemical deposition method using a gas-phase reaction (vapor phase growth method).

[0003] However, when titanium oxide particles are supported by coating and baking, the adhesion is generally poor, and particularly when used for fluid treatment as in Patent Document 1, there are issues that the adhesion is likely to decrease due to water erosion and the photocatalytic layer is likely to peel off due to water pressure, etc. Furthermore, vacuum deposition methods and vapor phase growth methods require large-scale equipment, which poses a cost issue.

[0004] In response to this, it is possible to improve adhesion by roughening the surface of the glass substrate as a pretreatment for loading. However, when the glass substrate is roughened, when ultraviolet rays or the like are irradiated from the back (the surface opposite to the photocatalyst-loaded surface), the ultraviolet rays are scattered by the roughened unevenness, and the ultraviolet rays cannot be efficiently supplied to the photocatalyst layer, and the photocatalytic reaction cannot be fully exerted. Furthermore, when ultraviolet rays are irradiated from the front (the loading surface side), the ultraviolet rays are reflected and scattered in the process of passing through water, and similarly, the ultraviolet rays cannot be efficiently supplied to the photocatalyst layer, and there is a problem that the photocatalytic reaction cannot be fully exerted.

[0005] Japanese Patent Application Laid-Open No. 2004-50174

[0006] Therefore, in view of the above-mentioned situation, the present invention aims to solve the problem of providing a photocatalyst carrier that has good adhesion to a glass substrate, the photocatalyst layer is unlikely to fall off even when used in fluid treatment, and can avoid increased costs during support, and that does not require roughening of the glass substrate, and that can efficiently irradiate ultraviolet rays etc. onto the photocatalyst layer, thereby enabling the photocatalytic reaction to be fully exerted, as well as a fluid treatment device using the same.

[0007] The present invention encompasses the following: (1) A photocatalyst carrier for fluid treatment, having a photocatalyst layer supported on the surface of a glass substrate that comes into contact with a fluid, the photocatalyst layer carrying a photocatalyst that undergoes a photocatalytic reaction when exposed to ultraviolet light, and treating the fluid that has come into contact with the photocatalyst layer by photocatalytic reaction, the photocatalyst layer comprising aggregates of titanium oxide crystals formed by thermal hydrolysis of titanium (IV) tetrabutoxide on the surface, and titanium oxide particles having an average particle size of 1 μm or less that are supported on the surface together with the aggregates of titanium oxide crystals, using the aggregates of titanium oxide crystals as a binder. Here, "average particle size" refers to the particle size at 50% of the integrated value in a particle size distribution determined by a laser diffraction / scattering method.

[0008] (2) The photocatalyst carrier according to (1), wherein the titanium oxide particles have an average particle size of 20 to 40 nm.

[0009] (3) The photocatalyst carrier according to (1), wherein the glass substrate is made of borosilicate glass.

[0010] (4) A method for producing a photocatalyst carrier for fluid treatment, which has a photocatalyst layer carrying a photocatalyst that undergoes a photocatalytic reaction when exposed to ultraviolet light on the surface of a glass substrate that comes into contact with a fluid, and which treats the fluid that has come into contact with it by a photocatalytic reaction, comprising the steps of: preparing a mixed solution by mixing titanium oxide particles having an average particle size of 1 μm or less with an alcohol dilution of titanium (IV) tetrabutoxide; applying the mixed solution to the surface of the glass substrate that comes into contact with the fluid; hydrolyzing the titanium (IV) tetrabutoxide in the mixed solution by heating at 150°C or higher to form an aggregate of titanium oxide crystals; and thereby forming the photocatalyst layer, in which the titanium oxide particles are carried on the surface together with the aggregate of titanium oxide crystals, using the aggregate of titanium oxide crystals as a binder.

[0011] (5) The method for producing a photocatalyst carrier according to (4), wherein the concentration of titanium (IV) tetrabutoxide in the mixed solution is 2% to 5%.

[0012] (6) The method for producing a photocatalyst carrier according to (4), wherein the mixed solution is applied to the surface of the glass substrate that has been heated to 150°C or higher in advance, thereby hydrolyzing titanium (IV) tetrabutoxide in the mixed solution.

[0013] (7) The method for producing a photocatalyst carrier according to (4), wherein the weight ratio of titanium (IV) tetrabutoxide to titanium oxide particles in the mixed solution ((weight of titanium (IV) tetrabutoxide) / (weight of titanium oxide particles)) is 0.5 to 3.

[0014] (8) A fluid treatment device comprising: a photocatalyst carrier according to any one of (1) to (3); a fluid supply means for bringing the fluid into contact with the surface of the photocatalyst carrier in a stationary or flowing state; and a light irradiation unit for irradiating ultraviolet light onto the photocatalyst of the photocatalyst layer through the glass substrate from the side of the photocatalyst carrier that is not in contact with the fluid.

[0015] The photocatalyst carrier according to the present invention obtained as described above has good adhesion of the photocatalyst layer even without roughening the glass substrate in advance, and it is possible to efficiently irradiate the photocatalyst layer on the front side with ultraviolet light from the back side. Furthermore, due to its good adhesion, it can be used without problems as a fluid treatment device. Furthermore, when carrying the photocatalyst, no large-scale equipment such as vacuum deposition or vapor phase growth is required, and cost increases can be avoided.

[0016] 1 is a perspective view showing a fluid treatment device using a photocatalyst carrier according to a representative embodiment of the present invention; 2 is an exploded perspective view of the fluid treatment device; 3 is a longitudinal cross-sectional view of the fluid treatment device from the side; 4 is a longitudinal cross-sectional view of the fluid treatment device from the front; 5 is an explanatory diagram showing the procedure for supporting a photocatalyst layer; 6 is an explanatory view showing another embodiment of a photocatalyst carrier and a fluid treatment device; 7 is a longitudinal cross-sectional view of the fluid treatment device; 8 is an explanatory view showing yet another embodiment of a photocatalyst carrier and a fluid treatment device; 9 is a longitudinal cross-sectional view of the fluid treatment device; 10 is an STM photograph of the surface of the photocatalyst layer of the photocatalyst carrier; 11 is an STM photograph of the surface of the photocatalyst layer of the photocatalyst carrier; 12 is a photograph showing the weight change before and after support in Example 1 and Comparative Examples 1 and 2; 13 is a photograph showing the results of a tape peeling test in Example 1 and Comparative Examples 1 and 2; 14 is a graph showing the results of an acetaldehyde odor test; 15 is a photograph showing the weight change before and after a water immersion and water-running test in Example 1 and Comparative Examples 1 and 2; 16 is a photograph showing the state of the water immersion test; 17 is a photograph showing the results of the water-running test in Example 1 and Comparative Examples 1 and 2. Graphs showing the results of a formalin decomposition test and a phenol decomposition test.

[0017] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0018] 1 to 4, a fluid treatment device 1 according to the present invention comprises a photocatalyst carrier 2, a fluid supply means 3 for bringing the fluid into contact with the surface of the photocatalyst carrier 2 in a stationary or flowing state, and a light irradiating unit 9 for irradiating ultraviolet light onto the photocatalyst in the photocatalyst layer through the glass substrate from the side of the photocatalyst carrier 2 that is not in contact with the fluid. Note that, in the following embodiment, an example of treatment of water as the fluid (for example, treatment of ammonia in fish breeding water or treatment of industrial wastewater) will be described, but the fluid is not limited to water and can be applied to treatment of various fluids that are treated by photocatalytic reactions in a photocatalyst layer, such as various liquids, air, gases, etc.

[0019] The photocatalyst carrier 2 has a glass substrate 4 and a photocatalyst layer 5 on the surface 4a of the glass substrate 4 that comes into contact with the fluid, the photocatalyst layer 5 carrying a photocatalyst that undergoes a photocatalytic reaction when exposed to ultraviolet light. For the glass substrate 4, quartz glass, high silica glass, or borosilicate glass is preferred in terms of strength, but ordinary soda-lime glass or the like can also be suitably used. In this example, the glass substrate 4 is formed in the shape of a flat plate, but is not limited to a specific shape or structure, and may of course be curved or flat, and may also be formed in any shape other than a plate, such as a tubular (cylindrical) or spherical shape.

[0020] The photocatalytic layer 5 is composed of an aggregate 50 of titanium oxide crystals formed by thermal hydrolysis of titanium (IV) tetrabutoxide on the surface, and titanium oxide particles 51 having an average particle diameter of 1 μm or less that are supported on the surface together with the aggregate of titanium oxide crystals, using the aggregate of titanium oxide crystals as a binder.

[0021] Although the titanium oxide particles 51 have high photocatalytic reactivity, they are repelled by the surface 4a of the unroughened glass substrate 4 alone, resulting in extremely low adhesion. Even if they do adhere, they are limited to those that happen to be embedded in pores that happen to be open on the glass surface. On the other hand, the titanium oxide crystal aggregates 50 of titanium (IV) tetrabutoxide adhere to the surface 4a of the unroughened glass substrate 4, but because each crystal structure is large and the bonds between the crystals are weak, they are easily peeled off as a crystal when subjected to force such as water pressure. They also have low photocatalytic reactivity.

[0022] In contrast, by combining the two as in the present invention, their mutual affinity allows the titanium oxide crystals of titanium(IV) tetrabutoxide to function as a binder supporting the titanium oxide particles 51. Furthermore, the titanium oxide particles 51 also function as a binder that strengthens the bonds between the crystals by penetrating between the titanium(IV) tetrabutoxide crystals, preventing the crystalline units from peeling off. This prevents the titanium(IV) tetrabutoxide crystals from falling off together with the titanium oxide particles 51, and eliminates the need for surface roughening of the glass substrate 4, allowing the formation of a photocatalytic layer 5 with good photocatalytic reactivity.

[0023] As shown in Figure 5, the method for producing a photocatalyst carrier involves first preparing a mixed solution by mixing titanium oxide particles with an average particle size of 1 µm or less with an alcohol-diluted solution of titanium (IV) tetrabutoxide (S101). The concentration of titanium (IV) tetrabutoxide in the mixed solution is 2% to 5%. The particle size of the titanium oxide particles 51 is preferably 7 to 100 nm, and more preferably 20 to 70 nm. If the particle size is too small, ultraviolet light, decomposition substances, and adsorption substances will not reach the inside of the photocatalyst layer 5, and it is thought that improvement in catalytic function will not be expected. The weight ratio of titanium (IV) tetrabutoxide to titanium oxide particles in the mixed solution is 0.5 to 3.

[0024] Next, this mixed solution is applied to the surface 4a of the glass substrate 4 (S102), and the titanium (IV) tetrabutoxide in the mixed solution is hydrolyzed by heating at 150°C or higher (S103). By applying the mixed solution to the surface of the glass substrate that has been heated to 150°C or higher in advance, the titanium (IV) tetrabutoxide in the mixed solution can be efficiently hydrolyzed.

[0025] This hydrolysis causes titanium (IV) tetrabutoxide to become an aggregate of titanium oxide crystals, and together with the aggregates, the photocatalytic layer carrying titanium oxide particles 51 is formed (S104).

[0026] 10 and 11 are STM photographs of a photocatalytic layer 5 formed on the surface of a glass substrate 4. Numerous titanium (IV) tetrabutoxide crystals have formed on the substrate surface. Titanium oxide particles 51 are also attached to and cover the periphery of the crystals. Because the titanium oxide particles in the photographs are 7 nm in diameter, they do not appear as grains, but can be recognized as hazy white regions around the titanium (IV) tetrabutoxide crystal surfaces and between the crystals (particularly the crystals indicated by the circles in FIG. 11 are heavily attached). In this way, the titanium oxide particles 51 are firmly supported on the surface of the glass substrate 4 via the titanium (IV) tetrabutoxide crystals, and also function as a binder that strengthens the bond between the titanium (IV) tetrabutoxide crystals.

[0027] As shown in FIG. 2, the photocatalyst carriers 2 configured in this manner are provided in a pair at the front and rear of a frame 6 for a housing, which is made up of an upper plate 61, side plates 62 and 63, and a bottom plate 64, so as to close the front and rear openings 6a and 6b, and each photocatalyst carrier 2 is attached to the openings 6a and 6b with the front side on which the photocatalyst layer 5 is formed facing the inside of the frame 6 for a housing.

[0028] Water 14 to be treated is supplied by a fluid supply means 3 into the interior of the housing frame 6 to which each photocatalyst carrier 2 is attached, and the water 14 is treated by the photocatalytic reaction of the photocatalytic layer 5 of the front and rear photocatalyst carriers 2 facing the interior space. In other words, the interior space S1 of the housing frame 6 becomes a treatment section that treats the water 14 with the photocatalyst.

[0029] As shown in Figures 1 to 4, the fluid supply means 3 is composed of a container 30 located below for storing the water to be treated 14, a pumping passage 33 consisting of a pumping pipe 32 whose upper end is connected to an opening 64a formed in the bottom plate 64 of the housing frame 6 and whose lower end is connected to a pumping pump 31 arranged within the container 30, and a return flow path 35 consisting of a return pipe 34 whose one end is connected to openings 62a, 63a formed at an upper position of the internal space S1 in the left and right side plates 62, 63 of the frame 6 and whose other end extends into the container, for returning the water 14 supplied to the internal space S1 through the pumping passage 33 back to the container 30.

[0030] The water 14 to be treated, supplied to the lower part of the internal space S1 through the pumping path 33, flows upward through the internal space S1, is treated by a photocatalytic reaction caused by the photocatalyst carrier 2 in the process, is then returned to the container 30 from an upper position through the return path 35, and is supplied again to the internal space S1 through the pumping path 33, thereby repeatedly undergoing treatment by photocatalytic reaction. The opening in the upper plate 61 is an open hole 61a that opens the upper space of the internal space S1 to the atmosphere and is configured to take in and discharge air, thereby maintaining a constant water pressure and allowing the water 14 to circulate smoothly through the pumping path 33 and the return path 35.

[0031] The supply of water 14 through the pumping channel 33 may be continuous or intermittent. The supply speed and timing can be appropriately set by controlling the pumping pump 31 depending on the type of treatment. In this example, water is supplied to the internal space S1 from below and returned from above, but this is not limiting. Water may be supplied from above and returned from below, or an appropriate wall may be provided in the internal space S1 to form a longer return channel, with the pumping channel and return channel connected at both ends of the channel.

[0032] When a return flow path is provided in the internal space S1 in this way, it is preferable that the walls extend parallel to the front-rear direction and are formed so that the front and rear photocatalyst carriers 2 always face the inside of the flow path. Alternatively, a wall parallel to the glass substrate 4 can be provided in the center, and the flow can be formed so that after flowing along the front side and being treated by the front photocatalyst carrier, it turns back and flows along the rear side and is treated by the rear photocatalyst carrier.

[0033] In this embodiment, the housing frame 6 having the photocatalyst carrier 2 is supported above by a gate-shaped support frame 11, and water is circulated between the housing frame 6 and the container 30 provided below, but this positional relationship is not limited to this. Also, although water circulates vertically in the internal space S1, it is of course possible to turn the housing frame 6 sideways and have the water flow horizontally.

[0034] The light irradiation unit 9 is configured so that LED substrates 90 having ultraviolet LED light sources 91 are arranged in parallel at intervals on the back side (outside the opposite side from the internal space S1) of each photocatalyst carrier 2, and ultraviolet light is transmitted from the back side through the glass substrate 4 of the photocatalyst carrier 2 to irradiate the photocatalyst in the photocatalyst layer 5 on the front side. The LED substrates 90 are attached to the inner side facing the photocatalyst carrier 2 of a metal support plate 92 that extends vertically and has a bent U-shaped cross section, and are configured so that heat generated by the ultraviolet LED light sources 91 can be dissipated from the support plate 92 to the outside.

[0035] To further promote heat dissipation, a metal cover plate 80 extending vertically and similarly bent in a U-shaped cross section is provided on the outside of the light irradiation unit 9. A gap S2 extending vertically is formed between the cover plate 80 and the outer surface of the support plate 92, and is configured to allow outside air to be introduced / exhausted from upper and lower openings 80a, 80b. A through-hole 80c is formed in the approximate center of the cover plate 80 to allow outside air to be introduced / exhausted from the gap S2, and an electric fan 82 is provided to introduce / exhaust air through the through-hole 80c. This allows the heat generated by the light irradiation unit 9 to be efficiently dissipated to the outside.

[0036] 6 and 7 show another embodiment of the fluid treatment device 1 according to the present invention. The fluid treatment device 1 of this embodiment comprises a photocatalyst carrier 2 having a photocatalyst layer 5 provided on the outer peripheral surface of a peripheral wall 41 of a beaker-like glass substrate 4 having a bottom plate, and a light irradiation unit 9 provided inside the glass substrate 4 for irradiating the inner peripheral surface of the peripheral wall 41 with ultraviolet light.

[0037] Then, this photocatalyst carrier 2 is immersed in a container 30 containing water 14 to be treated, with the upper opening 12 above the water surface, thereby treating the water 14 in the container 30 that comes into contact with the photocatalyst layer 5 on the outer circumferential surface. In this way, it is also possible to treat stationary water instead of flowing water.

[0038] 8 and 9 show still another embodiment of the fluid treatment device 1 according to the present invention. The fluid treatment device 1 of this embodiment is configured such that a slider 13 having a U-shaped cross section and a photocatalyst carrier 2 as a bottom plate is provided on a cover plate 301 of a container 30 for water to be treated, inclined at an appropriate angle, and water 14 is supplied to the top of the slider 13 by a water pump 31 and a water pumping pipe 32, and the water is returned to the container 30 from the bottom.

[0039] 9, the photocatalyst carrier 2 has a photocatalyst layer 5 formed on the upper surface of a plate-shaped glass substrate 4, and a light irradiator 9 is arranged in parallel on the back surface of the photocatalyst carrier 2. The photocatalyst layer 5 forming the bottom surface of the slider 13 treats the water flowing over it.

[0040] Although the embodiments of the present invention have been described above, the present invention is not limited to these examples, and can of course be embodied in various forms without departing from the spirit of the present invention. For example, the photocatalyst carrier 2 of this embodiment is used as a component of the fluid treatment device 1, but it is also a preferred embodiment to configure it as a panel such as a glass window panel of a building or a glass panel constituting the wall of a plant cultivation greenhouse, and to install the photocatalyst layer 5 facing indoors, thereby causing a photocatalytic reaction with ultraviolet rays from the sun, and treating (decomposing harmful gases, etc.) the indoor air (fluid) that comes into contact with the photocatalyst layer.

[0041] Next, various tests were conducted on a sample prepared using the following samples: a sample (Example 1) in which aggregates of titanium oxide crystals hydrolyzed by titanium (IV) tetrabutoxide and titanium oxide particles are supported on the surface of a glass plate (without surface roughening) according to the present invention; a sample (Comparative Example 1) in which only aggregates of titanium oxide crystals hydrolyzed by titanium (IV) tetrabutoxide are supported on the surface of the same glass plate; and a sample (Comparative Example 2) in which only titanium oxide particles are supported on the surface of the same glass substrate.The results of these tests will be described below.

[0042] <Samples of Example 1 and Comparative Examples 1 and 2> For the samples of Example 1 and Comparative Examples 1 and 2, a plurality of borosilicate glass plates (without surface roughening treatment and a five-point average surface roughness (Ra) of approximately 0.05 μm) measuring 72 mm in length, 52 mm in width, and 1.2 mm in thickness were prepared.

[0043] For the support treatment of the sample in Example 1, 100 ml of titanium (IV) tetrabutoxide monomer was diluted with ethanol to a concentration of 2%. 4 g of a slurry containing titanium oxide particles (a slurry containing 3% titanium oxide particles with an X-ray particle size of 7 nm ("ST-01" manufactured by Ishihara Sangyo Kaisha, Ltd.) was added to the diluted solution to prepare a mixed solution.

[0044] The glass plate is heated to 150°C to 350°C in advance, and the mixed solution is sprayed onto it. As a result, the ethanol in the mixed solution evaporates on the surface of the glass plate, and titanium (IV) tetrabutoxide is hydrolyzed to form titanium oxide crystals. At the same time, relatively small titanium oxide particles are caught in the titanium oxide crystals and are supported on the glass surface.

[0045] The sample of Comparative Example 1 was subjected to the loading treatment by diluting 100 ml of titanium (IV) tetrabutoxide monomer with ethanol to prepare a 2% diluted solution. A glass plate was then preheated to 150°C to 350°C, and the diluted titanium (IV) tetrabutoxide solution was sprayed onto it. As a result, the ethanol evaporated from the diluted solution on the glass plate surface, and the titanium (IV) tetrabutoxide was hydrolyzed to form titanium oxide crystals, which were then loaded onto the glass surface.

[0046] The sample of Comparative Example 2 was subjected to a supporting treatment by immersing the glass plate in a slurry containing titanium oxide particles at room temperature for 10 seconds and then allowing it to dry naturally.

[0047] <<Tape Peeling Test>> A tape peeling test was performed on each sample of Example 1 and Comparative Examples 1 and 2. First, for each sample of Example 1 and Comparative Examples 1 to 3, the weight of the glass plate before and after loading was measured in advance as shown in Figure 12, and the loading amount was calculated from the difference. The results are shown in Table 1.

[0048]

[0049] The results of the loading amount show that Example 1 loaded twice as much as Comparative Example 1, and that the loading amount increased significantly by mixing titanium oxide particles. The tape used was "Crepe Tape" manufactured by Nichiban Co., Ltd., cut into 15 mm x 30 mm pieces, attached to the surface with a finger, and then immediately peeled off. The results are shown in Figure 13.

[0050] As a result of the tape peeling test, most of the supported titanium (IV) tetrabutoxide titanium oxide crystals and titanium oxide particles were peeled off together with the tape in Comparative Examples 1 and 2, but almost none were peeled off and remained in Example 1. This shows that the photocatalyst layer of the photocatalyst carrier according to the present invention improves both the loading amount and the adhesion.

[0051] <Acetaldehyde Removal Performance Test> Next, the results of an acetaldehyde removal performance test conducted using the samples of Example 1 and Comparative Examples 1 and 2, each prepared by the same support treatment as above, will be described.

[0052] The test method conformed to JIS R 1701-22016, Part 2, "Acetaldehyde Removal Performance," of the Fine Ceramics Photocatalytic Materials Air Purification Performance Test Method. Specific test conditions were: acetaldehyde supply concentration: 5.13 ppm; test gas flow rate: 1.0 L / min; water vapor concentration: 1.56 volume fraction%; temperature: 23.5±1°C; light source: two Toshiba FL10BLB black light blue lamps; ultraviolet irradiance: 10 W / m²; pre-washing and drying conditions: immersion in purified water for two hours, followed by natural drying; pre-washing ultraviolet irradiance and irradiation time: 15 W / m² for 24 hours; and because the sample was filter-like, the test was conducted in a transmission mode (where gas was passed through the through-grooves of the filter-like sample).

[0053] The test equipment used was a precision humidity generator "SRG-1R-1L" manufactured by Daiichi Scientific, a hydrogen flame ionization detector "GC-2014AFF" manufactured by Shimadzu Corporation, a gas blender "GB-2C" from Kofloc, an acetaldehyde concentration analyzer "GC-2014AFF" manufactured by Shimadzu Corporation (lower detection limit 0.5 ppm), a carbon dioxide concentration analyzer "GC-2014AFF" manufactured by Shimadzu Corporation (lower detection limit 0.5 ppm), and a gas sampling autosampler with built-in gas chromatograph.

[0054] The test results are shown in the graph in Figure 14. As can be seen from Figure 14, it was confirmed that an extremely significant photocatalytic effect was obtained according to the present invention (Example 1). As the results of Comparative Example 1 show, the titanium oxide crystals of titanium (IV) tetrabutoxide themselves have almost no photocatalytic activity. However, it can be seen that the presence of titanium oxide crystals allows a large amount of titanium oxide particles to be supported, thereby achieving the above-mentioned significant photocatalytic effect. It is thought that Comparative Example 2 has a smaller amount of titanium oxide particles, resulting in a smaller photocatalytic effect.

[0055] <<Water Immersion & Water Runoff Test>> A water immersion and water runoff test was conducted on each sample of Example 1 and Comparative Examples 1 and 2. After submerging in water for approximately one month, water was runoff at the same flow rate. Each sample was used after the tape peeling test described above, and as shown in Figure 15, the weight was measured before and after the water immersion and water runoff test, and the difference between the weights was used to determine the amount of material removed by the test. The results are shown in Table 2.

[0056]

[0057] As can be seen from the results of the water immersion and water pouring tests in Table 2, in Example 1, the photocatalyst layer hardly fell off even when exposed to water, but in Comparative Example 1, in which only titanium oxide crystals of titanium (IV) tetrabutoxide were supported, more than one-third of the amount supported before the test (12.634 g - 12.577 g = 0.057 g) fell off. In Comparative Example 2, in which only titanium oxide particles were supported, the amount supported before the test was originally small (0.004 g), and it can be seen that most of it fell off. This shows that the photocatalyst layer of the photocatalyst support of the present invention improves both the amount supported and the adhesion in water.

[0058] <<Aqueous Organic Matter Decomposition Test>> Next, the results of a photocatalytic reaction test will be described, in which an aqueous solution containing organic matter (formalin / phenol) was placed in the container 30 using the fluid treatment device 1 shown in Figures 1 to 4 described above. Formalin was prepared by placing 10 L of pure water in a plastic tank and adding 300 μL of special-grade formaldehyde solution manufactured by Junsei Chemical Co., Ltd., to create a formalin solution of approximately 20 ppm.

[0059] The glass plate and photocatalyst layer of the photocatalyst carrier 2 were made of the same components and by the same method as in Example 1 used in the above-mentioned tests, and titanium (IV) tetrabutoxide was hydrolyzed onto the surface of the glass plate to form titanium oxide crystals, and at the same time titanium oxide particles were supported on the surface of the glass plate.

[0060] The container 30 was sealed, and the open hole 61a in the upper plate 61 of the housing frame 6 was also sealed to prevent gas leakage. The photocatalyst layer 5 of the photocatalyst carrier had a carrying area of ​​60 mm x 300 mm, and the light irradiating unit 9 had a total of 36 ultraviolet LEDs (18 on each side), with a supply current of 700 mA. The concentrations of residual formalin and residual phenol in the container were measured using a Kyoritsu Chemical Research Institute Digital Pack Test Multi SP. The test results are shown in the graphs of Figures 18 and 19. Both the organic formalin, which has a chain structure, and phenol, which has a benzene ring structure, were decomposed.

[0061] DESCRIPTION OF SYMBOLS 1 Fluid treatment device 2 Photocatalyst carrier 3 Fluid supply means 4 Glass substrate 4a Surface 5 Photocatalyst layer 6 Housing frame 6a, 6b Opening 9 Light irradiation section 11 Support frame 12 Opening 13 Slider 14 Water 30 Container 31 Water pump 32 Water pumping pipe 33 Water pumping passage 34 Circumferential flow pipe 35 Circumferential flow passage 41 Peripheral wall 50 Aggregate 51 Titanium oxide particles 61 Upper plate 61a Open hole 62, 63 Side plates 62a, 63a Opening 64 Bottom plate 64a Opening 80 Cover plate 80a, 80b Opening 80c Through hole 82 Electric fan 90 LED substrate 91 Light source 92 Support plate 301 Cover plate S1 Internal space S2 Gap

Claims

1. A photocatalyst carrier for fluid treatment, having a photocatalyst layer supported on the surface of a glass substrate that comes into contact with a fluid, where the photocatalyst causes a photocatalytic reaction when exposed to ultraviolet light, and treating the fluid that has come into contact with the photocatalyst through a photocatalytic reaction, wherein the photocatalyst layer is composed of an aggregate of titanium oxide crystals formed by thermal hydrolysis of titanium (IV) tetrabutoxide on the surface, and titanium oxide particles with an average particle size of 1 μm or less that are supported on the surface together with the aggregate of titanium oxide crystals, using the aggregate of titanium oxide crystals as a binder.

2. The photocatalyst carrier according to claim 1, wherein the titanium oxide particles have an average particle size of 20 to 40 nm.

3. The photocatalyst carrier according to claim 1, wherein said glass substrate is made of borosilicate glass.

4. A method for manufacturing a photocatalyst carrier for fluid treatment, which has a photocatalyst layer supported on the surface of a glass substrate that comes into contact with a fluid, and which processes the fluid that has come into contact with it through a photocatalytic reaction when exposed to ultraviolet light, comprising the steps of: preparing a mixed solution by mixing titanium oxide particles with an average particle size of 1 μm or less with an alcohol dilution of titanium (IV) tetrabutoxide; attaching the mixed solution to the surface of the glass substrate that comes into contact with the fluid; hydrolyzing the titanium (IV) tetrabutoxide in the mixed solution by heating at 150°C or higher to form an aggregate of titanium oxide crystals; and forming the photocatalyst layer on the surface, in which the titanium oxide particles are supported together with the aggregate of titanium oxide crystals, using the aggregate of titanium oxide crystals as a binder.

5. The method for producing a photocatalyst carrier according to claim 4, wherein the concentration of titanium (IV) tetrabutoxide in the mixed solution is 2% to 5%.

6. A method for producing a photocatalyst carrier according to claim 4, wherein the mixed solution is applied to the surface of the glass substrate which has been preheated to 150°C or higher, thereby hydrolyzing the titanium (IV) tetrabutoxide in the mixed solution.

7. The method for producing a photocatalyst carrier according to claim 4, wherein the weight ratio of titanium (IV) tetrabutoxide to titanium oxide particles in the mixed solution is 0.5 to 3.

8. A fluid treatment device comprising: a photocatalyst carrier according to any one of claims 1 to 3; a fluid supply means for bringing the fluid into contact with the surface of the photocatalyst carrier in a stationary or flowing state; and a light irradiation unit for irradiating ultraviolet light onto the photocatalyst in the photocatalyst layer through the glass substrate from the side of the photocatalyst carrier that is not in contact with the fluid.

Images