WO2017122823A1

WO2017122823A1 - Solid photocatalytic material formed from solid material constituted only of titanium dioxide having photocatalytic function, method for manufacturing same, and treatment device

Info

Publication number: WO2017122823A1
Application number: PCT/JP2017/001141
Authority: WO
Inventors: 根岸　信彰; 加藤　薫一
Original assignee: 株式会社光触媒研究所; 国立研究開発法人産業技術総合研究所
Priority date: 2016-01-15
Filing date: 2017-01-13
Publication date: 2017-07-20
Also published as: JP2017124388A; JP6082895B1; CN108698020B; CN108698020A

Abstract

The purpose of the present invention is to provide a solid photocatalytic material formed from a solid material (not having a carrier) constituted only of titanium dioxide having a photocatalytic function, a method for manufacturing the same, and a water treatment device. Provided are a solid photocatalytic material, a method for manufacturing the same, and a device, said solid photocatalytic material being formed from a solid material that is constituted only of titanium dioxide that does not include rutile type crystals and comprises anatase type crystals (may include Brookite type crystals), and satisfying each numerical value for i) - vi) in the following: i) pore distribution of 5 - 15 nm, ii) specific surface area of 70 - 110 m²/g, iii) true density of 3.90 ± 1.0 g/cm³, iv) bulk specific gravity of 1.3 - 1.6, v) Vickers harness of 600 - 800 Hv, and vi) crystal grain size of 10 - 25 nm. With the present invention, it is possible to provide a new type of solid photocatalytic material constituted only of titanium dioxide that comprises anatase type crystals that are identical from the outer shell to the inner core of the solid material without the necessity for adding a carrier.

Description

SOLID PHOTOCATALYST MATERIAL COMPRISING SOLID ONLY WITH TITANIUM DIOXIDE HAVING PHOTOCATALYTIC FUNCTION, PROCESS FOR PRODUCING THE SAME

The present invention relates to a solid photocatalyst material comprising a solid material composed only of titanium dioxide having a photocatalytic function, a method for producing the same, and a treatment apparatus. More specifically, the present invention relates to water in response to ultraviolet rays. The present invention relates to a solid photocatalyst material consisting of a solid material (no carrier) composed only of titanium dioxide having a photocatalytic function for environmental purification such as air, a manufacturing method thereof, and a water treatment apparatus using the solid photocatalyst material. is there. The solid photocatalyst material of the present invention is a simple facility / system, particularly in developing countries, where drinking water depends on water such as rivers and ponds. The present invention is useful for providing a new technology that enables the preparation and provision of safe drinking water that is purified and does not proliferate.

Conventionally, photocatalysts that exhibit catalytic action by irradiation with actinic rays such as ultraviolet light and visible light, for example, decompose and remove air purification materials that remove harmful substances, deodorizing materials that decompose bad odors, and organic compounds dissolved in water. It is widely used as a water purification material. The photocatalyst is also applied as an antibacterial material that utilizes the oxidizing action of the photocatalyst, and an antifouling material that prevents contamination of window glass and outer walls.

Conventionally, as a prior art, for example, in Patent Document 1, by utilizing the porosity of silica gel, a silica support in which titanium dioxide is supported up to the inner surface of the silica gel enables high efficiency of photocatalysis. A photocatalyst-supported silica gel is described. However, this type of photocatalyst-supported silica gel is not used in the air layer, but long-term use in water has the problem that the silica support dissolves in water and is lost. However, it is possible to use it, but it is difficult to actually use it for durability.

As another prior art, for example, Patent Document 2 describes a photocatalytic thin film product in which a photocatalyst is immobilized by forming glass beads as a carrier and titanium dioxide as a thin film on the surface thereof. However, this type of photocatalyst thin film is not suitable for actual use requiring a flow rate due to flow path pressure loss when used in a fixed bed when used in water, and the photocatalytic thin film itself is not suitable for use in a fluidized bed. Since they rub against each other and peel off, none of them can be put to practical use.

As another prior art, for example, in Patent Document 3, a photocatalyst product in the form of granules or pellets obtained by compressing and solidifying powdered titanium dioxide is used for treatment of dry cleaning waste liquid. An example is given. However, since this type of photocatalytic product is solidified by solidifying powdered titanium dioxide with pressure, its hardness and anti-destructive strength are limited, and can be used for actual use of the product of the present invention. The quality is greatly different from that of the specific hardness and anti-destructive strength.

As another prior art, for example, Patent Document 4 describes a method for producing a composite material in which a composite material in which calcium phosphate crystals are precipitated on the surface of titanium dioxide is used as a bleaching disinfectant. However, the composite material having this type of carrier is essentially different in structure from the solid photocatalyst material of the present invention comprising a solid material composed only of pure titanium dioxide crystals. It is not suitable for use in applications such as air purification.

As another prior art, for example, Patent Document 5 discloses a purification produced by applying or impregnating a photocatalyst to a continuous fine foam formed by subjecting a carrier such as used glass to continuous porous treatment. The materials are listed. However, the purification material having this type of carrier is significantly different in structure from the solid photocatalyst material of the present invention consisting of solids composed only of pure titanium dioxide, and the content of titanium dioxide crystals Since the product of the present invention is of a minute level that cannot be compared with the product of the present invention, it cannot be a product having excellent water purification / air purification performance as characterized by the solid photocatalyst material of the present invention.

Japanese Patent Application Laid-Open No. 11-138017 “Photocatalytic silica gel and method for producing the same” Applicant: Director, Industrial Technology Institute, Shinto Kogyo Co., Ltd. JP 2001-046883 A “Silica gel molded body having photocatalytic function and method for producing the same” Applicant: Shinto Kogyo Co., Ltd. JP 2002-282704 A “Titanium oxide-supported photocatalyst silica gel and method for producing the same” Applicant: Shinto Buyserax Co., Ltd. Japanese Patent No. 2,883,761 "Bacteria-preventing body" Applicant: Director, Industrial Technology Institute, Photocatalyst Research Institute Co., Ltd. Japanese Patent Application Laid-Open No. 2001-347258 “Industrial waste treatment method, waste liquid treatment apparatus used therein and cleaning apparatus using the same” Applicant: Yamaha Corporation JP 2003-82393 A “Cleaning Material” Applicant: National Institute of Advanced Industrial Science and Technology Utility Model Registration No. 3171431 “Eco-Purification Material” Applicant: PMC Service Co., Ltd.

Generally, titanium dioxide is most often sold in powder form. However, in order to produce a photocatalyst, it cannot be used as it is in powder form, but is fixed to some binder (binder) or carrier, such as solidification with a binder (binder) or support by a carrier. It is necessary to. However, the immobilized powder has a problem that the binder (binder) and the carrier become impurities, and the photocatalytic performance of titanium dioxide cannot be fully exhibited.

In addition, since titanium dioxide formed as a thin film by the sol-gel method is used by being suddenly supported on a plate-like or spherical carrier, its functionality as a photocatalyst is relatively high. However, since it is a thin film, in a fluidized bed where the thin films rub against each other, there is a problem that the thin film is broken by peeling or colliding and its function is lost. However, since the functionality is exhibited only on the surface of the thin film, there is a problem that the functionality is insufficient in the absolute amount of the photocatalyst as compared with the powder.

Therefore, in this technical field, simultaneously possesses a powerful photocatalytic function by titanium dioxide formed as a thin film by a sol-gel method and the like, and a large amount of titanium dioxide in a powder mixture immobilized by an immobilization method, and There is a strong need for the development of new types of photocatalysts that combine the features of both methods, such that thin films do not peel even if they rub against each other, and do not lose their functionality even if they break by collision. It was. In such a situation, the inventors have found that the above-mentioned problems in the technical field can be effectively solved by adopting the following specific technical means in the process of intensive studies. The invention has been completed.

The present invention provides a new type of solid photocatalyst material composed of a solid material (no carrier) composed only of titanium dioxide having a photocatalytic function, a method for producing the same, and a water treatment apparatus using the solid photocatalyst material. It is the purpose.

Further, the present invention is composed of the same crystal from the outer shell to the inner core of the solid, and does not include a rutile type crystal, but only an anatase type crystal (may include a brookite type crystal). A solid photocatalyst material composed of a solid material comprising the following (i) to (vi);
(I) pore diameter (pore size) of 2 to 28 nm,
(Ii) specific surface area of 70 to 110 m ² / g,
(Iii) True density is 3.90 ± 1.0 g / cm ³ ,
(Iv) The bulk specific gravity is 1.3 to 1.6,
(V) Vickers hardness is 600 to 800 Hv,
(Vi) the crystal grain size is 10-25 nm,
It aims at providing the solid photocatalyst material which satisfy | fills these numerical values, and its manufacturing method.

The present invention for solving the above-described problems comprises the following technical means.
(1) A solid photocatalyst material comprising a solid material (without a carrier) composed only of titanium dioxide having a photocatalytic function,
Containing only titanium dioxide of anatase type crystal (may include brookite type crystal) without rutile type crystal, the following (i) to (vi):
(I) pore diameter (pore size) of 2 to 28 nm,
(Ii) specific surface area of 70 to 110 m ² / g,
(Iii) True density is 3.90 ± 1.0 g / cm ³ ,
(Iv) The bulk specific gravity is 1.3 to 1.6,
(V) Vickers hardness is 600 to 800 Hv,
(Vi) the crystal grain size is 10-25 nm,
Solid photocatalyst material characterized by satisfying each numerical value of
(2) The solid body comprising only titanium dioxide of the same anatase type crystal (may include brookite type crystal) from the outer shell to the inner core of the solid material as described in (1) above Solid photocatalyst material.
(3) Acetaldehyde can be decomposed and removed by 5.0 μmol / h or more by the JIS R1701-2 test method at normal temperature and pressure when irradiated with an actinic ray against the photocatalyst at an intensity of 0.8 mJ / cm ² sec. The solid photocatalyst material according to (1) or (2), which has photocatalytic activity.
(4) The solid photocatalyst material according to any one of (1) to (3), wherein the BET specific surface area by nitrogen adsorption has a specific surface area of 110 m ² / g.
(5) To a titanium dioxide colloidal gel dispersion prepared based on the sol-gel method, an organic solid nucleating material is added and mixed to prepare a highly viscous slurry, and then the moisture of the highly viscous slurry is Removing in an atmosphere at a temperature of 20 to 60 ° C. to prepare a wet gel, and baking the obtained wet gel at a temperature of 500 to 650 ° C. to prepare a solid having a flaky form; A method for producing a solid photocatalyst material, comprising using a floc-forming aggregate selected from activated carbon, cellulose, or polyvinyl alcohol as a nucleation material for organic solids.
(6) The method for producing a solid photocatalyst material according to the above (5), wherein the wet gel is baked to prepare a plate-like or amorphous flaky solid.
(7) The solid photocatalyst according to (6) above, wherein the flaky solid is washed with warm water, dried, and then classified to prepare a flaky photocatalyst having a plate shape or an amorphous shape. A method of manufacturing the material.
(8) A water treatment device for carrying out water purification using the solid photocatalyst material according to any one of (1) to (4) and light energy,
Connected by connecting a series of glass tubes filled with a fixed amount of photocatalyst solid flakes (flake catalyst), which is a solid photocatalyst material, in series, and connected in parallel to a predetermined number of rows A pipe device, means for exciting the photocatalyst filled in the glass tube by irradiating the glass tube with ultraviolet light, a tank for storing the water to be treated, a tank for storing the treated water, and the water to be treated A water treatment device comprising: a pump for passing water at a predetermined water flow rate through a pipe device.
(9) The apparatus according to (8), wherein the inner diameter (mmφ) of the glass tube is φ8-15.
(10) The apparatus according to (8), wherein the water flow rate is 50 ml / min to 5 L / min.
(11) The filling amount of the photocatalyst solid flakes as a fixed bed with respect to the glass tube is 10 g to 50 g in the tube inner diameter φ8 to φ13.5 (mmφ) when the filling length is 300 mm. Equipment.

Next, the present invention will be described in more detail.
Here, the solid photocatalyst material of the present invention will be described. The solid photocatalyst material of the present invention does not contain a rutile type crystal, but is composed only of titanium dioxide of anatase type crystal (which may contain a brookite type crystal). A solid photocatalyst material having a pore size of 2 to 28 nm, a specific surface area of 70 to 110 m ² / g, a true density of 3.90 ± 1.0 g / cm ³ , and a bulk specific gravity of 1 .3 to 1.6, a Vickers hardness of 600 to 800 Hv, and a crystal grain size of 10 to 25 nm.

The solid photocatalyst material of the present invention generally does not have a “support” component used in the photocatalyst, and the titanium dioxide photocatalyst material is composed of the same crystals from the outer shell to the inner core of the solid material constituting the solid photocatalyst material. It is a solid photocatalyst material made of a solid material that does not include a rutile crystal and is composed only of an anatase crystal (may include a brookite crystal). The solid photocatalyst material of the present invention has a high specific surface area of 70 to 110 m ² / g, and thus has an excellent adsorption function, and has a Vickers hardness of 600 to 800 Hv, a high hardness, and rubs against each other. Even if it has, it has the characteristic of having high durability which does not break.

The photocatalytic activity of the solid photocatalyst material of the present invention will be described. For example, an aldehyde dispersion test (based on the JIS R1701-2 test method) using the solid photocatalyst material of the present invention (flake catalyst; solid flake) is performed in order to examine its aldehyde resolution. The changes in acetaldehyde and CO ₂ concentrations when performed are shown in FIG. In the calculation formula shown in the figure, Qa = Ra × [A0] × f × 1.016 × 60 / (100 × 22.4)
In the formula, Qa is a numerical value to be obtained (μmol / h),
Ra is the acetaldehyde removal rate (%),
[A0] is the concentration of introduced gas,
f indicates a gas flow rate (= 1 L / min), respectively.

As a result of the calculation by the above formula, the amount of acetaldehyde removed by the solid photocatalyst material (flake catalyst) of the present invention was 7.55 μmol / h, which is 44 times higher than the certification standard value of the photocatalyst industry association. Indicates that it has activity.

Next, FIG. 2 shows the measurement result of the particle diameter of the titanium dioxide crystal constituting the solid photocatalyst material of the present invention by SEM observation. The figure shows that the crystal grain size can be read as 0.5 μm × 1/20 = 25 nm, even if there is a portion where the sharpness of the image is insufficient. Moreover, the measurement result of the particle diameter of the titanium dioxide crystal which comprises the solid photocatalyst material of this invention by an AFM atomic force microscope is shown in FIG. From this figure, the crystal grain size can be read as 200 nm × 1/20 = 10 nm.

Next, the measurement result of the specific surface area of the solid photocatalyst material of the present invention by nitrogen adsorption is shown in FIG. In the figure, the BET specific surface area is measured by Belsorb-max (manufactured by Microtracbell). Moreover, the external appearance of the solid photocatalyst material (flakes catalyst) of this invention is shown in FIG. Moreover, the analysis result of the crystal type by the X ray diffraction of the solid photocatalyst material of this invention is shown in FIG. From these figures, it can be clearly understood that the solid photocatalyst material of the present invention is composed of a solid material composed only of anatase type crystals having a purity of 95 to 98%. Here, in addition to the anatase type crystal, a brookite type crystal may be included.

As for the photocatalytic activity of the solid photocatalyst material of the present invention, when irradiated with actinic rays (ultraviolet rays) with respect to the photocatalyst, for example, at an intensity of 0.8 mJ / cm ² sec, at room temperature and normal pressure, for example, acetaldehyde, According to the JIS R1701-2 test method, it has a photocatalytic activity capable of decomposing and removing 5.0 μmol / h or more.

Next, the basic principle of the method for producing the solid photocatalyst material of the present invention will be described. First, in the method for producing a solid photocatalyst material of the present invention, a titanium dioxide colloidal dispersion sol is prepared by a method based on a general sol-gel method. In this case, only water is evaporated and fired until it is gelled. Then, the titanium dioxide colloidal dispersion gel is not solidified, but only becomes a titanium dioxide white powder.

In the process of advancing research, the present inventor, in the process of condensation polymerization of the wet gel from which water has been removed from the titanium dioxide colloidal dispersion sol, forms a tighter bonded state of the titanium dioxide crystals. The existence of a nucleation material serving as a nucleus is indispensable, and it has been found that it is effective to contain a nucleation material having an organic solid content that burns and disappears after firing. That is, as a requirement for the nucleation material of this organic solid content, the particle size is small so as not to lose the fluidity of the sol even after the nucleation material is added to and mixed with the titanium dioxide colloidal dispersion sol, The present inventors have found that a substance having a high affinity with water, for example, a floc-forming aggregate selected from activated carbon, cellulose and polyvinyl alcohol is effective. In the present invention, a substance that aggregates crystals to form a floc is referred to as a floc-forming aggregate.

By selecting these organic solid content nucleating materials, a high-viscosity slurry is formed from the titanium dioxide colloidal dispersion sol, and in the process of drying this, it becomes a nucleus in the high-viscosity slurry. Titanium dioxide crystals are gathered around to form a network structure between the crystals, so that the crystal-bonded molecules do not become titanium dioxide powder even after firing, and the mixing ratio of the constituent components is adjusted to form a network. It has been found that a structure is formed to cover the organic solids (see FIG. 7). When this is baked, the organic solid content serving as a nucleus burns, and a structure of titanium dioxide, which is an inorganic crystal, can be obtained as a residue (see FIG. 8).

Next, the embodiment of the production process of the solid photocatalyst material of the present invention will be described in detail. In the production method of the solid photocatalyst material of the present invention, first, titanium dioxide colloidal dispersion is performed based on a general sol-gel method. Prepare the solution. In this case, for example, a titanium isopropoxide solution is dropped and mixed in pure water, then dispersed with an acid such as concentrated nitric acid, and concentrated to prepare a titanium dioxide colloidal dispersion.

Next, the resulting titanium dioxide colloidal dispersion is mixed with high-viscosity, for example, by adding and mixing floc-forming aggregates such as activated carbon of organic solids that disappears upon burning, cellulose, and polyvinyl alcohol as nucleation materials. A slurry is prepared. In this case, the nucleation material may be any material as long as it can prepare a highly viscous slurry equivalent to the highly viscous slurry from the titanium dioxide colloidal dispersion, and is not limited to the activated carbon, cellulose, or polyvinyl alcohol. Can be used in the same manner as long as they have the same effect. Next, the moisture of the highly viscous slurry is removed in an atmosphere at a temperature of 20 to 60 ° C., for example, at a temperature of 20 to 50 ° C. to prepare a wet gel such as a black wet gel.

Next, a wet gel such as this black wet gel is baked at 600 ° C. for 1 hour, for example. Thereby, a solid material in the form of flakes of various sizes such as milky white is prepared. Next, the obtained flake-shaped solid material is washed with, for example, hot water of 80 to 100 ° C. and dried to prepare a flake catalyst, which is classified to adjust the particle size, thereby completing the photocatalyst. A solid photocatalyst material is prepared as a product. The solid photocatalyst material obtained by the above process is characterized in that its form is a plate-like or amorphous shape, and it consists of a solid material composed only of anatase-type crystal titanium dioxide having a purity of 95 to 98%. In this case, a brookite type crystal may be included in addition to the anatase type crystal.

Next, the usefulness of the solid photocatalyst material of the present invention will be described. As is clear from the characteristic data of the above-described solid photocatalyst material (flake catalyst; solid flake) of the present invention, the solid photocatalyst material of the present invention is used for environmental purification such as water and air in response to ultraviolet rays, for example. It has a high level of photocatalytic ability. Therefore, it is possible to use the photocatalyst function widely as a solid photocatalyst material for various photocatalyst products that are generally known or not known as photocatalyst products.

Moreover, since the solid photocatalyst material of the present invention does not require the use of a carrier for supporting the titanium dioxide photocatalyst inevitably used in known titanium dioxide photocatalysts, its production facility, production process or The production system has an advantage that it is simpler than existing photocatalysts. Moreover, since the solid photocatalyst material of the present invention has excellent durability as a solid material composed only of titanium dioxide of anatase type crystal (may contain brookite type crystal), it is used in water. In particular, it can be used stably even in long-term underwater use, and can be used not only in the air layer, but also in fixed beds and fluidized beds that are required for underwater use. And it has the characteristics that the solid photocatalyst material after using it for the purification process of water is easy to reproduce | regenerate and reuse.

As a specific application area of the solid photocatalyst material of the present invention having such characteristics, for example, in regions such as developing countries where water used for drinking water depends on the water of rivers and ponds, the water is used. It is useful as a basic technology for constructing a simple water purification system that can be supplied as safe drinking water that is purified by utilizing the antibacterial action of the photocatalyst and prevents germs from breeding. is there.

In constructing such a simple water purification system, the solid photocatalyst material of the present invention does not require a step of supporting the photocatalyst on a carrier and the material thereof, so that the number of parts and the manufacturing process are reduced. It is advantageous in terms of cost, and in particular, has an exceptional feature that existing photocatalysts do not have, such as superiority in production and use in the original land, such as in developing countries. From this, the present invention is particularly effective for the antibacterial action by a simple photocatalyst for effectively solving the problems of depletion of water resources and lack of safe drinking water accompanying the global warming and the expansion of desert areas. It is useful as a new technology that makes it possible to construct a purification system using the

The following effects are exhibited by the present invention.
(1) It is possible to provide a new type of solid photocatalyst material composed of a solid material (no carrier) composed only of titanium dioxide having a photocatalytic function.
(2) A solid consisting of a solid material composed only of titanium dioxide by the same anatase type crystal (may include a brookite type crystal) without including a rutile type crystal from the outer shell to the inner core of the solid. A photocatalytic material can be provided.
(3) The amount of acetaldehyde removed by the solid photocatalyst material (photocatalyst solid flake; flake catalyst) of the present invention is 7.55 μmol / h, which is 44 times higher than the certified standard value of the photocatalyst industry association.
(4) The solid photocatalyst material (photocatalyst solid flake; flake catalyst) of the present invention uses a titanium dioxide colloidal dispersion prepared based on the sol-gel method, and uses a simple system without installing a special facility. Can be manufactured and used.
(5) According to the present invention, antibacterial activity using a photocatalyst in a developing system such as a developing country where drinking water depends on water such as rivers and ponds under irradiation of sunlight. It is possible to prepare and provide safe drinking water that is purified by the action and does not propagate various germs.
(6) The solid photocatalyst material after being used for water purification treatment can be easily regenerated and reused by a simple operation (such as incineration treatment).
(7) It is possible to provide a water treatment device that performs water purification using the solid photocatalyst material of the present invention and light energy.

As a result of conducting an acetaldehyde decomposition test (according to JIS R1701-2 test method) using the solid photocatalyst material (photocatalyst solid flake; flake catalyst) of the present invention, changes in the acetaldehyde and CO ₂ concentration obtained are shown. In the calculation formula shown in the figure, Qa = Ra × [A0] × f × 1.016 × 60 / (100 × 22.4), where Qa is a numerical value (μmol / h) to be obtained, and Ra is , Acetaldehyde removal rate (%), [A0] indicates the introduced gas concentration, and f indicates the gas flow rate (= 1 L / min). As a result of the calculation by the above calculation formula, the aldehyde removal amount by the flake catalyst (solid photocatalyst material) was 7.55 μmol / h, which is 44 times higher than the certification standard value of the photocatalyst industry association. Indicates that The measurement result of the titanium dioxide crystal particle diameter by SEM observation is shown. The figure can be read as crystal grain size: 0.5 μm × 1/20 = 25 nm even if there is a portion where the image definition is insufficient. The measurement result of the titanium dioxide crystal particle diameter by an AFM atomic force microscope is shown. From the figure, it can be read that the crystal grain size is 200 nm × 1/20 = 10 nm. The measurement result of the specific surface area of a flake catalyst by nitrogen adsorption is shown. The BET specific surface area was measured by Belsorb-max (manufactured by Microtracbell). The appearance of the flake catalyst is shown. The analysis result of the crystal form of the flake catalyst by X-ray diffraction is shown. From the results of the figure, it can be clearly understood that this product is composed only of anatase type crystals (may contain brookite type crystals). The figure which showed typically the tight binding state of the titanium dioxide crystal | crystallization formed in the process in which the wet gel which made water | moisture_content dissociated from the titanium dioxide colloidal dispersion sol condenses is shown. Left figure: appearance of wet gel before firing (swelling of organic solids is observed) and right figure: appearance of titanium dioxide structure after firing (holes with burned organic solids are observed) Show. The distribution of the pore diameter of the titanium dioxide crystal is shown. Measured by Belsorb-max (manufactured by Microtracbell). As shown in the figure, it was found that the pore diameter (pore size) has a distribution from 2 nm to 28 nm with the maximum being around 10 nm. An experimental example (closed circulation photocatalytic reaction device and experimental results) on the processing function of the solid photocatalyst material will be shown. From the circulation experiment on the processing function of the flake catalyst shown in the figure, the flake catalyst proved to withstand repeated use. The result (by JIS R1704 test method) of the photocatalyst water treatment function test by a solid photocatalyst material is shown. Left side: The concentration of metasulfonic acid (MSA) produced by photocatalytic oxidation of dimethyl sulfoxide (DMSO), and the right side: the concentration of DMSO. The test apparatus (plan view) used in the photocatalyst water treatment function test is shown. The test apparatus (front view) used in the photocatalyst water treatment function test is shown. The relationship between the tube inner diameter (tube diameter) of the glass tube (filled tube) filled with the flake catalyst and the reaction rate is shown. The relationship between the tube inner diameter (tube diameter) of the glass tube (filled tube) filled with the flake catalyst and the catalyst weight is shown. It is a schematic diagram of the water treatment equipment of the present invention. The mechanism of the demo device is shown. The photograph (whole) of the water treatment apparatus of this invention is shown. The photograph (part) of the water treatment apparatus of this invention is shown. The photocatalyst water treatment experimental apparatus is shown.

Next, the present invention will be specifically described with reference to examples and test examples. However, the present invention is not limited to the following examples and test examples.

First, in order to obtain a colloidal dispersion of titanium dioxide, a titanium dioxide colloidal dispersion was prepared based on a general sol-gel method. The colloidal dispersion was prepared by the following method, for example, in the same manner as described in the literature [= Sakuo Sakuhana: Science of Sol-Gel Method]. That is, 300 g of titanium isopropoxide 95% solution was dropped and mixed in 1,600 g of pure water at 80 ° C., and then dispersed with 13 g of concentrated nitric acid, and the dispersion was concentrated to form 600 g of the formed colloidal dispersion. Got.

60 g of activated carbon (manufactured by Futaba Chemical) as a nucleation material is added to and mixed with 600 g of the titanium dioxide colloidal dispersion obtained in this manner to prepare a highly viscous slurry. Removal under an atmosphere of 50 ° C. yielded 100 g of a black wet gel.

This black wet gel was baked at 600 ° C. for 1 hour to obtain 30 g of a solid material having milky white and various flaky shapes. Since the titanium dioxide colloidal dispersion itself is strongly acidic, the obtained flaky solid material was washed with hot water at 80 to 100 ° C. and dried to prepare a solid photocatalyst material (flake catalyst). Subsequently, this was classified and adjusted to a predetermined particle size to obtain a solid photocatalyst material (flake catalyst) as a photocatalyst product as a finished product.

The solid photocatalyst material (flake catalyst) thus obtained is a plate or irregular shape having a size of 2 to 5 mm and a thickness of 0.5 to 1.2 mm, a Vickers hardness of 700 Hv, and a pencil scratch hardness of It is a solid solid of 9H, the composition of which is anatase type titanium dioxide with a purity of 95 to 98%, and a solid having a primary crystal grain size of 10 to 20 nm bonded and solidified. This was confirmed by observation by X-ray diffraction and AFM imaging. In this case, it was observed that a brookite type crystal was included in addition to the anatase type crystal.

Although the obtained solid photocatalyst material is a solid substance, its BET specific surface area is 110 m ² / g, and it is observed by BET that it is almost equivalent to powdered titanium dioxide P25 (manufactured by Evonik, Germany). It was done.

In the same manner as in Example 1, a titanium dioxide colloidal dispersion was prepared as follows. That is, 300 g of a titanium tetraisopropoxide 95% solution was dropped and mixed in 1,600 g of pure water at 80 ° C., then dispersed with 13 g of concentrated nitric acid and concentrated to obtain 600 g of the formed colloidal solution.

60 g of activated carbon (manufactured by Futaba Chemical) as a nucleation material is added to and mixed with 600 g of the titanium dioxide colloidal dispersion obtained in this manner to prepare a highly viscous slurry. Removal under an atmosphere of 50 ° C. gave 100 g of a black wet gel.

This black wet gel was baked at 600 ° C. for 1 hour to obtain 30 g of a flaky photocatalyst solid material (flake catalyst) that was milky white and varied in size. Since the titanium dioxide colloidal liquid itself is strongly acidic, the obtained flakes are washed with hot water at 80 to 100 ° C. and dried to complete the flake catalyst, and then classified and adjusted to a predetermined particle size. A solid photocatalyst material (flake catalyst) as a photocatalyst product was obtained as a finished product.

The solid photocatalyst material (flake catalyst) thus obtained has a plate shape or irregular shape with a size of 2 to 5 mm and a thickness of 0.5 to 1.2 mm, a Vickers hardness of 700 Hv, and a pencil scratch hardness. Is a hard solid of 9H, and its composition is anatase type titanium dioxide with a purity of 95 to 98%, which is solidified by combining crystals with a primary crystal grain size of 10 to 20 nm. It was confirmed by observation by X-ray diffraction and AFM imaging. In this case, it was observed that a brookite type crystal was included in addition to the anatase type crystal.

Although the obtained solid photocatalyst material (flake catalyst) is a solid substance, its BET specific surface area is 110 m ² / g, which is almost the same as powder titanium dioxide P25 (manufactured by Evonik, Germany). It was observed with BET.

In the same manner as in Example 1, a titanium dioxide crystal-dispersed sol was prepared as follows. That is, 500 g of a titanium ethoxide 95% solution was dropped and mixed in 1,800 g of pure water at 80 ° C., then dispersed with 18 g of hydrochloric acid and concentrated to obtain 800 g of the formed colloidal solution.

To 800 g of the titanium dioxide colloidal dispersion thus obtained, 80 g of artificial cellulose “Theolas TG101” (manufactured by Asahi Kasei Chemical) is added and mixed as a nucleation material to prepare a highly viscous slurry. Was removed at a temperature of 20 to 50 ° C. to obtain 150 g of a white wet gel.

This white wet gel was baked at 600 ° C. for 1 hour to obtain 50 g of a solid material having a milky white shape and various flaky shapes. Since the titanium dioxide colloidal liquid itself is strongly acidic, the obtained flakes are washed with hot water at 80 to 100 ° C. and dried to complete a solid photocatalyst material (flake catalyst), and then classified, By adjusting the particle size, a solid photocatalyst material (flake catalyst) as a photocatalyst product was obtained as a finished product.

In the same manner as in Example 1, a titanium dioxide crystal-dispersed sol was prepared as follows. That is, 400 g of titanium isopropoxide 95% solution was dropped and mixed in 1,700 g of pure water at 80 ° C., then dispersed with 32 g of 1N sodium hydroxide and concentrated to obtain 700 g of the formed colloidal solution. It was.

To 700 g of the titanium dioxide colloidal dispersion thus obtained, 75 g of polyvinyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) as a nucleating material is added and mixed to prepare a highly viscous slurry. Removal under an atmosphere of ˜50 ° C. yielded 160 g of a white wet gel.

This white wet gel was baked at 600 ° C. for 1 hour to obtain 40 g of a solid material having a milky white shape and various flaky shapes. Since the titanium dioxide colloidal liquid itself is strongly acidic, the obtained flakes are washed with hot water at 80 to 100 ° C. and dried to complete the flake catalyst, and then classified and adjusted to a predetermined particle size. A solid photocatalyst material (flake catalyst) as a photocatalyst product was obtained as a finished product.

Next, the present invention will be specifically described based on test examples.
[Test example]
(1) Acetaldehyde dispersion test Using a solid photocatalyst material (photocatalyst solid flake; flake catalyst), an acetaldehyde dispersion test (according to JIS R1701-2 test) was conducted to examine changes in acetaldehyde and CO ₂ concentration.

Figure 1 shows the results. In the calculation formula shown in the figure, Qa = Ra × [A0] × f × 1.016 × 60 / (100 × 22.4), Qa is a numerical value to be obtained (μmol / h), and Ra is acetaldehyde removal. The rate (%) and [A0] indicate the concentration of the introduced gas, and f indicates the gas flow rate (= 1 L / min), respectively.

As a result of calculation by the above formula, the amount of acetaldehyde removed by the flake catalyst was 7.55 μmol / h. This value indicates that the activity is 44 times higher than the certification standard value of the Photocatalyst Industry Association.

(2) Revision of titanium dioxide crystal particle diameter by SEM observation The particle diameter of the titanium dioxide crystal constituting the flake catalyst was examined by SEM observation. FIG. 2 shows the result. In the figure, the crystal grain size can be read as 0.5 μm × 1/20 = 25 nm even if there is a portion where the image definition is not sufficient.

(3) Measurement of Titanium Dioxide Crystal Particle Diameter with AFM Atomic Force Microscope The particle diameter of the titanium dioxide crystal constituting the flake catalyst was examined with an AFM atomic force microscope. FIG. 3 shows the result. From the figure, the crystal grain size can be read as 200 nm × 1/20 = 10 nm.

(4) Measurement of BET specific surface area by nitrogen adsorption The BET specific surface area of the titanium dioxide crystal constituting the flake catalyst was examined by a nitrogen adsorption method. At that time, the BET specific surface area was measured using Belsorb-max (manufactured by Microtracbell). FIG. 4 shows the result. The BET specific surface area is observed to be 110 m ² / g.

(5) Appearance of flake catalyst The form of the flake catalyst was measured. FIG. 5 shows the appearance of the flake catalyst. From the figure, it is observed that the flake catalyst is a plate-like or irregular-shaped figure having a size of 2 to 5 mm and a thickness of 0.5 to 1.2 mm.

(6) Analysis of crystal form by X-ray diffraction The crystal form of the titanium dioxide crystal forming the flake catalyst was analyzed by X-ray diffraction. FIG. 6 shows the result. From the figure, it is clearly observed that the flake catalyst (PSF-01) is composed only of titanium dioxide of anatase type crystal (including brookite type crystal) having a purity of 95 to 98%.

(7) Appearance of the wet gel before and after firing In the process of producing the flake catalyst, an organic pigment serving as a nucleus for forming a tighter bonded state of the titanium dioxide crystals is added and mixed. The appearance of the wet gel before firing from which moisture of the viscous slurry was removed and the appearance after burning and disappearing of the organic pigment after firing this were examined.

Figure 8 shows the results. In the figure, the left shows the appearance before firing (having the swelling of the organic pigment), and the right shows the appearance after firing (having the pores where the organic pigment burned).

(8) Measurement of pore diameter (pore size) The pore diameter of the titanium dioxide crystal constituting the flake catalyst was examined. At that time, the pore diameter (BJH pore size) was measured using Belsorb-max (manufactured by Microtracbell). FIG. 9 shows the result. From the figure, it was shown that the pore diameter (pore size) was most frequently around 10 nm and distributed in the range of 2 nm to 28 nm.

(9) Circulation experiment on processing function of flake catalyst The tolerance of the photocatalytic function when the flake catalyst was repeatedly used was examined. At that time, a dimethyl sulfoxide (DMSO) aqueous solution is circulated through a flake catalyst spread over a range of approximately 100 × 100 mm, the DMSO concentration at the outlet and the inlet, and the concentration of methanesulfonic acid (MSA) generated by photocatalytic oxidation of DMSO. Was detected and measured by a gas chromatograph. FIG. 10 shows the reaction rate of formic acid (1 × 10 ⁻³ mol / L) by repeating the closed-circulation photocatalytic reaction apparatus (photocatalytic reactor) used in this circulation experiment and the photocatalytic reaction (8 hours) in water, The result (14 times) which measured the density | concentration by the ion chromatography fluff once for every time formic acid as a sample is shown.

In the figure, the experimental conditions are as follows: experimental solution volume: 500 mL (Sampling bottom 500 mL), formic acid concentration: 1 × 10 ⁻³ mol / L, UV intensity: 2.0 mW / cm ² , catalyst amount used: 24 g / 50 cm catalyst tube, Catalyst pipe standard: Pyrex (registered trademark) pipe (outer diameter 12 mm, t = 1 mm) 500 mm, circulation flow rate: 50 mL / min. From the concentration change over time shown in the figure, it is confirmed that the flake catalyst (PSF-01) oxidatively decomposes dimethyl sulfoxide (DMSO) in water. From the figure, it was proved that the flake catalyst can withstand repeated use.

(10) Water treatment function test The water treatment function by the flake catalyst was examined by a photocatalyst water treatment function test (JIS R1704 test method). FIG. 11 shows the results of detecting and measuring the concentrations of dimethyl sulfoxide (DMSO) and methane sulfoxide (MSA) using a gas chromatograph. In the figure, the concentration of methanesulfonic acid (MSA) produced by photocatalytic oxidation of dimethyl sulfoxide (DMSO) is shown on the left side, and the concentration of DMSO is shown on the right side.

12 and 13 are a plan view and a front view of a test apparatus used in the photocatalytic water treatment function test, respectively. Means in the figure are Lamp: ultraviolet irradiation lamp, Pump: pump, Piece: test piece (flakes catalyst), Test solution: test solution, Turbent Piece: weir , Photocatalyst: flake catalyst.

Next, the water treatment apparatus which performs the purification process of water using the solid photocatalyst material of this invention and light energy is demonstrated.
1. Outline of the apparatus The water treatment apparatus of the present invention performs purification treatment by photocatalytic oxidation of water to be treated, using the photocatalytic solid flakes (flake catalyst) which is the solid photocatalyst material of the present invention.
Examples of the usage include photocatalyst sterilization of drinking water and advanced treatment of agricultural underground wastewater. In the present invention, one row of paths in which glass tubes filled with photocatalyst solid flakes (flake catalyst), which is the solid photocatalyst material of the present invention, as a fixed bed are connected in series, are further arranged in parallel with two rows, three rows, and so on. Water to be treated is passed through a connecting pipe device formed by connecting to the water. The glass tube of this connecting tube device is irradiated with sunlight or ultraviolet rays from an ultraviolet lamp to excite the solid photocatalyst material filled as a fixed bed in the glass tube and contained in the water to be treated. It is possible to obtain purified water by oxidizing and decomposing organic matter with a solid photocatalyst material. FIG. 16 shows an outline of the water treatment apparatus.

2. Glass tube and tube inner diameter (mmφ)
As the glass tube, for example, quartz glass or borosilicate glass is preferably used. Regarding the filling amount and reaction rate of the photocatalyst solid flakes (flake catalyst) of the present invention with respect to the glass tube, the reaction rate is improved in proportion to the inner diameter of the glass tube through which water to be treated is passed. When the tube inner diameter (mmφ) exceeds φ15, the reaction rate decreases. FIG. 14 shows the relationship between the tube inner diameter (tube diameter) (mmφ) of the glass tube and the reaction rate. As shown in this figure, the inner diameter of the glass tube to be applied is in the range of φ8 to 15 (mmφ), and preferably in the range of 8 to 13.5 (mmφ).

3. Water flow rate Since the reaction rate of the photocatalyst is slow, the longer the contact time of the water to be treated with the photocatalyst solid flakes (flake catalyst), the more the water flow rate can be used. / Min. In the water treatment apparatus of the present invention, as a result of conducting the purification test, the available water flow rate range was 50 ml / min to 5 L / min in consideration of securing the flow rate.

4). Filling amount of photocatalyst solid flake (flake catalyst) Since the shape of the photocatalyst solid flake is a flake shape, it cannot be closely packed, and inevitably generates voids. For this reason, the flow path resistance at the time of passing water to be treated is reduced as compared with the case of a spherical shape that is densely packed. As a result, when the filling length of the photocatalyst solid flake is 300 mm, the glass tube has a tube inner diameter φ8 of 10 g, the glass tube has a tube inner diameter φ12 of 25 g, and the glass tube has a tube inner diameter φ13.5 of From the actual value of 50 g and the measured value of the photocatalytic action of the photocatalytic solid flakes, a filling amount of 30 to 170 g / m is desirable. FIG. 15 shows the relationship between the filling amount of the photocatalyst solid flakes on which the actual values are plotted and the tube inner diameter (tube diameter) of the glass tube.

Next, an embodiment of a water treatment device for purifying water will be described.

In this example, dirty water (untreated water) containing blue ink was decomposed with light energy using photocatalyst solid flakes (flake catalyst), and converted into purified and clean water (treated water). . As a result of passing water at a flow rate of about 1 liter per hour with a pump, a blue ink was formed through a connecting pipe device formed by connecting 10 rows of glass tubes filled with the photocatalytic solid flakes of the present invention as a fixed bed in parallel. Water (treated water) that was purified by decomposition and purified was obtained. In FIG. 16, the aspect of the water treatment apparatus used by the present Example is shown. Similarly, it was confirmed that drinking water contaminated with bacteria and chemicals can be purified to a safe level. FIGS. 17 to 19 show a water treatment experimental device, a mechanism of a demonstration device, and a photographic drawing of the device for carrying out water purification treatment with photocatalytic solid flakes, respectively.

An embodiment of a photocatalytic water treatment device for carrying out water purification treatment is shown. A connecting pipe device was configured by connecting in parallel a single line of paths in which glass tubes filled with photocatalytic solid flakes as a fixed bed were connected in series. A 20 W black light was placed on this, and two 10 L large transparent round bottles were connected to construct a water treatment apparatus in the present invention. In FIG. 20, the schematic diagram of a photocatalyst water treatment experimental apparatus is shown.

As described above in detail, the present invention relates to a solid photocatalyst material composed of a solid material composed only of titanium dioxide having a photocatalytic function, a manufacturing method thereof, and a water treatment apparatus using the solid photocatalyst material and light energy. According to the present invention, it is possible to provide a new type of solid photocatalyst comprising 1) a solid (without a carrier) formed only from titanium dioxide having a photocatalytic function, and 2) from the outer shell of the solid It is possible to provide a solid photocatalyst material composed of a solid material composed only of titanium dioxide of the same anatase type crystal (may include a brookite type crystal) without including a rutile type crystal to the core 3) The amount of acetaldehyde removed by the solid photocatalyst material (flake catalyst) of the present invention is 7.55 μmol / h, which is 44 times the certified standard value of the photocatalyst industry association. 4) The solid photocatalyst material (flake catalyst) of the present invention uses a titanium dioxide colloidal dispersion prepared based on the sol-gel method, and is safe with a simple system without installing a special facility. 5) According to the present invention, in a region where water is dependent on water such as rivers and ponds, such as in developing countries, sunlight can be used. The water can be purified by using the antibacterial action of the photocatalyst under irradiation of water, etc., and safe drinking water can be prepared and provided so that no germs can propagate. 6) Used for water purification treatment The solid photocatalyst material can be easily regenerated and reused by a simple operation (such as incineration). 7) The solid photocatalyst of the present invention can be expected. Using materials and light energy A water treatment device for purifying water can be provided.

Claims

It is a solid photocatalyst material composed of a solid material (without a carrier) composed only of titanium dioxide having a photocatalytic function,
Containing only titanium dioxide of anatase type crystal (may include brookite type crystal) without rutile type crystal, the following (i) to (vi):
(I) pore diameter (pore size) of 2 to 28 nm,
(Ii) specific surface area of 70 to 110 m 2 / g,
(Iii) True density is 3.90 ± 1.0 g / cm 3 ,
(Iv) The bulk specific gravity is 1.3 to 1.6,
(V) Vickers hardness is 600 to 800 Hv,
(Vi) the crystal grain size is 10-25 nm,
Solid photocatalyst material characterized by satisfying each numerical value of
The solid photocatalyst material according to claim 1, wherein the solid photocatalyst material is composed of only solid titanium dioxide of the same anatase type crystal (may contain brookite type crystal) from the outer shell to the inner core of the solid.
Photocatalytic activity that acetaldehyde can be decomposed and removed by 5.0 μmol / h or more by the JISR1701-2 test method at normal temperature and normal pressure when irradiated with an actinic ray against the photocatalyst at an intensity of 0.8 mJ / cm 2 sec. The solid photocatalyst material according to claim 1 or 2, comprising:
The solid photocatalyst material in any one of Claim 1 to 3 with which the BET specific surface area by nitrogen adsorption | suction has a specific surface area of 110 m < 2 > / g.
A nucleating material containing an organic solid is added to and mixed with a titanium dioxide colloidal gel dispersion prepared based on the sol-gel method to prepare a highly viscous slurry. Removing in an atmosphere of 60 ° C. to prepare a wet gel, and baking the obtained wet gel at a temperature of 500 to 650 ° C. to prepare a solid having a flaky form; A floc-forming aggregate selected from activated carbon, cellulose, or polyvinyl alcohol is used as a nucleating material for the solid photocatalyst material.
6. The method for producing a solid photocatalyst material according to claim 5, wherein the wet gel is baked to prepare a plate-like or amorphous flaky solid.
The method for producing a solid photocatalyst material according to claim 6, wherein the flaky solid is washed with warm water, dried, and then classified to adjust the particle size to prepare a plate-like or amorphous flake photocatalyst. .
A water treatment device for carrying out water purification treatment using the solid photocatalyst material according to any one of claims 1 to 4 and light energy,
Connected by connecting a series of glass tubes filled with a fixed amount of photocatalyst solid flakes (flake catalyst), which is a solid photocatalyst material, in series, and connected in parallel to a predetermined number of rows A pipe device, means for exciting the photocatalyst filled in the glass tube by irradiating the glass tube with ultraviolet light, a tank for storing the water to be treated, a tank for storing the treated water, and the water to be treated A water treatment device comprising: a pump for passing water at a predetermined water flow rate through a pipe device.
The apparatus according to claim 8, wherein the inner diameter (mmφ) of the glass tube is φ8-15.
The apparatus according to claim 8, wherein the water flow rate is 50 ml / min to 5 L / min.
The apparatus according to claim 8, wherein a filling amount of the photocatalyst solid flake to the glass tube as a fixed bed is 10 g to 50 g in a tube inner diameter φ8 to φ13.5 (mmφ) when the filling length is 300 mm.