JP2000218170A - Production of titania fiber for photocatalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem with the fixing of photocatalytic particles and there by obtain titania fiber for photocatalyst with high photocatalytic activity and tensile strength by making the titania fiber with a BET surface area equivalent to a specific value or lower bear titanium oxide. SOLUTION: When titania fiber is used as a fiber made to bear titanium oxide, the adhesive properties between the fiber and the titanium oxide to be borne on the fiber are upgraded so that it is possible to prevent the titanium oxide from being stripped off the fiber during using a photocatalyst. In this case, the BET surface area of the titania fiber is set at 0.5 m2/g or less. When the titania fiber is produced, the process to be used is, for example, a sol-gel process to spin a liquid containing polytitanoxane and bake the filament or a process to spin a liquid containing the polytitanoxane and a silicon compound and bake the filament. The bearing ratio of the titanium oxide varies depending upon the monofilament diameter or the like of the titania fiber. However, it is preferable to normally set the ratio at about 10-50 wt.%, especially about 15-30 wt.% of the titanium oxide to the amount used of the titania fiber for photocatalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a titania fiber for photocatalyst. Specifically, decomposition and removal of NOx and odorous substances,
The present invention relates to a method for producing titania fiber for photocatalyst having high photocatalytic activity and tensile strength, which is used for purification of air and water, such as purification of contaminated rivers and lakes, decolorization of dyed wastewater, and water treatment.

[0002]

2. Description of the Related Art It is known that when a semiconductor is irradiated with light of a specific wavelength, electrons having a strong reducing action and holes having a strong oxidizing action are generated. ) Is known. By utilizing such photocatalysis, NOx in the atmosphere is decomposed, odorous substances in living and working spaces,
Decomposition and removal of harmful substances and molds, and treatment of harmful substances such as decomposition and removal of environmental pollutants such as organic solvents, pesticides, and surfactants in water are being studied.

As a substance having such a photocatalytic action, attention has been paid to titania (titanium oxide). However, conventionally available titania is a particle, and thus when applied to the above-described decomposition and removal, there is a problem that titanium oxide particles scatter and flow.

[0004] In order to prevent scattering and outflow of the titania particles, a method of immobilizing the titania particles on a sufficiently large substrate, for example, a method of laminating and pressing a mixture of the titania particles and a fluorine-based polymer (Japanese Unexamined Patent Publication No. No. 2,848,851), a method of thermally fusing titania particles to a fluorine-based polymer (Japanese Patent Application Laid-Open No. 4-334552), and a method of using a hardly decomposable binder as an adhesive on a base material (Japanese Patent Application Laid-Open No. 7-17).
No. 1408), a method in which a titania sol is coated on a substrate and then heat-treated to form a titania thin film on the substrate (Japanese Patent Application Laid-Open No. Hei 7-100378), and a method in which a woven fabric made of glass fiber is coated with titania ( JP-A-6-320010) has been proposed.

[0005] However, the above-mentioned Japanese Patent Application Laid-Open No. Hei 4-2848.
No. 51, JP-A-4-334552 and JP-A-7
The method described in JP-A-171408 is a special method of bonding, and the titania photocatalyst obtained by the method described in JP-A-7-100378 and JP-A-6-320010 is used for decomposition and removal. When applied, the adhesive and the base material are deteriorated, and there is a problem that titanium oxide falls off and scatters and flows out, and its application has been limited.

[0006] The present inventors aimed at preventing titanium oxide from falling off when applied to decomposition removal, etc. before.
Titania fibers which themselves have a photocatalytic function
No. -276705). However, for practical use, development of titania fibers having high tensile strength in addition to the above has been desired.

[0007]

The problem to be solved by the present invention is that NO
As for the photocatalytic titania fiber, which can be used for air and water purification, such as x, odorous substances, removal of harmful substances, purification of polluted rivers and lakes, decolorization of dyeing wastewater, wastewater treatment, water treatment, etc. An object of the present invention is to provide a photocatalytic titania fiber having high photocatalytic activity and high tensile strength without problems associated with immobilization of such photocatalytic particles.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that titanium oxide is supported on a specific inorganic fiber so that the titanium oxide does not fall off during use and a high photocatalyst can be obtained. The present inventors have found titania fibers for photocatalyst having activity and tensile strength and completed the present invention.

That is, according to the present invention, the BET surface area is 0.5 m
An object of the present invention is to provide a method for producing titania fiber for photocatalyst, wherein titanium oxide is supported on titania fiber of ² / g or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention is characterized in that titania fibers carry titanium oxide. By using titania fiber as the fiber for supporting titanium oxide, the adhesion and adhesion between the fiber and the titanium oxide supported on the fiber are improved, and the titanium oxide is prevented from falling off the fiber during use. it can. When titanium oxide is carried on glass fibers other than titania fibers, the adhesion and adhesion between the glass fibers and titanium oxide are poor, and the titanium oxide falls off during use. The titania fiber has a BET surface area of 0.5 m ² / g.
It is as follows. When the BET surface area is larger than 0.5 m ² / g, it is difficult to obtain the titania fiber for photocatalyst having high tensile strength of the present invention, although the reason is not clear.
The titania fiber usually has a single fiber diameter of about 5 μm or more.
About 100 μm, and the fiber length is 50 cm or more.

As a method for producing the titania fiber used in the present invention, for example, a method of spinning a liquid containing polytitanoxane and firing it (for example, JP-A-49-124336), a sol-gel method (for example, JP-A-62 -22332
No. 3) and a method of spinning and firing a liquid containing polytitanoxane and a silicon compound, and preferably a method of spinning and firing a liquid containing polytitanoxane and a silicon compound.

A specific example of a method for producing titania fiber in which a liquid containing polytitanoxane is spun and fired is described in (1)
Water is added to a solution in which titanium alkoxide is dissolved in a solvent to carry out a hydrolysis reaction and a polymerization reaction to form a polymer in the solution. (2) The polymer is dissolved in an organic solvent in which the polymer is soluble. Dissolving to obtain a spinning solution, (3) spinning the spinning solution to obtain a precursor fiber, and (4) firing the precursor fiber.

In the step (1) of the production method, a hydrolysis reaction and a polymerization reaction are carried out by adding water to a solution obtained by dissolving a titanium alkoxide in a solvent (hereinafter referred to as a titanium alkoxide solution). This is a step of producing a polymer. The titanium alkoxide has the general formula [1] Ti
(OR ₁ ) ₄ (wherein, R ₁ represents an alkyl group having 1 to 4 carbon atoms). More specifically, titanium tetramethoxide, titanium tetraethoxide, titanium tetra n-propoxide, titanium tetra iso-propoxide, titanium tetra n-butoxide, titanium tetra sec
-Butoxide, titanium tetratert-butoxide and the like, among which titanium tetraiso-propoxide in which R ₁ is an isopropyl group. The solvent is
Any substance that dissolves titanium alkoxide may be used, and examples thereof include alcohols, ethers, and aromatic hydrocarbons. The alcohol is represented by the general formula [2] R ₂ OH (where R ₂ represents an alkyl group having 1 to 4 carbon atoms), and specific examples include ethanol and isopropyl alcohol. No. Specific examples of ethers include tetrahydrofuran, diethyl ether and the like.
The amount of the solvent based on the titanium alkoxide is generally in the range of about 0.5 mol to about 50 mol per 1 mol of the titanium alkoxide. The water is preferably the same solvent as that in which the titanium alkoxide is dissolved, and diluted to a water concentration of about 1 to about 50% by weight. Water concentration 50% by weight
If the water content exceeding 1% is directly added to the titanium alkoxide solution, the reaction locally proceeds, and a polymer insoluble in the spinning solution may be precipitated during spinning in a later step. The amount of water added is usually in the range of about 1.5 mol to about 4 mol per 1 mol of titanium alkoxide.

In performing the step (1) of the production method, a titanium alkoxide is dissolved in a solvent and refluxed under an inert atmosphere such as a nitrogen atmosphere to prepare a titanium alkoxide solution. By adding water to the titanium alkoxide solution, a hydrolysis reaction and a polymerization reaction are performed to generate a polymer in the solution. When performing the step (1) of the production method, a compound having active hydrogen may be added to the titanium alkoxide solution. By adding an appropriate amount of a compound having active hydrogen,
The hydrolysis reaction and the polymerization reaction of the titanium alkoxide are controlled, and the solubility of the polymer formed in the solution in an organic solvent can be improved. As a specific example of the method of adding a compound having active hydrogen, there is a method of adding a compound having active hydrogen to a titanium alkoxide solution and then adding water to perform hydrolysis and a polymerization reaction. By adding an appropriate amount of the compound having active hydrogen, the hydrolysis reaction and the polymerization reaction of the titanium alkoxide can be controlled, and the solubility of the polymer formed in the solution in an organic solvent can be improved. As the compound having active hydrogen, a compound represented by the general formula [3] R ₃ COCH ₂ COR ₄ (provided that
Wherein R ₃ and R ₄ represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms), or a salicylic acid alkyl ester. More specifically, the use of ethyl acetoacetate and isopropyl acetoacetate as the β-diketone compound, and the use of ethyl salicylate and methyl salicylate as the alkyl salicylate are recommended. The amount of the compound having active hydrogen is about 0.05 to 1 mol per 1 mol of titanium alkoxide.
It is about 1.9 mol, preferably about 0.1 to about 1.0 mol. When the addition amount is less than about 0.05 mol, the effect of addition is not recognized, and when the addition amount is more than 1.9 mol,
The hydrolysis and the polymerization reaction are suppressed too much, so that the polymerization hardly proceeds, and the amount of residual organic matter in the obtained polymer also increases,
As a result, the mechanical strength of the resulting titania fiber may be low.

Step (2) of the production method is a step of dissolving the polymer in an organic solvent in which the polymer is soluble to obtain a spinning solution. The organic solvent may be any as long as it dissolves the polymer obtained in the step (1). Examples thereof include alcohols such as ethanol and isopropyl alcohol, ethers such as tetrahydrofuran and diethyl ether, and aromatics such as benzene and toluene. Hydrocarbons. When performing the step (2) of the production method, the polymer is dissolved in an organic solvent to prepare a polymer solution, and then concentrated by removing the organic solvent by heating or removing the organic solvent by reduced pressure. Is adjusted to be about 50% by weight to about 80% by weight. The viscosity (at 40 ° C.) of the spinning solution may be generally in the range of about 10 poise to about 2000 poise, preferably about 20 poise to about 1500 poise. The viscosity of the spinning solution can be controlled by adjusting the concentration of the polymer and the temperature of the spinning solution.

Step (3) of the production method is a step of spinning the spinning solution to obtain precursor fibers. For spinning, spinning methods such as nozzle extrusion spinning, centrifugal spinning, and blow spinning can be applied. At the time of spinning, the precursor fiber can be drawn by a rotating roller or a high-speed air stream. In spinning, adjusting the spinning atmosphere and the temperature and humidity of the blown air is a desirable method for stably obtaining good fibers.

Step (4) of the production method is a step of firing the precursor fiber to obtain a fired fiber. The calcination may be adjusted so that the BET surface area of the obtained titania fiber is 0.5 m ² / g or less, and usually about 300 ° C. to about 100 ° C.
It may be performed at 0 ° C., preferably at about 400 ° C. to about 900 ° C. When performing the step (4) of the manufacturing method, the precursor fiber may be subjected to a steam treatment before and / or during firing for the purpose of removing an organic solvent and the like. Steam treatment is
What is necessary is just to perform using a well-known apparatus, such as a thermo-hygrostat and a baking furnace,
Usually, the temperature of the steam treatment is about 50 ° C. or more, preferably about 60 ° C. to about 300 ° C., and the contact time is 10 minutes or more.

Further, when performing the above-mentioned method for producing titania fiber, silica may be contained in the fired fiber for the purpose of increasing the mechanical strength of the obtained titania fiber for photocatalyst. Specific examples of the method of adding silica include a method of adding a silicon compound to a titanium alkoxide solution, a method of adding a silicon compound to a solution obtained by hydrolyzing and polymerizing a titanium alkoxide solution, or a method of adding a silicon compound to a spinning solution. There is a method of adding a silicon compound. The silicon compound is not particularly limited as long as it can be uniformly mixed and dispersed in a titanium alkoxide solution and an organic solvent, but is usually represented by the general formula [4] Si _n O _n-1 (OR ₅ ) _{2n + 2} (however, Wherein R ₅ represents an alkyl group having 1 to 4 carbon atoms, and n represents 1
It is preferable to use an alkyl silicate represented by the above number). Particularly preferred alkyl silicates are those in which R ₅ in the general formula [4] is an ethyl group,
Is 4 to 6 and ethyl silicate. The amount of the silicon compound added is such that the silica content in the titania fiber obtained after firing is about 1 to about 40% by weight, preferably about 5 to about 30% by weight. If the silica content exceeds 40% by weight, the mechanical strength of the fibers obtained no longer increases.

Next, the present invention is characterized in that titanium oxide is supported on titania fibers. Titanium oxide is supported by, for example, preparing a coating agent containing titanium oxide powder, applying the coating agent to titania fibers, and baking (hereinafter, referred to as a powder coating method), and hydrolyzing titanium alkoxide. A method of immersing titania fibers in a polymer and firing it (hereinafter referred to as a polymer immersion method), a sol-gel method, a CV
D method and the like. In the present invention, the loading ratio of the titanium oxide varies depending on the single fiber diameter of the titania fiber and the like and is not unique, but is usually about 10% by weight to 50% by weight, preferably about 15% by weight based on the obtained photocatalytic titania fiber. %
About 30% by weight. If the loading is less than about 10% by weight, titania fibers for photocatalyst having high photocatalytic activity may not be obtained. If the amount is more than about 50% by weight, the effect corresponding to the increase in the loading may not be obtained.

As the titanium oxide powder used in the powder coating method, known titanium oxide powder, vapor phase titanium oxide powder, sulfuric acid titanium oxide powder, and chlorine titanium oxide powder can be used.
In performing the powder coating method, titanium oxide powder is prepared from a group consisting of alcohols such as ethanol and isopropyl alcohol, ethers such as tetrahydrofuran and diethyl ether, and aromatic hydrocarbons such as benzene and toluene. It is dispersed in a solvent to prepare a coating agent.
Next, after applying the coating agent to the titania fiber, the obtained titania may be fired. As the polymer used in the polymer dipping method, for example, the polymer obtained in step (1) of the method for producing titania fibers can be used.
When performing the polymer immersion method, the polymer is ethanol,
A precursor is prepared by adding a solvent selected from the group consisting of alcohols such as isopropyl alcohol, ethers such as tetrahydrofuran and diethyl ether, and aromatic hydrocarbons such as benzene and toluene. Next, after immersing the titania fiber in the obtained precursor, the obtained titania may be fired. Firing usually takes about 30
0 ° C to about 1000 ° C, preferably about 400 ° C to about 900 ° C
° C. If the firing temperature exceeds about 1000 ° C,
When the specific surface area of the supported titanium oxide decreases or the crystal structure of the supported titanium oxide changes, the photocatalytic activity of the obtained photocatalytic titania fiber may decrease.

The titania fiber for photocatalyst obtained by the production method of the present invention usually has a single fiber diameter of about 5 μm to about 100 μm.
μm, a fiber length of 50 cm or more, a tensile strength of about 1 GPa or more, and a titania fiber for photocatalyst having high photocatalytic activity, in which titanium oxide does not fall off during use.

When applying the titania fiber for photocatalyst obtained by the production method of the present invention, the titania fiber is processed into strands or yarns or processed into a woven fabric, for example, to form a filter, and the titania fiber is excited to have a photocatalytic effect. Irradiation with the light to wake up may be performed. As a light source,
A high-pressure mercury lamp or the like can be used, and the irradiation time (average irradiation time when the decomposition treatment is of a continuous type) differs depending on the type and concentration of the organic compound to be subjected to the decomposition treatment, and is not unique. 0.5 hours to about 50 hours.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples.
The fiber diameter, tensile strength, crystal structure, and BET specific surface area were measured by the following methods. Fiber diameter: The sample was observed with an optical microscope, 20 fibers present in the visual field were randomly selected, the fiber diameter was measured, and the average was calculated to be the fiber diameter. Tensile strength: The fiber was measured with a single fiber automatic tensile tester (manufactured by Toyo Baldwin Co., Ltd., control unit; model AMF-C, tensile unit; TENSILON, UTM-2-20), measuring length 25 mm, tensile speed 1 mm / Pull in minutes,
The breaking strength of the fiber was defined as the tensile strength. The measured value is the average value of the tensile strength of 30 single fibers. Crystal structure: The fiber was lightly ground in a mortar and analyzed using an X-ray diffractometer (RAD-IIA, manufactured by Rigaku Corporation). BET specific surface area: The fiber was lightly pulverized in a mortar and measured using Micrometrics Flowsorb II 2300 (manufactured by Shimadzu Corporation).

Example 1 Titanium isopropoxide (first-class reagent, manufactured by Wako Pure Chemical Industries)
300.0 g and 54.9 g of ethyl acetoacetate (special grade of reagent, manufactured by Wako Pure Chemical Industries) were dissolved in 700.0 g of isopropyl alcohol (special grade of reagent, manufactured by Wako Pure Chemical Industries) as a solvent, and the mixture was dissolved in a nitrogen atmosphere for 1 hour. By refluxing, a titanium alkoxide solution was prepared. At this time, the molar ratio of ethyl acetoacetate to titanium isopropoxide is 0.40. 51.0 g of water was mixed with 460.2 g of isopropyl alcohol to prepare an isopropyl alcohol solution having a water concentration of 10% by weight. This water content is 2.7 moles per mole of titanium alkoxide.

The titanium alkoxide solution was heated in a nitrogen atmosphere and refluxed under boiling. At the same time, an isopropyl alcohol solution having a water concentration of 10% by weight was added with stirring while distilling isopropyl alcohol. The distillation rate and the addition rate of isopropyl alcohol were adjusted to be substantially equal, and the addition time was adjusted to be 135 minutes. From the time when the addition was started and the isopropyl alcohol solution in which the amount of water was 2.1 mol amount was added to 1 mol of the titanium alkoxide, the precipitation of the polymer started, and when the entire amount of the isopropyl alcohol solution was added, It became a slurry completely. Analysis of the water in the distilled isopropyl alcohol revealed that the water was 0.19 mole per mole of titanium alkoxide.

After refluxing the slurry for one hour,
Isopropyl alcohol was distilled off by heating as it was, and heating was continued in an oil bath at 143 ° C. until no distillate was generated, to dry the polymer. The polymer after drying was a yellow powder, and the weight was 144 g. The amount of water discharged out of the system by this operation was 0.61 mol per 1 mol of titanium alkoxide. Therefore,
The difference between the amount of water added and the amount of water discharged out of the system together with isopropyl alcohol [2.7− (0.19+
0.61)] is based on 1 mol of titanium alkoxide.
The amount was 1.80 mol.

The polymer was dissolved in 460 g of tetrahydrofuran (Wako Pure Chemical Industries, special grade of reagent). This is designated as polymer solution A. Ethyl silicate 4 was added to this polymer solution A.
0 (Tama Chemical Industry) was added and refluxed for 1 hour to obtain a polymer solution B. The amount of ethyl silicate added is such that the titania fiber obtained by spinning and firing becomes 15% by weight as silica.

The polymer solution B was filtered through a Teflon 3 μm membrane filter, heated to distill off tetrahydrofuran and concentrated to obtain 200 g of a spinning solution. At this time, the viscosity of the spinning solution was 50 poise at 40 ° C.

The spinning solution at 40 ° C. was extruded with a nitrogen gas at 20 kg / cm ² from a nozzle having a diameter of 50 μm and 500 holes into an air atmosphere at 40 ° C. and 60% RH. Was removed at a speed of 70 m / min to obtain a continuous precursor fiber. The obtained precursor continuous fiber was placed in a constant temperature and humidity chamber at 70 ° C. and 70% RH and subjected to steam treatment for 30 minutes, and then heated at a rate of 200 ° C./hr at 900 ° C. for 30 minutes in air. By firing, a titania fiber was obtained.

The obtained titania fiber has a single fiber diameter of 15
μm, and the BET specific surface area was 0.2 m ² / g. According to XRD analysis, the crystal structure of the titania fiber was anatase.

The titania fibers (500 bundles) were wound directly around the outside of a cylinder (outside diameter 55 mm, height 90 mm) obtained by rolling a 6 mesh SUS wire mesh so that no gap was formed between the fiber bundles. . The height of the wound part is 7
0 mm. The weight of the titania fiber used for winding was 3.7 g, and the basis weight was 230 g / m ² . This is designated as substrate A.

A polymer solution A obtained in the same manner as in the above-mentioned method for producing titania fiber was used as a precursor to be calcined to form anatase type titanium oxide. After impregnating the polymer solution A with the base material A, the base material A was pulled up and dried, and then placed in a thermo-hygrostat at 85 ° C. and 95% RH, and subjected to a steam treatment for 15 hours. Then, the obtained substrate A was
Calcination was carried out at ℃ for 1 hour. The fired substrate A is converted to a photocatalyst A
And The titania fiber for photocatalyst wound around photocatalyst A had a tensile strength of 1.4 GPa. Also,
The weight of the titania fiber and the titania fiber for photocatalyst was measured, and the amount of titanium oxide supported on the titania fiber for photocatalyst was measured.
g, and the loading ratio on the titania fiber for photocatalyst is 25.
%Met.

The photocatalyst A was placed at the center of a glass-separable reaction vessel made of Pyrex (inner diameter 9 cm × length 13 cm), and an excitation light source was placed inside a wire mesh. A 100 W high-pressure mercury lamp (manufactured by Ushio Inc.) equipped with a Pyrex light source cooling tube was used as an excitation light source (ultraviolet rays of 300 nm or less were cut).

Water 600 containing a phenol concentration of 20 ppm
mL into the above-mentioned reaction vessel, and air is supplied at 200 mL / min.
Phenol was decomposed at room temperature while blowing. After irradiation with excitation light for a predetermined time to cause a decomposition reaction, the phenol concentration in the reaction solution was measured by gas chromatography analysis. The phenol concentration after exposure to excitation light for 4 hours is 1p
pm or less. In addition, about the reaction solution 5 hours after irradiation with the excitation light, the absorption spectrum derived from aromatics (210 n
m and 270 nm), no absorption spectrum was detected and phenol was completely decomposed. During the above photolysis experiment, there was no turbidity of the reaction solution accompanying the dropout of titanium oxide.

Next, in order to evaluate the adhesion of titanium oxide to the titania fiber for photocatalyst, the photocatalyst A used above was immersed in 1 L of pure water and subjected to ultrasonic treatment. After sonication for 6 hours, the weight was measured. As a result, the loading ratio of titanium oxide in the titania fiber for photocatalyst after the ultrasonic treatment was 21%, and the degree of decrease in the loading ratio was 16%.

Example 2 Titanium oxide powder P-25 (manufactured by Nippon Aerosil Co., Ltd.)
Was dispersed in ethanol to prepare a coating agent (titanium oxide 10% by weight). Substrate A produced in the same manner as in Example 1
The coating solution was applied, dried, and baked at 500 ° C. for 1 hour. The fired substrate A is referred to as a photocatalyst B. The titania fiber for photocatalyst wound around photocatalyst B had a tensile strength of 1.4 GPa. Further, the weight of the titania fiber and the titania fiber for photocatalyst was measured, and the carried amount of titanium oxide supported on the titania fiber for photocatalyst was measured. As a result, the carried amount of titanium oxide was 1.0 g. Was 21%.

The photocatalyst B was placed at the center of a Pyrex glass separable reaction vessel (inner diameter 9 cm × length 13 cm), and an excitation light source was placed inside a wire mesh. A 100 W high-pressure mercury lamp (manufactured by Ushio Inc.) equipped with a Pyrex light source cooling tube was used as an excitation light source (ultraviolet rays of 300 nm or less were cut).

Water 600 containing a phenol concentration of 20 ppm
mL into the above-mentioned reaction vessel, and air is supplied at 200 mL / min.
Phenol was decomposed at room temperature while blowing. After irradiation with excitation light for a predetermined time to cause a decomposition reaction, the phenol concentration in the reaction solution was measured by gas chromatography analysis. The phenol concentration after exposure to excitation light for 3 hours is 1p
pm or less. In addition, regarding the reaction solution 4 hours after the irradiation with the excitation light, the absorption spectrum (210 n
m and 270 nm), no absorption spectrum was detected and phenol was completely decomposed. During the above photolysis experiment, there was no turbidity of the reaction solution accompanying the dropout of titanium oxide.

The adhesion of titanium oxide was evaluated in the same manner as in Example 1. After sonication for 6 hours, the weight was measured. As a result, the loading ratio of titanium oxide in the titania fiber for photocatalyst after the ultrasonic treatment was 17%, and the degree of decrease in the loading ratio was 19%.

Comparative Example 1 The procedure of Example 1 was repeated, except that E glass fiber was used instead of titania fiber. The weight of the E glass fiber used for winding was 5.0 g, and the basis weight was 310 g / m.
^{Was 2} . This is designated as substrate C.

Titanium oxide was supported on titania fibers in the same manner as in Example 2. 1.0 g of supported titanium oxide
And the loading was 17%. This is designated as photocatalyst C.

A phenol decomposition experiment was performed in the same manner as in Example 1. After irradiation with excitation light for a predetermined time to cause a decomposition reaction, the phenol concentration in the reaction solution was measured by gas chromatography analysis. The phenol concentration 3 hours after irradiation with the excitation light was 1 ppm or less. Further, as a result of measuring the absorption spectrum (210 nm and 270 nm) derived from aromatics of the reaction solution 4 hours after the irradiation of the excitation light, no absorption spectrum was detected and phenol was completely decomposed. During the photolysis experiment described above, the reaction solution was clouded due to the dropout of titanium oxide.

The adhesion of titanium oxide was evaluated in the same manner as in Example 1. After sonication for 6 hours, the weight was measured. As a result, the loading ratio of titanium oxide in the titania fiber for photocatalyst after the ultrasonic treatment was 3%, and the degree of decrease in the loading ratio was 82%.

[0044]

As described above in detail, according to the production method of the present invention, titania fiber for photocatalyst having high photocatalytic activity and high tensile strength without titanium oxide falling off at the time of use can be industrially easily produced. In the fields of decomposition and removal of NOx, odorous substances and harmful substances, purification of polluted rivers and lakes, decolorization of dyeing wastewater, wastewater treatment, and water treatment, the industrial value is It is very large.

Continued on the front page F-term (reference) 4G047 CA02 CB05 CC03 CD05 4G069 AA03 AA08 BA04A BA04B BA15A BA15B BA26A BA26B BA37 BA38 BA48A BD05A BD05B CA05 CA10 CA13 CA17 DA05 EA03X EA03Y EB18X EB18 BA03 FB033

Claims (3)

[Claims] 1. A method for producing a titania fiber for a photocatalyst, wherein titanium oxide is supported on a titania fiber having a BET surface area of 0.5 m ² / g or less. 2. The method for producing titania fiber for photocatalyst according to claim 1, wherein the loading ratio of titanium oxide is 10% by weight to 50% by weight based on the titania fiber for photocatalyst. 3. The titania fiber is obtained by a method selected from the group consisting of a method of spinning and firing a liquid containing polytitanoxane, a sol-gel method, and a method of spinning and firing a liquid containing polytitanoxane and a silicon compound. The method for producing titania fiber for photocatalyst according to claim 1 or 2, which is a titania fiber.