JP2010063979A - Method for manufacturing photocatalyst fiber - Google Patents

Abstract

Provided is a method for producing a photocatalytic fiber that is suitable for stable production with good workability, can wind up a light-transmitting fiber coated with a solution, and has a titanium oxide layer having a high strength.
A solution of titanium tetraalkoxide or a mixture of titanium tetrahalide and β-diketone is applied to the surface of a light transmitting fiber, wound up online as it is, and then fired.
[Effect] By mixing β-diketone, hydrolysis is suppressed and the pot life is prolonged, so that workability is good and suitable for stable production. Methanol or ethanol dries quickly, and even if the light-transmitting fiber coated with the solution is wound up online as it is, the fibers do not adhere to each other and the thickness of the film does not become uneven. The titanium oxide layer is difficult to peel off.
[Selection] Figure 1

Description

  The present invention relates to a method for producing a photocatalytic fiber. More specifically, the pot life of the solution is long, the workability is good, and it is suitable for stable production.Furthermore, even if the light-transmitting fiber coated with the solution is wound up online as it is, the fibers stick together, The present invention relates to a method for producing a photocatalytic fiber in which the thickness of the film does not become uneven, and further, the strength of the titanium oxide layer is strong and hardly peeled off.

  A photocatalyst exhibits catalytic activity when irradiated with light, and is an excellent catalyst capable of reacting at room temperature. As a substance that exhibits a photocatalytic effect, titanium oxide has the highest performance and is frequently used.

  Moreover, since the photocatalyst does not have a catalytic effect unless it is exposed to light, it is a problem how efficiently the light is applied to the catalyst. As one solution to this problem, a method of forming a titanium oxide layer on the surface of a light transmitting fiber that transmits light inside, such as glass fiber, has been implemented. When a large number of such photocatalyst fibers are introduced into the liquid to be treated and the inside of the photocatalyst fiber is irradiated with light, organic substances and the like are oxidized or decomposed by the catalyst excited by light. Moreover, there exists an advantage that irradiation of the light to a catalyst is not prevented by a to-be-processed liquid (refer patent document 1).

As a method for forming a homogeneous titanium oxide layer, a method called a sol-gel method is said to be most excellent. In a general sol-gel method, a titanium alkoxide is hydrolyzed to form a solution, this solution is applied to the surface of an object to be formed, dried and then heated and fired to obtain a titanium oxide layer (see Patent Document 2). ).
JP-A-9-299937 JP 2004-292191 A

When the titanium oxide layer is formed on the surface of the light transmitting fiber by the conventional sol-gel method, there is no problem with respect to the catalytic activity.
However, since the pot life of the solution is short, workability is poor, and there is a disadvantage in stable production. In addition, since the solution applied to the surface of the light-transmitting fiber is sticky and soft for a long time, when the light-transmitting fiber coated with the solution is wound on-line as it is, the fibers adhere to each other, or the film thickness is reduced by mutual pressure. There was a problem that became uneven. Further, the strength of the titanium oxide layer is weak and there is a problem that it is easily peeled off.
Therefore, the object of the present invention is that the pot life of the solution is long, the workability is good, suitable for stable production, and even if the light-transmitting fiber coated with the solution is wound online as it is, the fibers adhere to each other, It is an object of the present invention to provide a method for producing a photocatalytic fiber that does not cause uneven film thickness due to mutual pressure, and that the titanium oxide layer is strong and difficult to peel off.

  In the first aspect, the present invention applies a mixed methanol solution or mixed ethanol solution (5) of titanium tetraalkoxide and β-diketone to the surface of the light transmitting fiber (3), winds up online, and then fires. A method for producing a photocatalytic fiber is provided.

The light transmitting fiber (3) may be any material that allows light to pass through it, and is a glass fiber, a plastic fiber, or the like, and an optical fiber is particularly preferable. Of these, a so-called leaking optical fiber is preferable. This is because, in a normal optical fiber, the light entering the inside is totally reflected and does not go outside, but travels inside, but in the case of this leaking optical fiber, it goes outside and irradiates the photocatalyst on the surface with light. .
The diameter of the light transmitting fiber (3) is arbitrary, but is preferably about 0.05 to 0.5 mm in order to give flexibility and catalyst efficiency. Moreover, the light transmission fiber (3) may be composed of a plurality of layers.

  The titanium tetraalkoxide is titanium tetramethoxide, titanium tetraisopropoxide, etc., and titanium tetraisopropoxide is excellent.

  Examples of the β-diketone include acetylacetone, propionylacetone, and benzoylacetone, and acetylacetone is preferred.

  It is known that β-diketone has a skeleton in which two ketone groups are bonded to one carbon atom, and the two oxygen atoms and metal atom are coordinated. In the present invention, the hydrolysis reaction of titanium alkoxide is suppressed by coordination with a titanium atom. For this reason, the pot life of a solution becomes long, workability | operativity is good, and it is suitable for the stable production. This coordination bond is easily desorbed and decomposed during dehydration condensation during firing and does not inhibit the reaction.

  The concentration of the mixed methanol solution or mixed ethanol solution (5) is about 0.05 to 0.3 mol of titanium tetraalkoxide and about 0.1 to 1.0 mol of β-diketone in 1 liter of methanol or ethanol. . It is preferable to make the β-diketone excessive in molar ratio.

  The mixture of titanium alkoxide and acetylacetone may be separately dissolved in methanol or ethanol and mixed. In this way, uniform mixing is possible and the reaction becomes smooth.

  The application method of the mixed methanol solution or the mixed ethanol solution (5) is generally an immersion method, but may be sprayed or other methods.

  In this invention, the light transmission fiber (3) which apply | coated the mixed methanol solution or the mixed ethanol solution (5) is wound up online as it is. This is because methanol or ethanol has a low boiling point, so the mixed methanol solution or mixed ethanol solution (5) applied to the light transmitting fiber (3) is immediately dried and can be wound up online. This is very convenient and is a great merit in terms of work area and work process. On the other hand, the conventional sol-gel method cannot be wound up online as it is because of slow drying.

  Baking is preferably performed at 400 ° C to 600 ° C. In terms of time, it is about 30 minutes to 1 hour. This firing may be performed with the wound roll as described above, or may be performed after cutting into a predetermined size.

The thickness of the titanium oxide layer (11) is 0.3 μm or more, preferably 1 μm or more. This is because 1 μm is said to be necessary to exhibit a sufficient effect as a photocatalyst.
The titanium oxide layer (11) produced by the production method of the present invention is denser and harder than the titanium oxide layer formed by the sol-gel method, and hardly peels off.

  In the second aspect, the present invention applies a mixed methanol solution or mixed ethanol solution (5) of titanium tetrahalide and β-diketone to the surface of the light transmitting fiber (3), winds up online, and then fires. A method for producing a photocatalytic fiber is provided.

  In the method for producing a photocatalytic fiber according to the second aspect, titanium tetrahalide is used instead of titanium tetraalkoxide in the method for producing a photocatalytic fiber according to the first aspect.

  The titanium tetrahalide is titanium tetrachloride, titanium tetrabromide, titanium tetrafluoride, etc., and titanium tetrachloride is excellent.

  In the production method of the present invention, the mixed methanol solution or mixed ethanol solution (5) is applied to the light transmitting fiber (3) and wound up, and the firing step is essential. It is free to include a process, a stirring process and others.

  The photocatalyst fiber (10) produced by the present invention may be used as a bundle of 100 to several thousand fibers, or may be used as a woven fabric. Applications can be used for water treatment, deodorization, antibacterial, etc. as filters, clothes, and packaging containers.

  In the water treatment field, the bundle may be introduced into a liquid reactor, and the inside of the photocatalyst fiber (10) may be irradiated with ultraviolet rays or visible light. Moreover, you may introduce a bundle directly in the pond with a to-be-processed liquid, or a water storage tank.

Next, a suitable example of water treatment will be described.
It has been found that the continuous cropping failure in hydroponics is due to hormone-like substances produced by the plants themselves, and conventionally, a photocatalyst coated on the walls and bottom of hydroponics bats has been proposed. However, it is necessary to irradiate the entire photocatalyst coated on the bat, which increases the size of the apparatus and increases the cost.
On the other hand, when a bundle of photocatalyst fibers (10) according to the present invention is used, the reactor becomes extremely compact, and a purification device with reduced running costs can be achieved by using ultraviolet LEDs. Since only organic substances in the aqueous solution containing inorganic nutrients (nitrogen, phosphoric acid, potash) can be selectively decomposed and removed, the cost of fertilizer can be suppressed. It is most suitable for hydroponic cultivation in a narrow area in a special environment such as an aseptic plant production factory, highland, and space.

  It can also be used for water purification equipment such as drinking water. It is also suitable for on-demand purification and disinfection equipment.

  The primary wastewater generated by the conversion of livestock excrement into fertilizer and fuel contains high-concentration organic matter and is difficult to dispose of as it is. The processing apparatus using the bundle of photocatalyst fibers (10) according to the present invention can be processed efficiently. Then, it becomes possible to use intermediate water such as irrigation, barn washing, and air coolers.

  Since the dyeing waste liquid contains a pigment at a high concentration, it is usually separated by settling by adding a precipitant. Since sludge remains as waste, environmental load and treatment costs were major problems. If the liquid processing apparatus using the photocatalyst fiber (10) according to the present invention is used, the light transmittance of the solution is unnecessary, so that high-concentration waste water can be treated as the stock solution.

The photocatalyst fiber (10) according to the present invention can be used not only for decomposition and purification of organic substances but also as a microchannel reactor for performing a controlled photochemical reaction. In a normal microreactor, a reaction solution is passed through a thin tube formed on a glass substrate, and a catalyst layer and an active layer introduced into the wall surface of the thin tube are reacted with substances in the solution. This has the major disadvantage that the production cost of the reactor is high.
However, in the photocatalyst fiber (10) according to the present invention, the titanium oxide layer (11) is not easily peeled off, and microchannels are formed in the gaps between the photocatalyst fibers (10) that are packed tightly just by bundling. Downscaling and scaling up are easily possible.

The present invention has the following effects.
-Alcohol solution of titanium tetraalkoxide is hydrolyzed by moisture in the air and cannot be used in a short time. On the other hand, in the present invention, since the progress of hydrolysis is suppressed by β-diketone, it can be used for about half a year if attention is paid to evaporation of methanol or ethanol. That is, the pot life of the mixed methanol solution or mixed ethanol solution (5) is long, the workability is improved, and it is advantageous for stable production. .
-Since fast-drying methanol or ethanol is used, after application of the mixed methanol solution or mixed ethanol solution (5), it is dried quickly and can be wound online as it is. This is very advantageous in terms of work area and work time.
-The strength of the formed titanium oxide layer (11) is large and it is difficult to peel off.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

In the coating / winding apparatus 1 shown in FIG. 1, in the coating tank 4, 0.71 g of titanium tetraisopropoxide is dissolved in 25 ml of ethanol, and 25 ml of an ethanol solution of acetylacetone (0.5 mol / l) is added thereto. The mixed ethanol solution 5 stirred for 12 hours is put.
A light transmitting fiber (for example, quartz glass fiber: diameter 0.125 mm) 3 is pulled out from the light transmitting fiber roll 2, immersed in the mixed ethanol solution 5 in the coating tank 4, pulled up, and then adjusted in film thickness with the die 6. The coated fiber 7 is made to run in the air for about 10 seconds, and then wound around the coated fiber roll 8.

  After that, the coated fiber 7 cut into a predetermined length (for example, 15 cm) was put into the electric furnace 9 shown in FIG. 2, and heated and fired at 600 ° C. for about 1 hour to produce the photocatalyst fiber 10 shown in FIG. . In addition, since the surface of the coating fiber 7 is already dry, it can be put in close contact with each other. In this sense, manufacturing efficiency can be improved.

FIG. 3 shows the produced photocatalytic fiber 10.
The pencil hardness of the titanium oxide layer 11 was 6H or more.

  The mixed ethanol solution 5 could be used for about half a year.

In the coating / winding apparatus 1 shown in FIG. 1, in a coating tank 4, 1.0 g of titanium tetrachloride is dissolved in 10 ml of methanol, and a methanol solution of acetylacetone (0.18 g / 10 ml) is added thereto, and methanol is further added. The mixed methanol solution 5 which added 10 ml and stirred for 12 hours is put.
A light-transmitting fiber (for example, quartz glass fiber: diameter 0.125 mm) 3 is pulled out from the light-transmitting fiber roll 2, immersed in the mixed methanol solution 5 in the coating tank 4, pulled up, and adjusted in film thickness with a die 6. The coated fiber 7 is made to run in the air for about 10 seconds, and then wound around the coated fiber roll 8.

  After that, the coated fiber 7 cut into a predetermined length (for example, 15 cm) was placed in the electric furnace 9 shown in FIG. . In addition, since the surface of the coating fiber 7 is already dry, it can be put in close contact with each other. In this sense, manufacturing efficiency can be improved.

FIG. 3 shows the produced photocatalytic fiber 10.
The pencil hardness of the titanium oxide layer 11 was 6H or more.

  The mixed methanol solution 5 could be used for about half a year.

FIG. 4 is a cross-sectional view showing a photocatalyst solution processing apparatus 100 using the photocatalytic fiber 10 according to the present invention.
This photocatalyst processing apparatus 100 is a partition wall in which the photocatalyst fiber 10 according to the present invention is cut into 15 cm, the end surface on the light incident surface 12a side is optically processed, and 1000 pieces are bundled into a bundle cylinder 13 having an inner diameter of about 5 mm. 14 and 15 are fixed. The portion of the bundle cylinder 13 located between the partition walls 14 and 15 has an opening 13a.

  For example, ultraviolet light L is incident on the light incident surface 12a from the light source 16 including a 500 W high-pressure mercury lamp and an ultraviolet bandpass filter, the stock solution A is introduced from the stock solution inflow surface 12b of the bundle cylinder 13, and the processing solution B is flowed out from the opening 13a.

FIG. 5 shows the photocatalyst solution processing apparatus 100 viewed from the light incident surface 12a side.
In FIG. 5, the photocatalytic fiber 10 is omitted.

A methylene blue aqueous solution (250 μmol / l, pH 3) was supplied as a stock solution A to the photocatalyst treatment apparatus 100 at a flow rate of 3.5 ml / min. Since the bundle cylinder 13 has an inner diameter of about 5 mm, the time required to pass the bundle cylinder 13 once is about 20 seconds.
The absorbance change at 670 nm characteristic of methylene blue was measured with Shimadzu UV-2400PC, and the decomposition rate was measured.
As a result of passing through the photocatalyst solution processing apparatus 5 five times, the decomposition rate was 60%.

-Comparative Example 1-
0.71 g of titanium tetraisopropoxide was dissolved in 50 ml of ethanol and stirred for 12 hours to prepare an ethanol solution.
This ethanol solution became unusable in one day.

-Comparative Example 2-
Under a nitrogen stream, tetra-n-butoxytitanium (12.5 mmol) and diethylene glycol (hydrolysis inhibitor, 24 mmol) were added to a solvent (n-butanol, 7.36 ml) and mixed. In parallel with this, ion-exchanged water (reaction initiator, 25 mmol) and hydrazine-hydrochloride (salt catalyst, 0.125 mmol) were added to the solvent (n-butanol, 10 ml) and mixed. Next, these two types of mixed solutions were combined and stirred and mixed in an incubator adjusted to 25 ° C. for 2 hours to obtain a mixture sol.
This sol was applied by a dipping method onto the surface of a quartz glass fiber cut in advance to a predetermined length. Since the surface was sticky as it was, it was calcined at 400 ° C. for 10 seconds. Then, it baked at 600 degreeC for about 1 hour.
The pencil hardness of the titanium oxide layer of the produced photocatalytic fiber was F to HB.

It is explanatory drawing which shows the application | coating and winding process in the manufacturing method of the photocatalyst fiber of this invention. It is explanatory drawing of the baking process in the manufacturing method of the photocatalyst fiber of this invention. It is a perspective view which shows the photocatalyst fiber manufactured by the manufacturing method of the photocatalyst fiber of this invention. It is sectional drawing which shows the photocatalyst liquid processing apparatus using the bundle of the photocatalyst fiber which concerns on this invention. It is the schematic diagram seen from the light-incidence surface side of FIG.

Explanation of symbols

3 Light transmission fiber 5 Mixed methanol solution or mixed ethanol solution 7 Coating fiber 8 Coating fiber roll 9 Electric furnace 10 Photocatalyst fiber 11 Titanium oxide layer

Claims (2)

  A method for producing a photocatalytic fiber comprising applying a mixed methanol solution or mixed ethanol solution (5) of titanium tetraalkoxide and β-diketone to the surface of the light transmitting fiber (3), winding it online, and then firing it. .   Production of photocatalytic fiber characterized in that a mixed methanol solution or mixed ethanol solution (5) of titanium tetrahalide and β-diketone is applied to the surface of the light transmitting fiber (3), wound up online, and then fired. Method.

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