JPH09253505A - Photocatalyst fiber and device to remove harmful material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the area contributing to the photocatalytic reaction and to prevent photocatalyst fine particles from dropping by fixing photocatalyst particles to the surface of vitreous spheres and depositing the vitreous sphered on at least a part of an optical fiber having a light-leaking part. SOLUTION: Photocatalyst fine particles 3 which consists of a semiconductor crystal are irradiated with light of long wavelength corresponding to the energy over the band gap of the semiconductor so as to oxidize and decompose harmful matters in a liquid or gas by using the photocatalytic reaction of the light emitted from the fine particles 3. In this system, the photocatalyst fine particles 3 are fixed to the surface of vitreous spheres 2 and these spheres 2 are deposited with an optically transparent adhesive on at least a part of the surface of a photocatalyst fiber having a light-leaking part 1. In this case, anatase type titanium dioxide in a crystal state especially having high oxidation power is used for the photocatalyst fine particles 3. The primary particle size of the photocatalyst particles 3 is preferably controlled to 10 to 1000Å.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocatalyst fiber for inducing a photocatalytic reaction and a harmful substance removing device using the photocatalyst fiber.

[0002]

2. Description of the Related Art In recent years, photocatalyst fine particles, which are semiconductor crystals, have been used to remove harmful substances in liquids and gases such as bacteria contained in water, trihalomethane, tobacco smoke contained in the air, and malodorous substances in toilets. Attention has been focused on a technique of irradiating fine particles with light having a wavelength corresponding to energy larger than the band gap of a semiconductor and utilizing photocatalytic reaction of light emitted from the fine particles to oxidize and decompose harmful substances. As a method of utilizing this photocatalytic reaction even in a place where light cannot reach easily, a method using an optical fiber carrying photocatalyst fine particles has been proposed.
JP-A-43841 and JP-A-6-134476 disclose that a light leak portion is formed on the surface of an optical fiber, and photocatalyst fine particles are directly stacked and supported on the light leak portion in a thin film form.

In general, in the photocatalytic reaction, the larger the area involved in the photocatalytic reaction, the higher the oxidative decomposition rate of the harmful substance. In the method disclosed in the above publication, however, the harmful substance comes into contact with the photocatalyst of the thin film surface layer portion. Since it is only fine particles and the area involved in the reaction is small, the oxidative decomposition rate is low, and it is not sufficient for the practical removal of harmful substances. Further, when the optical fiber is bent with a large curvature in order to increase the degree of light leakage, a stress is applied to the carried thin film of the photocatalyst fine particles to cause cracks, and the photocatalyst fine particles are likely to fall off.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photocatalyst fiber having a large area involved in a photocatalytic reaction and in which photocatalyst fine particles are less likely to fall off, and oxidation of harmful substances using the photocatalyst fiber is carried out. An object of the present invention is to provide a device for removing harmful substances having a high decomposition rate.

[0005]

According to the present invention, at least the surface of an optical fiber having a light leakage portion is formed by vitreous spheres having photocatalyst fine particles fixed on the surface thereof, with or without an optically transparent adhesive. A photocatalyst fiber characterized by being partially supported,

Also, there is provided a harmful substance removing device characterized in that the photocatalytic fiber is contained in a photocatalytic reaction tank for harmful substances.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The photocatalyst particles used in the photocatalyst fiber of the present invention include metal oxide crystal particles such as titanium dioxide, zinc oxide, tungsten trioxide, niobium trioxide, etc., and sulfur compound crystal particles such as cadmium sulfide. In particular, anatase-type titanium dioxide having a crystal form with strong oxidizing power is preferable. For example, titanium dioxide photocatalyst fine particles that can be obtained as a commercially available product include Taipaque ST-01 manufactured by Ishihara Sangyo Co., Ltd. and Taki Chemical Co., Ltd. ) Titanium oxide sol manufactured by the present invention is used. Further, as the photocatalyst fine particles, those obtained by condensing a partial hydrolyzate of a metal alkoxide compound such as a titanium alkoxide compound and a zinc alkoxide compound can be used.

The preferable primary particle size of the photocatalyst fine particles is 1
When the particle size is 0 to 1000 angstroms and the particle size is less than 10 angstroms, the quantum size effect of the particles appears remarkably, and the energy (band gap) between the upper end of the valence band and the lower end of the conduction electron band of the semiconductor is high energy. When the particle size exceeds 1000 Å strong, the activity of the photocatalytic reaction becomes low. In order to cause a photocatalytic reaction in the photocatalyst fiber of the present invention, the photocatalyst fine particles are made to radiate from the light guide part of the optical fiber by irradiating with ultraviolet rays of 410 nm or less corresponding to the energy of the band gap or more to cause light leakage from the light leak part. It can be excited to induce a photocatalytic reaction.

Optically transparent hollow spheres (glass balloons) or solid spheres (glass beads) containing SiO ₂ or Al ₂ O ₃ as a main component are used as glassy spheres for fixing the photocatalyst fine particles. In particular, hollow spheres are light and have the advantage that photocatalytic fibers that float in water can be obtained. In the present invention, optically transparent means that the total light transmittance at a wavelength of 410 nm is 20% or more, and if the total light transmittance of the glassy sphere is less than 20%, the glassy sphere is transmitted. The amount of light emitted is too small to excite the photocatalyst sufficiently.

The diameter of the glassy sphere depends on the diameter of the optical fiber used and the particle diameter of the photocatalyst fine particles, but it is 1 μm to 10 m.
It is appropriately selected within the range of m. Vitreous sphere diameter is 1 μm
If it is less than 10 mm, the number of photocatalyst fine particles fixed to the glassy spheres is small and it is difficult for a sufficient photocatalytic reaction to occur. If it exceeds 10 mm, it is difficult to support the glassy spheres on the optical fiber. Further, when the glassy spheres are hollow spheres, the shell thickness is preferably 0.1 μm or more in order to maintain practical strength.

The optical fiber used in the photocatalyst fiber of the present invention is not particularly limited as long as it can guide light in the wavelength range that excites the photocatalyst of the fine particles. For example, polymethylmethacrylate resin, polycarbonate resin, polystyrene resin,
Examples thereof include plastic optical fibers made of an amorphous polyolefin resin such as poly-4-methylpentene-1 and quartz optical fibers made of quartz glass.

The optical fiber may be either a step index type optical fiber having a core / clad structure, a bare optical fiber having only a core structure or a graded index type optical fiber. In the present invention, even if the optical fiber is an optical fiber having no light leakage part, light is leaked from the bonding part by bonding the glassy sphere to the surface of the optical fiber. It is preferable that the light leakage part is formed on the surface of the fiber.

The photocatalyst fiber of the present invention comprises glassy spheres having photocatalyst fine particles fixed on the surface thereof, which is carried on the surface of the optical fiber having a light leak part, preferably on all or part of the light leak part of the surface of the optical fiber. The light leakage part of the optical fiber is formed by a method such as forming a rough surface on the surface of the optical fiber, bending the optical fiber to a curvature that causes light leakage, etc. It can be set appropriately.

In fixing the photocatalyst fine particles on the glassy sphere surface and supporting the photocatalyst fine particle-fixed glassy spheres on the optical fiber leaking portion, surface treatment is performed in advance on the surface of the glassy sphere and the optical fiber leaking portion to functionalize the functional groups. It is preferably formed.

The surface treatment includes, for example, hydrolysis of acid anhydrides such as succinic anhydride, acetic anhydride, and phthalic anhydride, which are hydrolyzed with an alkaline aqueous solution such as sodium hydroxide aqueous solution and potassium hydroxide aqueous solution to form hydroxyl groups. Substance to form a carboxyl group by dehydration reaction with the hydroxyl group on the surface of the object to be treated, treatment with a hydrolyzate of a hydrolyzable silicon compound having an epoxy group, an amino group or an alkoxy group at the molecular end, and coating with a condensate thereof, etc. Method is used.

As the hydrolyzable silicon compound in the above, γ-glycidoxypropyltrimethoxysilane, γ
-Glycidoxypropylmethyldimethoxysilane, γ-
Examples thereof include chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, tetramethoxysilane and tetraethoxysilane.

The fixing of the photocatalyst fine particles on the surface of the glassy sphere is carried out by chemically reacting the hydroxyl groups present on the surface of the glassy sphere with the hydroxyl groups present on the surface of the photocatalyst fine particle to form a chemical bond. It is carried out by a method of chemically reacting the functional group of the sphere with the hydroxyl group existing on the surface of the photocatalyst fine particles to form a chemical bond.

These chemical reactions are based on a dehydration condensation reaction for forming an ether bond, an ester bond, an amide bond, etc., and a ring-opening polymerization of an epoxy group. As a method for fixing photocatalyst fine particles, a photocatalyst on a glassy sphere is used. Examples thereof include a method of coating fine particles and causing a chemical reaction by heating in a temperature range of room temperature to 600 ° C. If the heating temperature is below room temperature, the reaction is slow, and if it exceeds 600 ° C,
The crystal morphology of the photocatalyst is apt to change and the photocatalytic activity is apt to decrease.

When the photocatalyst fine particle-fixed glassy spheres are supported on the optical fiber leaking part, when the photocatalyst finer particle-fixed glassy spheres are supported on the optical fiber leaking part only, the functional groups of the photocatalyst fine particle-fixed glassy spheres and the optical fibers are supported. It may be carried out by chemically bonding to the functional group of the light leaking part, and an optically transparent adhesive may be used, and the light leaking part of the optical fiber may be supported through this adhesive. The chemical bond for supporting the glass spheres fixed with photocatalyst fine particles on the optical fiber light leakage part is an ether bond, an ester bond, an amide bond based on a dehydration condensation reaction, and a bond based on ring-opening polymerization of an epoxy group.

As a method for supporting only one layer of the glass spheres fixed with photocatalyst fine particles on the optical fiber leaking part, for example, after dipping at least the leaking part of the optical fiber in a liquid in which the glassy spheres fixed with photocatalyst fine particles are floated on the liquid surface, 20 to 20
The heating is performed at a temperature of 600 ° C. and in a temperature range in which the optical fiber is not damaged. If the heating temperature is 20 ° C or lower, the reaction is slow,
If it exceeds 600 ° C, the chemical bond is easily broken.

FIG. 1 is a schematic side view of a photocatalyst fiber in which only one layer of glass fiber spheres fixed with photocatalyst fine particles is carried on the entire optical fiber light leak portion, and FIG. The schematic side view of the photocatalyst fiber which carried only one layer of sphere is shown, respectively.

When the glass spheres fixed with the photocatalyst fine particles are stacked and supported on the optical fiber leaking part, only the chemical bond between the functional groups is sufficient to allow the optical fiber leaking part and the glassy spheres fixed with the photocatalyst fine particles or the adjacent photocatalyst fine particles. Since a sufficient bonding strength cannot be obtained between the fixed glassy spheres and the photocatalyst fine particles fixed glassy spheres, an optically transparent adhesive is used to provide a photocatalyst between the optical fiber leaking part and the photocatalyst fine particle fixed glassy spheres or adjacent photocatalysts. The particles are fixed and the glassy spheres are bonded together.
Therefore, in the photocatalyst fiber of the present invention using an adhesive, glassy spheres having photocatalyst fine particles fixed to the surface thereof are carried on at least a part of the light leakage part of the optical fiber via an optically transparent adhesive. .

The optically transparent adhesive used has a total light transmittance of 20% at a wavelength of 410 nm as described above.
When the total light transmittance of the adhesive is less than 20%,
Sufficient excitation light does not reach the photocatalyst of fine particles. Further, the adhesive used, the refractive index is preferably the same as or smaller than the refractive index of the optical fiber and the glassy sphere, the optical fiber,
When the refractive index is larger than that of the glassy sphere, it becomes difficult for the excitation light to reach the photocatalyst by the amount of the light reflected at the interface. Furthermore, the adhesive must naturally be able to withstand the oxidative decomposition action of the photocatalyst. .

The adhesive used preferably is
(A) Condensates of hydrolyzable silicon compounds, and (b) fluororesins. As the hydrolyzable silicon compound in (a), γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-
Examples thereof include chloropropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, tetramethoxysilane and tetraethoxysilane.

The condensate of the hydrolyzable silicon compound of (a) is a solution obtained by dissolving the hydrolyzable silicon compound in a water / alcohol solution, hydrolyzing it in the presence of hydrochloric acid, acetic acid, etc., and then partially condensing it. Then, this solution is used as an adhesive.

Examples of the method for supporting the vitreous spheres fixed with photocatalyst fine particles on the optical fiber leaking part by using a condensate of a hydrolyzable silicon compound as an adhesive include, for example, a. The photocatalyst fine particle-fixed glassy spheres are floated on the partial condensation solution, at least the light leakage part of the optical fiber is immersed, and then pulled up with the photocatalyst fine particle fixed glassy spheres attached to the light leakage part, 20 to 60.
A method of curing the partial condensate by heating at a temperature of 0 ° C. and in a temperature range where the optical fiber is not damaged, b. Insert the optical fiber coated with the partial condensation solution into the container containing the photocatalyst fine particle-fixed glassy spheres, pull up with the photocatalyst fine particle-fixed glassy spheres attached to the light leak portion, and at a temperature of 20 to 600 ° C., and Heating in a temperature range that does not damage the optical fiber,
A method of curing the partial condensate is used.

Examples of the (b) fluorine-based resin include Cytop manufactured by Asahi Glass Co., Ltd. or a fluorine-based resin commercially available as Lumiflon. These fluorine-based resins can be used in a fluorine-based solvent such as 3M Fluorinert. The dissolved fluororesin solution is used as an adhesive.

As a method of supporting the photocatalyst fine particle-fixed glassy spheres on the optical fiber leaking part by using a fluororesin as an adhesive, for example, at least the leaking part of the optical fiber is soaked in a fluororesin solution, and the pulling leaking part is filled with the fluororesin. After applying the solution, insert it into a container containing photocatalyst fine particles-fixed glassy spheres, pull up with the photocatalyst fine particles-fixed glassy spheres attached to the light leaking part, and raise the temperature at 20 to 300 ° C. and damage the optical fiber. A method is used in which the solvent of the fluororesin solution is evaporated by heating in a temperature range that does not exist.

FIG. 3 is a schematic side view of a photocatalyst fiber in which glass spheres fixed with photocatalyst fine particles are laminated and supported on the entire optical fiber light leak portion through an adhesive. FIG. 4 shows a photocatalyst on a part of the optical fiber light leak portion. FIG. 2 is a schematic side view of a photocatalytic fiber in which microparticle-immobilized glassy spheres are laminated and supported with an adhesive interposed therebetween.

Further, in the photocatalyst fiber of the present invention, a hollow part may be formed between the carrying part and the light leak part or in the carrying part in the photocatalyst fine particle fixed glassy sphere carrying part via the adhesive. When formed, the contact area of the photocatalyst particles increases by the amount of the photocatalyst particle-fixed glass spheres exposed in the cavity.

In order to form the cavity portion in the glassy sphere supporting portion on which the photocatalyst fine particles are fixed, for example, an adhesive is used in the optical fiber light leaking portion to carry the glassy spheres on which the photocatalyst fine particles are fixed and the solvent-soluble fine particles are laminated and supported, and the adhesive is heated. After curing, a method of immersing in solvent and eluting the solvent-soluble fine particles is used. Examples of the solvent-soluble fine particles include fine particles made of polyvinyl alcohol resin, ethylene-vinyl acetate resin and the like, and examples of the solvent include water and water / alcohol mixed liquid.

FIG. 5 is a schematic side view of a photocatalyst fiber in which glass spheres fixed with photocatalyst fine particles are laminated and carried on all of the optical fiber light leak parts through an adhesive, and a hollow portion is formed in the carrying part.
FIG. 6 is a schematic side view of the photocatalyst fiber in which the photocatalyst fine particle-fixed glassy spheres are laminated and supported on a part of the optical fiber light leaking portion with an adhesive, and a hollow portion is formed in the supporting portion.

The photocatalyst fiber of the present invention may be prepared by a method other than the above method, in which vitreous spheres are supported on the optical fiber light-exhausting part with an adhesive and then the photocatalyst fine particles are fixed to the carried vitreous spheres. It can also be obtained, and in this case, the supporting of the glassy spheres on the optical fiber leaking part and the immobilization of the photocatalyst fine particles on the glassy spheres can be carried out by the same method as described above.

In the photocatalyst fiber of the present invention, the excitation light guided to the optical fiber travels while totally reflecting inside the optical fiber, is scattered by the light leak portion, and is the surface of the glassy sphere in contact with the light leak portion. Of the photocatalyst fine particles, or the photocatalyst fine particles on the glassy sphere surface through the optically transparent adhesive and the laminated glassy spheres. Further, in the photocatalyst fiber of the present invention, the excitation light scattered in the light leak portion,
Since the light is further scattered by the glassy sphere, the excitation light easily reaches the entire photocatalyst fine particles on the surface of the glassy sphere.

Since the photocatalyst fiber of the present invention causes a sufficient photocatalytic reaction by excitation light, it is very suitable for use in a harmful substance removing device. The harmful substance removing device of the present invention is the photocatalyst described above. This is a harmful substance removing device that incorporates fibers into a photocatalytic reaction tank for harmful substances.

7 to 9 are schematic diagrams showing examples of the harmful substance removing apparatus of the present invention. The apparatus of the present invention comprises a light source 6, a photocatalyst fiber 9 and a reaction tank 10 as main components. FIG. 7 shows an apparatus in which the photocatalyst fibers 9 are not bundled and incorporated in the reaction tank 10, FIG. 8 is an apparatus in which a large number of photocatalyst fibers 9 are bundled and incorporated in the reaction tank 10, and FIG. 9 is a curl in a spiral shape. FIG. 3 is a schematic view of each of the devices in which the photocatalyst fiber 9 is incorporated in the reaction tank 10.

7 to 9, a gas or a liquid containing a harmful substance is introduced into the reaction vessel 10 through the inlet 12 of the object to be processed, and the excitation light 7 emitted from the light source 6 is guided from the fiber end portion. The harmful substance contained in the gas or liquid of the object to be treated is oxidatively decomposed by being brought into contact with the substance 9 and is discharged from the treated substance outlet 16 as a harmless substance.

The number of photocatalyst fibers used in the apparatus, the size of the light leak portion, and the setting of the photocatalytic reaction area can be appropriately selected according to the concentration of harmful substances in the object to be treated, the flow rate, and the like.
As the light source, a white fluorescent lamp, a black light fluorescent lamp, a high pressure mercury lamp, a low pressure mercury lamp, sunlight or the like is used. The light from the light source may be directly irradiated onto the fiber end portion of the photocatalytic fiber, or may be once condensed by a condenser lens and then irradiated onto the fiber end portion of the photocatalytic fiber.

The harmful substance removing device of the present invention is applied to the purification of a gas containing a harmful substance or a liquid containing a harmful substance,
A publicly known separation membrane device can be combined with the pre-stage or the post-stage of this device to enhance purification, remove dust in gas or liquid, and separate specific components. In addition, a photocatalyst fiber and a separation membrane can coexist to form a harmful substance removing device having both a purifying function and a separating function.

[0040]

The present invention will be described below in more detail with reference to examples.

(Example 1) <Preparation of photocatalyst fine particle fixed glassy spheres> Hollow glassy spheres (Glass Bubbles S-60 manufactured by 3M, average particle diameter 3)
5 μm, average shell thickness 0.8 μm) and titanium dioxide sol (titanium oxide sol manufactured by Taki Kagaku Co., Ltd.) were put into a glass petri dish, the surface of the glassy sphere was wetted with titanium dioxide sol, and the glassy sphere was taken out and hot air was blown. 100 in the dryer
The mixture was heated at 0 ° C. for 2 hours to evaporate the titanium dioxide sol solvent on the surface of the glassy spheres. Then, the glassy spheres were heated in an electric furnace at 500 ° C. for 10 hours to prepare photocatalyst fine particle fixed glassy spheres in which titanium dioxide fine particles were fixed to the glassy spheres.

<Preparation of Optical Fiber> A graded index type quartz optical fiber having a diameter of 100 μm and a length of 50 cm was scratched with a # 2000 sandpaper on the entire surface from the tip to 15 cm to form a light leaking part. .
10% by weight of tetraethoxysilane was added to this optical fiber
/ 1000 normal hydrochloric acid and ethanol in a mixed solution prepared by hydrolysis and partial condensation, and then immersed in a solution, then pulled up and heated at 100 ° C. for 24 hours to coat the optical fiber leak part with a tetraethoxysilane condensate. . By this surface treatment, hydroxyl groups and epoxy groups were formed on the surface of the optical fiber light leak part.

<Production of Photocatalyst Fiber> The photocatalyst fine particle-fixed glassy spheres produced above were floated on the tetraethoxysilane partial condensate solution obtained in the same manner as above, and the surface-treated quartz optical fiber was placed in this solution. Immersion was performed with the photocatalyst fine particle-fixed glassy spheres attached to the optical fiber leaking part, and the glass fiber was pulled up and dried at 100 ° C. for 1 hour. Then, the mixture was heated at 200 ° C. for 2 hours to condense and cure the tetraethoxysilane partial condensate, which was an adhesive, to prepare a photocatalyst fiber in which the photocatalyst fine particle-fixed glassy spheres were laminated and supported on the light leakage part of the quartz optical fiber.

The prepared 500 photocatalyst fibers were bundled and placed in water containing 1000 ppm of trichloromethane, and an ultrahigh pressure mercury lamp was irradiated from the fiber end portion of the photocatalyst fiber bundle to guide light.
When the photocatalytic reaction was carried out while stirring the water with a stirrer, the concentration of trichloromethane in the water was 3 pp after 6 hours.
m.

(Example 2) <Preparation of photocatalyst fine particle-fixed glassy spheres> The same as Example 1 except that the hollow glassy spheres in Example 1 were replaced by solid glassy spheres having a particle diameter of 0.1 mm. Then, the photocatalyst fine particle fixed glassy spheres in which the titanium dioxide fine particles were fixed to the glassy spheres were produced.

<Preparation of optical fiber> Step index polymethylmethacrylate resin having a diameter of 200 μm and a length of 60 cm The entire surface of the optical fiber up to 15 cm from the tip is rubbed with # 1000 sandpaper to scratch and leak light. Formed. 10% by weight of γ-glycidoxypropyltrimethoxysilane was added to 1/100 of this optical fiber.
After dipping in a solution prepared by hydrolysis and partial condensation in a mixture of 0N hydrochloric acid and ethanol, pulling it up to 60
After heating at 0 ° C. for 5 minutes, the optical fiber light leak portion was coated with γ-glycidoxypropyltrimethoxysilane partial condensate. By this surface treatment, hydroxyl groups and epoxy groups were formed on the surface of the optical fiber light leak part.

<Preparation of Photocatalyst Fiber> The surface-treated optical fiber was inserted into a beaker of 250 ml capacity containing the above-prepared photocatalyst fine particle-fixed glassy sphere, and the photocatalyst fine particle-fixed glassy sphere was inserted into the entire optical fiber light-exposed portion. Is pulled up in a state of being laminated and adhered, and heated at 80 ° C. for 24 hours to condense and cure the partial condensate of γ-glycidoxypropyltrimethoxysilane, which is an adhesive, so that the titanium dioxide fine particles-fixed glassy spheres are made into a polymethylmethacrylate resin. A photocatalyst fiber laminated and supported on the light leakage portion of the optical fiber was produced.

When 500 photocatalyst fibers prepared were bundled and put in water containing 1500 ppm of chloroform, an ultrahigh pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide the light, and the photocatalytic reaction was carried out while stirring the water. After 9 hours, the concentration of chloroform in water became 11 ppm.

(Example 3) <Preparation of photocatalyst fiber> Hollow glassy spheres (Glass Bubbles S-60 manufactured by 3M, average particle diameter 35 µm, average shell thickness 0.8 µm) were added with 10% by weight of tetraethoxysilane. Was floated on a solution prepared by hydrolysis and partial condensation in a mixed solution of 1 / 1000N hydrochloric acid and ethanol.
The quartz optical fiber surface-treated in the same manner as above was dipped in this solution, pulled up with the vitreous spheres attached to the optical fiber leaking part, and dried at 100 ° C. for 1 hour. The glassy sphere was partially laminated and supported on the light leakage part of the quartz optical fiber.

Next, 10 cm ^{3 of the} same tetraethoxysilane partial condensate solution as described above was dripped onto the glassy spheres laminated and supported on the quartz optical fiber light leaking part, and allowed to penetrate between the glassy spheres, and then heated at 200 ° C. for adhesion. After the tetraethoxysilane partial condensate, which is an agent, is condensation-cured, the glassy sphere-supporting optical fiber is dipped in titanium dioxide sol (titanium oxide sol manufactured by Taki Chemical Co., Ltd.), pulled up and heated at 500 ° C. Photocatalytic fibers were prepared by fixing titanium fine particles to glass spheres.

The prepared 500 photocatalyst fibers were bundled and placed in 1 liter of brown water containing 0.7 mmg of tobacco nicotine and 9 mmg of tar, and a high pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide light. When water was subjected to a photocatalytic reaction while stirring with a stirrer, after 24 hours, the water became colorless and transparent and had no cigarette odor.

(Example 4) <Preparation of photocatalyst fine particle fixed glassy spheres> In Example 1, hollow glassy spheres were replaced with hollow glassy spheres (HSC-110B manufactured by Toshiba Ballotini Co., Ltd., average particle diameter 10 μm).
m, γ-glycidoxypropyltrimethoxysilane) was used, and photocatalyst particles-fixed glass spheres were prepared by fixing titanium dioxide particles to glass spheres in the same manner as in Example 1.

<Preparation of optical fiber> Diameter 80 μm, length 5
The entire surface of the 0 cm graded index type quartz optical fiber from the tip to 15 cm was rubbed with # 3000 sandpaper to form a scratched light leak part. This optical fiber is mixed with 15% by weight of tetraethoxysilane and γ
-Glycidoxypropyltrimethoxysilane 15% by weight
The mixture was immersed in a solution prepared by hydrolyzing and partially condensing a mixture of 1 / 1000N hydrochloric acid and ethanol, then pulled up and dried at 60 ° C. for 5 minutes, and the optical fiber light leak part was converted to tetraethoxysilane. Coated with a partial condensate of a mixture of γ-glycidoxypropyltrimethoxysilane.
By this surface treatment, hydroxyl groups and epoxy groups were formed on the surface of the optical fiber light leak part.

<Production of Photocatalyst Fiber> The photocatalyst fine particle-fixed glassy spheres prepared above and polyvinyl alcohol resin fine particles having a weight average molecular weight of 2000 and an average particle diameter of 10 μm are mixed at a weight ratio of 1: 1, and water is added to each particle. I got wet. Then, the surface-treated quartz optical fiber was inserted into this particle mixture, and the titanium dioxide fine particles-fixed glassy spheres and the polyvinyl alcohol resin fine particles were pulled up while being adhered to the entire optical fiber light-exposed portion, and the temperature was raised at 80 ° C. for 24 hours. By heating, the partial condensate used for the surface treatment of the optical fiber leaking part was condensation-cured. The obtained photocatalyst fiber was immersed in warm water at 80 ° C. for 2 days to elute the polyvinyl alcohol resin fine particles to prepare a photocatalyst fiber in which a hollow portion was formed in the laminated supporting portion of the titanium dioxide fine particle fixed glassy spheres.

The prepared 500 photocatalyst fibers were bundled and inserted into a box filled with cigarette smoke for 10 cigarettes, and the air in the box was agitated by a fan for 1 hour while the photocatalyst fine particles-fixed glass spheres of the photocatalyst fibers were stirred. Cigarette smoke was adsorbed on the carrying part. After that, a high-pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide the light, and a photocatalytic reaction was carried out. After 5 hours, the brown crocodile of the tobacco adsorbed on the carrying part and the tobacco odor in the box were completely removed. It was gone.

(Example 5) <Preparation of optical fiber> 10c from the tip of a graded index type quartz optical fiber having a diameter of 1 mm and a length of 60 cm.
The entire surface up to m was scratched with a # 3000 sandpaper to form a light leakage portion. This optical fiber is
-Aminopropyltriethoxysilane 20% by weight was dipped in a solution prepared by hydrolysis and partial condensation in a mixed solution of water and ethanol in a weight ratio of 1: 1 and then pulled up to 6
After drying at 0 ° C. for 5 minutes, the optical fiber light leak part was coated with a partial condensate of γ-aminopropyltriethoxysilane. By this surface treatment, hydroxyl groups and amino groups were formed on the surface of the optical fiber light leak part.

<Preparation of photocatalyst fiber> The glass spheres fixed with photocatalyst particles prepared in Example 4 were floated on the water surface,
After immersing the surface-treated quartz optical fiber in this water, the glass fiber spheres fixed with photocatalyst fine particles are pulled up to a part of the optical fiber light leak part, and heated up at 80 ° C. for 2 hours. Was evaporated and then heated at 250 ° C. for 15 hours to prepare a photocatalytic fiber in which titanium dioxide fine particle-fixed glassy spheres were supported in a single layer on the light leakage part of the quartz optical fiber.

The prepared 500 photocatalyst fibers were bundled and placed in 1 liter of brown water containing 0.7 mmg of cigarette nicotine and 9 mmg of tar, and the high-pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide the light. When a photocatalytic reaction was carried out while stirring the water with a stirrer, the water became colorless and transparent after 17 hours and had no cigarette odor.

(Example 6) <Preparation of photocatalyst fine particle-fixed glassy spheres> In Example 1, hollow glassy spheres were replaced with hollow glassy spheres (Asahi Glass Co., Ltd.).
Cellulase Z-45 manufactured by Manufacturing Co., average particle diameter 52 μm, average shell thickness 0.7 μm) were used, and photocatalyst fine particle fixed glass spheres in which titanium dioxide fine particles were fixed to glassy spheres were prepared in the same manner as in Example 1. did.

<Preparation of Optical Fibers> Step index type polymethylmethacrylate resin having a diameter of 250 μm and a length of 70 cm The entire surface of the optical fibers up to 10 cm from the tip is rubbed with # 1500 sandpaper to scratch and leak light. Formed. This optical fiber was mixed with 10% by weight of γ-glycidoxypropylmethyldimethoxysilane to 1/1.
After dipping in a solution prepared by hydrolysis and partial condensation in a mixed solution of 000N hydrochloric acid and ethanol, and then pulling it up and heating at 60 ° C. for 10 minutes, the optical fiber light leak part is γ-glycidoxypropylmethyldimethoxysilane. Was coated with the partial condensate. By this surface treatment, a hydroxyl group and an epoxy group were formed on the surface of the polymethylmethacrylate resin optical fiber light leak part.

<Production of Photocatalyst Fiber> The above-prepared photocatalyst fine particle-fixed glassy spheres were floated on the partial condensate solution of γ-glycidoxypropylmethyldimethoxysilane obtained in the same manner as above, and the surface treatment was carried out as described above. After immersing the quartz optical fiber in this solution, the glass fiber spheres fixed with photocatalyst fine particles were pulled up in a state in which one layer was adhered to the entire optical fiber light leakage part, and the glass spheres fixed with photocatalyst fine particles were heated for 12 hours at 80 ° C. A photocatalyst fiber in which a single layer was carried on the entire light leakage portion of the methacrylate resin optical fiber was produced.

The prepared 500 photocatalyst fibers were bundled and put in water containing 850 ppm of trichloromethane, and an ultrahigh pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide the light, and the photocatalytic reaction was performed while stirring the water with a stirrer. After 10 hours, the concentration of trichloromethane in water was 19
ppm.

(Example 7) <Preparation of photocatalyst fine particle-fixed glassy spheres> In the same manner as in Example 2 except that the hollow glassy spheres in Example 2 were replaced by solid glassy spheres having a particle diameter of 5 mm. Photocatalyst fine particle fixed glassy spheres were prepared by fixing titanium dioxide fine particles to glassy spheres.

<Preparation of optical fiber> Diameter 10 mm, length 6
A 0 cm step-index type polymethylmethacrylate resin optical fiber was rubbed by rubbing with # 1500 sandpaper over the entire fiber surface up to 10 cm from the tip to form a light leakage part. This optical fiber was immersed in a fluororesin coating material (Lumiflon manufactured by Asahi Glass Co., Ltd.), then pulled up and heated at 80 ° C. for 30 minutes to coat the entire optical fiber light-exposed portion with the fluororesin. The fluororesin coating on the optical fiber leaking part was not completely dried.

<Preparation of Photocatalyst Fiber> The above-prepared photocatalyst fine particle-fixed glassy spheres were placed in a glass dish, and the surface-treated optical fiber was brought into contact with the photocatalyst fine particle-fixed glassy spheres to form a layer on a part of the light leak portion. A glassy sphere fixed with photocatalyst fine particles was attached to the surface. Then, the mixture was heated at 80 ° C. for 30 hours to evaporate the solvent of the fluororesin and to prepare a photocatalyst fiber in which the glassy spheres fixed with photocatalyst fine particles were supported in a single layer on the light leakage part of the polymethylmethacrylate resin optical fiber.

The prepared 500 photocatalyst fibers were bundled and put in water containing 1120 ppm of trichloromethane, and an ultrahigh pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide light.
When a photocatalytic reaction was carried out while stirring the water, the concentration of chloroform in the water became 35 ppm after 10 hours.

(Example 8) <Preparation of photocatalyst fine particle fixed glassy spheres> In Example 1, the hollow glassy spheres were 10% by weight of sodium hydroxide.
Photocatalyst fine particle fixed glassy spheres in which titanium dioxide fine particles were fixed to the glassy spheres in the same manner as in Example 1 except that the glassy spheres were hydrolyzed with an aqueous solution at 80 ° C. for 8 hours to form hydroxyl groups on the surface. Was produced.

<Preparation of optical fiber, preparation of photocatalyst fiber> Except that the above-prepared photocatalyst fine particle fixed glassy spheres were used,
In the same manner as in Example 1, a photocatalyst fiber was produced in which glass spheres fixed with photocatalyst fine particles were laminated and supported on the light leakage part of the quartz optical fiber.

(Example 9) In Example 1, in the preparation of the optical fiber, the surface treatment of the quartz optical fiber light leaking part was performed by immersing it in acetic anhydride, pulling it up, and heating it at 100 ° C to form the surface of the optical fiber light leaking part. A photocatalyst fiber was prepared in the same manner as in Example 1 except that the surface treatment for forming a carboxyl group was replaced with the photocatalyst fine particle-fixed vitreous spheres laminated and supported on the light leakage part of the quartz optical fiber.

The 500 photocatalyst fibers thus prepared were bundled and put in water containing 1200 ppm of dibromochloromethane, and an ultrahigh pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide light, and the photocatalytic reaction was performed while stirring the water with a stirrer. After 8 hours, the concentration of dibromochloromethane in water was 8 ppm.

(Comparative Example 1) In Example 1, the surface-treated quartz optical fiber was dipped in a titanium dioxide sol, pulled up and heated at 500 ° C. A photocatalytic fiber was prepared by directly fixing it. The prepared 500 photocatalyst fibers were bundled and put in water containing 1000 ppm of trichloromethane, and under the same conditions as in Example 1, an ultrahigh pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide light, and the water was stirred with a stirrer. However, when a photocatalytic reaction was carried out, the concentration of trichloromethane in water was only 500 ppm after 6 hours.

(Comparative Example 2) In Example 2, the surface-treated polymethylmethacrylate resin optical fiber was dipped in a titanium dioxide sol, pulled up and heated at 80 ° C. Photocatalytic fibers were prepared by directly fixing titanium fine particles. Chloroform 1500p by bundling 500 prepared photocatalyst fibers
It was placed in water containing pm, and under the same conditions as in Example 1, an ultrahigh pressure mercury lamp was irradiated from the fiber end of the photocatalyst fiber bundle to guide light.
When photocatalytic reaction was carried out while stirring the water with a stirrer, after 9 hours, the concentration of chloroform in the water was 780 pp.
It was only m.

(Embodiment 10) As shown in FIG. 10, the harmful substance removing device comprises a reaction tank 21, a light source 17, a treated water storage tank 25, and a treated water circulating pump 27. Equipped with a top lid 22, diameter 18 cm, height 40 c
The treated water storage tank 25 has a cylindrical shape of m and is a tank made of fluororesin having a capacity of 30 liters. The treated water storage tank 25 and the reaction tank 21, and the reaction tank 21 and the treated water storage tank 25 are They are connected by glass pipes 23, respectively, and the circulation pump 27 feeds the water to be treated into the reaction tank 21.
And Teflon bellows pump model BP-6 manufactured by Freon Industry Co., Ltd.
0 (discharge amount 30 cm ³ / min) was used.

100 photocatalyst fibers 20 produced in Example 1 were fixed to the upper lid 22 of the reaction tank 21, and the photocatalyst fibers 20 were arranged in the reaction tank 21. The fiber end surface exposed on the upper lid 22 was optically polished. Treated water storage tank 25
Water containing 500 ppm of trichloroethane was charged as the treated water 24, and the treated water 24 was circulated by the circulation pump 27. At the same time, Ushio Electric Co., Ltd. was used as the light source 17.
The excitation light 18 from the ultra-high pressure mercury lamp UI-501C manufactured by the manufacturer is reflected by the reflecting mirror 19 to enter from the end of the photocatalyst fiber 20, is emitted from the light leaking part 29 of the base optical fiber 28 of the photocatalyst fiber 20, and is vitreous sphere 30. The photocatalyst fine particles 31 were irradiated with the light to induce a photocatalytic reaction. During the photocatalytic reaction, the reaction vessel 21 was stirred while being rotated by a stirrer. When the device was operated for 9 hours under light irradiation, the trichloroethane concentration in the treated water in water was 8 ppm.

(Embodiment 11) As shown in FIG. 11, the same harmful substance removing apparatus as that used in Embodiment 10 was used. On the upper lid 22 of the reaction tank 21, 500 photocatalyst fibers 20 produced in Example 3 were fixed in a state of being inserted in a glass tube, and the photocatalyst fibers 20 were arranged in the reaction tank 21. Water to be treated 24
Water containing 500 ppm of trichloroethane is used as
The apparatus was operated in the same manner as in Example 10 to cause a photocatalytic reaction. When the device was operated for 10 hours under light irradiation, the trichloroethane concentration in the treated water in water was 1.6 ppm.

(Embodiment 12) As shown in FIG. 12, the harmful substance removing device is provided with a reaction tank 21, a light source 17, and a contaminated air tank 3.
6 and a circulation pump 27, and the reaction tank 21 has an upper lid 2
2 has a cylindrical shape with a diameter of 18 cm and a height of 40 cm, and the contaminated air tank 36 has a vertical length of 60 cm, a horizontal length of 50 cm,
It is a box with a height of 60 cm and contains a contaminated air tank 36 and a reaction tank 2.
1. The reaction tank 21 and the contaminated air tank 35 are made of glass pipe 2
The circulation pump 27 circulates the contaminated air between the reaction tank 21 and the contaminated air tank 36, and an exhaust pump having an exhaust volume of 5 liters / minute was used.

On the upper lid 22 of the reaction vessel 21, 350 photocatalyst fibers 20 produced in Example 4 were bundled and fixed, and the photocatalyst fibers 20 were arranged in the reaction vessel 21. The contaminated air tank 36 was filled with tobacco smoke 33 for 10 cigarettes, and the circulating air 27 was circulated by the circulation pump 27. During the circulation of the cigarette smoke-contaminated air, the cigarette smoke 33 was adsorbed by the photocatalyst fiber 20, and the adsorption site became brown. Then, the light source 17
High pressure mercury lamp manufactured by Oak Manufacturing Co., Ltd. (Model HHM-300
The excitation light 18 from 0) is reflected by the reflecting mirror 19 and is incident from the end of the photocatalyst fiber 20, is emitted from the base optical fiber leaking part of the photocatalyst fiber 20, and is irradiated onto the photocatalyst fine particles through the glassy spheres to irradiate the photocatalyst. The reaction was triggered. During the photocatalytic reaction, cigarette smoke-contaminated air was circulated. When the device was operated for 8 hours under light irradiation, tobacco odor disappeared from the treated air, and the portion where the photocatalyst fiber 20 adsorbed tobacco smoke became colorless.

(Embodiment 13) As shown in FIG. 13, the harmful substance removing device is composed of a reaction tank 21 and a light source 17, and a membrane filtration device 38 is provided in front of the harmful substance removing device. The membrane filtration device 38 is a Mitsubishi Rayon Co., Ltd. in which a polyethylene hollow fiber membrane 39 is housed in a stainless steel housing.
It is composed of a hollow fiber membrane module (model EHF-270TS, membrane area 15 m ² ) and is connected to the reaction tank 21 by a pipe 23. The reaction tank 21 is a stainless steel container having a capacity of 250 liters, and is provided with an upper lid 22.
Then, the photocatalytic fiber 20 produced in Example 6 was fixed, and the photocatalytic fiber 20 was placed in the reaction tank 21.

From the tap 37, total trihalomethane 400
0 ppb, tap water mixed with iron rust is sent, and the membrane filtration device 3
The iron rust was removed by filtration at 8, and filtered water was passed through the reaction tank 21. In addition, the excitation light 18 from the high pressure mercury lamp (model HHM-3000) manufactured by Oak Manufacturing Co., Ltd. used as the light source 17 is reflected by the reflecting mirror 1.
The photocatalytic fiber 20 was reflected by 9 to enter the photocatalytic fiber 20 from the end portion thereof, emitted from the base optical fiber leaking portion of the photocatalytic fiber 20, and irradiated to the photocatalyst fine particles through the glassy sphere to induce the photocatalytic reaction. The water taken out from the reactor outlet 40 had a total trihalomethane concentration of 40 ppb.

(Embodiment 14) As shown in FIG. 14, as in Embodiment 10, the harmful substance removing device is composed of the reaction tank 21 and the light source 17, and the dissolved gas in water is degassed in front of the harmful substance removing device. A device 42 was provided. Underwater dissolved gas deaerator 42
Is a hollow fiber membrane module manufactured by Mitsubishi Rayon Co., Ltd. (model MHF-5104C, membrane area 15) in which the segmented polyurethane hollow fiber membrane 43 for degassing is housed in the housing.
m ² ) and is connected to the reaction tank 21 by a pipe 23. The reaction tank 21 was provided with an upper lid 22, the photocatalyst fiber 20 produced in Example 1 was fixed to the upper lid 22, and the photocatalyst fiber 20 was placed in the reaction tank 21.

The industrial water 41 is fed, degassed by the underwater dissolved gas deaerator 42, and then discharged as degassed industrial water 46, and the membrane permeation gas on the reduced pressure side is passed through the exhaust pump 47 to the reaction tank 21. Passed through. Water vapor, carbon dioxide, oxygen, and 5 ppm of trihalomethane were detected in this membrane permeation gas. Further, the excitation light 18 from the Ushio Electric Co., Ltd. ultra-high pressure mercury lamp UI-501C used as the light source 17 is reflected by the reflecting mirror 19 and is incident from the end portion of the photocatalyst fiber 20, and the base optical fiber light leak part of the photocatalyst fiber 20. And emitted to the photocatalyst fine particles through the glassy sphere to induce the photocatalytic reaction. The purified gas 45 extracted from the reaction tank outlet 40 is
The total trihalomethane concentration was 0.05 ppm.

[0082]

INDUSTRIAL APPLICABILITY The photocatalyst fiber of the present invention has a large adsorption surface area for adsorbing harmful substances, the entire adsorption surface is irradiated with excitation light, and the photocatalytic reaction rapidly progresses. Due to the photocatalytic reaction, trihalomethane in water, bacteria, crabs, etc. Harmful substances such as
It can oxidize and decompose malodorous substances such as tobacco smoke, acetaldehyde and methyl mercaptan in the air. Also,
The harmful substance removing device incorporating the photocatalyst fiber of the present invention can remove the liquid or gas containing the harmful substance as described above even when the flow velocity thereof is high or the concentration of the harmful substance is high. , Water purifier, air purifier, sludge treatment device, sewage treatment device, pool water filtration device, etc.

[Brief description of drawings]

FIG. 1 is a schematic side view of a photocatalyst fiber having only one layer of glass spheres fixed with photocatalyst fine particles supported on all of the optical fiber light leak parts.

FIG. 2 is a schematic side view of a photocatalyst fiber in which only one layer of the glass fiber spheres fixed with photocatalyst particles is carried on a part of the optical fiber light leak part.

FIG. 3 is a schematic side view of a photocatalyst fiber in which photocatalyst fine particle-fixed glassy spheres are laminated and supported on all of the optical fiber light leak parts via an adhesive.

FIG. 4 is a schematic side view of a photocatalyst fiber in which photocatalyst fine particle-fixed glassy spheres are laminated and supported on a part of an optical fiber light leaking portion via an adhesive.

FIG. 5 is a schematic side view of a photocatalyst fiber in which photocatalyst fine particle-fixed glass spheres are laminated and supported on all of the optical fiber light leaking portions with an adhesive, and a hollow portion is formed in the supporting portion.

FIG. 6 is a schematic side view of a photocatalyst fiber in which photocatalyst fine particle-fixed glassy spheres are laminated and supported on a part of an optical fiber light leaking portion with an adhesive, and a hollow portion is formed in the supporting portion.

FIG. 7 is a schematic diagram of an example of a harmful substance removing device of the present invention.

FIG. 8 is a schematic diagram of another example of the harmful substance removing apparatus of the present invention.

FIG. 9 is a schematic diagram of another example of the harmful substance removing apparatus of the present invention.

FIG. 10 is a schematic diagram of a harmful substance removing device used in Example 10.

FIG. 11 is a schematic diagram of a harmful substance removing apparatus used in Example 11.

FIG. 12 is a schematic diagram of a harmful substance removing apparatus used in Example 12.

FIG. 13 is a schematic diagram of a harmful substance removing device used in Example 13.

FIG. 14 is a schematic diagram of a harmful substance removing apparatus used in Example 14.

[Explanation of symbols]

 1 Optical Fiber Leakage Part 2 Vitreous Sphere 3 Photocatalyst Fine Particles 4 Optically Transparent Adhesive 5 Cavity Part 6 Light Source 7 Excitation Light 8 Reflecting Mirror 9 Photocatalytic Fiber 10 Reaction Tank 11 Top Lid 12 Treated Material Inlet 13 Light Leakage 14 Vitreous Sphere 15 Photocatalyst fine particle 16 Treated product outlet 17 Light source 18 Excitation light 19 Reflector 20 Photocatalyst fiber 21 Reaction tank 22 Upper lid 23 Piping 24 Treated water 25 Treated water storage tank 26 Treated water for partial treatment 27 Circulation pump 28 Optical Fiber 29 Light-leaking part 30 Vitreous sphere 31 Photocatalyst fine particle 32 Optically transparent adhesive 33 Cigarette smoke 34 Tobacco 35 Ashtray 36 Contaminated air tank 37 Water faucet 38 Membrane filter 39 Hollow fiber membrane 40 Reaction tank outlet 41 Industrial water 42 Desorption Air device 43 Degassing hollow fiber membrane 44 Membrane permeation gas 45 Purification gas 46 Degassing industrial water 47 Exhaust pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C02F 1/72 101 B01D 53/36 ZABG

Claims (6)

[Claims] 1. A photocatalyst fiber, characterized in that glassy spheres having photocatalyst fine particles fixed to the surface thereof are carried on at least a part of the surface of an optical fiber having a light leak portion. 2. A photocatalyst fiber, characterized in that glassy spheres having photocatalyst fine particles fixed to the surface thereof are carried on at least a part of the surface of an optical fiber having a light leak part through an optically transparent adhesive. 3. The photocatalyst fiber according to claim 1 or 2, wherein the glassy spheres are supported on at least the light leakage part on the surface of the optical fiber. 4. The glassy sphere is a hollow sphere,
The photocatalyst fiber according to claim 2 or 3. 5. The photocatalyst fiber according to claim 1, claim 2, claim 3, or claim 4, wherein a hollow portion is formed in a supporting portion through which the adhesive is interposed. 6. A harmful substance removing device, wherein the photocatalytic fiber according to claim 1, claim 2, claim 3, claim 4, or claim 5 is incorporated in a photocatalytic reaction tank for harmful substances.