JP2006136874A - Circulation type sewage purification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sewage purification method using sunlight, which can maximally use photocatalytic reactions, is simple and low cost, and does not require a wide space. <P>SOLUTION: In the circulation type sewage purification method, sewage is supplied to the upper end of a tabular photocatalyst-carrying porous body disposed so as to receive sunlight in a state declined at an angle (θ) of ≥10° to the ground, the sewage is dropped from a dropping port installed at the upper end of the porous body at a flow rate of K(1-cosθ) per one dropping port (K is the maximum value of water feed rate per one dropping port when dropping the sewage from the upper end of the dropping port in a state vertically erecting the porous body) and recovered from the lower end of the porous body, and the recovered sewage is supplied to the upper end of the porous body repeatedly. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a circulating sewage purification method. More specifically, the present invention relates to a circulating sewage purification method that uses a flat photocatalyst-supported porous body and effectively purifies various sewage, for example, agricultural chemical effluents and waste liquids in hydroponics, using sunlight. It is about.

When a photocatalytic material (hereinafter sometimes simply referred to as a photocatalyst) is irradiated with light having energy higher than its band gap, it is excited to generate electrons in the conduction band and holes in the valence band. The generated electrons reduce surface oxygen to generate superoxide anions (• O ²⁻ ), and holes oxidize surface hydroxyl groups to generate hydroxyl radicals (• OH). It is known that active oxygen species exert a strong oxidative decomposition function and decompose organic substances adhering to the surface of the photocatalyst with high efficiency.
By applying such photocatalytic functions, for example, deodorization, antifouling, antibacterial, sterilization, and decomposition / removal of various substances that cause environmental pollution in wastewater and waste gas are being studied. Yes.

  Further, as another function of the photocatalyst, it is also known that when the photocatalyst is photoexcited, the surface of the photocatalyst develops superhydrophilicity with a contact angle with water of 10 degrees or less (for example, Patent Documents). 1). Applying such a superhydrophilic function of the photocatalyst, for example, for preventing pollution caused by soot contained in the exhaust gas of an automobile for a soundproof wall of a highway, lighting in a tunnel, street light, etc., or for an automobile body coat or side The use of photocatalysts for mirror films, antifogging and self-cleaning window glass has been studied.

  As such photocatalysts, compounds having various semiconductor characteristics such as metal oxides such as titanium dioxide, iron oxide, tungsten oxide and zinc oxide, and metal sulfides such as cadmium sulfide and zinc sulfide have been known. However, among these, titanium dioxide, particularly anatase titanium dioxide, is useful as a practical photocatalyst. This titanium dioxide exhibits excellent photocatalytic activity by absorbing light of a specific wavelength in the ultraviolet region contained in daily light such as sunlight.

  As one of the uses of the photocatalyst, as described above, it has been attempted to decompose and remove various substances that are a problem of environmental pollution in wastewater, and is made of, for example, a heat-resistant fiber having light permeability. There has been proposed a technique for treating harmful substances in a liquid using a photocatalyst formed by forming a titanium oxide film on a heat-resistant fiber itself of a woven fabric (see, for example, Patent Document 2). In addition, using a titanium oxide photocatalyst and utilizing sunlight, a technique for treating the waste liquid after paddy rice seed disinfection (see, for example, Patent Document 3), and the waste liquid in culture medium circulation type hydroponic cultivation using an organic medium Processing techniques (see, for example, Patent Documents 3 and 4) have been proposed.

  However, it is generally difficult to efficiently decompose organic substances remaining in an aqueous solution using such a photocatalytic reaction. The decomposition reaction occurs when the wastewater to be treated is brought into contact with the photocatalyst body and irradiated with ultraviolet light. In this case, the factor that determines the decomposition reaction is not the photocatalytic reaction, but the transport of the substance to be decomposed to the photocatalyst body. Often in the process and adsorption process.

  In addition, as a phenomenon that occurs on the surface of the photocatalyst, only an oxidation reaction that decomposes an organic substance is attracting attention, but a reduction reaction is also occurring at the same time. These two reactions are paired, and it is known that the reaction rate decreases when one of the reactions is delayed. In particular, a reduction reaction having only weak reducing power may cause both reactions to stagnate. In the oxidative decomposition of gas phase molecules, oxygen in the air plays the role of a sacrificial reducing agent, but in the reaction in water, it depends on a very small amount of dissolved oxygen, and the activity is significantly reduced.

In addition, the photocatalyst material is often used by supporting it on a transparent structure having a large surface area, but when such a structure is irradiated with light, the amount of light scattered increases due to the large surface area. As a result, regardless of the transparency of the material itself, there is a problem that ultraviolet light does not penetrate into the structure and the activity corresponding to the amount of photocatalyst is not exhibited.
As described above, various proposals have been made for sewage purification technology using photocatalytic reaction. However, sewage purification technology that can fully utilize the photocatalytic reaction in consideration of all the above-mentioned viewpoints has been proposed so far. It didn't exist and was real.

International Patent Publication No. 96/29375 JP-A-7-96202 JP 2004-82095 A Japanese Patent Laid-Open No. 9-327246

  Under such circumstances, the present invention uses a structure capable of penetrating ultraviolet light to the inside, and has good transport / adsorption efficiency of the substance to be decomposed to the photocatalyst carrier, and also efficiently in water. It is possible to promote the sacrificial reduction of water, to make the most of photocatalytic reaction, and to provide an effective sewage purification method using sunlight, which is simple and inexpensive, does not require a large space. It is intended to provide.

  As a result of intensive research to achieve the above object, the present inventors have used a flat photocatalyst-supported porous body having a specific property, and in particular, the sun is tilted at an angle of a certain value or more with respect to the ground. Installed so that light hits uniformly, from the plurality of dripping ports provided at the upper end portion, to-be-treated sewage is dropped at a dripping flow rate of a certain value or less per one dripping port, and recovered from the lower end surface of the photocatalyst-supporting porous body. The inventors have found that the object can be achieved by the circulation type purification method supplied again to the upper end of the porous body, and have completed the present invention based on this finding.

That is, the present invention
(1) To-be-processed sewage is supplied to the upper end part of the flat photocatalyst carrying porous body installed so that sunlight may hit in the state inclined at 10 degrees or more with respect to the ground, From a plurality of dripping ports provided in the width direction at the upper end, per dripping port, the formula (I)

_{F R ≦ K (1-cosθ} ) ... (I)

[ _Wherein FR is the dropping flow rate per dropping port of the treated sewage, θ is the angle of the photocatalyst-carrying porous body with respect to the ground, and K is the photocatalyst-carrying porous body standing vertically and from the dripping port provided at the upper end thereof. When the sewage to be treated is supplied, the maximum value of the water supply speed per dropping port is shown. ]
Recycling sewage dropwise at a satisfy the relationship flow rate F _R, after passed through the photocatalyst carrying porous body was recovered from the bottom end face, characterized in that it repeatedly supplied to the upper part of the photocatalyst-carrying porous body Purification method,
(2) The circulating sewage purification method according to (1), wherein the plurality of dripping ports are provided at intervals of 3 to 10 cm,
(3) An inorganic porous body in which the plate-like photocatalyst-supported porous body includes a woven or non-woven fabric made of porous ceramics or inorganic fibers, has a water retention of 500 to 3000 mass%, and a suction height of 12 mm or more. Of the photocatalyst material and an inorganic adhesive component and / or an adsorbent on the surface that is exposed to sunlight, and a volume fraction of the photocatalyst material in the coat is 30 to 90%. support amount 8 to 20 g / m 2 ^of, and the water contact angle of the coating film provided on the smooth surface is 60 ° or less, thickness and has a flat plate shape than 12mm above (1) or ( (2) The circulating sewage purification method according to item 2)
(4) The circulating sewage purification method according to item (3), wherein the inorganic adhesive component is an amorphous type titania binder,
(5) The adsorbent and / or the inorganic adhesive component has a solid basicity with an isoelectric point of pH 9.0 or more, and selectively decomposes and removes acidic sewage components (3) or ( 4) the circulating sewage purification method according to item 4),
(6) Adsorbent and / or inorganic adhesive component has a solid basicity with an isoelectric point of pH 9.0 or higher, and selectively decomposes hydrophobic sewage components emulsified with a surfactant. The circulating sewage purification method according to (3) or (4) above,
(7) The adsorbent is alumina having an average particle diameter of 100 nm or less and a crystal form of boehmite, and the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body is 10 to 45%. The circulating sewage purification method according to (5) or (6),
(8) The adsorbent and / or the inorganic adhesive component has a solid acidity having an isoelectric point of pH of 3.0 or less, and selectively decomposes and removes the basic sewage component (3) or ( 4) the circulating sewage purification method according to item 4),
(9) The water contact angle of the coating film provided on the smooth surface is 40 to 60 °, and any one of the above items (1) to (4), which selectively decomposes and removes hydrophobic sewage components Circulating sewage purification method according to item,
(10) The adsorbent that adsorbs hydrophobic sewage components is activated carbon, and the activated carbon has a ratio of the sum of the volumes of pores having a pore diameter of 10 nm or more of 19% or more of the total pore volume, The circulating sewage purification method according to (9), wherein the average particle diameter is 10 μm or less, and the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body is 5 to 60%. And (11) a woven fabric having a strength of 98 N / cm or more, comprising a flat photocatalyst-carrying porous body having a thickness of less than 12 mm, made of inorganic fibers or organic fibers on the opposite side of the photocatalyst-carrying porous body from the side on which sunlight strikes. The circulating sewage purification method according to any one of the above (3) to (10), which is used as a two-layer structure,
Is to provide.

  According to the present invention, a plate-like photocatalyst-supported porous body that allows ultraviolet light to penetrate to the inside is used, and the efficiency of transporting and adsorbing a substance to be decomposed to the photocatalyst-supported porous body is good, and oxygen is sacrificed efficiently even in water. An effective circulation-type sewage purification method using sunlight, which is capable of maximizing the use of photocatalytic reactions, is simple and inexpensive, does not require a large space, Can be provided.

The circulating sewage purification method of the present invention is a method of purifying sewage by photocatalytic reaction using sunlight using a photocatalyst-supporting porous body, and at that time, utilizing the photocatalytic reaction to the maximum, In order to effectively decompose and remove the material to be treated, the following is performed.
In the photocatalyst-supporting porous material used in the present invention, it is important to set a flow path so that sewage can reach inside, and to set a flow path so that ultraviolet light and air can easily reach the inside.

  Therefore, in the present invention, a plurality of treated sewage dripping openings are provided in the width direction at the upper end of the photocatalyst-supporting porous body (hereinafter sometimes simply referred to as a photocatalyst), and this is 10 ° or more with respect to the ground. Installed so that the sunlight hits uniformly while tilted at an angle of. And the to-be-processed sewage is dripped at the predetermined | prescribed flow velocity from the some dripping port provided in the upper end part of the said photocatalyst body, and the said photocatalyst body is made to soak. The soaked sewage passes through the inside of the photocatalyst by its own weight, and the sewage purified by the photocatalytic reaction is drained from the lower end face of the photocatalyst.

  In the sewage purification method of the present invention, the treated sewage can be uniformly infiltrated into the photocatalyst body by providing a plurality of treated sewage dripping ports in the width direction at the upper end of the photocatalyst body.

  In addition, by installing the photocatalyst body at an angle of 10 ° or more with respect to the ground, it is possible to ensure a practical supply rate of treated wastewater, and as a sacrificial reducing agent in the air Oxygen can be used effectively. Considering the supply rate of the wastewater to be treated and the use of oxygen in the air as a sacrificial reducing agent, the angle of the photocatalyst with respect to the ground is preferably 45 ° or more, particularly preferably 60 ° or more.

  In the sewage purification method of the present invention, it is important to control the supply rate of the sewage to be treated so that the photocatalyst is not completely submerged and moistened. Therefore, in the present invention, from a plurality of dropping ports provided at the upper end portion of the photocatalyst body, per one dropping port, the formula (I)

_{F R ≦ K (1-cosθ} ) ... (I)

[ _Wherein FR is the dropping flow rate per dropping port of the treated sewage, θ is the angle of the photocatalyst-carrying porous body with respect to the ground, and K is the photocatalyst-carrying porous body standing vertically and from the dripping port provided at the upper end thereof. When the sewage to be treated is supplied, the maximum value of the water supply speed per dropping port is shown. Added dropwise treated wastewater at a flow rate F _R that satisfies the relationship.

By this control, the photocatalyst body can easily take in oxygen in the air, and as a result, the sacrificial reduction of oxygen can be promoted and the photocatalytic activity can hardly be reduced. The dropping velocity _{F R} from practical aspects, K (1-cosθ) is preferably in the range of × (0.1~1.0), K (1 -cosθ) × (0.3~0.7) The range of is particularly preferable.

The K value can be obtained as follows. The photocatalyst is placed in a state of θ = 90 °, the treated sewage is dropped at a dropping speed F _R = 1.0 ml / min, and the change in the concentration of the discharged solution with respect to the volume of the dropped liquid is measured. Then by repeating the same measurement while increasing stepwise addition rate _{F R,} in _{F R} ≧ _K, not to reproduce the density change in the conditions of F R = 1.0ml / min. Thus, K can be obtained experimentally.

The dripping speed of the wastewater to be treated is, for example, from a method of providing a valve at the dripping port, a method of feeding water by controlling the flow rate to a perforated water pipe, a porous tube having countless micropores by controlling pressure and flow rate, etc. It can be controlled by a method of exuding treated sewage, etc., and by such a method, the treated sewage can be supplied at a constant flow rate across the entire width of the upper end portion of the photocatalyst-supporting porous body. Is possible. When using a method of providing a valve at the dropping port or a method of feeding water by controlling the flow rate to a perforated water pipe, the interval between the dropping ports is preferably 3 to 10 cm, more preferably 3 to 5 cm. preferable.
The sewage that passes through the photocatalyst and is purified by the photocatalytic reaction is collected from the lower end surface of the photocatalyst and is repeatedly supplied to the upper end of the photocatalyst. This circulation operation is performed until the content of the substance to be decomposed / removed in the sewage reaches a desired value.

In the sewage purification method of the present invention, by using a photocatalyst-supporting porous body (photocatalyst body) having the following properties, a substance to be treated in sewage can be effectively decomposed and removed.
The photocatalyst is a flat plate, and a coating film (hereinafter referred to as a photocatalyst layer) containing a photocatalyst material and an inorganic adhesive component and / or an adsorbent on the surface of the inorganic porous body that is exposed to sunlight. There is a structure provided.

  It is preferable that the said inorganic porous body has a space | gap so that the water retention rate of distilled water may be 500-3000 mass%. If the water retention rate is in the above range, the surface area in contact with the sewage is sufficiently large, the sewage easily passes through the inside of the inorganic porous body, and the ultraviolet light sufficiently reaches the inside of the inorganic porous body. A more preferable water retention rate is 500-1500 mass%.

Moreover, it is preferable that the suction height (capillary force) of distilled water is 12 mm or more. If this suction height is 12 mm or more, the treated sewage easily penetrates into the photocatalyst body. The suction height is more preferably 50 mm or more. Although there is no restriction | limiting in particular in the upper limit of this wicking height, Usually, it is about 200 mm.
The method for measuring the water retention rate and suction height of the distilled water will be described later.

  As a material constituting such an inorganic porous body, it can be appropriately selected from porous ceramics having a three-dimensional network structure, woven fabrics and nonwoven fabrics made of inorganic fibers, from an economic viewpoint, A woven fabric or a nonwoven fabric made of glass fiber is suitable. Examples of the woven fabric and nonwoven fabric made of glass fiber include silica glass long fiber woven fabric woven by a general method, silica glass short fiber entangled nonwoven fabric produced by a needle punch method, and the like.

In the photocatalyst body, a coating film (photocatalyst layer) including a photocatalyst material and an inorganic adhesive component and / or an adsorbent is provided on the surface of the inorganic porous body. The volume fraction of the photocatalytic material in the coating film is preferably in the range of 30 to 90%. If this volume fraction is in the above range, it has a good photocatalytic activity and the substance to be treated in the sewage is easily trapped in the vicinity of the photocatalytic material. The volume fraction is more preferably 30 to 70%.
In addition, the amount of the photocatalytic material supported is preferably in the range of 8 to ²⁰ g / m ² , and more preferably in the range of 10 to 15 g / m ² , regardless of the amount of adsorbent, from the viewpoint of the balance of photocatalytic activity and economy. preferable.
Further, the surface wettability of the photocatalyst is preferably 60 ° or less in terms of the water contact angle of the coating film provided on a smooth surface such as a slide glass. If the water contact angle is 60 ° or less, the sewage is likely to penetrate into the photocatalyst body.

The thickness of the flat photocatalyst is preferably less than 12 mm. If this thickness is less than 12 mm, the ultraviolet light easily reaches the deep part of the photocatalyst. The minimum thickness may be a thickness with which the transmittance of light at 365 nm is 20% or less, although it depends on the structure of the inorganic porous material.
As a photocatalyst material constituting the coating film (photocatalyst layer) in the photocatalyst body, for example, anatase type titanium oxide and / or brookite type titanium oxide can be used, and an anatase type having an average particle size of 1.0 to 100 nm. Titanium oxide fine particles are preferable, and those having an average particle diameter of 1.0 to 50 nm are particularly preferable. The average particle diameter can be measured by a scattering method using laser light.

  Further, at least one selected from the group consisting of V, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Pt and Au as a second component inside and / or on the surface of the titanium oxide particles. It is preferable to include a seed metal and / or metal compound because it has a higher photocatalytic function. Examples of the metal compound include metal oxides, hydroxides, oxyhydroxides, sulfates, halides, nitrates, and metal ions. The content of the second component is appropriately selected according to the type of the substance.

  The anatase-type titanium oxide particles can be produced by a conventionally known method, but it is advantageous to use the titanium oxide sol in the form of a titanium oxide sol in order to uniformly disperse it in the coating liquid. In order to produce the titanium oxide sol, for example, powdered anatase-type titanium oxide may be dissolved in the presence of acid or alkali, or the particle diameter may be controlled by pulverization. In addition, the hydrous or neutralized decomposition of titanium sulfate or titanium chloride may be used to control the crystallite size and particle size by physical and chemical methods. Furthermore, a dispersion stabilizer can be used to impart dispersion stability in the sol solution.

  Moreover, as an adsorbent which comprises the coating film (photocatalyst layer) in the said photocatalyst body, colloidal silica, an alumina, a zirconia, an amorphous titania, magnesium hydroxide, activated carbon etc. can be used, for example. These may be used individually by 1 type and may be used in combination of 2 or more type.

Furthermore, as an inorganic adhesive component which comprises the coating film (photocatalyst layer) in the said photocatalyst body, a silica binder, an alumina binder, an amorphous type titania binder etc. can be used, for example. These may be used alone or in combination of two or more. Among them, an amorphous titania binder is preferable because of its excellent water resistance.
This amorphous titania binder can be produced by hydrolysis and condensation of titanium alkoxide.

  As the titanium alkoxide, titanium tetraalkoxide having 1 to 4 carbon atoms in the alkoxyl group is preferably used. In this titanium tetraalkoxide, the four alkoxyl groups may be the same or different, but the same one is preferably used from the viewpoint of availability. Examples of the titanium tetraalkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetraisopropoxide, titanium tetra-n-butoxide, titanium tetraisobutoxide, titanium tetra-sec- Examples include butoxide and titanium tetra-tert-butoxide. These may be used individually by 1 type and may be used in combination of 2 or more type.

The titanium alkoxide is hydrolyzed / condensed to form an amorphous type titania binder. This hydrolysis / condensation reaction is preferably 0.5 to 4 times that of titanium tetraalkoxide in an appropriate organic solvent. The reaction can be carried out at a temperature of usually 0 to 70 ° C., preferably 20 to 50 ° C. in the presence of an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, etc.
In this way, an amorphous titania binder having excellent water resistance is obtained.

In the present invention, to produce a photocatalyst-supporting porous body (photocatalyst body), first, a photocatalyst coating solution is prepared. This photocatalyst coating solution can be prepared by dispersing the photocatalyst material and an adsorbent and / or an inorganic adhesive component in an appropriate solvent.
The photocatalyst coating liquid thus obtained is applied to at least the surface of the inorganic porous body that is exposed to sunlight, and a coating film (photocatalyst layer) is provided, whereby a flat photocatalyst having a thickness of less than 12 mm is provided. A supported porous body (photocatalyst body) can be produced.
Although there is no restriction | limiting in particular about the coating method of a photocatalyst coating liquid, For example, the immersion method etc. can be used.

  In the present invention, the flat photocatalyst-supported porous body having a thickness of less than 12 mm is a woven fabric having a strength of 98 N / cm or more made of inorganic fibers or organic fibers on the opposite side of the photocatalyst-supported porous body from the side on which sunlight strikes. Can be used as a two-layer structure. By adopting the two-layer structure in this way, the strength of the photocatalyst-supporting porous body can be dramatically improved while maintaining the purification efficiency of sewage.

In the sewage purification method of the present invention, an acidic sewage component is selectively used by using an adsorbent and / or an inorganic adhesive component having solid basicity with an isoelectric point of pH 9.0 or more. It can be decomposed and removed, and hydrophobic sewage components emulsified with a surfactant can be selectively decomposed and removed.
Further, by using an adsorbent and / or an inorganic adhesive component having a solid acidity with an isoelectric point of pH of 3.0 or less, basic sewage components can be selectively decomposed and removed. .

  Examples of the solid basic adsorbent include alumina and magnesium hydroxide, and examples of the solid basic inorganic adhesive component include an alumina binder. On the other hand, examples of the solid acidic adsorbent include colloidal silica, and examples of the solid acidic inorganic adhesive component include a silica binder.

  When using alumina as the solid basic adsorbent, it is preferable to use a boehmite-like crystal having an average particle size of 100 nm or less, and the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body. Is preferably 10 to 45%.

Since active radicals move about several microns in water, the photocatalytic material and the adsorbent must be uniformly dispersed within a few microns or less, but in the case of alumina, secondary agglomeration is a concern. In order for the size of the aggregate to be several microns or less, the average primary particle size must be 100 nm or less. The lower limit of the average particle diameter is not particularly limited, but 10 nm or less is technically and economically difficult. The average particle diameter of alumina is more preferably 30 to 90 nm.

Further, the volume fraction of the adsorbing component in the coating film provided on the surface of the inorganic porous body is preferably 10 to 45%, but the coating film depends on the state of the treated sewage containing acidic sewage components. Optimum sewage purification treatment can be carried out by appropriately adjusting the volume fraction of the alumina inside. That is, when the sewage component is mainly acidic, the volume fraction of the adsorbed component in the coating film provided on the surface of the inorganic porous body is preferably 10 to 21%, more preferably 12 to 18%. By making it, wastewater components can be efficiently decomposed and removed. The state of decomposition and removal of sewage components can be confirmed by whether or not the decomposition rate constant is a predetermined value or more. This decomposition rate constant is a representative example of benzoic acids contained in trace amounts in industrial waste liquids, for example. When benzoic acid is used, it is obtained by multiplying the slope (ppm / h) of change in concentration of benzoic acid by 30 to 60 hours after the start of the circulation test in which the initial adsorption has been completed by -10. it can. Specifically, 20 ppm of benzoic acid as an acidic sewage component is contained in 200 L of industrial waste liquid, and when this is decomposed and removed in one week under a light amount condition of ² mW / m ² , the decomposition rate constant is 70 The decomposition rate constant is determined, for example, by measuring a concentration of each decomposition object by collecting a small amount of circulating fluid after 30 hours and 60 hours after the start of the test. It can be obtained by an expression.

On the other hand, when the sewage component is mainly an organic substance other than acidic and a small amount of acidic sewage component coexists, the volume fraction of alumina in the coating film is preferably 21 to 45%, more preferably 25. By setting it to -40%, acidic sewage components can be adsorbed, decomposed and removed efficiently.
Usually, when organic substances other than acidic sewage components increase as sewage components, there is a concern that the rate at which the decomposition target is decomposed significantly decreases. However, by setting the volume fraction of alumina to the above-mentioned value, the decomposition target (acid sewage component) can be selectively decomposed and removed without depending on the amount of organic substances other than the target substance in the sewage. Can do.

The decomposition and removal state of the acidic sewage component can be confirmed by whether or not the decomposition rate constant is a predetermined value or more. For example, when the acidic sewage component is benzoic acid, It can be obtained by the same method as described above.
In this case, for example, if the benzoic acid in the industrial waste liquid is decomposed / removed under the same conditions as described above, the content of benzoic acid is relatively low, and the benzoic acid is treated as it is without pretreatment such as fractionation. As a result, there is a comparative margin in time constraints for decomposing and removing benzoic acids. For this reason, the lower limit value of the decomposition rate constant can be set lower than when the sewage component is mainly acidic. For example, the total organic carbon amount in the industrial waste liquid is 200, 400, 600, 800 (mg / L), when benzoic acid is used, the decomposition rate constant should be 55 (ppm / h) or more.

  Furthermore, by using a photocatalyst having a water contact angle of 40 to 60 ° when the coating film is provided on a smooth surface such as a glass slide, a hydrophobic sewage component is selectively used. It can be disassembled and removed.

  When treating sewage containing a hydrophobic sewage component, activated carbon can be used as an adsorbent. Conventionally, when using activated carbon, the one having a pore size as small as possible and a large surface area has been used, but in the present invention, contrary to the conventional method, the pore size is large and the coating solution is And those having an average particle size that does not cause precipitation are preferably used. As such activated carbon, the sum of the volumes of pores having a pore diameter of 10 nm or more is 19% or more of the total pore volume ((sum of volumes of pores having a pore diameter of 10 nm or more / total Pore volume) × 100 is 19% or more) and the average particle diameter is 10 μm or less. Moreover, it is preferable that the upper limit of the ratio of the total volume of pores having a pore diameter of 10 nm or more to the total pore volume is about 50%. This is because, when the ratio of those having a large pore diameter increases, it contributes to wettability in water, but the surface area decreases and activated carbon loses its original adsorption ability. Further, although there is no particular lower limit to the average particle diameter, it is difficult technically and economically if it is 1 μm or less.

As described above, since active radicals move several microns in water, it is necessary to uniformly disperse the photocatalyst and the adsorbent within a range of several microns or less. In the case of activated carbon, the size is already a few microns, so the activated carbon in the coating solution must be almost monodispersed, but the particle wettability is strictly controlled to ensure monodispersity. Therefore, the size of the pore diameter is greatly limited as described above.
Since the dispersibility of the activated carbon is greatly improved by using the activated carbon, in the photocatalyst of the present invention, it is difficult to inhibit the photocatalytic activity, and the volume fraction of the activated carbon in the coating film (photocatalyst layer) is up to 75%. Can maintain the complete degradability of the sewage component by the photocatalyst. In the activated carbon, the ratio of the sum of the volumes of pores having a pore diameter of 10 nm or more is more preferably 20% or more of the total pore volume.

When activated carbon is used as the adsorbent, the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body is preferably 5 to 60%. Optimal sewage purification treatment can be performed by appropriately adjusting the volume fraction of the activated carbon in the coating film according to the state of the treated sewage. That is, when the sewage component is mainly hydrophobic, the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body is preferably 5-35%, more preferably 10-25. By setting the ratio to%, the sewage components can be efficiently decomposed and removed. The state of decomposition and removal of the sewage component can be confirmed by whether or not the decomposition rate constant is a predetermined value or more. For example, when the sewage component is ipconazole, the initial adsorption of ipconazole Can be obtained by multiplying the slope (ppm / h) of change in ipconazole concentration in 30 to 60 hours after the start of the circulation test by -10. Specifically, 20 ppm of ipconazole is contained as a hydrophobic sewage component in 200 L of agricultural waste liquid, and when this is decomposed and removed in one week under a light amount condition of ² mW / m ² , the decomposition rate constant is 70. The decomposition rate constant is determined, for example, by measuring a concentration of each decomposition object by collecting a small amount of circulating fluid after 30 hours and 60 hours after the start of the test. It can be obtained by an expression.

On the other hand, when the sewage component is mainly a hydrophilic organic substance and a small amount of hydrophobic sewage component coexists, the volume fraction of activated carbon in the coating film is preferably 35 to 60%, more preferably By adjusting the content to 40 to 50%, hydrophobic sewage components can be efficiently adsorbed, decomposed and removed.

In general, when the amount of hydrophilic organic substances other than the hydrophobic sewage component increases as the sewage component, there is a concern that the rate of decomposing the decomposition target object is significantly reduced. However, by setting the solid content concentration of the activated carbon to the above-mentioned concentration, the decomposition target (hydrophobic sewage component) can be selectively decomposed and removed without depending on the abundance of the hydrophilic organic matter in the sewage. .
The decomposition and removal state of the hydrophobic sewage component can be confirmed by whether or not the decomposition rate constant is a predetermined value or more. For example, when the hydrophobic sewage component is ipconazole, It can be determined by the same method as described above.

In this case, for example, if it is attempted to decompose and remove ipconazole in the agricultural waste liquid under the same conditions as described above, the content of ipconazole is relatively small, and it can be directly processed without pretreatment such as fractionation. Therefore, there is a comparative margin in time constraints for decomposing and removing ipconazole. For this reason, compared with the case where a sewage component is mainly hydrophobic, the lower limit of a decomposition rate constant can be set low, for example, the total amount of organic carbon in agricultural waste liquid is 200, 400, 600, 800 ( In all the samples of mg / L), the ipconazole decomposition rate constant may be 55 (ppm / h) or more.

  The contact angle of the coating film varies depending on the type of adsorbent and binder used. Therefore, in order to control the water contact angle of the coating film provided on the smooth surface to 40 to 60 °, hydrophobic colloidal silica is used as an adsorbent and titania binder is used as an inorganic adhesive component when preparing the coating liquid. It is good to use. Since the mixing ratio varies depending on the type of the adsorbent and the adhesive component, the water contact angle may be confirmed by forming a film on, for example, a slide glass using the prepared coating liquid.

FIG. 1 is a basic layout diagram in the circulating sewage purification method of the present invention. As shown in FIG. 1, in the sewage purification method of the present invention, the optical axis and the flow axis are in a vertical relationship, and the photocatalyst is not completely submerged and wetted (result). It is easy to take in oxygen in the air). Further, in order to use sunlight as a light source, the photocatalyst is preferably flat so that light uniformly strikes the photocatalyst, but may have a slightly curved structure.
The wastewater flowing into the photocatalyst body uses gravity, and the treated water discharged from the lower end surface of the photocatalyst body circulates to the upper end portion of the photocatalyst body.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, each characteristic was measured in accordance with the method shown below.

(1) Water contact angle of the coating film on a smooth surface A coating liquid is applied to the surface of the slide glass to form a coating film having a thickness of 100 to 300 nm, and the water contact angle under conditions of a temperature of 25 ° C. and a humidity of 50%. The water contact angle was measured using a measuring instrument “G-1-1000” (Elma Sales Co., Ltd.).

(2) Amount of supported photocatalytic material It was calculated from the amount of increase in the inorganic porous material mass before and after coating and the mass ratio of the photocatalytic material contained in the solid content of the coating liquid.

(3) Volume fraction in the coating film of the photocatalytic material The ratio of the volume of the photocatalytic material to the total volume of each component contained in the solid content of the coating liquid obtained from the mass and density was calculated.

(4) Concentration of solution containing component to be treated For the sample solution (methylene blue), the absorbance of light at 660 nm was measured, and the concentration of the solution to be treated in the sample solution was determined based on the calibration curve showing the concentration-absorbance relationship prepared in advance. The concentration of the component was determined.
The sample solution (benzoic acid) is analyzed by a chromatographic method, and the concentration of the component to be treated in the sample solution is determined from the corresponding peak area and a calibration curve indicating the relationship between the concentration and the peak area prepared in advance. Asked.
The sample solution (ipconazole) was analyzed by reversed layer liquid chromatography, and the corresponding peak area was determined in advance from the calibration curve showing the relationship between the concentration and the peak area. The concentration was determined.
The total organic carbon amount (TOC) was measured using a total organic carbon meter “TOC-5000” (Shimadzu Corporation).

(5) Average particle diameter of alumina It measured with the laser zeta electrometer "ELS-8000" (Otsuka Electronics Co., Ltd.).

(6) Pore diameter and pore volume ratio of activated carbon Measurement was performed with a high-precision specific surface area / pore distribution measuring apparatus “BELSORP28SA” (Nippon Bell Co., Ltd.).

(7) Average particle diameter of activated carbon It measured with the laser diffraction type particle size distribution measuring apparatus "SALD-3000J" (Shimadzu Corporation).

Example 1
(1) Preparation of photocatalyst coating solution Photocatalyst coating solution containing photocatalytic titanium oxide (anatase type titanium oxide, average particle size 20 nm) and silica binder which is a solid acidic inorganic adhesive component [manufactured by Titanium Industry Co., Ltd., “PC- 401 ”, solid content 20 mass% (titania / silica = 4/6, mass ratio)] 12 g, and photocatalytic titanium oxide (anatase type titanium oxide, average particle size 20 nm) slurry [made by Titanium Industry Co., Ltd.,“ PC- 203 ", 20 mass% solid content] 17 g was mixed with 472 g of water to prepare a coating solution.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 30 °.
(2) Production of photocatalyst-supporting porous body As an inorganic porous body, a flat plate shape having a water retention rate of 1000 mass%, a suction height of 100 mm, a thickness of 6 mm, and a basis weight of 700 g / m ² (fiber diameter: 7 μm) produced by a needle punch method. A silica glass nonwoven fabric was used. In addition, the water retention of the silica glass nonwoven fabric is the amount of increase in mass relative to the original mass of the silica glass nonwoven fabric when the silica glass nonwoven fabric is immersed in distilled water for 10 minutes and then gently lifted and left standing for 10 minutes. It was calculated | required by calculating the ratio of. The suction height is the height of the water surface sucked up by the silica glass nonwoven fabric when 2 cm below the silica glass nonwoven fabric cut into a strip of 3 cm width is immersed in distilled water and held for 10 minutes. Say it. The total of photocatalyst titanium oxide and silica carrying the photocatalyst titanium oxide 15 g / m ² and silica 5 g / m ² by applying the photocatalyst coating liquid prepared in the above (1) to this silica glass nonwoven fabric by the dipping method. A photocatalyst-supporting porous material having a volume fraction of photocatalytic titanium oxide with respect to the amount of 59% was prepared.
(3) Sewage purification method and evaluation of the purification effect The photocatalyst-supported porous body produced in (2) above is cut into a 15 cm × 14 cm size flat plate and installed in a state of leaning against the ground at 45 °. Then, 1.0 mW / cm ² of ultraviolet light from a black light blue (BLB) lamp was continuously irradiated at an irradiation angle of 45 °.
On the other hand, at the upper end of the photocatalyst-supporting porous body, three dropping ports are installed at intervals of 4 cm in the width (15 cm) direction, and 2 L of 20 ppm methylene blue (basic substance to be decomposed) aqueous solution is supported at a flow rate of 3 mL / min. It was dripped at the porous body. The purification liquid that had flowed out from the lower end surface of the photocatalyst-supporting porous body was returned to the 2 L tank, and this operation was continued for 60 hours.
The concentration change of the methylene blue aqueous solution was quantified by the absorbance method. In the initial stage of purification, the concentration decreased rapidly due to the effects of both adsorption to the photocatalyst-supporting porous material and purification by the photocatalytic reaction, but the concentration reduction rate became constant after 12 hours. The decomposition rate at this time was 33 mg / m ² .
In the said photocatalyst-carrying porous material, K in formula (I) is a 45 mL / min, maximum _{F R} becomes 13.2 mL / min. Therefore, since three dripping ports are provided, the maximum flow rate is 39.6 mL / min.

Example 2
Photocatalyst-supported porous bodies having various volume fractions of photocatalytic titanium oxide with respect to the total amount of photocatalytic titanium oxide and silica were produced according to Example 1, and the purification effect of sewage was examined in the same manner as in Example 1. .
FIG. 2 is a graph showing the relationship between the volume fraction of photocatalytic titanium oxide and the decomposition rate constant.
The decomposition rate constant is a value obtained as follows. First, in the dark, an aqueous solution of methylene blue dye is circulated for one day to adsorb and saturate the methylene blue dye on the photocatalyst. The dye density at this time is defined as the initial density. After adjusting the initial concentration to 20 ppm and continuing to circulate, UV light irradiation with a BLB lamp is performed with an ultraviolet intensity of 1.0 mW / cm ² , and the change in the concentration of the methylene blue dye to be decomposed with respect to the irradiation time is obtained. The reaction rate constant is obtained from the initial slope of the graph. The concentration of methylene blue dye can be easily calculated from the absorbance at 660 nm.
As can be seen from FIG. 2, in order to exhibit high photocatalytic activity, the volume fraction of photocatalytic titanium oxide is preferably 30% or more, and more preferably 40% or more.

Example 3
A photocatalyst-supported porous body with a silica support amount fixed at 30 g / m ² and various photocatalyst titanium oxide support amounts was prepared according to Example 1, and the purification effect of sewage was examined in the same manner as in Example 1. It was.
FIG. 3 is a graph showing the relationship between the amount of photocatalytic titanium oxide supported and the decomposition rate constant.
As can be seen from FIG. 3, the photocatalytic activity is saturated when the supported amount of photocatalytic titanium oxide is around 8 g / m ² , and the photocatalytic activity hardly changes even when the supported amount of titanium oxide is increased.

Examples 4-6
Using the plate-like photocatalyst-supported porous body having a size of 15 cm × 14 cm prepared in Example 1, 10 ° (Example 4), 30 ° (Example 5) and 60 ° (Example 6) with respect to the ground, respectively. The same operation as in Example 1 was carried out except that the 100 ppm methylene blue aqueous solution was dropped onto the photocatalyst-supported porous body at a rate of 2 mL / min. The relationship between the treatment time and the methylene blue concentration in the treatment solution is shown in a graph in FIG.

Incidentally, showing the maximum flow rate to be calculated from the maximum F _R and it was determined from the formula (I) below.
Maximum _F R (mL / min) maximum flow rate (mL / min)
Example 4 0.684 2.1
Example 5 6.03 18.1
Example 6 22.5 67.5

Comparative Example 1
The plate-like photocatalyst-supported porous body having a size of 15 cm × 14 cm prepared in Example 1 was used, immersed in 20 L of 100 ppm methylene blue aqueous solution at an angle of 0 ° with respect to the ground, and irradiated with ultraviolet light from a BLB lamp at an irradiation angle of 45 °. Continued. The relationship between the treatment time and the methylene blue concentration in the treatment solution is shown in a graph in FIG.
As can be seen from FIG. 4, when the photocatalyst-supporting porous body is at an angle of 0 ° with respect to the ground, that is, in the state of being laid, photolysis proceeds slowly, but if it is tilted to 10 ° or more, it is effectively decomposed. However, when the angle is low, the maximum flow rate is small, and as a result, processing takes time. Considering the maximum flow rate, an angle of 60 ° or more is preferable.

Example 7
(1) Preparation of photocatalyst coating liquid Photocatalytic titanium oxide (anatase type titanium oxide, average particle size 20 nm) slurry [manufactured by Titanium Industry Co., Ltd., “PC-203”, solid content 20% by mass] 11.6 g, inorganic adhesion 8.5 g of amorphous titania binder (7.1% by mass of solid component) as a component is mixed with a mixed solution of ethyl cellosolve and water (ethyl cellosolve / water = 90/10, mass ratio) to obtain a solid component concentration of 0 An 8 mass% coating solution was prepared.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 40 °.
(2) Production of photocatalyst-supporting porous material The silica glass nonwoven fabric produced by the needle punch method is coated with the photocatalyst coating liquid prepared in (1) above to carry 15.0 g / m ² of photocatalytic titanium oxide, A photocatalyst-supporting porous body having a volume fraction of photocatalytic titanium oxide in the film of 70% was produced. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of the purification effect The photocatalyst-supporting porous material produced in (2) above is cut into a 15 cm × 14 cm size flat plate and installed in a state of leaning against the ground at 45 °. Then, 1.0 mW / cm ² of ultraviolet light from a black light blue (BLB) lamp was continuously irradiated at an irradiation angle of 45 °.
On the other hand, at the upper end of the photocatalyst-supported porous body, 14 dropping ports were installed at 1 cm intervals in the width (15 cm) direction, and 2 L of benzoic acid (acid decomposed product) -containing aqueous solution having a concentration of 20 ppm was flowed at a flow rate of 3 mL / min. It was dripped at the photocatalyst carrying porous body. The purification liquid that had flowed out from the lower end surface of the photocatalyst-supporting porous body was returned to the 2 L tank, and this operation was continued for 60 hours. The decomposition constant of benzoic acid in 30 to 60 hours after the start of the test was 59 (ppm / h) as shown in Table 1 below.

Example 8
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1 mass%) 8.5 g as an inorganic adhesive component was changed to 9.7 g, and alumina sol (manufactured by Nissan Chemical Industries, Ltd., “Alumina sol 520”), A coating solution having a solid component concentration of 0.9% by mass was prepared in the same manner as in Example 7 (1) except that 1.7 g (solid content 20% by mass) was added.
(2) Production of photocatalyst-supporting porous material In the same manner as in Example 7 (2), the silica glass nonwoven fabric produced by the needle punch method was coated with the coating solution prepared in (1) above to produce photocatalytic titanium oxide 15 1.0 g / m ² and alumina (boehmite-like crystal, average particle size 80 nm) 2.2 g / m ² are supported, the volume fraction of photocatalytic titanium oxide in the coating film is 67%, and the volume fraction of alumina is 11%. A photocatalyst-supporting porous material was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of its purification effect (i) Using the photocatalyst-supporting porous material produced in (2) above, a test was conducted in the same manner as in Example 7 (3). The decomposition constant A of benzoic acid over time was 70 (ppm / h) as shown in Table 1.

Example 9
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1% by mass) 8.5 g as an inorganic adhesive component was changed to 10.4 g, and alumina sol (manufactured by Nissan Chemical Industries, Ltd., “Alumina sol 520”), A coating liquid having a solid component concentration of 0.9 mass% was prepared in the same manner as in Example 7 (1) except that 2.8 g of a solid content of 20 mass% was added.
(2) Production of photocatalyst-supporting porous material In the same manner as in Example 7 (2), the silica glass nonwoven fabric produced by the needle punch method was coated with the coating solution prepared in (1) above to produce photocatalytic titanium oxide 15 1.0 g / m ² and alumina (boehmite crystals, average particle size 80 nm) 3.6 g / m ² are supported, the volume fraction of photocatalytic titanium oxide in the coating film is 62%, and the volume fraction of alumina is 16%. A photocatalyst-supporting porous material was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Evaluation of sewage purification method and its purification effect Using the photocatalyst-supported porous material prepared in (2) above, a test was conducted in the same manner as in Example 7 (3). The decomposition constant A of the acid was 74 (ppm / h) as shown in Table 1.

Example 10
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1 mass%) 8.5 g, which is an inorganic adhesive component, was changed to 11.3 g, and alumina sol (Nissan Chemical Industries, Ltd., “Alumina sol 520”), A coating liquid having a solid component concentration of 1.0% by mass was prepared in the same manner as in Example 7 (1) except that 4.0 g of 20% by mass was added.
(2) Production of photocatalyst-supporting porous material In the same manner as in Example 7 (2), the silica glass nonwoven fabric produced by the needle punch method was coated with the coating solution prepared in (1) above to produce photocatalytic titanium oxide 15 1.0 g / m ² and alumina (boehmite-like crystal, average particle size 80 nm) 3.6 g / m ² are supported, the volume fraction of photocatalytic titanium oxide in the coating film is 57%, and the volume fraction of alumina is 21%. A photocatalyst-supporting porous material was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of its purification effect (i) Using the photocatalyst-supporting porous material produced in (2) above, the test was conducted in the same manner as in Example 7 (3). The decomposition constant A of benzoic acid over time was 71 (ppm / h) as shown in Table 1.
(Ii) The photocatalyst-supported porous material produced in (2) above is cut into a 15 cm × 14 cm size flat plate, and is placed in a state of leaning at 45 ° with respect to the ground, and 1.0 mW / cm by a BLB lamp. No. ² ultraviolet light was continuously irradiated at an irradiation angle of 45 °.
Industrial waste liquid in which 14 dropping ports are installed at 1 cm intervals in the width (15 cm) direction at the upper end of the photocatalyst-supporting porous body, and the total organic carbon content (TOC) is 200, 400, 600, and 800 mg / L, respectively. (Sample in which sewage components are mainly basic organic substances and a small amount of acidic sewage components coexist) 2 L of each was dropped onto the photocatalyst-supporting porous body at a flow rate of 3 mL / min. The purification liquid that had flowed out from the lower end surface of the photocatalyst-supporting porous body was returned to the 2 L tank, and this operation was continued for 60 hours. Moreover, the benzoic acid of the acidic decomposition target object in a waste liquid is 20 ppm, the total organic carbon amount is 100 mg / L, and even if the total organic carbon amount changed, this decomposition target object amount was made the same. As shown in Table 1, the decomposition constant B of benzoic acid calculated from the benzoic acid concentration at 30 hours and 60 hours after the start of the test was 59 (ppm / h) for the waste liquid of TOC200 (mg / L), TOC400 (mg / L). The waste liquid of L) was 56 (ppm / h), the waste liquid of TOC600 (mg / L) was 55 (ppm / h), and the waste liquid of TOC800 (mg / L) was 55 (ppm / h).

Example 11
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1 mass%) 8.5 g, which is an inorganic adhesive component, is 13.5 g, and alumina sol (Nissan Chemical Industries, Ltd., “Alumina sol 520”), A coating solution having a solid component concentration of 1.2% by mass was prepared in the same manner as in Example 7 (1) except that 7.2 g of 20% by mass (solid content) was added.
(2) Production of photocatalyst-supporting porous material In the same manner as in Example 7 (2), the silica glass nonwoven fabric produced by the needle punch method was coated with the coating solution prepared in (1) above to produce photocatalytic titanium oxide 15 1.0 g / m ² and alumina (boehmite-like crystal, average particle size 80 nm) 9.3 g / m ² are supported, the volume fraction of photocatalytic titanium oxide in the coating film is 47%, and the volume fraction of alumina is 31%. A photocatalyst-supporting porous material was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of its purification effect (i) Using the photocatalyst-supporting porous material produced in (2) above, the test was conducted in the same manner as in Example 7 (3). The decomposition constant A of benzoic acid over time was 65 (ppm / h) as shown in Table 1.
(Ii) Using the photocatalyst-supported porous material prepared in (2) above, the same test as in Example 10 (3) (ii) was conducted. The decomposition constant B of benzoic acid at 30 to 60 hours after the start of the test was As shown in Table 1, the waste liquid of TOC200 (mg / L) is 65 (ppm / h), the waste liquid of TOC400 (mg / L) is 63 (ppm / h), and the waste liquid of TOC600 (mg / L) is 60 (Ppm / h), the waste liquid of TOC800 (mg / L) was 58 (ppm / h).

Example 12
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1 mass%) 8.5 g, which is an inorganic adhesive component, was changed to 16.9 g, and alumina sol (Nissan Chemical Industry Co., Ltd., “Alumina sol 520”, A coating solution having a solid component concentration of 1.5% by mass was prepared in the same manner as in Example 7 (1) except that 12.0 g (solid content 20% by mass) was added.
(2) Production of photocatalyst-supporting porous material In the same manner as in Example 7 (2), the silica glass nonwoven fabric produced by the needle punch method was coated with the coating solution prepared in (1) above to produce photocatalytic titanium oxide 15 1.0 g / m ² and alumina (boehmite-like crystal, average particle size 80 nm) 15.5 g / m ² are supported, the volume fraction of photocatalytic titanium oxide in the coating film is 37%, and the volume fraction of alumina is 41%. A photocatalyst-supporting porous material was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Evaluation of sewage purification method and its purification effect Using the photocatalyst-supported porous material produced in (2) above, a test was conducted in the same manner as in Example 10 (3) (ii). As shown in Table 1, the decomposition constant B of benzoic acid over time is 60 (ppm / h) for waste liquid of TOC200 (mg / L), 58 (ppm / h) for waste liquid of TOC400 (mg / L), and TOC600. The waste liquid of (mg / L) was 58 (ppm / h), and the waste liquid of TOC800 (mg / L) was 55 (ppm / h).

Example 13
(1) Preparation of photocatalyst coating solution
Photocatalytic titanium oxide (anatase type titanium oxide, average particle size 20 nm) slurry [made by Titanium Industry Co., Ltd., “PC-203”, solid content 20 mass%] 11.59 g, amorphous titania binder (solid component) 7.1 mass%) 8.45 g was mixed in a mixed solvent of ethyl cellosolve, 1-propanol and water (ethyl cellosolve / 1-propanol / water = 45/45/10, mass ratio) to obtain a solid component. A coating solution having a concentration of 0.75% by mass was prepared.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 40 °.
(2) Production of photocatalyst-supporting porous material The coating liquid prepared in (1) above was applied to a silica glass nonwoven fabric according to Example 1 to support photocatalytic titanium oxide 15 g / m ^2, and A photocatalyst-supporting porous body having a volume fraction of 79% of photocatalytic titanium oxide was produced. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of the purification effect The photocatalyst-supported porous body produced in (2) above is cut into a 15 cm × 14 cm size flat plate and installed in a state of leaning against the ground at 45 °. Then, 1.0 mW / cm ² ultraviolet light from a BLB lamp was continuously irradiated at an irradiation angle of 45 °.
On the other hand, 14 dripping ports were installed at the upper end of the photocatalyst-supporting porous body at intervals of 1 cm in the width (15 cm) direction, and paddy rice seed disinfectant [Kumiai Chemical Industry Co., Ltd., Techlead C Flowable] was used with 500 water. A 2 liter diluted solution of ipconazole (hydrophobic substance to be decomposed) having a concentration of 20 ppm was dropped onto the photocatalyst-supporting porous body at a flow rate of 3 mL / min. The purification liquid that had flowed out from the lower end surface of the photocatalyst-supporting porous body was returned to the 2 L tank, and this operation was continued for 60 hours. The degradation constant of ipconazole in 30 to 60 hours after the start of the test was 66 (ppm / h) as shown in Table 2 below.

Example 14
(1) Preparation of photocatalyst coating solution
8.45 g of amorphous titania binder (solid component 7.1% by mass), which is an inorganic adhesive component, is 8.56 g, and activated carbon (“Futamura Chemical Co., Ltd.,“ Dazai activated carbon SA-1000 ”) has a pore diameter of 10 nm or more. The solid component concentration was 0.76 mass in the same manner as in Example 13 (1) except that 0.03 g of the total pore volume was 20% or more with respect to the total pore volume and the average particle size was 10 μm). % Coating solution was prepared. Table 2 shows the types of the activated carbon, the pore volume ratio, the average particle diameter, and the volume fraction.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 42 °.
(2) Production of photocatalyst-supporting porous body The coating liquid prepared in (1) above was applied to a silica glass nonwoven fabric in the same manner as in Example 13 (2), and photocatalytic titanium oxide 15 g / m ² and activated carbon 0. A photocatalyst-carrying porous body carrying ² g / m ^{2 and} having a volume fraction of photocatalytic titanium oxide in the coating film of 73% and a volume fraction of activated carbon of 5% was produced. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Evaluation of sewage purification method and purification effect Using the photocatalyst-supported porous material prepared in (2) above, the same test as in Example 13 (3) was conducted. The decomposition constant A was 71 (ppm / h) as shown in Table 2.

Example 15
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1 mass%) 8.45 g, which is an inorganic adhesive component, is 8.78 g, and 0.09 g of activated carbon (“Dazai activated carbon SA-1000”) is added. A coating liquid having a solid component concentration of 0.78% by mass was prepared in the same manner as in Example 13 (1) except that. Table 2 shows the types of the activated carbon, the pore volume ratio, the average particle diameter, and the volume fraction.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 47 °.
(2) Production of photocatalyst-supporting porous body The coating liquid prepared in (1) above was applied to a silica glass nonwoven fabric in the same manner as in Example 13 (2), and photocatalytic titanium oxide 15 g / m ² and activated carbon 0. A photocatalyst-carrying porous body carrying 6 g / m ^{2 and} having a volume fraction of photocatalytic titanium oxide in the coating film of 60% and a volume fraction of activated carbon of 21% was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Evaluation of sewage purification method and its purification effect Using the photocatalyst-supported porous material prepared in (2) above, a test was conducted in the same manner as in Example 13 (3). The decomposition constant A was 74 (ppm / h) as shown in Table 2.

Example 16
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1% by mass) 8.45 g, which is an inorganic adhesive component, was changed to 9.69 g, and activated carbon (“Dazai activated carbon SA-1000”) 0.34 g was added. A coating solution having a solid component concentration of 0.86% by mass was prepared in the same manner as in Example 13 (1) except that. Table 2 shows the type of activated carbon, the pore volume ratio, and the average particle diameter. The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 49 °.
(2) Production of photocatalyst-supporting porous body The coating liquid prepared in (1) above was applied to a silica glass nonwoven fabric in the same manner as in Example 13 (2), and photocatalytic titanium oxide 15 g / m ² and activated carbon 2. A photocatalyst-carrying porous body carrying ² g / m ^{2 and} having a volume fraction of photocatalytic titanium oxide in the coating film of 48% and a volume fraction of activated carbon of 35% was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of its purification effect (i) Using the photocatalyst-supporting porous material produced in (2) above, a test was conducted in the same manner as in Example 13 (3). The degradation constant A of ipconazole over time was 70 (ppm / h) as shown in Table 2.
(Ii) On the other hand, the photocatalyst-supporting porous material produced in (2) above was cut into a flat plate of 15 cm × 14 cm size, placed in a state of leaning at 45 ° with respect to the ground, and 1.0 mW from a BLB lamp. / Cm ² of ultraviolet light was continuously irradiated at an irradiation angle of 45 °.
Rice seeds with 14 dripping ports installed at 1 cm intervals in the width (15 cm) direction at the upper end of the photocatalyst-supporting porous body and having total organic carbon (TOC) of 200, 400, 600, and 800 mg / L, respectively. Disinfectant waste liquid (a sample in which sewage components are mainly hydrophilic organic substances and a small amount of hydrophobic sewage components coexist) was dropped into a photocatalyst-supporting porous body at a flow rate of 3 mL / min. The purification liquid that had flowed out from the lower end surface of the photocatalyst-supporting porous body was returned to the 2 L tank, and this operation was continued for 60 hours. The hydrophobic decomposition target in the waste liquid was 10 ppm each for ipconazole and fenitrothion, and the total organic carbon amount was 100 mg / L in total, and even if the total organic carbon amount changed, the decomposition target amount was the same. As shown in Table 2, the decomposition constant B of ipconazole calculated from the ipconazole concentration at 30 hours and 60 hours after the start of the test is 60 (ppm / h) for the waste liquid of TOC200 (mg / L), TOC400 (mg / L) Was 57 (ppm / h), TOC600 (mg / L) was 55 (ppm / h), and TOC800 (mg / L) was 55 (ppm / h).

Example 17
(1) Preparation of photocatalyst coating solution
Example 13 (1) except that 8.45 g of amorphous titania binder (solid component 7.1% by mass), which is an inorganic adhesive component, was changed to 10.4 g, and 0.55 g of activated carbon (“Dazai activated carbon SA-1000”) was added. ) To prepare a coating solution having a solid component concentration of 0.92% by mass. Table 2 shows the types of the activated carbon, the pore volume ratio, the average particle diameter, and the volume fraction.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 50 °.
(2) Production of photocatalyst-supporting porous body The coating liquid prepared in (1) above was applied to a silica glass nonwoven fabric in the same manner as in Example 13 (2), and photocatalytic titanium oxide 15 g / m ² and activated carbon 3. A photocatalyst-supporting porous body carrying 6 g / m ^{2 and} having a volume fraction of photocatalytic titanium oxide in the coating film of 39% and a volume fraction of activated carbon of 47% was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Sewage purification method and evaluation of its purification effect (i) Using the photocatalyst-supporting porous material produced in (2) above, a test was conducted in the same manner as in Example 13 (3). The degradation constant A of ipconazole over time was 67 (ppm / h) as shown in Table 1.
(Ii) When tested in the same manner as in Example 16 (3) (ii) using the photocatalyst-supported porous material prepared in (2) above, the decomposition constant B of ipconazole at 30 to 60 hours after the start of the test is As shown in Table 2, the waste liquid of TOC200 (mg / L) is 63 (ppm / h), the waste liquid of TOC400 (mg / L) is 60 (ppm / h), and the waste liquid of TOC600 (mg / L) is 60 ( ppm / h), the waste liquid of TOC800 (mg / L) was 58 (ppm / h).

Example 18
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1% by mass) 8.45 g, which is an inorganic adhesive component, was changed to 11.27 g, and activated carbon (“Dazai activated carbon SA-1000”) 0.80 g was added. A coating liquid having a solid component concentration of 1.00% by mass was prepared in the same manner as in Example 13 (1) except that. Table 2 shows the types of the activated carbon, the pore volume ratio, the average particle diameter, and the volume fraction.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 52 °.
(2) Production of photocatalyst-supporting porous body The coating liquid prepared in (1) above was applied to a silica glass nonwoven fabric in the same manner as in Example 7 (2), and photocatalytic titanium oxide 15 g / m ² and activated carbon 5. A photocatalyst-carrying porous body carrying ² g / m ^{2 and} having a volume fraction of photocatalytic titanium oxide in the coating film of 32% and a volume fraction of activated carbon of 55% was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Evaluation of sewage purification method and purification effect Using the photocatalyst-supported porous material prepared in (2) above, the test was conducted in the same manner as in Example 16 (3) (ii). As shown in Table 2, the degradation constant B of ipconazole over time is 60 (ppm / h) for the waste liquid of TOC200 (mg / L), 59 (ppm / h) for the waste liquid of TOC400 (mg / L), and TOC600 ( The waste liquid of mg / L was 59 (ppm / h), and the waste liquid of TOC800 (mg / L) was 56 (ppm / h).

Example 19
(1) Preparation of photocatalyst coating liquid Amorphous titania binder (solid component 7.1 mass%) 8.45 g, which is an inorganic adhesive component, is 12.29 g, and 1.09 g of activated carbon (“Dazai activated carbon SA-1000”) is added. A coating liquid having a solid component concentration of 0.75% by mass was prepared in the same manner as in Example 13 (1) except that. Table 2 shows the types of the activated carbon, the pore volume ratio, the average particle diameter, and the volume fraction.
The water contact angle when this coating solution was applied to the slide glass surface (smooth surface) was 58 °.
(2) Production of photocatalyst-supporting porous body The coating liquid prepared in (1) above was applied to a silica glass woven fabric in the same manner as in Example 13 (2) to produce photocatalytic titanium oxide 15 g / m ² and activated carbon 7. A photocatalyst-carrying porous body carrying 1 g / m ^2, having a photocatalytic titanium oxide volume fraction of 26% and an activated carbon carrying ratio of 62% in the coating film was prepared. In the photocatalyst-supporting porous material, K in the formula (I) was 45 mL / min.
(3) Evaluation of sewage purification method and purification effect Using the photocatalyst-supported porous material prepared in (2) above, a test was conducted in the same manner as in Example 16 (3) (ii). As shown in Table 2, the degradation constant B of ipconazole over time is 54 (ppm / h) for the waste liquid of TOC200 (mg / L), 56 (ppm / h) for the waste liquid of TOC400 (mg / L), and TOC600 ( The waste liquid of mg / L was 54 (ppm / h), and the waste liquid of TOC800 (mg / L) was 50 (ppm / h).

  The circulating sewage purification method of the present invention can make maximum use of the photocatalytic reaction, is simple and inexpensive, does not require a large space, uses sunlight, and various sewage, for example, agricultural chemical waste liquid, It is suitably used for purifying waste liquids and the like in hydroponics.

It is a basic layout in the sewage purification method of the present invention. It is a graph which shows the relationship between the volume fraction of photocatalytic titanium oxide in Example 2, and a decomposition rate constant. 6 is a graph showing the relationship between the amount of supported photocatalytic titanium oxide and the decomposition rate constant in Example 3. It is a graph which shows the relationship between the inclination degree of the photocatalyst carrying | support porous body in Examples 4-6, and a methylene blue decomposition degree.

Claims (11)

To-be-processed sewage is supplied to the upper end of the plate-like photocatalyst-supported porous body that is installed so that the sunlight hits it at an angle of 10 ° or more with respect to the ground, and the upper end of the photocatalyst-supported porous body is supplied. From a plurality of dripping ports provided in the width direction, per dripping port, the formula (I)
_{F R ≦ K (1-cosθ} ) ... (I)
[ _Wherein FR is the dropping flow rate per dropping port of the treated sewage, θ is the angle of the photocatalyst-carrying porous body with respect to the ground, and K is the photocatalyst-carrying porous body standing vertically and from the dropping port provided at the upper end thereof When the sewage to be treated is supplied, the maximum value of the water supply speed per dropping port is shown. ]
Recycling sewage dropwise at a satisfy the relationship flow rate F _R, after passed through the photocatalyst carrying porous body was recovered from the bottom end face, characterized in that it repeatedly supplied to the upper part of the photocatalyst-carrying porous body Purification method.   The circulating sewage purification method according to claim 1, wherein the plurality of dripping ports are provided at intervals of 3 to 10 cm. The flat photocatalyst-supported porous body contains at least the sun of an inorganic porous body containing a woven or non-woven fabric made of porous ceramics or inorganic fibers, having a water retention of 500 to 3000 mass%, and a suction height of 12 mm or more. It has a coating film containing a photocatalyst material and an inorganic adhesive component and / or an adsorbent on the surface that is exposed to light, the volume fraction of the photocatalyst material in the coating film is 30 to 90%, and the supported amount of the photocatalyst material There 8 to 20 g / m ^2, and a water contact angle of the coating film provided on the smooth surface is 60 ° or less, the circulation of claim 1 or 2 thickness and has a flat plate shape than 12mm Type wastewater purification method.   The circulating sewage purification method according to claim 3, wherein the inorganic adhesive component is an amorphous titania binder.   The circulation according to claim 3 or 4, wherein the adsorbent and / or the inorganic adhesive component has a solid basicity with an isoelectric point of pH 9.0 or more, and selectively decomposes and removes acidic sewage components. Type wastewater purification method.   The adsorbent and / or the inorganic adhesive component has a solid basicity with an isoelectric point pH of 9.0 or higher, and selectively decomposes and removes hydrophobic sewage components emulsified with a surfactant. Item 5. A circulating sewage purification method according to Item 3 or 4.   The adsorbent is alumina having an average particle size of 100 nm or less and a crystal form of boehmite, and the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body is 10 to 45%. The circulating sewage purification method according to claim 5 or 6.   The circulation according to claim 3 or 4, wherein the adsorbent and / or the inorganic adhesive component has solid acidity having an isoelectric point of pH of 3.0 or less, and selectively decomposes and removes basic wastewater components. Type wastewater purification method.   The circulating sewage according to any one of claims 1 to 4, wherein a water contact angle of a coating film provided on a smooth surface is 40 to 60 °, and a hydrophobic sewage component is selectively decomposed and removed. Purification method. The adsorbent that adsorbs hydrophobic sewage components is activated carbon, and the activated carbon has a ratio of the sum of the volumes of pores having a pore diameter of 10 nm or more of 19% or more of the total pore volume, and the average particle diameter Is 10 μm or less, and the volume fraction of the adsorbent in the coating film provided on the surface of the inorganic porous body is 5 to 60%, The circulating sewage purification method according to claim 9, A plate-like photocatalyst-supporting porous body having a thickness of less than 12 mm is laminated with a woven fabric having an intensity of 98 N / cm or more made of inorganic fibers or organic fibers on the surface opposite to the side of the photocatalyst-supporting porous body that is exposed to sunlight. The circulating sewage purification method according to any one of claims 3 to 10, which is used as a layer structure.

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