WO2008018177A1 - Process for production of photosemiconductor particles - Google Patents

Abstract

Photosemiconductor particles which each consist of a base made of a metal compound photosemiconductor and a ceramic fixed on at least part of the surface of the base wherein the ceramic is a compound different from the base; and a process for the production of the photosemiconductor particles which comprises the following steps (A) to (D): the step (A) of mixing the base with the ceramic or a raw material thereof and a water-containing solvent to prepare a mixed fluid containing both the base bearing the ceramic or a precursor thereof in a state fixed on at least part of the surface thereof and water; the step (B) of adding a coagulant to the mixed fluid and stirring the resulting fluid to form a solid matter which contains the base bearing the ceramic or a precursor thereof in a state fixed on at least part of the surface thereof and the coagulant; the step (C) of separating the solid matter from the water-containing solvent; and the step (D) of heating the solid matter to remove the coagulant through decomposition and thus obtain photosemiconductor particles.

Description

 Specification

 Method for producing optical semiconductor particles

 Technical field

 TECHNICAL FIELD [0001] The present invention relates to a base that is a metal compound optical semiconductor, and a method for producing optical semiconductor particles comprising ceramics immobilized on at least a part of the surface of the base.

 [0002] Metal compound optical semiconductors such as titania and zinc oxide exhibit the property of absorbing light having energy corresponding to the bandwidth. For this reason, application development is being attempted as an ultraviolet shielding agent in the fields of cosmetics and resin materials. Focusing on the high reactivity of holes and electrons generated in metal compound photo-semiconductors that absorb light, the photocatalyst is applied to environmental purification such as water purification, antifouling, antibacterial, deodorization, and air purification. Attempts have also been made.

 [0003] When a metal compound optical semiconductor is used for these applications, the metal compound optical semiconductor may be used as it is, but improvement may be achieved by immobilizing different compounds on the surface. For example, metal oxide particles whose surface is coated with dense silica (see Patent Document 1), pigments whose surface is coated with a silicon compound and an aluminum compound (see Patent Document 2), silica hydrate coating layer Titanium oxide photocatalyst for basic gas removal (see Patent Document 3), high-activity photocatalyst coated with a silicon oxide film substantially free of pores (see Patent Document 4), partially coated with calcium phosphate Photocatalysts (see Patent Document 5).

[0004] A method of immobilizing different compounds on the surface of a metal compound optical semiconductor includes a gas phase method in which a gaseous raw material is reacted with a metal compound optical semiconductor (see Patent Document 6), or treatment in a solvent. There is a liquid phase method. Among these, the liquid phase method is excellent in that heat removal can be easily performed and the amount of raw materials to be reacted can be easily controlled. Examples of liquid phase methods include a method in which silicate and sulfuric acid are dropped while heating in a basic aqueous solution (see Patent Document 7), water is adsorbed in advance on the surface of an optical semiconductor in an organic solvent, and a metal alkoxy A method of hydrolyzing a metal on the surface of an optical semiconductor (see Patent Document 8), a production method of coating with silicate in an acidic aqueous medium having a pH of 5 or less (see Patent Document 4), Na, , Cl, Ca, P, Mg, etc. (see Patent Document 5).

 It is known to simplify solid-liquid separation using a flocculant, and it is industrially used to treat wastewater and sewage. By using the flocculant, fine particles dispersed in the liquid are joined together to form coarse particles, so-called flocs. For this reason, the solid matter is easily separated as an effect of the flocculant. Examples of simplifying solid-liquid separation using a flocculant in a method for producing a metal compound optical semiconductor include polybasic mineral acids, organic acid or phenols having two or more hydroxyl groups and / or hydroxyl groups, and those A method of treating with at least one of the above salts and at least one organic polymer flocculant (see Patent Document 9), and metatitanic acid generated by hydrolysis of titanium sulfate is aggregated with the polymer flocculant A method (see Patent Document 10) is disclosed. In Patent Documents 9 and 10, in a method for producing optical semiconductor particles comprising a base that is a metal compound optical semiconductor and ceramics immobilized on at least a part of the surface of the base, There is no mention of the use of chemicals.

Patent Document 1: Japanese Patent No. 3570730

Patent Document 2: Japanese Patent No. 539263

Patent Document 3: Japanese Patent Application Laid-Open No. 2002_159865

Patent Document 4: Japanese Patent Application No. P CT / J P 2006/302542

Patent Document 5: Japanese Patent No. 3275032

Patent Document 6: Japanese Patent No. 1 895322

Patent Document 7: Japanese Patent Laid-Open No. 02-296726

Patent Document 8: Japanese Patent No. 2832342

Patent Document 9: Japanese Patent Laid-Open No. 53-39296

Patent Document 10: Japanese Patent No. 3554803

Disclosure of the invention [0006] In the field of utilizing optical semiconductor particles as an ultraviolet shielding agent, a material that is transparent to visible light and absorbs ultraviolet rays is required. Therefore, optical semiconductor particles have been proposed in which the particle diameter of the metal compound optical semiconductor is less than half the wavelength of visible light. In the field where photo semiconductor particles are used as a photocatalyst, a material having a large specific surface area, which is characterized by high effects such as deodorization and air purification, has been proposed. In both cases, by making the particle diameter finer than the conventional one, transparency to visible light or a large specific surface area is achieved. However, when producing fine particles by the liquid phase method, the following points (a) or (b) are problematic because the handled optical semiconductor particles contain fine particles:

 (a) When collecting optical semiconductor particles by filtration, the processing speed is long due to the low flow rate of the filter.

 (b) When recovery of the photo semiconductor particles is performed with a thickener, that is, when concentration separation is performed by sedimentation of the photo semiconductor particles, the time required for the settling is long, so that the processing takes time.

 As a result, there is a problem that the optical semiconductor particles cannot be easily recovered from the solvent.

 [0007] Therefore, the present invention provides a production method in which solid-liquid separation can be easily performed when producing optical semiconductor particles by a liquid phase method, and the operation of the obtained optical semiconductor particles as an optical semiconductor is not affected. The challenge is to provide a method.

 [0008] In order to solve the above-mentioned problems, the present inventors diligently studied using a slurry containing a substrate having a ceramic surface fixed thereto. As a result, the flocculant is added to solid-liquid separate the particles containing the substrate in the agglomerated state, and the resulting solid is heated to decompose the flocculant and from the substrate having ceramics immobilized on the surface. It has been found that the optical semiconductor particles can be easily produced. At the same time, the inventors have found that the obtained optical semiconductor particles exhibit the same performance as the optical semiconductor particles produced without using a flocculant, and have completed the invention. That is, according to the present invention, the following method for producing optical semiconductor particles is provided.

[1] A base that is a metal compound optical semiconductor, and at least one of the surfaces of the base A method for producing optical semiconductor particles comprising ceramics fixed to a part, wherein the ceramics is a compound different from the substrate, and comprising the following steps (A) to (D) :

 (A) a step of mixing the substrate, the ceramic or its raw material, and a water-containing solvent to prepare a mixed solution containing the substrate and water on which the ceramic or its precursor is immobilized on at least a part of the surface;

 (B) adding a flocculant to the mixed solution, stirring, and obtaining a solid body containing the base and the flocculant on which the ceramic or its precursor is fixed at least on a part of the surface;

 (C) recovering the solid from the water-containing solvent,

 (D) A step of decomposing and removing the flocculant by heating the solid to obtain photo-semiconductor particles.

 [2] Between the steps (B) and (C), or between the steps (C) and (D), further comprising the following step (E): Production method:

 (E) A step of washing the solid body containing the substrate and the flocculant on which the ceramic or its precursor is immobilized on at least a part of the surface.

 [3] The step (E) is based on the flow of the water-containing solvent, and the flow rate of the liquid in the portion separating the solid and the washing waste liquid is determined by the horizontal vector component and the vertical direction. When divided into vector components, washing is performed by controlling the supply amount of the hydrous solvent so that the rising rate of the liquid as a vector component in the vertical direction is slower than the settling rate of the solids. [2] The method for producing an optical semiconductor particle according to [2].

 [4] The method for producing optical semiconductor particles according to [1] or [2], wherein the flocculant is a polymer flocculant.

 [5] The method for producing an optical semiconductor particle according to [4], wherein the polymer flocculant is a nonionic type.

[6] The polymer flocculant is a polymer compound containing one or more partial structures selected from the group consisting of acrylamide or a modified product thereof as a repeating unit. The method for producing an optical semiconductor particle according to [4].

 [7] The photo-semiconductor particle according to any one of [1], [2], or [4], wherein the heating temperature in the step (D) is 400 ° C. or higher and 1 000 ° C. or lower. The manufacturing method

 [8] The method for producing optical semiconductor particles according to any one of [1], [2], [4], and [7], wherein the substrate is made of titanium oxide.

 [9] The method for producing optical semiconductor particles according to [1] or [8], wherein the ceramic is made of silicon oxide.

 [10] The step (A) force is selected from the group consisting of a hydrous solvent containing the substrate and a silicate, a hydrous solvent containing the silicate and the substrate, and a hydrous solvent containing the substrate and a hydrous solvent containing the silicate. The method for producing optical semiconductor particles according to [9], wherein at least one set is mixed and the pH of the mixed solution containing both the substrate and the silicate is maintained at 5 or less. .

 [1 1] The silicon oxide is fixed in a film form on at least a part of the surface of the substrate, and in pore size distribution measurement in a region of 20 to 500 angstroms by a nitrogen adsorption method, The method for producing optical semiconductor particles according to [1 0], which is a silicon oxide film having no pores.

[1 2] The amount of silicon supported per 1 m ² of the surface area of the optical semiconductor particles is 0.1 mg or more and 2. Omg or less, according to any one of [9] to [1 1] Method for producing optical semiconductor particles.

 [1 3] The method for producing an optical semiconductor particle according to [1 1], wherein the optical semiconductor particle contains an alkali metal in an amount of 1 ppm or more and 1 O 2 O O ppm or less.

 [1 4] The method for producing optical semiconductor particles according to [1 3], wherein the silicon oxide contains an alkali metal.

 [15] The method for producing optical semiconductor particles according to [8], wherein the ceramic is composed of a compound of calcium and phosphorus.

[16] The method for producing an optical semiconductor particle according to [15], wherein the ceramic is a parameter. [17] The method for producing optical semiconductor particles according to [15], wherein the step (A) is a step of forming a compound containing calcium and phosphorus on the surface of the substrate using a force simulated body fluid.

 [18] The method for producing optical semiconductor particles according to [8], wherein the ceramic is a ceramic made of an oxide containing at least one of magnesium and aluminum as a constituent component.

 [19] The method for producing optical semiconductor particles according to [18], wherein the ceramic is a mixture of an oxide of magnesium and aluminum, or a ceramic composed of a composite oxide of magnesium and aluminum.

 [20] The step (A) is a step of mixing a hydrous solvent containing at least one or more water-soluble salts of magnesium and aluminum with a hydrous solvent containing the substrate and the alkali metal salt. [18] A method for producing the optical semiconductor particles described in 1.

 [21] The method for producing optical semiconductor particles according to any one of [9], [15], and [18], wherein the optical semiconductor particles are a photocatalyst.

[0010] According to the present invention, when producing a semiconductor substrate, which is a metal compound optical semiconductor, and optical semiconductor particles comprising ceramics fixed to at least a part of the surface of the substrate, by a liquid phase method, It is possible to provide a production method in which liquid separation can be easily performed and the obtained optical semiconductor particles do not affect the action as an optical semiconductor.

 Brief Description of Drawings

 [0011] The above-described object and other objects, features, and advantages will be further clarified by a preferred embodiment described below and the following screens that accompany it.

 FIG. 1 is a diagram showing an I og differential pore volume distribution curve (solid line) of optical semiconductor particle 1 and an I og differential pore volume distribution curve (dotted line) of titanium dioxide ST_01 corresponding to the substrate.

[Figure 2] Iog differential pore volume distribution curve (solid line) of photo-semiconductor particle 5 and its substrate It is a figure which shows Iog differential pore volume distribution curve (dotted line) of applicable titanium dioxide ST_01.

 [Fig. 3] A diagram showing the I og differential pore volume distribution curve (solid line) of photo-semiconductor particle 6 and the I og differential pore volume distribution curve (dotted line) of titanium dioxide P _ 2 5 corresponding to the substrate. is there.

 BEST MODE FOR CARRYING OUT THE INVENTION

 The optical semiconductor particles produced in the present invention are composed of a base that is a metal compound optical semiconductor and ceramics immobilized on at least a part of the surface of the base. The photosemiconductor particles may be independently configured as described above, and all the particles may have the same configuration, or may be a mixture of two or more differently configured particles. Good. Further, two or more kinds of ceramics may be fixed to one substrate. In addition, the term “consisting of” does not exclude the case where other components are included, and includes both the case where only the mentioned components are included and the case where other components are also included. Shall mean.

 [0013] The substrate is not particularly limited as long as it is a metal compound optical semiconductor. Examples include titanium oxide, zinc oxide, tungsten oxide, and strontium titanate. The substrate preferably has a crystallite diameter derived from X-ray diffraction (X R D) in the range of 1 to 500 nm. The shape is not particularly limited, and examples thereof include a spherical shape, a spheroid shape, a column shape, a geometric shape, and a flake shape. Furthermore, a substrate having ceramics immobilized on at least a part of its surface can be used as the substrate of the present invention. In many cases, only one type of substrate is used, but a mixture of two or more types may be used.

[0014] When the present invention is carried out as a method for producing a photocatalyst, titanium oxide is preferable because it is excellent in photocatalytic activity and is excellent in safety and stability. Examples of titanium oxide include amorphous, anatase type, rutile type, and wurtzite type titanium dioxide, and among these, anatase type, rutile type, or a mixture thereof, which is superior in photocatalytic activity, is more suitable. preferable. These may contain a small amount of amorphous material. As a substrate, one or more transition metals are added to the metal compound optical semiconductor. Addition or support, Metal compound semiconductor with one or more typical elements of Group 14, 15 and / or Group 16 added or supported, Optical semiconductor composed of two or more metal compounds A mixture of two or more kinds of metal compound semiconductors may be used.

 [0015] The ceramic is not particularly limited as long as it is a compound different from the base constituting the optical semiconductor particles. Therefore, it may be a metal compound optical semiconductor. For example, when the substrate is titanium oxide, the ceramic may be zinc oxide. When the present invention is carried out as a method for producing cosmetics, pigments, or photocatalysts, the ceramic is preferably an oxide of Si, AI, Zr, or Ce, or a calcium compound. The oxide may include a hydroxyl group, adsorbed water, etc., and may be a single oxide, a binary complex oxide, or a multicomponent complex oxide. And it is not limited to the said metal, Other metal elements may be included as an ion or a metal. In the production method of the present invention, in the step (D), heat treatment is performed to decompose the flocculant. Therefore, the ceramic constituting the optical semiconductor particles provided by the production method of the present invention is a fired ceramic.

 [001 6] Calcium compounds include calcium phosphates or silicates, such as hydroxyapatite, fluorideapatites, and hydroxyapatites containing other metal ions. And calcium phosphate salt having a mineral composition known as Calcium silicate.

 [001 7] Of the above oxides or compounds, an oxide of Si is more preferable. When the Si oxide is immobilized on the surface of the substrate, the heat resistance of the substrate is improved. This allows the flocculant to be decomposed at higher temperatures.

[0018] The ceramic raw material forms a ceramic or a precursor thereof on the surface of the substrate by causing hydrolysis, condensation, precipitation or the like when mixed with the substrate and the water-containing solvent in the step (A). It is a substance. Ceramic materials may be used alone or in combination of two or more. For example, metal halides, nitrates or sulfates, metal alkoxides, metal complexes, metal oxoacid salts And the like can be mentioned as raw materials used alone. Examples of the metal oxo acid salt include sodium silicate and potassium silicate as Si oxo acid salt. Examples of the raw material used in two or more types include a combination of a metal-soluble salt and a soluble oxoacid or a salt thereof. When the above combination is used as a raw material, an insoluble or hardly soluble oxoacid salt of the metal is precipitated on the surface of the substrate to become a ceramic or a precursor thereof. For example, when calcium chloride and sodium phosphate are used as raw materials, a phosphate compound is precipitated. When the ceramic is silicon oxide, examples of the raw material include silicic acid, silicate, silicate ester, silicon halide, organohydridopolysiloxane. In addition, a precipitating agent or a catalyst may be used for forming ceramics or a precursor thereof.

[0019] A ceramic precursor is a compound that changes into a ceramic by a physical or chemical treatment. In the process of the present invention, the ceramic precursor may be converted into ceramics, or a process of converting into ceramics may be provided separately. Among the steps of the present invention, those converted into ceramics include those that become ceramics by oxidation, hydrolysis, condensation reaction, etc. in the heat treatment in step (D). An example of such a precursor is aluminum hydroxide. Aluminum hydroxide is a compound that is formed on the surface of a substrate using aluminum alkoxide as a raw material and can be converted to alumina in the step (D).

 [0020] The water-containing solvent is water or a mixed solvent mainly containing water. The water-containing solvent may include a water-soluble organic solvent having 1 to 4 carbon atoms among organic solvents classified into alcohols, ketones, ethers, or esters. Specific examples of the water-containing solvent include water, water and methyl alcohol, water and ethyl alcohol, water and isopropanol, and the like. Of these, water is preferred. These water or mixed solvents may be used alone or in combination of two or more.

[0021] In the step (A), a substrate, ceramics or a raw material thereof, and water-containing There is no restriction | limiting in particular in the method of mixing a medium. For example, (a) a method of mixing a ceramic or its raw material after mixing the substrate with a hydrous solvent, (b) a mixed solution of mixing the hydrous solvent and the substrate, and a mixed solution of mixing the hydrous solvent and ceramics or its raw material (C) A method of mixing a ceramic or its raw material in a water-containing solvent and then mixing the substrate, (d) A mixed solution containing the substrate, the ceramic or its raw material, and a water-containing solvent (E) When the ceramic is formed by reacting two or more kinds of raw materials, the mixture containing the hydrous solvent, the substrate, and the first raw material of the ceramic is mixed. And a method of mixing two of a liquid and a mixed liquid obtained by mixing a hydrous solvent and a second ceramic raw material. The mixing is not particularly limited as long as the water-containing solvent can exist as a liquid, and may be performed at room temperature or appropriately under cooling, heating, and pressurizing conditions. Further, the mixed solution thus prepared may be appropriately aged.

 [0022] The mixed solution prepared in the step (A) includes a substrate having ceramics or a precursor thereof immobilized on at least a part of the surface and water. The mixed liquid does not necessarily need to be composed only of these. Organic solvents classified as unreacted ceramic raw materials, by-products generated during the formation of the ceramic precursor, alcohols, ketones, ethers, or esters. Among them, it may contain a water-soluble organic solvent having 1 to 4 carbon atoms.

 [0023] The concentration of the substrate relative to the total weight of the mixed solution prepared in step (A) (hereinafter referred to as slurry concentration as appropriate) is preferably 0.5 wt% or more and 40 wt% or less. More preferably, it is more than 20% by weight. When the slurry concentration is equal to or higher than the lower limit, productivity is increased, and when the slurry concentration is lower than the upper limit, the specific gravity of the liquid can be prevented from becoming excessive, and economic efficiency can be ensured.

There is no particular limitation on the dispersed particle size of the substrate obtained by the step (A), on which the ceramic or its precursor is immobilized on at least a part of the surface. The force average particle size is 1 The average particle diameter is preferably 0 m or less, and more preferably 3 m or less. In this case, the solid matter is easily agglomerated by agglomerating the fine particles. The feature of the present invention is that it can be collected in the stool.

 [0025] The concentration of water in the mixed solution prepared in the step (A) is preferably 60% by weight or more, more preferably 80% by weight or more, when expressed as the weight of water with respect to the total weight of the mixed solution. Within such a range, the flocculant is easy to dissolve, and the agglomeration effect is manifested. The water contained in the mixed solution may be finally in the above range. Therefore, a preparation method that uses only water as the water-containing solvent and falls within the above range upon completion of mixing may be used. Moreover, after forming the optical semiconductor particles in an organic solvent, water may be added for adjustment. Furthermore, when the mixed solution contains inorganic salts such as neutralized salts, the flocculant may not be effective due to the salting-out action, so even if the water concentration is within this range, the water content can be increased by decanting. Substitution of the solvent may be performed.

 [0026] Specific examples of the mixing method in the step (A) are shown below.

 [0027] (1. Method of mixing while maintaining pH of 5 or less in mixed liquid containing substrate, ceramic or raw material, and water-containing solvent)

 In step (A), for example, a hydrous solvent and a silicate containing a substrate that is a metal compound optical semiconductor, a hydrous solvent containing a silicate and the substrate, and a hydrous solvent containing the substrate and a hydrous solvent containing a silicate, Mix at least one set. Then, the pH of the mixed solution containing both the substrate and silicate is maintained at 5 or less and mixed.

[0028] In this example, the ceramic contains silicon oxide. Here, as a method of maintaining the pH at 5 or less, when mixing the substrate, the silicate, and the hydrous solvent, the pH of the hydrous solvent is constantly measured, and adjusted by adding an acid and a base as appropriate. It doesn't matter how. However, it is easy to neutralize the total amount of the base components contained in the silicate used for the production, and to make a sufficient amount of acid present in the water-containing solvent beforehand so that the pH is 5 or less. In this case, as the silicate, a salt of silicic acid and / or its oligomer may be used, and two or more kinds may be mixed and used. Sodium and potassium salts are preferred because they are easily available industrially, and the dissolution step can be omitted, so that a sodium silicate aqueous solution (JISK 1408 "water glass") is further used. Is preferable. Any acid can be used, but a mineral acid such as hydrochloric acid, nitric acid, or sulfuric acid is preferably used. The acids may be used alone or in combination of two or more. The base does not need to be used separately when using the above-described method in which a sufficient amount of acid to have a pH of 5 or less is previously present in the aqueous solvent. However, when using a base, any base can be used. Of these, metal hydroxides such as hydroxy hydroxide and sodium hydroxide are preferably used.

[0029] (2. Method of mixing substrate after mixing ceramic or raw material in water-containing solvent)

 In step (A), for example, a compound containing calcium and phosphorus is formed on the surface of the substrate using a simulated body fluid. The specific mixing procedure is as follows. First, a simulated body fluid is prepared, and then the substrate is mixed. In this example, an apatite, which is a kind of calcium phosphate, is formed as ceramics.

[0030] Here, the simulated body fluid refers to sodium chloride, potassium chloride, sodium bicarbonate, dipotassium hydrogen phosphate, magnesium chloride, calcium chloride, sodium sulfate, or sodium fluoride dissolved in water. This means a solution prepared by adjusting the pH to 7 to 8 with an acid base such as namine hydrochloride. For example, as the simulated body fluid, N a CI, N a H C0 3, N a 2 H P0 4, N a H 2 P0 4, KC I, KH C0 3, K 2 H P0 4, KH 2 P0 4, M _{g CI 2, C a CI 2} , N a 2 S0 4, that the N a F any compound selected from the like are dissolved in water. In addition, a compound containing calcium and a compound containing phosphorus are added. If necessary, HCI, (CH ₂ OH) ₃ CN H ₂ or the like can be added.

[0031] The composition of the simulated body fluid is as follows: N a +: 1 20 to 160 mM, K +: 1 to 20 mM, C a ²⁺ : 0.5 to 50 mM, H C0 ₃ _: 0.5 to 30 mM, HP 0 ₄ ² _: “! ~ 20 mM is preferred. For example, sodium ion concentration 1 47 mM, potassium ion concentration 5 mM, calcium ion concentration 7.5 mM, bicarbonate ion 4.2 mM, and hydrogen phosphate ion 4.2 mM, pH 7. Aqueous solution of 4 Can be exemplified as one of the preferred simulated body fluid compositions.

 [0032] (3. Method of mixing ceramic or its raw material after mixing substrate with hydrous solvent)

 In the step (A), for example, a water-containing solvent containing one or more water-soluble salts of magnesium and aluminum is mixed with a water-containing medium containing the base and an alkali metal salt. Specifically, for example, magnesium and aluminum nitrates are used as water-soluble salts, and sodium carbonate is used as an alkali metal salt. As a result, sodium carbonate becomes a precipitant, and magnesium and aluminum hydroxides are formed on the surface of the substrate.

 [0033] Step (B) is a step of adding an aggregating agent to the mixed liquid obtained in step (A) and stirring. In this step, the substrate on which the ceramic or its precursor is immobilized on at least a part of the surface is agglomerated by the aggregating agent. As a result, a solid body containing the substrate and the flocculant having ceramics or a precursor thereof immobilized on at least a part of the surface is formed.

 [0034] The flocculant added in the step (B) is preferably a water-soluble flocculant. Of the water-soluble flocculants, polymer flocculants are preferred. Examples thereof include polymers such as acrylamide, acrylic acid, and methacrylic acid, and those obtained by modifying at least a part of functional groups of these polymers. As long as it is a polymer flocculant, any type of anionic, nonionic, cationic, or amphoteric can be used, and any type of polymer flocculant can be selected depending on the pH of the added mixture. Since polymer flocculants other than the nonionic type contain a partial structure of ion pairs, an inorganic salt may remain when the flocculant is decomposed in step (D), and further washing may be required. Examples of ion pairs include sodium salts, potassium salts, chlorides, sulfates, and the like. From this point, a nonionic polymer flocculant is preferable. However, as is apparent from the amount of the flocculant used for the optical semiconductor particles, the amount of the remaining inorganic salt is not large, so that types other than the nonionic type can be used.

[0035] As the polymer flocculant, a polyacrylamide containing one or more compounds selected from the group consisting of acrylamide or a modified product thereof as a repeating unit. A system flocculant can be illustrated. Specifically, polyacrylamide, which is a polymer of acrylic amide, modified acrylic amide polymer, copolymer of acrylic acid and acrylic amide, copolymer of acrylic amide and modified acrylic amide, acrylic amide And a copolymer of dimethylaminoethyl methacrylate. The anionicity or cationicity of the flocculant is adjusted by post-processing the polymer or by the copolymerization ratio. Here, the modified acrylic amide is the substitution of the hydrogen atom of the amide group of the acrylamide with an alkyl group or an alkyl group having an ammonium salt / sulfonic acid group / hydroxyl group and a hydrophilic substituent. Examples are given. The form of the flocculant is not particularly limited, and any of powder, dispersion, base, emulsion or solution can be used. The addition method is not particularly limited, and any known addition method may be used.

 [0036] The amount of the flocculant used is set to 0. 0 based on the weight of the substrate contained in the mixed solution.

 It is preferably 1% by weight or more and 3% by weight or less, more preferably 0.5% by weight or more and 1.5% by weight or less. When the amount is not less than the above lower limit value, a sufficient agglomeration effect can be obtained, and when the amount is not more than the above upper limit value, the decomposition in the step (D) can be prevented from taking too much time and the productivity can be improved. Become. In addition, the effect of simplifying solid-liquid separation can be obtained.

 [0037] In the step (C), the solid obtained in the step (B) is recovered from the water-containing solvent. The solid matter recovered from the mixed solution contains a substrate having a ceramic or its precursor immobilized on at least a part of the surface and a flocculant. When recovered, it need not be composed of only these, and may contain a hydrous solvent, a neutralized salt, or the like. Further, the method for recovering the solid matter is not particularly limited. Known methods for separating solids and liquids may be applied, such as natural filtration by the weight of the water-containing medium, vacuum filtration, pressure filtration, centrifugation, and decantation.

[0038] In the step (D), the solid collected in the step (C) is heated to decompose the flocculant. By removing the decomposed flocculant, the optical semiconductor particles of the present invention can be obtained. Here, the flocculant is not limited to the case where it is completely removed, and a small amount of insoluble matter may remain. To decompose the flocculant, the flocculant must be decomposed. The solid is heated in the temperature range. At low temperatures, the flocculant tends to be insufficiently decomposed, and it takes a long time to decompose. When the temperature is high, the flocculant decomposes quickly, but the photo-semiconductor particles are easily deteriorated by heating. Therefore, the heating temperature is preferably 400 ° C. or more and 100 ° C. or less, and more preferably 500 ° C. or more and 80 ° C. or less. The heating time must be selected depending on the heating temperature, and is not particularly limited. For example, low temperature processing takes a long time, and high temperature processing takes a short time. In the case of heating at 600 ° C., 0.5 hours or more and 24 hours or less are preferable, and 1 hour or more and 18 hours or less are more preferable. Moreover, when the decomposition of the flocculant is based on an oxidative decomposition reaction, the decomposition can be promoted by increasing the oxygen partial pressure in the atmosphere.

 [0039] In the step (A), when a non-volatile compound is by-produced or a non-volatile compound is used, the non-volatile compound may be incorporated into the optical semiconductor particles as an impurity. In this case, it is necessary to clean the optical semiconductor particles. As a method for producing a non-volatile compound as a by-product, for example, base particles are dispersed in a nitric acid aqueous solution, and sodium silicate is mixed therewith, and the silicon compound is immobilized on the surface of the base. There is a method for preparing a mixed solution containing base particles. In this method, sodium nitrate formed as a neutralized salt corresponds to a nonvolatile compound. In addition, in the method using a non-volatile compound, a base particle is mixed in a solution in which calcium chloride and phosphate are dissolved as a ceramic raw material, and the compound of calcium and phosphorus is immobilized on the surface. There is a method for preparing a mixed solution containing the substrate particles. In this method, the remaining amount of calcium chloride and phosphate used corresponds to the nonvolatile compound.

[0040] In addition, the step (A) is a method using a strong sulfuric acid, a method using a sulfate as a by-product or using, or a method using a substrate, ceramics or a raw material of ceramics containing a sulfur compound. Sulfur compounds such as so ₄ minutes and SO ₃ minutes may be incorporated into the optical semiconductor particles and colored. In order to suppress or avoid this coloring, the content of the sulfur compound is 0.5% by weight as the weight of S atoms with respect to the weight of the metal compound photo semiconductor contained in the photo semiconductor particles. In the following, it is desirable that the content be 0.3% by weight or less, more preferably 0.2% by weight or less. Therefore, cleaning may be necessary to adjust the sulfur compound content.

[0041] When cleaning is required, when preparing the mixed solution in step (A), a method of removing impurities from the mixed solution using an ion exchange resin, or collecting solids in step (C) In this case, washing may be carried out by a method of passing a water-containing solvent through a cake made of solid matter formed on a filter, etc., independently of steps (A) to (D), You may implement as a manufacturing method including the process (E) which wash | cleans the solid substance containing the said base | substrate with which ceramics or its precursor was fix | immobilized to at least one part of the surface, and a flocculant. Process (E) includes process (B) and

(C), or between steps (C) and (D), if the ceramic substrate or its precursor is immobilized on at least a part of the surface, and a solid containing a flocculant And the solvent used for washing (hereinafter referred to as “washing solvent” where appropriate) can be easily separated, and can be easily washed. Cleaning is a process

Although it can be carried out after (D), a process for recovering the solid from the washing solvent and a process for drying the solid are necessary.

 [0042] The cleaning solvent is a hydrous solvent mainly composed of water. The washing solvent may include a water-soluble organic solvent having 1 to 4 carbon atoms among organic solvents classified into alcohols, ketones, ethers, or esters. When the step (A) is a step of by-producing water-soluble impurities such as inorganic salts, the solvent used for washing is preferably water.

[0043] The cleaning solvent may be adjusted to be acidic or basic in order to enhance the removal efficiency of impurities. For example, by adjusting the acidity with mineral acid or organic acid, the removal efficiency of cationic impurities such as alkali metals and alkaline earth metals can be enhanced. In addition, by adjusting the basicity with alkali metal hydroxide or ammonia, the removal efficiency of anionic impurities such as nitrate, chloride and sulfate can be enhanced. And the acid basicity of the washing solvent may be carried out only in either one, or the acidic and basic can be used in combination. Swing between acidic and basic In some cases, it may be washed. The pH of the washing solvent adjusted to be acidic or basic may be adjusted to any pH as long as the flocculant is not decomposed and exhibits a coagulation effect. When a nonionic polyacrylamide polymer flocculant is used, the pH is preferably in the range of 1 to 10, more preferably pH 2 to 8.

 [0044] The washing method includes, for example, a method in which the addition of the decant and the washing solvent is alternately repeated one or more times, a desalting treatment by ion exchange, a washing method in which redispersion in the washing solvent and filtration are alternately repeated one or more times, etc. It can be carried out by any known cleaning method. A flow cleaning in which the solvent is successively replaced is preferable, and an upward flow is more preferable. This is because it is possible to utilize the point that the solid matter (hereinafter referred to as “floc” where appropriate) in which coarse particles are formed by the effect of the flocculant exhibits a large sedimentation rate. Examples of such an apparatus include an apparatus in which a liquid mixture containing optical semiconductor particles and impurities is placed in a cylindrical container, water is supplied from the bottom of the container, and discharged from the top. Known devices such as thickeners and screw decanters can also be used. In addition, a flocculant may be added to re-form the flocs when the flocs break and fine particles are produced during the cleaning process.

 [0045] When washing with an upward flow of a hydrous solvent, the flow rate of the liquid in the portion separating the floc and the washing solvent is divided into a horizontal vector component and a vertical vector component. In this case, cleaning is performed by controlling the supply amount of the cleaning solvent so that the rising speed of the liquid as a vector component in the vertical direction is lower than the sedimentation speed of the hook. If the ascending speed exceeds the settling speed of the floc, the floc flows out from the washing device and cannot be washed. Although it is possible to set the ascending speed to 0, that is, to wash in a laminar flow with a washing solvent flowing only in the horizontal direction, the apparatus becomes complicated. Therefore, it is preferable that the rising speed is greater than 0 and equal to or less than the sedimentation speed of the floc.

[0046] When the washing solvent is supplied from the lower part of the floc precipitation, the precipitation layer becomes a resistance to the washing solvent, so that the ascending flow rate varies, and a local upflow may occur. In addition, bubbles generated in equipment piping and liquid pumps are supplied to the cleaning container, and the flock may rise in the cleaning container with the bubbles. The Therefore, if the rising flow rate approximates the floc sedimentation rate, washing can be processed in a short time, but the loss of the solid matter increases. On the other hand, if the ascending flow rate is too small, the loss of flocs can be suppressed, but it takes time for cleaning. Therefore, the rising flow rate is preferably 1% or more and 50% or less, and more preferably 3% or more and 25% or less, based on the floc sedimentation rate (100%).

[0047] When the photo-semiconductor particles produced in the present invention are photocatalysts having an Si oxide immobilized on the surface, the following can be exemplified.

 (a) a photocatalyst comprising: a substrate that is a metal compound photo-semiconductor; a silicon oxide film that substantially does not have pores covering the substrate;

 (b) The photocatalyst of (a), wherein the silicon oxide film is a fired film,

(c) The photocatalyst according to (b), wherein the silicon oxide film is a fired film obtained by firing at a temperature of 400 ° C or higher and 1000 ° C or lower.

 (d) the photocatalyst according to (a) to (c), wherein the alkali metal content is 1 ppm or more and 1 000 ppm or less,

 (e) In the measurement of the pore size distribution in the region of 20 to 500 angstroms by the nitrogen adsorption method, the photocatalyst according to (a) to (d) above, which has no pores derived from a silicon oxide film

(f) The photocatalyst according to any one of (a) to (e) above, wherein the supported amount of silicon per 1 m ^{2 of} surface area is from 0.1 mg to 2.0 mg.

 (g) The photocatalyst of (a) to (f) above, wherein silicon oxide contains an alkali metal,

 (h) The photocatalyst according to any one of (a) to (g), wherein the content of the sulfur compound is 0.5% by weight or less as a sulfur atom with respect to the weight of the photocatalyst.

 [0048] The photocatalysts (a) to (h) will be described in more detail. For example, the following are excellent in photocatalytic activity.

Examples of the alkali metal include lithium, sodium, potassium, rubidium, cesium, and francium. These alkali metals may contain only 1 type, and may contain 2 or more types. The metal strength metal content is preferably from 10 ppm to 1 000 ppm, more preferably from 10 ppm to 500 ppm. When the alkali metal content is within the above range, heat resistance is excellent, which is preferable. When an alkali metal is contained, a silicon oxide film with improved photocatalytic activity is formed.

 [0049] The amount of silicon supported is a calculated value calculated from the amount of silicon contained in the photocatalyst having the Si oxide immobilized on the surface and the surface area. The silicon loading is preferably 0.1 2 mg or more and 1.5 mg or less, more preferably 0.1 6 mg or more and 1. Omg or less. When the amount of silicon supported is not less than the above lower limit, the activation effect by the silicon oxide film is improved, and a sufficient photolytic activity effect is obtained. Further, when the amount of silicon supported is not more than the above upper limit value, a sufficient proportion of the substrate in the photocatalyst can be secured, and good photolytic activity can be obtained.

 [0050] From the viewpoint of preventing coloring of the photocatalyst, the sulfur compound is preferably 0.5% by weight or less, more preferably 0.3% by weight or less, and most preferably it is not contained.

 [0051] In the present invention, the presence or absence of pores derived from the silicon oxide film is determined by determining the pore volume distribution of the photo-semiconductor particles in which the ceramic is silicon oxide and the pores of the particles corresponding to the substrate of the photo-semiconductor particles. It can be determined by comparing the volume distribution. Specifically, it can be determined by the following methods (1) to (4).

 (1) Measure the nitrogen adsorption isotherm during the substrate desorption process,

 (2) Measure the nitrogen adsorption isotherm during the desorption process of optical semiconductor particles

 (3) Analyze the two nitrogen adsorption isotherms by the BJH (Ba r rt t — J o y ner — H a len d a) method to obtain an I o g differential pore volume distribution curve in the region of 20 to 500 angstroms.

(4) Comparing two I og differential pore volume distribution curves, the region where the I og differential pore volume of the photo-semiconductor particle is 0.1 m I / g or more larger than the I og differential pore volume of the substrate In the absence of pores, it is determined that the optical semiconductor particles are substantially free of pores, and in the case where a region larger than 0.1 ml / g exists, it is determined that the silicon oxide film has pores. Note that 0.1 ml / g or more is often caused by a measurement error of approximately 0.1 m I / g width in the log differential pore volume value in the pore distribution measurement by the nitrogen adsorption method. It is.

 Here, when the silicon oxide film has pores, the photolytic activity may be difficult to improve. The reason for this is not always clear, but the following reasons are presumed. In other words, light scattering and reflection on the silicon oxide film is likely to occur due to the presence of the pores, the amount of ultraviolet light reaching the substrate having photocatalytic activity is reduced, and the amount of holes and electrons generated by photocatalytic excitation is reduced. This is presumed to be due to Also, when coated with the same amount of silicon oxide, the one with pores is decomposed from the substrate with photocatalytic activity as a result of the thickness of the silicon oxide film being increased by the volume of the pores compared to the one without pores. It is presumed that sufficient photodegradation activity cannot be obtained because the physical distance from the target organic substance becomes large.

 [0053] Examples of the photocatalyst in which the calcium compound produced in the present invention is immobilized on the surface include the following. Here, the substrate is described as “titanium oxide particles” having excellent photocatalytic activity.

 (χ) Titanium oxide particles with calcium phosphate immobilized on at least a part of the surface,

 (y) The calcium phosphate apatite is immobilized on at least a part of the surface.

 Titanium oxide particles,

 (z) Titanium oxide particles in which calcium silicate is immobilized on at least a part of the surface.

[0054] In the photocatalysts (X) to (z), the calcium compound is effective as an adsorbent or a spacer. Such a photocatalyst has excellent adsorption performance, and deterioration of an organic base material (a base material made of an organic substance such as a resin) hardly occurs. Here, “deterioration of the organic base material” means that when the photocatalyst is added to the organic base material, the organic base material is decomposed and deteriorated by the decomposing power of the photocatalyst. The spacer effect of calcium compounds in the photocatalysts of (X) to (z) This is due to the structure in which the child does not directly contact the organic substrate. Therefore, it is difficult for the organic base material to be decomposed while maintaining the decomposing power of the photocatalyst.

 [0055] The amount of the calcium compound is preferably 0.5% by weight or more and 20% by weight or less, more preferably 3% by weight or more and 10% by weight or less, as the weight percent of Ca ions with respect to the total weight of the photocatalyst. . When the amount of the calcium compound is not less than the above lower limit, the effect as an adsorbent or a spacer can be sufficiently obtained. When the amount of the calcium compound is not more than the above upper limit value, the effect of suppressing deterioration of the organic base material can be obtained while maintaining the photocatalytic activity.

 [0056] The calcium compound may be of a single composition, but may be a mixture or composite of two or more compounds. For example, when calcium phosphate is immobilized, calcium carbonate generated based on carbon dioxide in the air may be immobilized together, or other inorganic ions may be included.

 [0057] The optical semiconductor particles obtained in the present invention have no difference in performance as compared with those produced without using a flocculant. Therefore, there are no particular restrictions on applications. For example, it can be blended as a UV shielding agent or pigment in the same manner as known ones in applications such as cosmetics, sunscreen creams, synthetic resins and paints. Further, as a photocatalyst, it can be used for a photocatalyst-containing body exhibiting functions such as air purification, water purification, deodorization, antibacterial, antifouling, and self-cleaning.

[0058] The photocatalyst-containing body includes an inorganic molded body containing a photocatalyst, an organic resin molded body containing a photocatalyst, a material having a photocatalytic coating film (the substrate may be either an inorganic compound or an organic compound), a photocatalyst paint, There are photocatalyst sprays, etc., which can be used in the following application fields and products: Ceramic filters and glass filters (air conditioners, refrigerators, humidifiers, dehumidifiers, cookers, air purifiers, dust collectors , Wastewater treatment equipment, etc.), paving asphalt, structural materials for RC buildings, humidity control building materials such as diatomaceous earth or zeolite, ceiling materials (rock wool, gypsum, etc.), tile joint materials, concrete blocks and concrete Rocking block, tile (exterior, paving, flooring, etc.), tile, sizing Materials, sealing materials, plastering materials such as building rubber, building stones, road stones such as paving stones, lanterns, garden stones, tombstones, rock baths, ceramics, tableware, window glass, vehicle glass (automobiles, trains, Aircraft, ships, etc.), lamp covers (fluorescent lights, lighting in tunnels, road lights, street lights, headlights, etc.), solar panel cover glass, glasses, furniture glass (such as cupboard glass doors and glass tables), Glass furniture (vases, etc.), mirrors (road mirrors, automobile mirrors, washstands, dental etc.), glass beads for water purification, exterior materials (for construction, automobiles, trains, aircraft, ships, etc.), metal roofs, Sash, wire mesh, antenna, faucet, mold for molding, handle, handle cover, shift knob, dash pad, bumper, train suspension leather, net shelf Liner, Meter panel, Helmet shield, Door knob, Flooring material, Tatami mat, Blind, Mouth screen, Furniture, Decorative plate, Sandwich, Bathroom material, Handrail, Tablecloth, Wallpaper, Electrical appliance (Refrigerator, Cooker , Hand dryers, personal computers, mice, keyboards, etc.), synthetic resin moldings, photocatalyst-containing masterbatches, fiber yarns, raw fabrics (woven fabrics, non-woven fabrics, etc.), clothing (overwear, pants, underwear, socks, etc.) , Bedding (sheets, futons, blankets, etc.), force—ten, goodwill, force pet, mask, handkerchief, towel, seat seat surface fabric, seat cover, vehicle mat, tent, rope, net, sofa, calligraphy paper, Shoji paper, newsprint, uncoated printing paper (high-grade printing paper, intermediate printing paper, low-grade printing paper, thin-leaf printing paper), Coated printing paper (art paper, coated paper, lightweight coated paper, etc.), special printing paper (color fine paper, other special printing paper), information paper (copy paper, carbonless paper, etc.), packaging paper (unexposed packaging) Paper, bleached wrapping paper, etc.), sanitary paper (tissue paper, dust paper, etc.), hybrid paper (industrial hybrid paper, household hybrid paper), artificial foliage plant, medical instrument, fuel cell electrode catalyst, dye sensitization Solar cell.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, at least a part of the surface prepared through a process corresponding to the process (B) of the present invention, ceramics or the like. A slurry composed of a substrate on which the precursor is immobilized and a solid containing a flocculant and a water-containing solvent is referred to as a “coarse particle liquid”. And in Examples 1 to 7 and Comparative Examples 1 to 4, those that do not describe the content of Al-strand metal in the optical semiconductor particles mean that the amount of Al-strand metal cannot be detected. Suppose that

 [0060] First, analysis methods used in Examples and Comparative Examples will be described.

 (i) Al strength metal content

 The alkali metal content was measured using a fluorescent X-ray analyzer (LAB CENTER XRE-1700, Shimadzu Corporation). The amount detected in this measurement was quantified using an atomic absorption photometer (Z-5000, Hitachi, Ltd.).

 (i i) Silicon content, Ca content, and P content

 Quantification was performed using a fluorescent X-ray analyzer (LAB CENTER XRE-1 700, Shimadzu Corporation).

 (i i i) Mg and A I content

 Quantification was performed using an I CP emission spectrometer (V I S TA_PRO, S I I). (i v) Specific surface area

 It was measured by a BET method specific surface area measuring apparatus (FlowSorb 2 2300, Shimadzu Corporation).

 (V) Crystallite diameter

 X-ray diffraction (XRD) measurements were performed and calculated using the Sierra suite.

[0061] (Example 1)

 (1 -A; Preparation of mixture 1)

Add 200 g of water and 81.7 g of 1 mo I / L nitric acid aqueous solution to a glass flask. Titanium dioxide (ST_01, Ishihara Sangyo Co., Ltd., water content 9% by weight, ratio table area 300 m ² / g, crystallite (Diameter 6 nm, Na content 1 400 ppm) 24.5 g was dispersed to prepare Liquid A. Water 1 00 g sodium silicate water solution beaker in one (S i 0 ₂ content of 29.1 wt%, N a ₂ 0 content of 9.5 wt%, JIS K 1 408 water-quenched glass No. 3 ") 1 Add 3 g and stir to make liquid B. Keep liquid A at 35 ° C and stir while liquid B at 2 m I / min. The mixture was added dropwise to obtain a mixture C. The pH of the mixture C at the end of the addition was 2.8, and the mixture C was stirred for 16 hours while maintaining the temperature at 35 ° C. The slurry concentration of Mixture 1 is 5.3% by weight.

 [0062] (1-B; Preparation of coarse particle liquid 1)

 Commercially available polymer flocculant Acofloc (registered trademark of Mitsui Chemicals Aqua Polymer) N 21 0 (Mitsui Chemicals Aqua Polymer Co., Ltd., nonionic, modified acrylic amide polymer) 1) 26mg of powder was added in three divided doses. The amount of the polymer flocculant used corresponds to 0.1% by weight. When stirring was continued, coarse particles were gradually formed, and the coarse particle liquid 1 was obtained by stirring for 15 minutes after completion of the addition of the polymer coagulant. In coarse particle solution 1, after stirring was stopped and allowed to stand for 30 minutes, a white floc settled on the bottom of the flask, and the supernatant liquid was slightly cloudy.

 [0063] (1-C; Preparation of optical semiconductor particle 1)

From the total amount of the coarse particle liquid 1, solids were recovered by vacuum filtration, and washed by repeating redispersion in 500 mL of pure water and vacuum filtration four times alternately. The washed solid was then placed in a magnetic dish and heated at 120 ° C for 3 hours in an air atmosphere using an electric furnace. The temperature was continuously raised to 600 ° C, and then kept at 600 ° C for 3 hours. After heating, the mixture was allowed to stand at room temperature to obtain 23.4 g of photo semiconductor particles 1. This optical semiconductor particle 1 was a white powder, the silicon content was 5.7 wt%, and the specific surface area was 187.1 m2 / g. Therefore, the amount of silicon supported per 1 m ² of the surface area of the optical semiconductor particle 1 was 0.31 mg. The photo-semiconductor particle 1 had a sodium content of 1 60 ppm.

 [0064] (Example 2)

 (2-A; Preparation of mixture 2)

 A liquid mixture 2 was obtained in the same manner as in Example 1 (1_A).

[0065] (2-B; Preparation of coarse particle liquid 2) A coarse particle liquid 2 was obtained in the same manner as in Example 1 (1_B) using the mixed liquid 2 except that 1 30 mg of the commercially available flocculant N 210 was used and charged in 12 portions. After the coarse particle liquid 2 was left stirring for 30 minutes, white floc settled at the bottom of the flask, and the supernatant liquid was clear. The amount of the polymer flocculant used corresponds to 0.6% by weight.

[0066] (2-C; Preparation of optical semiconductor particle 2)

 The entire amount of the coarse particle liquid 2 was transferred to a glass 50 Om L beaker and allowed to stand for 30 minutes, and then the supernatant liquid was decanted off. Next, washing was performed by repeating the following (a) to (d) five times.

 (a) Pure water 33 Om L was poured into the beaker.

 (b) Stir with a glass rod for 1 minute,

 (c) Left for 30 minutes,

 (d) The supernatant was decanted off.

The contents of the beaker were filtered under reduced pressure to recover the solid matter. The collected white solid was placed in a magnetic dish and heated at 120 ° C for 3 hours in an air atmosphere using an electric furnace. The temperature was continuously raised to 600 ° C, and then kept at 600 ° C for 3 hours. After heating, the mixture was allowed to stand at room temperature to obtain 24.1 g of photo semiconductor particles 2. This photo-semiconductor particle 2 is a white powder, with a silicon content of 5.7 wt%, a specific surface area of 195.99 m ² / g, a silicon loading of 1/29 m ² , and a sodium content of 1 It was 50 p pm.

[0067] (Example 3)

 (3-A; Preparation of mixture 3)

Add 555 g of water and 22.7 g of 60% nitric acid to a glass separable flask with a volume of 1.5 L. Titanium dioxide (ST_01, Ishihara Sangyo Co., Ltd., water content 9% by weight, specific surface area 300 m ² / g (Crystallite diameter 6 nm, Na content 1 400 ppm) 1 22. Og was dispersed to prepare a solution A. Beaker of water 232. 4 g sodium silicate solution in one (S i 0 ₂ content of 29 wt%, N a ₂ 0 content of 9.5 wt _^0/0, JISK 1 408〃 water glass No. 3 ") 67. Add 6 g and stir B liquid was used. While liquid A was maintained at 35 ° C. and stirred, liquid B was added dropwise at 3 ml / min to obtain liquid mixture C. The pH of mixture C at the end of dropping was 3.9. The mixture C was stirred for 16 hours while maintaining the temperature at 35 ° C. to obtain a mixture 3. The slurry concentration of mixture 3 is 11.1% by weight.

 [0068] (3-B; Preparation of coarse particle liquid 3)

 Example 1 except that 1/3 of the mixture 3 was used instead of the mixture 1 and that 21 8 mg of the commercially available flocculant N 2120 was used and was added in 23 portions. In the same manner as (1 _B), coarse particle liquid 3 was obtained. Coarse particle liquid 3 was stirred for 30 minutes and left to stand for 30 minutes. White floc settled on the bottom of the flask, and the supernatant liquid was clear. The amount of the polymer flocculant used corresponds to 0.6% by weight. In addition, when the flocs settled when stirring was stopped, the length at which the boundary between the sludge and the supernatant liquid descended in 1 minute was measured to determine the floc sedimentation rate. As a result, the sedimentation rate of floc was 3.7 cm / min.

 [0069] (3-C; Preparation of optical semiconductor particle 3)

The coarse particle solution 3 was transferred to a glass 50 OmL beaker and allowed to stand for 30 minutes. Thereafter, the supernatant was decanted off. Next, glass column tube (inner diameter 9 Omm, length 300 mm, lower end; 2-way cock included, upper end; 4 mm inner diameter glass tube can be held at any height and sealed except for inside the glass tube. ) Was fixed vertically, the bottom end cock was closed, the top end plug was opened, and the contents of the beaker were transferred into the column. After closing the stopper at the upper end and opening the cock at the lower end, pure water was supplied from the lower end at a rate of 1 OmL per minute for 5 hours, and drainage was discharged through the glass pipe at the upper end. At that time, the height of the glass tube was adjusted so that the liquid volume inside the column tube was 40 Om L. Note that the rising velocity of the liquid in the column tube, calculated from the supply rate of pure water and the inner diameter of the column tube, is 0.16 cm / min, which corresponds to 4% of the floc sedimentation rate. After 5 hours, the supply of pure water was stopped, and the contents of the column tube were filtered under reduced pressure to recover the solid matter. The collected white solid was placed in a magnetic dish and heated in an air atmosphere at 120 ° C for 3 hours using an electric furnace. The temperature was continuously raised to 600 ° C, and then kept at 600 ° C for 3 hours. After heating 42.5 g of photo-semiconductor particles 3 were obtained by standing until the temperature reached room temperature. This optical semiconductor particle 3 is a white powder having a silicon content of 6.1% by weight, a specific surface area of 209.8 m ² / g, a silicon loading of 0.29 mg per 1 m ^{2 of} surface area, and a sodium content of 1 It was 70 ppm.

[0070] (Example 4)

 (4-A; Preparation of mixture 4)

 One third of the mixture 3 was divided into 4 mixture.

[0071] (4-B; Preparation of coarse particle liquid 4)

 Same as Example 1 (1 _B) except that the mixture 4 was used instead of the mixture 1 and that 435 mg of the polymer flocculant N 210 was added in 36 portions. Coarse particle liquid 4 was obtained. The amount of polymer flocculant used is equivalent to 1.2% by weight.

[0072] (4-C; Preparation of optical semiconductor particles 4)

In the same manner as in Example 3 (3-C), except that the coarse particle liquid 4 was used instead of the coarse particle liquid 3, and that 600 ° C. was maintained for 5 hours, the optical semiconductor particles 4 were changed to 41 9 g was obtained. This photo-semiconductor particle 4 is a white powder with a silicon content of 6.4% by weight, a specific surface area of 212.3 m ² / g, and a silicon load of 0.30 mg per 1 m 2 of surface area, a sodium content. Was 200 p pm.

[0073] (Example 5)

 (5-A; Preparation of mixture 5)

Add 210 g of water and 2.8 g of 60% nitric acid to a glass flask. Titanium dioxide (ST_01, Ishihara Sangyo Co., Ltd., water content 9% by weight, specific surface area 300 m ² / g, crystallite diameter 6 nm, N a content 1 400 p pm) 20. 4 g was dispersed to prepare a solution A. In a beaker, 88.2 g of water and an aqueous solution of potassium silicate (manufactured by Wako Pure Chemical Industries, Ltd., Si 0 ₂ content 28% by weight) 1 1.7 g were added and stirred to make B solution. The liquid A was kept at 25 ° C. and stirred while the liquid B was added dropwise at 2 m I / min to obtain a liquid mixture C. The pH of mixture C at the end of the addition was 2.9. The mixture C was stirred for 16 hours while maintaining the temperature at 25 ° C. to obtain a mixture 5. Mixture 5 The slurry concentration of 5.6% by weight.

[0074] (5-B; Preparation of coarse particle liquid 5)

 Same as Example 1 (1 _B), except that mixed solution 5 was used instead of mixed solution 1 and that 109 mg of polymer flocculant N 2120 was added in 10 batches. Thus, a coarse particle liquid 5 was obtained. The amount of the polymer flocculant used corresponds to 0.6% by weight.

 (5-C; Preparation of photo-semiconductor particles 5)

In the same manner as in Example 2 (2-C) except that the coarse particle liquid 5 was used instead of the coarse particle liquid 2, 20.6 g of the photo semiconductor particles 5 was obtained. This optical semiconductor particle 5 is a white powder, silicon content 4.9% by weight, specific surface area 193.9 m ² / g, silicon loading 0.25 mg per 1 m ² surface area, sodium content 80 p pm, potassium content was 100 ppm.

[0075] (Example 6)

 (6-A; Preparation of mixture 6)

Add 230 g of water and 25.2 g of 1 mo I / L hydrochloric acid solution to a glass flask and mix with titanium dioxide (P_25, Nippon Aerosil Co., Ltd., ANATAZE: rutile ratio 8: 2, purity 99 (5%, specific surface area 50 m ² / g, no alkali metal detected) 22.4 g was dispersed to prepare Liquid A. 100 g of water in a beaker and sodium silicate aqueous solution (SiO ₂ content 29 wt%, Na ₂ O content 9.5 wt ⁰ / o, JISK 1 408 "Water Glass No. 3") 2.4 g was added and stirred to make B liquid. Liquid A was kept at 35 ° C. and stirred while liquid B was added dropwise at 2 m I / min to obtain liquid mixture C. The pH of the mixed solution C at the end of dropping was 2.9. The mixture C was stirred for 72 hours while maintaining the temperature at 35 ° C. to obtain a mixture 6. The slurry concentration of the mixed solution 6 is 5.9% by weight.

[0076] (6-B; Preparation of coarse particle liquid 6)

Mixture 6 was used in place of Mixture 1, and Acofloc (registered trademark of Mitsui Chemicals Aqua Polymer) N 1 00S (Nonion type, Mitsui Chemicals Aqua Polymer Co., Ltd.) instead of the commercially available polymer flocculant N 2100 Polyacrylamide) 1 1 5m The coarse particle liquid 6 was obtained in the same manner as in Example 1 (1-B), except that it was added in 10 batches. In the coarse particle liquid 6, after stirring was stopped for 30 minutes, a white floc settled on the bottom of the flask, and the supernatant liquid was transparent. The amount of polymer flocculant used corresponds to 0.5% by weight.

(6-C; Preparation of optical semiconductor particles 6)

 22.5 g of photo-semiconductor particles 6 were obtained in the same manner as in Example 2 (2-C) except that the coarse particle solution 6 was used instead of the coarse particle solution 2. This photo-semiconductor particle 6 is a white powder, with a silicon content of 1.3% by weight, a specific surface area of 52.9 m2 / g, a silicon loading of 0 25 mg per 1 m2 of surface area, and a sodium content of 40 ppm. Met.

[0077] (Example 7)

 (7-A; Preparation of mixture 7)

 A liquid mixture 7 was obtained in the same manner as in Example 6 (6-A).

 (7-B; Preparation of coarse particle liquid 7)

 In the same manner as in Example 6 (6-B), a coarse particle liquid 7 was obtained. After the coarse particle liquid 7 was left stirring for 30 minutes, a white floc had settled at the bottom of the flask, and the supernatant liquid was transparent. The amount of polymer flocculant used corresponds to 0.5% by weight.

[0078] (7-C; Preparation of optical semiconductor particles 7)

The coarse particle liquid 7 was filtered under reduced pressure to collect a solid. The collected white solid was put in a magnetic dish and heated at 120 ° C. for 3 hours in an air atmosphere using an electric furnace. The temperature was continuously raised to 600 ° C, and then kept at 600 ° C for 3 hours. After heating, the mixture was allowed to stand until the room temperature was reached, and 29.9 g of photosemiconductor particles 7 were obtained. This photo-semiconductor particle 7 is a white powder with a silicon content of 1.3% by weight, a specific surface area of 54.2 m ² / g, a silicon loading of 0.24 mg per 1 m ^{2 of} surface area, and a sodium content of 820 ppm. there were.

[0079] (Example 8)

(8-A; Preparation of mixture 8) Using simulated body fluids such as sodium chloride, sodium bicarbonate, lithium chloride, disodium hydrogen phosphate, calcium chloride, hydrochloric acid, and water, Na ion 147 mM, K ion 5 mM, Ca ion 7.5 mM, carbonated water An aqueous solution of pH 7.4 was prepared with a composition of 4.2 mM elementary ions and 5 mM hydrogen phosphate ions. Titanium dioxide (ST_01, Ishihara Sangyo Co., Ltd., water content 9% by weight, specific surface area 3 O Om 2 / g, crystallite diameter 6 nm) is added to 2000 g of this simulated body fluid. Stirring was continued at ° C for 8 hours. The slurry concentration at this stage is 0.5% by weight. Next, heating and stirring were stopped, and the mixture was allowed to stand at room temperature for 18 hours. As a result, a white precipitate was formed at the bottom, and the supernatant liquid was slightly turbid. After decanting off the supernatant, the precipitate was diluted with pure water to a total volume of 100 g. This was subjected to ultrasonic irradiation and stirring treatment for 1 hour, and the precipitate was redispersed to obtain a mixed solution 8. The slurry concentration of the mixed solution 8 is 10.0% by weight.

 (8-B; Preparation of coarse particle liquid 8)

 Example 1 (1 -B), except that the mixture 8 was used instead of the mixture 1 and that the commercially available polymer flocculant N 2120 was added in 57 mg, powdered in 5 portions. In the same manner, coarse particle liquid 8 was obtained. After the coarse particle liquid 8 was stopped stirring and allowed to stand for 30 minutes, white floc settled on the bottom of the flask, and the supernatant liquid was transparent. The amount of polymer flocculant used corresponds to 0.6% by weight.

 (8-C; Preparation of optical semiconductor particles 8)

 The coarse particle liquid 8 was transferred to a glass 20 OmL beaker and allowed to stand for 30 minutes, and then the supernatant liquid was decanted off. Next, the following (a) to (d) were repeated 5 times for washing.

 (a) Pure water 1 3 Om L was poured into a beaker,

 (b) stirred for 5 minutes with a glass rod,

 (c) Left for 30 minutes,

(d) The supernatant was decanted off. The contents of the beaker were filtered under reduced pressure to recover the solid matter. The collected white solid was placed in a magnetic dish and heated at 120 ° C for 3 hours in an air atmosphere using an electric furnace. Subsequently, the temperature was raised to 450 ° C, and then maintained at 450 ° C for 12 hours. After heating, the mixture was allowed to stand at room temperature to obtain 10.9 g of photo semiconductor particles 8. This photo-semiconductor particle 8 was a white powder, and contained 4.4 weight of Ca ( ⁰ / o) and 1.9 weight% of P by fluorescent X-ray analysis.

[Example 9]

 (9-A; adjustment of mixture 9)

After putting 450 g of water into a glass flask and dissolving 16.5 g of sodium carbonate decahydrate, titanium dioxide (ST_01, Ishihara Sangyo Co., Ltd., water content 9% by weight, specific surface area 300 m ² / g, Crystallite diameter 6 nm, Na content 1 400 p pm) 1 5.37 g was dispersed to prepare X solution. At this time, the pH of the solution X was 10.9. Next, 280 g of water, 6.39 g of magnesium nitrate hexahydrate, and 3.09 g of aluminum nitrate nonahydrate were placed in a beaker and stirred to make Y solution. Subsequently, the Y solution was added dropwise at 1 Om I / min while stirring the X solution to obtain a mixed solution Z. The pH of the mixed solution Z at the end of dropping was 9.2. The mixture Z was stirred for 20 hours while maintaining the temperature at 64 ° C. to obtain a mixture 9. The slurry concentration of the mixed solution 9 is 1.8% by weight.

[0082] (9-B; Preparation of coarse particle liquid 9)

 Divide the flocculant into 16 times, except that the mixture 9 was used instead of the liquid mixture 1 and that 150 mg of the polymer flocculant N2120 was added in 14 portions. The coarse particle solution 9 was obtained in the same manner as in Example 1 (1_B) except that the charged particles were different. In the coarse particle liquid 9, after stirring was stopped and left for 30 minutes, a white floc settled on the bottom of the flask, and the supernatant liquid was slightly white and cloudy. The amount of polymer flocculant used is equivalent to 1.1% by weight.

[0083] (9-C; Preparation of optical semiconductor particles 9)

15.1 g of photo-semiconductor particles 9 was obtained in the same manner as in Example 2 (2-C) except that coarse particle liquid 9 was used instead of coarse particle liquid 2. This light half Conductor particle 9 was a white powder and contained 2.0% by weight of Mg and 1.4% by weight of AI by ICP spectroscopy.

[0084] (Comparative Example 1)

 (10-A; Preparation of mixed solution 10)

 In the same manner as in Example 1, a mixed solution 10 was obtained. The mixture solution 10 remained cloudy even after stirring was stopped and left for 30 minutes.

 (1 0-B; Preparation of coarse particle liquid 10)

 For comparison, no flocculant was used, so the coarse particle liquid 10 was not prepared.

 (1 o-c; Preparation of optical semiconductor particles 10)

In the same manner as in Example 1 (1_C), 24.Og of photo semiconductor particles 10 was obtained from the total amount of the mixed solution 10. These optical semiconductor particles 10 are white powder, silicon content 5.4% by weight, specific surface area 190.4 m ² / g, silicon loading per 1 m ² surface area 0.28 mg, sodium content 1 It was 50 p pm.

[0085] (Comparative Example 2)

 (1 1 -A; Preparation of mixture 1 1)

 One third of the mixture 3 was divided into mixture 1 1. The mixture 11 remained cloudy even after stirring was stopped and left for 30 minutes.

 (1 1 -B; Preparation of coarse particle liquid 1 1)

 For comparison, no flocculant was used, so the coarse particle liquid 11 was not prepared.

 (1 1 -c; Preparation of optical semiconductor particles 1 1)

Instead of the mixed liquid 1, the mixed liquid 11 was used in the same manner as in Example 1 (1-C) to obtain 40.9 g of the optical semiconductor particles 11. This photo-semiconductor particle 11 is a white powder, with a silicon content of 6.2% by weight, a specific surface area of 218.6 m ² / g, a silicon loading per 1 m ^{2 of} surface area of 0.28 mg, and a sodium content of 1 80 p pm.

[0086] (Comparative Example 3) (1 2-A; Preparation of liquid mixture 1 2)

 In the same manner as in Example 5 (5-A), a mixed liquid 12 was obtained. Mixture 1 and 2 remained cloudy even after stirring was stopped for 30 minutes.

 (1 2-B; Preparation of coarse particle liquid 12)

 For comparison, no flocculant was used, so the coarse particle liquid 12 was not prepared.

 (1 2-C; Preparation of optical semiconductor particles 12)

19.5 g of the optical semiconductor particles 1 2 was obtained in the same manner as in Example 1 (1-C) using the mixed liquid 12 instead of the mixed liquid 1. The optical semiconductor particles 1 2 is a white powder powder, silicon content 4.8 wt%, specific surface area 1 86. 0 m ² / g, silicon supported amount per surface area of 1 m ² is 0. 26 mg, sodium content 60 It was ppm and the rhodium content was 90 p pm.

[0087] (Comparative Example 4)

 (1 3-A; Preparation of liquid mixture 1 3)

 In the same manner as in Example 6 (6-A), a mixed solution 13 was obtained. Mixture 13 remained cloudy even after stirring was stopped and left for 30 minutes.

 (1 3-B; Preparation of coarse particle liquid 1 3)

 For comparison, no flocculant was used, so the coarse particle liquid 13 was not prepared.

 (1 3-C; Preparation of optical semiconductor particles 1 3)

Instead of the mixed liquid 1, the mixed liquid 13 was used in the same manner as in Example 1 (1-C) to obtain 21.1 g of the optical semiconductor particles 13. This photo-semiconductor particle 13 is a white powder with a silicon content of 1.4% by weight, a specific surface area of 56.4 m ² / g, a silicon loading per 1 m 2 of surface area of 0.22 mg, and a sodium content of 40 p. It was pm.

[0088] (Comparative Example 5)

 (14-A; Preparation of mixture 14)

In the same manner as in Example 8 (8-A), a mixed solution 14 was obtained. Mixture 14 remained cloudy even after stirring was stopped for 30 minutes. (1 4-B; Preparation of coarse particle liquid 14)

 For comparison, no flocculant was used, so coarse particle liquid 14 was not prepared.

 (1 4-C; Preparation of photo-semiconductor particles 14)

 The mixed solution 14 was put into 10 centrifuge tubes at a rate of 1 O g, and each of the following (a) to (d) was repeated 5 times for washing.

 (a) In a centrifuge (Kokusan Co., Ltd., H-1 8), it was treated at 3000 rpm for 10 minutes to precipitate solids.

 (b) The supernatant was decanted away.

 (c) 10 g of pure water was added,

 (d) The solid was dispersed by ultrasonic irradiation and shaking.

 Next, the contents of the 10 centrifuge tubes were filtered under reduced pressure to recover the solid matter. The recovered white solid was placed in a magnetic dish and heated at 120 ° C. for 3 hours in an air atmosphere using an electric furnace. The temperature was continuously raised to 450 ° C, and then maintained at 450 ° C for 12 hours. After heating, it was allowed to stand until it reached room temperature to obtain 10.9 g of optical semiconductor particles 13. This photo-semiconductor particle 13 was a white powder and contained 4.1% by weight of Ca and 1.8% by weight of P by fluorescent X-ray analysis.

 (Comparative Example 6)

 (Preparation of 1 5-A; Mixture 1 5)

 A liquid mixture 15 was obtained in the same manner as Example 9 (9-A). Mixture 15 remained cloudy even after stirring was stopped and left for 30 minutes.

 (1 5-B; Preparation of coarse particle liquid 15)

 For comparison, no flocculant was used, so the coarse particle liquid 15 was not prepared.

 (1 5-C; Preparation of photo semiconductor particles 15)

Instead of the coarse particle liquid 1, 13.8 g of the photo-semiconductor particles 15 were obtained in the same manner as in Example 1 (1_C) by using the whole amount of the mixed liquid 15. This photo-semiconductor particle 15 is a white powder. Based on ICP spectroscopic analysis, Mg is 2.1% by weight, and 8 is 1.4. Contained ⁰ / o quantity.

[0090] (Example 1 0)

 <Evaluation of preparation>

 (1. Measurement of flow rate)

The liquid passing speed in the filtration treatment was measured by the following method. Coarse particle liquid 1-9 and mixed liquid 10-15 are diluted with water, part of the supernatant liquid is removed, or a centrifuge (Hokusan, H-18) is used. The slurry concentration was adjusted to 5 wt% by either method of treating at 3000 rpm for 3 minutes to settle the solids and then decanting off a portion of the supernatant. A glass filter holder for vacuum filtration (Advantech Toyo Co., Ltd., K GS-47, funnel volume 1 1 OmL, effective filtration area 9.6 cm ² ) with a membrane filter inside, 2 Om L inside A vacuum filtration device was prepared in combination with a vacuum container equipped with a measuring cylinder. At that time, it was installed so that the foot of the base of the holder pierced the mouth of the graduated cylinder so that the filtrate collected in the graduated cylinder. Next, the vacuum vessel was depressurized with an aspirator, and 30 mL of the sample solution was poured onto the top of the filter. Then, the time until 5 mL of filtrate was accumulated, that is, the time for 1 OmL to flow, was measured with the time when 5 mL of filtrate was accumulated as the start time. The measurement results are shown in Table 1 together with the substrate, the slurry concentration of the mixed solution, the ceramic raw material, and the amount of coagulant used in the preparation of each sample solution.

[0091]

1

 (2. Photodegradation performance evaluation of optical semiconductor particles)

 The photo-semiconductor particles 1 to 15 were suspended in a methylene blue aqueous solution, irradiated with light, and the methylene blue concentration in the liquid was quantified by spectroscopic analysis to test the photolysis activity. The test operation method is as follows.

 (Preparation of optical semiconductor particle suspension)

 45 g of methylene blue aqueous solution with a concentration of 40 X 10 0-6 mo I / L was weighed into a 1 O O c c polyethylene wide-mouthed bottle containing a fluororesin stirrer in advance. Next, 1 Omg of photo-semiconductor particles was added while stirring with a magnetic stirrer. Then, after stirring vigorously for 5 minutes, the stirring intensity was adjusted to such an extent that the liquid did not scatter and stirring was continued.

 (Preliminary adsorption treatment)

Starting from the moment the photo semiconductor particles were added, the stirring was continued for 60 minutes without light irradiation. After 60 minutes, 3. O cc of the suspension was collected and used as a sample before irradiation. (Photolytic treatment)

Standard suspension cell made of quartz (Tosoh_ Quartz Co., Ltd., outer dimensions 1 2.5 X 1 2.5 X 45 mm optical path width 10 mm, optical path length 10 mm, volume 4.5 cc) and stirred with a magnetic stirrer. Next, light was irradiated for 5 minutes from the outside / lateral direction of the spectroscopic cell. Light irradiation was performed through a quartz filter container filled with pure water using the light source device S X_UI 15 1 XQ (Usio Electric Co., Ltd., 15 OW Xenon short clamp) as a light source. The amount of irradiation light was 5.0 mW / cm ² when the highest luminance part was measured with an ultraviolet illuminance meter UVD-3650 PD (Usio Electric Co., Ltd., test wavelength 36 5 nm). After irradiation, the suspension in the spectroscopic cell was collected and used as a sample after light irradiation.

[0093] (Quantification of methylene blue)

 Membrane filter 1 (Toyo Roshi Kaisha, Ltd., DIMSIC—13 HP) was attached to an all plastic 5 cc syringe. The sample suspensions before and after the light irradiation were put into each, and extruded with Biston to remove the photo semiconductor particles. At that time, discard the first half of the filtrate and collect the latter half of the filtrate in a semi-micro mouth type disposable cell for analysis of visible light (made of polystyrene, optical path width 4 mm, optical path length 1 Omm, volume 1.5 cc). did. Then, using a UV-visible spectrophotometer (U V-2550, Shimadzu Corporation), the absorbance at a wavelength of 680 nanometers was measured, and the methylene blue concentration was calculated. The reason for discarding the first half of the filtrate is to avoid the influence of the phenomenon that the concentration of methylene blue is adsorbed on the membrane filter attached to the syringe and the concentration changes at the beginning of the flow. This is because, if about L is passed, the adsorption is saturated and the concentration of the sample solution can be measured correctly. The photodegradation activity is based on the initial concentration of methylene blue as the methylene blue concentration from the methylene blue concentration before the light irradiation, and as the methylene blue adsorption rate before the light irradiation as the methylene blue concentration after the light irradiation as the methylene blue decomposition rate. It is shown in Table 2.

[0094] (3. Determination of presence or absence of pores derived from silicon oxide film by pore distribution measurement) Photo-semiconductor particles 1-7, 10-1-13, and titanium oxide ST-01 and P_2 in the desorption process under liquid nitrogen (7 7 K) using autosoap (manufactured by Cantachrome) 5 nitrogen adsorption isotherms were measured. Titanium oxide was used after baking at 200 ° C. for 3 hours and drying.

 First, as a pretreatment, vacuum degassing at 100 ° C was performed.Next, the nitrogen adsorption isotherm of each sample was measured, and the results were analyzed by the BJH method to obtain an Iog differential pore volume distribution curve. Asked. Next, the presence or absence of pores derived from the silicon oxide film was determined. Specifically, the photo-semiconductor particles 1 to 5 are ST-01, and the photo-semiconductor particles 6 and 7 are P 1 25, and the Iog differential pore volume distribution curves are compared. The presence or absence of holes was determined. Figures 1-3 show I og differential pore volume distribution curves. The results are shown in Table 2.

[0095] [Table 2]

[0096] From Table 1, in Examples 1 to 9 using the flocculant, the ratio without using the flocculant Compared with Comparative Examples 1 to 6, it can be seen that the passing time is shorter. Therefore, when the method of this example is used, the photo semiconductor particles can be collected in a short time. Table 2 also shows that the same photodegradation performance of the photo-semiconductor particles is obtained in the examples and comparative examples regardless of the presence or absence of the flocculant. From the above, it has been shown that the production method of the present invention facilitates solid-liquid separation and does not affect the performance of optical semiconductor particles as an optical semiconductor.

Industrial applicability

 The production method according to the present invention facilitates solid-liquid separation when producing optical semiconductor particles in which ceramics are immobilized on the surface of a metal compound optical semiconductor and the performance is modified. Does not affect the performance. Therefore, it can be used for the production of optical semiconductor particles used as cosmetics, pigments, photocatalysts and the like.

Claims

The scope of the claims  [1] A method for producing optical semiconductor particles comprising a base that is a metal compound optical semiconductor and ceramics immobilized on at least a part of the surface of the base, wherein the ceramic is a compound different from the base. And a method for producing an optical semiconductor particle comprising the following steps (A) to (D):  (A) a step of mixing the substrate, the ceramic or its raw material, and a water-containing solvent to prepare a mixed solution containing the substrate and water on which the ceramic or its precursor is immobilized on at least a part of the surface;  (B) adding a flocculant to the mixed solution, stirring, and obtaining a solid body containing the base and the flocculant on which the ceramic or its precursor is fixed at least on a part of the surface;  (C) recovering the solid from the water-containing solvent,  (D) A step of decomposing and removing the flocculant by heating the solid to obtain photo-semiconductor particles.  [2] The photo-semiconductor particle according to claim 1, further comprising the following step (E) between the steps (B) and (C) or between the steps (C) and (D): Production method (E) A step of washing the solid body containing the substrate and the flocculant on which the ceramic or its precursor is immobilized on at least a part of the surface.  [3] The step (E) is based on the flow of the water-containing solvent, and the flow rate of the liquid in the portion separating the solid matter and the washing waste liquid is determined by the horizontal vector component and the vertical vector vector. When the water component is divided into torr components, washing is performed by controlling the supply amount of the hydrous solvent so that the rising speed of the liquid as a vector component in the vertical direction is slower than the settling rate of the solid matter. Item 3. A method for producing an optical semiconductor particle according to Item 2.  [4] The method for producing optical semiconductor particles according to claim 1 or 2, wherein the flocculant is a polymer flocculant. [5] The method for producing an optical semiconductor particle according to claim 4, wherein the polymer flocculant is a nonionic type. [6] The photo-semiconductor particle according to claim 4, wherein the polymer flocculant is a polymer compound containing, as a repeating unit, one or more partial structures selected from the group consisting of acrylamide and modified products thereof. Production method. [7] The photo-semiconductor particle according to any one of claims 1, 2, or 4, wherein the heating temperature in the step (D) is not less than 400 ° C. and not more than 100 ° C. Manufacturing method 8. The method for producing optical semiconductor particles according to any one of claims 1, 2, 4, or 7, wherein the substrate is made of titanium oxide. 9. The method for producing optical semiconductor particles according to claim 1, wherein the ceramic is made of silicon oxide.  [10] The step (A) force is selected from the group consisting of a hydrous solvent containing the substrate and a silicate, a hydrous solvent containing a silicate and the substrate, and a hydrous solvent containing the substrate and a hydrous solvent containing a silicate. 10. The method for producing photo-semiconductor particles according to claim 9, wherein the method is a step of mixing at least one set and maintaining the pH of the mixed solution containing both the substrate and the silicate at 5 or less.  [11] The silicon oxide is immobilized in a film shape on at least a part of the surface of the substrate, and the pore size distribution in the region of 20 to 50 Angstroms by nitrogen adsorption method The method for producing an optical semiconductor particle according to claim 10, wherein in the measurement, the film is a silicon oxide film having no pores. [12] The amount of silicon supported per 1 m ² of the surface area of the optical semiconductor particles is 0.1 mg or more.  The method for producing an optical semiconductor particle according to any one of Claims 9 to 11, which is O mg or less.  [13] The method for producing an optical semiconductor particle according to [11], wherein the optical semiconductor particle contains Al force metal in an amount of 1 ppm or more and 10:00 ppm or less. 14. The method for producing optical semiconductor particles according to claim 13, wherein the silicon oxide contains an alkali metal.  15. The method for producing optical semiconductor particles according to claim 8, wherein the ceramic is composed of a compound of calcium and phosphorus. 16. The optical semiconductor particle according to claim 15, wherein the ceramic is a ferrite. Manufacturing method.  17. The method for producing optical semiconductor particles according to claim 15, wherein the step (A) is a step of forming a compound containing calcium and phosphorus on the surface of the substrate using a simulated body fluid.  [18] The method for producing optical semiconductor particles according to [8], wherein the ceramic is a ceramic made of an oxide containing at least one of magnesium and aluminum as a constituent component.  [19] The method for producing optical semiconductor particles according to [18], wherein the ceramic is a mixture of an oxide of magnesium and aluminum, or a ceramic made of a composite oxide of magnesium and aluminum.  [20] The step (A) is a step of mixing a water-containing solvent containing at least one or more water-soluble salts of magnesium and aluminum with a water-containing solvent containing the base and the alkali metal salt. 9. The method for producing an optical semiconductor particle according to 8.  [21] The method for producing an optical semiconductor particle according to any one of [9], [15], and [18], wherein the optical semiconductor particle is a photocatalyst.