KR100436240B1 - Titanium dioxide photocatalyst comprising an antimicrobial metallic component and method of preparation thereof - Google Patents

Abstract

The present invention relates to an antimicrobial metal component-containing titanium dioxide photocatalyst and a method for producing the same, which are capable of exhibiting a strong antimicrobial effect even in a state in which the irradiation amount of light as well as sunlight or ultraviolet rays is insufficient or absent. Process of preparing antimicrobial metal components such as Cu and Zn and inorganic hydroxide as a compound by coprecipitation method and dispersing them in water and colloiding, mixing titanic peroxide solution and colloidal solution and hydrothermal synthesis reaction By using a sol-gel process and coating the surface of the particles with a porous inorganic oxide to form a microcapsule to coexist titanium dioxide and antibacterial metal in a more stable state. So that the properties of both components can be expressed well at the same time. Relates to a titanium dioxide photocatalyst and a process for producing the same.

The photocatalyst prepared by the present invention is an antimicrobial-enhanced photocatalyst material prepared in the form of an aqueous colloidal solution or powder having a particle size of 1 nm to 100 nm or less.

Description

Titanium dioxide photocatalyst comprising an antimicrobial metallic component and method of preparation

The present invention synthesizes the antimicrobial metal component and the photoreactive catalyst material titanium dioxide (anatase) in the form of a compound or a mixture to form a colloid (colloid), not only excellent photocatalytic performance, but also strong antibacterial ability even in an environment in which antibacterial ability is enhanced or light irradiation is insufficient It relates to an antimicrobial photocatalyst capable of expressing and a method for producing the same.

The photocatalyst prepared according to the present invention is stable to the human body by synthesizing the containing metal in the form of an oxide, and can be used as an environmentally friendly photocatalyst colloid solution or photocatalyst antimicrobial coating agent by coating and microencapsulating with an inorganic oxide component.

Environmental purification by photocatalysts is expected as a future energy reduction technology in that it can utilize infinite light energy and does not emit secondary pollution by-products. In particular, strong redox effect on organic materials, super hydrophilicity and self-cleaning ability are excellent, and industrial products applying them are gradually increasing. Some of the challenges of the photocatalytic materials developed so far are summarized below.

1. The reaction rate is slow and the decomposition reaction is incomplete.

2. Low efficiency.

3. Only certain substances can be treated.

4. Removal of contaminants The degradation rate is slowed down.

5. The weaker the light irradiation, the lower the processing speed.

Various attempts have been made to overcome the above problems, for example, by adding metal components such as Pt, Au, Ag, Pd, Ru, Co, Ni, Fe, Cu, Cr to TiO ₂ photocatalyst particles more easily. The redox action can be induced to occur because the additive metal acts as a donor so that the electrons in the valence band can be easily excited. In addition, various improvements are being made, such as the addition of an adsorbent to improve the deodorizing performance, and the addition of antibacterial metals such as Ag and Cu to exhibit antibacterial activity even in the absence of light irradiation.

The photocatalyst may be classified into a solid phase method, a liquid phase method, and a vapor phase method. Among them, the most widely known method is a liquid phase method. Examples of the liquid phase method include precipitation by neutralization titration, coprecipitation, impregnation, and a sol-gel process using metal alkoxide as a precursor. In the neutralization titration method, titanium salts such as titanium chloride, titanium sulfate, and titanyl sulfate are used for ammonium water, sodium carbonate, and sodium hydroxide. It is neutralized with an alkali such as to produce titanium hydroxide (titanium hydroxide) and through the washing, drying and heat treatment process to produce an anatase (titanium oxide powder). This is known as a method of easily preparing powder and water dispersion. In addition, the sol-gel method uses titanium alkoxides such as titanium tetraisopropoxide and titanium tetrabutoxide as precursors to add alcohol, water, catalysts, etc. and to obtain titania sol through hydrolysis. It is easy and easy to obtain a pure sol of high purity and is used as a method to obtain a homogeneous thin film by coating (coating) and heat treatment to various kinds of carrier (substrate).

On the other hand, inorganic antibacterial agents using antibacterial metals such as Ag, Cu, Zn and the like are known to enhance the antibacterial ability by adding them. First, an inorganic antimicrobial agent (US Pat. No. 5,468,699) containing silver ions using a zeolite having a metal ion substitution ability is representative. In addition, the effect of silver salts on phosphate is included to prevent antibacterial and anti mold (Japanese Patent Laid-Open No. 2000-). 44415), and Japanese Patent Application Laid-Open No. Hei 3-205436 were prepared by dry heat treatment by zeolite ion exchange or by impregnating silica gel to prepare a powdered antimicrobial agent.

Japanese Patent Application Laid-open No. Hei 10-25435 coated silver and an equivalent antibacterial metal on the surface of a porous silica gel. Japanese Patent Laid-Open No. 3-287508 shows an antimicrobial composition by forming a film of aluminosilicate containing silver ions on the surface of alumina particles, and Japanese Patent Laid-Open No. 3-252308 contains silver ions on the surface of silica gel. A film of aluminosilicate was formed to obtain an antimicrobial composition. In addition, in the case of WO96 / 29375, a metal salt such as Ag, Cu, Zn or the like is added to a suspension of the photocatalyst particles prepared by the sol-gel method to be liquefied and coated or a photocatalyst coating is formed, and then a metal salt is applied to the photoreduction precipitate. This is the case. In addition, in Japanese Patent Application Laid-Open No. 11-322524, an antimicrobial layer was formed by adding an antimicrobial metal salt such as CuSO ₄ to TiO ₂ sol and coating the glaze layer, followed by heat treatment at 300-900 ° C. Cu and Zn. When these are added to the photocatalyst in the form of ionic metal salts or compounds, they may cause aggregation or defects in the coating film state, and thus they are subject to many restrictions in use. Particularly, in the case of Ag, the yellowing phenomenon is gradually changed due to the effect of ultraviolet rays when exposed to sunlight in the air there is a problem that the use is limited. Therefore, they are used in very small amounts, or by forming compounds with other substances. However, the compound has a disadvantage in that it is difficult to prepare a colloidal solution due to the larger particle size. In addition, when the silver component is used as an additive coating agent to the photocatalyst, it is difficult to exclude the possibility of discoloration except for a very small amount in the case of WO96 / 29375. It may cause inconvenience such as adding work process and deterioration of photocatalytic ability. In general, Ag is used as a product by replacing Ag ions with zeolite having a metal ion substitution ability and then drying and heat-treating processes, which causes discoloration when exposed to sunlight for a long period of time and particle size. The problem is that it is not possible to produce a waterborne colloidal solution, which becomes opaque when added to the coating. In the case of Japanese Patent Application Laid-Open No. 3-252308, it is possible only in powder form and is not suitable for adding a colloid or a photocatalyst to obtain a transparent film. When light is irradiated on titanium dioxide, active oxygen and OH radicals are generated on the photocatalyst, resulting in strong oxidation. It exhibits the property of decomposition and purification of odorous substances by the reducing action. Representative photocatalysts having an electrically semiconducting property include oxides such as TiO ₂ , ZnO, RuO ₂ , CoO, Ce ₂ O ₃ , Cr ₂ O ₃ , Rh ₂ O ₃ , V ₂ O ₅ , and sulfides such as ZnS and CdS. Can be mentioned. When ultraviolet rays of short wavelength (380 nm or less) are irradiated, they become excited and exhibit strong oxidizing power. Although there are many kinds of semiconductors showing similar behavior as described above, TiO ₂ is attracting attention because it is a chemically stable material and has excellent advantages as an optical semiconductor. Semiconductor energy bands have a valence band, a conduction band, and a gap between them. In the case of titanium oxide, the energy gap of the forbidden band is 3.2 eV, and electrons in the valence band that absorbed more energy are excited to move to the conduction band, and holes are made in the valence band. Free Thus, when irradiated with ultraviolet (UV) light, it becomes excited, that is, active. The electrons and holes move to the surface and combine with oxygen and hydroxyl groups to form radicals. In the case of titanium oxide, the oxidizing power of the hole is stronger, and mainly hydroxyl radicals oxidize organic substances and oxidize and decompose the carbon dioxide (CO ₂ ) and water (H ₂ O). In addition, it exhibits antibacterial activity even in the weak ultraviolet light amount that bacteria do not die.

Therefore, in the present invention, in order to combine the antimicrobial metal more stably with the photocatalytic particles, the antimicrobial metal component is bonded to the inorganic hydroxide by coprecipitation method, dispersed in the titanic acid solution, and the hydrothermal reaction is induced to produce a large amount of the antimicrobial metal component. It is possible to obtain crystalline photocatalyst particles, and to obtain a photocatalyst material having a more stable antimicrobial activity by a porous inorganic oxide coating or microcapsule by post-treatment. Such a photocatalyst can be used in the form of an aqueous colloidal form and powder, and can be used to obtain a transparent coating that does not cause yellowing by adding a suitable binder. Microporous coating of photocatalyst particles with silica or titania, that is, microcapsule of dispersed particles, does not cause discoloration or deterioration even after long-term exposure to sunlight, and maintains strong redox effect while maintaining strong redox effect. It is to provide an antimicrobial enhanced photocatalyst colloid or photocatalyst powder which is an excellent ultrafine (1 nm to 100 nm) inorganic antibacterial agent.

Figure 2 is a photograph showing the results of testing the antibacterial using the photocatalyst prepared in Example 1 of the present invention strain 1 (Staphylococcus aureus, ATCC 6538).

Figure 3 is a photograph showing the results of testing the antibacterial using the photocatalyst prepared in Example 1 of the strain 2 (Escherichia coli, ATCC 25922).

The inventors have combined the antimicrobial metal component with the metal hydroxide by coprecipitation method, prepared it into fine colloidal phase within 1 nm to 100 nm, added to the photocatalyst sol, and crystallization of the structure through hydrothermal reaction. By microencapsulation, an antimicrobial-enhanced photocatalyst material was prepared to coexist with the photocatalytic particles in a more stable state. The present invention is to prepare an antimicrobial metal component and inorganic hydroxide of Ag, Cu or Zn as a compound by coprecipitation method. Dispersing it in water and colloiding to prepare an antimicrobial metal-containing inorganic hydroxide sol; adding hydrogen peroxide to a titanium hydroxide (Ti (OH) 2) aqueous solution and heating to prepare a titanium peroxide solution and the antimicrobial metal-containing inorganic hydroxide After the sol was mixed, hydrothermal synthesis Preparing titanium dioxide crystals containing titanium oxide (TiO 2) and an antimicrobial metal component; microcapsule forming the surface of the antimicrobial metal component containing titanium dioxide with a porous inorganic oxide by using a sol-gel method The present invention relates to a method for producing a titanium dioxide photocatalyst containing an antimicrobial metal component. The present invention is also characterized in that the inorganic hydroxide is one of Ti, Al, Zr, Ce or Zn. The present invention is characterized in that the porous inorganic oxide is silicon dioxide (SiO ₂ ) or titanium oxide. In addition, the present invention utilizes at least one antibacterial metal salt of Ag, Cu or Zn stabilized with inorganic hydroxide, Coated with microporous inorganic oxide or microencapsulated to prepare a water-based colloidal solution with powder or 1-100nm particle size Relates to a titanium dioxide photocatalyst containing an antibacterial metal to the addition, the present invention is characterized in that the photocatalyst is in the pH 7 ~ 8 are prepared.

Titanium dioxide can be produced through various processes. For example, a method of hydrolyzing titanium sulfate (Ti (SO ₄ ) ₂ ), titanium sulfate (TiOSO ₄ ), titanium chloride (TiCl ₄ ), organic titanium compound, etc., titanium sulfate, titanium sulfate And neutralization by adding alkali to titanium chloride, organotitanium compounds, and the like, and gasification of titanium chloride and the like. In addition, recently, in order to improve the performance of the photocatalyst made by the above method, Ag, Cu, Pd, Fe, Ni, Cr, Co, Pt, Au, Li, Ca, Mg, Zn, Al or A method of improving the performance of the photocatalyst by attaching at least one component selected from Rh to facilitate electron photoexcitation has been attempted. Of these, when Ag, Cu, Zn, etc. are added to the photocatalyst, sunlight or ultraviolet rays are irradiated. When it can not be confirmed that the antimicrobial properties can be maintained. In order to add such an antimicrobial metal to a photocatalyst sol or dispersion, there are various methods such as metal salts, compounds, and inorganic ion exchange or surface deposition, but in the present invention, a method of combining an antimicrobial metal component with a metal hydroxide by coprecipitation method. The invention is selected from at least one component of titanium salts such as titanium sulfate, titanium sulfate, titanium chloride, and zinc salts such as zinc sulfate and zinc nitrate, and ammonia water (NH ₄ OH), sodium carbonate (NaCO ₃ ), and hydroxides. The neutralization titration method using sodium (NaOH), etc. stabilizes the antimicrobial metals such as Ag, Cu, Zn with inorganic hydroxides and adds a large amount so that the antibacterial activity can be exerted. In more detail, a predetermined amount of antimicrobial metal salts such as Ag, Cu, Zn, and the like are added to a solution of the metal salts immersed in ion-exchanged water or distilled water, and then sufficiently dissolved and mixed. Subsequently, the alkali component solution is slowly added to the mixture while ice-cooling and neutralized, and the mixture is stopped for 8 hours or longer to obtain a metal hydroxide containing an antibacterial metal. Subsequently, it is sufficiently washed with ion-exchanged water, and chloride is used to check the presence of residual chlorine ion by silver mirror reaction. Then, an appropriate amount of ion exchanged water is mixed and then dispersed in ion exchanged water using a high precision disperser. At this time, the solid content concentration is to be 10 parts by weight.

In particular, silver is easily discolored under the influence of UV rays or combines with chlorine (Cl) ions to form Ag chloride, and when combined with other ions or bases, the antimicrobial ability is significantly reduced and discolored. There are many limitations in using it. However, in the present invention, it is possible to prevent discoloration from ultraviolet rays by containing or combining titanium oxide or zinc oxide, which is a strong ultraviolet absorber, and by coating with TiO ₂ , SiO _2, etc. to influence physical and chemical external influences, namely ultraviolet rays and acid alkalis. By preventing the desorption caused by the Cl, ion and mechanical impact, the photocatalyst performance and the antibacterial ability can be imparted in a more stable state. Here, the TiO ₂ and SiO ₂ may be coated with various methods, but a typical sol-gel process may be mentioned. Tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) as a precursor of SiO ₂ , titanium tetraisopropoxide (Ti (OC ₂ H ₅ ) ₄ ), titanium as a precursor (Titanium alkoxide) of TiO ₂ Tetraethoxide (Ti (OC ₃ H ₇ ) ₄ ), titanium acetate, etc., are used to form alcohol, water, and sol such as methanol, ethanol, and isopropyl alcohol (2-propanol). It can be obtained through hydrolysis by adding zeric hydrochloric acid, nitric acid and the like and stirring for a certain time. That is, a more stable antimicrobial activity is achieved by adding a silica sol, silica-titania sol, or an intermediate product made to the sol-gel method of the photocatalyst aqueous dispersion containing antimicrobial metal to sufficiently hydrolyze the reaction. The enhanced photocatalyst can be obtained. Hereinafter, the configuration of the present invention will be described in more detail.

In the present invention, titanium sulfate (Ti (SO ₄ ) ₂ ), titanium sulfate (TiOSO ₄ ), titanium chloride (TiCl ₄ ), zinc sulfate (ZnSO ₄ · 3H ₂ O), zinc nitrate {Zn (NO ₃ ) ₂ · 6H ₂ O}, etc., select one species, add an antibacterial metal salt thereto, neutralize and titrate with an aqueous alkali solution to produce an inorganic hydroxide containing an antibacterial metal, and then disperse it to about 1 nm to 100 nm by physical or chemical methods to colloid In the first step of making a phase, one type is selected from titanium sulfate (Ti (SO ₄ ) ₂ ), titanium sulfate (TiOSO ₄ ), titanium chloride (TiCl ₄ ), and the like, and an aqueous alkali ammonia solution (NH ₄ OH), Hydrogen peroxide was added to a titanium hydroxide (Ti (OH) ₂ ) aqueous dispersion obtained by neutralization titration with sodium carbonate (NaCO ₃ ), sodium hydroxide (NaOH), and the like to prepare a titanium peroxide solution. The second antimicrobial metal hydroxide sol prepared in step 1 was added to the thus prepared titanium peroxide solution and dispersed therein, followed by hydrothermal synthesis at a temperature of 100 ° C. or higher to prepare a TiA ₂ and TiO ₂ crystals containing an antimicrobial metal. The dispersion obtained in step 2 and step 2 is coated with a porous inorganic oxide using a sol-gel method.

In the present invention, a buffer solution for neutralization titration was used by mixing ammonium hydroxide (NH ₄ OH) and ammonium chloride (NH ₄ Cl) in a 1: 1 ratio. The antimicrobial metal is selected from chloride, nitrate, sulfide, and acetate of the antimicrobial metal, added to the inorganic salt aqueous solution, mixed sufficiently, neutralized and titrated, and the metal hydroxide containing antimicrobial metal. Produced. In more detail, the alkali component is diluted in ion-exchanged water at a predetermined ratio to make an aqueous solution, and various components are added with ice-cooling stirring, and the aqueous alkali solution is slowly added dropwise so that the pH is 7 so that the metal hydroxide contains the antibacterial metal component. Form and hold for about 12 hours after stopping stirring. Thereafter, the mixture was sufficiently washed with ion-exchanged water, mixed with a predetermined amount of water, and treated with water (1 nm to 100 nm of sol). As an example of the water dispersion treatment, a chemical method of colloidating with an acid or an alkali, a ball mill, a glass bead mill, an attrition mill, or a homomixer is used. The pulverization or microdispersion treatment can be performed by physical methods.

In the next process, one of TiCl ₄ , Ti (SO ₄ ) ₂ , and TiOSO ₄ is selected to dissolve a certain amount in ion-exchanged water, and 1 in ammonia water (NH ₄ OH), sodium carbonate (HaCO ₃ ), sodium hydroxide (NaOH), and the like. Select the species and mix the NH ₄ OH and NH ₄ Cl in a 1: 1 ratio as a buffer solution to obtain Ti (OH) ₄ precipitate by neutralization titration and wash it sufficiently with ion-exchanged water. The residual reaction of chi ions was confirmed by wool reaction) and then dispersed in a predetermined amount of ion-exchanged water. Hydrogen peroxide (H ₂ O ₂ ) is added thereto, heated to 50 ° C., and stirring is continued to form a dark yellow transparent solution, titanium peroxide solution. Disperse the antimicrobial metal hydroxide in the particle size of 1nm to 100nm, using a reflux device attached to the cooling pipe for 3 hours at 80 ℃ to 100 ℃ to decompose hydrogen peroxide and then 8 hours at 100 ℃ to 200 ℃ Hydrothermal synthesis for 30 hours to obtain an anatase type TiO ₂ colloid containing a stable antibacterial metal component (mainly compound formation). After cooling to room temperature, the resultant was washed with water, dried at 100 ° C. to 120 ° C. for 5 hours, and heat treated at 450 ° C. for 3 hours to obtain an anatase-type TiO ₂ photocatalyst powder containing antimicrobial metal.

The TiO ₂ photocatalyst powder containing the antimicrobial metal component obtained as described above was added to a glass bead mill together with a predetermined amount of ion-exchanged water, and then rotated at a high speed at 1000 to 2000 rpm for 30 minutes for water dispersion. The solid content concentration of the aqueous dispersion thus obtained is adjusted to about 0.1 to 30% by weight, preferably about 0.8 to 20% by weight. Then transfer to another container and silica coating. Here, the silica coating method is a coating operation through the reaction of hydrolysis using the sol-gel method. First, tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) was used as a precursor of silica, and hydrochloric acid (HCl), nitric acid (HNO ₃ ), and acetic acid (CH ₃ COOH) were selected as a catalyst for the hydrolysis reaction. An acid of a species was used, and a solvent of the hydrolysis solution was selected from water and lower alcohols having 1 to 4 carbon atoms, that is, methyl alcohol, ethyl alcohol, isopropyl alcohol, etc. First, the predetermined amount of Tetraethoxysilane was mixed and stirred in alcohol, and the mixture of alcohol and ion-exchanged water was prepared in another vessel and slowly added to the tetraethoxysilane solution and stirred for 30 minutes to 3 hours while maintaining the temperature at about 30 ° C. The partial hydrolysis reaction is carried out and then heated to about 60 ° C. to 90 ° C. to evaporate half of the total amount, while for the TiO ₂ photocatalyst aqueous colloid containing the antibacterial metal component of the present invention in ion-exchanged water. The solution is stirred while maintaining the temperature between 20 ° C. and 40 ° C. The stirring is continued while the above hydrolysis reaction product is slowly added dropwise, and stirring is continued at the same temperature for about 3 hours after the dropping is finished. A dispersion colloid is completed, wherein the composition of the present invention has a solid content of 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, and the composition of the present invention is coated on a substrate surface at room temperature After drying, coating is possible by low-temperature firing at 30 ° C. to 200 ° C. The coating method depends on the shape of the substrate, but in general, spin coating, spray coating, barcode coating, and dip coating ( deep coating) and the like. In addition, a surfactant may be used to impart stability of dispersion in the dispersion of the hydroxide or oxide. As surfactant, sulfonic acid polyoxyethylene alkyl phenyl ether, fatty acid sodium soap, sodium dioctyl sulfosuccinate, alkyl sulfate, polycarboxylic acid, disodium lauryl polyoxyethylene sulfosuccinate, amide ether sulfate, sodium alkyl ether sulfate Anionic surfactants such as sodium acyl methyl taurate, sodium dodecyl benzene sulfonate, polyoxyethylene sorbitan alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene nonyl pentyl ether, polyoxyethylene lauryl ether, sorbitan stearate Nonionic surfactants such as latex, polyether modified silicone, oxyethylene dodecylamine, polyester modified silicone, sorbitan laurate, polyoxyethylene octyl pentyl ether, sorbitan sesquioleate, dimethyl alcohol betaine, alkyl glycine Amphoteric surfactants, such as imidazoline, alkyldimethylbenzyl chloride, tetradecyldi Cationic such as methylbenzyl ammonium chloride, nuxadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkyl propylene diamine acetate, octadecylamine acetate, tetradecylamine acetate, didecyldimethylammonium chloride, octadecyldimethylbenzyl ammonium chloride Surfactant etc. are mentioned, These addition amount is about 0.1 weight part-about 2 weight part suitably.

Two purposes of coating TiO ₂ photocatalyst and antimicrobial metal-fixed particles are to control the rapid oxidation reaction by coating the surface of TiO ₂ particles with porous silica or porous titania. To provide stabilization and the effect of preventing the secondary agglomeration phenomenon, and the second is to enable the silica to easily coat the antimicrobial photocatalyst of the present invention on the surface of another kind as a function of the binder.

(Example 1)

1. Preparation of inorganic hydroxide water dispersion which immobilizes antibacterial metal

15 ml of titanium sulfate {Ti (SO ₄ ) ₂ } was slowly added dropwise while ice-cooling stirring 1000 ml of distilled or ion-exchanged water at 0 ° C., followed by stirring and mixing for 10 minutes. While continuing to stir, slowly add 0.5 g of copper nitrate {Cu (NO ₃ ) ₂ · 3H ₂ O} and 0.3 g of silver nitrate (AgNO ₃ ) in order, stir for 30 minutes, and then add ammonia water (NH ₄ OH, 0.5) to pH 7. mol / l) was slowly added dropwise. This gave a milky precipitate product, where stirring was stopped and held for 12 hours. Subsequently, the precipitate was filtered and washed thoroughly with ion-exchanged water to obtain a titanium hydroxide gel containing Cu and Ag components. Add ion-exchanged water to make a mixed solution of the proper concentration (converted to TiO ₂ to about 0.9wt%), and add ammonia water (28%) to make the pH to 9.5, and then add a homomixer. Dispersion was carried out using for 3 hours to form a colloid in the particulate state (1 nm to 100 nm). This produced a titanium hydroxide colloidal solution in which Cu and Ag antibacterial metal components were immobilized, that is, in the form of a compound.

2. Preparation of TiO ₂ (anatase) Photocatalyst Powder Containing Antibacterial Metal

10 ml of titanium tetrachloride (TiCl ₄ ) is slowly added dropwise while ice-cooling stirring 1000 ml of distilled or ion-exchanged water to maintain a temperature of 0 ° C., and the mixture is mixed for at least 10 minutes, and ammonia water solution (NH ₄ OH, 0.5 mol / l) was prepared, and then neutralized titration was continued until the solution was slowly added dropwise to the titanium tetrachloride solution and stirred to pH 7. As a result, when a milky white precipitate was obtained, the stirring was stopped and maintained for 12 hours. The precipitate was filtered and washed with ion-exchanged water sufficiently, and then the remaining amount of chlorine ions was confirmed by a silver mirror reaction using an aqueous solution of silver nitrate. If there was no abnormality, ion-exchanged water was added so that the total amount was 700 ml, and stirring was continued for about 1 hour using an emulsifier to uniformly disperse the precipitate in water. Thus, an aqueous solution of Ti (OH) ₄ was obtained, and 20 ml of 28% hydrogen peroxide (H ₂ O ₂ ) was added dropwise over about 30 minutes, stirred, and heated to 50 ° C. to dissolve to a completely transparent dark yellow color. Warmed to 80 ° C. and stirred at 100 rpm to 500 rpm for 1 hour while maintaining 80 ° C. using a propeller mixer. At this time, a considerable amount of hydrogen peroxide is decomposed to generate and remove oxygen bubbles, and at the same time, a dark yellow transparent solution is formed, which is a colloidal solution of several nm size with titanium peroxide solution. Add ion-exchanged water to 900 ml, and then stir slowly while maintaining at 30 ° C., and slowly add 300 ml of an aqueous titanium hydroxide dispersion having the antimicrobial metal immobilized there over 30 minutes, and again at 700 rpm for 1 hour using a propeller mixer. Stirring was continued. The mixture was introduced into an autoclave reactor in a sufficiently mixed state and hydrothermal synthesis reaction was carried out at 200 ° C. for 3 hours while stirring was continued with a propeller stirrer at 800 rpm.

After cooling to room temperature, the mixture was filtered and washed sufficiently with ion-exchanged water. The product was then identified by X-ray diffractometer (XRD) to confirm that the dispersed particles were anatase, and X-ray fluorescence analyzer (XRF) was used. The presence of zinc (Zn) and silver (Ag) component was confirmed. Subsequently, the resultant was dried at 100 ° C. for 8 hours and then heat treated at 450 ° C. for 3 hours to prepare an antimicrobial metal-fixed TiO ₂ photocatalyst powder.

3. Porous Silica Coating

200 ml of ethanol and 7 ml of tetraethoxysilane {Si (OC ₂ H ₅ ) ₄ } were added to the reaction vessel to which the cooling tube was attached and stirred for 10 minutes while maintaining at 30 ° C., 100 ml of ethanol, 20 ml of ion-exchanged water, and HNO ₃ The mixed solution of 2 ml was slowly added and maintained at 30 ° C. while continuing stirring for 1 hour. The cooling tube was removed, the temperature was raised to 80 ° C. in the air, the stirring speed was increased, and when half of the total capacity was reduced, the mixture was stopped and cooled to room temperature to obtain a silica coating solution.

On the other hand, after mixing the antimicrobial metal immobilized TiO ₂ photocatalyst powder and 300ml of ion-exchanged water, it is added to a glass bead mill (glass bead is 2mmØ) and milled at 1000 to 3000rpm for 30 minutes to obtain a particle size of 10 An inorganic oxide dispersion sol having a thickness of about 100 nm was prepared. The silica coating solution was added thereto, stirred for 2 hours at a speed of 80 rpm, 200 ml of ion-exchanged water was added, and the alcohol was removed by distillation under reduced pressure using a rotary evaporator to remove alcohol. A containing photocatalyst dispersed colloidal solution was obtained.

(Example 2)

Example 1 Copper nitrate in the _{{Cu (NO 3) 2 ·} 3H 2 O} 1g and silver nitrate (AgNO ₃₎ of nitric acid in place of 0.3g of zinc _{{Zn (NO 3) 2 ·} 6H 2 O} 2g and copper nitrate Cu {( 1 g of NO ₃ ) ₂ .3H ₂ O} was added.

(Example 3)

Example 1 Copper nitrate in the _{{Cu (NO 3) 2 ·} 3H 2 O} 1g and silver nitrate (AgNO ₃₎ was added only silver nitrate (AgNO ₃₎ 0.5g to 0.3g instead.

(Example 4)

The antimicrobial test was done as follows. Staphylococcus aureus (ATCC 6538) at 46-fold increase in strain 1 (1.5 ± 0.3) X10 ⁵ / ml, and strain 2 at 42-fold increase in (1.3 ± 0.3) X10 ⁵ blank Example 1 Example 2 Example 3 Strain 1 Early strain 1.5 X 10 ⁵ 1.5 X 10 ⁵ 1.5 X 10 ⁵ 1.5 X 10 ⁵ 18 hours later 6.9 X 10 ⁶ <10 6.8 X 10 ² <10 Strain 2 Early strain 1.3 X 10 ⁵ 1.3 X 10 ⁵ 1.3 X 10 ⁵ 1.3 X 10 ⁵ 18 hours later 5.5 X 10 ⁶ <10 4.7 X 10 ² <10 In addition, the antimicrobial test photographs using Example 1 are shown in Figs.

The antimicrobial metal-containing photocatalyst aqueous dispersion colloidal solution of the present invention has a feature that can further enhance photocatalytic activity and exhibit a strong antimicrobial activity even in a state in which light irradiation is insufficient. The colloidal state is stable for a long time and can prevent the deterioration or discoloration of the contained antibacterial metal. It has strong antimicrobial activity against bacteria and redox reaction against organic materials and super hydrophilicity on the surface of thin film. It is expected to be a more effective environmental purification material in terms of environment-friendliness due to its wide range and high stability to the human body.

Claims (10)

delete delete delete delete delete Preparing an antimicrobial metal-containing inorganic hydroxide sol by preparing at least one antimicrobial metal component of Ag, Cu, or Zn and an inorganic hydroxide as a compound by coprecipitation, and dispersing it in water to colloidate it; Titanium hydroxide (Ti (OH) ₂ ) Hydrogen peroxide was added to the aqueous dispersion and heated to prepare a titanium peroxide solution, and the antimicrobial metal-containing inorganic hydroxide sol was mixed and then hydrothermally synthesized to form titanium dioxide (anatase). Preparing titanium dioxide crystals containing TiO ₂ ) and an antibacterial metal component; A method of preparing a titanium dioxide photocatalyst containing an antimicrobial metal component comprising a step of coating the surface of the particles with a porous inorganic oxide to the microcapsule by using a sol-gel method. 7. The method of claim 6, wherein the inorganic hydroxide is a hydroxide of one of Ti, Al, Zr, Ce, or Zn. 7. The method of claim 6, wherein the porous inorganic oxide is silicon dioxide (SiO ₂ ) or titanium oxide. Using at least one antibacterial metal salt of Ag, Cu or Zn stabilized with an inorganic hydroxide, the surface is coated with a porous inorganic oxide or microencapsulated to prepare a water-soluble colloidal solution having a powder form or 1 to 100nm particle size Titanium dioxide photocatalyst containing an antibacterial metal component. 10. The titanium dioxide photocatalyst of claim 9, wherein the photocatalyst has a pH of 7 to 8.