KR20030037050A - Titanium dioxide photocatalyst comprising an antimicrobial metallic component and method of preparation the catalyst - Google Patents

Abstract

PURPOSE: Provided are titanium dioxide photocatalyst with high antimicrobial action even when irradiation is not enough, and a method for fabricating the same. CONSTITUTION: The photocatalyst is composed of anatase or zinc oxide powder with 1-10 nm size and antimicrobial metal component such as Ag, Cu and Zn coated onto the powder. The method comprises the steps of (a) preparing antimicrobial metal compound by a coprecipitation process of antimicrobial metal component such as Ag, Cu and Zn and inorganic hydroxide, (b) dispersing the compound of the step (a) into water, thereby obtaining antimicrobial metal colloid, (c) preparing titanium peroxide, (d) mixing the antimicrobial metal colloid of the step (b) with the titanium peroxide, and obtaining crystalline oxide by hydrothermal reaction, and (e) coating porous inorganic oxides onto the crystalline oxide containing antimicrobial metal components by a three-step sol-gel process, thereby obtaining microcapsule type photocatalyst.

Description

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

By synthesizing colloids by synthesizing antimicrobial metals and titanium dioxide (anatase), which is a photoreactive catalyst, in the form of compounds or mixtures, they can express not only excellent photocatalytic performance but also strong antibacterial ability even in environments where the antibacterial ability or light irradiation is insufficient. An antimicrobial photocatalyst material can be prepared.

In particular, since it consists of a stable metal component, inorganic oxide component to the human body can be used as environmentally friendly photocatalyst antibacterial colloidal solution or photocatalyst antimicrobial coating agent.

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. However, the problems to be solved of the photocatalytic materials developed so far are summarized as follows.

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 the case of WO96 / 29375, a metal salt such as Ag, Cu, Zn, etc. is added to a suspension of photocatalyst particles prepared by the sol-gel method to form a photocatalyst after liquefying and coating or forming a photocatalyst coating. . In addition, in Japanese Patent Laid-Open No. 11-322524, an antimicrobial metal salt such as CuSO ₄ was added to TiO ₂ sol to coat the glaze layer, and then heat-treated at 300-900 ° C. to form an antimicrobial layer.

Representative metals exhibiting antimicrobial activity are Ag, 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. Japanese Patent Laid-Open No. 3-252308 is also possible in powder form, and is not suitable for obtaining a transparent film by adding to a colloid or a photocatalyst.

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. Crystalline photocatalyst particles can be obtained, and a porous inorganic oxide coating or microcapsule can be obtained by post-treatment to obtain a photocatalyst material having a more stable antimicrobial activity. 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 film that does not cause yellowing by adding a suitable binder. Microporous coating treatment 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. To provide this excellent ultra-fine (1nm to 100nm) inorganic antibacterial agent antibacterial enhanced photocatalyst colloid or photocatalyst powder.

1 is an antimicrobial test results according to Examples 1, 2 and 3 of the present invention

Figure 2 is an antimicrobial test photograph according to Example 1 of the present invention (strain 1)

Figure 3 is an antimicrobial test photograph according to Example 1 of the present invention (strain 2)

When light is irradiated on titanium dioxide, active oxygen and OH radical (radical) are generated on the photocatalyst to decompose and purify odorous substances by powerful redox effect. 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 electron gap of the valence band that absorbed more than the energy gap of 3.2 eV in the forbidden band is excited to move to the conduction band, and holes are made in the valence band and the movement is free. Therefore, when irradiated with ultraviolet (UV) light becomes an excited state, that is, an active state.

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.

Titanium dioxide can be produced through various processes. For example: 1. Hydrolysis of titanium sulfate (Ti (SO ₄ ) ₂ ), titanium sulfate (TiOSO ₄ ), titanium chloride (TiCl ₄ ), organic titanium compounds, etc. 2. Titanium sulfate And neutralization by adding alkali to titanium sulfate, titanium chloride, organotitanium compound, and the like, and 3. obtaining titanium chloride or the like by gas phase oxidation. Various methods have been attempted to improve the performance of the photocatalyst produced by the various methods described above. For example, by attaching at least one component selected from Ag, Cu, Pd, Fe, Ni, Cr, Co, Pt, Au, Li, Ca, Mg, Zn, Al, Rh, etc. to the surface of titanium oxide particles, The excitation can be facilitated to improve the performance of the photocatalyst. In particular, when Ag, Cu, Zn, etc. are added to the photocatalyst, antimicrobial activity can be maintained when sunlight or ultraviolet rays are not irradiated.

In order to add antimicrobial metal to photocatalyst sol or dispersion, there are various methods such as metal salt, compound, inorganic substance and ion exchange or surface deposition, but in this case, antimicrobial metal component is combined with metal hydroxide by coprecipitation method and it is within 1nm to 100nm. The present invention aims to produce an antimicrobial strengthening photocatalyst material that can be added to a photocatalyst sol and crystallized through hydrothermal reaction and microcapsule with porous inorganic oxide to coexist with photocatalyst particles in a more stable state. The present invention selects one or more components of titanium salts such as titanium sulfate, titanium sulfate, titanium chloride and zinc salt, zinc sulfate, zinc nitrate, and the like, which are alkaline ammonia water (NH ₄ OH), sodium carbonate (NaCO ₃ ), Neutralization titration method using sodium hydroxide (NaOH) and the like to stabilize the antimicrobial metals such as Ag, Cu, Zn with inorganic hydroxide to add a large amount to exhibit a strong antimicrobial activity. 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 method of coating TiO ₂ and SiO ₂ may be various, but a typical sol-gel process may be mentioned. Tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) as Precursor of SiO ₂ , Titanium Tetraisopropoxide (Ti (OC ₂ H ₅ ) ₄ ) as Precursor, Titanium alkoxide) of TiO ₂ , Titanium Tetraethoxide (Ti (OC ₃ H _{7) 4} ), Titanium acetate, etc., and alcohol, water such as methanol, ethanol, and isopropyl alcohol, 2-propanol, hydrochloric acid, nitric acid, etc. It can be obtained by hydrolysis by stirring, that is, by adding a silica sol, silica-titania sol, or an intermediate product made by the above-mentioned sol-gel method to an aqueous anti-catalyst containing an antibacterial metal, Decomposition reaction can occur to obtain a more stable antibacterial enhanced photocatalyst.

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 antimicrobial metal salt thereto, neutralize and titrate with an aqueous alkaline solution to produce an inorganic hydroxide containing an antimicrobial 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 solution 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 water dispersion treatment, a chemical method of colloidation using 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 ℃ When hydrothermal synthesis is carried out for 30 to 30 hours, an anatase type TiO ₂ colloid containing a stable antimicrobial metal component (mainly compound formation) is obtained. 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 antibacterial metal.

The TiO ₂ photocatalyst powder containing the antimicrobial metal component obtained as described above was added to a glass bead mill 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 wt%, more preferably about 0.8 to 20 wt%. It is then transferred to another container and silica coated. Here, the silica coating method is subjected to the fuzzy work using the reaction of hydrolysis using the sol-gel method. Tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ) was used as a precursor of silica, and one type of acid selected from hydrochloric acid (HCl), nitric acid (HNO ₃ ), and acetic acid (CH ₃ COOH) was used as a catalyst for the hydrolysis reaction. As a solvent of the hydrolyzate, one kind of water and a lower alcohol having 1 to 4 carbon atoms, that is, methyl alcohol, ethyl alcohol isopropyl alcohol, etc. were selected and used. Mix and stir the mixture of alcohol and ion-exchange water in another container, add it slowly to the Tetraethoxysilane solution and stir for 30 minutes to 3 hours while maintaining the temperature at about 30 ℃ to allow partial hydrolysis reaction. and heated to about 90 ℃ ℃ to evaporate half the Meter-Rate, while T and an antimicrobial metal-containing TiO ₂ photocatalyst dispersed colloid solution of the present invention in ion exchange water to maintain the 20 ℃ 40 ℃ 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 addition is completed to complete the silica coating antibacterial photocatalyst aqueous dispersion colloid. The solid content of silver is 1 to 30 parts by weight, and more preferably 5 to 20 parts by weight, The composition of the present invention is coated on a substrate surface, dried at room temperature, and then subjected to low temperature baking of 30 ° C to 200 ° C. The coating method is different depending on the shape of the substrate, but spin coating, spray coating, barcode, deep coating, etc. are used as a general method.

In addition, a surfactant may be used to impart stability of the dispersion when the hydroxide or oxide is dispersed. Surfactants that can be used include 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 Anionic surfactants such as alkyl ether sulfate, sodium acyl methyl taurate, sodium dodecyl benzene sulfonate, polyoxyethylene sorbitan alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene nonyl pentyl ether, polyoxyethylene lauryl ether, Nonionic surfactants, such as sorbitan stearate, polyether modified silicone, oxyethylene dodecylamine, polyester modified silicone, sorbitan laurate, polyoxyethylene octyl pentyl ether, sorbitan sesqui oleate, dimethyl alcohol betaine Amphoteric surfactants such as alkylglycine, imidazoline, alkyldimethylbenzyl chloride , Tetradecyldimethylbenzyl ammonium chloride, nuxadecyltrimethylammonium chloride, behenyltrimethylammonium chloride, alkylpropylenediamine acetate, octadecylamine acetate, tetradecylamine acetate, didecyldimethylammonium chloride, octadecyldimethylbenzyl ammonium chloride, etc. And cationic surfactants. The addition amount thereof is preferably about 0.1 part by weight to about 2 parts by weight.

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. Stabilization and secondary flocculation can be prevented. Secondly, silica can function as a binder to coat the antibacterial photocatalyst of the present invention on other kinds of surfaces.

(Example 1)

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

15 ml of titanium sulfate {Ti (SO ₄ ) ₂ } is slowly added dropwise while ice-cooling stirring 1000 ml of distilled or ion-exchanged water to maintain 0 ° C. After the dropping is completed, the mixture is slowly stirred and mixed for 10 minutes. While continuing to stir, 0.5 g of copper nitrate {Cu (NO ₃ ) ₂ .3H ₂ O} and 0.3 g of silver nitrate (AgNO ₃ ) were gradually added and stirred for 30 minutes. Then, ammonia water (NH ₄ OH, 0.5 mol / l) was slowly added dropwise to the mixed solution, and the mixture was stirred until the pH reached 7. This yields a milky white precipitate that stops stirring and holds for 12 hours. Subsequently, the precipitate is filtered and washed sufficiently with ion-exchanged water to obtain a titanium hydroxide gel containing Cu and Ag components. Ion-exchanged water is added thereto to make a mixed liquid having an appropriate concentration (about 0.9 wt% in terms of TiO ₂ ). Then, ammonia water (28%) was added thereto to pH 9.5, followed by dispersion treatment for 3 hours using a homo mixer to form colloids in the particulate state (1 nm to 100 nm). This creates a titanium hydroxide colloidal solution in which the Cu and Ag antibacterial metal components are immobilized, i.e., 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., followed by sufficient mixing for 10 minutes or more. Thereafter, ammonia water solution (NH ₄ OH, 0.5 mol / l) was prepared in another vessel, and the mixture was slowly added dropwise to the titanium tetrachloride solution, stirred, and neutralized titration was continued until pH 7 was obtained. As a result, a milky white precipitate product was stopped and the stirring was stopped for 12 hours. After that, the precipitate is filtered and washed with ion-exchanged water sufficiently to check the remaining amount of chlorine ions in a silver mirror reaction using an aqueous solution of silver nitrate. If there is no problem, add ion-exchanged water so that the total amount is 700 ml, and continue stirring for about 1 hour using an emulsifier to evenly disperse the precipitate in water. Thus, a Ti (OH) ₄ aqueous dispersion can be obtained. It is stirred while dropping 28% hydrogen peroxide (H ₂ O ₂ ) and 20 m 1 over about 30 minutes. Subsequently, when heated to 50 ° C. and completely dissolved in deep yellow color, the temperature was moved 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 produced, 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. Then, slowly add 300 ml of an aqueous titanium hydroxide dispersion having the antimicrobial metal immobilized thereto over 30 minutes, and then use 700 rpm using a propeller mixer. Continue stirring for 1 hour. In such a sufficiently mixed state, the mixture was introduced into an autoclave reactor and hydrothermal synthesis was performed at 200 ° C. for 3 hours while continuing propeller agitation at 800 rpm.

After cooling to room temperature, the product was filtered and washed with ion-exchanged water, and the product was confirmed to be anatase by using an X-ray diffractometer (XRD) and zinc (Zn) using an X-ray fluorescence analyzer (XRF). ) And the presence of 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, 7 ml of tetraethoxysilane {Si (OC ₂ H ₅ ) ₄ }, and 7 ml are added to the reaction vessel to which the cooling tube is attached, and the mixture is stirred for 10 minutes while maintaining at 30 ° C. A solution of 100 ml of ethanol, 20 ml of ion-exchanged water and 2 ml of HNO ₃ was slowly added thereto, and the mixture was kept at 30 ° C. for 1 hour while stirring was continued. Remove the cooling pipe, raise the temperature to 80 ℃ in the air, and increase the stirring speed to stop when half of the total capacity is reduced, and then cool it to room temperature and make it as 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 size is 2mmØ) and milled at 30 to 1000 to 3000 for 30 minutes. 100 nm inorganic oxide dispersion sol is prepared. Subsequently, the silica coating solution was added thereto and stirring was continued for 2 hours at a speed of 80 rpm. Thereafter, 200 ml of ion-exchanged water was added and the distillation under reduced pressure was carried out using a rotary evaporator to remove alcohol. Thus, a porous silica coated photocatalyst dispersion colloid 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} is added.

(Example 3)

Example 1 Copper nitrate in the _{{Cu (NO 3) 2 ·} 3H 2 O} is 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. Test strains were incubated with Staphylococcus aureus (Staphylococcus aureus) and Escherichia coli (E. coli) at 35 ° C. for 18 hours in the enrichment medium, and the number of bacteria was measured as shown in FIG. 1. And the antimicrobial test photograph using Example 1 was shown in FIG. 2 and FIG.

The antimicrobial metal-containing photocatalytic water dispersion colloid solution of the present invention has a feature that can further enhance the 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 antibacterial activity against bacteria and redox reaction to organic materials and super hydrophilicity on the surface of thin film. Its use is antibacterial, deodorization, antifouling, removal of harmful gas, self cleaning, etc. For this purpose, its use is extensive, and in particular, it is expected to be a more effective environmental purification material in terms of environment friendliness due to its high stability to the human body.

Claims (5)

Photocatalytic water dispersion or photocatalyst powder containing antibacterial metal component prepared by hydrothermal reaction The hydrothermal synthesis reaction of claim 1 is to induce a crystallization reaction of the structure of the dispersion mixture between the transparent titanium peroxide solution made from the reaction of titanium hydroxide and hydrogen peroxide and inorganic hydroxide containing antibacterial metal components at a temperature of 100 ℃ or more The antimicrobial metal of claim 1 is at least one of Ag, Cu, Zn, the inorganic hydroxide of claim 2 is at least one of Ti, Al, Zr, Ce, Zn hydroxide. The photocatalyst of claim 1 is at least one of titanium oxide and zinc oxide, and has a particle size in the range of 1 nm to 100 nm. The photocatalyst of claim 1 is porous coticized or microcapsule with silicon dioxide (SiO ₂ ) or titanium oxide.