Stable nano titania sols and a process for their production

Stable nano titanium oxide sol and manufacturing method thereof

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] Not applicable.

[0003] Statement on Federally Funded Research and Development

[0004] Not applicable.

Technical field

[0005] The present invention generally relates to a stable concentrated nano-titanium oxide sol and its manufacturing method and use. For example, the present invention relates to a concentrated nano-titanium dioxide sol that is stable in a mild pH range (4.0 to 10.0) and its manufacturing method and use.

[0006] Background of the invention

[0007] Titanium oxide or titanium dioxide (Ti0₂) Usually exists in the form of either of the two main polymorphs-anatase or rutile-and has an average particle size of 150nm~250nm. Because of its high refractive index, negligible color and inertness, it can be used as a sunscreen agent in paints, paper, plastics, ceramics, inks, etc. Titanium dioxide with a smaller average particle size, such as an average particle size range of 1 nm to 150 nm, is called nano-titania. Nano-titanium oxide can be used in cosmetics, personal care products, plastics, surface coatings, self-cleaning because of its: i) translucency and photoprotective properties; ϋ) photocatalytic properties; and iii) electrical conductivity and high surface area. Surface and photovoltaic applications.

[0008] The focus around nano-titanium dioxide products supplied in powder form includes: i) difficulties in dispersing the product to the required size and ii) dust/handling issues due to the fineness of the nano-titanium oxide powder . Nano titanium dioxide products supplied in the form of stable and concentrated sols are also committed to solving these two key problems.

[0009] Stable water-containing nano titanium dioxide sols have been reported in all the literature. However, its production has been restricted to very low (< pH 2) or very high (> pH 10) pH regions or to low concentrations (< 300 gpl). [0010] In U.S. Patent Nos. 2, 44 & 683, a method is described in which the hydrous titanium dioxide is first neutralized, and then HC1 is used to make it into a gel to form a colloidal titanium dioxide sol. Then, the colloidal titanium dioxide sol is neutralized, dried and calcined at about 500°C~600°C, and then the calcined product is redispersed.

[0011] In US Patent Publication 2006/0110319, rutile nano-sized titanium dioxide can be prepared by hydrolysis of titanium tetraisopropoxide in an aqueous solution containing hydrogen peroxide and subsequent hydrothermal treatment at 50°C to 120°C. Sol.

[0012] U.S. Patent Publication 2009/0062111 describes a method for forming nano-sized titanium dioxide sol, the method includes precipitating aqueous titanium dioxide from a titanium isopropoxide solution and using α at a temperature of 70 ° C ~ 150 ° C -Suspension acid solizes the hydrous titanium hydroxide for a prolonged period of time.

[0013] US Patent Publication 2009/0061230 also describes a method for forming a stable nano-sized titanium dioxide sol by reacting a halide-containing titanium compound with water in the presence of a polyol.

[0014] In U.S. Patent No. 5,840,111, titanium dioxide nanoparticles are formed by adding a solution of sulfuric acid and titanyl sulfate to an alkaline reaction medium, and the nanoparticles are flocculated by adding a monobasic acid and then separated by filtration. It can prepare nano-sized titanium dioxide sol.

[0015] Similarly, it is still extremely desirable to produce highly stable alternative means of nano-sized titania sol, especially a means to produce highly stable concentrated nano-sized titania sol.

[0016] Summary of the invention

[0017] The present invention provides a method for manufacturing concentrated water-containing nano titanium oxide sol, the method comprising:

[0018] (a) Contacting the acidic nano titanium oxide sol with a dispersing agent and an alkalizing agent, the dispersing agent comprising water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicate 0 ; And at least one of, wherein the pH of the nano-titanium oxide sol after the contact is about 4.0 to about 10. 0; and

[0019] (b) The pH-adjusted nano titanium oxide sol is subjected to membrane filtration, preferably cross flow filtration or cross flow filtration under vibration, and membrane filtration is continued until the nano titanium oxide sol contains more than 300 g Ti.₂Nanoparticles/dm³ο

[0020] The present invention also provides a method for manufacturing concentrated aqueous nano-titanium oxide sol, the method comprising:

[0021] (a) Provide acidic nano titanium oxide sol;

[0022] (b) Contacting the acidic nano titanium oxide sol with a dispersing agent and an alkalizing agent, the dispersing agent comprising water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicic acid 0 ;with At least one of the salts, wherein the pH of the nano-titanium oxide sol after the contact is about 4.0 to about 10. 0; and

[0023] (c) The pH-adjusted nano titanium oxide sol is subjected to membrane filtration, preferably cross flow filtration or cross flow filtration under vibration, and membrane filtration is continued until the nano titanium oxide sol contains more than 300 g Ti.₂Nanoparticles/dm³ο

[0024] In another embodiment, during step (b) of the method described in paragraph [0013] or step (c) of the method described in paragraph [0014], preferably at the beginning of the nano-titania Before the sol is concentrated, the pH-adjusted nano-titania sol is contacted with a detergent to remove soluble salts from the nano-titania sol.

[0025] According to another embodiment, the nano-titanium oxide sol may be coated before, during or after any step of the above method.

[0026] The concentrated aqueous nano titanium oxide sol of the present invention is suitable for a variety of applications, including providing UV protection and photochemical degradation or passivation of pollutants.

[0027] Description of the preferred embodiment

[0028] In this and the following claims, many terms that will be understood as the following meanings are commented.

[0029] The term "nano-titanium oxide sol" refers to Ti0 having a particle size of less than 150nm, preferably less than 100nm₂A colloidal suspension of nanoparticles. The Ti. ? Nanoparticles can be anatase, rutile or amorphous material or their mixture.

[0030] The terms "cross-flow filtration" and "cross-flow filtration under vibration" refer to a filtration method in which a suspension of solid particles in a fluid medium is caused to flow tangentially across the surface of the membrane and at the same time subjected to easy suspension The pressure of a liquid fluid medium flowing through a membrane that is permeable to the fluid medium but impermeable to solid particles. The flow of the suspension across the surface of the membrane minimizes any excessive accumulation of solids on the surface of the membrane. The mechanical vibration of the membrane surface can be used to reduce clogging or fouling of the membrane. This method is described, for example, in U.S. Patent 4,952,317, the content of which is expressly incorporated herein by reference.

[0031] The present invention provides a method of manufacturing concentrated water-containing nano titanium oxide sol. In one embodiment of the present invention, the concentrated aqueous nano-titanium oxide sol is manufactured by a method including the following steps:

[0032] (a) Contacting the acidic nano titanium oxide sol with a dispersing agent and an alkalizing agent, the dispersing agent comprising water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicate 0 ; And at least one of, wherein the pH of the nano-titanium oxide sol after the contact is about 4.0 to about 10. 0; and

[0033] (b) The pH-adjusted nano titanium oxide sol is subjected to membrane filtration, preferably cross flow filtration or cross flow filtration under vibration, and membrane filtration is continued until the nano titanium oxide sol contains more than 300 g Ti.₂Nanoparticles/dm³ο

[0034] In another embodiment of the present invention, the concentrated aqueous nano-oxygen is produced by a method including the following steps

Titanium sol:

[0035] (a) Provide acidic nano titanium oxide sol;

[0036] (b) Contacting the acidic nano titanium oxide sol with a dispersing agent and an alkalizing agent, the dispersing agent comprising water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicic acid 0 ;with At least one of the salts, wherein the pH of the nano-titanium oxide sol after the contact is about 4.0 to about 10. 0; and

[0037] (c) The pH-adjusted nano-titanium oxide sol is subjected to membrane filtration, preferably cross-flow filtration or cross-flow filtration under vibration, and membrane filtration is continued until the nano-titanium oxide sol contains more than 300 g Ti.₂Nanoparticles/dm³ο

[0038] Basically all steps of the method of the present invention can be implemented at a temperature below 100 ° C, thereby making it simple and economical to implement an industrial device. The concentrated water-containing nano titanium oxide sol produced by the method of the present invention exhibits abnormal stability in a wide pH range, especially in a mild pH range of 4.0 to 10.0 (e.g., 6.0 to & 0) , Making the sol environment safe and easy to use. Moreover, the concentrated aqueous nano-titanium oxide sol does not exhibit agglomeration and therefore does not require a grinding step to exhibit excellent transparency. In addition, even when the nano titanium oxide sol is concentrated, it still has a low viscosity, making it particularly suitable for transportation and direct use.

[0039] According to an embodiment, an acidic nano titanium oxide sol is provided. The acidic nano titanium oxide sol can be provided by any means as long as it contains Ti0₂An acidic colloidal suspension of nanoparticles is sufficient. The Ti0 in colloidal suspension₂Nanoparticles can be made of anatase, rutile or amorphous Ti by any suitable method.₂be made of. Typical methods involve the hydrolysis of suitable titanium compounds such as titanium tetrachloride, titanyl sulfate or organic or inorganic titanates or the oxidation of oxidizable titanium compounds, for example in a vapor state.

[0040] In one embodiment, the TiO produced by the precipitation step in the sulfate method₂The acidic nano titanium oxide sol is manufactured. After precipitation, the obtained titanium oxide hydrate is filtered, washed to be free of impurities, and contacted with an aqueous alkali solution to form a suspension having about neutral pH. The sulfate ions are then removed from the neutralized suspension by filtration and washing. In one aspect, the filter cake obtained after filtration is washed until the SO content of the washed filtrate is less than 0.1 g/l (which can be determined by the titration of the chlorination solution). Then, the washed filter cake is slurried in water to produce an aqueous suspension of titanium oxide hydrate substantially free of sulfate ions, and then a strong monoprotic acid is used to adjust the pH to about 2.0 or less, preferably about 1.5 It can be solized to provide acidic nano titanium oxide sol.

[0041] Then, the acidic nano titanium oxide sol is contacted with a dispersing agent and with an alkalizing agent. The acidic nano titanium oxide sol can be contacted with the dispersing agent and the alkalizing agent in any order or in a combined manner.

[0042] According to one embodiment, the acidic nano titanium oxide sol is first contacted with a dispersant. The dispersant includes at least one of water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicate. In one embodiment, the water-soluble carboxylic acid is α-phosphoryl carboxylic acid. The α-phosphoric acid may include one, two or three carboxylic acid groups, and include, but are not limited to, lactic acid, phosphonic acid, malic acid, tartaric acid, mandelic acid, and citric acid. In another embodiment, the water-soluble carboxylic acid is beta-hydroxy carboxylic acid. In yet another embodiment, the water-soluble polycarboxylic acid is dicarboxylic acid or tricarboxylic acid. In other embodiments, the dispersant comprises one or more salts of the aforementioned acids. In yet another embodiment, the dispersant comprises a combination of the aforementioned acid and salt, as well as phosphate and silicate.

[0043] The acidic nano titanium oxide sol can be contacted with the dispersant for at least about 0.1 hours, preferably at least about 0.25 hours, and more preferably at least about 0.5 hours by any suitable means such as conventional mixing in a container Time period. In another embodiment, the acidic nano titanium oxide sol may be contacted with the dispersant for a period of less than about 24 hours, preferably less than about 12 hours, and more preferably less than about 3 hours. In yet another embodiment, the acidic nano titanium oxide sol may be contacted with the dispersant for a period of at least about 0.5 hours and at least less than about 3 hours.

[0044] The acidic nano titanium oxide sol is also contacted with an alkalizing agent. In one embodiment, after contacting with the dispersing agent, the acidic nano titanium oxide sol is contacted with the alkalizing agent. Examples of alkalizing agents include alkanolamines, preferably water-soluble alkanolamines such as isopropanolamine, and choline hydroxide. The time period during which the acidic nano-titanium oxide sol is in contact with the alkalizing agent is sufficient to adjust the pH of the acidic nano-titanium oxide sol to a period of time of about 4.0 to about 10.0 pH.

[0045] Then, the pH-adjusted nano-titanium oxide sol is subjected to membrane filtration, preferably cross-flow filtration or cross-flow filtration under vibration to obtain at least 300g Ti0₂Nanoparticles/dm³Of concentrated nano titanium oxide sol. In other embodiments, the nanosol is subjected to membrane filtration to obtain at least 500g TiO2 nanoparticles/dn?, preferably at least 550g TiO2 nanoparticles/dm³, More preferably at least 600g Ti02 nanoparticles/dm³And still more preferably at least 700gTiO2 nanoparticles/dm³Of concentrated nano titanium oxide sol. Preferably, the concentrated nano-titanium oxide sol has a viscosity of about OOlPas~about 0.2Pas at 20°C. The pH-adjusted nano titanium oxide sol used as a feedstock for membrane filtration generally has a solid content of less than about 350 g Ti. ?Nanoparticles/dm?. Thus, in one embodiment, the solid content of the pH-adjusted nano titanium oxide sol feedstock is at least about 100 g Ti02 nanoparticles/dm ~ less than about 350 gTi.₂Nanoparticles/dm³_o[0046] Optionally, at any time during the membrane filtration step, the pH-adjusted nano-titanium oxide sol is contacted with a detergent such as water, preferably deionized water, to remove a portion or substantially of the nano-titanium oxide sol. All soluble salts. In one embodiment, before concentrating the nano titanium oxide sol, during step (b) of the method described in paragraph [0021] or during step (c) of the method described in paragraph [0022] , Contacting the pH-adjusted nano titanium oxide sol with a detergent. In another embodiment, after concentrating the nano-titania sol, the pH-adjusted nano-titania sol is contacted with the detergent. The reduction of water-soluble salts from the nano-titanium oxide sol helps to produce a concentrated nano-titanium oxide sol with the desired low conductivity. In one aspect, during step (b) of the method described in paragraph [0021] or during step (c) of the method described in paragraph [0022], the nano-titanium oxide sol is contacted with the detergent for sufficient duration The electrical conductivity of the nano titanium oxide sol is reduced to a time period of less than 10 mS/cm, preferably less than 5 mS/cm, and more preferably less than 2 mS/cm.

[0047] In yet another aspect, optionally, by contacting the nano titanium oxide sol with a coating agent, the nano titanium oxide sol can be coated. The coating treatment can be performed before, during or after any step of the above method. In one embodiment, in step (a) of the method described in paragraph [0021] or in step (b) of the method described in paragraph [0022], the acidic nano titanium oxide sol is dispersed with After contacting the agent with the alkalizing agent, a coating treatment is performed. In another embodiment, during step (b) of the method described in paragraph [0021] or step (c) of the method described in paragraph [0022], preferably after the pH-adjusted nano-oxidation After the titanium sol is contacted with the detergent to remove the soluble salt from the nano titanium oxide sol, but before being concentrated, the coating treatment is performed. Suitable coating agents include alkaline or acidic coating agents, such as Inorganic oxide or hydrated oxide is coated on Ti0₂Those on the surface of nanoparticles. Typical inorganic oxides and hydrated oxides include one or more oxides and/or hydrated oxides of silicon, aluminum, titanium, aluminum, magnesium, zinc, lung, phosphorus, or tin. Relative to Ti0₂The weight of the nanoparticles, coated in Ti0₂Lwt%~50wt%. The amount of coating on the surface of the nanoparticles may be about 0.1 wt% to 50wt% of the inorganic oxide and/or hydrated oxide. Examples of alkaline coating agents include sodium silicate, potassium silicate, sodium aluminate, or mixtures thereof. Examples of acidic coating agents include aluminum chloride, aluminum sulfate, or mixtures thereof.

[0048] During the coating process, in order to ensure that the low ionic strength of the nano titanium oxide sol and the stability of the colloid are maintained during the process, a cation exchange resin can also be used. In this embodiment, the nano titanium oxide sol is contacted with an alkaline coating agent, preferably sodium silicate, and a cation exchange resin in a batch tank. Addition of sodium silicate and cation exchange resin

0. The rate is controlled so that the pH of the sol in the intermittent tank is maintained at about 4.0 to about 10.0. In another embodiment, the sol and the alkaline coating agent are passed through a column or carrier containing a cation exchange resin at a rate such that the pH of the effluent is maintained at about 4.0 to about 10.0. Any cation exchange resin is suitable for use, including those generally known, such as strong acid cation exchange resins containing sulfonic acid groups, weak acid cation exchange resins containing carboxylic acid groups, or mixtures thereof. In certain embodiments, if removal of the cation exchange resin is desired, techniques known in the art can be used to facilitate this removal.

[0049] During the coating treatment, an anion exchange resin may also be used. In this embodiment, the nano titanium oxide sol is contacted with the acidic coating agent and the anion exchange resin in a batch tank. 0. The addition rate of the acidic coating agent and the anion exchange resin is controlled so that the pH of the sol in the intermittent tank is maintained at about 4.0 to about 10.0. In another embodiment, the sol and acidic coating agent are passed through a column or carrier containing an anion exchange resin at a rate such that the pH of the effluent is maintained at about 4.0 to about 10.0. Any anion exchange resin is suitable for use, including those commonly known, such as strong basic anion exchange resins containing hydroxide or quaternary saddle groups, weakly basic anion exchange resins containing primary or secondary amino groups, or Their mixture.

[0050] The manufactured concentrated aqueous nano-titanium oxide sol exhibited exceptional stability and transparency. The currently known method involves drying the nano-titania sol (which leads to a part of the adhesion between the particles) and the subsequent grinding step. The method of the present invention avoids drying and grinding, but still provides a well-dispersed sol. Thus, in the preparation system containing the concentrated nano-titanium oxide sol produced by the method of the present invention, a nano-dispersion can be realized. Moreover, the present invention provides a sol in an improved physical form (ie, colloidal suspension to low-density adhesion powder), which greatly facilitates the subsequent processing and processing of the nano-titanium oxide sol.

[0051] The concentrated aqueous nano titanium oxide sol produced according to the present invention is suitable for use as a coating or in an article. For example, the concentrated nano titanium oxide sol can be used for: personal care products and cosmetic preparations such as sunscreens, moisturizers, color substrates, lipsticks, lipsticks, foot care products and ointments; coatings and mason preparations such as car paints, Wood coatings, architectural coatings, roofing granules >roofing shingles >building siding, floor, swimming pool surface and cement or concrete; used as a catalyst or photocatalyst or as a carrier for catalyst products; photovoltaic cells; Plastic parts, films and resin systems including agricultural films, food packaging films, molded automotive plastic parts and engineering polymer resins; rubber products including silicone rubber; used in products including polyamide, polyaramid and polyimide fiber Textile fibers in woven and non-woven applications and non-woven sheet products; glass products including architectural glass, automotive glass and industrial glass; flame retardants; and electronic components.

[0052] According to another embodiment, the concentrated aqueous nano titanium oxide sol can be used in a method of providing UV protection to the surface of a substrate. The method includes applying a concentrated coated aqueous nano-titanium oxide sol to the surface of a substrate as a film in the presence or absence of a binder medium. Various application techniques such as dipping, spraying, spin coating, dipping, brushing, and knife coating are used to apply the sol. Preferably, the concentrated coated nano-titanium oxide sol is applied to a thickness of about 0.001 mm to about 0.2 mm, the thickness being measured in a liquid state. The applied film then forms a protective coating on the surface of the substrate. Optionally, the film is dried. The substrates include, but are not limited to, textile fibers, furniture, paper, paving materials, tiles, cement, concrete, wood, ceramics, polymers, leather, asphalt, building exteriors, and glass. In another embodiment, the concentrated aqueous nano-titanium oxide sol is introduced into cosmetics and the mixture is applied to the skin surface as described above to provide UV protection.

[0053] According to another embodiment, there is provided a catalytic composition comprising the concentrated aqueous nano-titanium oxide sol produced by the method of the present invention. The catalytic composition containing the concentrated nano-titanium oxide sol can be used to help Yu Kuan

A range of reactions can be characterized by the conversion rate of the chemical reaction when the reacted reactants are contacted with the catalytic composition. In one embodiment, the catalyst composition is present on a support. Examples of carrier materials include glass, ceramics, metals, plastics, cement, concrete, asphalt, textiles, and paper. The support may be porous or non-porous. Examples of porous supports include fiber mats, zeolites, or porous membranes. The term "on the support" refers to when the catalytic composition is on at least a part of the surface of the support. With regard to the porous support, the term "on the support" also refers to the situation when the catalytic composition is additionally present in the pores of the support.

[0054] In one embodiment, the catalytic composition may be mixed with a reactant fluid and visible light radiation is used to provide a chemical reaction of one or more components of the reactant fluid. Then, the catalytic composition is recovered from the fluid and recycled for use in another part of the reactant fluid. Catalytic compositions can be used to replace common metal catalysts such as diamond, nickel, copper, gold, iron, paving, nickel, tongs, tongs, rake, copper, nails, silver, sawing, copper, and tin.

[0055] In another embodiment, the catalytic composition is present on the carrier, and the reactant fluid is in fluid contact with the carrier and the composition, and when light radiation is used, one or more components of the reactant fluid are provided chemical reaction. In this configuration, the catalytic composition can be exposed to a constant stream of fluid and there is no need to separate the catalytic composition from the fluid after performing the reaction. For example, in the case where the exhaust system is equipped with a visible or UV light source such as a fiber optic light source or an LED light source, the catalytic composition can be applied to a carrier such as an automobile exhaust system. During the operation of the automobile engine, the catalytic composition is irradiated to degrade the organic matter and other pollutants generated in the engine into environmentally acceptable substances.

[0056] In another embodiment, the catalytic composition may be present on surfaces in contact with various environmental contaminants or contaminants such as dust, grease, and other organic and inorganic contaminants and contaminants. The catalytic composition, optionally including a preparation of the catalytic composition, is applied to the surface and UV/visible light is used to irradiate the surface while allowing contaminants or pollutants to contact the surface. When exposed to UV/visible light, the surface becomes "self-cleaning" and degrades or passivates contaminants or contaminants. For example, self-cleaning glass may have a transparent or translucent coating of the catalytic composition applied to one or both sides of the glass. Then, when the glass is exposed to UV/visible light, the contaminants in contact with the glass are degraded. It is desirable for the self-cleaning glass to have a hydrophilic surface to rinse all remaining degradation products from the glass with water.

[0057] In another embodiment, the catalytic composition may be present on surfaces exposed to microorganisms such as bacteria and fungi and/or viruses. When exposed to UV/visible light, by destroying or inactivating microorganisms or viruses present on the surface, the surface becomes a "sterilized surface". For example, a surface in a residential, commercial or hospital environment may have a coating of catalytic composition applied to the surface. Then, when the surface is exposed to UV/visible light, the microorganisms and/or viruses in contact with the surface are destroyed or inactivated. Examples of surfaces that can be made as sterile surfaces include countertops, floors, walls, handles, switches, door handles, keyboards, telephones, and surfaces of medical equipment.

[0058] The catalytic composition can also be applied to a surface to provide temporary disinfection of the surface. For example, the catalytic composition can be incorporated into a cleaning composition. The cleaning composition may be in the form of a liquid, foam or lotion. Applying the cleaning composition to the surface and then exposing the surface to UV/visible light can destroy or inactivate the microorganisms or viruses present on the surface. This cleansing composition can be configured for application on the skin to provide a disinfectant personal care product.

[0059] The catalytic composition containing concentrated nano-titanium oxide sol can also be used for air and/or water purification. For example, mixing the catalytic composition with polluted air or water and using UV/visible light radiation. The contaminants in the air or water can be degraded into volatile substances or more easily separated from the air or water. For example, pollutants containing organic substances and halogenated substances can be degraded into carbon dioxide and halide ions, and then separated from air or water. In the case of air purification, contaminants such as N0 and N0₂Degradation alone or co-degradation with VOC can also lead to cleaner air and control air odor.

[0060] In another embodiment, a catalytic composition can be used for sensing gas. Because the electrical conductivity of Tit) nanoparticles varies with the chemical composition of their environment, this varying electrical conductivity makes it possible to remove Ti0₂Nanoparticles are used to measure a

Type and/or amount of one or more gases. Ti0 in the measurement environment₂Nano particles or containing Ti0₂The resistance of the nanoparticle material is compared with the resistance in the control environment. Use the amount and/or characteristics of the gas in the environment to correct the difference between the measured resistance and the control resistance. Examples of gases that can be identified and/or measured include hydrogen, carbon monoxide, hydrogen sulfide, and water. Preferably, a gas sensor containing a catalytic composition can be used to sense gas under environmental conditions.

[0061] In other embodiments, the catalytic composition can be used to produce hydrogen and oxygen from water. When water is irradiated with UV/visible light, the water containing the catalytic composition can be decomposed into hydrogen and oxygen by photolysis. This decomposition can also be carried out in photoelectrochemical cells with photoanodes containing quaternary oxides. It may be desirable to use a photo-electrochemical cell, as this enables separate collection of hydrogen and oxygen from the cell.

[0062] In another embodiment, the catalytic composition can be used to generate electricity from solar radiation, in particular, to sensitize TiO in a solar cell containing the catalytic composition and dye molecules.₂Nano particles. For example, when a dye molecule is excited by exposure to light, an electric current can be generated. The excited dye molecules migrate electrons into the conduction band of the nanoparticle, which conducts the electrons into the collector connected to the circuit with the load.

[0063] In yet another embodiment, the catalytic composition can be used in composite materials, including polymer composite materials, fibers, and non-woven fabric materials. For example, the catalytic composition and fibers can be incorporated into textile fibers. When exposed to UV/visible light, these fibers can degrade contaminants in contact with the fibers, resulting in self-cleaning fibers or disinfecting fibers.

[0064] In yet another embodiment, the catalytic composition can be used as a biologically active agent. In a water-containing environment, such as in organisms, Ti0 using UV/visible light radiation₂Nanoparticles can produce hydroxide ions (0H0, superoxide ions (. 2") and/or hydrogen peroxide. Ti() 2 nanoparticles that are exposed to UV/visible light and are in or in contact with cells at the same time thus produce The toxic environment damages or kills cells. Therefore, when delivered to tumor cells, the catalytic composition can be used as an anti-cancer agent. It is desirable to couple the catalytic composition to a targeting agent that is selectively absorbed by tumor cells. Light Laparoscopy is delivered to cells containing the catalytic composition, resulting in cell death or decreased cell growth or reproduction.

[0065] The present invention is further illustrated by the following embodiments, which are exemplary of the present invention. Unless otherwise specified, all parts and percentages in the examples are by weight.

Example

[0066] Example 1. Concentrated sulfuric acid is used to digest the ilmenite to obtain a digested cake. The digested cake is dissolved in water to form a crude liquid containing iron sulfate, titanium sulfate and a part of suspended insoluble matter. The iron in the form of trivalent iron is then chemically reduced and the liquid is filtered to remove insoluble materials. Then, the liquid is concentrated by vacuum treatment and hydrolyzed by heating and adding a nucleating agent to precipitate hydrous titanium oxide. The hydrated titanium oxide is separated from impurities by washing and filtering, and then the titanium oxide hydrate suspension is obtained by mixing the aqueous filter cake with deionized water. The titanium oxide hydrate suspension (pH <2) was then neutralized to a pH of 7.05 with ammonia water, filtered and washed with water to remove sulfate compounds, the filtrate washings had <100 ppm of SO and were then re-slurried in water . Then, the pH of the slurry was brought to pH 1.50 by adding hydrochloric acid and mixed for 30 minutes to produce an acidic nano titanium oxide sol containing 33% solids. Then, by mixing in a container for about 20 minutes, the acidic nano titanium oxide sol and citric acid (1.0g citric acid: 10. 0g Ti0₂) Contact. Then, the sol is contacted with monoisopropanolamine by mixing in the container for a period of time sufficient to adjust the pH of the sol to & 00. Then, by first contacting the sol with water, the pH-adjusted nano-titanium oxide sol is subjected to cross-flow filtration to remove soluble salts, so as to achieve a conductivity of 4.64mS/cm, and then the cross-flow filtration is continued until it is based on the water content. The total weight of the sol, each dn? The sol contains 673g Tit)? Nano particles. The prepared sol has a viscosity of 0.035 Pa s (measured at 19.3°C with a Brookfield viscometer using No. 2 spindle at 100 rprn). The typical particle size is 43nm, which is

Measured using CPS disc centrifuge. The pH of the sol was 8.2.

[0067] Example 2. At a dry film pigment volume concentration of 18.23%, the stable nano titanium oxide sol produced in Example 1 was incorporated into a semi-gloss acrylic emulsion. Then, the coating was applied to 125 On a um polyester film, the wet film thickness of the coating is 150 um. After curing, the resulting coating has an absorbance of 1.546 at a wavelength of 550 nm. In the same Ti0₂The comparative coating incorporating industrial anatase at a concentration has an absorbance of 2.489 at a wavelength of 550 nm.

[0068] Prediction Example A. According to Example 1, the acidic nano titanium oxide sol was obtained. Then, the acidic nano titanium oxide sol was contacted with citric acid by mixing in a container for about 30 minutes (l.Og citric acid: 10. Og Ti0₂) Ο Then, contact the sol with monoisopropanolamine by mixing in a container until the pH of the sol is about & 0. Then the Ti0 suspended in the pH-adjusted sol₂The nanoparticles are heated to 75°C and coated with silica by adding sodium silicate and cation exchange resin together (20wt% Si0₂At Ti0₂0. Above), so that the pH of the sol is maintained at about 5.0 to about 10.0. Then, by first contacting the sol with water, the silicon dioxide-coated Ti0₂The nano-particle nano-titanium oxide sol is subjected to cross-flow filtration to remove soluble salts and then continues to cross-flow filtration until the sol contains more than 30wt% coated Ti0 based on the total weight of the sol.₂Nano particles.

[0069] Prediction Example B. The concentrated water-containing nano-titanium oxide sol sample manufactured in Prediction Example A was prepared into a sunscreen composition containing the following components:

[0070]

<td>Component</td><td>%w/w</td>

<td>Butanediol</td><td>3</td>

<td>Ethanol</td><td>12</td>

<td>spices</td><td>Right amount</td>

<td>Silicate Liver</td><td>3</td>

<td>Kaolin</td><td>2</td>

<td>Nano titanium oxide sol (dilute with water to provide 12.5 g TiO₂/l)</td><td>80</td>

[0071] The gist of the above disclosure is considered to be exemplary and not restrictive, and the appended claims are intended to include all such changes, improvements, and other embodiments that fall within the true scope of the present invention. Therefore, to the maximum extent permitted by law, the scope of the present invention is determined by the broadest permissible interpretation of the following claims and their equivalents, and should not be restricted or limited by the above detailed description.