Stable nano titania sols and a process for their production

The present disclosure primarily relates to stable concentrated sols of titanium nanodioxide and methods for their manufacture and use. For example, the present disclosure relates to stable concentrated sols of titanium nanodioxide in the range of mild pH values ​​(4.0 - 10.0) and methods for their manufacture and use.

PRELIMINARY INFORMATION [0002] Titanium dioxide, i.e. titanium dioxide (TiO₂), is generally available for sale in one of the two major polymorphs as anatase or rutile, and the average particle size is 150 nm to 250 nm. Due to the high refractive index, the minimum color and inertness is useful as an opacifier for paints, paper, plastics, ceramics, inks, etc. Titanium dioxide with a smaller average particle size, e.g. in the average particle size range of 1 nm to 150 nm, is referred to as titanium nanodioxide. Titanium dioxide is used in cosmetics, personal care products, plastics, surface coatings, self-cleaning surfaces and photovoltaic systems due to: i) translucence combined with photoprotective properties; ii) photocatalytic properties; and iii) conductive properties combined with a large surface area. [0003] Problems associated with products containing titanium dioxide powders supplied in powder form include: i) difficulties in dispersing products to a suitable size; and (ii) problems related to pollination and handling resulting from the degree of fragmentation of powdered titanium nanodioxide. The product containing titanium nanodioxide supplied as a stable, concentrated sol would solve both of these important problems. and (ii) problems related to pollination and handling resulting from the degree of fragmentation of powdered titanium nanodioxide. The product containing titanium nanodioxide supplied as a stable, concentrated sol would solve both of these important problems. and (ii) problems related to pollination and handling resulting from the degree of fragmentation of powdered titanium nanodioxide. The product containing titanium nanodioxide supplied as a stable, concentrated sol would solve both of these important problems.

[0004] Permanent aqueous sols of titanium nanodioxide have been described many times in the literature. However, their production is limited to very low (<pH 2) or very high (> pH 10) pH ranges or to low concentrations (<300 g / l).

[0005] In pat. No. 2,448,683 describes a method in which hydrated titanium dioxide is first neutralized and then subjected to peptization with HCl, whereby a colloidal sol of titanium dioxide is obtained. This colloidal titanium dioxide sol is then neutralized, dried and calcined at a temperature in the range of about 500 ° -600 ° C, and then the calcination product is again dispersed.

[0006] In public pat. No. 2006/0110319 produces titanium dioxide solubility in the form of rutile nanometer size by hydrolysis of titanium tetraisopropoxide in an aqueous solution containing hydrogen peroxide, followed by hydrothermal treatment at 50 ° -120 ° C.

[0007] Publ. stalemate. No. 2009/0062111 describes a process for the preparation of a nanoscale titanium dioxide sol that precipitates hydrated titanium dioxide from a titanium tetraisopropoxide solution and peptizes this hydrated titanium dioxide with α-hydroxycarboxylic acid at 70 ° -150 ° C for a long time.

[0008] Publ. stalemate. No. 2009/0061230 also describes a method for producing a stable sol

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The nano-sized titanium was reacted by reacting a halide-containing titanium compound with water in the presence of a polyol.

[0009] In pat. No. 5,840,111, a sol of titanium dioxide of nanometer size is obtained by adding a solution of sulfuric acid and titanyl sulfate to a basic reaction medium, whereby titanium dioxide nanoparticles are obtained, flocculation of these nanoparticles by addition of monobasic acid and subsequent isolation of the flocculation product by filtration.

[0010] EP 0518175 relates to the preparation of a preparation suitable for the production of an inert sol metal oxide containing 35-75% by weight of one or more metal oxide or metal oxide hydrate and 15-45% by weight of one or more hydroxycarboxylic acid and / or acid derivatives hydroxycarboxylic stabilizers.

[0011] US 2819177 relates to a process for preparing an aqueous colloidal dispersion of a colorless, negatively charged titanium oxide, comprising acidifying a suspension of an aqueous monohydrate titanium dioxide substantially free of sulphate ion to a pH below 5 with an inorganic monobasic acid followed by a charge change on the colloidal particles obtained to the opposite in by changing the pH to a value of from about 5 to about 11 by means of a particular alkalizing agent.

[0012] EP 1052225 describes a method for preparing an inert colloidal sol of titanium dioxide with high stability in the neutral range, capable of producing a colorless transparent coating even after drying at room temperature. It is obtained by mixing an acid sol of titanium dioxide containing 50 to 100 parts by weight of colloidal titanium dioxide particles and 5 to 50 parts by weight of a titanium ion chelating agent with 1 to 50 parts by weight of a basic substance comprising at least one of alkali metal compounds and amine compounds and optionally by adjusting the pH of the liquid mixture to a value of 5 to 10 or adjusting the pH of the liquid mixture to a value of 6 to 10, and then performing a deionization process of the mixture,

[0013] WO 2009/030880 describes a method for purification of a pigment comprising washing said pigment with water containing less than 100 ppm by weight of the sum of dissolved solids and with a microbial contamination of less than 100 colony forming units per ml.

[0014] EP 1544256 describes a method for reducing the chemical activity and photoactivity of titanium dioxide nanoparticles comprising adding a thickening agent, e.g. citric acid, to an aqueous suspension of titanium dioxide nanoparticles and subjecting said aqueous suspension to a source of aluminum oxide, thereby forming titanium dioxide nanoparticles treated with aluminum oxide. In one embodiment, the particles are treated with a source of silicon dioxide, e.g. a sodium silicate solution. The nanoparticles of this invention can also be treated with a source of silicon dioxide and a source of aluminum oxide. The obtained nanoparticles can be silanized.

[0015] Accordingly, alternative methods for producing very stable volumetric di-oxide sols are still very desirable, and in particular, methods for producing very stable concentrated nanol-based titanium dioxide sols.

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EP 2 477 947 B1

SUMMARY [0016] The claimed invention discloses a process for the preparation of a concentrated aqueous sol titanium nanocentrol comprising:

(a) contacting the acid sol of the titanium nanodioxide with a dispersing agent containing at least one of the water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicate and with an alkalizing agent, wherein the pH of the sol titanium nanodioxide after contact it remains in the range of about 4.0 to about 10.0; and (b) subjecting the sol of the titanium nanodioxide with a pH-corrected membrane filtration, preferably cross-flow filtration or crossflow vibratory filtration, and further membrane filtration until the sol titanium nanodioxide contains more than 300 g of TiO nanoparticles₂ on dm³.

[0017] In one embodiment, the method of making the concentrated aqueous sol titanium nanodioxide comprises the step of providing an acid sol of the titanium nanodioxide;

and then carrying out the following stages:

(a) contacting said acid sol of the titanium nanodioxide with a dispersing agent containing at least one of the water-soluble carboxylic acid, a water-soluble carboxylic acid salt, a water-soluble polycarboxylic acid, a phosphate or a silicate, and an alkalizing agent, wherein the pH of the sol of the nanodioxide sol. the titanium on contact remains in the range of from about 4.0 to about 10.0; and (b) subjecting the sol of the titanium nanodioxide with a pH-corrected membrane filtration, preferably cross-flow filtration or crossflow vibratory filtration, and further membrane filtration until the sol titanium nanodioxide contains more than 300 g of TiO nanoparticles₂ on dm³.

[0018] In another embodiment, the pH adjusted titanium nitol sol may be contacted with the washing agent in step (b) of the process, preferably before concentrating the sol of the titanium nanodioxide, to remove the soluble salts from this sol titanium nanodioxide.

[0019] According to another embodiment, this sol titanium nanodioxide may be subjected to a coating process before step (b) or during step (b) after contacting the pH corrected titanium nitic acid oxide with a washing agent to remove soluble salts from this sol titanium nanodioxide, but before concentrating this sol titanium nanodioxide.

[0020] The concentrated aqueous sol of titanium nanodioxide according to the present disclosure is suitable for various applications, such as providing protection against ultraviolet radiation and degradation or photochemical deactivation of impurities.

[0021] The claimed invention also relates to a concentrated aqueous sol titanium nanodioxide containing more than 300 g of TiO nanoparticles.₂ on dm³wherein said sol can be obtained by preparation according to the above method.

[0022] The claimed invention also relates to a coating or article comprising this concentrated aqueous sol

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Titanium nanodioxide.

[0023] The claimed invention also relates to a catalytic composition comprising a concentrated aqueous sol titanium nanodioxide containing more than 300 g of TiO nanoparticles₂ on dm³wherein said sol can be obtained by preparation according to the above method.

The claimed invention also relates to a method of protecting a substrate surface against ultraviolet radiation comprising: applying a concentrated aqueous sol titanium nanowiut peroxide to the surface of a substrate to form a protective coating on the surface of the substrate, said sol containing more than 300 g of TiO nanoparticles₂ on dm³moreover, this sol can be obtained by preparation according to the above method in which the coating process is carried out. This method is optionally carried out in the presence of a binder.

The claimed invention also relates to the method of decomposing or inactivating impurities or denaturants that are in contact with a surface, comprising: applying a catalytic composition to a surface, said composition comprising a concentrated aqueous sol titanium nanodioxide containing more than 300 g of TiO nanoparticles₂ on dm³further, this sol can be obtained by preparation according to the above method; and allowing the surface to be irradiated with ultraviolet light / visible light when contaminants or contaminants contact this surface.

DESCRIPTION OF A PREFERRED EMBODIMENT OR EMBODIMENTS [0026] In the present description and in the claims set out below, reference will be made to a number of terms, which are to be understood as having the following meanings.

[0027] The term "titanium dioxide sol" means the colloidal suspension of TiO nanoparticles₂, wherein their size is less than 150 nm, preferably less than 100 nm. These TiO nanoparticles₂ they may be anatase, rutile or be amorphous or a mixture thereof.

The terms & quot; cross-flow filtration & quot; and & quot; cross-flow vibratory filtration & quot; mean filtration processes in which a tangential flow of the particulate suspension in the liquid medium is caused by the membrane surface and is simultaneously subjected to a pressure which acts in this medium. a method that tends to cause the flow of a liquid suspension medium through a membrane that is permeable to the liquid medium but not to the solid particles. The flow of this suspension through the surface of the membrane minimizes possible excessive accumulation of solid substances on the surface of the membrane. Mechanical vibration on the surface of the membrane can be used to reduce plugging or contamination of the membrane. Such a method is described, for example, in pat. U.S. Patent No. 4,952,317.

[0029] The present disclosure relates to a process for the preparation of concentrated aqueous sol titanium nanodioxide. In one embodiment of the present disclosure, a concentrated aqueous sol of titanium nanodioxide is prepared by a method comprising the following steps:

(a) contacting the acid sol of the titanium nanodioxide with a dispersing agent containing at least one of the water-soluble carboxylic acid, water-soluble carboxylic acid salt, water-soluble polycarboxylic acid, phosphate or silicate and with an alkalizing agent, wherein the pH of the sol titanium nanodioxide after contact it remains in the range of about 4.0 to about 10.0; and

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(B) subjecting the sol to a titanium nanodioxide with a pH-corrected membrane filtration, preferably cross-flow filtration or crossflow vibratory filtration, and further membrane filtration until the sol titanium nanodioxide contains more than 300 g of TiO nanoparticles₂ on dm³.

[0030] This is the method defined in claim 1.

[0031] In other embodiments of the present disclosure, the concentrated aqueous sol of titanium nanodioxide is prepared by a process comprising the following steps:

(a) providing an acid sol of titanium nanodioxide;

(b) contacting said acid sol of a titanium nanodioxide with a dispersing agent comprising at least one of a water-soluble carboxylic acid, a water-soluble carboxylic acid salt, a water-soluble polycarboxylic acid, a phosphate or a silicate, and an alkalizing agent, wherein the pH of the sol of the nanodioxide sol. the titanium on contact remains in the range of from about 4.0 to about 10.0; and (c) subjecting said sol to a titanium dioxide with a pH-corrected membrane filtration, preferably cross-flow filtration or crossflow vibratory filtration, and further membrane filtration until the sol titanium nanodioxide contains more than 300 g of TiO nanoparticles₂ on dm³.

[0032] In principle, all the steps of the method according to the present invention can be carried out at a temperature below 100 ° C, so that its implementation in industrial conditions is simple and economical. The concentrated aqueous sol of titanium nanodioxide produced by the process of the invention exhibits excellent stability over a wide pH range, in particular in the range of mild pH values ​​of 4.0 to 10.0 (e.g. 6.0 to 8.0), so that this sol is safe for the environment and easy to use. Furthermore, this concentrated aqueous sol titanium nanodioxide does not exhibit agglomeration and therefore does not require a milling step to achieve excellent translucency. In addition, although this sol of titanium nanodioxide is concentrated, it still has a low viscosity, making it particularly well suited for transport and direct use.

[0033] According to one embodiment of this method, an acid sol of titanium nanodioxide is disclosed. This acid sol of titanium nanodioxide can be obtained by any method, provided it contains an acidic colloidal suspension of TiO nanoparticles₂. These TiO nanoparticles₂ in the colloidal suspension, it can be prepared from anatase, rutile or amorphous TiO₂which have been obtained by any suitable method. Typical methods may include the hydrolysis of a suitable titanium compound, e.g. titanium tetrachloride, titanyl sulfate or organic or inorganic titanate, or oxidation of a oxidizable titanium compound, e.g. in the form of a vapor. [0034] In one embodiment, this acid sol titanium nanodioxide is prepared from TiO₂obtained in the precipitation step in the sulphate process. After precipitation, the hydrated titanium dioxide obtained is filtered, washed to remove impurities and contacted with an aqueous base solution to obtain a suspension having a pH close to neutral. The sulphate ions are then removed from the neutralized suspension by filtration and washing. In one aspect, the filter cake obtained by filtration is washed until the SO content₄^2- in the filtrate after washing it is less than 0.1 g / l (as can be seen as a result

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Titrations with barium chloride solution). Thereafter, an aqueous suspension of the washed filter cake is obtained to obtain an aqueous suspension of titanium dioxide hydrated with substantially no sulphate ion, which is then peptized with strong monoprotic acid to adjust the pH to about 2.0 or lower, preferably to about pH 1, 5 to get a sour sol of titanium nanodioxide.

[0035] This acid sol titanium nanodioxide is then contacted with the dispersing agent and with the alkalizing agent. This acid sol titanium nanodioxide can be contacted with the dispersing agent and alkalizing agent in any order or combination.

[0036] According to one embodiment, this acid sol titanium nanodioxide first contacts the dispersing agent. The dispersing agent comprises at least one of a water-soluble carboxylic acid, a water-soluble carboxylic acid salt, a water-soluble polycarboxylic acid, a phosphate or a silicate. In one embodiment, the water-soluble carboxylic acid is an α-hydroxycarboxylic acid. This α-hydroxycarboxylic acid may contain one, two or three carboxylic acid groups and includes, inter alia, lactic acid, glycolic acid, malic acid, tartaric acid, mandelic acid and citric acid. In another embodiment, the water-soluble carboxylic acid is a β-hydroxycarboxylic acid. In yet another embodiment, the water-soluble polycarboxylic acid is a dicarboxylic acid or a tricarboxylic acid. In other embodiments, the dispersant comprises one or more salts of the above acids. In still other embodiments, the dispersant comprises combinations of the above acids and salts and phosphates and silicates.

[0037] This acid sol of the titania and the dispersing agent may be contacted by any suitable method, e.g. conventional mixing in a container, for a period of at least about 0.1 hour, preferably at least about 0.25 hour and more preferably at least about 0, 5 hours. In another embodiment, the acid sol titanium nanodioxide and the dispersing agent may be contacted 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 acid sol titanium nanodioxide and the dispersing agent may be contacted for a period ranging from at least about 0.5 hour to less than about 3 hours.

[0038] The acid sol of the titanium nanodioxide is in addition contacted with the alkalizing agent. In one embodiment, this acid sol titanium nanodioxide is contacted with the alkalizing agent upon contact with the dispersing agent. Examples of alkalizing agents include alkanolamines, preferably water-soluble alkanolamine, e.g. isopropanolamine, and choline hydroxide. The period during which this acidic sol of the titanium nanodioxide is contacted with the alkalizing agent is a period of time sufficient to correct the pH of this acid sol titanium nanodioxide to a value in the range of from about 4.0 to about 10.0.

[0039] This pH correction titanium sol is then subjected to a membrane filtration, preferably a cross-flow filtration or a cross-flow vibratory filtration, whereby a concentrated sol titanium nanodioxide containing at least 300 g of TiO nanoparticles is obtained.₂ on dm³. In other embodiments, this sol of the titanium nanodioxide is subjected

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The result is a membrane filtration action that results in a concentrated sol titanium nanodioxide containing at least 500 grams of TiO nanoparticles.₂ on dm³preferably at least 550 g of TiO 2 nanoparticles per dm³ and more preferably at least 600 g of TiO 2 nanoparticles per dm³ and even more preferably at least 700 g of TiO 2 nanoparticles per dm³. Preferably, this concentrated sol titanium nanodioxide has a viscosity of about 0.001 Pa s to about 0.2 Pa at 20 ° C. The solids content of the pH-corrected titanium dioxide sol as a material subjected to membrane filtration is generally less than about 350 g of TiO2 nanoparticles per dm³. Accordingly, in one embodiment, the solids content, including the pH-corrected titania of the pH of the feed material, is from at least about 100 g TiO2 nanoparticles per dm.³ to less than about 350 g of TiO2 nanoparticles per dm³.

[0040] This pH correction titanium sol of soluble titanium may optionally be contacted with a washing agent, e.g. water, preferably demineralized water, at any time after the membrane filtration step to remove some or substantially all soluble salts from this sol titanium nanodioxide. In one embodiment, the pH corrected titanium nitenol sol is contacted with the washing agent in step (b) of the process described in claim 1. In another embodiment, the pH corrected titanium nitic oxide sol is contacted with the washing agent after concentrating this sol of the nanodioxide sol. titanium. Limiting the content of water-soluble salts in this sol of the titanium nanodioxide helps in the formation of a concentrated sol titanium dioxide that has a low specific conductivity, respectively.

[0041] In yet another aspect, this sol of the titanium nanodioxide may optionally be subjected to a coating process by contacting said sol of the titanium nanodioxide with the coating agent. This coating process may be carried out before, during or after any of the steps of the method referred to above. In one embodiment, this coating process is performed after contacting the acid sol of the titanium nanodioxide with the dispersing agent and with the alkalizing agent in step (a) of the process described in claim 1. In another embodiment, the coating process is performed during step (b) of the method described in claim 1, preferably after contacting the pH corrected titanium nitic acid dioxide with a washing agent to remove soluble salts from this sol titanium nanodioxide prior to concentration.₂. Typical inorganic oxides and hydrated oxides include one or more oxides and / or oxides of hydrated silicon, aluminum, titanium, zirconium, magnesium, zinc, cerium, phosphorus or tin. The amount of coating applied to the surface of TiO nanoparticles₂ may be in the range of about 0.1 wt%. up to 50% by weight an inorganic oxide and / or oxide hydrated with respect to the weight of TiO nanoparticles₂. Examples of basic coating agents include sodium silicate, potassium silicate, sodium aluminate or them

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EP 2 477 947 B1. Examples of acidic coating agents include aluminum chloride, aluminum sulfate or a mixture thereof.

[0042] During the coating process, a cation exchange resin can also be used to provide a low ionic strength of the sol of the titanium nanodioxide during this process and to maintain the colloid durability. In this embodiment, this sol of titanium nanodioxide is in contact with a basic coating agent, preferably sodium silicate, and with a cation exchange resin in a batch tank. The rate of addition of sodium silicate and the cation exchange resin is controlled so that the pH of the sol in the batch tank is in the range of from about 4.0 to about 10.0. In another embodiment, the sol and the alkaline coating agent are passed through a column or support containing a cation exchange resin at a rate such that the pH of the eluate remains in the range of from about 4.0 to about 10.0. Any suitable cation exchange resin is suitable for use, including generally known resins, for example, highly acidic cation exchange resins containing sulfonic acid groups, weakly acid cation exchange resins containing carboxylic acid groups or a mixture thereof. In some embodiments, if it is desired to remove the cation exchange resin, methods known in the art can be used to remove it.

[0043] An anion-exchange resin may also be used during the coating process. In this embodiment, this sol of the titanium nanodioxide is in contact with the acidic coating agent and the anion exchange resin in the batch tank. The rate of addition of this acidic coating agent and the anion exchange resin is controlled so that the pH of the sol in the batch tank is in the range of from about 4.0 to about 10.0. In another embodiment, the sol and acidic coating agent are passed through a column or medium containing the anion exchange resin at a rate such that the pH of the eluate remains in the range of from about 4.0 to about 10.0. Any suitable anion exchange resin, including generally known resins, is suitable for use.

[0044] The obtained concentrated aqueous sol titanium nanodioxide shows excellent durability and transparency. The currently known methods involve the drying of the sol titanium nanodioxide (which leads to some extent to the particle sticking), and then the milling step. The method of the present invention avoids both drying and grinding, but nevertheless provides the highly dispersed salts. Accordingly, nanodispersion in the systems of formulations containing concentrated sols of titanium nanodioxide prepared by the method of the invention can be obtained. In addition, the present invention provides a sol with a better physical form (i.e. a colloidal suspension against a cohesive low density powder), which greatly facilitates subsequent manipulation and processing of the sol titanium nanodioxide.

[0045] Concentrated aqueous sols of titanium nanodioxide prepared according to the invention are suitable for use in coating or in an article. For example, concentrated aqueous sols of titanium nanodioxide can be used: in personal care products and cosmetic preparations, such as products with sunscreen, moisturizing products, foundations for colored cosmetics, lipstick,

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EP 2 477 947 B1 lip balm, foot hygiene products and ointments; in coatings and masonry preparations, such as coatings used in the automotive industry, wood coatings, building coatings, roofing granulates, roof tiles, building siding, floor materials, swimming pool surfaces, and cement or concrete; as a catalyst or photocatalyst or as a support for catalytic products; in photovoltaic cells; in plastic elements, films and resin systems, including agricultural films, food packaging films, plastic molded parts for vehicles and polymer construction resins; in products containing rubber, including silicone rubber; in textile fibers used in fabrics and non-woven fabrics, including polyamide ones, polyaramide and polyimide textile products and in nonwoven products; in ceramic materials; in glass products, including architectural glass, vehicle glass and industrial glass; in flame retardants and in electronic components.

[0046] As stated above, the claimed invention also relates to a method of protecting a substrate surface from ultraviolet radiation comprising: applying a concentrated aqueous sol titanium nanodioxide to the surface of a substrate to form a protective coating on the surface of the substrate, said sol containing more than 300 g of TiO nanoparticles₂ on dm³moreover, this sol can be obtained by preparation according to the method described above in which the coating process is carried out. This method is optionally carried out in the presence of a binder. Accordingly, according to one embodiment, the concentrated aqueous sol titanium nanodioxide can be used in a method for protecting a substrate surface against ultraviolet radiation, said method comprising applying a concentrated aqueous sol titanium nanodioxide in the presence or absence of a binder to the surface of the substrate in the form of a coating. This sol can be applied by various application methods, for example dipping, spraying, spin coating, soaking, brushing and overlap.ania using a scraper. The concentrated aqueous sol of the titanium nanodioxide is preferably applied with a layer having a thickness of about 0.001 mm to about 0.2 mm measured in the liquid state. This applied layer then forms a protective coating on the surface of the substrate. This coating can optionally be dried. The substrates may include, among others, textile fibers, furniture, paper, paving stones, tiles, concrete, cement, wood, ceramics, polymer materials, leather, asphalt, building exterior and glass. In another embodiment, this concentrated aqueous sol titanium nanodioxide is incorporated into the cosmetic and this mixture is applied as above to the skin surface to provide protection against ultraviolet radiation.

[0047] As stated above, the claimed invention also relates to a catalytic composition comprising a concentrated aqueous sol titanium nanopreutide containing more than 300 g of TiO nanoparticles.₂₃ per dm, wherein the sol can be obtained by preparation according to the method described above. Accordingly, in one embodiment, a catalytic composition comprising a concentrated aqueous sol titanium nanodioxide prepared by the process of the present disclosure is disclosed. This catalytic composition containing a concentrated aqueous sol titanium nanodioxide can be used to carry out many different reactions and can be defined by the rate of conversion in a chemical reaction, the reactants being in contact with the composition in this reaction.

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Catalyst. In one embodiment, the catalytic composition is on a substrate. Examples of substrate materials include glass, ceramic, metal, plastic, cement, concrete, asphalt, textiles and paper. This substrate can be porous or nonporous. Examples of porous substrates include fiber mat, zeolite or porous film. The term "on the substrate" means a situation in which the catalytic composition is on at least a portion of the surface of the substrate. In the case of porous substrates, the term "on the substrate" also means a situation in which the catalytic composition is also in the pores of the substrate.

[0048] In one embodiment, the catalytic composition may be mixed with the substrate fluid and irradiated with visible light to effect a chemical reaction of one or more of the substrate fluid components. This catalytic composition can then be isolated from the fluid and reused in another volume of the substrate fluid. This catalytic composition can be used instead of conventional metal catalysts such as cobalt, nickel, copper, gold, iridium, lanthanum, nickel, osmium, platinum, palladium, rhodium, ruthenium, silver, strontium, yttrium, zirconium and tin.

[0049] In another embodiment, the catalytic composition is on a substrate and the substrate fluid can flow in contact with the substrate and the composition, while in the case of light exposure, a chemical reaction occurs to one or more substrate fluid components. In this configuration, this catalytic composition can be subjected to a continuous fluid stream and does not require separation of this catalytic composition from the liquid after the reaction has been carried out. For example, a catalytic composition may be applied to a substrate, e.g. a vehicle exhaust system, the exhaust system being provided with a visible light source or ultraviolet light, for example a light source being an optical fiber or a light source that is an LED diode.

[0050] As stated above, the claimed invention also relates to a method of decomposing or inactivating impurities or denaturants that are in contact with a surface comprising: applying a catalytic composition to a surface, said composition comprising a concentrated aqueous sol titanium nanodioxide containing more than 300 g of nanoparticles TiO₂ on dm³further, this sol can be obtained by preparation according to the method described above; and allowing the surface to be irradiated with ultraviolet light / visible light when contaminants or contaminants contact this surface. Accordingly, in another embodiment, the catalytic composition may be on a surface that is in contact with various impurities or contaminants in the environment, such as dirt, lubricants, and other contaminants and denaturants, both organic and inorganic. This catalytic composition, optionally a formulation containing this catalytic composition, is applied to the surface and the surface is irradiated with ultraviolet light / visible light when contaminants or contaminants contact this surface. As a result of exposure to ultraviolet / visible light, this surface becomes "self-cleaning" and decomposes or deactivates contaminants or contaminants. Glass, for example

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The self-cleaning may comprise a transparent or translucent coating of the catalytic composition applied on one or both sides of the glass. Then, when the glass is exposed to ultraviolet light / visible light, the contaminants in contact with the glass may be degraded. It may be desirable for the self-cleaning glass to have a hydrophilic surface that allows any remaining water-decomposing products to be washed out of the glass.

[0051] In another embodiment, the catalytic composition may be on a surface susceptible to microbes, such as bacteria and fungi and / or viruses. When such a surface is exposed to ultraviolet light / visible light, it can become a "disinfecting surface" because the microorganisms or viruses on the surface are destroyed or inactivated. For example, surfaces in residential, commercial or hospital buildings may include a coating of this catalytic composition applied to the surface. Microbes and / or viruses that come into contact with this surface may then be destroyed or inactivated when such a surface is exposed to ultraviolet light / visible light. Examples of surfaces,

[0052] This catalytic composition can also be applied to the surface to obtain temporary disinfection of this surface. For example, this catalytic composition can be incorporated into a cleaning composition. This cleaning composition may be in the form of liquid, foam or liquid. Applying this cleaning composition to a surface, and then exposing that surface to ultraviolet / visible light, can cause destruction or inactivation of microorganisms or viruses on that surface. Formulations of such cleaning compositions for use on the skin can be obtained to obtain a disinfectant personal care product.

[0053] This catalytic composition containing a concentrated sol titanium nanodioxide can also be used to purify air and / or water. For example, this catalytic composition can be mixed with contaminated air or water and irradiated with ultraviolet light / visible light. Contaminants present in air or water may decompose into volatiles or are more easily separated from air or water. For example, pollutants containing organic substances and halogenated substances can decompose into carbon dioxide and halogen ions, which can then be separated from air or water. In the case of air purification, the decomposition of pollutants such as NO and NO₂, individually or in combination, and VOCs, can allow you to get cleaner air and control odors in the air.

[0054] In another embodiment, the catalytic composition can be used to detect gases. Because the electrical conductivity of TiO nanoparticles₂ varies depending on the chemical composition of their environment, this variable conductivity of TiO nanoparticles₂ could be used to measure the type and / or content of one or more gases. Electrical resistance

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These nanoparticles of TiO₂ or material containing these TiO nanoparticles₂ can be measured in the environment and compared to electrical resistance in a control environment. The difference between the measured resistance and the resistance of the control can be related to the content and / or type of gas in the environment. Examples of gases that can be detected and / or designated include hydrogen, carbon monoxide, hydrogen sulfide and water. The gas sensor containing this catalytic composition is preferably used to detect gases under ambient conditions.

[0055] In a further embodiment, the catalytic composition can be used to produce hydrogen and oxygen from water. Water containing this catalytic composition can be degraded to hydrogen and oxygen by photocatalysis when water is irradiated with ultraviolet light / visible light. Such a distribution can also be carried out in a photoelectrochemical cell containing a quaternary oxide containing photoanode. It may be desirable to use a photoelectrochemical cell because it can allow the separate accumulation of hydrogen and oxygen from that cell.

[0056] In another embodiment, the catalytic composition can be used to generate electric current from sunlight, in particular in solar cells containing this catalytic composition and dye molecules that cause the sensitization of TiO nanoparticles.₂. For example, electricity is generated when dye molecules are excited by exposure to light. Such excited dye molecules transfer electrons to the conduction band of the nanoparticles that conduct electrons to the current collector connected to the electrical circuit with the receiver.

[0057] In yet another embodiment, the catalytic composition can be used in composite materials, including polymer composites, textiles, and nonwoven materials. For example, this catalytic composition can be incorporated into fibers in textile materials. These fabrics can provide a distribution of contaminants in contact with the fabric exposed to ultraviolet / visible light, resulting in self-cleaning or sanitizing fabrics.

[0058] In yet another embodiment, the catalytic composition can be used as a biologically active agent. In a water environment, for example in the interior of the body, TiO nanoparticles₂ exposed to ultraviolet / visible light can produce hydroxyl (OH) ions, superoxide ions (O₂^-) and / or hydrogen peroxide. Such a TiO nanoparticle₂exposure to ultraviolet light / visible light in the cell or in contact with the cell may therefore produce a toxic environment that damages or destroys this cell. In this way, this catalytic composition can be used as an anti-cancer agent after delivery to tumor cells. It may be desirable to combine this catalytic composition with a targeting agent that is selectively absorbed by the tumor cells. Light can be delivered to cells containing this laparoscopic catalytic composition, resulting in cell death or limitation of cell growth or multiplication. [0059] The present invention will be illustrated below by means of the following examples, which purpose is to exemplify this invention. Unless otherwise stated,

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EP 2 477 947 B1

Examples [0060] Example 1. Ilmenite was digested with concentrated sulfuric acid, whereby the cake was obtained after digestion. This digestion cake was dissolved in water, resulting in a crude lye containing iron sulfates, titanium sulfate and some suspended insoluble matter. Iron (III) iron was then subjected to chemical reduction and the caustic was filtered to remove insolubles. The liquor was then concentrated in vacuo and subjected to hydrolysis by heating to precipitate hydrated titanium dioxide, and seeds of crystallization were added. This hydrated titanium dioxide was separated from the impurities by washing and filtration, and then a suspension of hydrated titanium dioxide was obtained by mixing the hydrated filter cake with demineralized water.₄^2-and then resuspended in water. The pH of this suspension was adjusted to 1.50 by the addition of hydrochloric acid and stirred for 30 minutes to obtain an acid sol of titanium nanodioxide containing 33% solids. This acid sol titanium nanodioxide was then contacted with citric acid (1.0 citric acid per 10.0 g TiO2₂) by mixing in the tank for about 20 minutes. This sol was then contacted with mono-isopropanolamine by mixing in the tank for a period of time sufficient to adjust the pH of this sol to 8.00. This pH-corrected titanium dioxide sol was then subjected to cross-flow filtration, first contacting the sol with water to remove the soluble salts and to achieve a specific conductivity of 4.64 mS / cm, and then continue to filter with cross-flow until the sol contained 673 g of TiO nanoparticles₂ on dm³ based on the total weight of the aqueous sol. The sol obtained had a viscosity of 0.035 Pa s (measured at 19.3 ° C with a Brookfield viscometer with spindle No. 2 at 100 rpm). The modal value of the particle size was 43 nm, and the measurement was performed using a CPS disk centrifuge. The pH of this sol was 8.2.

[0061] Example 2. A stable sol titanium dioxide produced in Example 1 was introduced into a semi-matte acrylic emulsion at a volume concentration of a pigment in a dry coating of 18.23%. This coating was then applied to a polyester film with a thickness of 125 μιτι at a thickness of the wet coating layer of 150 μιτι. After curing, the obtained coating had an absorbance of 1.546 at a wavelength of 550 nm. Comparative coating containing commercially available anatase at the same concentration of TiO₂ had an absorbance of 2.489 at a wavelength of 550 nm. [0062] Prediction Example A. An acid sol titanium nanodioxide was prepared as in Example 1. This acid sol of titanium nanodioxide was then contacted with citric acid (1.0 citric acid per 10.0 g TiO2).₂) by mixing in the tank for about 30 minutes. This sol was then contacted with the monoisopropanolamine by stirring in the tank until the pH of this sol was about 8.0. TiO nanoparticles₂ suspended in a pH-corrected sol then heated to 75 ° C and coated with silica (20% by weight of SiO)₂ relative to TiO₂) by the simultaneous addition of sodium silicate and a cation exchange resin in such a way that the pH of the sol is maintained in the range of from about 5.0 to about 10.0. This sol titanium nanopreuton containing TiO nanoparticles₂ covered

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The silica was then subjected to cross-flow filtration by first contacting the sol with water to remove soluble salts, and then the cross-flow filtration was continued until the sol contained more than 30 wt.% Of the TiO nanoparticles.₂ coated with silica relative to the total weight of the sol.

[0063] Prediction example B. A composition with sunscreen containing the following components was obtained from the concentrated aqueous titanium dioxide sample prepared in the prediction example A:

<td>Component</td><td>wt%</td>

<td>Butylene glycol</td><td>3</td>

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

<td>Perfume</td><td>right amount</td>

<td>Silicic anhydride</td><td>3</td>

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

<td>Sol of the titanium nanodioxide (diluted with water to make obtain 12.5 g of TiO₂/ L)</td><td>80</td>

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EP 2 477 947 B1