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Photocatalytic auto-cleaning process of stainsRelated Patent Categories: Cleaning And Liquid Contact With Solids, Liquid Treating Forms And Mandrels, Including Application Of Electrical Radiant Or Wave Energy To WorkPhotocatalytic auto-cleaning process of stains description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060137708, Photocatalytic auto-cleaning process of stains. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to photocatalytic oxidation of spices with titanium dioxide coated on ceramic tiles and in particular relates to reliable and successful use of TiO.sub.2 coated ceramic tiles and in-house fluorescent light to degrade persistent stains caused by splashing, spilling of chilies and turmeric on the walls/platform of kitchens. BACKGROUND OF THE INVENTION [0002] Fluid streams such as water or effluents often include contaminants such as dissolved halogenated or organic compounds, nitrogen oxides, halocarbons, pesticides, organic dyes, etc. Photocatalysts can be used to purify fluid streams by converting these contaminants into less harmful materials or substances, which may be more easily removed therefrom. [0003] The conversion of contaminants occurs when the effluent or toxic pollutant is brought in contact with the photocatalyst illuminated by a nearly ultra-violet or fluorescent light source. The photocatalyst is either in the coated form or in dispersed form. Typically, photocatalyst is deposited on the surface of a support structure to provide a stable photo catalytic surface and to ensure that the flowing stream does not carry it away. To be effective, the contaminants must be brought into contact with the photocatalyst. [0004] The photocatalytic oxidation reaction with TiO.sub.2 either in coated or dispersed form has been known for some time. A synthetic and commercially available TiO.sub.2 containing greater than 75 percent of anatase can be used as a photocatalyst to degrade various organic species to render it environmentally safe. These TiO.sub.2 either coated on support material or dispersed in aqueous solution have been found to have good photocatalytic degradation efficiencies when it is desired to impact oxidation or reduction properties to organic moieties. Titanium dioxide have specific properties for its use as a photocatalyst such as (i) oxidation of water-bound environmental contaminants, irradiated with solar or simulated light; (ii) complete photo degradation of halocarbons, viz. dibromo-ethane, trichloroethylene; chloro-benzenes etc widely used as solvents in pesticides, insecticides, herbicides; (iii) photo destruction of different classes of organic dyes and biological stains from waste water; (iv) oxidation of cyanide found in rinse water of steel industry, electroplating, gold extraction, extraction in mines, to less toxic oxidation products like OCN. The latter is further oxidized to NO.sup.3- and CO.sub.3.sup.2-; (v) reduction of metal ions to metallic state to remove toxic and noble metal ions from waste water; (vi) photo destruction of anionic, cationic and non-ionic surfactants under solar or simulated light using aqueous TiO.sub.2 suspensions. [0005] The wide spectrum of surface properties such as crystallinity, high percentage of anatase, surface charge state, surface hydration/hydroxylation, combined with fine particle size and high surface area, low density and chemical inertness make titanium dioxide a potential industrial photocatalyst in the field of photo/environmental chemistry. Such a TiO.sub.2 in its porous state can be employed for the photo catalytic oxidation reaction employing simple method described hereinto. [0006] The inorganic molecules and ions, viz. CO.sub.2, SO.sub.2, NO.sub.3, NH.sub.4.sup.+ are the reaction products of photocatalytic oxidation reaction on TiO.sub.2 surfaces. Under favourable conditions, the organic species present in (i) waste water effluents (ii) halo carbons (iii) dyes and dye stuff (iv) surfactants (v) toxic pollutants etc. undergoes photocatalytic oxidation reaction, when the TiO.sub.2 surface is irradiated with ultra violet or fluorescent tube-light. [0007] U.S. Pat. No. 5,035,784 (1991) to M. A. Anderson et al. has disclosed the preparation of a highly porous titanium ceramic membrane and which have the propensity to absorb organic molecules, and also to degrade the complex organic molecules under UV light. The preparation involves hydrolysis of titanium alkoxide at room temperature in organic alcohol. The addition of large amount of water will precipitate titanium hydroxide, which is then peptized with HNO.sub.3 at room temperature. The suspension is heated with stirring at 85.degree. C. and maintained it for 12 hours, whereby the colloid gel is solidified onto a support which on firing at 500.degree. C. results in a highly porous, continuous web of sintered particles forming a rigid membrane. The drawback associated with this processes are (i) tight control of pH of the colloidal mixture; ii) any alcohol as solvent will not be adequate. The alcohol solvent is preferably an alkyl alcohol different from alkyl radical in titanium alkoxide and (iii) the firing temperature is critical as it may cause as it may cause cracking into the resulting ceramic. [0008] U.S. Pat. No. 5,874,701 (1999) to T. Watanabe et al. discloses a process for photo catalytically treating hospital room or living space contaminated by bacteria or an interior space bearing airborne malodorous substances. It comprises of a thin film of TiO.sub.2 coated on the inner walls of the room, which is irradiated by a fluorescent lamp and photo excited by small amount of UV radiation included in the light of the lamp. The wattage of fluorescent lamp, distance between the thin film and lamp, intensity of UV light were studied to photo decompose the bacteria and chemical compounds deposited on the photo excited thin film. This process has the limitation that it can photo decompose bacteria and hazardous chemical compounds (airborne) substances. It does not claim anything about auto cleaning of stains caused by spices on kitchen walls and platforms. [0009] U.S. Pat. No. 5,779,912 (1998) to A Gonzalez Martin et al. discloses a method and apparatus for mineralizing organic contaminants in water or air by photocatalytic oxidation in a unique two-phase or three-phase boundary system in a photocatalytic reactor, which works effectively at ambient temperature and low pressure. The semi-conductor TiO.sub.2 is coated by different technique on porous substances viz. porous polymers; porous metal; porous carbon or graphite; or porous ceramic in order to have passage there through for different oxidant, used in different proportion in the decomposition process. The drawback associated with this process is that the system is effective when binary metal oxides are selected as photocatalyst, and at low pressure. The presence of oxidant is quintessential for photodecomposition. [0010] Japanese Patent No. 9,276,694 (1997) to O. Taware discloses a method which involves the preparation of a paste from TiO.sub.2, glass powder and water and applying a thin film of this paste on ceramic surface prior to calcinations, in order to obtain a stiff and less porous TiO.sub.2 layer that has strong adherence to substrate and long service life. The drawback associated with method is that this photocatalyst is compatible for decomposition of nitrogen and phosphorous compounds, for cleaning air, exhaust gas and water. OBJECTS OF THE INVENTION [0011] The main object of the invention is to provide a method for photocatalytic oxidation of spices with TiO.sub.2 coated on ceramic tiles, which obviates the drawbacks and limitations as detailed above. [0012] Another object of the invention is auto-cleaning of stains caused by spurting of spices on kitchen walls and platforms, where it is not easily reachable manually. [0013] Another object of the invention is to provide stable deposition of photocatalyst on surface of substrate and to ensure that photocatalyst is not removed by flowstream of effluent. [0014] Another object of the invention is to make the degradation of spices more effective even in the presence of fluorescent light. [0015] Another object of the invention is to use anatase type of TiO.sub.2 and the like TiO.sub.2 as Photocatalysts. [0016] Another object of the invention is to provide a simple and efficient method of coating a support material, while avoiding complexities involved of known coating techniques. SUMMARY OF THE INVENTION [0017] Accordingly the present invention provides a process for degradation of stains caused by spices with TiO.sub.2 coated on ceramic tiles, which comprises of (i) spraying of 2 to 5% of TiO.sub.2 powder dispersed in 5 percent silica sol on rough surface of ceramic title; (ii) drying and heating the tiles in the temperature range of 100 to 350.degree. C. for 20 to 60 minutes; (iii) again spraying and drying/heating the titles as in step (ii); (iv) placing droplets of slurry containing dispersed chilly or turmeric in water or an emulsion with oil containing dispersed chilly or turmeric in the concentration range of 1 to 5 percent, on the coated ceramic title; (v) exciting the TiO.sub.2 surface with ordinary fluorescent light having an intensity in the range of 5 to 20 lux, for effective contact time in the range of 20 to 80 minutes. [0018] In an embodiment of the invention, the photocatalyst such as TiO.sub.2 is in powder form and contains at least 80% by weight of anatase type TiO.sub.2; surface area in the range of 25 to 60 m2g-1 and X-ray diffraction peaks at 20=25.35 A .degree.; 37.88 A .degree. and 48.15 A .degree.. [0019] In another embodiment of the invention, the support material is a ceramic tile, plane glass or a hard acrylic sheet. [0020] In yet another embodiment of the invention, TiO.sub.2 powder in the range of 2 to 5% is dispersed in 5 to 10% silica sol and then sprayed on support material. Continue reading about Photocatalytic auto-cleaning process of stains... Full patent description for Photocatalytic auto-cleaning process of stains Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Photocatalytic auto-cleaning process of stains patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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