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titanium dioxide photocatalytic degradation of organic matter

2014-02-22 by seoer8

Hashimoto [155] , who choose the titanium dioxide more difficult oxidation of n-hexadecane as an object , TiO2 as catalyst under UV irradiation , photocatalytic oxidation of low-carbon hydrocarbons do a more detailed study . The results of long-chain alkanes can be completely decomposed into H2 and CO2. C16H34 + 32H2O → 16CO2 + 49H2 8-38 released during the course of the reaction the ratio of H2 and CO2 is always about 3. They think aliphatic hydrocarbon photocatalytic oxidation gradually oxidized to the corresponding alcohols , aldehydes, hydroxy acid intermediate , and then through the Kolbe reaction of hydroxy acid is decomposed into lower hydrocarbons and H2 and CO2. Aromatics can also be TiO2 photocatalytic oxidation to CO2, but there will be a small amount of intermediate generation, such as catechol, hydroquinone , and muconic acid and other phenols . Okamoto , etc. By tracking analysis during the reaction of phenol original , intermediates and products observed reaction into three stages: the first stage mainly benzene hydroxy compound , which is detected between hydroquinone , o hydroquinone, pyrogallol 2 - hydroxy-1 ,4 - benzoquinone , 1,4 - benzoquinone. The second phase of polar hydroxy acids and aldehydes , mainly in about ten minutes after the complete removal of phenol , aromatic hydroxy compounds are also disappearing . The third stage is gradually increased CO2 production , three hours after the reaction , 80% conversion of phenol to CO2. Phenol can be inferred photocatalytic degradation reactions , mainly through hydroxylation process completed . First with phenol hydroxyl radical reaction of the dihydroxy cyclohexadiene radicals further oxidized quinone dehydration and finally degraded to CO2.
( 2 ) halogenated organic compounds are widely distributed range of halogenated organic compounds in water , a class of toxic pollutants. Such materials include the halogenated aliphatic hydrocarbons , halogenated aromatic hydrocarbons, halogenated fatty acids , used as pesticides, insecticides and the like. Priority hazardous substances controlled by countries such substances in the " blacklist" occupies a large proportion. Therefore, the study of halogenated organics management is an important issue of water pollution treatment . Photocatalytic technology in the treatment of organic halide display a good prospect that the current research in this regard have been many reports . ① halogenated aliphatic hydrocarbons and halogenated carboxylic acids in the city water in the purification process using the commonly used method of chlorination , thereby resulting in water containing a small amount of chlorinated hydrocarbons and chlorinated carboxylic acid , such as chloroform , dichloroacetic acid and the like.
Son Sile titanium dioxide because of its high photocatalytic characteristics are widely used in photocatalytic wastewater treatment , photocatalytic coatings , photocatalytic air purification, thin film solar cells and other environmental pollution control and energy industries.

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