Iron Oxides Photocatalyst Degradation Toxic Organic Pollutants

Water environmental contamination was an important problem, which was paid worldwide attention. Fenton and relations are potentially useful oxidation processes for destroying toxic organic pollutants in wastewater. The catalytic oxidation in H₂O₂/ oxidation system was a kind of derivative oxidation technique on base of Fenton. The present investigation utilized oxides iron, existing in the nature, as an alternative to iron ion originated from Fenton system, where the emphasis was placed on the photodegradation kinetics, the formation of active radicals and photodegraded products, thereby indicating photocatalytic reantion mechanism. In this thesis, a system of efficient dealing with toxic organic pollutants was established, utilizing visible light or sunlight and abundant iron oxides. Main study content was as follows:1. Iron oxides of different configuration of were synthesized according to refference by chemistry method. They were hematite, goethite, and akagatite. The methods and means were token as the characteristic of iron oxides by X ray diffration,spectra of ultraviolet reflecting,Infrared spectra and transmission electron mirror. The result indicated the structure of iron oxides was in good agreement with the literature according to different condition. What is more, they were excellent respond to visible light.γ-FeOOH was the most respond among iron oxides. The characteristic of the visible light (λ>420nm)-induced dye-sensitized photocatalytic photodegradation of organic pollutants including four kinds of dyes (Rhodamine B, Malachte green, Sulforhodamine B, Orange-II) and small toxic organic compound (dichlorophenol) was studied.2. The photocatalytic photodegradated characterisc of toxic organic pollutants, that goethite actives hydrogen peroxide was studed such as cation dyes(Rhodamine B, Malachte green), anion dyes (Sulforhodamine B, Orange-II) under visible light, and colorless toxic organic small molecule(2,4-Dichlorophenol) in ultraviolet irriadation. Comparing with photo- Fenton, visible light could accelerate the degradation of organic pollutants. The feasible pH could extend to the range from 3 to 11. During degradation the active species mainly related to hydroxyl radicals. According to choice of degradation condition, the method of photodegradating organic pollutants was established.3. The present invistigation was characteristic of catalytic degadation about 4-chlorophenol, 2-chlorophenol and 2, 4-Dichlorophenol in ultraviolet irriadation. The ratio of degradation was in the order: 2, 4-dichlotophenol>2-chlorophenol>4-chloro phenol.4. By means of modern experimental techniques ESR, the method of phtometry analysis detecting hydroxy radical,hydrogen peroxide in catalytic system was founded, which presumed that photocatalytic reaction involved hydroxy radical mechanism. In photocatalytic system by determining total carbon and the IR inspecting intermidiates of target compound, The result was shown that the end producetion was small molecule, such as amine, carboxylic acid compound in system of visible light degradation dye.