TiO2 — photocatalytic degradation of organic contaminants in water included studies of water samples taken from a heavily polluted well under exposure to natural sunlight; waters from liquid commercial pesticide formulations, simulating treatment of rinse waters of agricultural sprayers; in these studies most compounds were appreciabely degraded within 3.5 h but more complete detoxification required longer exposure. Photocatalytic oxidation of dye chemicals from textile industry resulted in complete degradation of selected azo and thiazine dyes. In the case of dyes the photocatalytic oxidation is accompanied by a reaction of dye sensitization. Enhanced degradation of colourless refractory pollutants has been observed in the combined process. The main advantage of the combined approach is the utilization of visible light for the degradation of refractory organic pollutants, both coloured and colourless, which cannot be photosensitized in the visible region.Different reaction patterns of photooxidation has been witnessed for the herbicides metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4 -triazine-5-one) and bromacil (5-bromo-3-sec-butyl-6-methyluracil). In metribuzin oxygen has a pronounced effect on the rate of photooxidation, while the influence of hydrogen peroxide is quite moderate. The photolytic process in this case would apparently start via a reaction of the excited herbicide molecule with hydrogen peroxide or with oxygen. In the case of bromacil, oxygen does not have a pronounced effect on the rate of photooxidation, which however is considerably enhanced by hydrogen peroxide. The reaction is initiated by hydroxyl radicals generated by hydrogen peroxide photolysis. These conclusions are supported by the different effects of isopropanol inhibition.
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- Field Studies in Solar Photocatalysis for Detoxification of Organic Chemicals in Water and Effluents
- Springer Berlin Heidelberg
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