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Ozone Reaction Kinetics for Water and Wastewater Systems - Chapter 7

Động học của phản ứng gián tiếp của Ozone trong nước Ở pH thấp hơn 12, các phản ứng gián tiếp của ozone phát triển động chế độ làm chậm hấp thụ ozone. Chúng được đặc trưng bởi sự hiện diện của ozone hòa tan và các yếu tố phản ứng và Hatta số thấp hơn hoặc gần với sự thống nhất và 0,3, tương ứng. Vì vậy, những phản ứng này là điển hình của ozonation nước uống, nồng độ các chất ô nhiễm là rất thấp (cao như là một phần triệu mức độ nhưng thường là ở phần. | 7 Kinetics of Indirect Reactions of Ozone in Water At pH lower than 12 the indirect reactions of ozone develop in the slow kinetic regime of ozone absorption. They are characterized by the presence of dissolved ozone and reaction factors and Hatta numbers lower than or close to unity and 0.3 respectively. Therefore these reactions are typical of drinking water ozonation where the concentrations of pollutants are very low as high as part per million level but usually in the part per billion level . Also some wastewater ozonation can develop in this kinetic regime as has been shown before specifically wastewater with low COD level 200 mg l . As presented in Section 7.1 in the slow kinetic regime the two ways of ozone action direct and indirect reactions the latter through free radicals can compete to remove any compound B present in the water. Indirect reactions are due to the ozone decomposition mechanism that can be initiated through the reaction of ozone with the hydroxyl ion which constituted the first and limiting step of the ozone mechanism leading to hydroxyl radicals see Section 2.5.1 . Also indirect reactions or those due to hydroxyl radicals can be favored through some other initiation reactions of ozone decomposition i.e. reactions of ozone with hydrogen peroxide direct ozone photolysis or some catalytic-induced reaction that constitute the so-called ozone-involved advanced oxidation processes AOPs as shown in the following chapters. In this section as a first approximation to the AOPs ozonation is considered as the ozone process carried out in the absence of initiators such as hydrogen peroxide or UV radiation or solid catalysts. Also note that at pH 12 the ozone decomposition reaction is slow so that if the direct reactions are fast the ozone decomposition will not take place. In the slow kinetic regime since ozone can react directly with the compounds present in water or through free radicals it is convenient to establish some guidelines in order to .