tailieunhanh - Ozone Reaction Kinetics for Water and Wastewater Systems - Chapter 9

Động học của hệ thống bức xạ tia cực tím Ozone Photolysis của ozone dung dịch nước đã được chủ đề của nhiều công trình nhằm thiết lập cơ chế của phản ứng và động học của quá trình photolytic. Peyton và Glaze1 báo cáo rằng photolysis ozone hòa tan trực tiếp sản lượng hydrogen peroxide, thì photolysis của hydrogen peroxide được hình thành và / hoặc phản ứng của nó với ozone bắt đầu cơ chế của phản ứng gốc tự do dẫn đến gốc tự do hydroxyl: O3 + H2O hν → H2O2 H2O2 hν →. | 9 Kinetics of the J Ozone-UV Radiation System The photolysis of the aqueous ozone has been the subject of many works aimed to establish the mechanism of reactions and the kinetics of the photolytic process. Peyton and Glaze1 reported that the photolysis of dissolved ozone directly yields hydrogen peroxide then the photolysis of the hydrogen peroxide formed and or its reaction with ozone starts the mechanism of free radical reactions leading to the hydroxyl radical O3 H2O h H2O2 H2O2 H 2HO and Reaction etc. see Table or Table . According to these observations the O3 UV system is the most complete ozone involving an advanced oxidation process since there could be up to three possible initiation reactions for the generation of hydroxyl radicals. These reactions are those possibly due to the initiating species present in the water see Reaction and Reaction the free radicals formed from the photolysis of hydrogen peroxide Reaction and the free radicals formed from the ozone-hydrogen peroxide Reaction . In addition in the UV O3 system there are also three other possible ways of direct oxidation photolysis direct ozonation direct oxidation with hydrogen peroxide although kinetically unfavorable in most of cases and direct photolysis. Since direct photolysis can constitute a significant kind of oxidation this kind of treatment is first examined from the kinetics point of view. The radiation applied can be visible or ultraviolet although for kinetic studies involving ozone processes the commonly used radiation is the 254 nm wavelength because ozone presents at this wavelength its maximum absorption efficiency. KINETICS OF THE UV RADIATION FOR THE REMOVAL OF CONTAMINANTS FROM WATER Many substances that absorb radiation can decompose through what is known as photolytic reactions or simply direct photolysis. The photolytic process can also be 2004 CRC Press LLC due to direct and indirect mechanisms. In the direct mechanism the target .