Động học của hệ thống Ozone / Hydrogen Peroxide Một quá trình oxy hóa tiên tiến (AOP) (xem thêm chương 2) được đặc trưng bởi việc sản xuất của các gốc hydroxyl, mà chủ yếu là chịu trách nhiệm cho quá trình oxy hóa. AOPs có thể được phân loại tùy thuộc vào các điều kiện thí nghiệm áp dụng. Như vậy, có AOPs thực hiện ở điều kiện nhiệt độ và áp suất môi trường xung quanh và tại điều kiện thử nghiệm nghiêm trọng. Thuộc về nhóm đầu tiên AOPs ozone liên quan đến chẳng hạn như ozone ở. | Q Kinetics of the Ozone Hydrogen Peroxide System An advanced oxidation process AOP see also Chapter 2 is characterized by the production of hydroxyl radicals that are mainly responsible for oxidation. AOPs could be classified depending on the experimental conditions applied. Thus there are AOPs carried out at ambient conditions of temperature and pressure and at severe experimental conditions. Belonging to the first group are the ozone-involving AOPs such as ozone at high pH ozone hydrogen peroxide O3 H2O2 ozone UV radiation O3 UV ozone catalyst O3 Cat etc. 1 2 and others such as the Fenton photofenton and photocatalytic processes 3-5 to name some of the most known processes. To the second group belong wet air and supercritical 7 What might be called a third group are those initiated at ambient conditions but that develop with the generation of high temperature and pressures such as the cavitation In this chapter we discuss ozone-hydrogen peroxide advanced oxidation kinetics. Staehelin and Hoigné9 extensively studied the reaction between ozone and hydrogen peroxide at different conditions of pH and concentration of H2O2 in both pure and natural water. In homogeneous systems they found a second-order kinetics for the ozone decomposition first order with respect to ozone and hydrogen peroxide with the particular characteristic that only the ionic form of hydrogen peroxide reacted with ozone. Thus only for experiments at pH 4 did they notice an appreciable rate of ozone decomposition that increased one order of magnitude with the increase of one unit in pH. The stoichiometric equation they proposed was k X 106 M-1S-1 O3 HO2 ---- O3 HO2 This reaction constitutes the initiation step of a radical chain mechanism that eventually leads to the formation of hydroxyl In fact this is also the accepted initial step of ozone decomposition in water due to the hydroxide ion as recently reported by Hoigné11 but previously proposed by .
