Oxidative Transformations of Contaminants in Natural and in Technical Systems

In this paper, we present case studies of oxidative transformations of contaminants by oxidants which are relevant in natural and in technical systems. These oxidants are reactive oxygen species (ROS), manganese(III,IV), iron(III), and molecular dioxygen (O2). Regarding ROS, we discuss i) their concentrations and their efficiencies as oxidants in natural waters and in water treatment, ii) reactions occurring in bromide-containing waters in the presence of ROS, iii) role of iron in the formation of ROS, and iv) quantitative structure-activity relationships (QSAR) of reactions of ROS with contaminants. Concerning MnIII and MnIV as oxidants, we present experimental studies on the oxidation of anilines by δ-MnO2. With respect to oxidative transformation of the hydrophilic organic contaminants ethylenediaminetetraacetate (EDTA) and nitrilotriacetate (NTA), we show that these organic complexing agents are efficiently oxidized by FeIII and O2, respectively, if catalyzed by light (for the oxidation of EDTA by FeIII and by enzymes (for the oxidation of NTA by O2).