(289aq) Mechanistic and Kinetic Studies of Heterogeneous Uv/Fenton Process for the Oxidation of Aqueous Organic Pollutants: Electron Transfer at Catalyst Surface to Initiate the Redox Process

Heterogeneous UV/Fenton process provides an attractive advanced oxidation process (AOP) option which employs porous iron oxalate and H2O2 as the photocatalyst and the oxidant, respectively. The upsides of such AOP lie in its low cost of material required and high treatment efficiency. To precisely describe a heterogeneous UV/Fenton process, from the mechanistic and kinetic point of view, this study investigates heterogeneous UV/Fenton process in oxidizing aqueous pollutants that can hardly be degraded biologically. The roles of photocatalyst, H2O2 and light have been distinctly identified by this work. Iron oxide serves as the electron provider which, with the assistance of light irradiation, elevates its electrons to conduction band. The thus created ?electron-hole' pairs promote the redox reaction between H2O2 and H2O at the catalyst surface, resulting in the generation of hydroxyl radicals and commencement of pollutant degradation. On basis of these explanations on reaction mechanism, a simplified kinetic model was developed in line with ?free radical reaction' concept. The model simulation concludes that when H2O2 is in great excessive amount, H2O2 consumes in parallel with pollutant degradation, both of which follow first-order reaction. The established kinetic model tallies well with experimental observations. The impact of H2O2 on pollutant degradation is also discussed in light of the close relationship between pollutant degradation and H2O2 consumption.