Degradation of carbofuran by using ozone, UV radiation and advanced oxidation processes

The degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate), a frequently used carbamate derivative pesticide that is considered a priority pollutant, is carried out in batch reactors by means of single oxidants: ozone, UV radiation and Fenton's reagent; and by the advanced oxidation processes (AOPs) constituted by combinations of ozone plus UV radiation, UV radiation plus H2O2, and UV radiation plus Fenton's reagent (photo-Fenton system). For all these reactions, the apparent pseudo-first-order rate constants are evaluated in order to compare the efficiency of each process. In addition and by means of a competition kinetic model, the rate constants for the reaction of carbofuran with ozone and with hydroxyl radicals are also determined. The improvement in the decomposition levels of carbofuran reached by the combined processes in relation to the single oxidants, due to the generation of the very reactive hydroxyl radicals, is also established in every process. For the oxidant concentrations applied, the most effective process in removing carbofuran was the photo-Fenton system. (C) 2002 Elsevier Science B.V. All rights reserved.