Modeling the photodegradation of emerging contaminants in waters by UV radiation and UV/H₂O₂ system

Abstract

Five emerging contaminants (1-H-Benzotriazole, N,N-diethyl-m-toluamide or DEET, Chlorophene, 3-Methylindole, and Nortriptyline HCl), frequently found in surface waters and wastewaters, were selected to be photooxidized in several water matrices. Previous degradation experiments of these compounds individually dissolved in ultra pure water were performed by using UV radiation at 254 nm and the Fenton's reagent. These oxidation systems allowed the determination of the quantum yields and the rate constants for the radical reaction between each compound and hydroxyl radicals. Later, the simultaneous photodegradation of mixtures of the selected ECs in several types of water (ultrapure water, reservoir water, and two effluents from WWTPs) was carried out and a kinetic study was conducted. A model is proposed for the ECs elimination, and the theoretically calculated concentrations with this model agreed well with the experimental results obtained, which confirmed that it constitutes an excellent tool to predict the elimination of these compounds in waters.

Keywords:

• Emerging contaminants (ECs)
• UV radiation
• quantum yields and radical rate constants
• natural waters
• prediction of elimination

Acknowledgments

The authors gratefully acknowledge financial support from the Ministerio de Educación y Ciencia de España and FEDER through Project CTQ 2010–14823, and from Gobierno de Extremadura through Project RNM021. E. Rodriguez thanks to the Gobierno de Extremadura for her FPI Ph.D. Grant.