Photooxidative Degradation of Pesticides in Water; Response Surface Modeling Approach

Abstract

Abstract The conventional water treatment technologies, mostly relying on physical and biological processes, seem to be inadequate for effective removal of priority substances such as pesticides, while advanced oxidation processes showed a good performance for the same purpose. The aim of the study was to evaluate UV-C/H2O2 and UV-C/S2O82– processes for treating seven pesticides listed as priority substances (PS-Ps) within the EU Water Framework directive; alachlor, atrazine, chlorfenvinphos, cybutryne, diuron, isoproturon and simazine. The influence of pH and pollutant/oxidant ratio ([PS-P]:[OX]) on the degradation kinetics was evaluated using full factorial plan and response surface modeling. The degradation of PS-Ps by both photooxidation processes obeyed first-order kinetics. Degradation kinetics of PS-Ps is highly depended on [PS-P]: [OX], while pH has minor significance, particularly in UV-C /S2O82– process. In most cases degradation kinetics by UV-C /S2O82– was several times faster in comparison to UV-C /H2O2 process. In addition, the inhibitory influence of NOM on the degradation of PSs in the mixture was determined.