Applicability of solar photo-Fenton process to the remediation of water polluted with pesticides

Abstract

The applicability of solar photo-Fenton process to the degradation of three pesticides in pure and natural waters was investigated in Fe(III)/H2O2/UV–Vis and Fe(III)/H2O2 UV–Vis oxidation systems at pH 2.8 and 7.2. The pesticides concentrations were determined by HPLC analysis. Furthermore, total mineralization of the pesticides in these systems was evaluated by monitoring the decreases in DOC concentrations with solar simulator irradiation time by TOC analysis. The results obtained indicate that the spontaneous degradation due to solar illumination by Fe3+/H2O2/UV–Vis system is more effective than Fe2+/ H2O2/UV–Vis system in Milli-Q water and river water at pH 2.8. This great enhancement in the pesticides degradation rate in the photo-Fenton reaction system Fe3+/H2O2/UV– Vis compared to Fe2+/H2O2/UV–Vis systems at pH 2.8 is due to the higher rate of ·OH generation in this system in Milli-Q water and river water (4.01 and 5.26 uM/min) compared to Fe2+/H2O2/UV–Vis systems 2.44 and 2.90 uM/min. respectively. At both pH values, the order of pesticides degradation was diuron > fenitrothion > fenarimol which seems to be related with their solubility. Results obtained from this study makes it plausible to apply the photo-Fenton process to the remediation of water polluted with toxic pesticides