Enhancement of pesticide photo-Fenton oxidation at high salinities

The performance of the photo-Fenton reaction under high salinity conditions (up to 50 mS cm(-1)) has been tested regarding the oxidation of two pesticides, imidacloprid and methomyl, in the shape of their commercial formulations. In opposition to what is commonly outlined in the literature, an enhancement in pesticides depletion has been found due to the positive participation of halogen radicals, Cl. However, this beneficial effect does not improve organic carbon elimination but rather displays worse total organic carbon (TOC) depletion. This effect is most likely due to the hydroxyl radicals scavenging and the complexation of Fe3+ by chloride salts, which reduce the availability of reagents. Although salts/Fe3+ interaction was observed, Fe3+ interaction with the organic content was revealed as more relevant, especially for imidacloprid. (C) 2012 Elsevier B.V. All rights reserved.