Photocatalytic Degradation of Selected s-Triazine Herbicides and Organophosphorus Insecticides over Aqueous TiO2 Suspensions
journal contributionposted on 2000-12-12, 00:00 authored by Ioannis K. Konstantinou, Theophanis M. Sakellarides, Vasilis A. Sakkas, Triantafyllos A. Albanis
The photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides was carried out in aqueous TiO2 suspensions under simulated solar light. The tested herbicides from the s-triazines group were atrazine, propazine, cyanazine, prometryne, and irgarol. The tested insecticides from the organophosphorus group were ethyl parathion, methyl parathion, ethyl bromophos, methyl bromophos, and diclofenthion. Degradation kinetics followed first-order reaction and has been monitored through gas chromatography. The degradation was fast with half-lives varying from 10.2 to 38.3 min depending on the nature and the structure of compounds. The generated transformation products (TPs) were formed via oxidation, dealkylation, and dechlorination for s-triazines and via oxidation and photohydrolysis for organophosphates. The TPs of irgarol, bromophos, and dichlofenthion were identified using solid-phase extraction (SDB-disks) and GC-MS techniques, and possible degradation routes were proposed showing similar degradation pathways as for other triazines and organophosporus pesticides. This work points out to the necessity of extended knowledge of the successive steps in a solar-assisted detoxification process.
Aqueous TiO 2 Suspensionsherbicidemethyl bromophosPhotocatalytic Degradationorganophosphorus groupdegradation pathwaysmethyl parathionoxidationDegradation kineticstransformation productsOrganophosphorus Insecticidesethyl bromophosethyl parathionorganophosporus pesticidesphotocatalytic degradationgas chromatographydegradation routesTiO 2 suspensionsTPirgarolwork points38.3 minorganophosphorus insecticides