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Photocatalytic Degradation of Selected s-Triazine Herbicides and Organophosphorus Insecticides over Aqueous TiO2 Suspensions
journal contribution
posted on 2000-12-12, 00:00 authored by Ioannis K. Konstantinou, Theophanis M. Sakellarides, Vasilis A. Sakkas, Triantafyllos A. AlbanisThe 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.
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Keywords
Aqueous TiO 2 Suspensionsherbicidemethyl bromophosPhotocatalytic Degradationorganophosphorus groupdegradation pathwaysmethyl parathionoxidationDegradation kineticstransformation productsOrganophosphorus Insecticidesethyl bromophosethyl parathionorganophosporus pesticidesphotocatalytic degradationgas chromatographydegradation routesTiO 2 suspensionsTPirgarolwork points38.3 minorganophosphorus insecticides