Photocatalytic degradation of pesticides in agricultural used waters

Various classes of organic contaminants can be easily destroyed and completely mineralized by titania-based photocatalysis. In the present work, we have studied the influence of the basic photocatalytic parameters on the catalyst activity as well as the identification of reaction intermediate products and degradation pathways in model and real solution, encountered in agricultural areas (rinsing waters). Various pesticides intensively used in agriculture such as herbicides (2,4-D(dichloro-phenoxy-acetic acid)) or insecticides (tetrachlorvinphos, fenitrothion, pirimiphos-methyl, fenamiphos) were successfully degraded, either as pure active agents or as commercial formulated reactants. A beneficial synergy effect has been obtained by adding activated carbon to titania. An extension to 'helio-photocatalysis' has been performed using the pilot solar photoreactor of Plataforma Solar de Almeria of the CIEMAT (Spain). (C) 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.