Photocatalytic degradation of pesticides in agricultural used waters

Various classes of organic contaminants can be easily destroyed and complet ely mineralized by titania-based photocatalysis. In the present work, we ha ve studied the influence of the basic photocatalytic parameters on the cata lyst activity as well as the identification of reaction intermediate produc ts and degradation pathways in model and real solution, encountered in agri cultural areas (rinsing waters). Various pesticides intensively used in agr iculture such as herbicides (2,4-D(dichloro-phenoxy-acetic acid)) or insect icides (tetrachlorvinphos, fenitrothion, pirimiphos-methyl, fenamiphos) wer e successfully degraded, either as pure active agents or as commercial form ulated reactants. A beneficial synergy effect has been obtained by adding a ctivated carbon to titania. An extension to 'helio-photocatalysis' has been performed using the pilot solar photoreactor of Plataforma Solar de Almeri a of the CIEMAT (Spain). (C) 2000 Academie des sciences / Editions scientif iques et medicales Elsevier SAS.