Degradation of Diuron Photoinduced by Iron(III) in Aqueous Solution

Abstract

: The degradation of diuron photoinduced by iron(III) in aqueous solution has been investigated with di †erent iron(III) species (monomeric species Fe(OH)2`, dimeric species and water-soluble oligomeric species) Fe 2 (OH) 2 4ù nder monochromatic excitation at 365 nm and under sunlight. The rate of degradation depends on the concentration in Fe(OH)2`, the most reactive species in terms of radical formation. The major photoproduct is 3-(3,4-dichloro-OH phenyl)-1-formyl-1-methylurea which represents more than 60% of diuron disappearance. The mechanism only involves the attack by radicals arising fromOH iron(III) excited species. The half-lives of diuron when submitted to such a process in the environment were estimated to be 1È2 h and a few days according to the concentration of Fe(OH)2`(respectively 70% and \10% of total iron(III) concentration).

Hydrated ferric perchlorate, Fe(ClO4)3.XH2O in organic synthesis. A short review

“…The degradation process is initiated by the attack of OH radicals on 4-CA, leading to radical cations, 4-CA •+ as the major transient species. The formation of OH radicals, as found in several other studies [146][147][148][149][150][151].…”

Highly efficient photodegradation of the pesticide metolcarb induced by Fe complexes

“…It is of importance to note that the initial concentration of [Fe(OH)(H 2 O) 5 ] 2+ depends on the age of the solution, i.e. it decreased in the dark as a function of time leading to various iron(III) species as largely reported in the literature (Mazellier et al 1997). Since our initial solutions were freshly prepared, we can assume that (2.7 × 10 −4 mol L −1 ) at pH 3.4 led to an efficient decrease of metolcarb concentration.…”

Dégradation photochimique d'herbicides chlorophenoxyalcanoïques en milieux aqueux

“…Ces résultats sont conformes à d'autres travaux réalisés par différentes techniques, avec les mêmes molécules en milieux aqueux (OTURAN et al, 1999 ;BRILLAS et al, 2000) et d'autres molécules organiques comme le diuron (MAZELLIER et al, 1997), le bendiocarb (AARON et OTURAN, 2001), le pentachlorophénol (OTURAN et al 2001). Les meilleures performances photochimiques étant données par la technique photo-Fenton, nous avons choisi cette méthode pour l'étude de la dégradation de la molécule de 2,4,5-T.…”