Photodegradation of the herbicide Norflurazon sensitised by Riboflavin. A kinetic and mechanistic study.
Chemosphere
; 57(6): 455-61, 2004 Nov.
Article
em En
| MEDLINE
| ID: mdl-15350407
The kinetics and mechanism of the Riboflavin (Rf)-promoted photochemical degradation with visible light of the herbicide Norflurazon (NF) has been studied by time-resolved and stationary techniques. Using light of wavelength higher than 400 nm--a region where NF is totally transparent--and with concentrations of Rf and NF of ca. 0.02 and 1 mM, respectively, only the excited triplet state of Rf ((3)Rf*) is quenched by NF, in competition with dissolved ground state triplet oxygen, O(2)((3)Sigma(g)(-)). NF degradation mainly occurs by reaction with superoxide radical anion O(2)(-) formed through two electron transfer steps: from NF to (3)Rf*, yielding Rf radical anion, and from this anion to O(2)((3)Sigma(g)(-)), regenerating ground state Rf. Although singlet molecular oxygen is also produced, NF only quenches this oxidative species in a physical mode. The global result is the photoprotection of the sensitiser and the photodegradation of NF.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Piridazinas
/
Riboflavina
/
Luz
Idioma:
En
Revista:
Chemosphere
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
Argentina
País de publicação:
Reino Unido