Kinetics and mechanism of the degradation of the pesticide metsulfuron methyl induced by excitation of iron(III) aqua complexes in aqueous solutions: steady state and transient absorption spectroscopy studies.
The degradation of the pesticide metsulfuron methyl induced by excitation of iron(III) aqua complexes was studied at 365 nm. The process involved the formation of hydroxyl radicals and was shown to depend on Fe(OH)(2+) concentration. The second order rate constant of the reaction of metsulfuron methyl and hydroxyl radical was evaluated by laser flash photolysis experiments to k = 3.5 x 10(9) mol(-1) L s(-1). Various products were formed. Among them 2-amino-4-methoxy-6-methyl-1,3,5-triazine, 2-(carbomethoxy) benzenesulfonamide and hydroxylated derivatives represent the major photoproducts. Compounds arising from the cleavage of the triazine moiety were also found. After prolonged irradiation, a total disappearance of metsulfuron methyl and a complete mineralization of the solution were obtained.
Laboratoire de Photochimie Moleculaire et Macromoleculaire, Universite Blaise Pascal, UMR CNRS 6505, F-63177 Aubiere Cedex, France.
Salah
S
Rafqah
Ahmed
A
Aamili
Sylvie
S
Nelieu
Lucien
L
Kerhoas
Jacques
J
Einhorn
Gilles
G
Mailhot
Mohamed
M
Sarakha