In this work, chemical oxidation of
mesotrione herbicide by Fenton process in acidic medium (pH 3.5) was investigated. Total disappearance of
mesotrione and up to 95% removal of total organic
carbon (TOC) were achieved by
Fenton's reagent under optimized initial concentrations of
hydrogen peroxide (H(2)O(2)) and ferrous
iron (Fe(2+)) at pH 3.5. The time-dependent degradation profiles of
mesotrione were satisfactorily fitted by first-order kinetics. Competition kinetic model was used to evaluate a rate constant of 8.8(± 0.2) × 10(9)M(-1) s(-1) for the reaction of
mesotrione with
hydroxyl radicals. Aromatic and aliphatic intermediates of
mesotrione oxidation were identified and quantified by high performance liquid chromatography (HPLC). It seems that the degradation of
mesotrione by Fenton process begins with the
rupture of
mesotrione molecule into two moieties: cyclohexane-1,3-dione derivative and 2-nitro-4-methylsulfonylbenzoic
acid. Hydroxylation and release of sulfonyl and/or nitro groups from 2-nitro-4-methylsulfonylbenzoic
acid lead to the formation of polyhydroxylated
benzoic acid derivatives which undergo an oxidative opening of
benzene ring into
carboxylic acids that end to be transformed into
carbon dioxide.