title: Photo-Fenton degradation of the insecticide esfenvalerate in aqueous medium using a recirculation flow-through UV photoreactor.
abstract: The aim of the study was to evaluate the efficiencies of photo-Fenton (Fe(2+)) and (Fe(3+)) processes in the degradation of high-concentrations of esfenvalerate (in the form of aqueous emulsion of a commercial formulation) using a recirculation flow-through photoreactor irradiated with UV light from a 15 W lamp (254 nm emission peak). The results obtained using a basic photo-Fenton (Fe(2+)) reaction (esfenvalerate 17 mg L(-1); ferrous sulphate 1 mM; hydrogen peroxide 25 mM; pH 2.5) were compared with those acquired when ferrioxalate (1, 3 or 5 mM) served as the iron source. Degradation of the active component of the commercial formulation was significantly greater, and the rate of oxidation more rapid, using a photo-Fenton (Fe(3+)) process compared with its Fe(2+) counterpart. The most efficient degradation of the insecticide (75% in 180 min) was achieved with a reaction mixture containing 5mM ferrioxalate. However, under the same experimental conditions, degradation of pure esfenvalerate preceded much faster (99% in 60 min) and was 100% complete within 180 min reaction time.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil. colombo@iqsc.usp.br
authors.forename: Renata
authors.initials: R
authors.lastname: Colombo
authors.forename: Tanare C R
authors.initials: TC
authors.lastname: Ferreira
authors.forename: Suellen A
authors.initials: SA
authors.lastname: Alves
authors.forename: Marcos R V
authors.initials: MR
authors.lastname: Lanza
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000737:chemistry*; D009570:Nitriles / Q000737:chemistry*; D010777:Photochemistry; D011722:Pyrethrins / Q000737:chemistry*; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014867:Water; C017690:fenvalerate