Photo-Fenton degradation of the herbicide 2,4-D in aqueous medium at pH conditions close to neutrality

SCHENONE, A.V.; ALFANO, O.M.; CONTE, L.O.

JOURNAL OF ENVIRONMENTAL MANAGEMENT

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2016 vol. 170 p. 60 - 69

0301-4797

A theoretical andexperimental study of the photo-Fenton degradation of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in water is presented. A kinetic modelderived from a reaction sequence is proposed using the ferrioxalate complex asiron source for conditions of pH = 5. The kinetic model was employed to predictthe concentrations of 2,4-D, 2,4-dichlorophenol (2,4-DCP), hydrogen peroxide (HP) and oxalate (Ox) in a flat plate laboratory reactor irradiated with asolar simulator. Two types of incident irradiation levels were tested bydifferent combinations of attenuation filters. The effects of the oxalate/Fe+3molar ratio (Ox/Fe), the reaction temperature (T) and the 2,4-D/HP molar ratio(R) on the photo-Fenton process were also investigated. For low radiation leveland operating conditions of R = 50 and T = 50 °C, a 2,4-D conversion of 95.6% was obtained after 180 min. Moreover, the 2,4-D conversion was almost100% in only 120 min when the system was operated under the same operatingconditions and high radiation level. From the proposed model and the experimentaldata, the corresponding kinetic parameters were estimated applying a nonlinearregression method. A good agreement between the kinetic model and experimentaldata, for a wide range of simulated solar operating conditions, was observed.For 2,4-D, 2,4-DCP, HP and Ox concentrations, the calculated RMSE were 1.21 ×10−2, 5.45 × 10−3, 2.86 × 10−1 and 2.65 × 10−2 mM, respectively.