Photo-Fenton degradation of 2,4-D in a pilot-plant solar reactor.

FARIAS JORGELINA; ALBIZZATI ENRIQUE D; ALFANO ORLANDO M

Santa Fe, Argentina

Workshop; 2nd Latin American Pesticide Residue Workshop, Food and Environment; 2009

Universidad Nacional del Litoral (UNL), Facultad de Ingeniería Química (FIQ), Laboratorio Central (LC),

The feasibility of applying solar radiation has made the photo-Fenton system an economical and competitive process. It has been demonstrated that the Fenton degradation of pollutants can be considerably improved by UV/Visible radiation and temperature increase [1]. In the present work, the use of solar radiation to destroy the 2,4-dichclorophenoxyacetic acid (2,4-D) with a photo-Fenton treatment is presented. This study is performed in a novel solar reactor that uses the UV-Visible and Near-Infrared solar radiation to promote the pollutant degradation. Initially, a kinetic model of the Fenton and photo-Fenton degradation rates for relatively low concentrations is proposed, using a procedure similar to that employed in a previous work [2]. A good representation of experimental data for different temperatures, hydrogen peroxide to 2,4-D initial concentration ratios, and ferric initial concentrations is obtained. The kinetics model was used in a predictive way for describing the 2,4-D and DCP (main intermediate product) concentrations as a function of time in the pilot-plant solar reactor. To do this, we have solved the thermal energy and mass balances and the radiative transfer equation (RTE) together with spectral UV – total broadband solar radiation. Fluctuations of solar irradiance with time were considered in the proposed reactor model. The spectral and broadband solar radiation incident on the reactor window were calculated from a computational code: the SMARTS2 program; in addition, the direct (or beam) and diffuse UV/Visible radiation components have been taken into account in the evaluation of the radiation field inside the reactor. Predicted 2,4-D solar conversions compared with experimental values show a root mean square errors of 0.015 mM. The solar photo-Fenton treatment was an efficient process to destroy the 2,4-D. No aromatic compounds were detected after 60 min of time. After 30 min, the combined effect of UV/Visible and thermal sunlight produces a 2,4-D conversion of 144.2% greater than that obtained for non-irradiated conditions. [1] Farias, J., Albizzati, E., Alfano, O., Ind. Eng. Chem. Res., 2007, 46, 7580-7586. [2] Farias, J., Albizzati, E., Alfano, O., Catal. Today, 2009, In Press.