KINETIC STUDY OF THE FENTON AND PHOTO-FENTON DEGRADATION OF A HERBICIDE IN WATER

BENZAQUÉN, TAMARA B.; ISLA, MIGUEL A.; ALFANO, ORLANDO M.

Guadalajara

Congreso; 2nd. Latin-American Congress on Photocatalysis - Guadalajara 2013..; 2013

Universidad de Guadalajara, México - Centro Universitario Tonalá

Traditional treatment methods, like the biological methods result ineffective to degrade some recalcitrant organic pollutants due to their resistant to biodegradation (Konstantinou et al., 2004¸ Bacardit et al., 2007; Chen et al., 2009). The Advanced Oxidation Processes (AOPs) are known by their capacity for oxidizing and mineralizing a great variety of toxic and non-biodegradable compounds. Therefore, AOPs, such as the Fenton or photo-Fenton processes, appear as effective alternative methods to treat recalcitrant organic pollutants like the herbicide atrazine (Benzaquén et al., 2013). This study is focused on the kinetic modeling of the Fenton and photo-Fenton degradation of a model pollutant (atrazine) in aqueous solution. The experimental work was performed in a well stirred tank laboratory reactor irradiated from both sides with two tubular UV-lamps. The reaction rate expressions are derived from an accepted reaction mechanism and explicitly having into account the local volumetric rate of photon absorption. Figure 1 shows predicted and experimental concentrations for all the Fenton and photo-Fenton runs performed in the kinetic study. The symbols correspond to the atrazine and hydrogen peroxide concentrations obtained under different operating conditions. Model predictions were compared with experimental data, and a good agreement was obtained, with a root mean square error (RMSE) of 1.38 % for the Fenton system and a RMSE of 1.34 % for the photo-Fenton system. For all the investigated Fenton and photo-Fenton experimental runs, and considering atrazine and hydrogen peroxide concentrations, the maximum RMSE of the estimations was 1.36%. Besides, model predictions and experimental results of atrazine concentration as a function of the reaction time, for Fenton and photo-Fenton systems, were compared for different ferric iron concentrations and hydrogen peroxide to atrazine initial molar ratios. Additionally, it was found that the photodegradation process clearly enhanced the biodegradability of the samples. Consequently, these AOPs could be used as a pre-treatment method to degrade bio-recalcitrant herbicides.