Chemical Engineering Journal 167 (2011) 42–49 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej Removal of ten pesticides from leaching water at pilot plant scale by photo-Fenton treatment Simón Navarro a,∗ , José Fenoll b , Nuria Vela c , Encarnación Ruiz b , Ginés Navarro a a Departamento de Química Agrícola, Geología y Edafología. Facultad de Química, Universidad de Murcia, Campus Universitario de Espinardo, 30100 Murcia, Spain b Departamento de Calidad y Garantía Alimentaria, Instituto Murciano de Investigación y Desarrollo Agrario y Alimentario (IMIDA), C/Mayor s/n. La Alberca, 30150 Murcia, Spain c Facultad de Ciencias de la Salud, Universidad Católica San Antonio de Murcia, Campus de Los Jerónimos, s/n. Guadalupe, 30107 Murcia, Spain article info Article history: Received 13 October 2010 Received in revised form 29 November 2010 Accepted 29 November 2010 Keywords: Agrochemicals Fenton’s reagent Groundwater pollution Photooxidation Solar photocatalysis abstract The protection and remediation of groundwater resources is a priority of EU environmental policy. With this aim, the degradation of ten pesticides in leaching water at pilot plant scale by photo-Fenton treatment under natural sunlight is reported. The solar pilot plant placed in Murcia (SE Spain) is based on compound parabolic collector (CPC) technology. The agrochemicals, commonly used on pepper protection belonging to different chemical groups were azoxyxtrobin, cyprodinil, fludioxonil, kresoxim-methyl, hexaconazole, tebuconazole, triadimenol, and pyrimethanil (fungicides), primicarb (insecticide), and propyzamide (her- bicide). All pesticides were found in leachates under laboratory and field conditions although at different rates. Pesticides were added to leaching water (150 L) at 0.5 mg L -1 and the ratio ([Fe 2+ ]/[H 2 O 2 ]) of Fen- ton’s reagent (FR) at 0.5 was selected. Several samples were taken during the photoperiod (60 min). As expected, the influence of the treatment was very significant in all cases. Photocatalytic experiments show that the addition of FR strongly enhances the degradation rate of the pesticides in comparison with photolytic tests. The disappearance time (DT 50 ) ranged from 2 to 5 min. The first-order equation (monophasic model) ignores small residues remaining late in the dissipation process. These residues are important from an environmental point of view and the Hoerl function (biphasic model) better predict the results obtained. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Under certain conditions, some pesticides may leach to ground- water from usual field applications [1]. Groundwater pollution not only affects the health of humans being as it is being used for drinking purpose, but also can act as a source of contamination for food chain, when used for irrigation. Although there is large literature concerning groundwater pollution, predicting pesticide behavior in subsurface geosystems remains a complex scientific and practical problem. Pesticide residues have been retrieved in groundwater bodies all over the world and their levels frequently exceed the drinking water limit set by the EU where the protec- tion of groundwater resources is a priority of its environmental policy. Thus, on October 2000, the EU Water Framework Directive (WFD, 2000/60/EC) was adopted and three years later, on Septem- ber 2003, the European Commission adopted a proposal for a new Directive to protect groundwater from pollution and deterioration (2006/118/EC) in whose Annex I, the quality standards for pesti- cides and metabolites are listed. ∗ Corresponding author. Tel.: +34 868 887477; fax: +34 868 884148. E-mail address: snavarro@um.es (S. Navarro). The environmental fate of pesticides depends a lot on their mobility in soils and their tendency to partition into other environ- mental compartments, such as air and water. Transfer processes move pesticides in the environment. Concretely, leaching (the movement of water and dissolved chemicals through the soil) of pesticides through the soil profile from agricultural practices is receiving increasing attention [2]. In the leaching process, the physicochemical properties of the agrochemicals used as well as soil properties (texture, clay content, organic matter content and permeability) play a decisive role [3]. The necessary use of pesticides in intensive agriculture has important effects on the quality of environmental water. How- ever, many of them (toxic or refractory) are not amendable to microbial degradation and other more effective technologies such as advanced oxidation technologies (AOTs) like Fenton processes, ozonation, photochemical and electrochemical oxidation, photoly- sis with H 2 O 2 and O 3 , semiconductor photocatalysis (mainly TiO 2 ) and others have been proposed for treatment of polluted water by pesticides [4–9]. In this context, the use of Fenton and related reac- tions encompass reactions of peroxides (usually H 2 O 2 ) with iron to form active oxygen species that oxidize organic or inorganic com- pounds when they are present. Fenton-type systems employing Fe 2+ or Fe 3+ and H 2 O 2 are a source of hydroxyl radicals (HO • ), one 1385-8947/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.cej.2010.11.105