Author(s)

G Peñuela, G M Mejía, G Hincapié, N Cuervo, J Marín & G M Restrepo

Abstract

The photocatalytic oxidation of methomyl, using Ti02 suspensions under solar radiation and ultraviolet light, has been studied at pilot scale at photodegradation laboratory of University of Antioquia (Medellin, Colombia). Two different reactor designs were tested: a low-concentrating radiation system, Solar- Parabolic-Concentrator Reactor (SPCR), facing south and inclined 6 degrees (geographic position of Medellin: 6 degrees north latitude), and an ultraviolet light system (ULS). Both systems were built in University of Antioquia. In Colombia, methomyl is used as a foliar spray and controls many insects on field crops, fruit crops, and vegetables. Methomyl was dissolved in water to required mg/L levels in a reservoir tank. In both cases, 1 g/L of Lannate (formulation with an active compound: methomyl) was used. TiO2, in concentrations between 50 mg/L and 250 mg/L, and H202, between 1 mL (30%)/L and 3 mL (30%)/L, were used. Aliquots of the water samples were taken at different times of irradiation and total organic carbon (TOC) was analyzed. In some experiments, air was used, without H202, which permitted to compare oxidative efficiency of two oxidant agents (02and H202); both are very used in photocatalytic processes. 79% of mineralization was obtained using SPCR and 52% using ULS. 1 Introduction Degradation of contaminants in water is an area of research interest and, in this sense, sunlight photoalteration processes are known to play an important role [1].

Keywords