CONICET | Buscador de Institutos y Recursos Humanos

1 IntroductionDichloroacetic acid (DCA) is a pollutant that can be found in water as a byproduct of chlorine disinfection (DBPs). DCA can also be detected in waste waters resulting from the degradation of several chlorinated compounds. In this work the intrinsic reaction kinetics of the photochemical degradation of DCA in aqueous solution employing hydrogen peroxide was studied.2 MethodsThe experimental device was a cylinder, with two parallel, flat windows made of quartz. Each window was irradiated with a tubular, germicidal lamp (Ü 253.7 nm). The small reactor was part of a recycle (Figure 1). Experiments were conducted under different operating conditions. Figure 1: Equipment set up3 ResultsThe proposed reaction path for the degradation of dichloroacetic acid with H2O2/UV is illustrated in Table 2. Table 2: Reaction schemeSteps ReactionInitiation: Propagation: Termination: Decomposition: Using de mass action law and the micro steady state approximation, a kinetic model was developed: (1) (2) is the local volumetric rate of photon absorption (LVRPA) by hydrogen peroxide. The radiation intensity effect was calculated by solving the radiation balance in the experimental reactor.Using the kinetic model, the mass balance for the recycling system and the experimental data, upon application of the Levenberg-Marquardt optimization algorithm, the following kinetic constants were obtained (Figure 5): and with . k2 and k4 were taken from the existing information. (a) (b)Figure 5: Predicted vs. experimental values in the DCA degradation with UV/H2O2. (a): for DCA. (b): for H2O2.4 ConclusionsA kinetic model has been developed to describe the degradation of dichloroacetic acid using hydrogen peroxide plus UV radiation and could be directly used for scaling-up purposes.

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