Cinética de la degradación fotocatalítica del ácido dicloroacético

CRISTINA S. ZALAZAR, ROBERTO ROMERO, CARLOS MARTÍN Y ALBERTO E. CASSANO

Mérida, Mexico

Simposio; XIX Simposio Iberoamericano de Catálisis; 2004

The photocatalytic oxidation of low concentration, aqueous solutions of dichloroacetic acid(DCA) was studied employing 2 TiO , UV radiation and oxygen.Using the mass action law and the micro steady state approximation, a kinetic model wasdeveloped starting from a complete reaction sequence based on the direct hole attack of DCA.The obtained kinetic representation gives reaction rates for the DCA disappearance and thechloride ion formation that include the local rate of photon absorption (LVRPA) and requireonly two kinetic parameters. The LVRPA are obtained solving the radiative transfer equationfor the whole reaction space. A flat-plate, one-dimensional model was proposed andnumerically solved employing the Discrete Ordinate Method. The employed reactor was acylinder of 110 cm3 irradiated from both sides with tubular lamps (Philips HPA1000) andparabolic reflectors. The reactor was part of a recycling system. Experiments were conductedunder different operating conditions. The mass balance for DCA degradation and chloride ionformation was closed with very small error, indicating that in an aqueous medium there are nostable intermediate reaction products. The following kinetic constants were obtained:10 . 0 53 . 0 * ?} = ƒ³ mol/Einstein and 03 10 ) 60 . 0 43 . 4 ( kObs − ?~ ?} = mol /cm3 s.