Kinetic modeling of azo dyes photocatalytic degradation in aqueous TiO2 suspensions

M. LUCILA SATUF; M. JOSEFINA PIERRESTEGUI; RODOLFO J. BRANDI; ORLANDO M. ALFANO

Praga

Encuentro; 6th Encuentro Europeo de Fotocatálisis y Química Solar: Aplicaciones Ambientales (SPEA6); 2010

Institute of Chemical Technology Prague, Academy of Science of the Czech Republic

Azo dyes present in wastewaters from the textile industry constitute a major threat to the environment due to their toxicity, nonbiodegradability and potentially carcinogenic nature. Heterogeneous photocatalysis with titanium dioxide (TiO2) has been proposed as an effective method to degrade this kind of pollutants. Most studies on the photocatalytic degradation of organic species employ reaction rate expressions where kinetic parameters depend on the reactorconfiguration, irradiation source, and operating variables. These kinetic equations are not applicable to different experimental conditions or reactor geometries. Therefore, rigorous reactor modeling involving the evaluation of the radiation field, is essential to obtain intrinsic kinetic expressions that can be used for the design, optimization and scaling up of photocatalytic devices. In the present work, we propose an intrinsic kinetic expression to represent thephotocatalytic degradation rate of the azo dye Acid Orange 7 (AO7). It is based on mechanistic reaction steps and includes the modeling of the radiation absorption effects. The evaluation of the radiation field inside the reactor was achieved by solving the radiative transfer equation for the heterogeneous system, where absorption and scattering take place.