Photocatalytic treatment of phenol and 2,4-dichlorophenol in a solar plant in the way to scaling-up

Abstract

The photocatalytic treatment of phenol and 2,4-dichlorophenol (2,4-DCP) has been tested by using titania in suspension as catalyst. Experiments were done at the solar facilities of the Plataforma Solar de Almerı́a (Spain). Two experimental devices were used: CPCs modules; and flat reactor. Reaction kinetics is order one with respect to the pollutant (phenol or 2,4-DCP) concentration. Two different kinetic constants were fitted from experimental data by considering only time influence on the reaction rate or by considering the radiation influence and assuming that reaction rate is proportional to the square root of photonic flow. In all cases, kinetic constant increases when catalyst concentration does it, reaches a maximum (at 0.5 g/l of catalyst in the CPCs case, and at 0.2 g/l in the flat case), and after this maximum, decreases. When kinetic constants obtained in the two utilities tested are compared, important differences were found when only dependence on time is considered. However, results improve when radiation influence is considered, and the values obtained in both devices are more close. This fact indicates the influence of reactor geometry and radiation on the reaction rate, and their importance in the scaling-up. Finally, the efficiencies of CPCs and flat reactor are compared attending to the collector area needed to obtain the same conversion in the pollutant treatment. It seems that CPCs work better, however several factors can influence (for instance, weather: cloudy or sunny days) and more accurate studies are needed.