Photodegradation of aqueous reactive dye using TiO₂/zeolite admixtures in a continuous flow reactor

The photocatalytic degradation of an organic dye, i.e. reactive blue 19 (RB19), was studied by employing different TiO₂/zeolite (TZ) photocatalysts, which have TiO₂/(TiO₂ + zeolite) weight ratios ranging from 20 to 80%, in a continuous flow system. Three light sources including two UV lights (i.e. λ_{max,254 nm} and λ_{max,365 nm}) and natural sunlight were used. The results showed that the decoloring rate of RB19 increased as the amount of TiO₂ in the TZ catalyst increased. The photodegradation of RB19 exhibited pseudo-first-order kinetics with respect to the concentration of RB19. Almost 100% of initial RB19 was mineralized under the controlled conditions in this study. And the activities of the prepared photocatalysts were retained after long-term durability experiments. Compared with UV lights (i.e. λ_{max,254 nm} and λ_{max,365 nm}), the decoloring efficiency of RB19 was significantly increased under natural sunlight illumination, which is likely due to the long-wavelength incident light that photoexcited RB19 and accelerated the degradation rate of RB19 radicals by the UV fraction of sunlight.