Study Degradation of 4-(2-Pyridylazo)Resorcinol Dye in Circulating Fludized Bed Photo Reactor Using ZnO Nanoparticles

Background & Aims of the Study: In this study, 4-(2-pyridylazo) resorcinol (PAR) as model azo dye was used. In spectroscopic measurements and studies of PAR reagent as a ligand are used to formation a complex with toxic metals. So, removal and degradation these compounds of wastewaters are necessary. The aim of this study is the degradation of PAR from aqueous solutions in circulating fludized bed photo reactor (CFBPR) using ZnO powder. The UV/O2 system was used for dye degradation. Materials & Methods: ZnO powder used a catalyst for the degradation of dye in aqueous solution. ZnO powder has been characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The effect of operational parameters such as: pH, catalyst dosage and temperature were studied. The effect of UV irradiation, UV/O2 and UV/O2/ZnO on photocatalytic degradation of PAR were studied. The reaction kinetic was studied. The optimum conditions were determined using design of experimental based one factor at the time (OFAT) method. Results: The optimum conditions for this reaction were obtained at pH=10, catalyst dosage=20 mg/L, and temperature=40°C. The pseudo first order reaction with rate constant (k=0.0105 min−1) in T=40°C was observed for the photocatalytic degradation of PAR. Activation energy (Ea) for the degradation of PAR was obtained as 48.12 (kJ/mol). These experiments demonstrated that UV/O2 and ZnO catalyst were needed for the effective degradation of dye. Conclusions: The results showed that the photocatalytic process can be suitable to degradation PAR dye from aqueous solutions using ZnO catalyst.