Kinetic investigation of nanophotocatalytic reaction (ZnO-Ag-Zr) in the degradation of reactive red dyes (RR198)

In this research, a photocatalytic reactor made of quartz was designed and built. Then ZnO nanophotocatalysts modified with different percentages of Ag and Zr were synthesized by combustion method and using microwave. Photocatalytic experiments showed that nanophotocatalysts with a mass ratio of 0.093 Ag and 0.04 Zr are more efficient. The characteristics of this catalyst were evaluated by XRD, SEM and FT-IR analyses. Then the photocatalytic activities of ZnO-Ag-Zr in the degradation of reactive red dye 198 were investigated and the effective factors such as pH of the solution, amount of catalyst and initial concentration of the solution were investigated. Experiments showed that the optimal conditions for decolorization of the dye at a concentration of 20 mg/liter are: pH=10 and the amount of catalyst is 0.3 g/liter, and under these conditions, decolorization is above 92%. Also, in the study of the kinetics of the aforementioned reaction, it was shown that the removal rate of Reactive Red 198 dyes is in good agreement with the pseudo-first-order Langmuir-Hinshelwood equation, and therefore, the kinetic parameters were determined using this model.