Kinetic modeling of sonocatalytic degradation of reactive orange 29 in the presence of lanthanide-doped ZnO nanoparticles

The sonocatalytic degradation of reactive orange 29 (RO29) was examined from the reaction kinetics point of view. Sonochemically synthesized lanthanides (Ho³⁺ and Er³⁺)-doped ZnO nanoparticles were utilized as catalyst during the sonocatalytic process. The prepared nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The aqueous RO29 solution was irradiated with a 36 kHz ultrasonic bath (150 W) for investigation of the degradation kinetics by varying of the initial dye concentration (10-30 mg/L) and catalyst dosage (0.25-1 g/L). A novel kinetic model was developed and validated for prediction of the RO29 sonocatalytic degradation efficiency using generally accepted intrinsic elementary reactions. The proposed kinetic model clearly demonstrates the dependence of the apparent first-order rate constant on the mentioned operational parameters. The predicted values of degradation efficiency and experimental results were in good agreement with appropriate correlation coefficient (R² > 0.945).