The Comparison of the Photocatalytic Performance Shown by TiO₂ and TiO₂/WO₃ Composites- A Parametric and Kinetic Study.

Kinetic and mechanistic related approaches for mostly titania were intensively studied in the literature. However, combined modelling and kinetic studies are few. Therefore, the present work focuses on modelling the dependence of the degradation kinetics of two model compounds (salicylic acid-SA and methyl orange-MO) on Evonik Aeroxide P25, hydrothermally prepared hierarchical TiO₂ and P25/WO₃ nanostars, obtained also by hydrothermal crystallization. The obtained individual semiconductors and the composites were characterized using XRD, DRS, SEM, while the photocatalytic degradation of the model pollutants were carried out varying the catalyst load, the initial pollutant concentration and incident light intensity. It was found that the degradation kinetics were independent from the hierarchical nature of the material, while significant dependencies of the degradation efficiency was found from the previously mentioned investigation parameters. All these parametric interdependences were successfully studied and a kinetic model was proposed for both bare TiO₂ and TiO₂/WO₃ composite systems.