Textile Dye Removal Using a Photocatalytic Cascade Disc Reactor Coated by ZnO Nanoparticles: Effects of Hydraulic Parameters

Hydraulic parameters play an important role in mass transfer phenomena in photocatalytic reactors. These fundamental hydraulic parameters are flow rate, relative roughness, and Reynolds number. This research experimentally evaluates the effects of flow rate and artificial relative roughness in order to determine the factors influencing the removal efficiency and reaction rate constant of Reactive Yellow 81 (RY81). For this purpose, a cascade photocatalytic reactor is constructed which consists of similar polymethylmethacrylate plates coated by ZnO nanoparticles and with various types of roughness. Dye removal efficiency is calculated for different flow rates with and without considering relative roughness. Furthermore, this study also reveals main effective parameters increasing the mass transfer rate, and uses a decision tree model called M5-Pruned (M5P) for predicting dye removal efficiency. Therefore, simple relations are provided for calculation of dye removal efficiency that consider important parameters including flow rate, run-time, roughness height, and initial pollution concentration.