Kinetic Study of Acetaldehyde Photocatalytic Oxidation with a Thin Film of TiO2 Coated on Stainless Steel and CFD Modeling Approach

Removal of low-ppm concentrations of acetaldehyde, a common indoor air pollutant, by photocatalysis is investigated in an annular photoreactor with a thin film of TiO2 coated on a stainless steel plate. Numerical residence time distribution is performed by CFD and characterized with the dispersion model. No byproducts are detected, and complete carbon balance is achieved, allowing the assumption that all of the eventually formed byproducts are converted into carbon dioxide and water. The dependence of the reaction rate on light intensity is studied, showing a first-order tendency in the experimental conditions. Modeling of fluid dynamics and photocatalytic reaction is realized with a CFD approach, considering that intrinsic kinetics is independent of reactor geometry, radiation field, and fluid dynamics. Kinetic parameters determined in a batch reactor are used to calculate the concentration distribution in the annular reactor. In terms of conversion yield, model prediction and experimental results are found in good agreement.