Kinetics of heterogeneous photocatalytic degradation of rhodamine B by TiO2-coated activated carbon: Roles of TiO2 content and light intensity

The photocatalytic degradation kinetics of rhodamine B (RhB) by TiO2-coated activated carbon (TiO2/AC) catalyst under different reaction conditions (light intensity, TiO2 content in TiO2/AC and initial content of contamination) was elucidated by modeling. The kinetics of Rhb photodegradation was found to follow the first-order rate law and could be described in terms of a modified Langmuir–Hinshelwood model. The value of the apparent rate constant kapp was proposed on the basis of intrinsic element reactions, such as light intensity, reaction intermediates and the photo-induced hole (h±) formation. The apparent rate constant kapp first increased with increasing TiO2 content of the TiO2/AC catalyst and then decreased. The optimal value of the TiO2 content could be obtained through the model; the apparent rate constant was linear with respect to the square of the intensity. The validity of the model was also proved with other researchers’ results.