Kinetics of the photocatalytic degradation of methylene blue on titanium dioxide

The first step of the photocatalytic degradation of methylene blue (MB) on anatase is photocatalytic reduction with subsequent decomposition of the dye itself and its leucobase. At low catalyst concentrations (≤2 g/L), the dye decomposition rate constant increases with increasing anatase concentration. A plateau appears for anatase concentrations above 2 g/L. Under steady-state conditions, the reaction kinetics is described by the Michaelis–Menten equation if the catalyst concentration is significantly greater than the MB concentration, which permits us to determine the kinetic parameters of the degradation process.