Dependence of the rate of photocatalytic decomposition of safranine on the catalyst concentration

The effect of the concentration of disperse titanium-containing oxide photocatalysts on the decomposition of safranine in aqueous solution was studied. The observed decomposition rate constant of safranine increases with increasing catalyst content in the solution and reaches a maximum at catalyst concentration a parts per thousand currency sign3 g/L, after which this constant no longer depends on the catalyst content. The plateau for the rate constant results from light scattering and narrowing of the reaction space due to increased optical density of the solution. An increase in the specific catalyst surface is observed in the region of a rising rate constant with increasing catalyst concentration, while no such dependence is found in the plateau region.