Photocatalytic activity of kaolinite

The photocatalytic activity of commercial kaolinite (KGa-1b) was evaluated for the degradation of methylene blue (MB) in aqueous suspension and of toluene in the gas phase. An enhanced photolysis of MB in the presence of kaolinite was detected, albeit at a slower rate than in the presence of the same mass of commercial TiO₂ P25. Toluene removal under realistic ambient concentrations was catalyzed by both KGa-1b and P25; however, on a TiO₂ content normalized basis, the clay mineral showed a higher photocatalytic rate. In the latter case, toluene degradation was found to be coupled to the presence of kaolinite surfaces, and not proportional to TiO₂ content.