Influence of activated carbon in TiO2 and ZnO mediated photo-assisted degradation of 2-propanol in gas-solid regime

2-Propanol was photocatalytically oxidized in the presence of binary materials composed by mixtures of home-prepared active carbon and commercial TiO2 or ZnO. Remarkable beneficial improvements of the photocatalytic activity were observed in the presence of activated carbon (AC). In particular the presence of AC along with TiO2 in the binary materials enormously increased the photocatalytic ability of the bare semiconductor to completely oxidize the substrate, indicating a synergy between the semiconductor and AC. Probably, when AC was present in the binary materials, the majority of the substrate and of the intermediates were reversibly adsorbed onto the AC surface. Due to the presence of a contact interface between TiO2 and AC, a continuous transfer of the species from the AC to the TiO2 surface was possible. On the other hand, the presence of AC avoided the deactivation of TiO2 that occurred instead for the bare semiconductor. The reaction rate in the presence of ZnO based materials was always lower with respect to that observed for the corresponding TiO2 ones, although the presence of AC improved the photoactivity of bare semiconductor in this case also. (C) 2010 Elsevier B.V. All rights reserved.