Impact of the experimental conditions and of the physicochemical parameters of TiO2 on the photocatalytic transformation of acetic acid

SSCI-VIDE+CARE+CGU:FDAInternational audienceThe impact of the photonic flux, humidity, atmosphere (air or oxygen-free atmosphere), and flow rate on the disappearance, mineralization and intermediate products of the transformation of acetic acid has been studied in the presence of TiO2 P25. It was found that whatever the conditions, decarboxylation is the first step of AA degradation. However, the fate of the methyl group depends on the atmosphere, the gas phase concentration and the conditions. In air, the methyl group is oxidized into methanol, formaldehyde, and CO2 with no formic acid detected and, depending on the photonic flux, ethane is also detected. In an O2-free atmosphere, three new products were observed: methane (CH4), acetone (CH3COCH3) and acetaldehyde (CH3COH). In the both atmospheres, the presence of humidity strongly increases the conversion and the mineralization of acetic acid. Mechanisms of the formation of products are proposed in presence or absence of oxygen together with the regeneration of the TiO2 surface and the formation of H2O2. Finally, the impact of the nature of TiO2 (pure anatase and mixture of anatase/rutile), of the impurity and of the surface area have been investigate