TiO2 deactivation processes during gas-phase degradation of ethanol were studied. To force the deactivation processes, various cycles were performed, avoiding the degradation of acetates. It was observed that acetates adsorbed on the anatase phase of catalysts provoke the transference of electrons to surface traps which modify the electron states of the semiconductor. The same deactivation studies were also performed with fluorinated TiO2. It was noted that the electrons present in the surface traps, as a consequence of the Ti-F interaction, react with the holes during irradiation and provoke a change in the electron states of the semiconductor. (C) 2017 Elsevier B.V. All rights reserved.