Abatement of organics and Escherichia coli using CeO2-TiO2 composite oxides: Ultraviolet and visible light performances

series of CeO2-TiO2 composite samples were obtained by a single-pot microemulsion method followed by calcination. The composite samples contain fluorite (CeO2) and anatase (TiO2) nanometric phases with a ceria content ranging from 1 to 25 mol%. Using these samples as photocatalysts, toluene mineralization and Escherichia coli 1337-H inactivation were carried out under UV and visible illumination conditions. To interpret the photo-catalytic results and provide quantitative bases to compare the performance of the composite samples with respect to titania and ceria single oxide nano-references the study focuses on analyzing kinetic differences. The kinetic analysis of both types of degradation processes provides conclusive evidence that the composite Ce-Ti system outperforms the Ti reference nano-materials (including P25) by a factor exceeding 3 under UV conditions and 1.7 for sunlight-type or visible light. Together with the low activity of the Ce single reference, the results show that a synergistic effect occurs between the two oxide components of the Ce-Ti system. Maximum activity, irrespective of the chemical or biological target nature as well as the energy of the excitation, was always achieved with samples having low Ce loadings, below 5 mol%. Such a general enhanced activity indicates that the Ce-Ti system can be a "universal" candidate to provide a highly active material with improved performance with respect to nano-anatase. (C) 2014 Elsevier B.V. All rights reserved.