Photocatalyst performance in wastewater treatment applications: Towards the role of TiO2 properties

The photocatalytic activity of twelve TiO2 samples prepared by different sol-gel methods have been evaluated in order to comprehensively understand the role of the different TiO2 physico-chemical properties on the catalyst performance. These catalysts have been extensively characterized (analyzed by TEM, XRD, UV-vis, N-2-isotherms, NH3-isotherms, DRIFTS and Laser Diffraction techniques) and tested to analyze the effect of each property by comparing, for example, samples with different rutile contents but with similar anatase crystal sizes and surface areas. The results of this work suggest that best efficiencies can be obtained with samples constituted by only anatase phase and characterized by a relatively high crystal size and a high degree of crystallinity. On the other hand, the results have shown that even though significantly high surfaces areas do not seem to be a prerequisite to achieve the best efficiencies when phenolic pollutants (poorly adsorbed substrates) are evaluated, a certain grade of textural properties must be maintained to keep the surface quality, and a high degree of TiO2 sample dispersion in aqueous media is also desirable to optimize the photocatalytic activity. The results of this work may provide valuable information to design and produce new highly efficient TiO2 photocatalysts materials for wastewater treatment applications. (C) 2017 Elsevier B.V. All rights reserved.