Colloidal Processing of Macroporous TiO2 Materials for Photocatalytic Water Treatment

Titanium dioxide (TiO2) is considered one of the most attractive materials during the last decades due to its scientific and technological importance as photocatalyst. There are many reports dealing with several ways of processing TiO2 powders (coatings, tapes, and bulk sinters) and their photocatalytic characterization. However, very little research effort has been devoted to the preparation of macroporous TiO2 ceramics. This work deals with the colloidal processing of TiO2 powders to fabricate porous materials with tailored open macroporosity by direct foaming through gelcasting with polysaccharides. The obtained samples have been characterized through density, microstructure, porosimetry and photocatalytic studies. The effect of the processing parameters: suspension solid loading (20–65 wt%), viscosity, initial particle size (submicrometer and nano‐sized), tensoactive type (cationic, anionic, and non‐ionic), tensoactive content (0.1–1 wt%), and sintering temperature (1000°C–1400°C) onto the properties of the final samples is reported and discussed. Tailored macroporous samples with open porosity (up to 88 vol%) were obtained and they could be used as multifunctional filters with photocatalytic activity for water treatment under UV irradiation. The photocatalytic activity of the final samples depends on the porosity properties, tensoactive content and grain size.