New titania-clay nanostructured porous materials

New nanostructured titania-clay porous materials were prepared following a colloidal route that involves the controlled hydrolysis and polycondensation of titanium (IV) isopropoxide in the presence of organo-clays prepared from various layered silicates (montmorillonite, iron-rich smectite and vermiculite) treated with cetyltrimethylammonium bromide. Heating the resulting materials to eliminate the organic matter produces TiO2 nanoparticles (anatase phase) homogeneously dispersed within the delaminated clays. The use of alkoxide mixtures containing the titania precursor together with tetramethoxysilane, as a silica precursor, also gives delaminated silicates containing in this case TiO2/SiO2-clay materials. All the resulting materials were characterized by means of XRD, FTIR, thermal (TG-DTA) and chemical analyses, specific surface area and porosity determinations, TEM, SEM-EDX and Si-29 NMR techniques. Photocatalytic activity of these new porous materials was studied using the 2,4-dichlorophenol decomposition in an aqueous solution as a reaction test. The activities and kinetics of the decomposition processes are comparable and even superior to that of the commercial P25(R) anatase, reaching up to twofold activities per unit mass for some of the nanostructured porous solids developed here. (C) 2010 Elsevier Inc. All rights reserved.