New titania-clay nanostructured porous materials

Abstract

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 organoclays 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 TiO 2 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 TiO 2/SiO 2-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 29Si 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® anatase, reaching up to twofold activities per unit mass for some of the nanostructured porous solids developed here.