Synthesis and Characterisation of Silica-Modified Titania for Photocatalytic Decolouration of Crystal Violet

In the past few years, silica-modified titania has drawn increasing attention due to their special properties making them ideal candidates for a wide range of applications. In this study, we report a novel method for the synthesis of silica-modified titania by a sol–gel method using sodium silicate solution (1 M). The hydrolysis and condensation reactions of titanium dioxide (TiO₂, Degussa Aeroxide^® P25) in sodium silicate solution proceeded with citric acid (3 M) as a catalyst. The orbital shaking method was followed for the removal of sodium salt formed during the sol–gel process. Solvent exchange was carried out using methanol and hexane. Finally, chemical modification of the gel was conducted using trimethylchlorosilane followed by ambient pressure drying. The obtained silica-modified titania was characterised for nanostructural analysis using scanning electron microscopy and transmission electron microscopy. The nitrogen adsorption–desorption measurements were employed to investigate the BET surface area, pore structure and pore volume of specimens. Thermal gravimetric analysis showed exothermic peaks at temperature range of 90–190 °C representing the oxidation of organic groups from –Si–R network. The silica-modified titania showed high photocatalytic activity and an easy recovery using crystal violet as model water pollutant.