An investigation into the effect of porosities on the adsorption of rhodamine B using titania-silica mixed oxide xerogels.

Aperiodic mesoporous titania-silica (TiO2·SiO2) xerogels with varying silica contents were synthesized under ambient conditions. The physico-chemical properties of the xerogels were examined by a variety of techniques that include powder X-Ray Diffraction (XRD), nitrogen adsorption, Fourier Transform-Infra-Red spectroscopy (FT-IR), Scanning and Transmission Electron Microscopies (SEM and TEM), Thermo Gravimetric Analysis (TGA), zeta potential, and Diffuse Reflectance Spectroscopic (DRS) studies. The adsorption of a model dye molecule, rhodamine B (RhB) was studied over the titania-silica xerogels and compared with titania and silica. It was determined that the pore volume of the xerogels mainly influences the adsorption of RhB. The xerogels exhibited good adsorption capacity with more than 90% dye removal at low dye concentrations. Our results suggest that low cost approaches to the synthesis of xerogels with tailored properties such as large pore volume could provide cost-effective solutions to mitigate environmental problems related to removal of water based toxic pollutants such as dyes by simple adsorption processes.