Adsorption Behavior of Nano Sized Sol-Gel Derived TiO2-SiO2 Binary Oxide in Removing Pb2+ Metal Ions.

Nanostructure Titania-Silica (TiO2/SiO2) binary mixed oxide was synthesized using titanium tetra chloride and tetraethylorthosilicate as starting materials. The resulting powder was characterized by thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray powder diffraction (XRD), X-ray fluorescence spectroscopy (XRF), infrared spectroscopy (IR), transmission electron microscope (TEM), and nitrogen gas adsorption studies. The XRD and BET surface area showed that the Titania-Silica binary oxide was crystallized in the anatase and brookite phases and had a BET surface area of 405.3 m2/g. Distribution coefficient of Pb2+ ions in solid and liquid phases were investigated by means of batch experiments. Several parameters such as the contact time and the pH of the solution, which could affect the magnitude of adsorption, were examined. Sorption data have been interpreted in terms of the Freundlich and Langmuir equations. The results of free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) showed that the sorption of Pb2+ on TiO2-SiO2 is an endothermic and a spontaneous process. [ABSTRACT FROM AUTHOR]