SYNTHESIS AND CHARACTERIZATION OF NANOPOROUS TiO 2 FOR ENVIRONMENTAL APPLICATIONS

Abstract

Titanium dioxide is being synthesized by a number of procedures by the researchers and industrialists. Among all these procedures, sol-gel is the most popular and the simplest one. Sot-gel method can be used along with templating process to prepare highly porous titania with a very high specific surface area. Calcium alginate was used as a biopolymeric template. Calcium chloride concentration was varied for a fixed weight percent of sodium alginate in order to get the optimum ratio for preparing the template calcium alginate beads. Similarly effect of varying the TIP (titanium isopropoxide)/lPA (Isopropanol) ratio was also studied using SEM analysis. In fact varying these concentrations did not affect the crystallinity of the titania nanoparticles much but they did affect the shape, size and porosity of the porous titania microspheres. The prepared samples were characterized by UV-visible spectroscopy, diffused reflectance spectroscopy (DRS), X-ray diffraction (XRD) and scanning electron Microscopy (SEM). These results demonstrated that the titania beads were almost spherical in shape after calcination. Pore size and surface area measurements were done using BET pore size and surface area analyser. Nitrogen adsorption-desorption isotherm concluded that mesoporous microspheres having a high surface area of 228 m2/g were formed. Photocatalytic activity was evaluated by photocatalytic degradation of Trypan Blue dye. These nanoporous beads were further used for environmental applications such as adsorption of heavy metal ion (Pb 2) and organic dye (methyl blue). Analysis using Atomic Adsorption Spectroscopy concluded that a sufficient amount of lead ions were adsorbed while desorption of lead ions were almost 100%. UV-Vis Spectrophotometer was used to analyze adsorption of Methyl Blue on the titania beads. Because of its sufficiently larger size, separation and filtration of adsorbent from the solution was very easy.