Synthesis of Titania/Silica Nanocomposite for Enhanced Photodegradation of Methylene Blue and Methyl Orange Dyes under UV and Mercury Lights
Ruchi Nandanwar, Jyoti Bamne, Nitu Singh, Preetam K. Sharma, Purnima Singh, Ahmad Umar, Fozia Z. Haque
Abstract
A special sol-gel method is used to successfully synthesize spherical TiO 2 /SiO 2 nanoparticles from titanium tetra-isopropoxide and tetraethoxysilane precursors. The prepared samples were dried at 110 and calcined at 300 , 500 , and 800 . The formed titanium oxide is in a tetragonal structure with significant pure anatase and rutile phase. The estimated particle size of the spherical nanostructure was ~18.40 nm through transmission electron microscopy (TEM) and showed a larger Brunauer Emmett Teller (BET) surface area of 310 m 2 /gm for the sample calcined at 300 . The TiO 2 cores are enclosed within SiO 2 particles with an average crystallite size of 10-20 nm. In atomic force microscopy (AFM) images, the same sample displayed a well-structured and macro-pore-free morphology. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of Ti-O-Ti, Si-O-Si, and Ti-O-Si metal oxide bonds to raise the anatase structure of TiO 2 . The ultraviolet-visible spectroscopy (UV-Vis) of as-synthesized samples reveals the visible absorption region. Photoluminescence spectroscopy (PL) shows a decrease in emission intensity and the emission band splits into sharp peaks to signify the decrease in recombination rate. These properties predict the materials to photo-degrade organic dyes. The material's photocatalytic activity was evaluated for degradation of methylene blue and methyl orange dyes. It is found that the sample calcined at 300 exhibits a better photodegradation for methylene blue (MB, 80-85%) than methyl orange (MO, 70-75%) under mercury light within 2 hours.