Photocatalytic Degradation of Some Pesticides and Polycyclic Aromatic Hydrocarbons by Metal Doped Titania Nanoparticles

Abstract

Photocatalysis is an area of immense research for finding suitable benign photocatalyst for fast and complete mineralization of environmental pollutants such as pesticides and polycyclic aromatic hydrocarbons. Undeniably, TiO2 specifically P25-TiO2 which is commercially available TiO2 have been widely studied for the same, however suffers from some disadvantages such as crystal phase transformation at high temperature, UV-light sensitivity and low percentage of mineralization of above mentioned molecules, limiting its utilization. This creates a scope to modify TiO2 and/or to find other Ti-O based materials possessing similar physicochemical properties but with improved photocatalytic activity for decomposition of aforementioned molecules. In this context, present work considers the synthesis of titania/titanate nanostructures in different sizes, shapes, crystal structures which were loaded by metals/coated by SiO2 of different shell thickness and studied for the decomposition of some pesticides and polycyclic aromatic hydrocarbons to CO2 in comparison to P25-TiO2. Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalytic research. Despite having sodium (Na) content and its high temperature synthesis (that generally deteriorate the photoactvity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, chapter-3 demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotubes and titania nanorods. Straw like hollow orthorhombic nanotube (Na2Ti2O5·H2O) particles (diameter = 9-12 nm and length = 82-115 nm) and rice like anatase nanorod particles (diameter = 8 13 nm and length = 81-134 nm) were obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of these as-prepared nanoparticles.