Role of pH on the photocatalytic activity of TiO2 tailored by W/T mole ratio

Tailoring of TiO2 properties by controlling W/T mole ratio (70, 140, 210 and 280) was carried out by sol-gel method using TTIP as Ti precursor and H2O as O-2 precursor. The anatase phase evolution with Ti and O-2 composition variations was verified, respectively, through X-ray diffraction and EDX analysis. The spherical topography of TiO2 particles was elucidated by FESEM, which was noticeably affected with W/T mole ratio. The quantitative measurement of particles' size, shape and their distribution were directly observed at a scale approaching a bunch of atoms by HRTEM. The numerical values of crystallite size and particle size, as measured by the XRD peak broadening and TEM techniques, differ slightly. The optical study, by UV-Visible spectroscopy, registered blue shift in the absorption edge wavelength of TiO2 as well as increase in the band gap energy, with increase in W/T mole ratio. The presence of functional groups at the interface of TiO2 nanoparticles was confirmed by FTIR. Considering MB dye as a model pollutant, the characterization of photo-oxidation kinetics was also performed to assess the effect of pH and W/T mole ratio on removal efficiency of TiO2. Excellent photocatalytic performance of TiO2-70 R under UV light irradiation for 180 min was observed at a pH of 11; the corresponding photocatalytic kinetics, denoted by first order degradation rate constant (Kappa) was found to be approximately 0.00404 min(-1).