Solar photocatalytic degradation of methyl orange dye using TiO2 nanoparticles synthesised by sol-gel method in neutral medium

摘要

Anatase TiO2 nanoparticles were synthesised by the sol-gel method in neutral medium, and its photocatalytic activity in the degradation of methyl orange dye under sunlight has been studied. The nanoparticles were characterised using high-resolution X-ray diffraction, high-resolution transmission electron microscopy, micro Raman analysis and diffuse reflectance spectroscopy. The blueshift and asymmetrical broadening associated with phonon confinement effect has been observed in the Raman spectra of pristine nanoparticles. The high temperature annealing of as prepared anatase samples resulted in the phase transformation in to rutile. The mixture of anatase and rutile TiO2 nanoparticles exhibited faster photocatalytic activity in the degradation of methyl orange than the pristine anatase and rutile phases. The significant enhancement in the photocatalytic activity of mixed TiO2 nanoparticles is due to the synergistic effects that consist of the antenna effect by the rutile phase and the activation effect by the anatase phase. Since method of preparation of the catalyst is comparatively simple and cost effective, and the energy source used is sunlight, the method can be easily implemented in waste water treatments.