Efficient application of nano-TiO2 thin films in the photocatalytic removal of Alizarin Yellow from aqueous solutions

Abstract

The aim of this investigation is to obtain thin films of nano-TiO2 on a borosilicate glass substrate using sol–gel template method. The thin film was immobilized with and without polyethylene glycol as filler media and annealed at 500°C. Further, thin films were characterized by the IR, XRD, XRF and XPS analytical methods. The surface morphology of these films was obtained by the FE-SEM images and the BET specific surface area and pore sizes were obtained. The nano-TiO2 was, perhaps, formed a nanopillar onto the substrate. The thin films were successfully employed in the photocatalytic degradation of Alizarin Yellow (AY), an azo dye, from aqueous solutions using the UV-light irradiation under batch reactor operations. Various physico-chemical parametric studies, viz., effect of pH, Alizarin Yellow concentration and interfering ions were studied to deduce the mechanism involved in photocatalytic degradation of this pollutant. The time dependence degradation of Alizarin Yellow was provided to demonstrate the kinetics of degradation of this pollutant from aqueous solutions. It was observed that the degradation of Alizarin Yellow followed pseudo-first-order rate kinetics. Study was further extended with total organic carbon measurement using TOC analyser to demonstrate an apparent mineralization of Alizarin Yellow from aqueous solutions. The presence of several interfering ions or even OH scavengers suppressed the photo-catalytic action of thin films in AY degradation from aqueous solutions.