Synthesis of mesoporous TiO2 and its role as a photocatalyst in degradation of indigo carmine dye

Abstract

A modified sol–gel route without the use of acid or base was used to synthesize mesoporous TiO2 catalyst which was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force spectroscopy, optical absorption spectroscopy and Brunauer–Emmett–Teller adsorption isotherm technique. The synthesized mesoporous TiO2 is highly crystalline, pure and consisting of very high porosity and surface area 226.25 m2 g−1. The catalyst showed an excellent photocatalytic activity against the degradation of indigo carmine in the presence of visible light. It was found that 50 mL dye solution of 4 × 10−5 M concentration has been completely degraded and decolorized with optimum catalyst dose of 1.5 g/L in 180 min, acidic pH and at 25 ± 1 °C reaction temperature. The reaction kinetic was studied, and it was found that the indigo carmine dye photocatalytic degradation followed pseudo first-order reaction kinetics with rate constant, k of 0.007 min−1. Degradation of dye was confirmed by chemical oxygen demand analysis and UV–Vis spectrophotometry.