Photocatalytic degradation of Azo Dye contaminant in Wastewater using mesoporous-assembled In₂O₃-TiO₂-mixed oxide photocatalysts

Abstract

Am azo compound is an important class of synthetic dyes and is characterized by the presence of one or more azo group (-N=N-) linked between aromatic rings. The release of this coloring agent causes wastewater problems. Photocatalysis is an efficient technique to remove dye pollutants because of several advantages. This work focused on the improvement of the photocatalytic activity of mesoporous-assembled In₂O₃-TiO₂ mixed oxide photocatalysts for Congo Red (CR) azo dye degradation by varying In₂O₃-to-TiO₂ molar ratio, calcination temperature, and silver (Ag) loading. All of the photocatalysts were synthesized by a sol-gel process with the aid of a structure-directing surfactant. The experimental results showed that the mesoporous-assembled In₂O₃-TiO₂ mixed oxide photocatalyst with an In₂O₃-to-TiO₂ molar ratio of 0.05:0.95 calcined at 500°C provided the highest CR degradation rate constant of 0.86 h⁻¹. In addition, the optimum Ag content of 1.5 wt% loaded on the mesoporous-assembled 0.05In₂O₃-0.95TiO₂ photocatalyst by a photochemical deposition method was found to increase the CR degradation rate constant to 1.37 h⁻¹.