Degradation of azo dye in wastewater using mesoporous-assembled SrTixZr1-xO₃ (x=0-1) nanocrystal photocatalysts

Abstract

An azo compound is a synthetic dye comprising one or more azo groups (-N = N-) linked between aromatic rings. The release of this coloring agent unavoidably causes wastewater treatment problems. Photocatalysis is an effective method that uses sunlight as the energy source to degrade the azo dye under ambient conditions. This research focused on the improvement of photocatalytic activity of mesoporous-assembled SrTixZr₁-xO₃ nanocrystal photocatalysts for Acid Black (AB) diazo dye degradation by varying the Ti-to-Zr molar ratio, calcination temperature and time, and platinum (Pt) loading content. 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 SrTixZr₁-xO₃ nanocrystal with a Ti-to-Zr ratio of 0.9: 0.1 calcined at 700 ℃ provided a better degradation rate constant than others. Pt loading with an optimum content on the mesoporous-assembled SrTi₀.₉Zr₀.₁-xO₃ nanocrystal was found to increase the degradation rate constant of the AB diazo dye. Furthermore, the calcination temperature was found to significantly affect the degradation rate constant.