Phenol degradation over mesoporous-assembled SrTixZn1-xO₃ nanocrystal photocatalysts

Abstract

Advanced oxidation processes (AOPs) are effective techniques used to efficiently degrade non-biodegradable organic contaminants present in wastewater. Photocatalysis is an AOP that is very promising in the use of solar energy to initiate degradation reactions. The most interesting photocatalyst is SrTiO3 since it is chemically stable, non-toxic, and highly active in hydrogen production. In this work, mesoporous-assembled SrTixZn1-xO3 nanostructure photocatalysts were synthesized by a sol-gel method with the aid of a structure-directing surfactant. The Ag, Cu, and Pt loadings on SrTixZn1-xO3 were carried out by the photochemical deposition method. The synthesized photocatalysts without and with different metal loadings were tested for the degradation of phenol, which was used as a model contaminant in water. The effects of various synthesis parameters, such as the ratio of Ti:Zn, calcination temperature, and metal loading content, on photocatalytic phenol degradation performance were investigated. The mesoporous-assemble photocatalyst SrTixZn1-xO3 nanostructure photocatalyst with a Ti-to-Zn molar ratio of 0.97:0.03 calcined at 700 °C provided the highest phenol degradation rate constant (k) of 0.80 h-1. Among the studied loaded metals, Pt provided the highest photocatalytic activity toward phenol degradation. Therefore, O2 gas could enhance the reaction rate constant of 0.5 wt.% Pt on SrTi0.97Zn0.03O3 photocatalysts from 0.94 to 0.97 h-1.