Investigation on solar photocatalytic degradation of various dyes in the presence of Er 3+:YAlO 3/ZnO–TiO 2 composite

Abstract

In this work, Er 3+:YAlO 3/ZnO–TiO 2 and ZnO–TiO 2 composites were prepared by the ultrasonic dispersion and liquid boiling method. In succession, they were then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Acid red B as a model dye compound was degraded under solar light irradiation to evaluate the photocatalytic activities of the Er 3+:YAlO 3/ZnO–TiO 2 and ZnO–TiO 2 composites. We found that the photocatalytic activity of ZnO–TiO 2 composite can be enhanced by adding an appropriate amount of Er 3+:YAlO 3. We reviewed influencing factors, such as Er 3+:YAlO 3 content, heat-treated temperature and heat-treated time on the photocatalytic activity of the Er 3+:YAlO 3/ZnO–TiO 2 composites. In addition, the effects of solar light irradiation time, dye initial concentration, Er 3+:YAlO 3/ZnO–TiO 2 amount and solution acidity on the photocatalytic degradation of acid red B dye in aqueous solution were investigated in detail. Simultaneously, the degradation and comparison of other dyes such as methyl orange (MO), rhodamine B (RM-B), azo fuchsine (AF), congo red (CG-R) and methyl blue (MB) were also reviewed. In addition, we attempted to explore both the principle of possible excitation of Er 3+:YAlO 3/ZnO–TiO 2 under solar light irradiation and the mechanism of photocatalytic degradation.