Enhancement of sonocatalytic performance of TiO2 by coating Er3+:YAlO3 in azo dye degradation

In this work, the Er3+:YAlO3 as an up-conversion luminescence agent was prepared by sol–gel and auto-combustion method. And then the Er3+:YAlO3/TiO2 composite, a novel sonocatalyst, was successfully synthesized by sol–gel method. The key influences such as amount of coating Er3+:YAlO3, heat treatment temperature and heat treatment time on the sonocatalytic activity of Er3+:YAlO3/TiO2 composites, as well as the amount of Er3+:YAlO3/TiO2 on the sonocatalytic degradation of organic dye was studied. The results indicated that the sonocatalytic activity of TiO2 could be enhanced obviously by coating Er3+:YAlO3. When 1.0 g/L Er3+:YAlO3/TiO2 composite with 50 wt.% amount of coated Er3+:YAlO3 and mixed crystal of TiO2 film was adopted, the highest degradation efficiency was obtained. In addition, the effect of 1-butanol as OH scavenger on the degradation was studied. It showed that the degradation of Acid red B was mainly caused by hydroxyl radical oxidation. Finally, the sonocatalytic degradation of some other organic dyes revealed that the Er3+:YAlO3/TiO2 composite was a widely useable sonocatalyst in treating various dye wastewaters.

► The Er3+:YAlO3 was combined with TiO2 for effectively utilizing sonoluminescence.
► A novel sonocatalyst Er3+:YAlO3/TiO2 was synthesized successfully.
► The Er3+:YAlO3/TiO2 irradiated by ultrasound was used to degrade organic dyes.
► The activity of TiO2 is effectively enhanced by coating Er3+:YAlO3.