Construction of coated Z-scheme Er3+:Y3Al5O12/Pd-CdS@BaTiO3 sonocatalyst composite for intensifying degradation of chlortetracycline hydrochloride in aqueous solution

Abstract

A novel Er3+:Y3Al5O12/Pd-CdS@BaTiO3 composite is successfully fabricated as a coated Z-scheme sonocatalyst. The performance of the prepared Er3+:Y3Al5O12/Pd-CdS@BaTiO3 composite is investigated through chlortetracycline hydrochloride (CTC) degradation. The degradation ratio of CTC can reach 84.02% in the US/Er3+:Y3Al5O12/Pd-CdS@BaTiO3 system for 150 min. Moreover, some affecting factors such as ultrasonic irradiation time, catalyst dosage, initial CTC concentration and used times are considered. The experimental results indicated that the coated Z-scheme Er3+:Y3Al5O12/Pd-CdS@BaTiO3 sonocatalyst displayed outstanding sonocatalytic performance for the removal of CTC in aqueous media under ultrasonic irradiation. In Er3+:Y3Al5O12/Pd-CdS@BaTiO3 composite, CdS and BaTiO3 form a coated Z-scheme sonocatalytic system, some palladium (Pd) nanorods connecting BaTiO3 and CdS as conductive channels promote electrons transfer, effectively suppressing the recombination of electrons and holes pairs. Other some Pd nanorods as co-catalyst can transfer the electrons to its surface. The transferred electrons react with O2, producing O2−. And the BaTiO3 provides a large oxidization surface, which is conducive to CTC degradation. Besides, the up-conversion luminescent material (Er3+:Y3Al5O12) can increase the utilization of light. Finally, a possible sonocatalytic CTC degradation mechanism in the US/Er3+:Y3Al5O12/Pd-CdS@BaTiO3 system is proposed. Perhaps, the coated Er3+:Y3Al5O12/Pd-CdS@BaTiO3 composite is an applicable Z-scheme sonocatalyst to effectively treat the wastewater containing tetracycline under ultrasonic irradiation.