Photocatalytic Penicillin Degradation Performance and the Mechanism of the Fragmented TiO2Modified by CdS Quantum Dots

Abstract

In this study, a novel method was adopted to construct a CdS-TiO2 heterostructure to degrade penicillin under sunlight. A potato extract was used during the synthesis process of CdS QDs as a stabilizer and a modifier. The CdS-TiO2 composite with a heterostructure delivers high photocatalytic degradation efficiency. In detail, 0.6 mg/mL of CdS-TiO2 can successfully decompose penicillin after 2 h, and 5‰ CdS-TiO2 shows the optimal degradation efficiency with the degradation rate reaching 88%. Furthermore, the underlying mechanisms of the penicillin decomposition reaction were investigated by the EPR test and trapping experiment. It was found that the high photocatalytic degradation efficiency was attributed to the heterojunction of CdS-TiO2, which successfully suppresses the recombination of the conduction band of CdS and the valence band of TiO2. Moreover, it was confirmed that the reaction is the O2-consuming process, and introducing O2 can greatly accelerate the generation of a superoxide radical during the photocatalytic degradation process, which eventually improves the degradation of penicillin and shortens the degradation time. Finally, this work provides the possible penicillin degradation pathways, which will inspire the researchers to explore and design novel photocatalysts in the field of wastewater treatment in the future.