Sonocatalytic removal of tetracycline in the presence of S-scheme Cu2O/ BiFeO3 heterojunction: Operating parameters, mechanisms, degradation pathways and toxicological evaluation

The development of efficient sonocatalysts is of great significance to the treatment of antibiotic wastewater. Herein, an S-scheme sonocatalyst Cu2O/BiFeO3 has been fabricated using a simple synthesis method, in which Cu2O nanoparticles grow on the surface of BiFeO3. Tetracycline (TET) was selected as a representative pharmaceutical model to systematically evaluate the sonocatalytic performance of the Cu2O/BiFeO3. The experimental results showed that optimized Cu2O/BiFeO3 (CBF-3) has superior sonocatalytic performance to TET (98.0 %, 0.02302 min- 1), which is much higher than that of pure BiFeO3 (54.6 %, 0.00515 min- 1). Combined with the experimental result and characterization analysis, the sonodegradation mechanism was discussed. The improved sonocatalytic performance can be ascribed to the S-scheme charge transfer mechanism between Cu2O and BiFeO3, which can simultaneously inhibit sonoelectron-hole recombination, promote carrier transfer, maintain high redox capacity, and generate more active substance. The possible intermediate products and degradation pathways of TET over CBF-3 were analyzed by ion chromatography and liquid chromatographymass spectrometry. Furthermore, the results of the bacterial toxicity test indicated that the toxicity of the reaction solution decreased significantly after sonodegradation. This study provides a simple way for the rational design and successful preparation of S-scheme sonocatalyst with promising applications in the remediation of the water environment.

Automated summary

The development of efficient sonocatalysts is essential for treating antibiotic wastewater. In this study, an S-scheme sonocatalyst Cu2O/BiFeO3 was synthesized, where Cu2O nanoparticles were grown on the surface of BiFeO3. The Cu2O/BiFeO3 showed superior sonocatalytic performance for the degradation of tetracycline compared to pure BiFeO3. The improved performance can be attributed to the S-scheme charge transfer mechanism between Cu2O and BiFeO3, which inhibits electron-hole recombination and promotes carrier transfer.