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 Cu 2 O/BiFeO 3 has been fabricated using a simple synthesis method, in which Cu 2 O nanoparticles grow on the surface of BiFeO 3 . Tetracycline (TET) was selected as a representative pharmaceutical model to systematically evaluate the sonocatalytic performance of the Cu 2 O/BiFeO 3 . The experimental results showed that optimized Cu 2 O/BiFeO 3 (CBF-3) has superior sonocatalytic performance to TET (98.0 %, 0.02302 min −1 ), which is much higher than that of pure BiFeO 3 (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 Cu 2 O and BiFeO 3 , 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 chromatography-mass 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.