Construction of Ag₂WO₄/CuBi₂O₄ S-Scheme Heterojunctions with Enhanced Sonocatalytic Performance for the Removal of Tetracycline: Characterization, Sonocatalytic Mechanism, and Degradation Pathways

This study successfully synthesized Ag₂WO₄/CuBi₂O₄ (ACBO) composite materials via a two-step method. Tetracycline (TET) was employed as a model pollutant to evaluate the sonocatalytic performance of Ag₂WO₄/CuBi₂O₄ composite materials. Among all samples, ACBO-30 exhibited the most outstanding sonocatalytic activity. Under optimal experimental conditions, the removal efficiency of TET reached 98.06 ± 1.10%. Based on the results of active species trapping experiments and X-ray photoelectron spectroscopy, it was confirmed that an S-scheme heterojunction formed between Ag₂WO₄ and CuBi₂O₄, which effectively promoted the separation of electron-hole pairs and significantly enhanced the sonocatalytic performance of CuBi₂O₄. Cyclic experiments further demonstrated that the Ag₂WO₄/CuBi₂O₄ composite catalyst possessed excellent reusability and stability. Through high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, several plausible conversion pathways of the TET were proposed. Biological toxicity tests verified that the sonocatalytic technology could degrade TET into less toxic byproducts. This study provides valuable insights into the design and development of novel sonocatalysts for the efficient treatment of pharmaceutical wastewater.