The increasing presence of emerging contaminants such as pharmaceuticals in water systems poses a significant environmental challenge due to their persistence and resistance to conventional treatment methods. Trimethoprim, a widely used antibiotic, is a frequent pollutant in wastewater and surface waters, raising concerns due to its bioactivity and toxicity. Advanced oxidation processes (AOPs), particularly photocatalysis, sonocatalysis, and their hybrid form sonophotocatalysis, offer promising strategies for degrading such contaminants through the generation of reactive oxygen species (ROS). Photocatalysis involves the use of a light-activated semiconductor catalyst that generates ROS under UV or visible light. Sonocatalysis relies on ultrasonic vibrations to excite piezoelectric materials and produce ROS. Bismuth tungstate (Bi₂WO₆), a layered Aurivillius oxide with a suitable bandgap (2.6 - 2.8 eV), exhibits enhanced photocatalytic performance due to its ability to promote charge carrier separation. WS₂, a two-dimensional transition metal dichalcogenide, offers strong piezocatalytic efficiency due to its mechanical flexibility, noncentrosymmetric monolayer structure, and highly polarizable W-S bonds, which improve charge separation under mechanical strain.

Integrating Bi₂WO₆ and WS₂ forms a heterojunction that enhances charge transfer and suppresses electron–hole recombination, synergistically boosting piezophotocatalytic performance. In this study, we developed a membrane system based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), incorporating a Bi₂WO₆@WS₂ powder heterojunction for the sonophotocatalytic degradation of trimethoprim antibiotic. The wt. % ratio of PVDF to Bi₂WO₆@7wt%WS₂ was equal to 70:30. The composite membranes were characterized using XRD, TEM, XPS, Raman, DRS UV-Vis, PL, EIS, Mott–Schottky, and photocurrent, revealing favorable structural, optical, and electrochemical properties.

The composite demonstrated high catalytic efficiency, reusability, and stability, effectively degrading trimethoprim in both distilled and river water. A possible degradation mechanism under combined light and ultrasonic treatment was proposed. This work presents a flexible membrane platform that combines piezo- and photocatalytic activity for advanced water treatment applications.