From Heterojunction Design to Real-Water Performance: Bi₂WO₆@WS₂-PVDF-HFP Sonophotocatalytic Membranes

The persistence of pharmaceutical contaminants in aquatic environments, coupled with their inefficient removal by conventional treatment technologies, poses escalating risks to ecosystems and public health. Herein, we report the development of a hybrid Bi₂WO₆@WS₂-PVDF-HFP composite membrane as an efficient and reusable platform for the sonophotocatalytic degradation of the antibiotic trimethoprim (TMP). The membrane integrates a type-II Bi₂WO₆@WS₂ heterojunction within a piezoelectric PVDF-HFP matrix, enabling synergistic coupling between photocatalytic and sonocatalytic processes.

Comprehensive structural, optical, and electrochemical characterizations confirm strong interfacial coupling, broadened visible-light absorption, enhanced charge separation, and reduced recombination. Under combined light irradiation and ultrasound, the hybrid membrane achieves complete TMP degradation, outperforming membranes containing individual components. Kinetic analyses indicate predominantly pseudo-second-order behavior, while adsorption isotherms suggest favorable, mainly monolayer-type interactions between TMP and the catalytic surface.

Importantly, the membrane maintains high degradation efficiency in complex matrices, including surface water and groundwater, demonstrating robustness beyond model solutions. Reusability tests show 100% degradation efficiency over three consecutive cycles, highlighting excellent structural and functional stability. Liquid chromatography–mass spectrometry analyses indicate that hybrid sonophotocatalysis promotes extensive degradation of trimethoprim, preventing the accumulation of persistent and toxic transformation products.

Overall, this work demonstrates a scalable and environmentally friendly membrane-based strategy that combines photoactivity, piezoelectricity, and material stability, offering a promising solution for the remediation of emerging pharmaceutical contaminants in real water systems.