Piezoelectric Polyvinylidene Fluoride Membranes with Self-Powered and Electrified Antifouling Performance in Pressure-Driven Ultrafiltration Processes.

Abstract

Electroactive membranes have the potential to address membrane fouling via electrokinetic phenomena. However, additional energy consumption and complex material design represent chief barriers to achieving sustainable and economically viable antifouling performance. Herein, we present a novel strategy for fabricating a piezoelectric antifouling polyvinylidene fluoride (PVDF) membrane (Pi-UFM) by integrating the ion-dipole interactions (NaCl coagulation bath) and mild poling (in situ electric field) into a one-step phase separation process. This Pi-UFM with an intact porous structure could be self-powered in a typical ultrafiltration (UF) process via the responsivity to pressure stimuli, where the dominant β-PVDF phase and the out-of-plane aligned dipoles were demonstrated to be critical to obtain piezoelectricity. By challenging with different feed solutions, the Pi-UFM achieved enhanced antifouling capacity for organic foulants even with high ionic strength, suggesting that electrostatic repulsion and hydration repulsion were behind the antifouling mechanism. Furthermore, the TMP-dependent output performance of the Pi-UFM in both air and water confirmed its ability for converting ambient mechanical energy to in situ surface potential (ζ), demonstrating that this antifouling performance was a result of the membrane electromechanical transducer actions. Therefore, this study provides useful insight and strategy to enable piezoelectric materials for membrane filtration applications with energy efficiency and extend functionalities.