Tuning electrostatic repulsive and acid–base forces for efficient fouling mitigation in membrane filtration system

Abstract

Membrane fouling caused by colloidal particles and microorganisms impose restrictions to further practical implementation of membrane separation technology. To advance the practical applications of this technology sustainably, this study explores an in-situ fouling control strategy utilizing an electrochemical membrane filtration (EMF) system. By applying varying electric potentials, the study evaluated the impact on dissolved organic matter (DOM) removal and elucidated the fouling mechanisms involved. The results indicate that increasing the potential significantly enhances the water flux of the conductive carbon membrane (CC/PVDF), with the flux at 3.0 V being 2.1 times greater than at 0 V. Moreover, this adjustment in potential significantly reduces the attachment of viable bacteria to the CC/PVDF membrane, with an applied potential greater than or equal to 2 V completely inactivating Escherichia coli (E. coli). The cohesive free energy (ΔGSWS) and extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theories suggest that imposing an external potential improved the acid–base and electrostatic repulsive forces between foulants and the membrane, as the applied potentials significantly increased the surface potential and wettability of the membrane. This EMF system not only mitigates fouling effectively but also delineates a path for enhancing membrane durability in practical applications.