Electro-responsive OCNT/PPy membrane for efficient irreversible-fouling control through electroregulation of electrostatic and fluid interaction forces

Abstract

Membrane-based separation process has been proven to be a powerful strategy for low-energy-consumption and high-efficiency water purification. However, the practical application is still subjected to serious membrane fouling. In this study, an impressive approach to alleviate membrane fouling is proposed using an electro-conductive oxygenated carbon nanotube/polypyrrole (OCNT/PPy) membrane combining electrically-regulated electrostatic and fluid forces. Benefiting from the negative potential (−1.18 V vs. SCE) applied on the membrane, the electric polarization effects significantly enhance the repulsive electrostatic force on contaminant. The transmembrane pressure increases at an ignorable rate during the filtration process. Meanwhile, for accumulated irreversible membrane fouling after multi-cycle filtrations, the positive potential (+1.19 V vs. SCE) exerted on OCNT/PPy membrane can decrease the fluid resistances of backwash flow. As a result, the electrically-regulated hydraulic backwash achieves a thorough recovery rate of permeance at 99.1 %. The numerical analysis of the antifouling mechanism reveals that the mitigation of irreversible membrane fouling is mainly attributed to rapid formation of a loose cake layer under electrical assistance. Moreover, the computational fluid dynamics verifies that the reduction of water-channel resistance enhances the elimination of foulants in membrane pores. This work motivates a new thought for membrane fouling control through electroregulation of electrostatic and fluid forces at the membrane-water interface.