Novel conductive membranes breaking through the selectivity-permeability trade-off for Congo red removal

The permeability-selectivity trade-off remains the major drawback limiting application of membrane technology. This study provided a new strategy to break through this trade-off. A novel conductive membrane prepared by electroless Ni plating of the polyvinylidene fluoride (PVDF) membrane was used for dyeing wastewater treatment by applying an electric field. Series analyses demonstrated success of immobilizing a Ni/NiO layer on the pristine PVDF membrane. The conductive membrane possessed improved hydrophilicity indicated by the water contact angle decrease from 75.5 degrees to 45.0 degrees. Moreover, the conductive PVDF membrane integrating electric field voltage of 20 V simultaneously possessed high selectivity (97.93% rejection) and extremely high permeability (202.51 +/- 9.63 Lm(-2) h(-1) at 0.1 MPa) for filtration of Congo red (CR) solution, significantly breaking through the permeability-selectivity trade-off. The filtration performance was quite stable even after 6 filtration cycles, indicating the feasibility of the conductive membrane for long-term treatment of CR wastewater. In addition, the conductive membrane showed high antifouling ability to methylene blue (MB), rhodamine B (RB), CR and microorganisms. The conductive membranes, together with the new strategy, offered indepth insights into membrane fabrication.