Electrochemical Removal of BSA Foulant Using a Stabilised Conductive PVDF Membrane Incorporated with Multiwall Carbon Nanotubes

Membrane fouling limits the sustainable application of polymeric membranes in wastewater treatment and water reuse. Strong adsorption of biomacromolecules and microorganisms can cause irreversible fouling, reducing membrane permeability and operational lifetime. This study developed conductive polyvinylidene fluoride (PVDF) membranes with multiwalled carbon nanotubes (hereafter referred to as CNTs) for electrochemically assisted removal of bovine serum albumin (BSA) foulants. A CNT-incorporated membrane (PVDF–CNT), prepared by phase inversion, and a CNT surface-coated membrane (CNT/PVDF), fabricated by vacuum filtration, were compared with pristine PVDF and a commercial hydrophilic PVDF membrane (c-PVDF). PVDF–CNT membrane exhibited an outstanding electrochemical response at approximately +1.6 V and the most pronounced signal variation after BSA addition. This enhanced response might be contributed by the combined contributions of β-phase-associated dipolar polarisation and interfacial polarisation at the CNT and PVDF interface, potentially promoting local charge accumulation and redistribution. After 3 min of electrochemical rinsing at +1.6 V in 0.2 mol/L Na₂SO₄ electrolyte, the PVDF–CNT membrane achieved a flux recovery ratio (FRR; the percentage of flux recovered after rinsing) of 67%, exceeding those of the pristine PVDF membrane (55%) and c-PVDF membrane (47%). Although the CNT/PVDF membrane exhibited a higher apparent FRR (91%), this behaviour was attributed to pore blockage by the deposited CNT layer and partial CNT detachment during rinsing, indicating limited structural stability. Across four consecutive fouling–rinsing cycles, the PVDF–CNT membrane showed smaller reductions in flux recovery (42.1%, 4.7%, and 23.8%) than c-PVDF (65.5%, 21.6%, and 25.5%). These findings highlighted the structural stability and electrochemical rinsing performance of the PVDF-CNT membrane and also suggested that tailoring the membrane’s combined polarisation-related behaviours offered a direction for improving electrochemically assisted foulant removal and flux recovery.