Conductive nanofiltration membrane with a hydrogel coated stainless steel mesh support for electrically enhanced fouling mitigation potential

Abstract

The performance of nanofiltration (NF) membranes will inevitably be compromised by membrane fouling in real practice. Electro-conductive NF membranes with the assistance of an external electric field have strong prospects in membrane fouling mitigation. In this study, we developed a facile approach to synthesize a conductive thin-film composite (TFC) NF membrane. Kevlar hydrogel was first pre-coated on a stainless steel mesh (SSM) for the formation of a conductive composite support (SMM-K) through phase inversion. The hydrogel medium enabled adequate amine monomer storage and thereby a homogeneous interfacial polymerization (IP) reaction, producing a dense and continuous polyamide (PA) active layer. The synthesized SSM-K-PA NF membrane showed an ∼70% increase of water permeance compared to the NF270 membrane while maintaining an ideal SO₄²⁻/Cl⁻ selectivity (95.3 ± 1.0% for Na₂SO₄ rejection and 15.5 ± 1.8% for NaCl). The attachment of the hydrogel and the deposition of the PA layer did not significantly affect the electrochemical properties of the SSM. The SSM-K-PA NF membrane acted as the cathode in an electrically-assisted NF system and showed an antifouling performance against wastewater containing bovine serum albumin (BSA) when an external electric field was applied in situ. This work paves a new way to fabricate conductive TFC NF membranes with favorable NF performance and electro-assisted fouling mitigation potential.