Engineering mineralized interlayers for enhanced nanofiltration: Synergistic modulation of polyamide layer structure and catalytic self-cleaning performance

Abstract

High permselectivity and antifouling/self-cleaning nanofiltration (NF) membranes are ideal materials for water treatment, and this vision is expected to be reached through the design of multifunctional self-cleaning interfaces. In this study, we employed metal - polyphenol network (MPN) to mediate in situ mineralization of porous substrates, enabling simultaneous modulation of interfacial polymerization (IP) and catalytic self-cleaning. The findings demonstrate that the mineralized layers employ an interlayer modulation strategy to produce a polyamide (PA) layer that is more hydrophilic, thinner, and structurally denser. As a result, the resulting PA-Fe₃O₄-PSF membrane exhibited a 2.5-fold increase in permeance (19.2 L m⁻² h⁻¹ bar⁻¹) and a 7.3-fold enhancement in Cl⁻/SO₄²⁻ selectivity (66.4), compared to the control membrane (PA-PSF). Additionally, its highly polarized membrane surface significantly improved its antifouling performance. Compared to membranes with mineralized layers on the surface (Fe₃O₄-PA-PSF), PA-Fe₃O₄-PSF constructs a confined space that facilitates more efficient regeneration through in situ catalytic self-cleaning and ensures greater stability during multiple fouling-regeneration cycle operations. This study paves the way for fabricating multifunctional NF membranes with sustainable applications in material concentration, wastewater treatment, and environmental remediation.