Tailoring polyamide membranes via dynamic interfacial manipulation with functional Fe3O4 nanoparticles for elevated Nanofiltration performance

This study investigates the enhancement of thin-film-composite polyamide (TFC-PA) membranes for nanofiltration (NF) by conducting direct interfacial polymerization (IP) at a substrate-free water/n-hexane interface. Fe 3 O 4 nanoparticles , stabilized with surfactants sodium laurate (SL) and hexadecyltrimethylammonium bromide (CTAB), were employed to dynamically influence the diffusion of piperazine (PIP) monomers . The incorporation of these nanoparticles enabled the modulation of the IP process, yielding membranes with distinct morphologies and performance characteristics. Specifically, membranes with SL-stabilized Fe 3 O 4 (SLF) demonstrated enhanced cross-linking and superior salt rejection capabilities for divalent cations, with MgCl 2 and CaCl 2 rejection rates notably increasing to 95.5 % and 93.4 % respectively. Conversely, CTAB-stabilized Fe 3 O 4 (CTABF) membranes, characterized by smoother surfaces and a looser structure, exhibited increases in water permeance up to 140 % relative to controls, but with a significant reduction in salt rejection efficacy as nanoparticle concentration increased. This study highlights the crucial impact of surfactant-stabilized nanoparticle modifications in manipulating the IP process and tailoring the filtration properties of PA membranes, offering promising avenues for optimizing NF membrane technology .