Enhanced Water Permeability and Antifouling Property of Coffee-Ring-Textured Polyamide Membranes by In Situ Incorporation of a Zwitterionic Metal–Organic Framework

Abstract

Modulation of the polyamide structure is critically important for the reverse-osmosis performance of thin-film composite (TFC) membranes in the field of water reuse and desalination. Herein, zwitterionic nanoparticles of zeolitic imidazolate framework-8 (PZ@ZIF-8) were fabricated and incorporated into the polyamide active layer through the interfacial polymerization method. A hydrophilic, zwitterionic coffee-ring structure was formed on the surface of polyamide thin-film nanocomposite (TFN) membranes due to the adjusted diffusion rate of m-phenylenediamine (MPD) from the aqueous phase into the organic phase during the interfacial polymerization process. Surface characterization demonstrated that the coffee-ring structure increased the amounts of water transport channels on the membrane surface and the intrinsic pores of PZ@ZIF-8 maintained the salt rejection. Antifouling and bactericidal activities of TFN membranes were enhanced remarkably owing to the bacterial-"defending" and bacterial-"attacking" behaviors of hydrophilic and zwitterionic groups from PZ@ZIF-8 nanoparticles. This work would provide a promising method for the application of MOFs to enhance the bio-/organic-fouling resistance of TFN membranes with high water permeation and salt rejection.

Nanofiltration Membranes with Crumpled Polyamide Films: A Critical Review on Mechanisms, Performances, and Environmental Applications

“…Table S1 summarizes crumpled polyamide layers for PIP-based NF membranes reported in previous studies. Specifically, nodular, , stripe, ,, and ring ,− structures are the three most common morphologies (Figure ). Other structures, such as fishnetlike and octopus-sucker-like structures, are occasionally represented in some studies (Figure S1 provides the SEM images of some examples).…”

The coming of age of water channels for separation membranes: from biological to biomimetic to synthetic

“…Besides enhancing the membrane permeability, some fillers such as CNTs, MOFs and MXenes have also demonstrated success in decreasing fouling propensity, and enhancing boron This journal is © The Royal Society of Chemistry 2022 selectivity and chlorine resistance, all of which are crucial traits needed for RO membranes. 10,229,232,233 For some synthetic nanochannels like MXenes or CNTs, nanomaterials can be created as an interlayer between the support and polyamide layer (Fig. 16a and b).…”

“…Besides enhancing the membrane permeability, some fillers such as CNTs, MOFs and MXenes have also demonstrated success in decreasing fouling propensity, and enhancing boron selectivity and chlorine resistance, all of which are crucial traits needed for RO membranes. 10,229,232,233…”

Mechanistic Insights of a Thermoresponsive Interface for Fouling Control of Thin-Film Composite Nanofiltration Membranes

“…14−16 As a result, a hydrophilic membrane has a lower decline of flux and greater recovery of flux at the filtration and cleaning stages, respectively. To improve the hydrophilicity of the polyamide layer, hydrophilic materials were used via internal incorporation, 17 surface coating, 18 and grafting methods, 19 yielding various degrees of antifouling ability for the membrane. Nevertheless, with the continuous exposure of the polyamide layer to pollutants in the long-term membrane process, a hydrophilic membrane would also be inevitably covered by irreversible fouling, which cannot be cleaned via the traditional cleaning method.…”