Poly(vinylidene fluoride) Substrate-Supported Polyamide Membrane for High-Temperature Water Nanofiltration

Abstract

Conventional polysulfone and polyethersulfone membrane-supported polyamide (PA) nanofiltration (NF) membranes suffer an obvious performance decline due to the drastic pore shrinkage of their membranes during high-temperature (HT) desalination processes. Herein, a thermally stable PA NF membrane (PVDF-IP-2) was successfully constructed over a relatively hydrophobic polyvinylidene fluoride (PVDF) membrane using a continuous interfacial polymerization (CIP) method. The PVDF-IP-2 membrane had a moderate water permeance of 8.3 L m–2 h–1 bar–1 and a 99.7% Na2SO4 rejection at room temperature, which were comparable to those of commercial NF membranes. Introducing calcium ions (Ca2+) into the aqueous solutions further confined the transport rate of the piperazine monomer across the reaction interface through the coordination functions between Ca2+ and piperazine molecules, forming a high-flux (15.9 L m–2 h–1 bar–1 at room temperature) NF membrane (PVDF-IP-Ca) with an excellent Na2SO4 rejection (∼98.6%). Impressively, the PVDF-IP-Ca membrane presented an excellent antifouling behavior and performance stability during both fouling and high-temperature filtration tests. The Ca2+-assisted IP (Ca–CIP) strategy is expected to be a facile and universal approach to preparing TFC desalination membranes for HT environmental applications on relatively hydrophobic supports.

Dendritic Mesoporous Silica Nanosphere-Embedded Polyacrylonitrile Electrospun Composite Nanofiltration Membrane with Crumpled Structure and High Water Permeance

“…As the hydrolyzed PAN electrospun membrane has substantial −COOH groups, and the surface of DMSNs has a large number of −OH groups, we speculate that the zeta potentials of PAN−PA and PAN− DMSNs−PA composite NF membranes are also influenced by a PAN electrospun fiber and embedded DMSNs. 13,19,22 Therefore, DMSN embedding could lower the zeta potential 6d). The pore size of the PA layer is mainly determined by its cross-linking degree.…”

Interface Engineering of Microporous Polypropylene Membranes for Polyamide Thin-Film Composite Nanofiltration Membranes with Robust Structure and Superior Performance

“…It should be noted that the property of the PA separation layer is greatly influenced by the physicochemical properties of the substrates . Typically, the substrates of the commercial TFC membranes are mostly polysulfone (PSF) or polyethersulfone (PES) membranes . A uniform interfacial polymerization reaction can be conducted on these membranes due to their desirable hydrophilicity which is conducive to uniformly distributing the aqueous solution of diamine monomers on their surfaces.…”

“…13 Typically, the substrates of the commercial TFC membranes are mostly polysulfone (PSF) or polyethersulfone (PES) membranes. 14 A uniform interfacial polymerization reaction can be conducted on these membranes due to their desirable hydrophilicity which is conducive to uniformly distributing the aqueous solution of diamine monomers on their surfaces. However, these substrates exhibit relatively weak mechanical strength and low chemical resistance to organic solvents such as N,N-dimethylformamide and acetone, limiting their application in severe operating conditions.…”

Surface Modification of Nanofiltration Membranes by Interpenetrating Polymer Networks and Their Evaluation in Water Desalination

“…Nanofiltration (NF) technology has wide applications in different industrial sectors, such as seawater treatment, wastewater, pharmaceutical processes, and the food industry . With properties between ultrafiltration (UF) and reverse osmosis (RO), NF membranes generate high water permeate flux, high divalent ion rejection compared to lower monovalent salts, low-energy requirement, and low initial capital investment , compared to RO. The increasing technological development in the manufacture of polyamide (PA) thin-film composite (TFC) membranes has dominated the NF separation technology, increasing its separation efficiency, chlorine resistance, improved ionic separation, hydrophobicity, and surface charge, among others. , Although TFC membranes have performed good responses to different industrial applications, there is still interest in improving membrane properties, such as the rejection of monovalent species, without sacrificing the separation efficiency of NF membranes and high permeability. , …”

“…The increasing technological development in the manufacture of polyamide (PA) thin-film composite (TFC) membranes has dominated the NF separation technology, increasing its separation efficiency, chlorine resistance, improved ionic separation, hydrophobicity, and surface charge, among others. 2,5 Although TFC membranes have performed good responses to different industrial applications, there is still interest in improving membrane properties, such as the rejection of monovalent species, without sacrificing the separation efficiency of NF membranes and high permeability. 4,6 Several methods have been employed to improve the permeability and selectivity of TFC membranes.…”