Preparation, characterization and performance of poly( m -phenylene isophthalamide)/organically modified montmorillonite nanocomposite membranes in removal of perfluorooctane sulfonate

Abstract

Nanocomposite membranes containing poly(m-phenylene isophthalamide) (PMIA) and organically modified montmorillonite (OMMT) were prepared by a combination of solution dispersion and wet-phase inversion methods, and the effects of OMMT addition on the properties and performance of fabricated nanofiltration membranes were investigated. The membranes were characterized by contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis, and zeta potential.The performance of the membranes was elucidated by the removal of perfluorooctane sulfonate (PFOS) at neutral pH. Increasing OMMT concentration improved the thermal stability and hydrophilicity of the membranes. The permeation and rejection of PFOS were significantly improved. The performance of fabricated nanofiltration membranes in removal of PFOS varied depending on the solute and membrane properties as well as solution conditions. Finally, a comparison between fabricated membranes and a commercial NF membrane (ESNA1-K1, Hydecanme) proved that the OMMT addition is a convenient procedure for producing nanocomposite membranes with superior properties and performance.

Evaluation of commercial nanofiltration and reverse osmosis membrane filtration to remove per‐and polyfluoroalkyl substances (PFAS): Effects of transmembrane pressures and water matrices

“…The electrostatic interactions can be enhanced by the increase of valence of the anions. For example, compared with the chloride (Cl − ) and sulfate (SO 4 2− ), phosphate (PO 4 3− ) showed the most significant effect on the membrane rejection of PFOS, where phosphate seems to enhance electronegativity of the NF membrane surface after adsorption and thus increase the PFOA rejection (Luo et al, 2016). For cations or metal ions, such as Mg 2+ , Ca 2+ , and Fe 3+ , their presence was shown to increase the rejection rates of PFOS on commercial NF membrane (ESNA1‐K1) membrane by 2%–3% (Zhao et al, 2018).…”

“…For cations or metal ions, such as Mg 2+ , Ca 2+ , and Fe 3+ , their presence was shown to increase the rejection rates of PFOS on commercial NF membrane (ESNA1-K1) membrane by 2%-3% (Zhao et al, 2018). Metal cations are believed to interact with the head functional groups of PFOS via electrostatic interactions, which increases the effective molecular size of PFAS and thus enables higher rejection by RO or NF (Luo et al, 2016). On the contrary, some studies reported that high NaCl concentrations (0.05-0.1 M) could induce a shielding effect on the negatively charged membrane and decrease the electrical double layer thickness, which reduces electrostatic repulsion between the membrane and PFAS and thus the rejection rate (Liu et al, 2022).…”

Advanced Polymeric Nanocomposite Membranes for Water and Wastewater Treatment: A Comprehensive Review

“…These membranes target emerging contaminants in the form of toxic molecules or ions in purified drinking water and wastewater. For example, several polymer nanocomposite studies have been conducted using different NPs such as silica NPs [ 367 ], nanoscale zero-valent iron [ 368 ], poly(piperazineamide) [ 369 ], selective polyamide layer [ 370 ], montmorillonite [ 371 ], nano-sized MoS 2 [ 372 ], GO [ 373 ], MWCNT [ 374 ], cellulose [ 324 ], etc., to achieve the efficient removal of PFAS, one of the proposed emerging contaminants by the US EPA. In addition to removing pollutants, the merits of integrating NPs in membrane filtration technologies includes the addition of structural and chemical properties such as chemical and thermal stability, antifouling, addition of surface charge, mechanical strength, enhanced hydrophilicity, porosity, tunable pore size and permeability, among others [ 215 , 375 , 376 ].…”

110th Anniversary: Selection of Cross-Linkers and Cross-Linking Procedures for the Fabrication of Solvent-Resistant Nanofiltration Membranes: A Review

“…Poly­(m-phenyleneisophthalamide) (PMIA) is an aromatic polyamide with great potentials for nanofiltration and OSN. − Zhu et al were the pioneers studying it with the incorporation of Mil-53­(Al) as mixed matrix membranes for OSN, while Hua et al designed the first PMIA composite membranes for OSN with the aid of HPEI and GA as cross-linkers . It was found that multiple-step cross-linking modifications (i.e., GA, HPEI, and then GA) were essential to form superior OSN membranes for use in solvents such as alcohols, hexane, and acetonitrile with reasonable rejections toward various dyes.…”