Fundamentals of Membrane Transport Phenomena

doi:10.1002/9781118932551.ch6

Cited by 2 publications

(1 citation statement)

References 44 publications

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“…The solution-diffusion model (SD) assumes that a chemical species from the feed stream dissolves in the membrane selective layer and is transported across it by diffusion, with desorption occurring at the membrane/permeate interface. This model considers that the pressure inside the membrane is uniform, so the chemical potential gradient of the chemical species permeating the membrane is represented just as a concentration gradient [ 49 ]. In fact, the SD model is already thoroughly detailed in the literature [ 50 ] and has been applied by other authors to different PhACs in forward osmosis (FO), RO, and NF membranes [ 51 , 52 , 53 ].…”

Section: Theorymentioning

confidence: 99%

Ultrafiltration and Nanofiltration for the Removal of Pharmaceutically Active Compounds from Water: The Effect of Operating Pressure on Electrostatic Solute—Membrane Interactions

Giacobbo,

Pasqualotto,

Machado Filho

et al. 2023

Membranes

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The present work investigates nanofiltration (NF) and ultrafiltration (UF) for the removal of three widely used pharmaceutically active compounds (PhACs), namely atenolol, sulfamethoxazole, and rosuvastatin. Four membranes, two polyamide NF membranes (NF90 and NF270) and two polyethersulfone UF membranes (XT and ST), were evaluated in terms of productivity (permeate flux) and selectivity (rejection of PhACs) at pressures from 2 to 8 bar. Although the UF membranes have a much higher molecular weight cut-off (1000 and 10,000 Da), when compared to the molecular weight of the PhACs (253–482 Da), moderate rejections were observed. For UF, rejections were dependent on the molecular weight and charge of the PhACs, membrane molecular weight cut-off (MWCO), and operating pressure, demonstrating that electrostatic interactions play an important role in the removal of PhACs, especially at low operating pressures. On the other hand, both NF membranes displayed high rejections for all PhACs studied (75–98%). Hence, considering the optimal operating conditions, the NF270 membrane (MWCO = 400 Da) presented the best performance, achieving permeate fluxes of about 100 kg h−1 m−2 and rejections above 80% at a pressure of 8 bar, that is, a productivity of about twice that of the NF90 membrane (MWCO = 200 Da). Therefore, NF270 was the most suitable membrane for this application, although the tight UF membranes under low operating pressures displayed satisfactory results.

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Section: Theorymentioning

confidence: 99%

Ultrafiltration and Nanofiltration for the Removal of Pharmaceutically Active Compounds from Water: The Effect of Operating Pressure on Electrostatic Solute—Membrane Interactions

Giacobbo,

Pasqualotto,

Machado Filho

et al. 2023

Membranes

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2D Covalent Organic Framework Membranes for Liquid‐Phase Molecular Separations: State of the Field, Common Pitfalls, and Future Opportunities

et al. 2023

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Two‐dimensional covalent organic frameworks (2D COFs) are attractive candidates for next‐generation membrane active layers due to their robust linkages and uniform, tunable pores. Many publications have claimed to achieve selective molecular transport through 2D COF membranes, but reported performance metrics for similar networks vary dramatically, and in several cases the reported experiments are inadequate to support such conclusions. These issues require a reevaluation of the literature. Published examples of 2D COF membranes for liquid‐phase separations can be broadly divided into two categories, each with common performance characteristics: polycrystalline COF films (most >1 μm thick) and weakly crystalline or amorphous films (most <500 nm thick). The former exhibit high solvent permeance, and most, if not all, function as selective adsorbents rather than membranes. The latter behave as membranes with lower permeance in line with conventional reverse osmosis and nanofiltration membranes but have amorphous or ambiguous long‐range order that precludes conclusions about separations occurring via selective transport through the COF pores. So far, neither category has demonstrated consistent relationships between the designed COF pore structure and separation performance, suggesting that these imperfect materials do not sieve molecules through uniform pores. In this perspective, we describe rigorous characterization practices that should be applied to both COF membrane structure and separation performance, which will facilitate their development toward molecularly precise membranes capable of performing previously unrealized chemical separations. In the absence of this more rigorous standard of proof, reports of COF‐based membranes should be treated with skepticism. As methods to control 2D polymerization and 2D polymer processing improve, we anticipate that precise 2D polymer membranes will exhibit exquisite and energy efficient performance relevant for contemporary separation challenges.This article is protected by copyright. All rights reserved

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Fundamentals of Membrane Transport Phenomena

Cited by 2 publications

References 44 publications

Ultrafiltration and Nanofiltration for the Removal of Pharmaceutically Active Compounds from Water: The Effect of Operating Pressure on Electrostatic Solute—Membrane Interactions

Ultrafiltration and Nanofiltration for the Removal of Pharmaceutically Active Compounds from Water: The Effect of Operating Pressure on Electrostatic Solute—Membrane Interactions

2D Covalent Organic Framework Membranes for Liquid‐Phase Molecular Separations: State of the Field, Common Pitfalls, and Future Opportunities

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