The role of interaction between low molecular weight neutral organic compounds and a polyamide RO membrane in the rejection mechanism

Zhang, Muxue; Breitner, Lauren; Howe, Kerry J.; Minakata, Daisuke

doi:10.1039/d0ra01966f

Cited by 10 publications

(7 citation statements)

References 43 publications

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“…Membrane transport of neutral organic solutes (i.e., nonelectrolytes) is influenced by physicochemical properties of the solute and membrane, and solute-membrane interactions (Dražević et al, 2017;Kim et al, 2007;Verliefde et al, 2009b;Zhang et al, 2020). Under the neutral condition (pH = 7) of the chlorine-alkaline treatment employed in this investigation, chlorine incorporation (N-and ring-chlorination) followed by polyamide degradation and chlorination-promoted hydrolysis are expected to be significant (Verbeke 2017).…”

Section: Figmentioning

confidence: 99%

“…Although the observed tradeoff trend in aqueous separation membranes fits within the general construct of the S-D model, fundamental understanding of the first principles governing the permeability and selectivity relationship of TFC-PA membranes is still lacking. Past studies looked at the rejection of contaminants, such as, endocrine disrupting compounds and disinfection byproducts, and made significant contributions to the understanding of transport in RO and NF membranes (Breitner et al, 2019;Comerton et al, 2008;Doederer et al, 2014;Kibler et al, 2020;Kim et al, 2007;Kimura et al, 2003;Kimura et al, 2004;Kong et al, 2015;Miyashita et al, 2009;Radjenović et al, 2008;Steinle-Darling et al, 2007;Williams et al, 1999;Xie et al, 2012;Yangali-Quintanilla et al, 2010;Yangali-Quintanilla et al, 2009;Yoon et al, 2007;Zhang et al, 2020). However, there is still no cohesive theoretical framework relating the transport phenomena to permeant and polymer properties.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Solute Molecular Diameter on Permeability-Selectivity Tradeoff of Thin-Film Composite Polyamide Membranes in Aqueous Separations

2021

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Fundamental understanding of the reverse osmosis (RO) transport phenomena is necessary for quantitative prediction of contaminant rejection and development of more selective membranes. The solution-diffusion (S-D) model predicts a tradeoff relationship between permeability and selectivity, and this tradeoff trend was recently reported for RO. But the first principles governing the relationship are not well understood for aqueous separation membranes. This study presents a framework to elucidate the underlying factors of the permeabilityselectivity tradeoff relationship in thin-film composite polyamide (TFC-PA) membranes. Water and solute permeabilities of membranes with a range of selectivities are examined using six nonelectrolyte solutes of various sizes and dimensions. The permeability-selectivity tradeoff trend, as defined by S-D, was observed for all six solutes. Crucially, the slopes of the tradeoff lines, λ, are found to be related to the solute and solvent (i.e., water) diameters, d s and d w , respectively, by λ = (d s /d w ) 2 -1, consistent with the S-D framework established for gas separation membranes. Additionally, the intercepts of the tradeoff lines are shown to be also influenced by d s . These results highlight that solute molecular diameter is a primary influence on the permeability-selectivity tradeoff for the permeants investigated in this study. Furthermore, a transport regime where solute permeation is only very weakly coupled to water transport, in addition to the conventional S-D, is identified for the first time. We demonstrate that the boundary delineating the two transport regimes can be determined by the solute diameter. The relationship between characteristic features of the "additional regime" and solute dimensions are analyzed. The study shows that the general principles of the S-D framework are applicable to TFC-PA membranes and the analysis quantified the principal role of solute size in governing RO transport. The experimental and analytical evidence suggest that nonelectrolyte solute transport can, in principle, be a priori predicted using molecular diameter. Findings of this investigation provide new insights for understanding the transport mechanisms in osmotic membrane processes.

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Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Solute Molecular Diameter on Permeability-Selectivity Tradeoff of Thin-Film Composite Polyamide Membranes in Aqueous Separations

2021

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“…Transport of neutral organic solutes across the membrane is influenced by physicochemical properties of the membrane selective layer and the solute molecules. ,− Specifically, solute partitioning into the membrane matrix is influenced by, among others, the permittivity and the hydrophilicity of the membrane matrix and the hydrogen bonding between the active layer and solute molecules. The chlorination-promoted hydrolysis in this study elevates the permittivity of the polyamide selective layer , and, thus, facilitates partitioning of the solute into the membrane from the bulk solution by lowering solvation energy barrier of the solutes. ,, The increased PA hydrophilicity by hydrolysis would enhance the solute-membrane affinity and enhance solute partitioning, as the octanol–water partition coefficients ≪1 for the two solutes in the study (i.e., Eg and Tr are hydrophilic). , Additionally, the two solute molecules possess multiple oxygen atoms, which can behave as hydrogen bond donors (hydroxyl groups in Eg) or acceptors (in Tr) and form H-bonds with the PA matrix.…”

Section: Resultsmentioning

confidence: 99%

Elucidating the Roles of Polyamide Layer Structural Properties in the Permeability–Selectivity Tradeoff Governing Aqueous Separations

et al. 2022

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A tradeoff relationship between permeability and selectivity of reverse osmosis and nanofiltration aqueous separation membranes is increasingly being documented. However, there is currently no comprehensive mechanistic framework to describe the roles of membrane structural properties in the transport tradeoff. This study investigates two key structural properties of the widely used thin-film composite polyamide (TFC-PA) membranes, namely, the free volume element (FVE) size and the effective transport pathway, and examines their influence on the tradeoff behavior. Permeability and selectivity performance were characterized by challenging chemically modified TFC-PA membranes with two neutral organic tracers. Positron annihilation lifetime spectroscopy (PALS) determined that the FVE diameters slightly increased for more permeable membranes, but the marginal size enlargement cannot fully account for the permeability trend. Instead, analysis using the hindered transport model showed that shortening of the effective transport pathway is identified as having a more significant effect on raising the water permeability. On the other hand, membrane selectivity is found to be dominated by FVE size and is essentially independent of the transport pathway. Lastly, a framework reconciling experimental evidence with transport theory is proposed to relate the influence of membrane structural properties on the permeability−selectivity tradeoff. Findings of this study provide fundamental insights for understanding the transport phenomena in aqueous separation membranes.

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“…Group Contribution Method. The mass transfer coefficient of a given organic through a membrane is a function of free energy of interaction according to our previous study using theoretical calculations 36 as below 37…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

“…The mass transfer coefficient of a given organic through a membrane is a function of free energy of interaction according to our previous study using theoretical calculations as below where a is the coefficient that relates the mass transfer coefficient with the interaction and molar volume, and Δ G solute–membrane intr is the overall free energy of interaction between a solute molecule and a membrane. Neutral organics do not experience a strong charge exclusion, and they may relatively easily partition and pass through the active layer.…”

Section: Materials and Methodsmentioning

confidence: 99%

Group Contribution Method to Predict the Mass Transfer Coefficients of Organics through Various RO Membranes

Kibler

Mohrhardt

Zhang

et al. 2020

Environ. Sci. Technol.

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Reverse osmosis (RO) is a membrane technology that separates dissolved species from water. RO has been applied for the removal of chemical contaminants from water for potable reuse applications. The presence of a wide variety of influent chemical contaminants and the insufficient rejection of low-molecular-weight neutral organics by RO calls for the need to develop a model that predicts the rejection of various organics. In this study, we develop a group contribution method (GCM) to predict the mass transfer coefficients by fragmenting the structure of low-molecular-weight neutral organics into small parts that interact with the RO membrane. Overall, 54 organics including 26 halogenated and oxygenated alkanes, 8 alkenes, and 20 alkyl and halobenzenes were used to determine 39 parameters to calibrate for 6 different RO membranes, including 4 brackish water and 2 seawater membranes. Through six membranes, approximately 80% of calculated rejection was within an error goal (i.e., ±5%) from the experimental observation. To extend the GCM for a reference RO membrane, ESPA2-LD, 14 additional organics were included from the literature to calibrate nitrogen-containing functional groups of nitrosamine, nitriles, and amide compounds. Overall, 49 organics (72% of 68 compounds) from calibration and 7 compounds (87.5% of 8 compounds) from prediction were within the error goal.

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The role of interaction between low molecular weight neutral organic compounds and a polyamide RO membrane in the rejection mechanism

Abstract: Reverse osmosis (RO) is a membrane technology that separates dissolved species from water.

Cited by 10 publications

References 43 publications

Influence of Solute Molecular Diameter on Permeability-Selectivity Tradeoff of Thin-Film Composite Polyamide Membranes in Aqueous Separations

Influence of Solute Molecular Diameter on Permeability-Selectivity Tradeoff of Thin-Film Composite Polyamide Membranes in Aqueous Separations

Elucidating the Roles of Polyamide Layer Structural Properties in the Permeability–Selectivity Tradeoff Governing Aqueous Separations

Group Contribution Method to Predict the Mass Transfer Coefficients of Organics through Various RO Membranes

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