On the presence of solute-solvent transport coupling in reverse osmosis

Roy, Yagnaseni; Lienhard, John H.

doi:10.1016/j.memsci.2020.118272

Cited by 8 publications

(14 citation statements)

References 34 publications

(85 reference statements)

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“…Transport Modeling. To study the underlying mechanisms that govern the selectivity of these membranes, we modeled the permeation of sodium salts using the MS equations (35)(36)(37). The MS equations, derived from irreversible thermodynamics, provide a comprehensive description of diffusion while also accounting for convection through frame of reference corrections and friction coupling (36,37).…”

Section: -mentioning

confidence: 99%

“…To study the underlying mechanisms that govern the selectivity of these membranes, we modeled the permeation of sodium salts using the MS equations (35)(36)(37). The MS equations, derived from irreversible thermodynamics, provide a comprehensive description of diffusion while also accounting for convection through frame of reference corrections and friction coupling (36,37). This framework has successfully modeled multicomponent diffusion in numerous membrane systems, including reverse osmosis, UF, ion exchange, pervaporation, and gas permeation membranes (35).…”

Section: -mentioning

confidence: 99%

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Interaction-based ion selectivity exhibited by self-assembled, cross-linked zwitterionic copolymer membranes

Lounder

Asatekin

2021

Proc. Natl. Acad. Sci. U.S.A.

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Water filtration membranes with advanced ion selectivity are urgently needed for resource recovery and the production of clean drinking water. This work investigates the separation capabilities of cross-linked zwitterionic copolymer membranes, a self-assembled membrane system featuring subnanometer zwitterionic nanochannels. We demonstrate that selective zwitterion–anion interactions simultaneously control salt partitioning and diffusivity, with the permeabilities of NaClO4, NaI, NaBr, NaCl, NaF, and Na2SO4 spanning roughly three orders of magnitude over a wide range of feed concentrations. We model salt flux using a one-dimensional transport model based on the Maxwell–Stefan equations and show that diffusion is the dominant mode of transport for 1:1 sodium salts. Differences in zwitterion–Cl− and zwitterion–F− interactions granted these membranes with the ultrahigh Cl−/F− permselectivity (PCl-/PF- = 24), enabling high fluoride retention and high chloride passage even from saline mixtures of NaCl and NaF.

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Section: -mentioning

confidence: 99%

Section: -mentioning

confidence: 99%

Interaction-based ion selectivity exhibited by self-assembled, cross-linked zwitterionic copolymer membranes

Lounder

Asatekin

2021

Proc. Natl. Acad. Sci. U.S.A.

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“…Permeabilities can be determined experimentally for reverse osmosis (RO) or, e.g., through simultaneously fitting A , B , and S [ 8 ]. In this study, the values of A [ 63 ] and B [ 64 ], measured by conventional methods, are considered as intrinsic membrane parameters. Cross-flow experiments on RO using deionized water DI water water at velocities ranging from 0.20–0.25 m/s and pressures ranging from 3–9 bar were conducted to determine the water permeability A, solute permeability B , and percentage of solute rejection R ( Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…Determining intrinsic membrane properties such as water ( A ) and salt permeability ( B ) is generally conducted through reverse osmosis (RO) experiments that independently vary hydraulic pressure, as illustrated in the literature [ 8 , 56 , 57 , 63 , 64 ]. The value of A is obtained from the gradient of water flux vs. the hydraulic pressure difference.…”

Section: Theoretical Developmentmentioning

confidence: 99%

The Need for Accurate Osmotic Pressure and Mass Transfer Resistances in Modeling Osmotically Driven Membrane Processes

et al. 2021

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The widely used van ’t Hoff linear relation for predicting the osmotic pressure of NaCl solutions may result in errors in the evaluation of key system parameters, which depend on osmotic pressure, in pressure-retarded osmosis and forward osmosis. In this paper, the linear van ’t Hoff approach is compared to the solutions using OLI Stream Analyzer, which gives the real osmotic pressure values. Various dilutions of NaCl solutions, including the lower solute concentrations typical of river water, are considered. Our results indicate that the disparity in the predicted osmotic pressure of the two considered methods can reach 30%, depending on the solute concentration, while that in the predicted power density can exceed over 50%. New experimental results are obtained for NanoH2O and Porifera membranes, and theoretical equations are also developed. Results show that discrepancies arise when using the van ’t Hoff equation, compared to the OLI method. At higher NaCl concentrations (C > 1.5 M), the deviation between the linear approach and the real values increases gradually, likely indicative of a larger error in van ’t Hoff predictions. The difference in structural parameter values predicted by the two evaluation methods is also significant; it can exceed the typical 50–70% range, depending on the operating conditions. We find that the external mass transfer coefficients should be considered in the evaluation of the structural parameter in order to avoid overestimating its value. Consequently, measured water flux and predicted structural parameter values from our own and literature measurements are recalculated with the OLI software to account for external mass transfer coefficients.

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“…The reader is referred to the articles by Wijmans and Baker [14], Roy and Lienhard [41] and Paul [42] for the differences with pore-flow and Maxwell-Stefan frameworks.…”

Section: Appendix a Derivation Of Solution-diffusion Equationsmentioning

confidence: 99%

Multicomponent Fickian solution-diffusion model for osmotic transport through membranes

Foo

Rehman

Coombs

et al. 2021

Journal of Membrane Science

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On the presence of solute-solvent transport coupling in reverse osmosis

Abstract: On the presence of solute-solvent transport coupling in reverse osmosis The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters.

Cited by 8 publications

References 34 publications

Interaction-based ion selectivity exhibited by self-assembled, cross-linked zwitterionic copolymer membranes

Interaction-based ion selectivity exhibited by self-assembled, cross-linked zwitterionic copolymer membranes

The Need for Accurate Osmotic Pressure and Mass Transfer Resistances in Modeling Osmotically Driven Membrane Processes

Multicomponent Fickian solution-diffusion model for osmotic transport through membranes

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