Solution-diffusion with defects model for pressure-assisted forward osmosis

Jintang Duan; Eric Litwiller; Ingo Pinnau

doi:10.1016/j.memsci.2014.07.018

Solution-diffusion with defects model for pressure-assisted forward osmosis

Jintang Duan, Eric Litwiller, Ingo Pinnau

Research output: Contribution to journal › Article › peer-review

44 Scopus citations

Abstract

An osmosis transport model is presented that combines the standard internal and external concentration polarization equations in the forward osmosis (FO) field with the selective layer transport equations first proposed by Sherwood in 1967. The Sherwood model describes water flux as the sum of a solute-selective, diffusive component driven by the sum of osmotic pressure and hydraulic pressure differences, and a nonselective, convective component driven by hydraulic pressure difference only. This solution-diffusion with defects (SDWD) model and the solution-diffusion (SD) model were compared against data collected using polyamide thin-film-composite (PA-TFC) and integrally-skinned asymmetric cellulose triacetate (CTA) membranes, evaluated in various configurations. When tested with pure water on the porous support side and 1.5. M (π=72.7. bar) sodium chloride solution on the selective layer side, applying 1.25. bar of hydraulic pressure to the porous support side increased water flux by an order of magnitude for PA-TFC membranes, but had negligible effect on CTA membrane flux. These large flux variations can be explained by the SDWD model, but not the SD model. To confirm the existence of defects, a PA-TFC membrane was coated with a uniform, highly water-permeable, nonselective polymer. After coating to block convection through defects, the influence of hydraulic pressure on water flux through this membrane essentially disappeared. Water flux through these defects is low (

Original language	English (US)
Pages (from-to)	323-333
Number of pages	11
Journal	Journal of Membrane Science
Volume	470
DOIs	https://doi.org/10.1016/j.memsci.2014.07.018
State	Published - Nov 2014

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Research reported in this publication was supported by King Abdullah University of Science and Technology (KAUST). The authors acknowledge HTI for providing FO membranes for this research. The authors also acknowledge Dr. Federico Pacheco for valuable discussions and Dr. Ali Behzad from KAUST Advanced Nanofabrication Imaging and Characterization Core Lab for assistance.

ASJC Scopus subject areas

Biochemistry
Filtration and Separation
General Materials Science
Physical and Theoretical Chemistry

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10.1016/j.memsci.2014.07.018

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title = "Solution-diffusion with defects model for pressure-assisted forward osmosis",

abstract = "An osmosis transport model is presented that combines the standard internal and external concentration polarization equations in the forward osmosis (FO) field with the selective layer transport equations first proposed by Sherwood in 1967. The Sherwood model describes water flux as the sum of a solute-selective, diffusive component driven by the sum of osmotic pressure and hydraulic pressure differences, and a nonselective, convective component driven by hydraulic pressure difference only. This solution-diffusion with defects (SDWD) model and the solution-diffusion (SD) model were compared against data collected using polyamide thin-film-composite (PA-TFC) and integrally-skinned asymmetric cellulose triacetate (CTA) membranes, evaluated in various configurations. When tested with pure water on the porous support side and 1.5. M (π=72.7. bar) sodium chloride solution on the selective layer side, applying 1.25. bar of hydraulic pressure to the porous support side increased water flux by an order of magnitude for PA-TFC membranes, but had negligible effect on CTA membrane flux. These large flux variations can be explained by the SDWD model, but not the SD model. To confirm the existence of defects, a PA-TFC membrane was coated with a uniform, highly water-permeable, nonselective polymer. After coating to block convection through defects, the influence of hydraulic pressure on water flux through this membrane essentially disappeared. Water flux through these defects is low (",

author = "Jintang Duan and Eric Litwiller and Ingo Pinnau",

note = "KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: Research reported in this publication was supported by King Abdullah University of Science and Technology (KAUST). The authors acknowledge HTI for providing FO membranes for this research. The authors also acknowledge Dr. Federico Pacheco for valuable discussions and Dr. Ali Behzad from KAUST Advanced Nanofabrication Imaging and Characterization Core Lab for assistance.",

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doi = "10.1016/j.memsci.2014.07.018",

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AU - Duan, Jintang

AU - Litwiller, Eric

AU - Pinnau, Ingo

N1 - KAUST Repository Item: Exported on 2020-10-01 Acknowledgements: Research reported in this publication was supported by King Abdullah University of Science and Technology (KAUST). The authors acknowledge HTI for providing FO membranes for this research. The authors also acknowledge Dr. Federico Pacheco for valuable discussions and Dr. Ali Behzad from KAUST Advanced Nanofabrication Imaging and Characterization Core Lab for assistance.

PY - 2014/11

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N2 - An osmosis transport model is presented that combines the standard internal and external concentration polarization equations in the forward osmosis (FO) field with the selective layer transport equations first proposed by Sherwood in 1967. The Sherwood model describes water flux as the sum of a solute-selective, diffusive component driven by the sum of osmotic pressure and hydraulic pressure differences, and a nonselective, convective component driven by hydraulic pressure difference only. This solution-diffusion with defects (SDWD) model and the solution-diffusion (SD) model were compared against data collected using polyamide thin-film-composite (PA-TFC) and integrally-skinned asymmetric cellulose triacetate (CTA) membranes, evaluated in various configurations. When tested with pure water on the porous support side and 1.5. M (π=72.7. bar) sodium chloride solution on the selective layer side, applying 1.25. bar of hydraulic pressure to the porous support side increased water flux by an order of magnitude for PA-TFC membranes, but had negligible effect on CTA membrane flux. These large flux variations can be explained by the SDWD model, but not the SD model. To confirm the existence of defects, a PA-TFC membrane was coated with a uniform, highly water-permeable, nonselective polymer. After coating to block convection through defects, the influence of hydraulic pressure on water flux through this membrane essentially disappeared. Water flux through these defects is low (

AB - An osmosis transport model is presented that combines the standard internal and external concentration polarization equations in the forward osmosis (FO) field with the selective layer transport equations first proposed by Sherwood in 1967. The Sherwood model describes water flux as the sum of a solute-selective, diffusive component driven by the sum of osmotic pressure and hydraulic pressure differences, and a nonselective, convective component driven by hydraulic pressure difference only. This solution-diffusion with defects (SDWD) model and the solution-diffusion (SD) model were compared against data collected using polyamide thin-film-composite (PA-TFC) and integrally-skinned asymmetric cellulose triacetate (CTA) membranes, evaluated in various configurations. When tested with pure water on the porous support side and 1.5. M (π=72.7. bar) sodium chloride solution on the selective layer side, applying 1.25. bar of hydraulic pressure to the porous support side increased water flux by an order of magnitude for PA-TFC membranes, but had negligible effect on CTA membrane flux. These large flux variations can be explained by the SDWD model, but not the SD model. To confirm the existence of defects, a PA-TFC membrane was coated with a uniform, highly water-permeable, nonselective polymer. After coating to block convection through defects, the influence of hydraulic pressure on water flux through this membrane essentially disappeared. Water flux through these defects is low (

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JO - Journal of Membrane Science

JF - Journal of Membrane Science

ER -

Solution-diffusion with defects model for pressure-assisted forward osmosis

Abstract

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