Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

Handle URI:
http://hdl.handle.net/10754/561485
Title:
Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer
Authors:
Zhang, Sui; Wang, Kaiyu; Chung, Tai Shung Neal; Chen, Hongmin; Jean, Yanching; Amy, Gary L.
Abstract:
The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.
KAUST Department:
Water Desalination and Reuse Research Center (WDRC); Biological and Environmental Sciences and Engineering (BESE) Division
Publisher:
Elsevier BV
Journal:
Journal of Membrane Science
Issue Date:
Sep-2010
DOI:
10.1016/j.memsci.2010.05.056
Type:
Article
ISSN:
03767388
Sponsors:
The authors would like to thank EWI and NUS for funding this research project with a grant number of R-279-000-271-272 (MEWR 65 J106/158) and King Abdullah University of Science and Technology (KAUST) and NUS with a grant number of R-279-000-265-597. Thanks are also owing to Eastman Chemical Company for providing the cellulose acetate polymers. In particular, Miss Sui Zhang would like to thank Dr. Na Peng and Miss Huan Wang for their kindly suggestions.
Appears in Collections:
Articles; Water Desalination and Reuse Research Center (WDRC); Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorZhang, Suien
dc.contributor.authorWang, Kaiyuen
dc.contributor.authorChung, Tai Shung Nealen
dc.contributor.authorChen, Hongminen
dc.contributor.authorJean, Yanchingen
dc.contributor.authorAmy, Gary L.en
dc.date.accessioned2015-08-02T09:12:32Zen
dc.date.available2015-08-02T09:12:32Zen
dc.date.issued2010-09en
dc.identifier.issn03767388en
dc.identifier.doi10.1016/j.memsci.2010.05.056en
dc.identifier.urihttp://hdl.handle.net/10754/561485en
dc.description.abstractThe design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.en
dc.description.sponsorshipThe authors would like to thank EWI and NUS for funding this research project with a grant number of R-279-000-271-272 (MEWR 65 J106/158) and King Abdullah University of Science and Technology (KAUST) and NUS with a grant number of R-279-000-265-597. Thanks are also owing to Eastman Chemical Company for providing the cellulose acetate polymers. In particular, Miss Sui Zhang would like to thank Dr. Na Peng and Miss Huan Wang for their kindly suggestions.en
dc.publisherElsevier BVen
dc.subjectCellulose acetateen
dc.subjectForward osmosisen
dc.subjectMembranesen
dc.subjectPhase inversionen
dc.subjectPositron annihilation spectroscopyen
dc.titleWell-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layeren
dc.typeArticleen
dc.contributor.departmentWater Desalination and Reuse Research Center (WDRC)en
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.identifier.journalJournal of Membrane Scienceen
dc.contributor.institutionNUS Graduate School for Integrative Science and Engineering, National University of Singapore, Singapore 117576, Singaporeen
dc.contributor.institutionDepartment of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Singaporeen
dc.contributor.institutionDepartment of Chemistry, University of Missouri-Kansas City, Kansas City, Missouri 64110, Singaporeen
kaust.authorAmy, Gary L.en
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