Structural Study and Modification of Support Layer for Forward Osmosis Membranes

Handle URI:
http://hdl.handle.net/10754/617211
Title:
Structural Study and Modification of Support Layer for Forward Osmosis Membranes
Authors:
Shi, Meixia ( 0000-0002-4357-6873 )
Abstract:
Water scarcity is a serious global issue, due to the increasing population and developing economy, and membrane technology is an essential way to address this problem. Forward osmosis (FO) is an emerging membrane process, due to its low energy consumption (not considering the draw solute regeneration). A bottleneck to advance this technology is the design of the support layer for FO membranes to minimize the internal concentration polarization. In this dissertation, we focus on the structural study and modification of the support layer for FO membranes. Firstly, we digitally reconstruct different membrane morphologies in 3D and propose a method for predicting performance in ultrafiltration operations. Membranes with analogous morphologies are later used as substrate for FO membranes. Secondly, we experimentally apply substrates with different potentially suitable morphologies as an FO support layer. We investigate their FO performance after generating a selective polyamide layer on the top, by interfacial polymerization. Among the different substrates we include standard asymmetric porous membranes prepared from homopolymers, such as polysulfone. Additionally block copolymer membrane and Anodisc alumina membrane are chosen based on their exceptional structures, with cylindrical pores at least in part. 3D digitally reconstructed porous substrates, analogous to those investigated for ultrafiltration, are then used to model the performance in FO operation. Finally, we analyze the effect of intermediate layers between the porous substrate and the interfacial polymerized layer. We investigate two materials including chitosan and hydrogel. The main results are the following. Pore-scale modeling for digital membrane generation effectively predicts the velocity profile in different layers of the membrane and the performance in UF experiments. Flow simulations confirm the advantage of finger-like substrates over sponge-like ones, when high water permeance is sought. Cylindrical pores are advantageous for mass transfer. Block copolymer substrates have cylindrical pores in the top layer and very regular pore pattern at the surface. The Anodisc alumina membrane has cylindrical pores from top to bottom. Both substrates were experimentally tested for FO application successfully. A Darcy permeability higher than 1E-20 m2 for the intermediate layer would be necessary in order to facilitate the water flow.
Advisors:
Nunes, Suzana Pereira ( 0000-0002-3669-138X )
Committee Member:
Calo, Victor M. ( 0000-0002-1805-4045 ) ; Ng, Kim Choon ( 0000-0003-3930-4127 ) ; Sun, Shuyu ( 0000-0002-3078-864X ) ; Wang, Yan
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Environmental Science and Engineering
Issue Date:
Jun-2016
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorNunes, Suzana Pereiraen
dc.contributor.authorShi, Meixiaen
dc.date.accessioned2016-07-19T06:22:52Z-
dc.date.available2016-07-19T06:22:52Z-
dc.date.issued2016-06-
dc.identifier.urihttp://hdl.handle.net/10754/617211-
dc.description.abstractWater scarcity is a serious global issue, due to the increasing population and developing economy, and membrane technology is an essential way to address this problem. Forward osmosis (FO) is an emerging membrane process, due to its low energy consumption (not considering the draw solute regeneration). A bottleneck to advance this technology is the design of the support layer for FO membranes to minimize the internal concentration polarization. In this dissertation, we focus on the structural study and modification of the support layer for FO membranes. Firstly, we digitally reconstruct different membrane morphologies in 3D and propose a method for predicting performance in ultrafiltration operations. Membranes with analogous morphologies are later used as substrate for FO membranes. Secondly, we experimentally apply substrates with different potentially suitable morphologies as an FO support layer. We investigate their FO performance after generating a selective polyamide layer on the top, by interfacial polymerization. Among the different substrates we include standard asymmetric porous membranes prepared from homopolymers, such as polysulfone. Additionally block copolymer membrane and Anodisc alumina membrane are chosen based on their exceptional structures, with cylindrical pores at least in part. 3D digitally reconstructed porous substrates, analogous to those investigated for ultrafiltration, are then used to model the performance in FO operation. Finally, we analyze the effect of intermediate layers between the porous substrate and the interfacial polymerized layer. We investigate two materials including chitosan and hydrogel. The main results are the following. Pore-scale modeling for digital membrane generation effectively predicts the velocity profile in different layers of the membrane and the performance in UF experiments. Flow simulations confirm the advantage of finger-like substrates over sponge-like ones, when high water permeance is sought. Cylindrical pores are advantageous for mass transfer. Block copolymer substrates have cylindrical pores in the top layer and very regular pore pattern at the surface. The Anodisc alumina membrane has cylindrical pores from top to bottom. Both substrates were experimentally tested for FO application successfully. A Darcy permeability higher than 1E-20 m2 for the intermediate layer would be necessary in order to facilitate the water flow.en
dc.language.isoenen
dc.subjectMembraneen
dc.subjectMorphologyen
dc.subjectSimulationen
dc.subjectForward Osmosisen
dc.subjectSupport Layeren
dc.titleStructural Study and Modification of Support Layer for Forward Osmosis Membranesen
dc.typeDissertationen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberCalo, Victor M.en
dc.contributor.committeememberNg, Kim Choonen
dc.contributor.committeememberSun, Shuyuen
dc.contributor.committeememberWang, Yanen
thesis.degree.disciplineEnvironmental Science and Engineeringen
thesis.degree.nameDoctor of Philosophyen
dc.person.id113466en
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