Effects of the support on the characteristics and permselectivity of thin film composite membranes

How the membrane support affects the performance of thin-film composite (TFC) membranes has long been under debate. Our present study experimentally establishes that the support pore number density (number per unit area) as well as its surface porosity play pivotal roles in affecting the characteris...

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Main Authors: Li, Xuesong, Li, Qing, Fang, Wangxi, Wang, Rong, Krantz, William B.
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/143849
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1438492021-02-10T08:52:26Z Effects of the support on the characteristics and permselectivity of thin film composite membranes Li, Xuesong Li, Qing Fang, Wangxi Wang, Rong Krantz, William B. School of Civil and Environmental Engineering Nanyang Environment and Water Research Institute Singapore Membrane Technology Centre Engineering::Environmental engineering Thin-film Composite Membrane Support How the membrane support affects the performance of thin-film composite (TFC) membranes has long been under debate. Our present study experimentally establishes that the support pore number density (number per unit area) as well as its surface porosity play pivotal roles in affecting the characteristics and permselectivity of TFC membranes. The structure of hollow fiber supports was finely tuned and characterized via a series of techniques, which provided a link to the physicochemical properties of the interfacially polymerized polyamide films. During the spinning process, decreasing the content of N-methyl-2-pyrrolidone in the bore fluid drastically reduced the pore size and surface porosity of the support. The resultant TFC membranes showed a lower water permeability (tested under 1 bar using 500 ppm NaCl). Adding lithium chloride to the polymer dope also led to a support with smaller pores and lower porosity, but increased surface pore number density. The resulting TFC membranes had a substantially higher water permeability and slightly higher salt rejection. In both arrays of membranes, all membranes shared similar thickness of polyamide leaf but a more crumpled film was found on a less porous support, suggesting that the surface porosity of the support affected the effective surface area of films. However, the TFC membrane with a higher effective surface area did not necessarily possess a higher permeability. Rather, a TFC membrane having a support with a higher surface porosity or a higher pore number density exhibited a higher water permeability, demonstrating that the lateral transport path of water through films had a significant impact on the water permeability of TFC membranes. Interestingly, in both cases, the selectivity of the TFC membranes was maintained when the water permeability increased. This study clarifies longstanding misunderstandings concerning the effects of the support on TFC membrane performance and provides insight into fabricating highly permeable and selective TFC membranes. Economic Development Board (EDB) Environment & Water Industry Development Council (EWI) National Research Foundation (NRF) Public Utilities Board (PUB) Accepted version This research is funded by Public Utilities Board, Singapore’s National Water Agency and a grant from the National Research Foundation of Singapore under its Environmental and Water Technologies Strategic Research Programme which is administered by the Environment and Water Industry (EWI) Programme Office of the PUB (1301-IRIS-44). The funding support from Singapore Economic Development Board to Singapore Membrane Technology Centre is also acknowledged. 2020-09-28T01:48:40Z 2020-09-28T01:48:40Z 2019 Journal Article Li, X., Li, Q., Fang, W., Wang, R., & Krantz, W. B. (2019). Effects of the support on the characteristics and permselectivity of thin film composite membranes. Journal of Membrane Science, 580, 12-23. doi:10.1016/j.memsci.2019.03.003 0376-7388 https://hdl.handle.net/10356/143849 10.1016/j.memsci.2019.03.003 580 12 23 en Journal of Membrane Science © 2019 Elsevier B.V. All rights reserved. This paper was published in Journal of Membrane Science and is made available with permission of Elsevier B.V. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Environmental engineering
Thin-film Composite Membrane
Support
spellingShingle Engineering::Environmental engineering
Thin-film Composite Membrane
Support
Li, Xuesong
Li, Qing
Fang, Wangxi
Wang, Rong
Krantz, William B.
Effects of the support on the characteristics and permselectivity of thin film composite membranes
description How the membrane support affects the performance of thin-film composite (TFC) membranes has long been under debate. Our present study experimentally establishes that the support pore number density (number per unit area) as well as its surface porosity play pivotal roles in affecting the characteristics and permselectivity of TFC membranes. The structure of hollow fiber supports was finely tuned and characterized via a series of techniques, which provided a link to the physicochemical properties of the interfacially polymerized polyamide films. During the spinning process, decreasing the content of N-methyl-2-pyrrolidone in the bore fluid drastically reduced the pore size and surface porosity of the support. The resultant TFC membranes showed a lower water permeability (tested under 1 bar using 500 ppm NaCl). Adding lithium chloride to the polymer dope also led to a support with smaller pores and lower porosity, but increased surface pore number density. The resulting TFC membranes had a substantially higher water permeability and slightly higher salt rejection. In both arrays of membranes, all membranes shared similar thickness of polyamide leaf but a more crumpled film was found on a less porous support, suggesting that the surface porosity of the support affected the effective surface area of films. However, the TFC membrane with a higher effective surface area did not necessarily possess a higher permeability. Rather, a TFC membrane having a support with a higher surface porosity or a higher pore number density exhibited a higher water permeability, demonstrating that the lateral transport path of water through films had a significant impact on the water permeability of TFC membranes. Interestingly, in both cases, the selectivity of the TFC membranes was maintained when the water permeability increased. This study clarifies longstanding misunderstandings concerning the effects of the support on TFC membrane performance and provides insight into fabricating highly permeable and selective TFC membranes.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Li, Xuesong
Li, Qing
Fang, Wangxi
Wang, Rong
Krantz, William B.
format Article
author Li, Xuesong
Li, Qing
Fang, Wangxi
Wang, Rong
Krantz, William B.
author_sort Li, Xuesong
title Effects of the support on the characteristics and permselectivity of thin film composite membranes
title_short Effects of the support on the characteristics and permselectivity of thin film composite membranes
title_full Effects of the support on the characteristics and permselectivity of thin film composite membranes
title_fullStr Effects of the support on the characteristics and permselectivity of thin film composite membranes
title_full_unstemmed Effects of the support on the characteristics and permselectivity of thin film composite membranes
title_sort effects of the support on the characteristics and permselectivity of thin film composite membranes
publishDate 2020
url https://hdl.handle.net/10356/143849
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