Robust polyamide-PTFE hollow fibre membranes for harsh organic solvent nanofiltration
Robust polyamide-PTFE hollow fibre membranes for harsh organic solvent nanofiltration
Polymeric membranes have been extensively studied for organic solvent nanofiltration (OSN) but many fail to show sufficient chemical resistance in strong solvents like dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This study focuses on harnessing the outstanding chemical resistance of polytetrafluoroethylene (PTFE), to develop polyamide-PTFE thin film composite (TFC) membranes that are resistant to such aprotic solvents. A defect-free polyamide thin film layer was successfully synthesized on the microfiltration PTFE hollow fibre substrates, overcoming challenges such as large and uneven pore size, and hydrophobicity of the PTFE substrates. A simple polydopamine (PDA) coating was carried out to improve the substrate's hydrophilicity prior to the polyamide synthesis via interfacial polymerization (IP). Polyethyleneimine (PEI) and trimesoyl chloride (TMC) were used as the monomers and a two-time IP method was employed to obtain a defect-free polyamide coating. The synthesized membranes showed high acetonitrile (ACN) and DMF permeabilities of 7.94 and 3.70 lm−2h−1bar−1, respectively, with acid fuchsin (585 Da) rejections of > 90 %. The molecular weight cut-off (MWCO) of the membranes could be further reduced to ∼300 Da by the addition of piperazine (PIP) monomers. The membranes also showed excellent stability and performance in a 72-hour OSN test performed in DMF indicating their great potential in effective molecular separation in harsh solvents. This study demonstrates how a simple modification and coating technique can transform commercially available microfiltration PTFE hollow fibres into durable and high value OSN membranes.
Hollow fibres, Interfacial polymerization, Organic solvent nanofiltration (OSN), Polyamide thin film, Polytetrafluoroethylene (PTFE)
Francis, Verona Nithya
bfc15508-e135-4ec9-92f6-eae2c94b3c68
Chong, Jeng Yi
2f9ead94-86f2-4e20-9e67-75f10759555b
Yang, Guoying
5f75a95a-9af9-486f-af6e-460c0e20c341
Che, Lei
ba029c07-b45e-4440-85d3-1347b6857042
Wang, Rong
fd4ca2d0-78f2-40c2-aad1-355e7f3f3022
24 September 2022
Francis, Verona Nithya
bfc15508-e135-4ec9-92f6-eae2c94b3c68
Chong, Jeng Yi
2f9ead94-86f2-4e20-9e67-75f10759555b
Yang, Guoying
5f75a95a-9af9-486f-af6e-460c0e20c341
Che, Lei
ba029c07-b45e-4440-85d3-1347b6857042
Wang, Rong
fd4ca2d0-78f2-40c2-aad1-355e7f3f3022
Francis, Verona Nithya, Chong, Jeng Yi, Yang, Guoying, Che, Lei and Wang, Rong
(2022)
Robust polyamide-PTFE hollow fibre membranes for harsh organic solvent nanofiltration.
Chemical Engineering Journal, 452 (Part 2), [139333].
(doi:10.1016/j.cej.2022.139333).
Abstract
Polymeric membranes have been extensively studied for organic solvent nanofiltration (OSN) but many fail to show sufficient chemical resistance in strong solvents like dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This study focuses on harnessing the outstanding chemical resistance of polytetrafluoroethylene (PTFE), to develop polyamide-PTFE thin film composite (TFC) membranes that are resistant to such aprotic solvents. A defect-free polyamide thin film layer was successfully synthesized on the microfiltration PTFE hollow fibre substrates, overcoming challenges such as large and uneven pore size, and hydrophobicity of the PTFE substrates. A simple polydopamine (PDA) coating was carried out to improve the substrate's hydrophilicity prior to the polyamide synthesis via interfacial polymerization (IP). Polyethyleneimine (PEI) and trimesoyl chloride (TMC) were used as the monomers and a two-time IP method was employed to obtain a defect-free polyamide coating. The synthesized membranes showed high acetonitrile (ACN) and DMF permeabilities of 7.94 and 3.70 lm−2h−1bar−1, respectively, with acid fuchsin (585 Da) rejections of > 90 %. The molecular weight cut-off (MWCO) of the membranes could be further reduced to ∼300 Da by the addition of piperazine (PIP) monomers. The membranes also showed excellent stability and performance in a 72-hour OSN test performed in DMF indicating their great potential in effective molecular separation in harsh solvents. This study demonstrates how a simple modification and coating technique can transform commercially available microfiltration PTFE hollow fibres into durable and high value OSN membranes.
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More information
Accepted/In Press date: 16 September 2022
e-pub ahead of print date: 21 September 2022
Published date: 24 September 2022
Additional Information:
Funding Information:
The authors would like to acknowledge the funding support from the Singapore Economic Development Board to the Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute (NEWRI) at Nanyang Technological University (NTU), Singapore. We would like to acknowledge Ms. Mei Shan Lam from the NEWRI Analytics Cluster for the XPS characterisation. Guoying Yang and Lei Che would like to acknowledge the support from Leading Innovation and Entrepreneurship Team in Zhejiang Province, PR China (2019R01008). Verona Nithya Francis would also like to acknowledge NTU for providing the scholarship for her master’s studies.
Keywords:
Hollow fibres, Interfacial polymerization, Organic solvent nanofiltration (OSN), Polyamide thin film, Polytetrafluoroethylene (PTFE)
Identifiers
Local EPrints ID: 486394
URI: http://eprints.soton.ac.uk/id/eprint/486394
ISSN: 1385-8947
PURE UUID: 178707d5-687c-4467-8077-e13014d926ad
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Date deposited: 19 Jan 2024 17:32
Last modified: 02 Aug 2024 02:04
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Author:
Verona Nithya Francis
Author:
Jeng Yi Chong
Author:
Guoying Yang
Author:
Lei Che
Author:
Rong Wang
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