Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process

Development of alternative water sources through seawater desalination by applying osmotic pressure-driven forward osmosis (FO) technologies has become one of the most reliable approaches to overcome the global water scarcity. In this study, as to achieve lower internal concentration polarization (I...

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Main Author:	Arsat, Nurafidah
Format:	Thesis
Language:	English
Published:	2020
Subjects:	Q Science (General) TP Chemical technology
Online Access:	http://eprints.utm.my/id/eprint/101508/1/NurafidahArsatMSChE2020.pdf
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spelling	my-utm-ep.1015082023-06-26T01:50:09Z Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process 2020 Arsat, Nurafidah Q Science (General) TP Chemical technology Development of alternative water sources through seawater desalination by applying osmotic pressure-driven forward osmosis (FO) technologies has become one of the most reliable approaches to overcome the global water scarcity. In this study, as to achieve lower internal concentration polarization (ICP), nanofiber membrane with highly porous, thin and has low tortuosity was used as the substrate for FO membrane. Additionally, to minimize the penetration issue arising from conventional method of fabricating selective layer in which the casting solutions penetrated into the scaffold structure of nanofibrous substrates, this current work utilized the dual-layered nanofibrous mats and cross-link technique to fabricate polyvinyl alcohol (PVA) selective layer. PVA was chosen because it is highly hydrophilic and possesses good film-forming properties. The main objective of this research is to fabricate polyvinylidene fluoride (PVDF) nanofiber-supported PVA thin film nanofibrous composite (TFNC) membrane for FO process. Meanwhile, the sub-objectives are to investigate the effects of PVA loadings and to evaluate the performances of the resultant composite membranes in terms of intrinsic separation properties, FO testing and ICP comparison with asymmetric structure-supported composite membrane prepared via phase inversion technique. The experiment began with the fabrication of PVDF nanofibrous substrate via electrospinning. Subsequently, the selective layer of PVA nanofibers was prepared via electrospinning at different PVA loadings (2, 4, 6, 8, 9 and 10% w/v), prior to PVA cross-linking process. The characterizations of the substrate and PVA/PVDF composite membranes were done using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, contact angle measurement and mercury intrusion porosimetry (MIP). Finally, the resulting TFNC membranes were evaluated in terms of intrinsic separation properties and FO performances, followed by the ICP evaluation comparison between the chosen nanofiber-supported TFNC membranes and asymmetric structure-supported TFC membranes. It was found that the best loading of PVA was 8% w/v (denoted as PVA 8/PVDF) as it possessed the highest water permeability (1.33 L/m².h.bar) with 43.35% salt rejection and a ratio of 6.20 kPA between water and salt permeabilities. Also, PVA 8/PVDF composite membranes showed considerable performances in FO process with water flux of 4.83 LMH, reverse solute flux of 0.0242 gMH and significantly low specific reverse solute flux of 0.005 g/L. Besides, ICP effect in nanofiber-supported TFNC membrane was reduced by 30% as compared with asymmetric structure-supported TFC membrane. Therefore, this study may lead to a new strategy of developing dual-layered TFNC membrane via PVA cross-linking technique which could provide a good solution to solve the penetration issue, apart from mitigating the ICP bottleneck. 2020 Thesis http://eprints.utm.my/id/eprint/101508/ http://eprints.utm.my/id/eprint/101508/1/NurafidahArsatMSChE2020.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:149053 masters Universiti Teknologi Malaysia, Faculty of Engineering - School of Chemical & Energy Engineering Faculty of Engineering - School of Chemical & Energy Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	Q Science (General) TP Chemical technology
spellingShingle	Q Science (General) TP Chemical technology Arsat, Nurafidah Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
description	Development of alternative water sources through seawater desalination by applying osmotic pressure-driven forward osmosis (FO) technologies has become one of the most reliable approaches to overcome the global water scarcity. In this study, as to achieve lower internal concentration polarization (ICP), nanofiber membrane with highly porous, thin and has low tortuosity was used as the substrate for FO membrane. Additionally, to minimize the penetration issue arising from conventional method of fabricating selective layer in which the casting solutions penetrated into the scaffold structure of nanofibrous substrates, this current work utilized the dual-layered nanofibrous mats and cross-link technique to fabricate polyvinyl alcohol (PVA) selective layer. PVA was chosen because it is highly hydrophilic and possesses good film-forming properties. The main objective of this research is to fabricate polyvinylidene fluoride (PVDF) nanofiber-supported PVA thin film nanofibrous composite (TFNC) membrane for FO process. Meanwhile, the sub-objectives are to investigate the effects of PVA loadings and to evaluate the performances of the resultant composite membranes in terms of intrinsic separation properties, FO testing and ICP comparison with asymmetric structure-supported composite membrane prepared via phase inversion technique. The experiment began with the fabrication of PVDF nanofibrous substrate via electrospinning. Subsequently, the selective layer of PVA nanofibers was prepared via electrospinning at different PVA loadings (2, 4, 6, 8, 9 and 10% w/v), prior to PVA cross-linking process. The characterizations of the substrate and PVA/PVDF composite membranes were done using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, contact angle measurement and mercury intrusion porosimetry (MIP). Finally, the resulting TFNC membranes were evaluated in terms of intrinsic separation properties and FO performances, followed by the ICP evaluation comparison between the chosen nanofiber-supported TFNC membranes and asymmetric structure-supported TFC membranes. It was found that the best loading of PVA was 8% w/v (denoted as PVA 8/PVDF) as it possessed the highest water permeability (1.33 L/m².h.bar) with 43.35% salt rejection and a ratio of 6.20 kPA between water and salt permeabilities. Also, PVA 8/PVDF composite membranes showed considerable performances in FO process with water flux of 4.83 LMH, reverse solute flux of 0.0242 gMH and significantly low specific reverse solute flux of 0.005 g/L. Besides, ICP effect in nanofiber-supported TFNC membrane was reduced by 30% as compared with asymmetric structure-supported TFC membrane. Therefore, this study may lead to a new strategy of developing dual-layered TFNC membrane via PVA cross-linking technique which could provide a good solution to solve the penetration issue, apart from mitigating the ICP bottleneck.
format	Thesis
qualification_level	Master's degree
author	Arsat, Nurafidah
author_facet	Arsat, Nurafidah
author_sort	Arsat, Nurafidah
title	Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
title_short	Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
title_full	Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
title_fullStr	Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
title_full_unstemmed	Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
title_sort	polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process
granting_institution	Universiti Teknologi Malaysia, Faculty of Engineering - School of Chemical & Energy Engineering
granting_department	Faculty of Engineering - School of Chemical & Energy Engineering
publishDate	2020
url	http://eprints.utm.my/id/eprint/101508/1/NurafidahArsatMSChE2020.pdf
_version_	1776100714672553984

Polyvinylidene fluoride nanofiber-supported polyvinyl alcohol thin film nanofibrous composite membrane for forward osmosis process

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