Improving nanofiber membrane characteristics and membrane distillation performance of heat-pressed membranes via annealing post-treatment

Yao, M; Woo, YC; Tijing, LD; Cesarini, C; Shon, HK

Improving nanofiber membrane characteristics and membrane distillation performance of heat-pressed membranes via annealing post-treatment

Yao, M Woo, YC

Tijing, LD

Cesarini, C Shon, HK

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Publication Type:: Journal Article
Citation:: Applied Sciences (Switzerland), 2017, 7 (1)
Issue Date:: 2017-01-12

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Field	Value	Language
dc.contributor.author	Yao, M	en_US
dc.contributor.author	Woo, YC https://orcid.org/0000-0003-0847-3067	en_US
dc.contributor.author	Tijing, LD https://orcid.org/0000-0001-9398-6355	en_US
dc.contributor.author	Cesarini, C	en_US
dc.contributor.author	Shon, HK https://orcid.org/0000-0002-3777-7169	en_US
dc.date.issued	2017-01-12	en_US
dc.identifier.citation	Applied Sciences (Switzerland), 2017, 7 (1)	en_US
dc.identifier.uri	http://hdl.handle.net/10453/80772
dc.description.abstract	© 2017 by the authors. Electrospun membranes are gaining interest for use in membrane distillation (MD) dueto their high porosity and interconnected pore structure however, they are still susceptible towetting during MD operation because of their relatively low liquid entry pressure (LEP). In thisstudy, post-treatment had been applied to improve the LEP, as well as its permeation and saltrejection efficiency. The post-treatment included two continuous procedures: heat-pressing andannealing. In this study, annealing was applied on the membranes that had been heat-pressed.It was found that annealing improved the MD performance as the average flux reached 35 L/m2hor LMH (>10% improvement of the ones without annealing) while still maintaining 99.99% saltrejection. Further tests on LEP, contact angle, and pore size distribution explain the improvementdue to annealing well. Fourier transform infrared spectroscopy and X-ray diffraction analysesof the membranes showed that there was an increase in the crystallinity of the polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) membrane also, peaks indicating the α phase ofpolyvinylidene fluoride (PVDF) became noticeable after annealing, indicating some βand amorphousstates of polymer were converted into the α phase. The changes were favorable for membranedistillation as the non-polar α phase of PVDF reduces the dipolar attraction force between themembrane and water molecules, and the increase in crystallinity would result in higher thermalstability. The present results indicate the positive effect of the heat-press followed by an annealingpost-treatment on the membrane characteristics and MD performance.	en_US
dc.relation	http://purl.org/au-research/grants/arc/FT140101208
dc.relation.ispartof	Applied Sciences (Switzerland)	en_US
dc.relation.isbasedon	10.3390/app7010078	en_US
dc.title	Improving nanofiber membrane characteristics and membrane distillation performance of heat-pressed membranes via annealing post-treatment	en_US
dc.type	Journal Article
utslib.citation.volume	1	en_US
utslib.citation.volume	7	en_US
utslib.for	0904 Chemical Engineering	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
pubs.organisational-group	/University of Technology Sydney/Strength - CTWW - Centre for Technology in Water and Wastewater Treatment
utslib.copyright.status	open_access
pubs.issue	1	en_US
pubs.publication-status	Published	en_US
pubs.volume	7	en_US

Abstract:

© 2017 by the authors. Electrospun membranes are gaining interest for use in membrane distillation (MD) dueto their high porosity and interconnected pore structure however, they are still susceptible towetting during MD operation because of their relatively low liquid entry pressure (LEP). In thisstudy, post-treatment had been applied to improve the LEP, as well as its permeation and saltrejection efficiency. The post-treatment included two continuous procedures: heat-pressing andannealing. In this study, annealing was applied on the membranes that had been heat-pressed.It was found that annealing improved the MD performance as the average flux reached 35 L/m2hor LMH (>10% improvement of the ones without annealing) while still maintaining 99.99% saltrejection. Further tests on LEP, contact angle, and pore size distribution explain the improvementdue to annealing well. Fourier transform infrared spectroscopy and X-ray diffraction analysesof the membranes showed that there was an increase in the crystallinity of the polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) membrane also, peaks indicating the α phase ofpolyvinylidene fluoride (PVDF) became noticeable after annealing, indicating some βand amorphousstates of polymer were converted into the α phase. The changes were favorable for membranedistillation as the non-polar α phase of PVDF reduces the dipolar attraction force between themembrane and water molecules, and the increase in crystallinity would result in higher thermalstability. The present results indicate the positive effect of the heat-press followed by an annealingpost-treatment on the membrane characteristics and MD performance.

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http://hdl.handle.net/10453/80772