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Title: Explorations of combined nonsolvent and thermally induced phase separation (N-TIPS) method for fabricating novel PVDF hollow fiber membranes using mixed diluents
Authors: Zhao, Jie
Chong, Jeng Yi
Shi, Lei
Wang, Rong
Keywords: Engineering::Civil engineering
Issue Date: 2018
Source: Zhao, J., Chong, J. Y., Shi, L., & Wang, R. (2019). Explorations of combined nonsolvent and thermally induced phase separation (N-TIPS) method for fabricating novel PVDF hollow fiber membranes using mixed diluents. Journal of Membrane Science, 572, 210-222. doi:10.1016/j.memsci.2018.11.015
Journal: Journal of Membrane Science
Abstract: The combination of nonsolvent and thermally induced phase separation (N-TIPS) method has shown promising ability in harvesting the features from the nonsolvent induced phase separation (NIPS) and thermally induced phase separation (TIPS) processes for developing membranes with a tailorable surface pore structure. However, previous approaches have been subjected to either the formation of macrovoids or dense layer due to the dominant NIPS effect, or required sophisticated instruments and operation skills. In this work, a facile attempt was carried out to fabricate novel polyvinylidene fluoride (PVDF) hollow fiber membranes with tunable surface pore structure while maintaining the narrow pore size distribution and mechanical strength. A modified N-TIPS method was developed by using mixed diluents: dimethyl phthalate (DMP) as a water-immiscible poor solvent for TIPS process, and triethyl phosphate (TEP) as a water-miscible neutral solvent to bridge the TIPS and NIPS processes. To further control the membrane formation especially near the membrane surface, an amphiphilic additive Pluronic F127 was also added as a potential pore-former and surface hydrophilicity modifier. PVDF hollow fiber membranes with a highly porous structure and a narrow pore size distribution were successfully synthesized by using TEP and Pluronic F127 in the N-TIPS process. The mechanism of N-TIPS process was thoroughly discussed. The water permeability of the membrane increased significantly from 389 ± 30–922 ± 36 L m–2 h–1 bar–1, with overall porosity improved from 50 ± 2.2–69 ± 2.9%, and a mean pore size of ~ 0.18 µm. The membranes produced by N-TIPS method also exhibited a good tensile strength ranging from 5.6 ± 0.1–6.5 ± 0.2 MPa, showing a great potential for a broad range of water applications after further modifications. Besides, the formation of piezoelectric β-phase crystals of the PVDF membrane was observed when the mixed diluent was used, which sheds light on the possible applications of resultant membranes in electrochemical separation process.
ISSN: 0376-7388
DOI: 10.1016/j.memsci.2018.11.015
Rights: © 2018 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.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:CEE Journal Articles

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