Effects of orientation relaxation and bore fluid chemistry on morphology and performance of polyethersulfone hollow fibers for gas separation

Jian Jun Qin*, Tai-Shung Chung

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Hollow fibers with ultrathin skins for gas separation have been fabricated from a binary (37wt.% PES in NMP) solution. Effects of orientation relaxation and bore fluid chemistry on morphology and performance of the membranes have been investigated. An outer skin membrane was successfully fabricated for the first time from this binary spinning dope with a very short air gap of 0.5cm and with a bore fluid of 80wt.% NMP in water. The experimental results showed that the permeances of all the tested gases for the unwet-spun fiber were much higher than that of the wet-spun fiber but the selectivities of the former membrane were lower than that of the latter, which indicates that the unwet-spun fiber had a much less dense outer skin than the wet-spun fiber. The results confirmed that the molecular orientation induced within the spinneret at the outer surface of the nascent fiber could relax in the very short air gap, which originally could be frozen into the wet-spun fiber. For the wet-spun fibers, the permeances of all the tested gases decreased while the selectivities increased when bore fluid rate decreased or when the concentration of solvent in the bore fluid decreased. It was concluded that the chemistry of bore fluid had a significant effect on the microstructure and performance of final fibers. The newly developed PES hollow fiber had a selectivity of 5.7 for O2/N2 with a permeance of 11.3×10-6cm3(STP)/cm2scmHg for O 2 at room temperature and the effective thickness of the membrane skin layer was 360Å from the calculation. Aging study (in air) on different fibers showed that permeances of O2 declined by ∼50% and selectivities of O2/N2 decreased by 10-15% after 130 days then leveled off.

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalJournal of Membrane Science
Volume229
Issue number1-2
DOIs
StatePublished - Feb 1 2004

Keywords

  • Bore fluid chemistry
  • Gas separation
  • Hollow fiber membranes
  • Orientation relaxation
  • Polyethersulfone

ASJC Scopus subject areas

  • Biochemistry
  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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