Development and positron annihilation spectroscopy (PAS) characterization of polyamide imide (PAI)-polyethersulfone (PES) based defect-free dual-layer hollow fiber membranes with an ultrathin dense-selective layer for gas separation

Fu Yun Li, Yi Li, Tai Shung Chung*, Hongmin Chen, Y. C. Jean, Sibudjing Kawi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

Defect-free polymeric dual-layer hollow fiber membranes consisting of an ultrathin dense-selective polyamide imide (PAI) layer and a polyethersulfone (PES) supporting layer have been successfully fabricated in this study for gas separation application. It is observed that a lower outer-layer dope flow rate does not necessarily result in the formation of an ultrathin dense-selective layer upon the PES supporting layer. An optimization in the velocity between the inner-layer and the outer-layer dopes at the exit of the spinneret is essential to minimize additional stresses and defect formation in the outer functional layer. The best gas separation performance of the PAI-PES dual-layer hollow fibers fabricated in this study has an O2/N2 selectivity of 7.73 with a dense-selective layer thickness of 63nm. Positron annihilation spectroscopy (PAS) has been used for the first time to explore the morphology and predict the gas separation performance of PAI-PES based dual-layer hollow fiber membranes. Doppler broadening energy spectra (DBES) from PAS accurately estimate the outer-layer thickness and demonstrate the existence of the multilayered structure of the dual-layer hollow fiber membranes. Besides, the PAS fitted data reveal that the fiber spun under the optimal condition has the densest selective layer, which agrees well with the highest gas-pair selectivity observed under this condition.

Original languageEnglish (US)
Pages (from-to)541-550
Number of pages10
JournalJournal of Membrane Science
Volume378
Issue number1-2
DOIs
StatePublished - Aug 15 2011
Externally publishedYes

Keywords

  • Defect-free dual-layer hollow fiber membrane
  • Doppler broadening energy spectra (DBES)
  • PAI-PES
  • Positron annihilation spectroscopy (PAS)
  • Ultrathin dense-selective layer

ASJC Scopus subject areas

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

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