Influence of support layer and PDMS coating conditions on composite membrane performance for ethanol/water separation by pervaporation

Parimal V. Naik, Roy Bernstein, Ivo F.J. Vankelecom

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

A systematic study was performed on the combination of support properties and polydimethylsiloxane (PDMS) coating conditions for the lab-scale preparation of a defect-free, thin film composite membrane for organophilic pervaporation. Support layers having comparable surface porosities were prepared from three polymers with different chemical composition (PVDF, PSF, PI). Their exact role on the deposition of the PDMS coating (i.e., wetting and intrusion) and the final membrane performance (i.e., effect on mass transfer of the permeants) was studied. The crosslinking behavior of dilute PDMS solutions was studied by viscosity measurements to optimize the coating layer thickness, support intrusion and wetting. It was found essential to pre-crosslink the PDMS solution for a certain time prior to the coating. Dip time for coating the PDMS solution on the supports was varied by using automated dip coating machine. The performance of the synthesized membranes was tested in the separation of ethanol/water mixtures by pervaporation. Both flux and selectivity of the membranes were clearly influenced by the support layer. Resistance of the support layers increased by increasing the polymer concentration in the casting solutions of the supports. Increasing the dip time of the PDMS coating solution led to increased selectivity of the composite membranes. Scanning Electron Microscopy analysis of the composite membranes showed that this leads to a minor increase in the thickness of the PDMS top layer. Top layer thickness increased linearly with the square root of the dip time (t0.5) at a constant withdrawal speed of the support.

Original languageEnglish
Article number43670
JournalJournal of Applied Polymer Science
Volume133
Issue number28
DOIs
StatePublished - 20 Jul 2016
Externally publishedYes

Keywords

  • films
  • membranes
  • separation techniques

ASJC Scopus subject areas

  • Chemistry (all)
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry

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