The effect of supercritical CO2 on the permeation of dissolved water through PDMS membranes

Andrew Shamu, Henk Miedema, Kitty Nijmeijer, Zandrie Borneman (Corresponding author)

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Abstract

Water vapor permeation under supercritical carbon dioxide (scCO2) conditions through dense polydimethylsiloxane (PDMS) was investigated up to pressure of 185 bars to evaluate the regenerability of scCO2 as desiccant to dehydrate fresh products that are prone to product deterioration during conventional drying. This study experimentally examined the impact of concentration polarization on the H2O vapor permeation through dense PDMS membranes in the presence of sub- and supercritical CO2. The results were compared to a system containing N2 instead of CO2. For the CO2 system, the residual mass transfer resistance, which excludes the membrane layer resistance, decreased down to zero with increasing feed pressure, at 90 bar. This is the result of the convergence of the H2O contents of the feed bulk and permeate, which leads to a change of the main H2O transport mechanism within the feed boundary layer from diffusion to convection. Here the H2O and CO2 molecules are transported with comparable speed towards the membrane surface. For the system with N2, the opposite trend was found, due to the maintained significant difference in transport speed between H2O and N2 even at elevated pressures. Consequently, the water vapor transport rate through the PDMS membrane is governed by the type of matrix fluid (CO2 or N2).

Original languageEnglish
Pages (from-to)145-152
Number of pages8
JournalJournal of CO2 Utilization
Volume35
DOIs
Publication statusPublished - Jan 2020

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Keywords

  • Concentration polarization
  • Dense membranes
  • Permeability measurement
  • Polydimethylsiloxane (PDMS)
  • Supercritical carbon dioxide
  • Water vapor transport

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