Separation of acetic acid/water mixtures by pervaporation was attempted over a range of compositions using polydimethylsiloxane (PDMS). aromatic polyamide (PA), and laminated polydimethylsiloxane-aromatic polyamide membranes. PDMS membranes are hydrophobic and acetic acid selective. whereas PA membranes are hydrophilic and water selective. When PDMS and PA membranes were laminated, with PDMS on the top side and in contact with the feed, water selectivity of the bottom PA membrane was intensified. On the other hand, when the PA membrane was on the top side and in contact with the feed, the selectivity was lowered.

Hollow-fiber membranes were prepared to remove volatile organic vapors (VOCs) from a nitrogen or air stream. Conditions were found to spin hollow fibers of high performance for the removal of VOCs. The effect of temperature on the permeation of nitrogen gas and acetone vapor was studied. It was found that nitrogen permeation was governed by diffusion while vapor permeation was governed by sorption. There were two distinct mechanisms for vapor permeation, depending on temperature. Performance data for hollow fibers with and without a silicone rubber coating at the internal surface were compared. The effect of the presence of water vapor in the feed was also studied.

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