ARS | Publication request: A novel method to fabricate high permeance, high selectivity thin-film composite membranes

Submitted to: Journal Membrane Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2011
Publication Date: July 7, 2011
Citation: Offeman, R.D., Ludvik, C.N. 2011. A novel method to fabricate high permeance, high selectivity thin-film composite membranes. Journal Membrane Science. 380: 163-170.

Interpretive Summary: To be commercially attractive, permeation membranes must have high flux (throughput). This is achieved by making a very thin separating layer which covers a microporous supporting layer. Such thin-film composite membranes suffer reductions in flux and separating ability due to flow resistance in the support layer. We have developed a novel fabrication method for thin-film composite membranes which permits enhanced selectivity and flux. A patent application was filed. The method is generally applicable to a wide range of membrane types. In particular, it is aimed at recovery of alcohols from fermentation broths, and hence is applicable to biofuels production.

Technical Abstract: We report a thin-film composite (TFC) membrane fabrication method based on transfer of a pre-formed, cured active layer onto a microporous support. This method can be used with supports of relatively high pore size and porosity, thus reducing mass transfer resistance from the support. Ethanol-selective pervaporation from aqueous solution was chosen for the evaluation of the TFC membranes. In comparing results with a 10 µm polydimethylsiloxane (PDMS) active layer on two supports, a TFC made with a high porosity support showed 52 % higher total permeance than that of a TFC made with a low porosity support. While the TFC with the low porosity support showed a selectivity (ratio of ethanol permeance to water permeance, mass basis) of 1.68, the TFC with the high porosity support had a selectivity of 1.93, similar to the selectivity of a thick, unsupported PDMS membrane. ZSM-5/PDMS mixed matrix active layer TFCs were also prepared, and showed significantly enhanced performance compared to unfilled PDMS TFCs. A method for commercial fabrication is proposed.