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European Polymer Journal
journal homepage: www.elsevier.com/locate/europolj
Inﬂuence of ionic liquid content on properties of dense polymer membranes
ˇ M. Kohoutová a, A. Sikora b, Š. Hovorka c, A. Randová c, J. Schauer b, M. Tišma d, K. Setnicková a, ˇ ˇ R. Petrickovic a, S. Guernik e, N. Greenspoone, P. Izák a,*
Department of Separation Processes, Institute of Chemical Process Fundamentals, Rozvojová 135, 165 02 Prague 6, Czech Republic Institute of Macromolecular Chemistry, Heyrovského nám. 2, 162 06 Prague 6, Czech Republic c Institute of Chemical Technology, Technická 5, 160 00 Prague 6, Czech Republic d ˇ Faculty of Food Technology, University of J.J. Strossmayer in Osijek, F.Kuhaca 18, 31 000 Osijek, Croatia e Chemada Fine Chemicals, Nir Itzhak D.N. HaNegev 85455, Israel
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Pervaporation was used for removal of butan-1-ol from its 5 wt.% of aqueous solution, at which the concentration of Clostridium acetobutylicum starts to decrease. The polydimethylsiloxane (PDMS) membrane containing 0, 10, 20 or 30 wt.% ofbenzyl-3-butylimidazolium tetraﬂuoroborate ([BBIM][BF4]) ionic liquid was used. Differential scanning calorimetry measurements showed that PDMS-[BBIM][BF4] membranes (though optically homogeneous) contained PDMS and [BBIM][BF4] phases. Pervaporation selectivity increased and total ﬂux through membranes raised moderately with an increased content of [BBIM][BF4] in PDMS-[BBIM][BF4] membranes. Hence, immobilizationof a proper ionic liquid in a membrane results in the creation of pervaporation membranes, effective in the removal of alcohol from fermentation broths. Ó 2008 Elsevier Ltd. All rights reserved.
Article history: Received 5 September 2008 Received in revised form 19 November 2008 Accepted 25 November 2008 Available online 10 December 2008
Keywords: Dense polymer membranes Biofuel FermentationIonic liquids Pervaporation
1. Introduction Biofuels have recently gained industrial interest as a promising alternative to fossil energy sources. Biobutan-1ol displays similar combustion properties as gasoline and could therefore offer the possibility of its direct replacement. Together with acetone and ethanol, butan-1-ol can be produced by the fermentation of biomass thanks to the wellknown bacterium Clostridium acetobutylicum. Under optimized conditions, glucose is fermented to the above mentioned products in a continuous mode [1–3]. A sustained efﬁcient removal of the products by a membrane separation process, namely pervaporation, is therefore needed to maintain a stable growth. Pervaporation, which is considered a forward looking and modern membrane process for separation ofvarious liquids or vapour mixtures, has proved
* Corresponding author. Tel.: +420 296780268; fax: +420 220920661. E-mail address: firstname.lastname@example.org (P. Izák). 0014-3057/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2008.11.043
to be a suitable extraction method for a variety of organic solvents, including butan-1-ol [4,5]. Ionic liquids (ILs) have beenrecognized as a possible environmentally benign alternative to classical organic solvents, mainly due to their thermal stability and ability to solubilize a large range of organic molecules and transition metal complexes [6–9]. ILs are often called ‘‘designer solvents”, because of the facility to change their properties by variation of their components . Polymer membranes containing ionic liquids(PM-ILs) offer a range of possible advantages. Molecular diffusion is much higher in ionic liquids than in polymers and it can be enhanced by a proper choice of IL components. Thus, PM-ILs allow high ﬂuxes and faster separation. In addition, a low cost factor can be added, because only small amounts of ILs are necessary to form the membrane. In our previous work we showed that PM-ILs have...