Influence of ionic liquid content on properties of dense polymer membranes

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.% of benzyl-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, immobilization of a proper ionic liquid in a membrane results in the creation of pervaporation membranes, effective in the removal of alcohol from fermentation broths.