Investigation of pervaporation performance of POMS membrane during separation of butanol from water and the effect of added acetone and ethanol

In this work the pervaporation performance of a POMS [polyoctylmethyl siloxane] membrane to separate acetone-butanol-ethanol from aqueous solutions was studied. Butanol – water solutions with the addition of acetone and ethanol were analyzed to investigate the effect of multicomponent feed systems
on the pervaporation performance of the membrane. Additionally membrane performance in contact with real fermentation broth was investigated. For the binary mixture transmembrane butanol flux increases with increasing feed temperature and feed concentration. Over the whole investigation range the membrane is selective for butanol. It was observed that positive flux coupling for butanol as well as water flux occurs when acetone is present in the feed solution. This results in higher permeance for butanol and water in the investigated range, but similar selectivities. For the quaternary mixture total permeation flux increased, while butanol flux stayed the same. Pervaporation of the real fermentation broth showed, that component permeances increased drastically resulting in high selectivities of 9.8, 3.8 and 0.9, for butanol, acetone and ethanol respectively. This change in membrane performance makes
pervaporation with POMS optimal for the product recovery during ABE-fermentation.