Pervaporation performance of composite poly(dimethyl siloxane) membrane for butanol recovery from model solutions

Butanol has potential to become an important renewable transportation fuel and feedstock chemical in the future. However, low yield and high separation costs are the main obstacles in feasible industrial scale biobutanol production by the acetone–butanol–ethanol (ABE) fermentation process. Both problems can be overcome by using pervaporation as the product removal technique. The performance of a polydimethylsiloxane (PDMS) membrane with a support layer of polyacrylonitrile (PAN) was studied for the removal of acetone, butanol and ethanol from dilute aqueous model solutions. The effect of feed composition on permeation fluxes, permeances, separation factors and pervaporation separation indices was investigated by using binary aqueous solutions of acetone, butanol and ethanol followed by experiments with different aqueous ternary mixtures and quaternary ABE–water mixture. At feed temperature of 42 °C, partial fluxes and permeate concentrations were found to be in the order of acetone≈butanol>ethanol, while the permeance order was butanol>ethanol≈acetone. Separation factors were in the range of 21–26, 22–29 and 5–7 for acetone, butanol and ethanol, respectively. Results indicate that the tested membrane has potential to be used in the ABE fermentation process.