Pilot study of bioethanol dehydration with polyvinyl alcohol membranes

• Ethanol feed was pretreated with charcoal filtration.
• Crosslinked polyvinyl acetate membranes used in pilot scale bioethanol dehydration.
• Fluxes, separation factors, permeances and selectivities were determined.
• Pervaporation is an energy and cost efficient separation method.

Reduction of production costs is an essential part in the development of more economic and competitive production processes. Membrane techniques have a great potential to decrease the separation costs in the biofuel production. In this research, the feasibility of pervaporative dehydration of bioethanol to be processed for vehicle fuel usage was studied. The focus was on the feed prefiltration, energy integration and permeation behaviour, which are important factors for membrane stability and product quality. In addition, they have a major impact on the energy efficiency of the ethanol dewatering. Experiments were done by using activated carbon filtration equipment and pervaporation unit equipped with hydrophilic crosslinked polyvinyl alcohol (PVA) membranes. Results indicate that active carbon filtration can provide an efficient and up-scalable pretreatment method for the pervaporation feed. Further, the tested pervaporation membranes provided adequate selectivity, not only for the retentate (ethanol), but also for the permeate (water). Low ethanol concentration in the permeate favors intense integration of energy flows and energy savings.