A new microbial polysaccharide membrane for ethanol dehydration by pervaporation

In this study, a new microbial exopolysaccharide (EPS) membrane obtained from a low cost and abundant carbon source, the glycerol by-product of the biodiesel industry, was used for ethanol dehydration by pervaporation. Two types of membranes were prepared: homogeneous membranes obtained directly from the fermentation broth and crosslinked with tricloroacetic acid (EPS), and composite membranes with a thin film of crosslinked EPS supported in polyethersulfone (EPS-PES). These membranes were characterized in terms of their morphological structure, resistance to solvents and mechanical properties. They show a high affinity towards water, good chemical resistance towards organic solvents and adequate mechanical properties. Pervaporation experiments were performed using both types of membranes for different water concentration in the feed stream (5.0 to 10.0 wt%) at a constant temperature of 30 °C. The membranes developed, in particularly the composite EPS-PES membrane, exhibit a high potential for ethanol dehydration, since a water/ethanol selectivity of 3000 at 5.0 wt% water concentration in the feed was achieved. Considering the good results obtained, these new membranes will be also evaluated for the dehydration of other industrially relevant solvents, for separation of polar and non-polar compounds in organic mixtures, and also for solvent-resistant nanofiltration processes.