Sandwich Structure Membrane with Enhanced Anti-Swelling Property and Mechanical Strength for Bioethanol Separation by Pervaporation

To improve the membrane’s anti-swelling and anti-mechanical damage properties, one polypropylene (PP) membrane was integrated into the conventional dual-layer polydimethylsiloxane/polyamide (PDMS/PA) membrane, forming a new sandwich structure PP/PDMS/PA composite membrane with better durability during the ethanol separation from the practical fermentation broth. In the sandwich structure, the top PP layer protected the fragile layer, PDMS layer, which was inlaid outside the PDMS/PA membrane, from being directly exposed to the fermentation broth and the external mechanical damage. The middle PDMS layer was the separation layer and glued the PP and PA layers together. The bottom PA layer was the supportive layer. The swellings of the PP/PDMS/PA membrane in water, ethanol, and fermentation broth were decreased by 21, 6, and 17%, respectively, compared with those of the PDMS/PA membrane. The tensile strength, Young’s modulus, breaking strength, and anti-impact property of the PP/PDMS/PA membrane were increased by 223, 18, 724, and 196%, respectively.