Ethanol crossover through alkali-doped polybenzimidazole membrane

New reproducible method for investigation of ethanol permeability of polymeric membranes in alkali media has been developed. Using the developed method ethanol crossover through KOH doped poly[2,2′-(4,4′-diphenylether)-5,5′-bibenzimidazole] (DOPBI) has been investigated with respect to alkali concentration. The permeability value, obtained in 3 M KOH was 8.6 × 10−8 cm2 s−1, which further decreased with the raise of alkali concentration. Preliminary modeled estimation showed that ethanol crossover would drop by a factor of 4 if discharge current of the cell raised by approximately 1 mA cm−2. The developed method can be expanded to measuring polymeric membrane permeability to alcohols in acidic conditions and various aqueous solutions.