Membrane Separation of Ethanol From Bio-Ethanol Containing Gasoline

Polymeric membranes for enriching ethanol from bio-ethanol containing gasoline (BEG) have been developed for the on-board separation process. Poly (vinyl alcohol) (PVA)-base membranes with controlled hydrophilicity were prepared and their separation performances were examined based on the pervaporation experimental studies. The hydrophilicity of the PVA-based membranes was controlled by changing the degree of saponification (the fraction of hydroxyl groups). The PVA-based membranes showed high selectivity for ethanol, of which the concentration in the permeate side was higher than 90% for a wide range of the feed composition studied. Increasing the hydrophilicity of the membranes increased the ethanol selectivity over a model hydrocarbon (n-heptane), and the flux decreased. The highest flux observed was as high as 100 g/m²/h. The results suggest that the membranes can be applicable for the separation processes of ethanol from BEG.