Exploring Membrane Pervaporation Separation: A Review on Obtaining Combustible Ethanol and Butanol from Fermentation Broths

Pervaporation is an advanced membrane-based separation technique to purify complex mixtures (e.g., those with azeotropes or thermolabile compounds) which would otherwise require involved sequences of conventional separation operations such as distillation or extraction. Pervaporation is particularly well suited for some alcohol + water mixtures since it is not limited by the presence of the azeotrope, while improving energy efficiency and reducing operating costs. Furthermore, its coupling with biomass fermentation for biofuels production alleviates product inhibition, thereby increasing yield by up to 67%. This review focuses on the performance of pervaporation membranes, primarily those based on polydimethylsiloxane (PDMS), for the separation of alcohols from fermentation broths, reporting flux values of up to 203.76 g/m² h and a separation factor of up to 147. Additionally, the effects of composition and temperature are evaluated. Factors influencing process efficiency are also analyzed, and emerging technologies, new bacterial strains, and biomass sources are highlighted as strategies to enhance alcohol fuel production. Finally, examples are presented where pervaporation has significantly contributed to improving biofuel production.