Pervaporative Separation of Bioethanol Using a Composite Hollow Fiber Membrane

In this study, a composite hollow fiber membrane with a thin PDMS active layer on polyetherimide macroporous structures was used for pervaporative separation of ethanol from fermentation broth. Pervaporation was carried out in model solutions of ethanol/water binary mixtures with a wide concentration range to investigate the influence of temperature and concentration on the process performances. The ethanol flux values increased linearly due to the increasing driving force of the concentration difference, while the separation factor sharply decreased in dilute solutions. The influence of temperature on permeation performance showed that the increase of ethanol flux with temperature was due to increased swelling capacity and weak water adsorption. In this study, bioethanol produced from fermentation using Saccharomyces cerevisiae was used as feed for pervaporation of the composite hollow fiber module. The pervaporative ethanol separation from the fermentation broth did not show a significant concentration polarization, nor a fouling effect on the hollow fiber membranes. A higher ethanol flux was observed in bioethanol pervaporation, than in the model solution, which can be understood in terms of the hydrophobic surface of the PDMS membrane, and rejection due to the presence of materials in the fermentation broth.