Fermentative organisms produce a range of compounds in addition to the desired product. For example, in addition to ethanol, standard yeast produce longer straight-chained and branched alcohols and organic acids. Additionally, biomass pretreatment process, particularly acid-based treatments, can introduce organic acids into the sugar feed stream to the fermentor. Carboxylic acids, such as acetic acid and succinic acid, are commonly encountered in the conversion of biomass to ethanol and other biofuels. Pervaporation using mixed matrix membranes has proven to be a selective method of removing alcohols from fermentation broths[1]. Such membranes are prepared by dispersing ethanol-selective zeolite particles into a polymer matrix. The carboxylic acids and longer chain alcohols present in the broths, however, compete with ethanol for adsorption sites within the zeolite channels and this affects the permeability and selectivity of the mixed matrix membrane[2].

In this presentation, the effect of actual fermentation broths on the pervaporation performance of mixed matrix membranes will be reported along with methods for mitigating the effect of broth components on membrane performance.

[1] L.M. Vane, V.V. Namboodiri, and T.C. Bowen “Hydrophobic zeolite-silicone rubber mixed matrix membranes for ethanol-water separation: Effect of zeolite and silicone component selection on pervaporation performance,” Journal of Membrane Science, 308, 230-241 (2008).

[2] T.C. Bowen, R.G. Meier, and L.M. Vane, “Stability of MFI zeolite-filled PDMS membranes during pervaporative ethanol recovery from aqueous mixtures containing acetic acid,” Journal of Membrane Science, 298, 117-125 (2007).

*This is an abstract of a proposed presentation and does not necessarily reflect USEPA policy.