Removal and recovery of solvents from fermentation broth by pervaporation using liquid membrane

Liquid membranes can achieve much higher selectivity for some small molecules such as acetic acid, ethanol, butanol, etc. Liquid membranes immobilized in novel porous hollow fiber-based membranes as a support for the pervaporation process to increase the VOC selectivity and membrane stability were studied. Volatile fermentation byproducts such as acetone, butanol and ethanol present in low concentrations in synthetic aqueous solutions were separated by novel liquid membranes. The liquid membrane with model solutions (containing acetone-butanol-ethanol (ABE)) and a filtered solution from a fermentation broth (from ABE fermentation) were tested by the pervaporation process. Very high selectivities for the solvents were obtained in the permeate especially at > 50°C. The selectivities of butanol, acetone, and ethanol achieved were 275, 220, and 80, respectively, with 11, 5, and 1.2 g/sq m-hr for the mass fluxes of butanol, acetone, and ethanol, respectively, at 54°C for a feed solution containing 1.5 wt % butanol, 0.8 wt % acetone, and 0.5 wt % ethanol. This is an abstract of a paper presented at the AIChE Annual Meeting (Salt Lake, UT 11/4-9/2007).