(275a) Separation of Volatile Organic Acids from Fermentation Using Non-Ionic Surfactants

Volatile organic acids (VOAs), such as acetic, propionic, butyric, and lactic acids, are high value compounds that can be used as precursor for a wide range of applications. These applications include food additive and preservative, solvent, plasticizer, perfume, polymer synthesis, synthetic fabrics and fibers, pharmaceutical and biofuels. VOAs can be produced through anaerobic fermentation, and is typically recovered by precipitation followed by re-acidification using sulfuric acid. This process, however, produces large amount of solid slurry and calcium sulfate as waste. Alternatively, liquid-liquid extraction can be applied to recover VOAs from fermentation broth. Among the solvents studied for VOAs extraction include long-chain aliphatic amines and fatty alcohols (or their mixture) due to their high distribution coefficients. Previous study by the authors indicated that non-ionic surfactant, particularly a mixture of alcohol ethoxylates, can also be used for extraction of butyric acid from aqueous medium. This study extends the previous work by establishing the phase equilibria of lactic acid with various non-ionic surfactants. This will be done to evaluate the applicability of these surfactants for liquid extraction of lactic acid, as indicated by distribution coefficients and separation factors. The non-toxic and biodegradable characteristics of non-ionic surfactants could be useful as well for in situ extraction or extractive fermentation of VOAs.