Comparison of an Ion Exchanger and an In-House Electrodialysis Unit for Recovery of L-Lactic Acid from Fungal Fermentation Broth

摘要

Lactic acid has long been widely used in many applications. Currently, the worldwide market is increasing due to the discovery of biodegradable polylactic acid. In this work, L-lactic acid separations from filamentous fungal fermentation broth using ion-exchange cnromatography and in-house electrodialysis, were studied and compared. Dowex Marathon WBA was used for the lactic acid separation. The adsorption equilibrium followed a Langmuir isotherm. The optimal conditions for lactic acid adsorption in a fixed-bed column were at pH 6.0, and 0.8 mL/min and elution by a mixture of 1.0 M sulfuric acid and 1.0 M phosphoric acid in a ratio of 30:70 at 0.3 mL/min. The final lactic acid recovery was 76 % with 90 % purity. A laboratory scale in-house electrodialysis apparatus was constructed with an effective membrane area of 2.925 · 10~(-3) m~2. The effects of feeding solution concentration, flow rate, pH of the fermentation broth, and applicable voltage were studied. Under the optimal conditions, lactic acid recovery was 92 % with 100 % purity and a specific energy consumption of 0.6122 kWh/kg.