Reactive extraction and equilibrium analysis of lactic acid in a packed column

Abstract

In this study, reactive extraction was investigated to develop an effective and economic separation process of lactic acid from fermentation broth. This study consisted of two branches. First, reaction mechanism was investigated to interpret equilibrium data by a modified mass action model. Active diluents used were classified into three parts. Water enhanced solubilities of lactic acid was explained by physical solubility of lactic acid. Second, reactive extraction of lactic acid was performed in a packed column. Characteristics in a packed column were investigated and phenomena of mass transfer were investigated based on equilibrium curves. Details of each branch were summarized as follows. In this study, trioctylamine(TOA) was selected as an extraction agent for the reactive extraction of lactic acid. The appropriate selection of active diluent can help the reactive extraction and the stripping process due to the affinity of reaction complex. In this study, methylene chloride and 1-chlorobutane were used due to appropriate boiling point. Extraction efficiencies were sharply increased with an increase of composition of active diluent. However, the variation of inactive diluent has little influence on extraction efficiencies except polar chlorobenzene. The effect of temperature was not large in comparison with the effect of composition in spite of large variation of temperature. Curves of equilibrium and hydration were obtained at various temperatures and concentrations of TOA. From these data, we divided active diluents used into three classes such as active diluents containing chlorine atoms, carbon bonded oxygen donor active diluents and phosphorus bonded oxygen donor active diluents. This classification was based on characteristic groups of active diluents. The amounts of lactic acid and water in the organic phase were largely affected by the physical extraction of active diluents. The relations between coextracted water and lactic acid extracted were r...