Continuous recovery process of succinic acid from fermentation broth using reactive extraction in hollow fiber membrane contactor

Abstract

Succinic acid, a four carbon dicarboxylic acid, has received a great deal of attention for many years because it can be used as a raw material for biodegradable polymer. As an alternative to the petrochemical-based process, the intensive study on organic acid production through the fermentation process is in progress. In this study, we investigated reactive extraction of succinic acid (SA) from aqueous solutions using a hollow fiber membrane contactor. Tri-n-octylamine(TOA) and 1-octanol were employed as extractant and diluent, respectively. We verified the effect of volumetric flow rate of shell side, initial concentration of succinic acid and TOA, pH of feed solution and salts on forward extraction and concentration of SA/TOA and stripping solution on backward extraction. The effect of TOA concentration on forward extraction was dominant among the various operating variables considered. The extraction rate was proportional to the amine concentration. At the pH above the $pK_{a_1}$ (4.21) of succinic acid, extraction performance was significantly reduced and even worse above $pK_{a_2}$ (5.64) approaching zero in extraction performance. There was no remarkable effect of volumetric flow rate on extraction and stripping in measured interval. Simultaneous forward and backward extraction was carried out at optimized conditions which are determined by individual forward and back ward extraction. Total input concentration of succinic acid was about 150 g/L and final concentration of sodium succinate in stripping solution was about 177 g/L. In simultaneous extraction from fermentation broth final concentration of sodium succinate was about 68.1g/L. As a result, the developed process enabled to producing the succinic acid with high yield (86 %) by controlling concentration of feed solution, pH, transmembrane pressure difference.