Recovery of succinic acid by predispersed solvent extraction

Abstract

In this study, predispersed solvent extraction (PDSE) by colloidal liquid aphrons was investigated for the recovery of succinic acid from aqueous solution. Tertiary amine, trioctylamine (TOA), was used as extractant. TOA acts as complexing agents with succinic acid that facilitates the distribution of succinic acid into organic phase. The extraction characteristics of succinic acid with various pH were investigated. The loading values for succinic acid in PDSE by CLAs increased with increasing the pH values in aqueous phase due to increasing concentration of the undissociated succinic acid. Therefore, the loading value decreased dramatically at pH 4.2, the pKA1 value of succinic acid. The extraction efficiency of PDSE is similar as mixer/settler while extremely short contact time due to the vast surface area of CLAs. Salts generally contained in fermentation broth can affect the reaction between amine and acid. Sodium and magnesium source as a form of sodium chloride and magnesium chloride hexahydrate are essential nutrients to the microorganism. Therefore, the effect of sodium chloride and magnesium chloride hexahydrate on the extractability of TOA was investigated. Sodium chloride causes noticeable decreasing extractability. The effect of magnesium chloride hexahydreate on extractability was ignorable in the generally used concentration range. The stripping method of succinic acid after reactive extraction was investigated. The temperature-swing method was not effective. Using a sodium chloride solution was proposed as a new stripping method of succinic acid from organic phase. The stripping efficiencies at 6g/L NaCl solution was about 2 times higher than those at distilled water. The effect of pH and salt in continuous phase on the stability of CLAs was measured. The stability of CLAs decreases with decreasing the pH value. It is due to electrostatic interactions associated with the surfactant head-groups. However, CLAs are stable at near neutral pH range a...