Reactive extraction of succinic acid by amine extractants

Abstract

In this study, reactive extraction by reversible reaction of amine extractants was investigated for the development of an effective and economic separation process of succinic acid from fermentation broth. Tertiary amines act as complexing agents with the succinic acid that facilitates the distribution of succinic acid into organic phase. The extraction characteristics with various factors were investigated. The extractability for succinic acid was increased with the amine concentration and the polarity of diluent. And the extractability for succinic acid was increased with the chain length of tertiary amine in active diluent however, vice versa in inactive diluent. In the inactive diluent, such as n-heptane, the steric hindrance and aggregate formation were important factors determining the extractability of tertiary amine. Based on these results, the blended amine consisted of a short chain tertiary amine and a long chain tertiary amine was developed. In mixed diluents composed of active/inactive diluent, the extraction efficiency of new blended amine was higher than that of single kind of amine. The coextracted water into organic phase was proportional to the polarity of diluent and the chain length of tertiary amine. The solubility of acid-amine complex was enhanced by the coextrated water. The relation between the amount of coextracted water and the extractability for succinic acid was explained by introducing sensitivity index that is as the measure of water enhanced solubility of succinic acid. For the fast separation of succinic acid the Predispersed solvent extraction (PDSE) process by colloidal liquid aphrons (CLAs) was carried out and then, compared with conventional reactive extraction. Aphron is defined as a distinct unit of fluid, encapsulated by a thin film of another fluid. The PDSE process by CLAs enhanced the extractability of organic phase at neutral pH range that is the operating pH of practical fermentation process. And the structure of CLA...