State-of-the-Art Recovery of Fermentative Organic Acids by Ionic Liquids: An Overview

Abstract

The main achievements of liquid–liquid extraction (LLE) of fermentative organic acids from their aqueous sources using a diverse range of ionic liquids are summarized since the first study appeared in 2004. The literature survey is organized in consideration of the distinct chemical structures of the organic acids. The acids discussed include mono– or dicarboxylic ones (butyric, L-malic and succinic acids), acids bearing both carboxyl and hydroxyl groups (L-lactic, citric and mevalonic acids), and volatile organic acids (mainly acetic acid). Information is given about ionic liquids applied in recovery, and the resultant extraction efficiencies and partition coefficients. As the topic is novel and experimental studies scarce, the selection of the ionic liquids that were tested still seems random. This may well change in the future, especially after improving the ecological and toxicological characteristics of the ionic liquids in order to bring about an “ in situ ” method of extraction without harming the microbial producers of the organic acids.