Current Advances in Separation and Purification of Second-Generation Lactic Acid

Lactic acid is an important chemical as starting chiral material in various applications. It has increased value in the global market. Different studies have presented the possibility to obtain rich lactic acid solutions with high isomeric purity (S-form) from second-generation (2G) feedstocks. The used downstream process is crucial, not only in terms of the overall cost but also for the achievement of high product purity, suitable for high-value applications. This review provides an overview of the current state-of-the-art on the separation and purification methods of lactic acid derived from the fermentation of second-generation feedstocks. The traditional precipitation method, solvent extraction, affinity-related processes, membrane separation, reaction-separation systems, salting-out extraction and molecular distillation are the main processes investigated so far. The different approaches are discussed in terms of lactic acid recovery yield and purity as well as their environmental impact.