Reactive Extraction of Lactic Acid by Using Tri-n-octylamine: Structure of the Ionic Phase

Lactic acid is a promising biogenic platform chemical which can be produced by fermentation of cellulose and hemicellulose. However, separating lactic acid from the fermentation broth is extremely costly and technically complex. We therefore investigated whether liquid/liquid extraction of lactic acid with tri‐n‐octylamine is a cost‐effective alternative to the existing downstream processing method. In order to find an answer to this question, the structure of the middle phase of the occurring three‐phase region, which is enriched with up to 20 wt. % lactic acid, was explored. The results of our IR, small‐angle X‐ray scattering and NMR measurements show that this phase is ionic and has a bicontinuous structure. Due to the analogy with bicontinuous microemulsions, it should be possible to further enrich the lactic acid, which could lead to a rethink regarding the design of extraction processes. The main extraction: Lactic acid is a promising biogenic platform chemical that can be produced by fermentation of cellulose and hemicellulose. Liquid/liquid extraction of lactic acid with tri‐n‐octylamine is investigated as a cost‐effective alternative to the existing downstream processing method. To find an answer to this question, the structure of the middle phase of the occurring three‐phase region, which is enriched with up to 20 wt. % lactic acid, is explored.