Reactive extraction of lactic acid from sweet sorghum silage press juice

Fermentation of residues or side streams can be used to produce valuable products, such as carboxylic acids. Reactive solvent extraction is widely studied as isolation method for lactic acid from fermentation broths. Here, we investigate the reactive extraction of lactic acid from sweet sorghum silage press juice using different extractants, modifiers, and diluents. Besides a high extraction efficiency, a low crud formation with this highly complex raw material is targeted. Depending on the solvent phase composition, an extraction efficiency of up to 41.1 % was reached using DOA/ALIQ:1–octanol:n–nonane. The crud layer was highly influenced by the applied diluent and amounted to 2.6–42.3 vol% of the total mixture volume. The back-extraction experiments showed, that up to 98.2 % of lactic acid were recovered. Summarizing, the results show that reactive solvent extraction of lactic acid is applicable to highly complex process streams, and crud formation can be reduced by adjusting the solvent phase composition.