Recovery of 3-hydroxypropionic acid from organic phases after reactive extraction with amines in an alcohol-type solvent

Reactive extraction is a well-known method for the recovery of organic acids from dilute streams. The extraction through complex formation with amines is followed by its back-extraction. Their affinity for amine extractants makes their back-extraction a limiting step. The case of 3-hydroxypropionic acid is addressed here. Three methods were compared: salts additions, diluent swing and temperature swing. Mineral bases led to complete 3-HP recovery but as a salt. Diluent swing was tested using n-hexane as the anti-solvent. Results showed that increasing the n-hexane content led to a great increase of 3-HP recovery. However, high recovery yields are associated with high dilutions. The temperature was varied from 4 to 140 degrees C and it led to a high decrease of the acid-amine complex formation. Our thermochemical study showed an apparent heat of reaction of - 25.3 kJ/ mol and, at 140 degrees C, 78% of 3-HP can be recovered in a single step.