REACTIVE EXTRACTION OF PROPIONIC ACID USING TRI-n-OCTYLAMINE

Abstract

Reactive extraction of propionic acid using tri-n-octylamine (TOA) in 1-decanol and 2-octanol was studied. Physical and chemical extractions from aqueous solution of acid were presented. The extraction of propionic acid from aqueous solutions using TOA in 1-decanol and 2-octanol, respectively, resulted in a degree of extraction as high as 92%. The effect of temperature was studied and it was found that as the temperature was raised from 305 to 353 K, K_E decreased from 30.11 to 11.85 and 19.44 to 10.23 in the case of 30 and 40% TOA, respectively, in 1-decanol and 28.57 to 11.32 and 21.99 to 8.70 in the case of 30 and 40% TOA, respectively, in 2-octanol. TOA in both diluents was found to be more effective at pH values less than 4. Increasing the pH from natural pH to 7 was found to severely affect the extraction. Different salts (NaCl, Na₂SO₄, K₂HPO₄) and substrate sources (lactose and dextrose) were selected to study their effects on the reactive extraction of propionic acid. The presence of salts lowers the extraction, but substrate sources were found to have no effect on the extraction of propionic acid using TOA in either diluent. Six model solutions were prepared containing various concentrations of salts and substrate to get a real view of extraction. Extraction from the model solutions was lower than that observed in the aqueous solutions. However, the values are still high enough to have a sustainable extraction.

Keywords:

• Fermentation
• pH
• Propionic acid
• Reactive extraction
• Salts
• Temperature

Acknowledgment

Department of Science and Technology (DST), India, Young Scientist Project, SR/FTP/ETA-43/2005, Reactive Extraction of Propionic Acid (Dr. Kailas L. Wasewar, VNIT Nagpur, India) is acknowledged.