Extraction of levulinic acid using tri-n-butyl phosphate and tri-n-octylamine in 1-octanol: Column design

• Extraction of levulinic acid using phosphoric and aminic extractants in active diluent was investigated.
• A comparison was done between the extractants based on extraction efficiency.
• A maximum KD of 9.571 with 90.54% recovery of acid was obtained.
• Minimum solvent to feed ratio required for 90% recovery, NTS, height and diameter of the extraction column were calculated.

The reactive extraction of levulinic acid using two different extractants [tri-n-butyl phosphate (TBP) and tri-n-octylamine (TOA)] dissolved in 1-octanol was investigated at 298 K. Using the equilibrium data, the distribution coefficient (KD), extraction efficiency (%E) and loading ratios (Z) were calculated. TOA provided highest KD values with 1-octanol. A maximum KD was obtained as 9.571 using 0.689 mol/kg TOA while 90.54 % of the initial levulinic acid was extracted. Increasing the initial acid concentration resulted in a decrease in the extraction efficiency. Loading ratios were found to be less than 1 for TBP while both types, i.e. 1:1 and 2:1 acid-amine complexes were expected to form with TOA. The feasibility of the extraction process was assessed by calculating minimum solvent to feed ratio required for 90% recovery of levulinic acid, number of theoretical stages, height and diameter of the extraction column.

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