Solvent screening for liquid-liquid extraction of levulinic acid from aqueous medium

Lignocellulosic material represents an attractive raw material to the synthesis of different compounds with industrial interest. Among these compounds, levulinic acid has gained considerable attention. Nonetheless, the difficulty of separating it from the aqueous media and the low yield often obtained in its synthesis hinder its commercial production. The liquid-liquid extraction process can be an effective approach to overcome these limitations. The transfer of the levulinic acid from the aqueous medium to an organic phase avoids the contact of the acid with the catalyst, minimizing side reactions and simplifying the subsequent separation process. For this purpose, the solvent choice is of utmost importance. This work aimed to identify potential solvents for the extraction of levulinic acid from the aqueous medium. An initial screening was conducted using the COSMO-SAC model to estimate partition coefficients of levulinic acid in thirty different organic solvents. The highest partition of levulinic acid in the organic phase was calculated for 2-tert-butylphenol, MIBK and 2-heptanone. However, experimental data obtained for these systems showed that the model overestimated the partition coefficient values. The mutual solubilities between the two phases shift the activity of levulinic acid in the aqueous phase, which made the predictions inaccurate.