Salting-out effects on vanillin extraction by supercritical carbon dioxide from aqueous vanillin solution containing salts

The effect of salting-out (i.e., a decrease in solubility by the addition of salts) on the vanillin partition coefficient was investigated when vanillin was extracted using supercritical CO2 from a vanillin aqueous solution containing salts (0-0.9 mol/kg) at 40 degrees C and 20 MPa. The addition of salts (i.e., NaCl, KCl, Na2SO4, and (NH3)(2)SO4) enhanced the transfer of vanillin to supercritical CO2, which led to an increase in the partition coefficient. Solubility measurements revealed that the addition of salts decreased the solubility, and the degree of salting-out was different for different salts and concentrations. A correlation between the solubility (S) and the partition coefficient (K) showed that ln K has a linear relationship with ln S at constant temperature and pressure conditions. In addition, it was confirmed that the vanillin salting-out effect and the partition coefficients could be correlated to specific salt parameters, such as the valence and ionic radius. (C) 2019 Elsevier B.V. All rights reserved.