Supercritical Fluid Extraction of Carotenoid from Microalgae with Projected Thermodynamic Models (RESEARCH NOTE)

In this study, two thermodynamic models (regular solution theory and equation of state) were applied to obtain carotenoid solubility in the supercritical carbon dioxide solvent. Theoretical data obtained from the models were compared with the experimental data extracted from a published paper. The use of equation of state as an empirical correlation for collating and predicting liquidliquid and liquid-dense fluid equilibrium is discussed. It is concluded that the estimation of some parameters required for these calculations would be difficult if the solute (carotenoid) was a complex substance in which little information was known, apart from its structural formula. An alternativeprocedure is to apply activity coefficient expression of the regular solution equations for each phase.Calculations along these lines are described and the physical basis for applying these methods underthe relevant conditions was also presented. The regular solution theory approach in particular hasbeen found to be encouraging for the mutual miscibility calculations for heavy components (such ascarotenoid) particularly substances that are sensitive to temperature, though the interaction parametersfor the prediction activity coefficients must be regarded as pressure dependent.

Keywords:

Activity coefficient , Carotenoid , Equation of state , prediction , Regular Solution Theory , Solubility