Adsorption Equilibria of <i>cis</i>-5,8,11,14,17-Eicosapentaenoic Acid Ethyl Ester and <i>cis</i>-4,7,10,13,16,19-Docosahexaenoic Acid Ethyl Ester from Supercritical Carbon Dioxide on Silica Gel

Abstract

Adsorption data of cis-5,8,11,14,17-eicosapentaenoic acid ethyl ester (EPA-EE) and cis-4,7,10,13,16,19-docosahexaenoic acid ethyl ester (DHA-EE) from supercritical carbon dioxide on silica gel were determined at temperatures from (319.15 to 340.35) K and carbon dioxide densities from (0.668 to 0.734) g·mL−1 by using the elution by characteristic point (ECP) method. The equilibrium isotherm data were fitted using a Langmuir model. The monolayer adsorption capacity of EPA-EE is 0.130 mmol·g−1, and that of DHA-EE is 0.119 mmol·g−1. The adsorption enthalpy change of EPA-EE is in the range of (34.4 to 38.0) kJ·mol−1, and that of DHA-EE is in the range of (34.4 to 40.6) kJ·mol−1.