Determination of Surface Characteristics of Epoxidized Soybean Oil by Inverse GC

Abstract

The dispersive free energy and acid–base forces of epoxidized soybean oil (ESO) were determined by inverse gas chromatography (IGC). Eight non-polar and polar solvents were used as the probes in the temperature range between 303.15 and 343.15 K. The IGC characterization encompassed the adsorption thermodynamic parameters, including the standard enthalpy ( $$ \Updelta H_{\text{a}}^{\text{s}} $$ ) and the free energy change of adsorption ( $$ \Updelta G_{\text{a}}^{\text{s}} $$ ), using the retention time of different non-polar and polar probes at the infinite dilution region. Surface characterization showed that ESO has low $$ r_{\text{s}}^{\text{d}} $$ value, even at 303.15 K, and is a Lewis amphoteric material with predominantly basic character, as confirmed by the Lewis acidity and basicity constants K a and K b, respectively.