Characterization of the Solvent Properties of Glycerol Using Inverse Gas Chromatography and Solubility Parameters

Abstract

AbstractThe production of glycerol from the synthesis of biodiesel has led to a market surplus of this polyhydric alcohol and additional research to find new applications for this versatile chemical. This study involves the use of inverse gas chromatography (IGC) to characterize the solute–solvent interactions between glycerol and a homologous series of aliphatic alcohols, in which the latter components are at infinite dilution in the glycerol, which is the stationary phase contained in a packed GC column. The IGC experiments were conducted between 51.5 and 111 °C for the n‐alcohols ranging from methanol to n‐butanol. All of the n‐alcohol homologs exhibited positive deviations from Raoult's law as based on mole fraction activity coefficients values ranging from 1.86 to 14.4. The measured mole fraction activity coefficients of the alcoholic solutes in glycerol showed good agreement with literature values, and in some cases with those predicted using existing theoretical models. The mole fraction activity coefficients increased going from methanol to n‐butanol, reflecting the change in the alcohol's cohesive energy densities relative to that for glycerol. The total solubility parameter of glycerol calculated from IGC data was found to be 34.8 MPa1/2 which is in good agreement with that obtained using Hansen solubility parameter approach (31.6 MPa1/2). This data can be used to characterize the solvent properties of glycerol as well as to provide thermodynamic data for the removal of the alcoholic solutes from glycerol.