Activity coefficients at infinite dilution of organic solutes in diethylene glycol and triethylene glycol from gas–liquid chromatography

Abstract

The infinite dilution activity coefficients for 25 hydrocarbon solutes in diethylene glycol (DEG) and triethylene glycol (TEG) were measured using the gas–liquid chromatography technique with pre-saturation of the carrier gas. The hydrocarbon solutes included n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alkanols. At the temperatures at which measurements were conducted, the solvents were volatile, and pre-saturation was considered necessary. The measurements were made at T=(333.2, 348.2 and 363.2)K. Values of the selectivity and capacity relating to DEG and TEG, for two sets of mixtures, which are usually difficult to separate by distillation or solvent extraction, were calculated from the experimental results. The two sets of mixtures were: cyclohexane and benzene; and benzene and methanol. The results obtained in this work were then compared to values for other solvents, at similar temperatures, which were obtained or calculated from literature data.