Separation of binary mixtures with the Cyrene solvent: Experimental activity coefficients at infinite dilutions

In this study, activity coefficients at infinite dilution ( γ 13 ∞ ) were measured for 31 selected organic solutes and water in dihydrolevoglucosenone (Cyrene) using the gas–liquid chromatography (GLC) technique, at 10 K intervals over the temperature range of 303.15 to 333.15 K ( p = 101.2 kPa). The obtained γ 13 ∞ data were used to compute the partial molar excess enthalpies ( Δ H i E , ∞ ), entropies ( T ref Δ S i E , ∞ ) and Gibbs free energies ( Δ G i E , ∞ ) at infinite dilution. These partial excess thermodynamic properties were further used to interpret and discuss the nature of solute–solvent molecular interactions, the influence of enthalpic contribution, and the spontaneity of mixing. Furthermore, the γ 13 ∞ data were used to calculate the selectivity ( S ij ∞ ) and capacity ( k j ∞ ) at infinite dilution- key separation parameters for examining the solvent's potential in separating industrially relevant binary mixtures, particularly those with close boiling points or azeotropic behaviour. The calculated values of S ij ∞ and k j ∞ were compared with those of other green solvents reported in the literature for mixtures such as n -hexane/thiophene or pyridine, n -heptane/toluene or ethanol, and cyclohexane/ethanol. Cyrene demonstrated promising performance as a green solvent for industrial separation processes, as supported by its favourable S ij ∞ and k j ∞ in these binary mixtures. • Physicochemical properties of the investigated solvent are presented. • GLC measured activity coefficients at infinite dilution in Cyrene. • The excess thermodynamic functions, entropies, and Gibbs energies were calculated. • The gas-liquid partition coefficients of the solutes were calculated. • Cyrene has the potential for desulfurization and denitrification.