Volumetric, acoustic, and refractometric properties of (thiophene + hexane/cyclohexane) solutions in the presence of some imidazolium based ionic liquids at T = 298.15 K

• The density, speed of sound and refractive index of (ionic liquid + thiophene + hydrocarbon) have been measured.
• Using the measured data, the solute–solvent interactions have been calculated.
• The results indicate that thiophene–[HMIM]Br interactions are strong rather than other ionic liquid.
• The scaled particle theory (SPT) was used to interpretation of volumetric results.

Effective extraction of sulfur aromatic containing compounds from fuels by use of ionic liquids needs the knowledge and precise measurements of thermodynamic properties. In this work, effect of two types of the ionic liquids, 1-hexyl-3-methylimidazolium bromide [HMIM]Br, and 1-ethyl-3-methylimidazolium ethyl sulfate [EMIM]EtSO4 on the thermodynamic properties of thiophene in hexane or cyclohexane solutions have been investigated. In this way, the densities, speeds of sound, and refractive indices of the solutions being studied have been measured at T = 298.15 K. These data have been used to calculate standard partial molar volumes Vϕ0, transfer partial molar volumes ΔtrVϕ0, partial molar isentropic compressibility κφ0, and molar refractions RDRD. The calculated parameters were used to discuss the manner of ionic liquid–thiophene interactions. Also, the scaled particle theory (SPT) was used to confirm and deep insight of results obtained from the calculated volumetric properties in terms of interaction volume VintVint, and cavity volume VcavVcav.