Thermophysical properties of 1-Hexyl-3-methylimidazolium nitrate and 2-alkanol; measurement and modeling

Abstract

For binary systems containing 1-Hexyl-3-methylimidazolium nitrate ([Hmim][NO3]) ionic liquid and a homolog series of 2-alkanols, new data of density and viscosity at different temperatures and atmospheric pressure have been reported. Temperature range is 293.15–323.15 K, and the considered alcohols are 2-propanol, 2-butanol, and 2-pentanol. Regarding these data, values of thermal expansion coefficient, α excess thermal expansion coefficient, αE excess molar volume, VmE and deviation in viscosity, Δη were calculated. Both excess molar volumes and viscosity deviations are negative over the whole concentration range. The magnitude and type of interactions were interpreted versus the temperature and increase of carbon atom of alcohols. Findings show that strong interactions in the mixtures occur relative to the pure state, and intermolecular forces are weaker in the long-chain alcohols. For correlation and prediction of systems density, the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) was applied and results obtained from this theory are consistent with experimental data. Outcome densities from this theory were implemented for free volume theory to correlate the binary viscosities. Results are satisfactory with the maximum of 1.75% deviation from experimental viscosities. The whole data reported for binary systems are novel, and so far no reports have been investigated in scientific papers.