Studies on the density, heat capacity, surface tension and infinite dilution diffusion with the ionic liquids [C 4mim][NTf 2], [C 4mim][dca], [C 2mim][EtOSO 3] and [ Aliquat][dca

Abstract

Ionic liquids are a class of fluids that requires the attentions of experimentalist and theoreticians. In a new project on synthesis and characterization of new and not-so-new ionic liquids, the study of several thermophysical properties of these liquids was started, namely binary diffusion, electrical conductivity, heat capacity, surface tension, viscosity and thermal conductivity. Among others we will study 1- n-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, ([C 4mim][NTf 2]), 1- n-butyl-3-methyl-imidazolium dicyanamide, ([C 4mim][dca]), 1-ethyl-3-methyl-imidazolium ethylsulfate, ([C 2mim][EtOSO 3]) and methyltrialkylammonium dicyanamide [Aliquat ®336-derived][dca], and in the case of diffusion, their mixtures with water. It is the purpose of this paper to report data on the density, using vibrating tube densimetry, infinite dilution diffusion coefficients, using the Taylor dispersion method, heat capacity, using DSC equipment and surface tension, using the Wilhelmy plate method. Density measurements were performed at atmospheric pressure between 293 and 363 K and several isotherms, depending on the stability of the compound, up to 60 MPa, with an uncertainty of 0.4%. Measurements were performed at 298.03 K for the infinite dilution measurements, with an uncertainty of 1.3–3.5%, for temperatures between 300 and 370 K for heat capacity, with an uncertainty better than 1.5%, and between 292 and 395 K for surface tension, with an uncertainty of 1.5–1.8%. A brief analysis of the potential of the fluids studied as engineering heat transfer fluids, namely its heat storage capacity was also performed.