Binary Mixture of Double Protic Ionic Liquid: Density, Viscosity, Refractive Index, Surface Tension, and Derivative Properties

Abstract

This work presents density (ρ), dynamic viscosity (η), refractive index (nD), and surface tension (γ) experimental data for three pure protic ionic liquids: 2-hydroxyethylammonium acetate ([2-HEA][Ac]), bis(2-hydroxyethyl)ammonium acetate ([BHEA][Ac]), and bis(2 hydroxyethyl)ammonium butyric ([BHEA][Bu]), along with experimental data for two binary systems, as follows: ([2-HEA][Ac] + [BHEA][Ac]) and ([2-HEA][Ac] + [BHEA][Bu]), at a temperature range of T = 278.15 to 343.15 K and atmospheric pressure (101.3 kPa). For the ([2-HEA][Ac] + [BHEA][Ac]) binary system, excess volume and refractive index deviation values are negative, while for the ([2-HEA][Ac] + [BHEA][Bu]) binary system are positive. For the first, there is a volume contraction, with higher probability of ion interactions. For the latter system, an expansive trend and lower ion interactions were found when compared to the ([2-HEA][Ac] + [BHEA][Ac]) system. Viscosity deviations values show a negative behavior for both binary systems studied. These results could indicate the predominance of dispersive forces. Furthermore, for the [2-HEA][Ac] + [BHEA][Ac] system, surface tension deviation values are positive. On the other hand, for the [2-HEA][Ac] + [BHEA][Bu] system this derivative property are negative. From these results, the [2-HEA][Ac] + [BHEA][Ac] binary system could be characterized by presenting prevalent dispersion forces and an unequal distribution of the mixture components between the bulk and interface.