Thermophysical properties of two binary aqueous mixtures containing a pyridinium-based ionic liquid

• A thermophysical study of aqueous mixtures containing ionic liquids was carried out.
• The pyridinium-based ionic liquids were [ppy][BF4] and [bpy][BF4].
• Properties have been determined at 99.0 kPa from 293.15 K to 323.15 K.
• Interactions IL–water weaker than those existing in the pure compounds were observed.

Densities, speeds of sound, refractive indices, surface tensions and kinematic viscosities for (1-propylpyridinium tetrafluoroborate or 1-butylpyridinium tetrafluoroborate + water) mixtures were determined at the temperatures: (293.15, 303.15, 313.15, and 323.15) K and at the pressure of 99.0 kPa. From the experimental data, several excess properties or property deviations have been obtained and correlated. These properties have been discussed taking into account structural and energetic factors; their values seem to indicate that interactions ionic liquids–water are weaker than those operating in the pure compounds.

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