Measurement and Modeling of Thermophysical Properties of the Ternary System 2-(Butylamino)ethanol + Dimethyl Sulfoxide + Water and Its Binary Subsystems

Density and viscosity data of the ternary system containing 2-(butylamino)ethanol (BAE), dimethyl sulfoxide (DMSO), and water and its corresponding binary systems were measured at atmospheric pressure and in a temperature range of 293.15–353.15 K. The excess molar volumes (V^E), viscosity deviations (Δη), and excess free energies of activation (ΔG^*E) of binary subsystems were calculated at all temperatures and associated with the Redlich–Kister equation, while the excess properties of the ternary system were correlated with the Nagata–Tamura equation. Under the investigated composition range and temperature conditions, the V^E values are negative and the values of Δη and ΔG^*E are positive for the binary mixtures DMSO + H₂O and BAE + H₂O. However, opposite signs were observed for the nonaqueous binary system BAE + DMSO. The sign and magnitude of excess/deviation properties were discussed and interpreted with intermolecular interactions and structural effects. The V₁₂₃^E values of the ternary system in the water-rich regions are generally negative while show positive in the regions that are extremely poor in water. Δη₁₂₃ values become more and more positive in the region with abundant BAE and H₂O but extremely poor in DMSO. In addition, as the temperature increases, the absolute values of Δη₁₂₃ become smaller. These excess features of the ternary system can be explained by the dominant binary effects.