Excess molar volumes and excess molar enthalpies of binary and ternary mixtures of 1-butanol, a tertiary amine (tri-n-butylamine or tri-n-octylamine) and n-hexane: Experimental results and ERAS-model calculations

Experimental data at T = 298.15 K and ambient pressure of excess molar volumes VmE and excess molar enthalpies HmE are reported for two ternary and the corresponding binary mixtures of {1-butanol, tri-n-butylamine (TBA), or tri-n-octylamine (TOA), and n  -hexane}. A vibrating-tube densitometer was used to determine VmE. HmE was measured using a quasi-isothermal flow calorimeter. The experimental results are used to test the applicability of the ERAS model for describing both thermodynamic excess properties of ternary mixtures containing an alkanol, a tertiary amine and an n-alkane. Qualitative agreement of calculated values with experimental results was achieved using only system-specific parameters determined from binary mixtures. The results are explained in terms of the self-association between alkanol molecules, cross-association between the alkanol and the tertiary amines and structural effects.