Theoretical and experimental study of triethanolamine and 1-alkanol mixtures

Thermophysical properties as density and dynamic viscosity, and derivated properties as excess volume and deviation in viscosity were measured for four binary mixtures composed by trietanolamine + alkanol (1-propanol, 1-butanol, 1-pentanol, and 1-hexanol). The measurements were carried out in the entire mole fraction range of the liquid phase, at a pressure of 0.1 MPa, and at four temperatures (293.15 K, 303.15 K, 313.15 K, and 323.15 K). The perturbed chain-statistical associating fluid theory equation of state (PC-SAFT EoS) and the cubic plus association equation of state (CPA EoS) correctly modeled the density of binary mixtures. The free volume theory (FVT) combined with the equations of state was able to qualitatively determine the dynamic viscosity of all the mixtures. The experimental results of excess volume and viscosity deviation were successfully correlated with the Redlich–Kister equation. Finally, strong attractive forces are obtained for triethanolamine with 1-propanol or 1-butanol, and weak for triethanolamine with 1-pentanol or 1-hexanol. In addition, we have obtained a compression effect when mixing triethanolamine with 1-propanol or 1-butanol, and an expansion effect when mixing triethanolamine with 1-pentanol or 1-hexanol.