A COMPREHENSIVE THERMODYNAMIC INVESTIGATION OF WATER ETHANOLAMINE MIXTURES AT 10-DEGREES-C, 25-DEGREES-C, AND 40-DEGREES-C

The density, isobaric specific heat capacity, and isentropic compressibility of water-ethanolamine (W-EA) mixtures have been measured at three temperatures (10, 25, and 40-degrees-C) over the entire composition range. The results were used to calculate various thermodynamic excess functions of these mixtures, namely: the excess molar volume (V(m)E), excess molar isentropic and isothermal compressibilities (kappa(S,m)E, kappa(T,m)E), excess molar isobaric and isochoric heat capacities (C(p,m)E, C(V,m)E), and excess molar isobaric expansion (partial derivative V(m)E/partial derivative T)p. The corresponding partial molar quantities for ethanolamine in the mixtures were also computed. These excess and partial molar quantities were compared with those observed earlier in the water - ethylene glycol (W-EG) (1) and in the water-2-methoxyethanol (W-ME) (2) mixtures. The similarities and differences in the properties of these systems are interpreted on the basis of the specific molecular features of the cosolvents and the concepts of cooperative fluctuations and hydrogen-bonding connectivity in liquid water and dilute aqueous solutions.