Modeling the Excess Molar Volumes of Six (Monoethanolamine+Alcohol) Mixtures: The influence of Equation of State, Association Scheme and Cross Association Energy on the Accuracy of the Estimations

Abstract

In this study, the Cubic Plus Association (CPA) and Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state were applied to describing the excess molar volumes of binary mixtures of monoethanolamine with six alcohols, including ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 1-pentanol. The 2B association scheme was considered for all alcohols. Three association schemes of monoethanolamine, namely 2B, 3B, and 4C, together with two strategies for determining the cross-association energy, were applied to these six binary systems. The first strategy employed conventional combining rules, whereas the second strategy estimated the cross-association energy by fitting it to the experimental excess molar volume data of the investigated mixtures. The results show that the combination of the PC-SAFT equation of state, the second strategy, and the 4C association scheme of monoethanolamine is the most accurate approach, with average absolute deviation percentages in the range of (2.88–6.30)%. Furthermore, the PC-SAFT EoS was found to be significantly more sensitive to the cross-association energy than the CPA EoS.