Modeling Surface Tension of (Monoethanolamine+Water) Mixture: The Role of Equation of State, Association Scheme and Cross Association Energy

The gradient theory of the interface is combined with the cubic plus association and perturbed chain statistical association fluid theory equations of state to estimate the surface tension of (monoethanolamine + water) system for the first time. For each equation of state, three cases of association scheme and two forms of influence parameters have been used. Two forms of influence parameters are also applied to the gradient theory. The second form contains two exponents that lead to the accuracy of surface tension estimations, especially at low mole fractions of monoethanolamine. The highest and lowest AADs% of surface tension are 5.24 and 1.11, respectively. The interfacial density profiles show the enrichment of the surface layer with monoethanolamine. However, the enrichment of the surface layer does not exist at high concentrations of monoethanolamine in the mixture. The overall AADs% of the present model confirm its reliability for description of (monoethanolamine + water) interface.