Interfacial behavior prediction of alcohol + glycerol mixtures using gradient theory

This work has been dedicated to modeling the interfacial tension and interfacial density profiles of alcohol + glycerol mixtures in the temperature range of 293.2 K–333.2 K. The Peng-Robinson equation of state and quadratic mixing rule is applied to the liquid - vapor phase equilibrium calculations. The binary interaction parameters are obtained according to the experimental phase equilibrium data at 1 atm. The gradient theory is used as a predictive approach to describe the interfacial behavior of alcohol + glycerol mixtures. The results of this study show that the equation of state used is capable of simultaneously representing the phase equilibrium and interfacial behavior of the mixtures studied. Despite using a simple equation of state, the results in phase equilibrium and interfacial tension are good. The main advantage of using the gradient theory is to obtain results on the accumulation and non-accumulation of the components at the interface, where the alcohols accumulated in the interfacial region, whereas glycerol does not show surface activity, except in the mixture with methanol.