Vapour-liquid interfacial tension of water + methanol mixture from molecular dynamics simulation

Mixtures of water with alcohols play a fundamental role in many engineering applications, including chemical, petrochemical, and environmental engineering. In addition, surface tension is an interfacial property of great... [ view full abstract ]

Mixtures of water with alcohols play a fundamental role in many engineering applications, including chemical, petrochemical, and environmental engineering. In addition, surface tension is an interfacial property of great importance for mass transfer such as distillation, extraction, or absorption. Molecular simulation can be applied for calculating the interfacial tension, as well other interfacial properties, such as density profiles, interfacial thickness, and many other structural properties that allow to understand from a microscopic point of view the molecular mechanics that characterise the highly structured liquid formed from the mixture of water and alcohols. In this work we consider the simplest aqueous mixture with alcohols, namely, water + methanol mixture, and determine the interfacial properties from computer simulation. Water is modelled using the well-known TIP4P/2005 model and methanol with the OPLS/2006 model proposed recently by González-Salgado and Vega which is based on the classical OPLS model of Jorgensen. We perform molecular dynamic simulations in the NVT canonical ensemble to determine the most important vapour-liquid interfacial properties at several pressures, including surface tension, as well as the vapour-liquid coexistence phase behaviour. We also determine the phase behaviour with the SAFT-VR theoretical approach. Computer simulation results are compared with theoretical predictions and experimental data taken from the literature. Agreement between simulation, theory, and experiments are discussed in this contribution.