Abstract

We have determined the pressure-density diagram and the surface tension of the tetrahydrofuran + methane (THF + CH4) binary mixture from experiments at 300.15 and 370.15 K and over the pressure range of 0.1-20 MPa. In addition to this, we have also obtained the phase equilibria and interfacial properties of the system from a molecular dynamics computer simulation. THF is modeled as a rigid and planar approximated TraPPE-UA model proposed by us in a previous work [Garrido, J. M. et al. J. Chem. Phys. 2016, 144, 787 144702-144711]. This model has been used recently to determine the vapor-liquid interfacial properties of the THF + carbon dioxide binary mixture [Algaba, J. et al. J. Chem. Phys. C 2018, 122, 16142-16153] with high accuracy. The simulations are performed using the direct coexistence technique in the molecular dynamics NVT canonical ensemble. We have determined density profiles, pressure-composition, pressure-density, and surface tension. The last property is calculated using the virial definition of the pressure tensor. Predictions of the phase equilibria are in good agreement with experiments. Predictions for surface tension obtained from simulations have also been compared with the experimental results, the agreement being excellent in all cases. The surface relative Gibbs adsorption of the species along the interfacial region is reported; methane is adsorbed along the interfacial region, whereas tetrahydrofuran does not exhibit any special adsorption activity. The adsorption of methane increases with pressure and decreases with temperature.