Mechanistic Understanding of the Effect of Temperature and Salinity on the Water/Toluene Interfacial Tension

In this work, a series of pendant drop measurements and molecular dynamics (MD) simulations were performed to investigate the effects of temperature and salinity on the interfacial tension (IFT) of water/toluene binary systems. Both experimental measurements and theoretical simulations demonstrated that elevating temperature decreased the IFT, while adding salts resulted in an increment of IFT. Furthermore, it was found that the presence of model asphaltene compound could alleviate the effects of temperature and salinity on the IFTs. That is, in the presence of the model asphaltene compound, the decrement effect of elevating temperature as well as the increment effect of adding salts was reduced. Through detailed analysis of the simulated systems, the underlying mechanisms for the effects of temperature and salinity on the IFTs were clarified for cases with and without the presence of the model asphaltene. The results reported here can help to modulate the IFT values of oil/water interfaces in petroleum processing.