Amin Reza Zolghadr*, Mohammad Hadi Ghatee, and Ali Zolghadr
J. Phys. Chem. C, 2014, 118 (34), pp 19889–19903
Publication Date (Web): August 4, 2014 (Article)
Molecular dynamics simulation of heptane/ionic-liquid/water system was performed to study the effect of hydrophobic and hydrophilic ionic liquids (ILs) on the interfacial structure of heptane/water as a model for oil/water systems. The results are compared with the simulated water/sodium-dodecyl-sulfate (SDS)/heptane interface. Also, the self-assembly and orientation of ILs and SDS molecules at heptane/vapor interface are studied. We observed that the behavior of these surfactants at heptane/water and heptane/vapor interfaces is very different. The computed density profiles provide a detailed view of the interfacial structure and a route to discuss quantitatively how the oil and water phases organize the surfactant molecules. The effect of ILs [Cnmim]Cl and [Cnmim]PF6 (with n =4, 8, and 12) and SDS on the interfacial tension of heptane/water was simulated and compared at T = 343.15 K. The results indicate that ILs with long alkyl chain could behave similar to a conventional surfactant.