Molecular Dynamics Study of Surfactant and Oil Interactions at Saltwater-Air Interfaces

For water treatment purposes, the separation processes involving surfactants and crude oil at seawater-air interfaces are of particular importance for chemical and energy industries. Although there is some experimental work in the area, little progress has been made in fundamentally understanding the nanoscale phenomena of surfactants on oily saltwater-air interfaces. Thus, we focus on using molecular dynamics to simulate the interface with various types of crude oil and surfactants. Preliminary results have shown that with an increasing surface excess of methyl isobutyl carbinol (MIBC) surfactant, there is a decrease in surface tension on an interface composed of the single point charge extended (SPC/E) water model. This is consistent with trends reported in literature and does not contradict the transferable potentials for phase equilibria (TraPPE) force field being utilized. Future work will include investigating other alcohols and glycol ether surfactants as well as light and heavy crude oil types represented by linear alkanes of different molecular weight. An experimental component will be included to assist in verifying model parameters and measurements. By measuring surface tension and characterizing the oil adsorption behavior, the project is aiming to predict surfactant performance for experimental testing under cold seawater conditions.