A solvent-free lecithin-Tween 80 system for oil dispersion

Phospholipids have been extensively used to disperse oil-in-water (O/W) as emulsions in the food and pharmaceutical industries. In this work a new strategy of dispersing oil and forming O/W emulsions in synthetic seawater is described using lecithin-Tween 80 (LT) self-assemblies (vesicles and disk-like micelles). LT assemblies can emulsify gasoline or crude oil with greater than 90% emulsion (or dispersion) efficiency at a total surfactant concentration that allows for complete coverage of the oil droplet interface. Comparing the experimental results with theoretical results based on geometric surfactant packing indicates that lecithin and Tween 80 monolayers pack tightly at the oil/water interface. When compared to lecithin or Tween 80 assemblies, the mixed LT assemblies provide better emulsion stability than lecithin and comparable emulsion stability to Tween 80, suggesting that steric stabilization provided by Tween 80 was the primary stabilization mechanism. Aqueous dispersants such as the LT assemblies can be prepared on demand and may prove effective for dispersing oil phases under conditions of high mixing energy.