(660c) Investigation of the Spontaneous Emulsification Phenomenon in the Presence of Asphaltenes Using Microfluidics

Asphaltenes are complex polar components of heavy oils and are only marginally stable in organic solvents. Because of this marginal solubility, they have a propensity to adsorb onto oil/water interfaces to form viscoelastic layers. In addition, the contact of water against a solution of asphaltenes dissolved in a model hydrocarbon (such as toluene) induces a spontaneous emulsification phenomenon where micron-size water droplets, stabilized by asphaltenes, spontaneously appear. These can result in a strong stabilization of water-in-oil emulsions that cause difficulties in refining operations. In this work, we examine the spontaneous emulsification phenomenon in the presence of asphaltenes. First, the evolution of an oil/water interface and the spontaneous appearance of micron-size droplets are observed using a confocal microscope. Then, a microfluidic device is used to monitor the development of the spontaneous emulsification phenomenon at the surface of a single water drop in oil. The asphaltene concentration in solution, the solvents ratio (toluene and heptane are used) and the drop size are varied. Finally, we examine the influence of the proximity of other water drops on the spatial distribution of the spontaneously emulsified droplets at a water drop interface. We find that the drop size has a strong effect on spontaneous emulsification dynamics. Moreover, results indicate that the spontaneous emulsification at a water drop interface may be affected by the presence of a second drop.