Dispersants were used extensively to emulsify crude oil during the Deepwater Horizon oil spill. In contrast to surfactant-stabilized emulsions, ones that are stabilized by interfacially active particles can remain stable at large background dilutions, and can also be used to absorb toxic polycyclic aromatic hydrocarbons and thus lower their concentration in the water.  We create particle stabilized octane-in-water emulsions by modifying the pH and/or varying the salt concentration of a carbon black suspension in water, adding octane to this suspension and vortex mixing.  Cryo-SEM images reveal that at 'high' carbon black concentrations in the aqueous phase, the particles arrange into multiple layers at the octane-water interfaces.  At 'low' concentrations, stable emulsions are created with sub-monolayer coverage.  We monitor the zeta potential of these carbon black particles at various pH and salt concentrations, and show that the hydrophilic/hydrophobic balance which determines particle positioning at the oil-water interface, is related to this potential.  Emulsion stability, quantified by measuring the critical de-emulsification pressure using centrifugation, is much higher for the CB stabilized emulsions than those stabilized using surfactants.  When napthalene, a model polycyclic aromatic hydrocarbon, is added to the octane, its partitioning into the aqueous phase is reduced dramatically from a control case with no carbon black.  We propose that these particles have potential use for emulsifying crude oil dispersions subsequent to an oil spill.

Oil emulsification using responsive carbon black particles

243rd National Meeting (2012)

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