The role of naphthenates and kaolinite in toluene and toluene-bitumen emulsions

The study of toluene emulsions is relevant to understand the behavior, and the separation of solvent-diluted bitumen emulsions. Previous studies of similar systems have revealed that the presence of naphthenates, particles - specifically kaolinite- and asphaltenes can play an important role in the formation and stability of solvent-diluted bitumen emulsions. The objective of this work was to elucidate the relative importance of these factors. It was determined that in bitumen-free systems the presence of sodium naphthenates facilitates the entrapment of kaolinite in the emulsion and its segregation at the oil-water interface, which contributes to stabilize the emulsions. However, bitumen components (asphaltenes, resins, and other components) were shown to be more interfacially active than naphthenate-adsorbed kaolinite, resulting in the rejection of kaolinite from the emulsion. In naphthenate-adsorbed kaolinite emulsions, the presence of bitumen components is the dominant factor in determining the level of particles and water entrapped in the emulsion. Bitumen-coated kaolinite emulsions behaved in the same way as bitumen-free systems, suggesting that as long as the particle is pre-adsorbed with the dominant surface active species, particles can contribute to stabilize emulsions.