Role of Bitumen Components in Stabilizing Water-in-Diluted Oil Emulsions

Role of bitumen components in stabilization of water-in-diluted oil emulsions was studied using the micropipette technique. Naturally occurring components of bitumen, asphaltenes and maltenes were separated (by precipitating asphaltenes with n-pentane) to investigate their influence on the properties of water drop surfaces in Heptol (a mixture of heptane and toluene at a 4:1 volume ratio). The Heptol-water interfacial tension decreased with increasing adsorption of surface active components from both asphaltenes and maltenes. Rigidity of emulsified water droplet surfaces was observed in the presence of asphaltenes dissolved in Heptol. The observed surface crumpling is attributed to the irreversible adsorption of asphaltenes on the emulsified water droplet in Heptol. Further, the results of droplet interaction experiments indicated that the stability of the water-in-diluted oil emulsions was mainly due to the presence of asphaltenes dissolved in Heptol. However, it was observed that the presence of maltenes can also contribute to the emulsion stability even without well-defined skin formation on the emulsified water droplet surfaces.