Acoustic and electroacoustic spectroscopy of water-in-diluted-bitumen emulsions.

Water-in-oil emulsions of Athabasca bitumen diluted with toluene have been studied using the latest advances in acoustic and electroacoustic spectroscopy. From the sound attenuation spectra of emulsions, the water droplet size distribution is measured. The electrical surface charge density of the water droplets is obtained from the colloid vibration current. In the case of freshly prepared water-in-oil emulsions, the droplet size increased while the surface charge density decreased with time. The time-dependent relaxation of the surface charge ranges from several hours to 3 days, and it is probably due to the slow adsorption/desorption kinetics of bituminous components at the water-oil interface. This study illuminates the contribution of the electrostatic interactions to the stability of water-in-oil emulsions.