Rate of Bitumen Film Transfer from a Quartz Surface to an Air Bubble as Observed by Optical Microscopy
The rate of bitumen transfer from a bitumen-coated quartz plate to a gas bubble surface in aqueous alkaline solutions was recorded photographically. During bitumen spreading, a bulk layer followed the formation of thin bitumen films (precursor films). The bulk layer spread at the bubble surface with a velocity of about one order of magnitude less than the velocity of the precursor film. The energy of activation for spreading of the bulk layer varied from about 66 to 123 kJ/mol depending on the stage of bitumen spreading but remained constant at about 105 kJ/mol for the precursor film. Results are discussed with respect to fundamental issues associated with flo t a t i o n r e c o v e ry of heavy oils.
Fractionation and characterization of Whiterocks Tar sands bitumen
Tar sand samples from the Whiterocks deposit, located in the Uinta basin in Utah, were obtained from three different locations. Bitumen separation from each of these samples was accomplished by the Dean-Stark toluene extraction method and the physical and chemical properties of the resulting bitumens were determined. Further, each bitumen sample was fractionated by the modified Saturates, Aromatics, Resins, and Asphaltenes method, and the separated fractions from one of the bitumens were characterized by Fourier transform infrared transmission and specular reflectance techniques
Flocculation and adsorption properties of cationic polyelectrolytes toward Na-montmorillonite dilute suspensions
Abstract Adsorption and flocculation properties were examined for the system Na-morillonite copolymers of acrylamide with a cationic monomer. Adsorption isotherms underlined the high affinity of the highly charged polymers for the clay surface and showed the crucial role of the interfacial conformation of the polyelectrolyte according to its cationicity. Performances of these copolymers when used as flocculants were followed as a function of their ionicity and molecular weight. The results are consistent with a balance between two flocculation mechanisms: charge neutralization which prevails for highly charged polymers and interparticular bridging which occurs at low cationicity when the optimal flocculation concentration (ofc) is strongly molecular weight dependent.