Removal of emulsified water is a challenge in oil sands and heavy oil processing. The flocculation and coagulation of emulsified water droplets depend on the interactions between the water droplets covered mainly by asphaltenes and oil-contaminated fine solids. To quantitatively evaluate the stability of water-in-diluted bitumen emulsions, this research determined the interactions between asphaltene surfaces in model oils, heptane, toluene or a mixture of the two known as heptol, by colloidal force measurements using atomic force microscopy (AFM) in combination with the Langmuir-Blodgett technique. The effect of aromaticity of the solvents, temperature and water content of the solvents on asphaltenes-asphaltenes interactions was systematically investigated. The results showed that the interaction forces between asphaltenes are highly sensitive to the aromaticity of the organic solvents. In solvents of higher aromaticity, a repulsive force existed between asphaltene surfaces; whereas in solvents of lower aromaticity, a weak attraction was detected. The transition from repulsion to attraction indicates that it is possible to control asphaltenes-asphaltenes interactions, and ultimately to control the stability of asphaltene-stabilized water droplets in oil, through tuning the aromaticity of the organic solvents. By fitting the measured force profiles with theoretical models, the nature of the forces was determined, which provides insights into the mechanisms of asphaltene-stabilized water-in-oil emulsions. The concomitant benefit of the results from the direct force measurement is to predict asphaltene precipitation with change of solvent composition. Oil-contaminated fine solids not only help stabilize water-in-diluted bitumen emulsions but are detrimental to bitumen upgrading. To control the wettability of these fine solids, a preliminary study was carried out in this work to explore the potential of ethyl cellulose (EC), an effective demulsifier for water-in-diluted bitumen emulsion, as a surface wettability modifier of the oil-contaminated solids. It was found that EC is able to reduce the surface hydrophobicity of the asphaltene- and bitumen-contaminated solids and thus enhances their removal from bitumen froth. The mechanism of increased wettability by EC addition was determined by quartz crystal microbalance with dissipation (QCM-D) and AFM topographical imaging. The results from this study can help establish the criteria for selecting and developing chemical modifiers for applications in wettability control of oil-contaminated solids. / Chemical Engineering

Thesis (SC. D.)--University of Michigan, 1938. / Without thesis note. Photoprinted. Slip with substitute for paragraph 2, p. 22, inserted between p. 22 and 23. "Authorized reprint from the copyrighted Proceedings of the technical sessions of the Association of Asphalt Paving technologists, held at Memphis, Tennessee, December, 1937." "Literature cited": p. 56-57.

The ability of asphalt binders (bitumen) in road surfaces to self-heal after cracking is important to developing a robust transportation system that can tolerate heavy traffic and varying weather conditions. In order to develop improved binders, there is a need for noninvasive, in-situ, interface-specific methods of monitoring the kinetics, physics and chemistry of self-healing bitumen interfaces. Here the feasibility of using optical second-harmonic generation (SHG) by focused femtosecond laser pulses to monitor bitumen surfaces is demonstrated. SHG signals are observed in transmission through a sample composed of bitumen spin-coated onto a borosilicate microscope coverslip. The SHG signals are absent from uncoated coverslips, demonstrating that they originate from the bitumen layer. Further tests demonstrate that the bitumen-air surface makes the dominant contribution to the SHG signal. The SHG signal is observed to decay on a time scale comparable to typical self-healing times because of sample heating by the incident laser irradiation. Methods to control this effect by translating the sample during data acquisition are developed. Although the present results were obtained with a single incident wavelength (800 nm), they demonstrate the feasibility of probing bitumen interfaces spectroscopically with tunable light sources in order to monitor bond-specific chemical kinetics. / text

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The extraction of bitumen (heavy oil) from the oil sands is predominantly achieved through a water-based technology. This involves a slurrying process, typically called conditioning, which is categorized into three equally important steps: bitumen-sand liberation, bitumen coalescence, and air-bitumen attachment. Previous studies found that bitumen recovery was dependent upon process variables such as energy dissipation rate, temperature and caustic addition. Correlations between bitumen droplet size and recovery have also been established; however no investigations linking the aforementioned process variables to the resultant bitumen droplet size had been performed. This work investigates the development of a Batch Extraction Unit built specifically for this investigation as well as a study of the bitumen droplet size as a function of the rate of mechanical energy input. / Chemical Engineering