Colloid Science of Sand Remediation: A Study Motivated by the Non-Aqueous Extraction of Bitumen from Oil Sands

• Main Author: Afshar, Shima
• Other Authors: Yeung, Anthony (Chemical and Materials Engineering), Raghavan, Srinivasa R. (Chemical and Biomolecular Engineering, University of Maryland), Choi, Phillip (Chemical and Materials Engineering, University of Alberta), Liu, Qi (Chemical and Materials Engineering, University of Alberta), Nazemifard, Neda (Chemical and Materials Engineering, University of Alberta)
• Format: Thesis
• Language: English
• Published: University of Alberta. Department of Chemical and Materials Engineering. 2014
• Subjects: geo; envir; Athabasca River
• Online Access: http://hdl.handle.net/10402/era.39356

Specialization: Chemical Engineering Degree: Doctor of Philosophy Abstract: The current water-based method of bitumen extraction requires withdrawal of fresh water from the Athabasca River — a practice which leads to the continual buildup of tailings ponds and other environmental concerns. As Alberta’s bitumen production is expected to more than double by 2020, there is now a real need to explore the possibility of an alternative non-aqueous (or solvent-based) extraction technology. The main challenge that any non-aqueous extraction method faces is the recovery of residual oil from oil-laden sand grains. In this research, we propose a possible solution of washing the sand grains with aqueous surfactant solutions. From an interfacial science perspective, for a surfactant to give good residual oil recovery, it must create low oil-water interfacial tensions (IFTs) and desirable wetting characteristics. For this part of the investigation, the challenge was to accurately determine low IFTs and contact angles on the microscale (characteristic of the pore sizes); novel micropipette techniques were developed for this purpose. Of the different surfactants we had examined, natural surfactants extracted from bitumen, which appeared to be essentially sodium naphthenates, yielded the lowest IFT (down to 0.6 mN/m) and exhibited the most desirable (i.e. hydrophilic) wetting properties. On the macroscopic scale, the overall washing efficiencies of sodium naphthenates were also quantified. The efficiencies showed very different behaviors when the system was agitated under low or high shear rate. It is proposed that this discrepancy was due to the formation of thermodynamically stable microemulsions (a third phase) in the presence of surfactants.