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

• Author / Creator

  Afshar, Shima

• 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.

• Subjects / Keywords

  • Solvent extractions
  • Contact angle
  • Naphthenic acids
  • Microemulsions
  • Oil Sands
  • Interfacial tension
  • Bitumen
  • Micropipette technique

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R36T0H45D

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.