The Effect of Switchable Additives on Colloidal Interactions Found in Oil Sands

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Lau, Ying Yin
This thesis describes an investigation of how carbon dioxide triggered switchable additives affect colloidal interactions found in oil sands, in an effort to identify potential candidates for industrial use. Chemical force spectrometry was used to evaluate adhesion forces present in model oil sand systems. Organic/mineral and mineral/mineral interactions were investigated in the presence of cationic and anionic switchable surfactants, as well as switchable ionic strength additives. Of the additives studied, cationic switchable surfactants caused the greatest change in adhesion force between solutions free of CO2 and solutions saturated with CO2. These trends were consistent across all of the systems examined. The effect of switchable additives on clay suspension behavior was studied by zeta potential measurements. The stability of clay suspensions are a problem in tailings disposal because fine mineral matter in recycled process water are detrimental to bitumen extraction. Cationic and anionic switchable surfactants were investigated, as were switchable ionic strength additives. Switchable ionic strength additives demonstrated the ability to suppress clay zeta potential to nearly zero upon exposure to CO2. It was demonstrated that destabilization of clay suspensions can be achieved upon exposure of aqueous solutions containing the additives to CO2.
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