Bitumen-Silica Interactions in a Deep Eutectic Ionic Liquid Analogue

In previous work, it has been shown that a deep eutectic mixture (DEM) of choline chloride and urea facilitates the detachment of bitumen from oil sands. To probe the mechanism underlying this observation, adhesive forces at the surface of the bitumen samples in deionized water and this DEM are compared using atomic force microscopy. PeakForce Tapping mode was used for force-distance measurement. Silicon nitride tips with dimensions of the order of 20 nm and silica colloidal particle attached probes with diameters of the order of 40 mu m were used. For both AFM probes, the adhesion force between the probe tip and the bitumen surface decreased significantly with increasing DEM concentration, as did the dissipation energy.