2 research outputs found
Biodiesel-Assisted Ambient Aqueous Bitumen Extraction (BA<sup>3</sup>BE) from Athabasca Oil Sands
The
water-based extraction process has been almost exclusively
used in the current industry for Athabasca oil sands extraction to
produce bitumen and heavy oil. However, the current method is facing
various challenges, primarily including high energy intensity, poor
processability with poor-quality ores, large consumption of fresh
water, and concerns on considerable volume of tailings. Although the
technology of using nonaqueous solvent as extraction medium has numerous
advantages, problems such as solvent loss to tailings and high capital/operating
costs are difficult to address. A biodiesel-assisted ambient aqueous
bitumen extraction (BA<sup>3</sup>BE) process has been herein proposed
as an alternative to water-based and solvent-based extraction processes.
The results showed a significant improvement in both froth quality
and bitumen recovery (increased from ∼10% to ∼80% with
biodiesel addition) for processing poor-quality ores at ambient temperature
(25 °C), which is much lower than the temperatures used in the
current industrial practice (40–55 °C). The aqueous tailings
generated in the BA<sup>3</sup>BE process were found to feature faster
settling and enhanced densification, which is favorable for recovering
processing water and improving land reclamation. Furthermore, the
innovative BA<sup>3</sup>BE extraction process requires similar facilities
and procedures as the current industrial processes, which can be considered
as an advantage for commercialization
Nanostructures in Water-in-CO<sub>2</sub> Microemulsions Stabilized by Double-Chain Fluorocarbon Solubilizers
High-pressure
small-angle neutron scattering (HP-SANS) studies
were conducted to investigate nanostructures and interfacial properties
of water-in-supercritical CO<sub>2</sub> (W/CO<sub>2</sub>) microemulsions
with double-fluorocarbon-tail anionic surfactants, having different
fluorocarbon chain lengths and linking groups (glutarate or succinate).
At constant pressure and temperature, the microemulsion aqueous cores
were found to swell with an increase in water-to-surfactant ratio, <i>W</i><sub>0</sub>, until their solubilizing capacities were
reached. Surfactants with fluorocarbon chain lengths of <i>n</i> = 4, 6, and 8 formed spherical reversed micelles in supercritical
CO<sub>2</sub> even at <i>W</i><sub>0</sub> over the solubilizing
powers as determined by phase behavior studies, suggesting formation
of Winsor-IV W/CO<sub>2</sub> microemulsions and then Winsor-II W/CO<sub>2</sub> microemulsions. On the other hand, a short C2 chain fluorocarbon
surfactant analogue displayed a transition from Winsor-IV microemulsions
to lamellar liquid crystals at <i>W</i><sub>0</sub> = 25.
Critical packing parameters and aggregation numbers were calculated
by using area per headgroup, shell thickness, the core/shell radii
determined from SANS data analysis: these parameters were used to
help understand differences in aggregation behavior and solubilizing
power in CO<sub>2</sub>. Increasing the microemulsion water loading
led the critical packing parameter to decrease to ∼1.3 and
the aggregation number to increase to >90. Although these parameters
were comparable between glutarate and succinate surfactants with the
same fluorocarbon chain, decreasing the fluorocarbon chain length <i>n</i> reduced the critical packing parameter. At the same time,
reducing chain length to 2 reduced negative interfacial curvature,
favoring planar structures, as demonstrated by generation of lamellar
liquid crystal phases