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The progress summarizes experimental tasks and results obtained to date:

1. Procurement of oil samples and reactor setup

Two Canadian oil sand samples and one Utah sample were obtained.  A Parr 5100 low pressure glass reactor was purchased and set up to conduct experiments.  The pressure-resisting, transparent reactor makes it possible to observe and record videos of microbubbles and its physical interactions with oil and sand in the liquid during the reaction process.

2. Contact of oil sands with hot water

Extraction of bitumen with hot water was conducted with Utah oil sands sample. It was found that it took over 3 hours at >85 ^oC with intense stirring agitation to dislodge and recover the bitumen in Utah oil sands; this is necessary even under favorable pH condition (e.g., pH > 11). In comparison, dislodging of bitumen in hot water (without pH adjustment) with pressure cycles was complete within 30 minutes.

3. Contact of oil sands in hot water with pressure cycles of air and CO₂

Extraction of bitumen from oil sands in hot water with pressure cycles of air and CO2 were conducted.  Different experimental parameters including the number of pressure cycles, solid loading, temperature, and pressure were employed to determine their effects on the dislodging and recovery of bitumen.  Air and CO₂ were used separately in the pressurized injection and the results compared.  

Experimental results with Utah oil sands show increasing bitumen extraction with increasing pressure cycles and that maximum extraction >90% was achieved by 4 to 5 pressure cycles.  Solid loadings affected bitumen recovery. Typically the volume ratio of water to oil sands needed to >2 to provide room for flotation of bitumen and generation of bitumen froth.  Figure 1 shows bitumen recovery (%) from Utah oil sands with different solid to water ratios.  A higher solid to volume ratio would represent increased energy efficiency with respect to energy expended in heating and pressurization per volume of oil sands processed; the results show that effective recovery (>90%) is attainable even at the very low solid to water ratio of 1.5:1. 

The temperature of the water/oil sands mixture was studied between 50 ^oC to 150 ^oC.  Bitumen recovery was strongly dependent on temperature.  Above 80 oC, separation of bitumen from oil sands was over 80%, while below 80 ^oC, separation was significantly incomplete (<30%).  
Bitumen recovery from Utah oil sands under different compression pressures revealed that higher compression pressure favored recovery, with ?90% recovery using 100 or 150 psi while <50% recovery at 50 psi.  

Overheated condition of the water occurred when it is prevented from boiling by pressurization at temperature exceeding the boiling point under atmospheric pressure. When the pressure is released for the overheated water, it boils spontaneously creating gas bubbles as well.  The expanding and shearing actions of the gas bubbles in boiling water on dislodging bitumen from oil sands were also studied.  These actions due to decomposition of overheated water were found to accelerate displacement of bitumen from the surface of oil sands. The coalescence and rising of small gaseous bubbles collected and floated the bitumen droplets to the water surface resulting in a bitumen froth. Results showed increased and more rapid (few pressure cycles) bitumen recovery under overheated condition. 

Increased bitumen recovery resulted when CO₂ was used as an injection gas. This was attributed to higher solubility of CO₂ in water as well as increased chemical compatibility of CO₂ with bitumen, an effect being examined more closely.  

4. Contact of pure bitumen coated on surface with hot water and pressure cycles of air or carbon dioxide

Bitumen was extracted from soil sands with DCM and then coated onto the reactor glass surface by evaporation of the solvent resulting in a thin layer of bitumen coat. The bitumen coat was subjected to hot water and pressure cycles of air and CO₂, respectively. The bitumen was readily released at temperature as lowa as 55 ^oC, and the release indicated no differences with or without the use of pressure cycles with air.  When pressure cycles with CO₂ were applied, gas bubbles were discernibly coated with bitumen at the gas-liquid interface. 

5. Characterization of chemicals in the process water

The water used in hot water extraction process with pressure cycles of air contained COD of 95±5 mg/L, while the water with pressure cycles of CO₂ contained COD of 47±3 mg/L (< 20 mg/L organic carbons).  This might be explained by the lowered solution pH in the CO₂-rich water that prevent the dissolution of ionizable organics.  In either case, the water contained far less process water of the conventional hot water extraction process that requires alkaline pH for the extraction process to be effective.