Dynamic and static interactions between bitumen droplets in water

Area of Science:

• Colloid and Surface Science
• Chemical Engineering
• Materials Science

Background:

• Bitumen extraction relies on controlling droplet interactions in water.
• Dynamic and static forces between bitumen droplets influence coalescence.
• Understanding these forces is crucial for optimizing extraction processes.

Purpose of the Study:

• To measure and compare dynamic and static interaction forces between bitumen droplets.
• To investigate the relationship between surface chain length and inter-droplet forces.
• To assess the implications of these forces on commercial bitumen extraction.

Main Methods:

• Colloidal particle scattering was used to measure dynamic droplet-droplet interactions.
• Hydrodynamic force balance techniques determined static attractive forces between droplets.
• Droplet-droplet collision trajectories and doublet separation forces were analyzed.

Main Results:

• Dynamic force measurements indicated the presence of rigid chains on bitumen surfaces, with mean lengths of 50 nm (deasphalted bitumen, pH 7), 78 nm (whole bitumen, pH 7), and 41 nm (whole bitumen, pH 8.5).
• Static force measurements revealed significantly shorter mean chain lengths (<9 nm) for all tested bitumen systems.
• Shorter static chain lengths correlate with weaker repulsive forces between bitumen droplets.

Conclusions:

• A significant discrepancy exists between dynamic and static measurements of bitumen surface chain lengths.
• Weaker static repulsive forces between bitumen droplets have critical implications for coalescence and process efficiency in commercial extraction.
• Further research into the nature of these surface forces is warranted to optimize bitumen recovery.