Probing the Interaction Mechanism between Air Bubbles and Bitumen Surfaces in Aqueous Media Using Bubble Probe Atomic...

Area of Science:

• Surface science
• Colloid and interface science
• Materials science

Background:

• Surface interactions involving deformable air bubbles are crucial in mineral flotation and bitumen extraction.
• Understanding these interactions is key to optimizing industrial processes.

Purpose of the Study:

• To directly measure interaction forces between air bubbles and bitumen surfaces in complex aqueous media.
• To investigate the influence of pH, salinity, and specific ions on bubble-bitumen attachment.

Main Methods:

• Utilized a bubble probe atomic force microscope (AFM) technique for direct force measurements.
• Employed AFM topographic imaging to analyze bitumen surface morphology.
• Applied a theoretical model combining Reynolds lubrication theory and augmented Young-Laplace equation with disjoining pressure.

Main Results:

• Bitumen surface roughness and domain formation increase with high NaCl concentration or alkaline conditions.
• Electrical double layer (EDL) repulsion inhibits attachment at low ionic strength (1 mM NaCl), intensified by higher pH.
• Hydrophobic attraction promotes attachment at high ionic strength (500 mM NaCl), weakened by high pH.
• Calcium ions enhance hydrophobic interaction and attachment, likely via bridging effects, increasing surface roughness.

Conclusions:

• Ionic strength and pH critically control bubble-bitumen interaction and attachment.
• A theoretical model accurately describes these interactions, incorporating disjoining pressure.
• Nanoscale insights into bubble-bitumen interactions have significant implications for oil production, separation, and wastewater treatment.