Water-in-oil emulsion separation within a milli-fluidic device

Area of Science:

• Chemical Engineering
• Materials Science
• Fluid Dynamics

Background:

• Water-in-oil emulsions are prevalent in various industries but challenging to separate.
• Existing separation methods can be energy-intensive or inefficient.
• Milli-fluidic systems offer potential for precise and scalable separation processes.

Purpose of the Study:

• To develop a continuous passive milli-fluidic method for water-in-oil emulsion separation.
• To investigate the use of disparate channel wall hydrophobicity for emulsion separation.
• To demonstrate the efficiency and advantages of milli-fluidic emulsion separation.

Main Methods:

• A milli-fluidic device with opposing channel walls of differing hydrophobicity was designed.
• One channel wall was functionalized with a hydrogel (polyethylene glycol).
• High oleic sunflower oil or mineral oil served as the continuous phase, with aqueous solutions as the dispersed phase.

Main Results:

• The device achieved continuous passive separation of water-in-oil emulsions with approximately 90% efficiency.
• Stable cocurrent laminar flow of oil and water was maintained by the hydrophobic/hydrophilic channel walls.
• Emulsion separation was effectively initiated at the water/hydrogel interface.

Conclusions:

• The developed milli-fluidic method provides an efficient and passive approach for water-in-oil emulsion separation.
• The use of disparate channel wall hydrophobicity is a key factor in achieving stable flow and separation.
• Milli-fluidic scale separations offer distinct advantages for emulsion processing.