Related Experiment Videos
Surfactant adsorption and Marangoni flow in liquid jets. I. Experiments
Turgut Battal1, Colin D Bain, Michael Weiss
1Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford OX1 3QZ, UK.
Journal of Colloid and Interface Science
|June 14, 2003
Summary
Surfactant adsorption at expanding liquid surfaces was studied in a water jet. High expansion rates near the nozzle limit surfactant concentration, while downstream, Marangoni stress decelerates the surface.
Area of Science:
- Fluid Dynamics
- Surface Chemistry
- Colloid Science
Background:
- Understanding surfactant behavior at dynamic interfaces is crucial for various applications.
- Previous studies often lack precise control over hydrodynamic conditions like surface expansion rates.
Purpose of the Study:
- To investigate surfactant adsorption dynamics at a rapidly expanding liquid surface.
- To correlate surface concentration with hydrodynamic parameters and Marangoni effects.
- To evaluate a novel experimental setup for studying interfacial phenomena.
Main Methods:
- Utilized a gravity-driven laminar water jet (Re 1000-2000) with high surface expansion rates (up to 300 s⁻¹).
- Employed ellipsometry for surface concentration measurements of hexadecyltrimethylammonium bromide (C16TAB).
- Used laser Doppler velocimetry for simultaneous velocity profile measurements within the jet.
Main Results:
- Observed low surfactant concentration near the nozzle due to rapid surface expansion.
- Demonstrated Marangoni stress deceleration of surface velocity at higher downstream concentrations.
- Found significantly reduced adsorption in the presence of 0.2 M salt, attributed to micelle formation.
Conclusions:
- The laminar water jet system effectively probes surfactant adsorption and Marangoni flow under controlled conditions.
- High surface expansion rates play a critical role in limiting initial surfactant adsorption.
- The presence of salt influences surfactant aggregation and transport, impacting adsorption behavior.