To understand the the mechanism of the dynamic interfacial tension (DIFT), people always consider the diffusion process. For example, The Ward and Tordai equation is a well-known model to fit the DIFT data measured by the maximum bubble pressure method. But I am curious about whether people have considered the convection process as well? I searched for a while but couldn't find any literature discussing on it. By talking about the "convection", I mean, for example, when we do the maximum bubble pressure test, the bubble will be pushed out of a capillary tube, and this process pushes the solution around the bubble as well, and thus the convective flow occurs. In this case, won't the surfactant been carried by the convective flow as well? In this case, the drifting of the surfactant in the solution should be governed by the diffusion and the convection together. Similarly, the convective flow may also occur in the pendant drop, du nouy ring or any other surface tension measurement methods.
I wonder why people don't care about the convection? Or it's indeed negligible?
Thanks a lot in advance for any discussion!
To start the discussion, I recommend reading the problem from specialists.
Surfactants: Chemistry, Interfacial Properties, Applications
D. Möbius, R. Miller, V.B. Fainerman
The WT model incorporates diffusion-like relocation of molecules from subsurface layer into surface layer, and the relocation is possible as long as molecules posses energy higher than activation energy barrier of the adsorption process. This barrier may be due to the a certain configuration molecules have to adopt at the interface, or result from the availability of ‘‘empty sites” at the interface, which may also hinder the adsorption via a back-transport into the bulk. The description provided suits classical diffusion mechanism. Eventually, it is possible to model the bulk transport process by incorporating f.e. convection (resulting from the presence of body forces and/or pressure gradients); I believe, however, the convective mechanism doesnt physically suits the interface effect you mentioned. You can find more information in my paper "A wettability-based approach for the monitoring of drug transport through biological membranes" section 2.2. Cheers!
- Badges
- Science topic
- Similar topics
- Linguistics
- Composition Studies
- Writing