MASS TRANSFER IN FOAMS IN ONE, TWO AND THREE DIMENSIONS
| When |
Nov 07, 2023
from 11:00 to 12:00 |
|---|---|
| Where | Salle des thèses |
| Attendees |
Benjamin Dollet |
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Environmental concerns are an increasing driving force to develop new processes, for instance in carbon dioxide capture or rare metal recycling, which must be cheap, consume little energy, and produce little waste. Liquid foams are good candidates for many of these processes, because of their easy production, small weight, and high specific surface. In this talk, I will show that they are ideal candidates for operations requiring gas and liquid transfers, starting by two fundamental studies on gas transfer through foams, and showing an application for metal leaching.
To study gas transfer, I will start showing how a one-dimensional foam, constituted by a train of bubbles made of a gas insoluble in the liquid phase of the films, evolve in time when put into contact with a soluble gas. The bubbles display spontaneous swelling, which I rationalise with a model based on gas transfer across single films separating two bubbles of different gas compositions. I show that this leads to a transport in terms of an effective nonlinear diffusion, in excellent agreement with data. I then show our recent experimental studies on the evolution of a two-dimensional foam initially made of carbon dioxide, and put into contact by either a bubble, or a full front, of air.
In the final part, I will show an application of bulk three-dimensional foams used as a medium to dissolve metals. The two reactants necessary for dissolution: acid and oxygen, are transported respectively through the bubbles and through the network of liquid channels, by forced drainage. I will show the existence of an optimal liquid flow rate that maximises the dissolution rate and explain this optimum.