par Wylock, Christophe 
;Rednikov, Alexei ;Haut, Benoît ;Colinet, Pierre
Référence Journal of Physical Chemistry B, 118, 38, page (11323-11329)
Publication Publié, 2014-09-02
;Rednikov, Alexei ;Haut, Benoît ;Colinet, Pierre Référence Journal of Physical Chemistry B, 118, 38, page (11323-11329)
Publication Publié, 2014-09-02
Article révisé par les pairs
| Résumé : | Density variations induced by gas absorption in reactive aqueous solutions often trigger buoyancy-induced motions, generally in the form of plumes monotonically sinking into the bulk liquid and enhancing the absorption rate. Here, we contrast two types of CO2-absorbing alkaline solutions, studying their dynamics inside a vertical Hele-Shaw cell by interferometry. While the first one indeed behaves as expected, the second one leads to a quite unusual oscillatory (phase-slipping) dynamics of convective plumes, which moreover does not lead to a significant transfer enhancement. Thanks to a simplified model of momentum and species transport, we show that this particular dynamics is related to a non-monotonic density stratification, resulting in a stagnant layer close to the interface. Conditions for this to occur are highlighted in terms of the ratios of species' diffusivities and their contribution to density, a classification deemed to be useful for optimizing chemisorption (e.g. for CO2 capture or sequestration) processes. |
