Laboratoire Matière et Systèmes Complexes

Anne De Wit

Director of the Nonlinear Physical Chemistry Unit Service de Chimie Physique et Biologie Théorique

Université libre de Bruxelles, Belgique

Enhanced convective dissolution of CO2 in reactive systems

Abstract :

To decrease the atmospheric concentration of CO2, sequestration techniques whereby this greenhouse gas is injected in saline aquifers present in soils are considered. Upon contact with the aquifer, the CO2 can dissolve in it and subsequently be mineralized via reactions with minerals like carbonates for instance. We investigate both experimentally and theoretically the influence of such reactions on the convective dissolution of CO2. Experiments analyze convective patterns developing when gaseous CO2 is put in contact with aqueous solutions of reactants in a confined vertical Hele-Shaw geometry. We show that the reactions can enhance convection and modify the nonlinear dynamics of density fingering [1,2]. Numerical simulations further show that reactions can increase the flux of dissolving CO2, inducing a more efficient sequestration [3]. Emphasis will be put on the possibility to control the convective pattern properties by varying the very nature of the chemicals. Implications on the choice of optimal sequestration sites will be discussed.

[1] V. Loodts, C. Thomas, L. Rongy, and A. De Wit, Control of convective dissolution by chemical reactions : general classification and application to CO2 dissolution in reactive aqueous solutions, Phys. Rev. Letters, 113, 114501 (2014).

[2] C. Thomas, V. Loodts, L. Rongy, A. De Wit
, Convective dissolution of CO2 in reactive alkaline solutions : Active role of spectator ions, Int. J. Greenhouse Gas Control, 53, 230 (2016).

[3] V. Loodts, B. Knaepen, L. Rongy and A. De Wit, Enhanced steady-state dissolution flux in reactive convective dissolution, Phys. Chem. Chem. Phys., 19, 18565 (2017).

Fig : Convective dissolution of gaseous CO2 in an aqueous solution