MARANGONI INSTABILITY DURING ABSORPTION ACCOMPANIED BY CHEMICAL-REACTION

In the present paper we summarize the work, both theoretical and exper imental, done in the Institute of Chemical Engineering of the Polish A cademy of Sciences in Gliwice over almost two decades and concerning s urface phenomena accompanying the process of absorption with chemical reaction. First, a model of these phenomena is derived based on the as sumption that the cellular convection is driven by surface tension gra dients, induced in turn by infinitesimally small perturbations of conc entration. Next, experiments are presented on the absorption of carbon dioxide into aqueous solutions of monoethanolamine, diethanolamine an d sodium hydroxide. The experiments were carried out in both wetted-wa ll and packed columns, and they made it possible to describe quantitat ively the effect of the Marangoni convection on the rate of mass trans fer. Finally, it is demonstrated that the theoretical model, all its l imitations notwithstanding, allows an analysis to be carried out of ce rtain characteristics of the process of chemical absorption. Thus, the probability of oscillatory modes occurring in the system is discussed , the dimensions of the convective cells are evaluated and the gas-liq uid contact time necessary for the instability to appear is determined . The quantitative conclusions are compared with the relevant experime ntal data concerning the absorption of CO2 into monoethanolamine.