Mass transfer with instantaneous chemical reaction in finite gas-liquid systems

The moving-boundary problem of gas absorption accompanied by an instantaneo us irreversible chemical reaction in a limited gas-liquid system has been a nalyzed. Analytical solutions have been derived, under the restrictions of equal diffusivities of the two reacting species and stoichiometric factor o f unity, for the cases of significant or negligible gas-film and surfactant -film resistances. A numerical scheme has been developed for the general ca se of unequal diffusivities and/or stoichiometric factor differing from uni ty. The effects of various parameters like film thickness, gas-bubble volum e, stoichiometric factor, initial concentration in the liquid phase, etc., have been illustrated. Furthermore, the importance of the surfactant-film a nd gas-film resistances has also been demonstrated. The analytical solution has been found to be in agreement with the numerical solution, thus demons trating the efficacy of the concept of negative concentration in solving su ch problems. (C) 2000 Elsevier Science S.A. All rights reserved.