Reactive absorption of CO2 in NaOH: Detailed study of enhancement factor models

•The modeling of mass transfer during reactive absorption is assessed.•A simplified treatment excludes possible errors from hydrodynamic modeling.•Different expressions for the enhancement factor are evaluated.•For general conditions, carbonate-bicarbonate equilibrium must be taken into account.•At lower pH, hydration of CO2 has to be considered in addition to hydroxylation.

In a pioneering study, Darmana et al. (2007), considered the reactive absorption of CO2 in aqueous NaOH in a bubble column. Although quite good agreement was obtained between an Euler-Lagrange simulation and measured pH-values at a single point, a number of aspects of the model deserve further discussion. This will be provided in the present work by using a simplified treatment that applies at the measurement location. Particularly relevant is the enhancement factor, which describes the effect of the chemical reaction on the mass transfer. An investigation of alternative expressions for this quantity is given, based on which an improved match with the data can be obtained. Furthermore, the complete network of possible reactions in this system has to be considered.