On bubble column reactor design for the determination of kinetic rate constants in gas–liquid systems

Abstract

AbstractThe design of a semibatch bubble column reactor with its mathematical description is proposed for the study of ozonation reactions. The mathematical model used to describe the gas–liquid mass transfer rate in the reactor is based on the unstationary film theory and the resulting model is theoretically analysed to identify its relevant parameters. After its structural identifiability analysis, the parameters are reduced to five, that is, the gas hold‐up, the ratio of diffusivities of the reacting species, the volumetric mass transfer coefficient and two time constants related with the kinetic rate constant. From the sensitivity analysis of this reduced model, we conclude that it is not sensible to the gas hold‐up and the diffusivity ratio of the reacting species for optimization purposes in moderate and slow kinetic regimes. The model is tested with the reaction between the ozone and the azo‐compound Acid Red 27. The experimental data match quite well the model allowing the estimation of the volumetric mass transfer coefficient together with the kinetic constant. The kinetic rate constant for the direct reaction between the ozone and the Acid Red 27 is estimated in k2 = 3723 ± 127 M−1 s−1 at 21.2 ± 0.5°C. The self‐coherence of the model, the absence of hypothesis about the state of the film together with the proposed optimization procedure, allows to consider the proposed methodology as a viable alternative for the study of gas–liquid systems in semi‐batch bubble columns reactors in comparison with classical approaches.