F. López

Practical identifiability analysis in dynamic gas-liquid reactors Optimal experimental design for mass-transfer parameters determination

Abstract A dynamic gas–liquid transfer model without chemical reaction based on the unsteady film theory is analysed in order to confirm the possible identifiable parameters of the model from a given set of experimental data. The structural identifiability analysis of the model using the macroscopic concentrations at the gas and liquid phase shows that the identifiable parameters of the model are the gas hold-up, ɛ , the Henrys constant, H , the reciprocal of the diffusion time, D / δ 2 , and the volumetric mass-transfer coefficient, k L a . A procedure for the optimal experimental design is proposed based on the analysis of the Fisher information matrix of the model. The analysis concludes that the measure of the dynamics of the concentration just in the liquid phase leads to important systematic errors in the determination of k L a . The importance of the concentration measurement simultaneously in the gas and the liquid phase for the parameter estimation is demonstrated and discussed.

Mathematical Model for Monitoring Gas-Liquid Reactors by Means of Continuous Flow Analysis

A Global Mathematical Model, which predicts the observed signal in a detector when Continuous Flow Analysis (CFA) is used for the monitoring of ozone gas-liquid reactors, has been proposed. This model combines the description of mass transfer and kinetic processes in the reactor (based on Surface Renewal and Film Layer theories) with dispersion in the manifold of the CFA. To validate the Global Model, the reaction between ozone and a dye (blue indigo trisulfonate) in a semi-batch gas-liquid reactor monitored by CFA is investigated.

Unstationary film model for the determination of absolute gas-liquid kinetic rate constants: ozonation of Acid Red 27, Acid Orange 7, and Acid Blue 129

A method for the determination of absolute kinetic rate constants is proposed using an unstationary film model. This methodology avoids the experimental determination of parameters like the enhancement factor or the Hatta number which are usually model-dependent. The mathematical model is general for gas-liquid systems with irreversible second order reactions. An optimization procedure based on artificial neural networks is used to estimate the initial guess of the parameters and the subsequent application of Gauss-Newton algorithm for the final nonlinear parameter estimation. The model is tested with the ozonation reaction of Acid Red 27, Acid Orange 7 and Acid Blue 129. The second-order kinetic rate constants for the direct reaction with O3 are 1615 ± 93, 609 ± 83, and 49 ± 2 M−1s−1, respectively.

Abatement of industrial sulfonic pollutants by ozone and UV radiation

p-Toluenesulfonic acid has been used as a model compound for the degradative oxidation of sulfonic compounds found in industrial wastewaters. The effect of ozone and UV has been studied in both acidic and basic media. Experiments in the presence of t-butanol support the involvement of hydroxyl radicals. Two experimental setups have been employed for ozone oxidation of the pollutant; the experimental data fit theoretical expectations in both cases. Finally, the studies have been e xtended to the degradation of a commercial surfactant having a sulfonic acid structure, namely dodecylbenzenesulfonate.

Study of the Ozonation of a Dye Using Kinetic Information Reconstruction

In this study, the kinetic information reconstruction method is applied to measure the degradation of a dye in an ozonation gas-liquid reactor. The application of this method combined with the study of the ozone gas phase concentration has made possible a deeper study of the fast reaction between ozone and blue indigo trisulfonate. For this kinetic study different rigorous mathematical models based on Film Layer Theory, Surface Renewal Model and Penetration Theory have been used.