Stéphane Mathé

Maleic Acid Ozonation: Reactor Modeling and Rate Constants Determination

This work is related to ozone treatment of organic wastes, a gas-liquid reaction. A model has been developed that accounts for mass transfer from the gas to the liquid and for the kinetics of chemical reactions. The theoretical approach of the model firstly refers to the film theory enhanced by a new parameter, the depletion factor. This method allows the part of the reaction occurring within the film and that occurring within the bulk to be distinguished. In relation with the first part of the model, the second part allows the overall behavior of a gas-liquid reactor with time to be described. The model is validated by a set of experiments on maleic acid ozonation in a semi-batch reactor.

Ozonation of Crotonic Acid Solutions: Comparison of Two Methods for the Determination of the Rate Constant

ABSTRACT This work is related to the determination of the rate constant during direct ozonation of crotonic acid which is limited by the transfer rate of ozone from the gas to the liquid. According to the literature, this constant would be 150 103 L/mol/s at pH 7, but this estimation is supported only by experimental results which are characteristic of the “instantaneous reaction regime.” It is demonstrated in this article that such a regime does not allow the correct determination of this rate constant. On the basis of the film model and by writing the mass balances for the reactor, a computer method was developed that enables the model results to be fitted with the experimental results and the rate constant to be determined. This method is used to analyze a series of results obtained in a bubble column batch reactor which are characteristic of the “intermediate reaction regime,” where the determination of the rate constant is possible. The value of 500 103 L/mol/s gives an excellent fitting.