Dynamic simulation of degradation of toluene in waste gas by the photo-Fenton reaction in a bubble column

A dynamic simulation model for the novel toluene gas removal chemical-absorption process based on the photo-Fenton reaction has been developed. It can predict the unsteady- and steady-state performance of a bubble column reactor for photo-Fenton degradation of toluene in a waste gas. In modeling, reaction kinetics in the liquid phase and gas–liquid mass transfer were combined with the tanks-in-series model for nonideal mixing in the gas and liquid phases. The rate equations for Fenton reagents (Fe ions and H2O2), OH radical and the intermediates were included besides those for toluene in the gas and liquid phases. The iron redox cycle generating hydroxyl radical is a key process in the photo-Fenton process. In the simulation model, therefore, the iron redox cycling was taken into account. Experiments for toluene gas photo-Fenton degradation in a semi-batch bubble column were conducted to elucidate the reaction kinetics and to verify the capability of the proposed dynamic simulation model. The proposed simulation model could satisfactorily represent the rather complicated dynamic changes of toluene concentrations in the gas and liquid phases, hydrogen peroxide, iron ions and intermediates during the course of the photo-Fenton process controlled by the iron redox cycle, which was established firstly by the Fenton reaction with the presence of H2O2 and subsequently by the UV light and dissolved oxygen after the complete consumption of H2O2.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (177 K)Download as PowerPoint slideHighlights► A dynamic simulation model for toluene gas photo-Fenton degradation was developed. ► Reaction kinetics and mass transfer were combined with the nonideal mixing model. ► Experiments were conducted to elucidate the reaction kinetics. ► The model could satisfactorily represent the rather complicated dynamic behaviors.