Water Remediation from Recalcitrant Pollution Using the Galvano-Fenton Process: A Modeling Approach of the Hydroxyl Radical Generation and the Energy Efficiency

Abstract

The hydroxyl radical is the most powerful oxidant after fluorine, and is the key reactant of theadvanced oxidation processes AOP. Monitoring the kinetics of formation and reaction of this short life speciesis one of the challenging tasks from an experimental point of view. Thus, modelling is suggested to be oneefficient tool for a comprehensive and predictive study of AOPs, particularly the Galvano-Fenton process. In thepresent study, mathematical modelling is used to describe the kinetics of hydroxyl radical ????????• generation andorganic substrate ???????? degradation within the Galvano-Fenton process, based on the spontaneous galvaniccorrosion of iron waste and in situ ferrous ion catalyst generation. A range of typical absolute kinetic constantsof 106 à 1010 M-1.s-1 is considered to characterize the attack of ???????? species by ????????•. Phenol is presented as amodel pollutant for a total mineralization model. The numerical simulations demonstration a quasi-linearevolution of hydroxyl radical production during the first stage of the Galvano-Fenton process. A comparison ofthe Galvano-Fenton process with the classic Fenton in terms of kinetics, and electro-Fenton in terms ofenergetic performance, revealed that the spontaneous galvanic generation of ferrous ions in the Galvano-Fentonprocess leads to a higher rate of the reaction a higher instantaneous concentration of ferric ions accompanyingthe release of hydroxyl radicals and hence a better oxidation efficiency, as well as a positive energy balance. Aparticular attention was given to the ratio of the degradation efficiency to the released energy.