Modeling the mineralization and discoloration in colored systems by (US)Fe2+/H2O2/S2O82− processes: A proposed degradation pathway

The scope of this experimental research was to study the kinetics of dye mineralization and discoloration in miscellaneous dye systems by advanced Fenton degradation, Fe2+/H2O2/S2O82−, with and without ultrasound (US) employment. Reactive azo dye C.I. Reactive Violet 2 (RV2) and C.I. Reactive Yellow 3 (RY3) as well as mordant azo dye C.I. Mordant Yellow 10 (MY10) were used as model pollutants for composition of 7 different types of model dye wastewater, i.e. MY10, RV2, RY3, MY10 + RV2, MY10 + RY3, RV2 + RY3 and MY10 + RV2 + RY3 in the concentration of 50 mg L−1. The molar ratio of Fe2+, H2O2 and K2S2O8 (equimolar) of 1:5 was used, since it was shown as optimal. Mineralization of studied systems was enhanced by simultaneous application of Fenton and US. Mineralization extents obtained after 60 min of treatment varied from minimal 49% for RV2 + RY3 system up to maximal 73% for MY10 + RV2 + RY3 system. Almost 100% of discoloration was achieved in all studied systems within few minutes of applied process. A degradation pathway of studied azo dyes was proposed and 14 variations of mathematical model describing each system and particular process have been developed.