The aim of the study was to assess and optimize the UV/S2O82− (activated persulfate ion), Fe2+/H2O2 (Fenton), UV/Fe2+/H2O2 (photo-Fenton), and their hybridized processes for discoloration, degradation and mineralization of an azo dye, Direct Red 16, as a model pollutant, in aqueous media. A special air bubbling photo-reactor, with a perfect photon utilizing of an only 6 W, UV-C light source, was employed and a promising hybridized homogeneous AOP, as: UV/S2O82−/Fe2+/H2O2, under initial natural pH of 6.0, was introduced. This process exhibits a rapid discoloration (100% in 30 min), as well as aromatic rings degradation (more than 86% in 40 min) and mineralization (more than 50% in 60 min) of DR16 with 30 mg/L initial concentration at 25 °C. The optimum parameters of initial pH, initial reagents dosage and temperature were reported for each process. The ferrous ion catalyst concentration was much less than its standard limit. Different processes kinetic relationships were introduced in a power law model and as a function of dye concentration and temperature. Moreover, synergism impact of UV light on the catalytic center of Fenton process was proved based on a kinetic analysis.
