“…Considering the total mineralization of compounds, the photocatalytic ozonation has specific energy consumption much lower than conventional photocatalysis and ozonation. The Fenton's reagent and its alterations, such as the thermal Fenton process or the photo-Fenton reaction using Fe (II)/ Fe (III) oxalate ion, H 2 O 2 and UV radiation have established much consideration as a means for the whitening of synthetic dyes [69,70]. In the photo -Fenton technique, H 2 O 2 is used swiftly in three synchronized reactions and the shortest action of Fenton, photo -reduction of Fe (III) ions to Fe (II) and H 2 O 2 photolysis.…”