Degradation of reactive dye using heterogeneous photo-Fenton catalysts: ZnFe2O4 and GO-ZnFe2O4 composite

Dyes, being potential pollutants, need alarming attention for their degradation from wastewater. Advanced oxidation processes (AOPs) are among the most effective methodology for the degradation of pollutants. In the present study, the heterogeneous photo-Fenton catalysts (ZnFe _2 O _4 and graphene oxide based ZnFe _2 O _4 composite) were prepared and used to study the degradation of synzol red reactive dye. The prepared catalysts were well characterized by using SEM, FTIR and XRD analysis. The effect of various parameters like pH, catalysts dosage, H _2 O _2 dosage, effect of dye concentration and irradiation time during heterogeneous photo-Fenton processes was studied. The results showed 57% and 94% degradation of dye under optimized conditions (e.g. pH = 3, Catalysts dose = 75 mg l ^−1 for ZnFe _2 O _4 and 50 mg l ^−1 for GO- ZnFe _2 O _4 , H _2 O _2 dose = 27 mM and irradiation time of 60 min) was observed for ZnFe _2 O _4 and GO-ZnFe _2 O _4 , respectively. A comparison of degradation potential of catalysts using various light sources like UV-254 nm, ambient solar light and white LED, was studied. The current findings support the application of solar and LED light for the degradation of organic pollutants in wastewater. The stability and reusability of these catalysts for the degradation of the dye were also studied. The GO- ZnFe _2 O _4 composite showed negligible iron leaching and no considerable reduction in degradation efficiency upto six consecutive cycles of reusability. It has been found that the composite (GO–ZnFe _2 O _4 ) showed enhanced degradation of dye as compared to ZnFe _2 O _4 .