Comparative removal of Magenta MB from aqueous solution by homogeneous and heterogeneous photo-Fenton processes

Wastewaters originating from dyes production and application industries pose a major threat to surrounding ecosystems because of their toxicity and potentially carcinogenic nature. In this study, the removal of a reactive azo dye called Magenta MB (MMB) was done by photo-Fenton process using heterogeneous Fe3O4 catalyst and homogeneous FeSO4 catalyst. The effect of different system variables namely catalyst concentration, H2O2 dosage, pH, and initial concentration of the dye were studied. The influence of inorganic salts and ligands in the photo-Fenton system were examined. The stability of Fe3O4 catalyst has also been determined. The homogeneous photo-Fenton system exhibited the highest removal efficiency of 96.7% under the operating conditions of catalyst concentration of 300mgL(-1), H2O2 dosage of 9gL(-1), initial pH of 2.5, and concentration of MMB of 50mgL(-1). The optimum operating condition as per the experimental results for the heterogeneous photo-Fenton system, while using Fe3O4 catalyst is 500mgL(-1) of catalyst dosage and 6gL(-1) of H2O2 dosage for 50mgL(-1) of initial dye concentration at an initial pH of 2.5 in 90min with a dye removal efficiency of 94.9%. The addition of salts and ligands were found to be having an inhibiting effect on the Fenton system. Results showed that magnetite was found to be an efficient photo-Fenton catalyst for dye removal.