Enhancing Catalytic Degradation of Methylene Blue Through GO-CoFe2O4: Synthesis, Effect of Parameters, and Toxicity Evaluation

Catalytic decomposition based on sulfate radical (SO4•-) production is one of the important techniques in the decomposition of resistant pollutants. Ferrite (MFe2O4) nanoparticles have recently been used in polluted water treatment due to their unique features such as easy synthesis, pollutant decomposition in a short time, and application in a wide pH range. In the present study, cobalt ferrite on graphene oxide (GO-CoFe2O4) was synthesized as a persulfate (PS) activator through the sol-gel method and its characteristics were identified through XRD, SEM, TEM, BET, and VSM. Diagnostic analyses showed the magnetic properties of the catalyst with a pore size of 2 nm and  a surface area of 52 m2/g. Complete degradation of 15 mg/L MB dye was obtained at alkaline pH and dosage of 100 mg/L PS. Nitrate, sulfate, phosphate, and bicarbonate led to a decrease of more than 20% in MB removal efficiency through the formation of reactive species characterized by low oxidation potential. GO-CoFe2O4 displayed high efficiency in the activation of different oxidants (such as H2O2, PS, and PMS) in the proper degradation of MB. In the trapping experiment, hydroxyl (•OH), sulfate (SO4•-), and superoxide (O2•-) radicals were identified as active species, respectively. The synthesized catalyst showed stability of more than 4 runs for degradation of MB from aqueous medium. The toxicity of the solution was evaluated through the growth inhibition rate of pea and lentil roots, and the findings showed a 30-50% diminution in the growth inhibition rate in water treated with GO-CoFe2O4/PS. Finally, GO-CoFe2O4 composite can be suggested as a PS activator in the catalytic degradation of MB based on easy separation, excellent specific surface area, high efficiency, and acceptable recyclability.