High efficiency decolorization of wastewater by Fenton catalyst: Magnetic iron-copper hybrid oxides

Abstract Fenton catalysts composed of Fe3O4/CuO nanoparticles were synthesized using co-precipitation method for the purpose of decolorization of wastewater. A high dye removal efficiency of 94 % was achieved with 20 wt% Fe3O4/CuO composition at ambient conditions and a reaction time of 90 min. Catalytic activity analysis reveal that nanoparticles with 20 wt% Fe3O4/CuO composition outperform those with 10 wt% and 30 wt% nanoparticles toward removal of methylene blue (MB) dye due to their higher surface area and smaller nano-structural size. The synthesized catalysts were characterized using XRD, EDS, FE-SEM and BET techniques. The results confirm the formation of nano-sized particles with distinct pore size and surface area. The sample with 20 wt% Fe3O4/CuO showed higher surface area in comparison with other synthesized catalysts (e.g. hybrid 10 and 30 wt% Fe3O4/CuO, single Fe3O4 and CuO oxides). Additionally, the effects of the catalyst amount, solution pH, dosage of hydrogen peroxide (H2O2), and reaction time on the catalytic performance of 20 wt% Fe3O4/CuO were evaluated. The optimum conditions to achieve the highest color removal efficiency (i.e. 94 %) were obtained at pH = 7, 50 mL reaction solution containing 10 mg/L methylene blue, 16 mmol/L of hydrogen peroxide, 0.08 g of catalyst and the reaction time of 90 min. The synthesized catalyst shows great structural stability and reusability with a dye removal efficiency higher than 90 % after five successive reaction runs. The experimental results further highlight the efficient use of hybrid metal oxides as catalysts for the removal of organic compounds from industrial wastewaters.