NiFe(C₂O₄)_x as a heterogeneous Fenton catalyst for removal of methyl orange

This paper studies a heterogeneous Fenton catalyst NiFe(C₂O₄)_x, which showed better catalytic activity than Ni(C₂O₄)_x and better re-usability than Fe(C₂O₄)_x. The methyl orange removal efficiency was 98% in heterogeneous Fenton system using NiFe(C₂O₄)_x. The prepared NiFe(C₂O₄)_x had a laminated shape and the size was in the range of 2-4 μm, and Ni was doped into catalyst's structure successfully. The NiFe(C₂O₄)_x had a synergistic effect of catalyst of 24.7 for methyl orange removal, and the dope of Ni significantly reduced the leaching of Fe by 77%. The reaction factors and kinetics were investigated. Under the optimal conditions, 0.4 g/L of catalyst dose and 10 mmol/L of hydrogen peroxide concentration, 98% of methyl orange was removed within 20 min. Analysis showed that hydroxyl radicals and superoxide radicals participated in the reaction. With NiFe(C₂O₄)_x catalyst, the suitable pH range for heterogeneous Fenton system was wide from 3 to 10. The catalyst showed good efficiency after five times re-use. NiFe(C₂O₄)_x provided great potential in treatment of refractory wastewater with excellent property.