Low-cost synthesis of Cu/α-Fe2O3 from natural HFeO2: Application in 4-nitrophenol reduction

Abstract Nitro-aromatic compounds pollute the aquatic environment and human being may ingest them through drinking water. Among these, 4-nitrophenol is the most common. In presence of an excess of NaBH4, 4-nitrophenol catalytically reduces to 4-aminophenol, which is not toxic. In this work, the Cu/α-Fe2O3 materials were successfully prepared via a simple classical impregnation. The natural hematiteα-Fe2O3 support was obtained from natural goethite by a simple thermal treatment and supported on it a mass ratio of 5 % or20 % of Cu at room temperature. The composition and the structural-morphological properties of natural α-Fe2O3 and Cu/α-Fe2O3 were identified by several characterization methods, including thermo gravimetric analysis (TGA), X-ray fluorescence (XRF), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), particle size distribution (PSD), and nitrogen adsorption-desorption at 77 K. The Cu/α-Fe2O3 materials composite presented spherical and uniform particle, high porosity, good copper dispersion and a mixture structural phase composition, all these characteristics and the active site nature on her surface bring to approving the excellence catalytic performance of this solid compared to the α-Fe2O3.The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) is completed in 250 s over natural α-Fe2O3, and in 50 s over Cu/α-Fe2O3 (20 %Wt of Cu), the corresponding rate constant (k) for reduction reaction was 0.09 s-1 per mg of Cu/α-Fe2O3 catalyst.