Oxidation of azo dye carmoisine (E122) in aqueous solution by heterogeneous catalyst CuO/Al 2 O 3 system

Abstract

Heterogeneous oxidation system for the removal of azo-food dye from aqueous solution was studied in the presence of CuO/Al2O3 catalyst. This catalyst was prepared by impregnation method using a cupric salt solution at pH=5, followed by calcination at 450 °C. The result catalyst was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy- Energy Dispersive XRay Spectroscopy (SEM-EDX), where the results confirmed a high crystallinity, good chemical stability of the catalyst used in four consecutive cycles and the presence of the elements (Cu, O, Al) composing the catalyst. Several parameters affecting dye degradation such as: solution pH, H2O2 concentration, catalyst dose, and reaction temperature were investigated. CuO/Al2O3 catalyst offers higher activation efficiencies than the homogeneous Cu2+ ions, as well as good operational stability and efficiently generate HO● in neutral aqueous solutions. Complete decolorization (100 %) of Carmoisine (500 mg/L) was achieved in 240 min at neutral pH