Tartrazine azo-dye degradation using Co-impregnated Al-pillared clay and Oxone: influence of temperature

Heterogneous Fenton-like reaction is one of the most efficient solutions for the degradation of organic pollutants in water. A variant of this reaction involves the application of Oxone reagent, based on potassium peroxymonosulfate. Oxone, in conjunction with cobalt, is the source of sulfate radicals. These radicals are very efficient oxidants because of their high standard reduction potential at neutral pH. In this work Co-impregnated Al-pillared clay (CoAP2) was used as heterogeneous catalyst in the degradation of Tartrazine azo-dye in aqueous solutions. For this purpose, Namontmorillonite source clay from Wyoming, USA, with particle diameters of up to 2×10-6 m was submitted to pillaring with aluminium (Keggin ions) and subsequent impregnation with Co(NO3)2 followed by calcination. Morphological and textural characterization as well as phase and chemical characterization were performed on the obtained material. Catalytic degadation of Tartrazine using CoAP2 and Oxone was investigated with respect to reaction temperature in the range from 30–70 °C and monitored using UV-Vis spectroscopy. The obtained spectra indicated that solution decolorization was efficient. Increasing temperature increased decolorization efficiency, and led to the degradation of the dye, the formation and subsequent disappearance of different reaction products. The catalyst showed to be stable under investigated conditions.