Oxidative degradation of aromatic N-compounds using cobalt containing montmorillonite-based catalysts

Abstract

The goal of this work was the synthesis of a montmorillonite based catalyst for advanced oxidative degradation of organic water pollutants. Montmorillonite (Mt) –rich bentonite was acid-activated (MtA), and impregnated with cobalt (II) solution using the incipient wetness impregnation method. The impregnation was followed by heat treatment. Cobalt(II) ions were added in the quantities corresponding to 0.5 and 1.0 of the cation exchange capacity value. All samples were characterized by using chemical analysis, X-ray powder diffraction (XRPD), Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) coupled with Energy-dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) and low temperature N2 physisorption. The incorporation of the cobalt in the impregnated samples and the development of porous structure in the acid-activated ones were confirmed. The montmorillonite (Mt) was used as a catalyst support, while the cobalt in its oxide form was responsible for the generation of sulfo-radicals from Oxone®. Two aromatic N-compounds were tested as model pollutants: diazo dye - Acid Orange 10 (AO10) and nicotine. It was found that the synthesized catalysts could be used for the degradation of both pollutants, although more efficiently in AO10 degradation. The acid activation, higher cobalt loading, and temperature were found to be beneficial for the degradation of AO10.