Influence of the Active Phase (Fe, Ni, and Ni–Fe) of Mixed Oxides in CWAO of Crystal Violet

The catalytic oxidation of aqueous Crystal Violet (CV) solutions has been investigated using Ni and Fe catalysts supported over Mg-Al oxides synthetized by the auto-combustion method. The influence of temperature, loading and selectivity were studied in the catalytic wet air oxidation (CWAO) of CV. The kind of metal had an important contribution in the redox process, since significant differences between Fe, Ni and their mixtures were observed. The catalysts with only Fe as active phase were more efficient for the oxidation of CV under normal conditions (T = 25 °C and atmospheric pressure) compared to those containing Ni, revealing the influence of the transition metal on catalytic properties. It was found that iron containing materials displayed enhanced textural properties. The synthesis of Fe/MgAl catalysts by the auto-combustion method, leads to solids with excellent catalytic behavior, CV degradation of 100% in eight hours of reaction, 68% of selectivity to CO2 and significant reduction of COD (Chemical oxygen demand)