Decolorization of Direct Orange 26 by heterogeneous Fenton oxidation

In this work, the decolorization of Direct Orange 26 (DO26) was conducted using Fe(III)-sepiolite catalyst in the presence of hydrogen peroxide (H2O2) in a batch process. The catalyst was prepared by ion exchange. All experiments were performed on a laboratory-scale setup. The effects of different parameters such as solution pH, catalyst concentration, initial concentration of H2O2 and DO26, stirring speed on the decolorization efficiency of the process were studied. The best reaction conditions were found to be an initial pH of 2.0 when the concentration of catalyst was 1.5g/L with [H2O2](o) of 35mM, [DO26](o) of 40mg/L, and a stirring speed of 250rpm at a temperature of 25 degrees C. Under optimal conditions, a 98% decolorization efficiency of DO26 was achieved within 60min of the reaction. The kinetics of decolorization of DO26 followed second-order reaction kinetics. Stability and reuse of the catalyst were also tested. This catalyst successfully overcomes the two problems faced by the heterogeneous Fenton process. The catalyst is reusable and the high effectivity of the catalyst in a wide range of pH.