Effect of the iron oxide catalyst on o-toluidine oxidation by the fluidized-bed fenton process.

This study investigates the effects of the Fe2+ concentration and synthetic iron oxide catalysts on o-toluidine degradation using a fluidized-bed Fenton process. The mineralization ofo-toluidine in the synthetic catalyst system is also examined. The H3.5 and H7.3 Fe/SiO2 and A7.8 and A 12.5 Fe/SiO2 catalysts were successfully synthesized by adding H202 and injecting air process, respectively. The optimum initial ferrous ion concentration for degradation of 1 mM o-toluidine was 1 mM. Experimental results reveal that 1 mM o-toluidine can be 100% degraded at 60 and 120 min in the modified fluidized-bed Fenton process with A7.8 Fe/SiO2 and the conventional fluidized-bed Fenton process with SiO2 carrier, respectively, when the optimum conditions of 1mM Fe2+ and 17mM H202 at pH 3 were used. The A7.8 Fe/SiO2 catalyst had a stronger oxidation ability than the H3.5 Fe/SiO2, H7.3 Fe/SiO2 and A12.5 Fe/SiO2 catalysts, and was attributed to the high iron content on the surface of the SiO2 support. The Fenton and Fenton-like reactions occurred in the A7.8 Fe/SiO2 catalyst system. Degradation of o-toluidine in the Fenton-like process follows pseudo-first-order kinetics. The A7.8 Fe/SiO2 catalyst efficiently enhanced o-toluidine oxidation under the pH range of 2-4.