Effect of Fe²⁺ on catalytic oxidation in a fluidized bed reactor

The aim of this study was to investigate the effect of Fe²⁺ on the catalytic oxidation in the fluidized-bed reactor (FBR) applying supported γ-FeOOH as the carrier. Processes without Fe²⁺ addition and with Fe²⁺ addition (FBR-Fenton method) were performed on the oxidation of benzoic acid (BA) by H₂O₂. When Fe²⁺ was not added in the FBR, the high COD removal at low pH was caused by homogeneous catalysis of Fe²⁺ formed via reductive dissolution of γ-FeOOH. In the FBR-Fenton process, both mineralization of organics and crystallization of Fe(III) were simultaneously well performed under adequate condition. The reaction mechanism, including the reductive dissolution and crystallization of γ-FeOOH as well as the oxidation of BA, was proposed based on the experimental results.