Removal of O-toluidine by fluidized-bed fenton process

Abstract

This research investigated the removal of o-toluidine by the fluidized-bed Fenton process using the two-level-factorial and Box-Behnken designs to find the key factors and optimum conditions. Results indicate that Fe²⁺ and H₂O₂ had positive effects on o-toluidine degradation whereas the amount of carriers was not the key factor. The optimal pH, initial Fe²⁺ and H₂O₂ concentrations for the maximum o-toluidine removal (90.2% from prediction) and COD removal (41.4% from prediction) were 3, 1 mM and 17 mM, respectively. In addition, The oxidation of o-toluidine was found to be a two-stage reaction. The first stage was under the influence of Fe²⁺/H₂O₂ reaction whereas the second stage was controlled by Fe³⁺/H₂O₂ reaction. Within the studied ranges of 0.1 to 2 mM Fe²⁺, 1 to 34 mM H₂O₂, 1 mM o-toluidine, 100 g SiO₂ and pH 3, the rate law for the second stage reaction can be expressed by the following reaction: d[o-toluidine]/dt = -2.14×10⁵[Fe²⁺]¹.⁷⁷[H₂O₂]⁰.⁷⁹[OT]