Effect of hydrogen peroxide on aniline oxidation by electro-Fenton and fluidized-bed Fenton processes

In this study, the electro-Fenton and fluidized-bed Fenton processes under the given conditions were used to oxidize aniline. Factors such as feeding mode and concentration of the hydrogen peroxide were explored. Results showed that the feeding mode of H(2)O(2) did not significantly affect the aniline oxidation in the electro-Fenton process. However, the aniline oxidation slightly decreased with the two-step addition of H(2)O(2) in the fluidized-bed Fenton process. Presumably the decline of remaining Fe(2+) led to destitute hydrogen radicals from the Fe(2+)-catalyzed H(2)O(2). In addition, the removal efficiency of aniline was maintained at a maximum as H(2)O(2) concentration was higher than 0.04 M in the electro-Fenton process. Meanwhile, the almost exhausted H(2)O(2) would increase the amount of Fe(2+) in the solution for the electro-Fenton process. This is because the Fe(2+) is regenerated through the reduction of Fe(3+) on the cathode. The electro-Fenton process has a stronger oxidative ability with regard to the production of the oxalic acid than fluidized-bed Fenton process which was attributed to a higher consumption of H(2)O(2). Therefore, in the aspect of H(2)O(2) depletion, the mineralization efficiency of the fluidized-bed Fenton process was higher than that of the electro-Fenton process.