Chemical degradation of chlorophenols with Fenton's reagent (Fe2+ + H2O2)

Aqueous solutions of Fenton's reagent (Fe2+ = H2O2) have been used to effect the total decomposition of the chlorophenols: 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, 3,4-dichlorophenol and 2,4,5-trichlorophenol. The mineralization of these chlorinated aromatic substrates to CO2 and free Cl- has been studied as a function of [Fe2+] and [HClO4]. Increasing the concentration of Fe2+ enhances the decomposition process, while an increase in the concentration of HClO4, inhibits the reaction. The presence of Fe3+ alone (without any Fe2+) with H2O2 has no effect on the degradation of the chlorophenols. In all cases, the stoichiometric quantity of free Cl- was obtained at the completion of the decomposition reaction; but the rates of disappearance of the chlorophenol and of the formation of the Cl- are not similar. This suggests that some chlorinated aliphatic species may be formed as possible intermediates.