Characteristics of p-chlorophenol oxidation by Fentonʹs reagent

The objective of this work was to probe experimentally the characteristics of the Fenton oxidation of p-chlorophenol to develop a mechanistic model that appropriately represented the mechanism. Batch experiments were carried out to investigate the effects of pH, Fe2+ and hydrogen peroxide levels, p-chlorophenol concentration and chloride level. The decomposition proceeded rapidly only within a limited pH range of 2–4. It was typical of the decomposition that an initially fast decomposition rate was significantly reduced within a few minutes. The fast initial rate was first order with p-chlorophenol and its rate constant was proportional to the initial level of Fe2+ and hydrogen peroxide. The occurrence of the slow phase of the decomposition was primarily attributed to the Fe2+ depletion caused by Fe-organic complex formation. The final extent of oxidation was limited by hydrogen peroxide. The effect of chloride was pH dependent and could be significant as its concentration increased. These experimental observations strongly suggest that the reactions accounting for the conflicting effects of organic intermediates and products and heteroatoms should properly be included in the future models.