Effect of pH on Fenton and Fenton-like oxidation.

The lifetime of H2O2 is an important factor in the feasibility of Fenton's reaction for soil and groundwater remediation. The lifetime of H2O2 was evaluated in Fenton's reaction and Fenton-like reactions with haematite and magnetite. H2O2 was more stable in the Fenton-like reaction than in the Fenton's reaction. The lifetime of H2O2 was also highly affected by the solution pH, and a pH buffered acidic condition was preferred. Fenton's reaction and Fenton-like reaction were tested for phenanthrene adsorbed on sand. Fenton-like reaction and acidic condition showed better degradation rates in comparing with those of Fenton's reaction and unbuffered systems. The dissolved iron species were measured in the Fenton's reaction, and Fenton-like reaction with haematite as a function of pH. In the presence of H2O2, ferric iron was the major dissolved iron species and the pH buffered to acidic condition maintained relatively high levels of dissolved iron in the aqueous solution. The higher iron concentration in the solution contributed to effective production of hydroxyl radical and degradation of organic contaminants.