[Kinetics of humic substances oxidation degradation by Fenton's reagent]

Humic substances (HS) oxidation degradation by Fenton's reagent was kinetically investigated in this study. HS was removed by both oxidation and coagulation during Fenton treatment. Moreover, initial pH, the dosage of Fenton's reagent and initial concentration of HS had a significant impact on HS oxidation rate and the oxidation mainly occurred at the first 60 min of reaction time. The empirical kinetic equation for HS oxidation by Fenton's reagent under the conditions of 308 K of temperature, 4.0 of pH, 5-40 mmol x L(-1) of Fe2+, 40-120 mmol x L(-1) of H2O2, 250-1 000 mg x L(-1) of HS, could be described using a kinetic model, which was fitted very well with the experimental data. The overall reaction order is 2.34. The lower activation energy of 14.9 kJ x mol(-1) shows that Fenton reaction can be initiated easily. The reaction order of H2O2 (0.86) is higher than that of Fe2+ (0.47), which indicates that the effect of initial H2O2 concentration is greater than that of Fe2+ on the oxidation degradation of HS by Fenton process.