The dose and ratio effects of Fe(II) and H2O2 in Fenton's process on the removal of atrazine

The degradation of pesticide, atrazine (ATZ), 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine, by Fenton's reagent (FR) was investigated as a function of reagents' concentrations and ratios in a batch reactor. The degradation of ATZ was effectively achieved by hydroxyl radicals, which were generated in the FR process. The decay rates of ATZ and the oxidation capacities of FR were found to depend on the concentrations of hydrogen peroxide and ferrous ion. The removal kinetics of ATZ are initiated by a rapid decay and then followed by a much slower one. After an extended reaction time (5 to 10 minutes), the reactions ceased because the Fe2+ and H2O2 were consumable and would be deactivated in the process. The oxidation capacity of FR was found to have a nonlinear correlation to the doses of [Fe2+] and [H2O2] due to the involvement of some unwanted side reactions at both high and low FR ratios. In addition, it was also found that the FR ratio has little effect on the oxidation capacity at high [Fe2+] concentration, but it becomes more critical at lower [Fe2+], which is justified by the involvement of two parallel pathways for the oxidation of ATZ, i.e. the catalyzed oxidation of ATZ induced by FR and the direct oxidation of ATZ by H2O2.