Decolorization and degradation of 2,4-dinitrophenol by Fenton's reagent

The Fenton's reagent was applied to decolor and degrade 2,4-dinitrophenol ( DNP). Different concentrations of ferrous ion (Fe2+) and hydrogen peroxide (H2O2) were dosed to investigate their influences on the removal of DNP. Th e ADMI color value was adopted as an index to indicate the decoloring perfo rmance of the reaction. Low molecular weight of organic acids was monitored , and the role of dissolved oxygen during the DNP degradation was discussed . Results show that due to productions of colored intermediates and the oxali c acid, DNP was quickly removed, followed by the ADMI color value and DOC, respectively. Both initial removal rates of DNP and ADMI color value increa sed linearly at low dosages of Fe2+ and H2O2. A high dosage of Fe2+ (> 1mM) led to an insignificant response of the initial removal rate of DNP, where as the initial removal rate of ADMI color value was not affected and kept i ncreasing constantly. Because of the non-selective feature of the hydroxyl radical, leveling off in the initial removal rates of DNP and ADMI color va lue was observed when dosing with a high concentration of H2O2. The variati on in dissolved oxygen associated with a change in color led to a proposed pathway to depict the oxidation of DNP in a Fenton's reaction.