Iron-Catalyzed Oxidation and Coagulation for the Removal of Humic Acids

초록

In this study, influences of addition of either iron species and/or mineral particles on the oxidation of the humic acids(HA) using hydrogen peroxide were investigated. The results from this study could provide useful basic information for the understanding of the iron-catalytic oxidation and coagulation for the HA removal. Changes in the molecular and structural characteristics of HA and degradations of halocarbon precursors during iron catalyzed Fenton oxidation and photo-Fenton processes were studied. It was observed that oxidation rate of HA was increased which induced the reduction of naturally occurring Fe(III) ions to Fe(II) producing active oxygen species like superoxides. Dissipation of H2O2 with reaction time was escalated when the M-Fe ion added, indicating that pre-hydrolyzed species (i.e. FeOH+) might significantly scavenge the amount of H2O2. At acidic pH band(< 5.0), the proportion of hydrophobic fractions of HA suspected to be DBPs precursors decreased. From the NMR spectra and Py-GC mass analyses, alkyl compounds and dietyl ether identified after Fenton and photo-Fenton reaction being completed. These products could be formed via radical coupling and/or via peroxy radical addition to the unsaturated groups (e.g. vinyl and aromatic groups). In contrast, aromatic compounds were not observed since they were considerably decomposed during Fenton and photo-Fenton oxidation.