The fate of aniline after a photo-fenton reaction in an aqueous system containing iron(III), humic acid, and hydrogen peroxide

The degradation of aniline (ArNH2) was facilitated by light irradiation (lambda similar to 370 nm) of an aqueous solution, which contained Fe(III), humic acid (HA), and H2O2. The consumption of H2O2 and the reduction of Fe(III) to Fe(II) was consistent with the degradation of ArNH2 via the photo-fenton reaction, accompanied by the generation of hydroxyl radicals (HO .). HPLC analysis of the reaction mixture indicated the presence of p-aminophenol, p-hydroquinone, and maleic and fumaric acids and the simultaneous release of NH4+ ion. However, the sum of the product concentrations, as determined by HPLC after the reaction, was much smaller than the ArNH2 concentration added initially. This can be attributed to the majority of the ArNH2 being incorporated into the polymeric structure in the HA after the reaction. The N-15 NMR and pyrolysis-GC/MS studies indicated that, after the reaction, ArNH2 formed covalent bonds with quinone and the vinyl carbons in the HA, to form anilino-compounds, such as anilinoquinone and enaminone.