Photooxidation of azo dye in aqueous dispersions of H2O2/α-FeOOH

The photodegradation of an azo dye, Mordant Yellow 10 (MY 10), in aqueous dispersions of goethite (alpha-FeOOH)/H2O2 at neutral pHs under UV irradiation was studied in comparison with the dark reaction. It was found that UV irradiation could significantly accelerate the degradation of MY10. This provides an alternative approach to the treatment of non-biodegradable azo dye pollutants. The degradation process were investigated by infrared (IR), H-1 NMR, total organic carbon (TOC) and gas chromatography-mass spectroscopy (GC-MS) analysis. Evidence for enhancement of (OH)-O-. radical generation by UV irradiation was obtained using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin-trapping EPR spectroscopy. A possible degradation mechanism of MY10 by alpha-FeOOH/H2O2 under UV irradiation was proposed, which involves the photolysis of the surface complex of H2O2 with the oxide surface metal centers to produce (OH)-O-. radicals, leading to the decomposition of organic compounds. (C) 2002 Published by Elsevier Science B.V.