Heterogeneous Fenton process by natural pyrite for removal of a textile dye from water: Effect of parameters and intermediate identification

The ability of natural pyrite particles in the degradation of C.I. Reactive Orange 29 (RO29) solution by heterogeneous Fenton (pyrite/H2O2) process was studied. X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy analysis were performed to characterize the pyrite particles. The decolorization efficiency of the RO29 by pyrite/H2O2 process was obviously influenced by pyrite particle size, suspension pH, initial concentrations of H2O2 and RO29, and pyrite dosage. Decolorization efficiency of 94.4% was resulted at the initial RO29 concentration of 10 mg/L, H2O2 concentration of 3 mM, catalyst dosage of 3 g/L, pH of 2 and reaction time of 120 min. Decolorization efficiency through pyrite/H2O2 process was not decreased significantly even after five successive cycles because of the low release (0.6 mg/L) of pyrite iron in each decolorization cycle. Plausible degradation pathway of RO29 was proposed by using gas chromatography mass spectroscopy analysis. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.