Preparation of nanostructured pyrite with N₂ glow discharge plasma and the study of its catalytic performance in the heterogeneous Fenton process

Pyrite nanostructures were prepared from pyrite ore particles using a simple and practical plasma treatment process based on the N₂ sputtering technique. The nanostructures were characterized using different techniques, such as XRD, FT-IR, SEM, EDX, XPS, and BET analysis. The performance of the plasma-treated pyrite (PTP) was investigated as a new efficient catalyst for the decolorization of reactive orange 29 (RO29) by the heterogeneous Fenton process in a batch system. 97.6% decolorization was observed in the PTP/H₂O₂ process, which was higher than the 38.4% decolorization efficiency of the untreated pyrite/H₂O₂ process. The effects of the operational parameters on the decolorization efficiency were examined, and the 97.6% decolorization efficiency was obtained with an initial RO29 concentration of 20 mg L^-1, H₂O₂ concentration of 3 mM, catalyst dosage of 2 g L^-1, pH 5, and reaction time of 90 min. The result obtained from the successive application of PTP in the heterogeneous Fenton processes improved the stability of the catalyst in long-term applications. A plausible degradation pathway of RO29 is proposed based on gas chromatography-mass spectroscopy analysis to explain the improved degradation of RO29 through the PTP/H₂O₂ process.