Degradation of -nitrophenol by nano-pyrite catalyzed Fenton reaction with enhanced peroxide utilization.

Pyrite (FeS) catalyzed conversion of HO into oxidants is increasingly recognized as a promising Fenton-like process for treating recalcitrant contaminants. However, the underlying mechanism remains unclear, especially for nano-pyrite. The present study explored the potential of a nano-pyrite Fenton system for -nitrophenol oxidation using high energy ball milled nano-pyrite. The enhancement in ˙OH production, with 3 times faster -nitrophenol degradation than the conventional Fenton system, is ascribed to the reduction of pyrite size to the nanoscale, which alters the Fe regeneration pathway, favoring faster and very efficient production of ˙OH during HO decomposition. The amount of HO required was reduced due to the increased conversion efficiency of HO to ˙OH from 13.90% (conventional Fenton) to 67.55%, in which surface S species served as an electron source. An interpretation of the degradation intermediates and mineralization pathway of -nitrophenol was then made using gas chromatography-mass spectrometry. This study bridges the knowledge gap between -nitrophenol removal and the nano-pyrite catalyzed oxidant generation process.