Efficient Decomposition of Organic Pollutants over nZVI/FeOx/FeNy-Anchored NC Layers via a Novel Dual-Reaction-Centers-Based Wet Air Oxidation Process under Natural Conditions

The wet air oxidation (WAO) process is a promising advanced oxidation process used for the degradation of organic pollutants; however, severe reaction conditions, including high temperature and high pressure, have significantly limited its application. In this report, we describe a new discovery that nZVI/FeOx/FeNy-anchored NC composites (nZVI/FeN5.5O7.2/C) exhibit an excellent catalytic performance for organic pollutant removal through natural dissolved oxygen (DO) microactivation at room temperature and atmospheric pressure. Characterization techniques reveal the key structural information: a special kind of construction of dual-reaction-centers (DRCs) with electron-rich Fe microcenters (ERCs) and electron-poor C(π)/N microcenters (EPCs) is successfully constructed on the surface of the catalyst through bonding of nZVI, FeOx, and FeNy, which is responsible for the novel DRCs-WAO process. During the reaction, DO obtains electrons and is rapidly activated into active oxygen species at the ERCs. Pollutants, as electron donors, lose electrons at EPCs and are oxidized. Electron transfer between EPCs and ERCs is achieved through the constructed Fe–O–C and Fe–N bonding bridges. This process is even free from the interference of inorganic ions, pH, or natural organic matter in the water environment. Our findings address the key limitation of the classical WAO process and are of positive significance for developing new wastewater treatment technologies with low energy consumption and high efficiency.