The influence of Fe-N coordination structure on the formation of reactive species in carbon-based Fenton-like system

Abstract

Oxidation performance of the Fenton-like technology decreases under near-neutral and high-salt conditions, which will hinder the deep removal of emerging contaminants (ECs). In this work, the coordination environment of Fe sites in carbon-based catalysts was regulated by gradient heating, and the model contaminant bisphenol A (BPA) was effectively degraded under near-neutral (pH=5.0–9.0) and high-salt (TDS=2922–7102 mg/L) conditions. The results show that the reactive species dominated by ¹O₂ (55.84 %) and high-valent iron-oxo (44.16 %) were generated in Fe-NC-700/PMS system. According to the extended X-ray absorption fine structure and Mössbauer spectroscopy, the coordination number of Fe-N in Fe-NC-700 was 3.4. The higher isomer shift values (0.384 mm s⁻¹) and lower binding energy (712.87 eV) of Fe 2p orbitals in Fe-NC-700, compared with the catalysts obtained under other temperature, will facilitate the formation of ¹O₂ and high-valent iron-oxo through oxygen transfer process. And these non-radical species will overcome the bottleneck of ECs removal under near-neutral and high-salt conditions, and bring an enlightenment for the advanced purification of wastewater.