Activation of peroxydisulfate via Fe@sulfur-doped carbon-supported nanocomposite for degradation of norfloxacin: Efficiency and mechanism

In this study, Fe, S co-doped carbon-based catalysts (Fe@SCNs) for activation of peroxymonosulfate (PMS) were prepared by calcination of κ-carrageenan (κ-c) hydrogel cross-linked by Fe3+. The catalysts prepared at a κ-c concentration of 3 wt%, a Fe3+ concentration of 0.3 M and a calcination temperature of 900 °C showed the best performance for activation of PMS, allowing complete degradation of norfloxacin (NOR) within 40 min at a degradation rate of 0.2878 min−1. Different active species (1O2, OH, SO4−, O2− and FeⅣ) collaborated for the degradation of NOR, in which 1O2 dominated the reaction. The doping of S elements in carbonaceous materials could enhance the activation capacity of PMS for the reason that S-doping facilitated the electron transfer capability of the catalysts and the introduction of thiophene sulfur (CSC) generated more active sites, while S22− also enhanced the conversion of Fe3+ to Fe2+, resulting in the continuous formation of more ROS. The Fe@SCN/PMS system not only had a broad range of pH (3.0–11.0) applicability, but also was little affected by inorganic ions (NO3−, Cl−, HCO3− and H2PO4−) or organic compounds (humic acid) in water. This research provides an innovative approach for the preparation of metal and heteroatom co-doped carbon-based catalysts for sulfate radical-based advanced oxidation process.